Adaptability of the Saccharomyces cerevisiae yeasts to wine fermentation conditions relies on their strong ability to consume nitrogen.

PubMed

Brice, Claire; Cubillos, Francisco A; Dequin, Sylvie; Camarasa, Carole; Martínez, Claudio

2018-01-01

Saccharomyces cerevisiae strains are genetically diverse, largely as a result of human efforts to develop strains specifically adapted to various fermentation processes. These adaptive pressures from various ecological niches have generated behavioral differences among these strains, particularly in terms of their nitrogen consumption capacities. In this work, we characterize this phenotype by the specific quantity of nitrogen consumed under oenological fermentation conditions using a new approach. Indeed, unlike previous studies, our experiments were conducted in an environment containing excess nitrogen, eliminating the nitrogen limitation/starvation factor that is generally observed in fermentation processes. Using these conditions, we evaluated differences in the nitrogen consumption capacities for a set of five strains from diverse origins. The strains presented extremely different phenotypes and variations in their capacities to take up nitrogen from a wine fermentation environment. These variations reflect the differences in the nitrogen uptake capacities between wine and non-wine strains. Finally, the strains differed in their ability to adapt to the nitrogen composition of the environment, leading to variations in the cellular stress states, fermentation performances and the activity of the nitrogen sensing signaling pathway.

Adaptability of the Saccharomyces cerevisiae yeasts to wine fermentation conditions relies on their strong ability to consume nitrogen

PubMed Central

2018-01-01

Saccharomyces cerevisiae strains are genetically diverse, largely as a result of human efforts to develop strains specifically adapted to various fermentation processes. These adaptive pressures from various ecological niches have generated behavioral differences among these strains, particularly in terms of their nitrogen consumption capacities. In this work, we characterize this phenotype by the specific quantity of nitrogen consumed under oenological fermentation conditions using a new approach. Indeed, unlike previous studies, our experiments were conducted in an environment containing excess nitrogen, eliminating the nitrogen limitation/starvation factor that is generally observed in fermentation processes. Using these conditions, we evaluated differences in the nitrogen consumption capacities for a set of five strains from diverse origins. The strains presented extremely different phenotypes and variations in their capacities to take up nitrogen from a wine fermentation environment. These variations reflect the differences in the nitrogen uptake capacities between wine and non-wine strains. Finally, the strains differed in their ability to adapt to the nitrogen composition of the environment, leading to variations in the cellular stress states, fermentation performances and the activity of the nitrogen sensing signaling pathway. PMID:29432462

BIO-PRECIPITATES PRODUCED BY TWO AUTOCHTHONOUS BORON TOLERANT STREPTOMYCES STRAINS.

PubMed

Moraga, Norma Beatriz; Irazusta, Verónica; Amoroso, María Julia; Rajal, Verónica Beatriz

2017-08-01

Boron is widespread in the environment. Although contaminated soils are hard to recover different strategies have been investigated in the recent years. Bioremediation is one of the most studied because it is eco-friendly and less costly than other techniques. The aim of this research was to evaluate whether two Streptomyces strains isolated from boron contaminated soils in Salta, Argentina, may help remove boron from such soils. For this, they were grown in different liquid media with two boric acid concentrations and their specific growth rate and specific boric acid consumption rate were determined. Both strains showed great capacity to remove boron from the media. Increasing boric acid concentrations affected negatively the specific growth rate, however the specific boric acid consumption rate was superior. Boron bio-precipitates were observed when the strains grew in the presence of boric acid, probably due to an adaptive response developed by the cells to the exposure, for which many proteins were differentially synthetized. This strategy to tolerate high concentrations of boron by immobilizing it in bio-precipitates has not been previously described, to the best of our knowledge, and may have a great potential application in remediating soils contaminated with boron compounds.

Non-Saccharomyces Yeasts Nitrogen Source Preferences: Impact on Sequential Fermentation and Wine Volatile Compounds Profile

PubMed Central

Gobert, Antoine; Tourdot-Maréchal, Raphaëlle; Morge, Christophe; Sparrow, Céline; Liu, Youzhong; Quintanilla-Casas, Beatriz; Vichi, Stefania; Alexandre, Hervé

2017-01-01

Nitrogen sources in the must are important for yeast metabolism, growth, and performance, and wine volatile compounds profile. Yeast assimilable nitrogen (YAN) deficiencies in grape must are one of the main causes of stuck and sluggish fermentation. The nitrogen requirement of Saccharomyces cerevisiae metabolism has been described in detail. However, the YAN preferences of non-Saccharomyces yeasts remain unknown despite their increasingly widespread use in winemaking. Furthermore, the impact of nitrogen consumption by non-Saccharomyces yeasts on YAN availability, alcoholic performance and volatile compounds production by S. cerevisiae in sequential fermentation has been little studied. With a view to improving the use of non-Saccharomyces yeasts in winemaking, we studied the use of amino acids and ammonium by three strains of non-Saccharomyces yeasts (Starmerella bacillaris, Metschnikowia pulcherrima, and Pichia membranifaciens) in grape juice. We first determined which nitrogen sources were preferentially used by these yeasts in pure cultures at 28 and 20°C (because few data are available). We then carried out sequential fermentations at 20°C with S. cerevisiae, to assess the impact of the non-Saccharomyces yeasts on the availability of assimilable nitrogen for S. cerevisiae. Finally, 22 volatile compounds were quantified in sequential fermentation and their levels compared with those in pure cultures of S. cerevisiae. We report here, for the first time, that non-Saccharomyces yeasts have specific amino-acid consumption profiles. Histidine, methionine, threonine, and tyrosine were not consumed by S. bacillaris, aspartic acid was assimilated very slowly by M. pulcherrima, and glutamine was not assimilated by P. membranifaciens. By contrast, cysteine appeared to be a preferred nitrogen source for all non-Saccharomyces yeasts. In sequential fermentation, these specific profiles of amino-acid consumption by non-Saccharomyces yeasts may account for some of the interactions observed here, such as poorer performances of S. cerevisiae and volatile profile changes. PMID:29163451

Non-Saccharomyces Yeasts Nitrogen Source Preferences: Impact on Sequential Fermentation and Wine Volatile Compounds Profile.

PubMed

Gobert, Antoine; Tourdot-Maréchal, Raphaëlle; Morge, Christophe; Sparrow, Céline; Liu, Youzhong; Quintanilla-Casas, Beatriz; Vichi, Stefania; Alexandre, Hervé

2017-01-01

Nitrogen sources in the must are important for yeast metabolism, growth, and performance, and wine volatile compounds profile. Yeast assimilable nitrogen (YAN) deficiencies in grape must are one of the main causes of stuck and sluggish fermentation. The nitrogen requirement of Saccharomyces cerevisiae metabolism has been described in detail. However, the YAN preferences of non- Saccharomyces yeasts remain unknown despite their increasingly widespread use in winemaking. Furthermore, the impact of nitrogen consumption by non- Saccharomyces yeasts on YAN availability, alcoholic performance and volatile compounds production by S. cerevisiae in sequential fermentation has been little studied. With a view to improving the use of non- Saccharomyces yeasts in winemaking, we studied the use of amino acids and ammonium by three strains of non- Saccharomyces yeasts ( Starmerella bacillaris, Metschnikowia pulcherrima , and Pichia membranifaciens ) in grape juice. We first determined which nitrogen sources were preferentially used by these yeasts in pure cultures at 28 and 20°C (because few data are available). We then carried out sequential fermentations at 20°C with S. cerevisiae , to assess the impact of the non- Saccharomyces yeasts on the availability of assimilable nitrogen for S. cerevisiae . Finally, 22 volatile compounds were quantified in sequential fermentation and their levels compared with those in pure cultures of S. cerevisiae . We report here, for the first time, that non- Saccharomyces yeasts have specific amino-acid consumption profiles. Histidine, methionine, threonine, and tyrosine were not consumed by S. bacillaris , aspartic acid was assimilated very slowly by M. pulcherrima , and glutamine was not assimilated by P. membranifaciens . By contrast, cysteine appeared to be a preferred nitrogen source for all non- Saccharomyces yeasts. In sequential fermentation, these specific profiles of amino-acid consumption by non- Saccharomyces yeasts may account for some of the interactions observed here, such as poorer performances of S. cerevisiae and volatile profile changes.

Food choice effects on herbivory: Intra-specific seagrass palatability and inter-specific macrophyte palatability in seagrass communities

NASA Astrophysics Data System (ADS)

Jiménez-Ramos, Rocío; Brun, Fernando G.; Egea, Luis G.; Vergara, Juan J.

2018-05-01

Interactions between the palatability and abundance of different food sources may influence herbivory patterns in seagrass-dominated communities. In addition, intra-specific differences in nutrient and structural quality of leaves may also alter seagrass palatability and generate different rates of consumption within these communities. We offered two temperate seagrasses species, (Cymodocea nodosa and Zostera noltei) from two different locations to look at intraspecific differences, and two other macrophytes, both of which occur at the same location as seagrasses but represent the extremes of palatability, to a generalist herbivore Paracentrotus lividus (purple sea urchin). Using feeding assays, we compared the consumption rates in individual (single plant species) and combined diets at different food availabilities. Intra-specific differences between seagrass species growing at different locations (inner and outer bay) were indeed found to significantly modify the consumption rate for one species. Structural traits such as carbon content were linked to the low consumption found in Cymodocea nodosa from the inner bay location. In addition, we found that the co-occurrence of different macrophyte species can result in preferential consumption of the more palatable macrophyte with high nutritional content and low structural defence over seagrasses, especially when P. lividus has an abundant food supply. Overall, our findings suggest that intra- and inter-specific differences in seagrass traits and the relative abundance of other macrophytes may explain the variability in patterns of herbivory found within seagrass communities.

Allelotype analysis of chemically induced squamous cell carcinomas in F(1) hybrids of two inbred mouse strains with different susceptibility to tumor progression.

PubMed

Stern, M C; Benavides, F; Klingelberger, E A; Conti, C J

2000-07-01

Loss of heterozygosity (LOH) at specific chromosomal loci is generally considered indirect evidence for the presence of putative suppressor genes. Allelotyping of tumors using polymorphic markers distributed throughout the entire genome allows the analysis of specific allelic losses. In the field of chemical carcinogenesis, the outbred SENCAR mouse has been commonly used to analyze the multistage nature of skin tumor development. In the study reported here we generated F(1) hybrids between two inbred strains (SENCARB/Pt and SSIN/Sprd) derived from the SENCAR stock that differ in their susceptibility to tumor progression. We typed 24 7, 12-dimethylbenz[a]anthracene and 12-O-tetradecanoylphorbol-13-acetate-induced squamous cell carcinomas for LOH using 56 microsatellite markers distributed among all autosomal chromosomes. The highest percentage of LOH, 78%, was found on chromosome 7, but there was no preferential loss of one particular allele, indicating that the putative suppressor genes found in this area are not involved in genetic susceptibility. High levels of LOH were also found on chromosomes 16 (39%), 6 (29%), 4 (25%), 9 (25%), 14 (22%), 10 (20%) and 19 (20%), but with no preferential loss of the alleles of one strain. The chromosomal regions with LOH on mouse chromosomes 4, 6, 7, 9, 10, 14, 16 and 19 correspond to regions in the human genome where LOH has been reported and have been suggested to harbor tumor suppressor genes.

The impact of caffeine use across the lifespan on cognitive performance in elderly women

USDA-ARS?s Scientific Manuscript database

Habitual caffeine consumption has often been associated with decreasing age-related cognitive decline. However, whether habitual caffeine use preferentially spares different cognitive processes is unclear. Furthermore, whether basing habitual caffeine consumption patterns on current consumption or o...

A probiotic fermented dairy drink improves antibody response to influenza vaccination in the elderly in two randomised controlled trials.

PubMed

Boge, Thierry; Rémigy, Michel; Vaudaine, Sarah; Tanguy, Jérôme; Bourdet-Sicard, Raphaëlle; van der Werf, Sylvie

2009-09-18

Influenza vaccination is recommended for the elderly in many countries, but immune responses are weaker compared to younger adults. To investigate the impact of daily consumption of a probiotic dairy drink on the immune response to influenza vaccination in an elderly population of healthy volunteers over 70 years of age. Two randomised, multicentre, double-blind, controlled studies were conducted during two vaccination seasons in 2005-2006 (pilot) and 2006-2007 (confirmatory). Eighty-six and 222 elderly volunteers consumed either a fermented dairy drink, containing the probiotic strain Lactobacillus casei DN-114 001 and yoghurt ferments (Actimel, or a non-fermented control dairy product twice daily for a period of 7 weeks (pilot) or 13 weeks (confirmatory). Vaccination occurred after 4 weeks of product consumption. Geometric mean antibody titres (GMT) against the 3 viral strains composing the vaccine (H1N1, H3N2, and B) were measured at several time intervals post-vaccination by haemagglutination inhibition test. In the pilot study, the influenza-specific antibody titres increased after vaccination, being consistently higher in the probiotic product group compared to the control group under product consumption. Similarly, in the confirmatory study, titres against the B strain increased significantly more in the probiotic group than in the control group at 3, 6 and 9 weeks post-vaccination under product consumption (p=0.020). Significant differences in seroconversion between the groups by intended to treat analysis were still found 5 months after vaccination. Similar GMT results were observed for the H3N2 strain and H1N1 strain, confirming the results of the pilot study. These studies demonstrate that daily consumption of this particular probiotic product increased relevant specific antibody responses to influenza vaccination in individuals of over 70 years of age and may therefore provide a health benefit in this population.

Construction of a Hypervirulent and Specific Mycoinsecticide for Locust Control

PubMed Central

Fang, Weiguo; Lu, Hsiao-Ling; King, Glenn F.; St. Leger, Raymond J.

2014-01-01

Locusts and grasshoppers (acridids) are among the worst pests of crops and grasslands worldwide. Metarhizium acridum, a fungal pathogen that specifically infects acridids, has been developed as a control agent but its utility is limited by slow kill time and greater expense than chemical insecticides. We found that expression of four insect specific neurotoxins improved the efficacy of M. acridum against acridids by reducing lethal dose, time to kill and food consumption. Coinoculating recombinant strains expressing AaIT1(a sodium channel blocker) and hybrid-toxin (a blocker of both potassium and calcium channels), produced synergistic effects, including an 11.5-fold reduction in LC50, 43% reduction in LT50 and a 78% reduction in food consumption. However, specificity was retained as the recombinant strains did not cause disease in non-acridids. Our results identify a repertoire of toxins with different modes of action that improve the utility of fungi as specific control agents of insects. PMID:25475694

Effects of strain variations on aging response and corrosion properties of third generation Al-Li alloys

NASA Astrophysics Data System (ADS)

Wright, Ellen E.

Due to their high specific strength (strength/density) and specific stiffness (elastic modulus/density), Al-Li alloys are attractive alloys for structural aircraft applications. To produce contoured aircraft components from Al-Li wrought products, stretch forming prior to aging is a common manufacturing technique. The effects of different amounts of tensile straining (0-9%) on the mechanical, microstructural, and corrosion properties of two third generation Al-Li alloys (2099 and 2196) were investigated. In addition to typical characterization techniques, electron backscatter diffraction (EBSD), 2D micro-digital image correlation (DIC), and scanning Kelvin probe force microscopy (SKPFM) were used to examine site-specific effects of orientation, micro-strain evolution during straining, and surface potential on corrosion, respectively. Tapping mode atomic force microscopy (AFM) was also performed to study galvanic corrosion in artificial seawater (3.5% NaCl) as it occurred in-situ. There was evidence of intergranular corrosion for 0% strain conditions, but the dominant form of corrosion was localized pitting for all specimens except Alloy 2196 strained 0%. Pitting initiated at grain boundaries and triple points. In many cases, pitting extended into particular grains and was elongated in the extrusion direction. Regions of high micro-strain preferentially corroded, and large, recrystallized grains in mostly unrecrystallized microstructures were detrimental to corrosion properties. Recommendations for improved thermomechanical processing and/or alloying to promote corrosion resistance of 2XXX series Al-Li alloys were investigated.

Development of a D-xylose fermenting and inhibitor tolerant industrial Saccharomyces cerevisiae strain with high performance in lignocellulose hydrolysates using metabolic and evolutionary engineering.

PubMed

Demeke, Mekonnen M; Dietz, Heiko; Li, Yingying; Foulquié-Moreno, María R; Mutturi, Sarma; Deprez, Sylvie; Den Abt, Tom; Bonini, Beatriz M; Liden, Gunnar; Dumortier, Françoise; Verplaetse, Alex; Boles, Eckhard; Thevelein, Johan M

2013-06-21

The production of bioethanol from lignocellulose hydrolysates requires a robust, D-xylose-fermenting and inhibitor-tolerant microorganism as catalyst. The purpose of the present work was to develop such a strain from a prime industrial yeast strain, Ethanol Red, used for bioethanol production. An expression cassette containing 13 genes including Clostridium phytofermentans XylA, encoding D-xylose isomerase (XI), and enzymes of the pentose phosphate pathway was inserted in two copies in the genome of Ethanol Red. Subsequent EMS mutagenesis, genome shuffling and selection in D-xylose-enriched lignocellulose hydrolysate, followed by multiple rounds of evolutionary engineering in complex medium with D-xylose, gradually established efficient D-xylose fermentation. The best-performing strain, GS1.11-26, showed a maximum specific D-xylose consumption rate of 1.1 g/g DW/h in synthetic medium, with complete attenuation of 35 g/L D-xylose in about 17 h. In separate hydrolysis and fermentation of lignocellulose hydrolysates of Arundo donax (giant reed), spruce and a wheat straw/hay mixture, the maximum specific D-xylose consumption rate was 0.36, 0.23 and 1.1 g/g DW inoculum/h, and the final ethanol titer was 4.2, 3.9 and 5.8% (v/v), respectively. In simultaneous saccharification and fermentation of Arundo hydrolysate, GS1.11-26 produced 32% more ethanol than the parent strain Ethanol Red, due to efficient D-xylose utilization. The high D-xylose fermentation capacity was stable after extended growth in glucose. Cell extracts of strain GS1.11-26 displayed 17-fold higher XI activity compared to the parent strain, but overexpression of XI alone was not enough to establish D-xylose fermentation. The high D-xylose consumption rate was due to synergistic interaction between the high XI activity and one or more mutations in the genome. The GS1.11-26 had a partial respiratory defect causing a reduced aerobic growth rate. An industrial yeast strain for bioethanol production with lignocellulose hydrolysates has been developed in the genetic background of a strain widely used for commercial bioethanol production. The strain uses glucose and D-xylose with high consumption rates and partial cofermentation in various lignocellulose hydrolysates with very high ethanol yield. The GS1.11-26 strain shows highly promising potential for further development of an all-round robust yeast strain for efficient fermentation of various lignocellulose hydrolysates.

Development of a D-xylose fermenting and inhibitor tolerant industrial Saccharomyces cerevisiae strain with high performance in lignocellulose hydrolysates using metabolic and evolutionary engineering

PubMed Central

2013-01-01

Background The production of bioethanol from lignocellulose hydrolysates requires a robust, D-xylose-fermenting and inhibitor-tolerant microorganism as catalyst. The purpose of the present work was to develop such a strain from a prime industrial yeast strain, Ethanol Red, used for bioethanol production. Results An expression cassette containing 13 genes including Clostridium phytofermentans XylA, encoding D-xylose isomerase (XI), and enzymes of the pentose phosphate pathway was inserted in two copies in the genome of Ethanol Red. Subsequent EMS mutagenesis, genome shuffling and selection in D-xylose-enriched lignocellulose hydrolysate, followed by multiple rounds of evolutionary engineering in complex medium with D-xylose, gradually established efficient D-xylose fermentation. The best-performing strain, GS1.11-26, showed a maximum specific D-xylose consumption rate of 1.1 g/g DW/h in synthetic medium, with complete attenuation of 35 g/L D-xylose in about 17 h. In separate hydrolysis and fermentation of lignocellulose hydrolysates of Arundo donax (giant reed), spruce and a wheat straw/hay mixture, the maximum specific D-xylose consumption rate was 0.36, 0.23 and 1.1 g/g DW inoculum/h, and the final ethanol titer was 4.2, 3.9 and 5.8% (v/v), respectively. In simultaneous saccharification and fermentation of Arundo hydrolysate, GS1.11-26 produced 32% more ethanol than the parent strain Ethanol Red, due to efficient D-xylose utilization. The high D-xylose fermentation capacity was stable after extended growth in glucose. Cell extracts of strain GS1.11-26 displayed 17-fold higher XI activity compared to the parent strain, but overexpression of XI alone was not enough to establish D-xylose fermentation. The high D-xylose consumption rate was due to synergistic interaction between the high XI activity and one or more mutations in the genome. The GS1.11-26 had a partial respiratory defect causing a reduced aerobic growth rate. Conclusions An industrial yeast strain for bioethanol production with lignocellulose hydrolysates has been developed in the genetic background of a strain widely used for commercial bioethanol production. The strain uses glucose and D-xylose with high consumption rates and partial cofermentation in various lignocellulose hydrolysates with very high ethanol yield. The GS1.11-26 strain shows highly promising potential for further development of an all-round robust yeast strain for efficient fermentation of various lignocellulose hydrolysates. PMID:23800147

Co-consumption of sugars or ethanol and glucose in a Saccharomyces cerevisiae strain deleted in the HXK2 gene.

PubMed

Raamsdonk, L M; Diderich, J A; Kuiper, A; van Gaalen, M; Kruckeberg, A L; Berden, J A; Van Dam, K; Kruckberg, A L

2001-08-01

In previous studies it was shown that deletion of the HXK2 gene in Saccharomyces cerevisiae yields a strain that hardly produces ethanol and grows almost exclusively oxidatively in the presence of abundant glucose. This paper reports on physiological studies on the hxk2 deletion strain on mixtures of glucose/sucrose, glucose/galactose, glucose/maltose and glucose/ethanol in aerobic batch cultures. The hxk2 deletion strain co-consumed galactose and sucrose, together with glucose. In addition, co-consumption of glucose and ethanol was observed during the early exponential growth phase. In S.cerevisiae, co-consumption of ethanol and glucose (in the presence of abundant glucose) has never been reported before. The specific respiration rate of the hxk2 deletion strain growing on the glucose/ethanol mixture was 900 micromol.min(-1).(g protein)(-1), which is four to five times higher than that of the hxk2 deletion strain growing oxidatively on glucose, three times higher than its parent growing on ethanol (when respiration is fully derepressed) and is almost 10 times higher than its parent growing on glucose (when respiration is repressed). This indicates that the hxk2 deletion strain has a strongly enhanced oxidative capacity when grown on a mixture of glucose and ethanol. Copyright 2001 John Wiley & Sons, Ltd.

[Taxation of traditional rums in French overseas territories and public health: The example of Reunion Island].

PubMed

Mété, D

2017-11-01

France has a complex system for the taxation of alcoholic beverages. In the French overseas territories (FOT), the system includes little-known specificities whose purpose is to preserve the sugar-cane-rum sector, a pillar for the weak economies in these territories. Taxes are reduced for traditional rums produced and sold locally. This favors the marketing of alcoholic spirits at low prices. In metropolitan France, on the contrary, spirits are heavily taxed drinks and their share in consumption is minor. Reunion Island (RI) is a FOT confronted with significant socioeconomic precariousness and with one of the highest national morbidity and mortality rates associated with alcohol abuse. Spirits account for half of the total consumption of pure alcohol, with a strong predominance for local traditional rums. These products are preferentially consumed by vulnerable subjects, often affected by an alcohol-use disorder. This study consists of three parts. First, a comparative analysis of alcoholic beverage prices between RI and mainland France. Second, an analysis of the bibliography on the consequences of preferential consumption of spirits. Third, a literature review on the impact of taxation on alcohol-related morbidity and mortality. In France, the cheapest gram of pure alcohol is found in the FOT. The preferential consumption of spirits is associated with more frequent and more rapid complications. It is correlated with the level of alcoholic psychoses. Taxation is effective in reducing damage caused by the abuse of alcoholic beverages. The World Health Organization recommends the application of a minimum price for alcohol and tax increases. The reduced taxation of the traditional rums of the FOT does not take into account public health data. Its purpose is economic. In RI, it contributes to a high level of consumption of spirits and encourages excess mortality through alcohol abuse. It constitutes an inequality of health for these populations. Changes in this tax system is desirable in order to reduce the harm caused by alcohol. It should be closer to the tax system in force in metropolitan France. Alcohol lobbies and lack of political courage have so far inhibited this change to the detriment of the health of the populations. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Difference in Degradation Patterns on Inulin-type Fructans among Strains of Lactobacillus delbrueckii and Lactobacillus paracasei.

PubMed

Tsujikawa, Yuji; Nomoto, Ryohei; Osawa, Ro

2013-01-01

Lactobacillus delbrueckii strains were assessed for their degradation patterns of various carbohydrates with specific reference to inulin-type fructans in comparison with those of Lactobacillus paracasei strains. Firstly, growth curves on glucose, fructose, sucrose and inulin-type fructans with increasing degrees of fructose polymerization (i.e., 1-kestose, fructo-oligosaccharides and inulin) of the strains were compared. L. paracasei DSM 20020 grew well on all these sugars, while the growth rates of the 4 L. delbrueckii strains were markedly higher on the fructans with a greater degree of polymerization than on fructose and sucrose. Secondly, sugar compositions of spent cultures of the strains of L. delbrueckii and L. paracasei grown in mMRS containing either the fructans or inulin were determined by thin layer chromatography, in which the spent cultures of L. paracasei DSM 20020 showed spots of short fructose and sucrose fractions, whereas those of the L. delbrueckii strains did not show such spots at all. These results suggest that, unlike the L. paracasei strains, the L. delbrueckii strains do not degrade the inulin-type fructans extracellularly, but transport the fructans capable of greater polymerization preferentially into their cells to be degraded intracellularly for their growth.

Difference in Degradation Patterns on Inulin-type Fructans among Strains of Lactobacillus delbrueckii and Lactobacillus paracasei

PubMed Central

TSUJIKAWA, Yuji; NOMOTO, Ryohei; OSAWA, Ro

2013-01-01

Lactobacillus delbrueckii strains were assessed for their degradation patterns of various carbohydrates with specific reference to inulin-type fructans in comparison with those of Lactobacillus paracasei strains. Firstly, growth curves on glucose, fructose, sucrose and inulin-type fructans with increasing degrees of fructose polymerization (i.e., 1-kestose, fructo-oligosaccharides and inulin) of the strains were compared. L. paracasei DSM 20020 grew well on all these sugars, while the growth rates of the 4 L. delbrueckii strains were markedly higher on the fructans with a greater degree of polymerization than on fructose and sucrose. Secondly, sugar compositions of spent cultures of the strains of L. delbrueckii and L. paracasei grown in mMRS containing either the fructans or inulin were determined by thin layer chromatography, in which the spent cultures of L. paracasei DSM 20020 showed spots of short fructose and sucrose fractions, whereas those of the L. delbrueckii strains did not show such spots at all. These results suggest that, unlike the L. paracasei strains, the L. delbrueckii strains do not degrade the inulin-type fructans extracellularly, but transport the fructans capable of greater polymerization preferentially into their cells to be degraded intracellularly for their growth. PMID:24936375

Taxonomy of Probiotic Microorganisms

NASA Astrophysics Data System (ADS)

Felis, Giovanna E.; Dellaglio, Franco; Torriani, Sandra

When referring to probiotics, one refers to probiotic strains, i.e., the microbial individuals, sub-cultures of billion of almost identical cells ideally derived from the same mother cell. Therefore, beneficial effects attributed to probiotics are ascribed in fact to specific strains. However, these strains have to be, by law, clearly identified at the species level (Pineiro and Stanton, 2007). In fact, probiotics have to be safe for consumption, and the evaluation of QPS - qualified presumption of safety - status by the European Food Safety Authority (EFSA) (Opinion, 2007) is discussed for species, not for single strains.

Conversion at large intergenic regions of mitochondrial DNA in Saccharomyces cerevisiae.

PubMed

Skelly, P J; Clark-Walker, G D

1990-04-01

Saccharomyces cerevisiae mitochondrial DNA deletion mutants have been used to examine whether base-biased intergenic regions of the genome influence mitochondrial biogenesis. One strain (delta 5.0) lacks a 5-kilobase (kb) segment extending from the proline tRNA gene to the small rRNA gene that includes ori1, while a second strain (delta 3.7) is missing a 3.7-kb region between the genes for ATPase subunit 6 and glutamic acid tRNA that encompasses ori7 plus ori2. Growth of these strains on both fermentable and nonfermentable substrates does not differ from growth of the wild-type strain, indicating that the deletable regions of the genome do not play a direct role in the expression of mitochondrial genes. Examination of whether the 5- or 3.7-kb regions influence mitochondrial DNA transmission was undertaken by crossing strains and examining mitochondrial genotypes in zygotic colonies. In a cross between strain delta 5.0, harboring three active ori elements (ori2, ori3, and ori5), and strain delta 3.7, containing only two active ori elements (ori3 and ori5), there is a preferential recovery of the genome containing two active ori elements (37% of progeny) over that containing three active elements (20%). This unexpected result, suggesting that active ori elements do not influence transmission of respiratory-competent genomes, is interpreted to reflect a preferential conversion of the delta 5.0 genome to the wild type (41% of progeny). Supporting evidence for conversion over biased transmission is shown by preferential recovery of a nonparental genome in the progeny of a heterozygous cross in which both parental molecules can be identified by size polymorphisms.

Conversion at large intergenic regions of mitochondrial DNA in Saccharomyces cerevisiae.

PubMed Central

Skelly, P J; Clark-Walker, G D

1990-01-01

Saccharomyces cerevisiae mitochondrial DNA deletion mutants have been used to examine whether base-biased intergenic regions of the genome influence mitochondrial biogenesis. One strain (delta 5.0) lacks a 5-kilobase (kb) segment extending from the proline tRNA gene to the small rRNA gene that includes ori1, while a second strain (delta 3.7) is missing a 3.7-kb region between the genes for ATPase subunit 6 and glutamic acid tRNA that encompasses ori7 plus ori2. Growth of these strains on both fermentable and nonfermentable substrates does not differ from growth of the wild-type strain, indicating that the deletable regions of the genome do not play a direct role in the expression of mitochondrial genes. Examination of whether the 5- or 3.7-kb regions influence mitochondrial DNA transmission was undertaken by crossing strains and examining mitochondrial genotypes in zygotic colonies. In a cross between strain delta 5.0, harboring three active ori elements (ori2, ori3, and ori5), and strain delta 3.7, containing only two active ori elements (ori3 and ori5), there is a preferential recovery of the genome containing two active ori elements (37% of progeny) over that containing three active elements (20%). This unexpected result, suggesting that active ori elements do not influence transmission of respiratory-competent genomes, is interpreted to reflect a preferential conversion of the delta 5.0 genome to the wild type (41% of progeny). Supporting evidence for conversion over biased transmission is shown by preferential recovery of a nonparental genome in the progeny of a heterozygous cross in which both parental molecules can be identified by size polymorphisms. Images PMID:2181277

Anaerobic biotransformation of hexachlorocyclohexane isomers by Dehalococcoides species and an enrichment culture.

PubMed

Bashir, Safdar; Kuntze, Kevin; Vogt, Carsten; Nijenhuis, Ivonne

2018-06-18

The biotransformation of hexachlorocyclohexane isomers (HCH) by two Dehalococcoides mccartyi strains (195 and BTF08) and an enrichment culture was investigated and compared to conversion by the obligate anaerobic strain Clostridium pasteurianum strain DSMZ 525. The D. mccartyi strains preferentially transformed γ-HCH over α-HCH and δ-HCH isomers while β-HCH biotransformation was not significant. In case of the enrichment culture, γ-HCH was preferentially transformed over the δ-HCH, β-HCH and α-HCH isomers. Major observed metabolites in both cases were tetrachlorocyclohexene and as end products monochlorobenzene (MCB) and benzene. Dechlorination of the γ-HCH isomer was linked to an increase in cell numbers for strain 195. γ-HCH transformation was linked to considerable carbon stable isotope fractionation with the enrichment factor ε c  = - 5.5 ± 0.8‰ for D. mccartyi strain 195, ε c  = - 3.1 ± 0.4‰ for the enrichment culture and ε c  = - 4.1 ± 0.6‰ for co-metabolic transformation by C. pasteurianum.

Bioelectrochemical sulphate reduction on batch reactors: Effect of inoculum-type and applied potential on sulphate consumption and pH.

PubMed

Gacitúa, Manuel A; Muñoz, Enyelbert; González, Bernardo

2018-02-01

Microbial electrolysis batch reactor systems were studied employing different conditions, paying attention on the effect that biocathode potential has on pH and system performance, with the overall aim to distinguish sulphate reduction from H 2 evolution. Inocula from pure strains (Desulfovibrio paquesii and Desulfobacter halotolerans) were compared to a natural source conditioned inoculum. The natural inoculum possess the potential for sulphate reduction on serum bottles experiments due to the activity of mutualistic bacteria (Sedimentibacter sp. and Bacteroides sp.) that assist sulphate-reducing bacterial cells (Desulfovibrio sp.) present in the consortium. Electrochemical batch reactors were monitored at two different potentials (graphite-bar cathodes poised at -900 and -400mV versus standard hydrogen electrode) in an attempt to isolate bioelectrochemical sulphate reduction from hydrogen evolution. At -900mV all inocula were able to reduce sulphate with the consortium demonstrating superior performance (SO 4 2- consumption: 25.71gm -2 day -1 ), despite the high alkalinisation of the media. At -400mV only the pure Desulfobacter halotolerans inoculated system was able to reduce sulphate (SO 4 2- consumption: 17.47gm -2 day -1 ) and, in this potential condition, pH elevation was less for all systems, confirming direct (or at least preferential) bioelectrochemical reduction of sulphate over H 2 production. Copyright © 2017 Elsevier B.V. All rights reserved.

Experimental study of vorticity-strain rate interaction in turbulent partially-premixed jet flames using tomographic particle image velocimetry

DOE PAGES

Coriton, Bruno; Frank, Jonathan H.

2016-02-16

In turbulent flows, the interaction between vorticity, ω, and strain rate, s, is considered a primary mechanism for the transfer of energy from large to small scales through vortex stretching. The ω-s coupling in turbulent jet flames is investigated using tomographic particle image velocimetry (TPIV). TPIV provides a direct measurement of the three-dimensional velocity field from which ω and s are determined. The effects of combustion and mean shear on the ω-s interaction are investigated in turbulent partially premixed methane/air jet flames with high and low probabilities of localized extinction as well as in a non-reacting isothermal air jet withmore » Reynolds number of approximately 13,000. Results show that combustion causes structures of high vorticity and strain rate to agglomerate in highly correlated, elongated layers that span the height of the probe volume. In the non-reacting jet, these structures have a more varied morphology, greater fragmentation, and are not as well correlated. The enhanced spatiotemporal correlation of vorticity and strain rate in the stable flame results in stronger ω-s interaction characterized by increased enstrophy and strain-rate production rates via vortex stretching and straining, respectively. The probability of preferential local alignment between ω and the eigenvector of the intermediate principal strain rate, s 2, which is intrinsic to the ω-s coupling in turbulent flows, is larger in the flames and increases with the flame stability. The larger mean shear in the flame imposes a preferential orientation of ω and s 2 tangential to the shear layer. The extensive and compressive principal strain rates, s 1 and s 3, respectively, are preferentially oriented at approximately 45° with respect to the jet axis. As a result, the production rates of strain and vorticity tend to be dominated by instances in which ω is parallel to the s 1¯-s 2¯ plane and orthogonal to s 3¯.« less

Large-Scale 13C Flux Profiling Reveals Conservation of the Entner-Doudoroff Pathway as a Glycolytic Strategy among Marine Bacteria That Use Glucose

PubMed Central

Klingner, Arne; Bartsch, Annekathrin; Dogs, Marco; Wagner-Döbler, Irene; Jahn, Dieter; Simon, Meinhard; Brinkhoff, Thorsten; Becker, Judith

2015-01-01

Marine bacteria form one of the largest living surfaces on Earth, and their metabolic activity is of fundamental importance for global nutrient cycling. Here, we explored the largely unknown intracellular pathways in 25 microbes representing different classes of marine bacteria that use glucose: Alphaproteobacteria, Gammaproteobacteria, and Flavobacteriia of the Bacteriodetes phylum. We used 13C isotope experiments to infer metabolic fluxes through their carbon core pathways. Notably, 90% of all strains studied use the Entner-Doudoroff (ED) pathway for glucose catabolism, whereas only 10% rely on the Embden-Meyerhof-Parnas (EMP) pathway. This result differed dramatically from the terrestrial model strains studied, which preferentially used the EMP pathway yielding high levels of ATP. Strains using the ED pathway exhibited a more robust resistance against the oxidative stress typically found in this environment. An important feature contributing to the preferential use of the ED pathway in the oceans could therefore be enhanced supply of NADPH through this pathway. The marine bacteria studied did not specifically rely on a distinct anaplerotic route, but the carboxylation of phosphoenolpyruvate (PEP) or pyruvate for fueling of the tricarboxylic acid (TCA) cycle was evenly distributed. The marine isolates studied belong to clades that dominate the uptake of glucose, a major carbon source for bacteria in seawater. Therefore, the ED pathway may play a significant role in the cycling of mono- and polysaccharides by bacterial communities in marine ecosystems. PMID:25616803

Dental caries induction in experimental animals by clinical strains of Streptococcus mutans isolated from Japanese children.

PubMed

Hamada, S; Ooshima, T; Torii, M; Imanishi, H; Masuda, N; Sobue, S; Kotani, S

1978-01-01

Oral implantation and the cariogenic activity of clinical strains of Streptococcus mutans which had been isolated from Japanese children and labeled with streptomycin-resistance were examined in specific pathogen-free Sprague-Dawley rats. All the seven strains tested were easily implanted and persisted during the experimental period. Extensive carious lesions were produced in rats inoculated with clinical strains of S. mutans belonging to serotypes c, d, e, and f, and maintained on caries-inducing diet no. 2000. Noninfected rats did not develop dental caries when fed diet no. 2000. Type d S. mutans preferentially induced smooth surface caries in the rats. Strains of other serotypes primarily developed caries of pit and fissure origin. Caries also developed in rats inoculated with reference S. mutans strains BHTR and FAIR (type b) that had been maintained in the laboratories for many years. However, the cariogenicity of the laboratory strains was found to have decreased markedly. All three S. sanguis strains could be implanted, but only one strain induced definite fissure caries. Two S. salivarius strains could not be implanted well in the rats and therefore they were not cariogenic. Four different species of lactobacilli also failed to induce dental caries in rats subjected to similar caries test regimen on diet no. 200. S. mutans strain MT6R (type c) also induce caries in golden hamsters and ICR mice, but of variable degrees.

Strain-specific variation in a soilborne phytopathogenic fungus for the expression of genes involved in pH signal transduction pathway, pathogenesis and saprophytic survival in response to environmental pH changes.

PubMed

Daval, Stéphanie; Lebreton, Lionel; Gracianne, Cécile; Guillerm-Erckelboudt, Anne-Yvonne; Boutin, Morgane; Marchi, Muriel; Gazengel, Kévin; Sarniguet, Alain

2013-12-01

The soilborne fungus Gaeumannomyces graminis var. tritici (Ggt) causes take-all, a wheat root disease. In an original strain-specific way, a previous study indicates that inside the Ggt species, some strains grow preferentially at acidic pH and other strains at neutral/alkaline pH. The most important mechanism for a fungal response to the environmental pH is the Pal pathway which integrates the products of the six pal genes and the transcription factor PacC. To evaluate whether the Ggt strain-specific growth in function of the ambient pH is mediated via the Pal pathway, a transcriptional study of the genes encoding this pathway was carried out. This study provided the first evidence that the pH signalling pathway similar to those described in other fungi operated in Ggt. The pacC gene was induced at neutral pH whatever the strain. In an original way, the expression of Ggt genes coding for the different Pal proteins depended on the strain and on the ambient pH. In the strain growing better at acidic pH, few pal genes were pH-regulated, and some were overexpressed at neutral pH when regulated. In the strain growing better at neutral pH, underexpression of most of the pal genes at neutral pH occurred. The strains displayed higher gene expression in the ambient pH that unfavoured their growth as if it was a compensation system. All pH taken together, a globally weaker Pal transcript level occurred in the strains that were less sensitive to acidic pH, and on the contrary, the strain growing better on neutral pH showed higher Pal mRNA levels. The expression of genes involved in pathogenesis and saprophytic growth was also regulated by the ambient pH and the strain: each gene displayed a specific pH-regulation that was similar between strains. But all pH taken together, the global transcript levels of four out of six genes were higher in the strain growing better on neutral pH. Altogether, for the first time, the results show that inside a species, conditions affecting environmental pH modulate the expression of genes in an original strain-specific way. Copyright © 2013 Elsevier Inc. All rights reserved.

Preferential acquisition and inoculation of PVYNTN over PVYO in potato by the green peach aphid Myzus persicae (Sulzer)

USDA-ARS?s Scientific Manuscript database

In the past decade, the incidence and distribution of the recombinant, tuber necrotic strain of Potato virus Y (PVYNTN) has been increasing in the U.S. seed potato crop while the ordinary strain (PVYO) has been decreasing. The transmission efficiency of both strains was determined from two potato c...

A Real-Time PCR Assay to Identify and Discriminate Among Wild-Type and Vaccine Strains of Varicella-Zoster Virus and Herpes Simplex Virus in Clinical Specimens, and Comparison With the Clinical Diagnoses

PubMed Central

Harbecke, Ruth; Oxman, Michael N.; Arnold, Beth A.; Ip, Charlotte; Johnson, Gary R.; Levin, Myron J.; Gelb, Lawrence D.; Schmader, Kenneth E.; Straus, Stephen E.; Wang, Hui; Wright, Peter F.; Pachucki, Constance T.; Gershon, Anne A.; Arbeit, Robert D.; Davis, Larry E.; Simberkoff, Michael S.; Weinberg, Adriana; Williams, Heather M.; Cheney, Carol; Petrukhin, Luba; Abraham, Katalin G.; Shaw, Alan; Manoff, Susan; Antonello, Joseph M.; Green, Tina; Wang, Yue; Tan, Charles; Keller, Paul M.

2014-01-01

A real-time PCR assay was developed to identify varicella-zoster virus (VZV) and herpes simplex virus (HSV) DNA in clinical specimens from subjects with suspected herpes zoster (HZ; shingles). Three sets of primers and probes were used in separate PCR reactions to detect and discriminate among wild-type VZV (VZV-WT), Oka vaccine strain VZV (VZV-Oka), and HSV DNA, and the reaction for each virus DNA was multiplexed with primers and probe specific for the human β-globin gene to assess specimen adequacy. Discrimination of all VZV-WT strains, including Japanese isolates and the Oka parent strain, from VZV-Oka was based upon a single nucleotide polymorphism at position 106262 in ORF 62, resulting in preferential amplification by the homologous primer pair. The assay was highly sensitive and specific for the target virus DNA, and no cross-reactions were detected with any other infectious agent. With the PCR assay as the gold standard, the sensitivity of virus culture was 53% for VZV and 77% for HSV. There was 92% agreement between the clinical diagnosis of HZ by the Clinical Evaluation Committee and the PCR assay results. PMID:19475609

Chirality Matters: Synthesis and Consumption of the d-Enantiomer of Lactic Acid by Synechocystis sp. Strain PCC6803

PubMed Central

Angermayr, S. Andreas; Correddu, Danilo; Kern, Ramona; Hagemann, Martin; Hellingwerf, Klaas J.

2015-01-01

Both enantiomers of lactic acid, l-lactic acid and d-lactic acid, can be produced in a sustainable way by a photosynthetic microbial cell factory and thus from CO2, sunlight, and water. Several properties of polylactic acid (a polyester of polymerized lactic acid) depend on the controlled blend of these two enantiomers. Recently, cyanobacterium Synechocystis sp. strain PCC6803 was genetically modified to allow formation of either of these two enantiomers. This report elaborates on the d-lactic acid production achieved by the introduction of a d-specific lactate dehydrogenase from the lactic acid bacterium Leuconostoc mesenteroides into Synechocystis. A typical batch culture of this recombinant strain initially shows lactic acid production, followed by a phase of lactic acid consumption, until production “outcompetes” consumption at later growth stages. We show that Synechocystis is able to use d-lactic acid, but not l-lactic acid, as a carbon source for growth. Deletion of the organism's putative d-lactate dehydrogenase (encoded by slr1556), however, does not eliminate this ability with respect to d-lactic acid consumption. In contrast, d-lactic acid consumption does depend on the presence of glycolate dehydrogenase GlcD1 (encoded by sll0404). Accordingly, this report highlights the need to match a product of interest of a cyanobacterial cell factory with the metabolic network present in the host used for its synthesis and emphasizes the need to understand the physiology of the production host in detail. PMID:26682849

Predicting Alcohol, Cigarette, and Marijuana Use From Preferential Music Consumption.

PubMed

Oberle, Crystal D; Garcia, Javier A

2015-01-01

This study investigated whether use of alcohol, cigarettes, and marijuana may be predicted from preferential consumption of particular music genres. Undergraduates (257 women and 78 men) completed a questionnaire assessing these variables. Partial correlation analyses, controlling for sensation-seeking tendencies and behaviors, revealed that listening to conventional music (pop, country, and religious genres) was negatively correlated with cigarette smoking (p=.001) and marijuana use (p<.001). Additionally, listening to energetic music (rap or hip-hop and soul or funk genres) was positively correlated with marijuana use (p=.004). The only significant predictor of alcohol use was country music, with which it was positively correlated (p=.04). This research suggests an especially harmful influence of energetic music on marijuana use. © The Author(s) 2015.

Lactobacillus plantarum Strains Can Enhance Human Mucosal and Systemic Immunity and Prevent Non-steroidal Anti-inflammatory Drug Induced Reduction in T Regulatory Cells

PubMed Central

de Vos, Paul; Mujagic, Zlatan; de Haan, Bart J.; Siezen, Roland J.; Bron, Peter A.; Meijerink, Marjolein; Wells, Jerry M.; Masclee, Ad A. M.; Boekschoten, Mark V.; Faas, Marijke M.; Troost, Freddy J.

2017-01-01

Orally ingested bacteria interact with intestinal mucosa and may impact immunity. However, insights in mechanisms involved are limited. In this randomized placebo-controlled cross-over trial, healthy human subjects were given Lactobacillus plantarum supplementation (strain TIFN101, CIP104448, or WCFS1) or placebo for 7 days. To determine whether L. plantarum can enhance immune response, we compared the effects of three stains on systemic and gut mucosal immunity, by among others assessing memory responses against tetanus toxoid (TT)-antigen, and mucosal gene transcription, in human volunteers during induction of mild immune stressor in the intestine, by giving a commonly used enteropathic drug, indomethacin [non-steroidal anti-inflammatory drug (NSAID)]. Systemic effects of the interventions were studies in peripheral blood samples. NSAID was found to induce a reduction in serum CD4+/Foxp3 regulatory cells, which was prevented by L. plantarum TIFN101. T-cell polarization experiments showed L. plantarum TIFN101 to enhance responses against TT-antigen, which indicates stimulation of memory responses by this strain. Cell extracts of the specific L. plantarum strains provoked responses after WCFS1 and TIFN101 consumption, indicating stimulation of immune responses against the specific bacteria. Mucosal immunomodulatory effects were studied in duodenal biopsies. In small intestinal mucosa, TIFN101 upregulated genes associated with maintenance of T- and B-cell function and antigen presentation. Furthermore, L. plantarum TIFN101 and WCFS1 downregulated immunological pathways involved in antigen presentation and shared downregulation of snoRNAs, which may suggest cellular destabilization, but may also be an indicator of tissue repair. Full sequencing of the L. plantarum strains revealed possible gene clusters that might be responsible for the differential biological effects of the bacteria on host immunity. In conclusion, the impact of oral consumption L. plantarum on host immunity is strain dependent and involves responses against bacterial cell components. Some strains may enhance specific responses against pathogens by enhancing antigen presentation and leukocyte maintenance in mucosa. In future studies and clinical settings, caution should be taken in selecting beneficial bacteria as closely related strains can have different effects. Our data show that specific bacterial strains can prevent immune stress induced by commonly consumed painkillers such as NSAID and can have enhancing beneficial effects on immunity of consumers by stimulating antigen presentation and memory responses. PMID:28878772

Masking of antigenic epitopes by antibodies shapes the humoral immune response to influenza

PubMed Central

Zarnitsyna, Veronika I.; Ellebedy, Ali H.; Davis, Carl; Jacob, Joshy; Ahmed, Rafi; Antia, Rustom

2015-01-01

The immune responses to influenza, a virus that exhibits strain variation, show complex dynamics where prior immunity shapes the response to the subsequent infecting strains. Original antigenic sin (OAS) describes the observation that antibodies to the first encountered influenza strain, specifically antibodies to the epitopes on the head of influenza's main surface glycoprotein, haemagglutinin (HA), dominate following infection with new drifted strains. OAS suggests that responses to the original strain are preferentially boosted. Recent studies also show limited boosting of the antibodies to conserved epitopes on the stem of HA, which are attractive targets for a ‘universal vaccine’. We develop multi-epitope models to explore how pre-existing immunity modulates the immune response to new strains following immunization. Our models suggest that the masking of antigenic epitopes by antibodies may play an important role in describing the complex dynamics of OAS and limited boosting of antibodies to the stem of HA. Analysis of recently published data confirms model predictions for how pre-existing antibodies to an epitope on HA decrease the magnitude of boosting of the antibody response to this epitope following immunization. We explore strategies for boosting of antibodies to conserved epitopes and generating broadly protective immunity to multiple strains. PMID:26194761

Determining the safety of enzymes used in animal feed.

PubMed

Pariza, Michael W; Cook, Mark

2010-04-01

The purpose of this paper is to provide guidance for evaluating the safety of enzyme preparations used in animal feed. Feed enzymes are typically added to animal feed to increase nutrient bioavailability by acting on feed components prior to or after consumption, i.e., within the gastrointestinal tract. In contrast, food processing enzymes are generally used during processing and then inactivated or removed prior to consumption. The enzymes used in both applications are almost always impure mixtures of active enzyme and other metabolites from the production strain, hence similar safety evaluation procedures for both are warranted. We propose that the primary consideration should be the safety of the production strain and that the decision tree mechanism developed previously for food processing enzymes (Pariza and Johnson, 2001) is appropriate for determining the safety of feed enzymes. Thoroughly characterized non-pathogenic, non-toxigenic microbial strains with a history of safe use in enzyme manufacture are also logical candidates for generating safe strain lineages, from which additional strains may be derived via genetic modification by traditional and non-traditional strategies. For new feed enzyme products derived from a safe strain lineage, it is important to ensure a sufficiently high safety margin for the intended use, and that the product complies with appropriate specifications for chemical and microbial contamination. Copyright 2009 Elsevier Inc. All rights reserved.

Bioluminescence imaging of a tumor-selective, thymidine kinase-defective vaccinia virus Guang9 strain after intratumoral or intraperitoneal administration in mice

PubMed Central

Ding, Yuedi; Fan, Jun; Deng, Lili; Peng, Ying; Zhang, Jue; Huang, Biao

2017-01-01

Vaccinia virus has been used as an oncolytic virus because of its capacity to preferentially infect tumors rather than normal tissues. The vaccinia Tian Tan strain, used as a vaccine against smallpox for millions of people in China, is a promising candidate for cancer therapy. In this study, we constructed an attenuated Tian Tan strain of Guang9 with a disrupted thymidine kinase gene to enhance tumor selectivity and an inserted firefly luciferase to monitor the viral distribution by in vivo bioluminescence imaging. Living animal imaging confirmed the high specificity of vaccinia Guang9 for tumor targeting after intratumoral and intraperitoneal administration. In addition, the vaccinia Guang9 strain produced higher in vivo luciferase activity and endured longer in immunocompromised nude mice than in immunocompetent C57BL/6 mice, all of which had been tumor-challenged. The luciferase activity and viral titers in excised tissues confirmed these conclusions. These data provide evidence for the safety and efficacy of the clinical application of vaccinia virus, which would be a promising approach for cancer therapy. PMID:29179469

Comparative study of sugar fermentation and protein expression patterns of two Lactobacillus plantarum strains grown in three different media.

PubMed

Plumed-Ferrer, Carme; Koistinen, Kaisa M; Tolonen, Tiina L; Lehesranta, Satu J; Kärenlampi, Sirpa O; Mäkimattila, Elina; Joutsjoki, Vesa; Virtanen, Vesa; von Wright, Atte

2008-09-01

A comparative study of two strains of Lactobacillus plantarum (REB1 and MLBPL1) grown in commercial medium (MRS broth), cucumber juice, and liquid pig feed was performed to explore changes to the metabolic pathways of these bacteria, using a proteomics approach (two-dimensional electrophoresis and liquid chromatography-tandem mass spectrometry) combined with analyses of fermentable sugars and fermentation end products. The protein expression showed that even with an excess of glucose in all media, both strains could metabolize different carbohydrates simultaneously and that hexoses could also be used via a phosphoketolase pathway with preferential expression in liquid feed. Sugar analyses showed that the fermentation of sugars was homolactic for all media, with some heterolactic activity in liquid feed, as shown by the production of acetate. Cucumber juice (the medium with the highest glucose content) showed the lowest hexose consumption (10%), followed by liquid feed (33%) and MRS broth (50%). However, bacterial growth was significantly higher in cucumber juice and liquid feed than in MRS broth. This discrepancy was due to the growth benefit obtained from the utilization of the malate present in cucumber juice and liquid feed. Despite different growth conditions, the synthesis of essential cellular components and the stress response of the bacteria were unaffected. This study has improved our understanding of the mechanisms involved in the growth performance of an appropriate lactic acid bacterium strain to be used for food and feed fermentation, information that is of crucial importance to obtain a high-quality fermented product.

Generation of a Listeria vaccine strain by enhanced Caspase-1 activation

PubMed Central

Warren, Sarah E.; Duong, Hien; Mao, Dat Phat; Armstrong, Abraham; Rajan, Jayant; Miao, Edward A.; Aderem, Alan

2012-01-01

The immunostimulatory properties conferred by vaccine adjuvants require Caspase-1 for processing of IL-1β and IL-18. Caspase-1 is activated in response to a breach of the cytosolic compartment by microbes and the process is initiated by intracellular pattern recognition receptors within inflammasomes. Listeria monocytogenes is detected in the cytosol by the NLRC4, NLRP3 and AIM2 inflammasomes. NLRC4 is activated by flagellin, and L. monocytogenes evades this detector by repressing flagellin expression. We generated an L. monocytogenes strain that was forced to express flagellin in the host cell cytosol. This strain hyperactivated Caspase-1 and was preferentially cleared via NLRC4 detection in an IL-1β/IL-18 independent manner. We also created a strain of L. monocytogenes with forced expression of another NLRC4 agonist, PrgJ from the Type III secretion system of S. typhimurium. Forced expression of flagellin or PrgJ resulted in attenuation, yet both strains conferred protective immunity in mice against lethal challenge with L. monocytogenes. This work is the first demonstration of specific targeting of the Caspase-1 activation pathway to generate a safe and potent L. monocytogenes based vaccine. Moreover, the attenuated strains with embedded flagellin or PrgJ adjuvants, represent attractive vectors for vaccines aimed at eliciting T cell responses. PMID:21538346

Serotypes of Vibrio cholerae non-O1 isolated from water supplies for human consumption in Campeche, México and their antibiotic susceptibility pattern.

PubMed

Isaac-Márquez, A P; Lezama-Dávila, C M; Eslava-Campos, C; Navarro-Ocaña, A; Cravioto-Quintana, A

1998-01-01

The presence of Vibrio cholerae non-O1 in water supplies for human consumption in the city of Campeche and rural locality of Bécal was investigated. V. cholerae non-O1 was detected in 5.9% of the samples obtained in deep pools of Campeche. Studies conducted in Bécal and neighbourhood of Morelos in Campeche indicated that collected samples harbored V. cholerae non-O1 in 31.5% and 8.7% respectively. There was a particular pattern of distribution of V. cholerae non-O1 serotypes among different studied regions. Accordingly, V. cholerae non-O1 serotype O14 predominated in the deep pools of Campeche and together with V. cholerae non-O1, O155 were preferentially founds in samples taken from intradomiciliary faucets in the neighbourhood of Morelos. Samples from Bécal predominantly presented the serotype O112. 60% and 53.8% of all studied strains of V. cholerae non-O1 proved to be resistant to ampicillin and carbenicillin. 3.1%, 7.7% and 6.2% presented resistant to doxycycline, trimethoprim-sulfamethoxazole and erythromycin respectively. The study showed the necessity of performing a strong epidemiologic surveillance for emergence and distribution of V. cholerae non-O1.

Autochthonous fermentation starters for the industrial production of Negroamaro wines.

PubMed

Tristezza, Mariana; Vetrano, Cosimo; Bleve, Gianluca; Grieco, Francesco; Tufariello, Maria; Quarta, Angela; Mita, Giovanni; Spano, Giuseppe; Grieco, Francesco

2012-01-01

The aim of the present study was to establish a new procedure for the oenological selection of Saccharomyces cerevisiae strains isolated from natural must fermentations of an important Italian grape cultivar, denoted as "Negroamaro". For this purpose, 108 S. cerevisiae strains were selected as they did not produce H(2)S and then assayed by microfermentation tests. The adopted procedure made it possible to identify 10 strains that were low producers of acetic acid and hydrogen sulphide and showed that they completed sugar consumption during fermentation. These strains were characterized for their specific oenological and technological properties and, two of them, strains 6993 and 6920, are good candidates as industrial starter cultures. A novel protocol was set up for their biomass production and they were employed for industrial-scale fermentation in two industrial cellars. The two strains successfully dominated the fermentation process and contributed to increasing the wines' organoleptic quality. The proposed procedure could be very effective for selecting "company-specific" yeast strains, ideal for the production of typical regional wines. "Winery" starter cultures could be produced on request in a small plant just before or during the vintage season and distributed as a fresh liquid concentrate culture.

Transcriptional analysis of murine macrophages infected with different Toxoplasma strains identifies novel regulation of host signaling pathways.

PubMed

Melo, Mariane B; Nguyen, Quynh P; Cordeiro, Cynthia; Hassan, Musa A; Yang, Ninghan; McKell, Renée; Rosowski, Emily E; Julien, Lindsay; Butty, Vincent; Dardé, Marie-Laure; Ajzenberg, Daniel; Fitzgerald, Katherine; Young, Lucy H; Saeij, Jeroen P J

2013-01-01

Most isolates of Toxoplasma from Europe and North America fall into one of three genetically distinct clonal lineages, the type I, II and III lineages. However, in South America these strains are rarely isolated and instead a great variety of other strains are found. T. gondii strains differ widely in a number of phenotypes in mice, such as virulence, persistence, oral infectivity, migratory capacity, induction of cytokine expression and modulation of host gene expression. The outcome of toxoplasmosis in patients is also variable and we hypothesize that, besides host and environmental factors, the genotype of the parasite strain plays a major role. The molecular basis for these differences in pathogenesis, especially in strains other than the clonal lineages, remains largely unexplored. Macrophages play an essential role in the early immune response against T. gondii and are also the cell type preferentially infected in vivo. To determine if non-canonical Toxoplasma strains have unique interactions with the host cell, we infected murine macrophages with 29 different Toxoplasma strains, representing global diversity, and used RNA-sequencing to determine host and parasite transcriptomes. We identified large differences between strains in the expression level of known parasite effectors and large chromosomal structural variation in some strains. We also identified novel strain-specifically regulated host pathways, including the regulation of the type I interferon response by some atypical strains. IFNβ production by infected cells was associated with parasite killing, independent of interferon gamma activation, and dependent on endosomal Toll-like receptors in macrophages and the cytoplasmic receptor retinoic acid-inducible gene 1 (RIG-I) in fibroblasts.

Effect of oxygenation and temperature on glucose-xylose fermentation in Kluyveromyces marxianus CBS712 strain

PubMed Central

2014-01-01

Background The yeast Kluyveromyces marxianus features specific traits that render it attractive for industrial applications. These include production of ethanol which, together with thermotolerance and the ability to grow with a high specific growth rate on a wide range of substrates, could make it an alternative to Saccharomyces cerevisiae as an ethanol producer. However, its ability to co-ferment C5 and C6 sugars under oxygen-limited conditions is far from being fully characterized. Results In the present study, K. marxianus CBS712 strain was cultivated in defined medium with glucose and xylose as carbon source. Ethanol fermentation and sugar consumption of CBS712 were investigated under different oxygen supplies (1.75%, 11.00% and 20.95% of O2) and different temperatures (30°C and 41°C). By decreasing oxygen supply, independently from the temperature, both biomass production as well as sugar utilization rate were progressively reduced. In all the tested conditions xylose consumption followed glucose exhaustion. Therefore, xylose metabolism was mainly affected by oxygen depletion. Loss in cell viability cannot explain the decrease in sugar consumption rates, as demonstrated by single cell analyses, while cofactor imbalance is commonly considered as the main cause of impairment of the xylose reductase (KmXR) - xylitol dehydrogenase (KmXDH) pathway. Remarkably, when these enzyme activities were assayed in vitro, a significant decrease was observed together with oxygen depletion, not ascribed to reduced transcription of the corresponding genes. Conclusions In the present study both oxygen supply and temperature were shown to be key parameters affecting the fermentation capability of sugars in the K. marxianus CBS712 strain. In particular, a direct correlation was observed between the decreased efficiency to consume xylose with the reduced specific activity of the two main enzymes (KmXR and KmXDH) involved in its catabolism. These data suggest that, in addition to the impairment of the oxidoreductive pathway being determined by the cofactor imbalance, post-transcriptional and/or post-translational regulation of the pathway enzymes contributes to the efficiency of xylose catabolism in micro-aerobic conditions. Overall, the presented work provides novel information on the fermentation capability of the CBS712 strain that is currently considered as the reference strain of the genus K. marxianus. PMID:24712908

Effect of oxygenation and temperature on glucose-xylose fermentation in Kluyveromyces marxianus CBS712 strain.

PubMed

Signori, Lorenzo; Passolunghi, Simone; Ruohonen, Laura; Porro, Danilo; Branduardi, Paola

2014-04-08

The yeast Kluyveromyces marxianus features specific traits that render it attractive for industrial applications. These include production of ethanol which, together with thermotolerance and the ability to grow with a high specific growth rate on a wide range of substrates, could make it an alternative to Saccharomyces cerevisiae as an ethanol producer. However, its ability to co-ferment C5 and C6 sugars under oxygen-limited conditions is far from being fully characterized. In the present study, K. marxianus CBS712 strain was cultivated in defined medium with glucose and xylose as carbon source. Ethanol fermentation and sugar consumption of CBS712 were investigated under different oxygen supplies (1.75%, 11.00% and 20.95% of O2) and different temperatures (30°C and 41°C). By decreasing oxygen supply, independently from the temperature, both biomass production as well as sugar utilization rate were progressively reduced. In all the tested conditions xylose consumption followed glucose exhaustion. Therefore, xylose metabolism was mainly affected by oxygen depletion. Loss in cell viability cannot explain the decrease in sugar consumption rates, as demonstrated by single cell analyses, while cofactor imbalance is commonly considered as the main cause of impairment of the xylose reductase (KmXR) - xylitol dehydrogenase (KmXDH) pathway. Remarkably, when these enzyme activities were assayed in vitro, a significant decrease was observed together with oxygen depletion, not ascribed to reduced transcription of the corresponding genes. In the present study both oxygen supply and temperature were shown to be key parameters affecting the fermentation capability of sugars in the K. marxianus CBS712 strain. In particular, a direct correlation was observed between the decreased efficiency to consume xylose with the reduced specific activity of the two main enzymes (KmXR and KmXDH) involved in its catabolism. These data suggest that, in addition to the impairment of the oxidoreductive pathway being determined by the cofactor imbalance, post-transcriptional and/or post-translational regulation of the pathway enzymes contributes to the efficiency of xylose catabolism in micro-aerobic conditions. Overall, the presented work provides novel information on the fermentation capability of the CBS712 strain that is currently considered as the reference strain of the genus K. marxianus.

The surface chemistry of multi-oxide silicates

NASA Astrophysics Data System (ADS)

Oelkers, Eric H.; Golubev, Sergey V.; Chairat, Claire; Pokrovsky, Oleg S.; Schott, Jacques

2009-08-01

The surface chemistry of natural wollastonite, diopside, enstatite, forsterite, and albite in aqueous solutions was characterized using both electrokinetic techniques and surface titrations performed for 20 min in batch reactors. Titrations performed in such reactors allow determination of both proton consumption and metal release from the mineral surface as a function of pH. The compositions, based on aqueous solution analysis, of all investigated surfaces vary dramatically with solution pH. Ca and Mg are preferentially released from the surfaces of all investigated divalent metal silicates at pH less than ˜8.5-10 but preferentially retained relative to silica at higher pH. As such, the surfaces of these minerals are Si-rich and divalent metal poor except in strongly alkaline solutions. The preferential removal of divalent cations from these surfaces is coupled to proton consumption. The number of protons consumed by the preferential removal of each divalent cation is pH independent but depends on the identity of the mineral; ˜1.5 protons are consumed by the preferential removal of each Ca atom from wollastonite, ˜3 protons are consumed by the preferential removal of each Mg or Ca atom from diopside or enstatite, and ˜4 protons are consumed by the preferential removal of each Mg from forsterite. These observations are interpreted to stem from the creation of additional 'internal' adsorption sites by the preferential removal of divalent metal cations which can be coupled to the condensation of partially detached Si. Similarly, Na and Al are preferentially removed from the albite surface at 2 > pH > 11; mass balance calculations suggest that three protons are consumed by the preferential removal of each Al atom from this surface over this entire pH range. Electrokinetic measurements on fresh mineral powders yield an isoelectric point (pH IEP) 2.6, 4.4, 3.0, 4.5, and <1, for wollastonite, diopside, enstatite, forsterite, and albite, respectively, consistent with the predominance of SiO 2 in the surface layer of all of these multi-oxide silicates at acidic pH. Taken together, these observations suggest fundamental differences between the surface chemistry of simple versus multi-oxide minerals including (1) a dependency of the number and identity of multi-oxide silicate surface sites on the aqueous solution composition, and (2) the dominant role of metal-proton exchange reactions on the reactivity of multi-oxide mineral surfaces including their dissolution rate variation with aqueous solution composition.

3Halobacteriovorax isolated from marine water of the Adriatic Sea, Italy, as an effective predator of Vibrio parahaemolyticus, non-O1/O139 V.cholerae, V.vulnificus.

PubMed

Ottaviani, Donatella; Chierichetti, Serena; Angelico, Gabriele; Forte, Claudio; Rocchegiani, Elena; Manuali, Elisabetta; Leoni, Francesca

2018-06-21

To detect marine Bdellovibrio and like organisms (BALOs) able to infect V.parahaemolyticus from seawater of the Adriatic, Italy. To test, prey specificity and predation efficiency of our Halobacteriovorax isolate, named HBXCO1, towards 17 Vibrio and 7 non-Vibrio strains linked to the Adriatic sea, Italy. Double layer agar plating technique was used to enumerate BALOs and to evaluate their prey specificity and predation efficiency. Transmission electron microscopy and 16S rRNA analysis were used to identify them. Means of BALOs counts ranged from 5.0 PFU/ml (March 2017) to 98.6 PFU/ml (August 2016). HBXCO1 had the ability to attack all tested prey strains of V. parahaemolyticus, V. cholerae nonO1/O139 and V. vulnificus, but it did not prey on non-Vibrio strains and V. alginolyticus under the tested conditions. BALOs capable of infecting pathogenic vibrios are naturally present in seawater of the Adriatic, Italy. Isolate HBXCO1 shows prey specificity preferentially for the Vibrio genus and high predatory efficiency towards a wide range of pathogenic strains. The public impact of V.parahaemolyticus, non O1/O139 V.cholerae and V.vulnificus in bivalves is relevant and current decontamination processes are not always effective. We believe that the predator HBXCO1 represents a potential candidate for the development of strategies of biocontrol of pathogenic vibrios in bivalves from harvesting to trade. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Exposure to Glyphosate- and/or Mn/Zn-Ethylene-bis-Dithiocarbamate-Containing Pesticides Leads to Degeneration of γ-Aminobutyric Acid and Dopamine Neurons in Caenorhabditis elegans

PubMed Central

Negga, Rekek; Stuart, J Andrew; Machen, Morgan L; Salva, Joel; Lizek, Amanda J; Richardson, S Jayne; Osborne, Amanda S; Mirallas, Oriol; McVey, Kenneth A; Fitsanakis, Vanessa A

2011-01-01

Previous studies demonstrate a positive correlation between pesticide usage and Parkinson’s disease (PD), which preferentially targets dopaminergic (DAergic) neurons. In order to examine the potential relationship between two common pesticides and specific neurodegeneration, we chronically (24 hours) or acutely (30 min) exposed two Caenorhabditis elegans (C. elegans) strains to varying concentrations (LC25, LC50 or LC75) of TouchDown® (TD) as per cent active ingredient (glyphosate), or Mancozeb® (MZ) as per cent active ingredient (manganese/zinc ethylene-bis-dithiocarbamate). Furthermore, to more precisely model environmental exposure, worms were also exposed to TD for 30 min, followed by 30-min incubation with varying MZ concentrations. Previous data from out lab suggested general neuronal degeneration using the worm strain NW1229 (pan-neuronal::green fluorescent protein (GFP) construct). To determine whether distinct neuronal groups were preferentially affected, we specifically used EG1285 (GABAergic neurons::GFP construct) and BZ555 (DAergic neurons::GFP construct) worms to verify GABAergic and DAergic neurodegeneration, respectively. Results indicated a statistically significant decrease, when compared to controls (CN), in number of green pixels associated with GABAergic neurons in both chronic (*p < 0.05) and acute (*p < 0.05) treatment paradigms. Analysis of the BZ555 worms indicated a statistically significant decrease (*p < 0.05) in number of green pixels associated with DAergic neurons in both treatment paradigms (chronic and acute) when compared to CN. Taken together, our data suggest that exposure to TD and/or MZ promotes neurodegeneration in both GABAergic and DAergic neurons in the model organism C. elegans. PMID:21922334

Quantitative Metabolomics Reveals an Epigenetic Blueprint for Iron Acquisition in Uropathogenic Escherichia coli

PubMed Central

Henderson, Jeffrey P.; Crowley, Jan R.; Pinkner, Jerome S.; Walker, Jennifer N.; Tsukayama, Pablo; Stamm, Walter E.; Hooton, Thomas M.; Hultgren, Scott J.

2009-01-01

Bacterial pathogens are frequently distinguished by the presence of acquired genes associated with iron acquisition. The presence of specific siderophore receptor genes, however, does not reliably predict activity of the complex protein assemblies involved in synthesis and transport of these secondary metabolites. Here, we have developed a novel quantitative metabolomic approach based on stable isotope dilution to compare the complement of siderophores produced by Escherichia coli strains associated with intestinal colonization or urinary tract disease. Because uropathogenic E. coli are believed to reside in the gut microbiome prior to infection, we compared siderophore production between urinary and rectal isolates within individual patients with recurrent UTI. While all strains produced enterobactin, strong preferential expression of the siderophores yersiniabactin and salmochelin was observed among urinary strains. Conventional PCR genotyping of siderophore receptors was often insensitive to these differences. A linearized enterobactin siderophore was also identified as a product of strains with an active salmochelin gene cluster. These findings argue that qualitative and quantitative epi-genetic optimization occurs in the E. coli secondary metabolome among human uropathogens. Because the virulence-associated biosynthetic pathways are distinct from those associated with rectal colonization, these results suggest strategies for virulence-targeted therapies. PMID:19229321

A novel regio‑specific cyclosporin hydroxylase gene revealed through the genome mining of Pseudonocardia autotrophica.

PubMed

Ban, Jun-Gyu; Woo, Min-Woo; Lee, Bo-Ram; Lee, Mi-Jin; Choi, Si-Sun; Kim, Eung-Soo

2014-05-01

The regio-specific hydroxylation at the 4th N-methyl leucine of the immunosuppressive agent cyclosporin A (CsA) was previously proposed to be mediated by a unique cytochrome P450 hydroxylase (CYP), CYP-sb21 from the rare actinomycetes Sebekia benihana. Interestingly, a different rare actinomycetes species, Pseudonocardia autotrophica, was found to possess a different regio-selectivity, the preferential hydroxylation at the 9th N-methyl leucine of CsA. Through an in silico analysis of the whole genome of P. autotrophica, we describe here the classification of 31 total CYPs in P. autotrophica. Three putative CsA CYP genes, showing the highest sequence homologies with CYPsb21, were successfully inactivated using PCR-targeted gene disruption. Only one knock-out mutant, ΔCYP-pa1, failed to convert CsA to its hydroxylated forms. The hydroxylation activity of CsA by CYP-pa1 was confirmed by CYP-pa1 gene complementation as well as heterologous expression in the CsA non-hydroxylating Streptomyces coelicolor. Moreover, the cyclosporine regio-selectivity of CYP-pa1 expressed in the ΔCYP-sb21 S. benihana mutant strain was also confirmed unchanged through cross complementation. These results show that preferential regio-specific hydroxylation at the 9th N-methyl leucine of CsA is carried out by a specific P450 hydroxylase gene in P. autotrophica, CYP-pa1, setting the stage for the biotechnological application of CsA regioselective hydroxylation.

Glucose consumption rate critically depends on redox state in Corynebacterium glutamicum under oxygen deprivation.

PubMed

Tsuge, Yota; Uematsu, Kimio; Yamamoto, Shogo; Suda, Masako; Yukawa, Hideaki; Inui, Masayuki

2015-07-01

Rapid sugar consumption is important for the microbial production of chemicals and fuels. Here, we show that overexpression of the NADH dehydrogenase gene (ndh) increased glucose consumption rate in Corynebacterium glutamicum under oxygen-deprived conditions through investigating the relationship between the glucose consumption rate and intracellular NADH/NAD(+) ratio in various mutant strains. The NADH/NAD(+) ratio was strongly repressed under oxygen deprivation when glucose consumption was accelerated by the addition of pyruvate or sodium hydrogen carbonate. Overexpression of the ndh gene in the wild-type strain under oxygen deprivation decreased the NADH/NAD(+) ratio from 0.32 to 0.13, whereas the glucose consumption rate increased by 27%. Similarly, in phosphoenolpyruvate carboxylase gene (ppc)- or malate dehydrogenase gene (mdh)-deficient strains, overexpression of the ndh gene decreased the NADH/NAD(+) ratio from 1.66 to 0.37 and 2.20 to 0.57, respectively, whereas the glucose consumption rate increased by 57 and 330%, respectively. However, in a lactate dehydrogenase gene (L-ldhA)-deficient strain, although the NADH/NAD(+) ratio decreased from 5.62 to 1.13, the glucose consumption rate was not markedly altered. In a tailored D-lactate-producing strain, which lacked ppc and L-ldhA genes, but expressed D-ldhA from Lactobacillus delbrueckii, overexpression of the ndh gene decreased the NADH/NAD(+) ratio from 1.77 to 0.56, and increased the glucose consumption rate by 50%. Overall, the glucose consumption rate was found to be inversely proportional to the NADH/NAD(+) ratio in C. glutamicum cultured under oxygen deprivation. These findings could provide an option to increase the productivity of chemicals and fuels under oxygen deprivation.

Pyramidal dislocation induced strain relaxation in hexagonal structured InGaN/AlGaN/GaN multilayer

NASA Astrophysics Data System (ADS)

Yan, P. F.; Du, K.; Sui, M. L.

2012-10-01

Due to the special dislocation slip systems in hexagonal lattice, dislocation dominated deformations in hexagonal structured multilayers are significantly different from that in cubic structured systems. In this work, we have studied the strain relaxation mechanism in hexagonal structured InGaN/AlGaN/GaN multilayers with transmission electron microscopy. Due to lattice mismatch, the strain relaxation was found initiated with the formation of pyramidal dislocations. Such dislocations locally lie at only one preferential slip direction in the hexagonal lattice. This preferential slip causes a shear stress along the basal planes and consequently leads to dissociation of pyramidal dislocations and operation of the basal plane slip system. The compressive InGaN layers and "weak" AlGaN/InGaN interfaces stimulate the dissociation of pyramidal dislocations at the interfaces. These results enhance the understanding of interactions between dislocations and layer interfaces and shed new lights on deformation mechanism in hexagonal-lattice multilayers.

The relationship between alcohol price and brand choice among underage drinkers: are the most popular alcoholic brands consumed by youth the cheapest?

PubMed

Albers, Alison B; DeJong, William; Naimi, Timothy S; Siegel, Michael; Jernigan, David H

2014-11-01

We examined the influence of price on alcohol brand choice among underage youth. Using a national sample of 1,032 youth, ages 13-20, recruited from a national Internet panel in 2011-2012, we compared differences in mean prices between popular and unpopular brands, examined the association of price and brand popularity using logistic regression, and rank ordered the average price of top brands. Lower brand-specific prices were significantly associated with higher levels of past 30-day consumption prevalence. However, youth did not preferentially consume the cheapest brands. These findings indicate that youth have preferences for certain brands, even if those brands cost more than competing brands. Our study highlights the need for research on the impact of brand-specific alcohol marketing on underage drinking.

Oxidation of methyl halides by the facultative methylotroph strain IMB-1

USGS Publications Warehouse

Schaefer, J.K.; Oremland, R.S.

1999-01-01

Washed cell suspensions of the facultative methylotroph strain IMB-1 grown on methyl bromide (MeBr) were able to consume methyl chloride (MeCl) and methyl iodide (MeI) as well as MeBr. Consumption of >100 ??M MeBr by cells grown on glucose, acetate, or monomethylamine required induction. Induction was inhibited by chloramphenicol. However, cells had a constitutive ability to consume low concentrations (<20 nM) of MeBr. Glucose-grown cells were able to readily oxidize [14C]formaldehyde to 14CO2 but had only a small capacity for oxidation of [14C]methanol. Preincubation of cells with MeBr did not affect either activity, but MeBr-induced cells had a greater capacity for [14C]MeBr oxidation than did cells without preincubation. Consumption of MeBr was inhibited by MeI, and MeCl consumption was inhibited by MeBr. No inhibition of MeBr consumption occurred with methyl fluoride, propyl iodide, dibromomethane, dichloromethane, or difluoromethane, and in addition cells did not oxidize any of these compounds. Cells displayed Michaelis-Menten kinetics for the various methyl halides, with apparent K(s) values of 190, 280, and 6,100 nM for MeBr, MeI, and MeCl, respectively. These results suggest the presence of a single oxidation enzyme system specific for methyl halides (other than methyl fluoride) which runs through formaldehyde to CO2. The ease of induction of methyl halide oxidation in strain IMB-1 should facilitate its mass culture for the purpose of reducing MeBr emissions to the atmosphere from fumigated soils.

Male Killing Spiroplasma Preferentially Disrupts Neural Development in the Drosophila melanogaster Embryo

PubMed Central

Martin, Jennifer; Chong, Trisha; Ferree, Patrick M.

2013-01-01

Male killing bacteria such as Spiroplasma are widespread pathogens of numerous arthropods including Drosophila melanogaster. These maternally transmitted bacteria can bias host sex ratios toward the female sex in order to ‘selfishly’ enhance bacterial transmission. However, little is known about the specific means by which these pathogens disrupt host development in order to kill males. Here we show that a male-killing Spiroplasma strain severely disrupts nervous tissue development in male but not female D. melanogaster embryos. The neuroblasts, or neuron progenitors, form properly and their daughter cells differentiate into neurons of the ventral nerve chord. However, the neurons fail to pack together properly and they produce highly abnormal axons. In contrast, non-neural tissue, such as mesoderm, and body segmentation appear normal during this time, although the entire male embryo becomes highly abnormal during later stages. Finally, we found that Spiroplasma is altogether absent from the neural tissue but localizes within the gut and the epithelium immediately surrounding the neural tissue, suggesting that the bacterium secretes a toxin that affects neural tissue development across tissue boundaries. Together these findings demonstrate the unique ability of this insect pathogen to preferentially affect development of a specific embryonic tissue to induce male killing. PMID:24236124

Increasing anaerobic acetate consumption and ethanol yields in Saccharomyces cerevisiae with NADPH-specific alcohol dehydrogenase.

PubMed

Henningsen, Brooks M; Hon, Shuen; Covalla, Sean F; Sonu, Carolina; Argyros, D Aaron; Barrett, Trisha F; Wiswall, Erin; Froehlich, Allan C; Zelle, Rintze M

2015-12-01

Saccharomyces cerevisiae has recently been engineered to use acetate, a primary inhibitor in lignocellulosic hydrolysates, as a cosubstrate during anaerobic ethanolic fermentation. However, the original metabolic pathway devised to convert acetate to ethanol uses NADH-specific acetylating acetaldehyde dehydrogenase and alcohol dehydrogenase and quickly becomes constrained by limited NADH availability, even when glycerol formation is abolished. We present alcohol dehydrogenase as a novel target for anaerobic redox engineering of S. cerevisiae. Introduction of an NADPH-specific alcohol dehydrogenase (NADPH-ADH) not only reduces the NADH demand of the acetate-to-ethanol pathway but also allows the cell to effectively exchange NADPH for NADH during sugar fermentation. Unlike NADH, NADPH can be freely generated under anoxic conditions, via the oxidative pentose phosphate pathway. We show that an industrial bioethanol strain engineered with the original pathway (expressing acetylating acetaldehyde dehydrogenase from Bifidobacterium adolescentis and with deletions of glycerol-3-phosphate dehydrogenase genes GPD1 and GPD2) consumed 1.9 g liter(-1) acetate during fermentation of 114 g liter(-1) glucose. Combined with a decrease in glycerol production from 4.0 to 0.1 g liter(-1), this increased the ethanol yield by 4% over that for the wild type. We provide evidence that acetate consumption in this strain is indeed limited by NADH availability. By introducing an NADPH-ADH from Entamoeba histolytica and with overexpression of ACS2 and ZWF1, we increased acetate consumption to 5.3 g liter(-1) and raised the ethanol yield to 7% above the wild-type level. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Effect of pH and dilution rate on specific production rate of extra cellular metabolites by Lactobacillus salivarius UCO_979C in continuous culture.

PubMed

Valenzuela, Javier Ferrer; Pinuer, Luis; Cancino, Apolinaria García; Yáñez, Rodrigo Bórquez

2015-08-01

The effect of pH and dilution rate on the production of extracellular metabolites of Lactobacillus salivarius UCO_979 was studied. The experiments were carried out in continuous mode, with chemically defined culture medium at a temperature of 37 °C, 200 rpm agitation and synthetic air flow of 100 ml/min. Ethanol, acetic acid, formic acid, lactic acid and glucose were quantified through HPLC, while exopolysaccharide (EPS) was extracted with ethanol and quantified through the Dubois method. The results showed no linear trends for the specific production of lactic acid, EPS, acetic acid and ethanol, while the specific glucose consumption and ATP production rates showed linear trends. There was a metabolic change of the strain for dilution rates below 0.3 h(-1). The pH had a significant effect on the metabolism of the strain, which was evidenced by a higher specific glucose consumption and increased production of ATP at pH 6 compared with that obtained at pH 7. This work shows not only the metabolic capabilities of L. salivarius UCO_979C, but also shows that it is possible to quantify some molecules associated with its current use as gastrointestinal probiotic, especially regarding the production of organic acids and EPS.

IMPACT OF GENETIC STRAIN ON BODY FAT LOSS, FOOD CONSUMPTION, METABOLISM, VENTILATION, AND MOTOR ACTIVITY IN FREE RUNNING FEMALE RATS

EPA Pesticide Factsheets

Physiologic data associated with different strains of common laboratory rat strains.This dataset is associated with the following publication:Gordon , C., P. Phillips , and A. Johnstone. Impact of Genetic Strain on Body Fat Loss, Food Consumption, Metabolism, Ventilation, and Motor Activity in Free Running Female Rats. PHYSIOLOGY AND BEHAVIOR. Elsevier Science Ltd, New York, NY, USA, 153: 56-63, (2016).

Genetically based population divergence in overwintering energy mobilization in brook charr (Salvelinus fontinalis).

PubMed

Crespel, Amélie; Bernatchez, Louis; Garant, Dany; Audet, Céline

2013-03-01

Investigating the nature of physiological traits potentially related to fitness is important towards a better understanding of how species and/or populations may respond to selective pressures imposed by contrasting environments. In northern species in particular, the ability to mobilize energy reserves to compensate for the low external energy intake during winter is crucial. However, the phenotypic and genetic bases of energy reserve accumulation and mobilization have rarely been investigated, especially pertaining to variation in strategy adopted by different populations. In the present study, we documented variation in several energy reserve variables and estimated their quantitative genetic basis to test the null hypothesis of no difference in variation at those traits among three strains of brook charr (Salvelinus fontinalis) and their reciprocal hybrids. Our results indicate that the strategy of winter energy preparation and mobilization was specific to each strain, whereby (1) domestic fish accumulated a higher amount of energy reserves before winter and kept accumulating liver glycogen during winter despite lower feeding; (2) Laval fish used liver glycogen and lipids during winter and experienced a significant decrease in condition factor; (3) Rupert fish had relatively little energy reserves accumulated at the end of fall and preferentially mobilized visceral fat during winter. Significant heritability for traits related to the accumulation and use of energy reserves was found in the domestic and Laval but not in the Rupert strain. Genetic and phenotypic correlations also varied among strains, which suggested population-specific genetic architecture underlying the expression of these traits. Hybrids showed limited evidence of non-additive effects. Overall, this study provides the first evidence of a genetically based-and likely adaptive-population-specific strategy for energy mobilization related to overwinter survival.

Divergent Requirement of Fc-Fcγ Receptor Interactions for In Vivo Protection against Influenza Viruses by Two Pan-H5 Hemagglutinin Antibodies

PubMed Central

Wang, Shuangshuang; Ren, Huanhuan; Jiang, Wenbo; Chen, Honglin; Hu, Hongxing; Chen, Zhiwei

2017-01-01

ABSTRACT Recent studies have shown that Fc-Fcγ receptor (FcγR) interactions are required for in vivo protection against influenza viruses by broadly reactive anti-hemagglutinin (HA) stem, but not virus strain-specific, anti-receptor binding site (RBS), antibodies (Abs). Since only a few Abs recognizing epitopes in the head region but outside the RBS have been tested against single-challenge virus strains, it remains unknown whether Fc-FcγR interactions are required for in vivo protection by Abs recognizing epitopes outside the RBS and whether the requirement is virus strain specific or epitope specific. In the present study, we therefore investigated the requirements for in vivo protection using two pan-H5 Abs, 65C6 and 100F4. We generated chimeric Abs, 65C6/IgG2a and 100F4/IgG2a, which preferentially engage activating FcγRs, and isogenic forms, 65C6/D265A and 100F4/D265A, which do not bind FcγR. Virus neutralizing activity, binding, antibody-dependent cellular cytotoxicity (ADCC), and in vivo protection of these Abs were compared using three H5 strains, A/Shenzhen/406H/2006 (SZ06), A/chicken/Shanxi/2/2006 (SX06), and A/chicken/Netherlands/14015526/2014 (NE14). We found that all four chimeric Abs bound and neutralized the SZ06 and NE14 strains but poorly inhibited the SX06 strain. 65C6/IgG2a and 100F4/IgG2a, but not 65C6/D265A and 100F4/D265A, mediated ADCC against target cells expressing HA derived from all three virus strains. Interestingly, both 65C6/IgG2a and 65C6/D265A demonstrated comparable protection against all three virus strains in vivo; however, 100F4/IgG2a, but not 100F4/D265A, showed in vivo protection. Thus, we conclude that Fc-FcγR interactions are required for in vivo protection by 100F4, but not by 65C6, and therefore, protection is not virus strain specific but epitope specific. IMPORTANCE Abs play an important role in immune protection against influenza virus infection. Fc-FcγR interactions are required for in vivo protection by broadly neutralizing antistem, but not by virus strain-specific, anti-receptor binding site (RBS), Abs. Whether such interactions are necessary for protection by Abs that recognize epitopes outside RBS is not fully understood. In the present study, we investigated in vivo protection mechanisms against three H5 strains by two pan-H5 Abs, 65C6 and 100F4. We show that although these two Abs have similar neutralizing, binding, and ADCC activities against all three H5 strains in vitro, they have divergent requirements for Fc-FcγR interactions to protect against the three H5 strains in vivo. The Fc-FcγR interactions are required for in vivo protection by 100F4, but not by 65C6. Thus, we conclude that Fc-FcγR interactions for in vivo protection by pan-H5 Abs is not strain specific, but epitope specific. PMID:28331095

Divergent Requirement of Fc-Fcγ Receptor Interactions for In Vivo Protection against Influenza Viruses by Two Pan-H5 Hemagglutinin Antibodies.

PubMed

Wang, Shuangshuang; Ren, Huanhuan; Jiang, Wenbo; Chen, Honglin; Hu, Hongxing; Chen, Zhiwei; Zhou, Paul

2017-06-01

Recent studies have shown that Fc-Fcγ receptor (FcγR) interactions are required for in vivo protection against influenza viruses by broadly reactive anti-hemagglutinin (HA) stem, but not virus strain-specific, anti-receptor binding site (RBS), antibodies (Abs). Since only a few Abs recognizing epitopes in the head region but outside the RBS have been tested against single-challenge virus strains, it remains unknown whether Fc-FcγR interactions are required for in vivo protection by Abs recognizing epitopes outside the RBS and whether the requirement is virus strain specific or epitope specific. In the present study, we therefore investigated the requirements for in vivo protection using two pan-H5 Abs, 65C6 and 100F4. We generated chimeric Abs, 65C6/IgG2a and 100F4/IgG2a, which preferentially engage activating FcγRs, and isogenic forms, 65C6/D265A and 100F4/D265A, which do not bind FcγR. Virus neutralizing activity, binding, antibody-dependent cellular cytotoxicity (ADCC), and in vivo protection of these Abs were compared using three H5 strains, A/Shenzhen/406H/2006 (SZ06), A/chicken/Shanxi/2/2006 (SX06), and A/chicken/Netherlands/14015526/2014 (NE14). We found that all four chimeric Abs bound and neutralized the SZ06 and NE14 strains but poorly inhibited the SX06 strain. 65C6/IgG2a and 100F4/IgG2a, but not 65C6/D265A and 100F4/D265A, mediated ADCC against target cells expressing HA derived from all three virus strains. Interestingly, both 65C6/IgG2a and 65C6/D265A demonstrated comparable protection against all three virus strains in vivo ; however, 100F4/IgG2a, but not 100F4/D265A, showed in vivo protection. Thus, we conclude that Fc-FcγR interactions are required for in vivo protection by 100F4, but not by 65C6, and therefore, protection is not virus strain specific but epitope specific. IMPORTANCE Abs play an important role in immune protection against influenza virus infection. Fc-FcγR interactions are required for in vivo protection by broadly neutralizing antistem, but not by virus strain-specific, anti-receptor binding site (RBS), Abs. Whether such interactions are necessary for protection by Abs that recognize epitopes outside RBS is not fully understood. In the present study, we investigated in vivo protection mechanisms against three H5 strains by two pan-H5 Abs, 65C6 and 100F4. We show that although these two Abs have similar neutralizing, binding, and ADCC activities against all three H5 strains in vitro , they have divergent requirements for Fc-FcγR interactions to protect against the three H5 strains in vivo The Fc-FcγR interactions are required for in vivo protection by 100F4, but not by 65C6. Thus, we conclude that Fc-FcγR interactions for in vivo protection by pan-H5 Abs is not strain specific, but epitope specific. Copyright © 2017 American Society for Microbiology.

Emergence of a Norovirus GII.4 Strain Correlates with Changes in Evolving Blockade Epitopes

PubMed Central

Lindesmith, Lisa C.; Costantini, Verónica; Swanstrom, Jesica; Debbink, Kari; Donaldson, Eric F.; Vinjé, Jan

2013-01-01

The major capsid protein of norovirus GII.4 strains is evolving rapidly, resulting in epidemic strains with altered antigenicity. GII.4.2006 Minerva strains circulated at pandemic levels in 2006 and persisted at lower levels until 2009. In 2009, a new GII.4 variant, GII.4.2009 New Orleans, emerged and since then has become the predominant strain circulating in human populations. To determine whether changes in evolving blockade epitopes correlate with the emergence of the GII.4.2009 New Orleans strains, we compared the antibody reactivity of a panel of mouse monoclonal antibodies (MAbs) against GII.4.2006 and GII.4.2009 virus-like particles (VLPs). Both anti-GII.4.2006 and GII.4.2009 MAbs effectively differentiated the two strains by VLP-carbohydrate ligand blockade assay. Most of the GII.4.2006 MAbs preferentially blocked GII.4.2006, while all of the GII.4.2009 MAbs preferentially blocked GII.4.2009, although 8 of 12 tested blockade MAbs blocked both VLPs. Using mutant VLPs designed to alter predicted antigenic epitopes, binding of seven of the blockade MAbs was impacted by alterations in epitope A, identifying residues 294, 296, 297, 298, 368, and 372 as important antigenic sites in these strains. Convalescent-phase serum collected from a GII.4.2009 outbreak confirmed the immunodominance of epitope A, since alterations of epitope A affected serum reactivity by 40%. These data indicate that the GII.4.2009 New Orleans variant has evolved a key blockade epitope, possibly allowing for at least partial escape from protective herd immunity and provide epidemiological support for the utility of monitoring changes in epitope A in emergent strain surveillance. PMID:23269783

Will the next generation of preferential trade and investment agreements undermine prevention of noncommunicable diseases? A prospective policy analysis of the Trans Pacific Partnership Agreement.

PubMed

Thow, Anne Marie; Snowdon, Wendy; Labonté, Ronald; Gleeson, Deborah; Stuckler, David; Hattersley, Libby; Schram, Ashley; Kay, Adrian; Friel, Sharon

2015-01-01

The Trans Pacific Partnership Agreement (TPPA) is one of a new generation of 'deep' preferential trade and investment agreements that will extend many of the provisions seen in previous agreements. This paper presents a prospective policy analysis of the likely text of the TPPA, with reference to nutrition policy space. Specifically, we analyse how the TPPA may constrain governments' policy space to implement the 'policy options for promoting a healthy diet' in the World Health Organization's Global Action Plan for Prevention and Control of Noncommunicable Diseases (NCDs) 2013-2020. This policy analysis suggests that if certain binding commitments are made under the TPPA, they could constrain the ability of governments to protect nutrition policy from the influence of vested interests, reduce the range of interventions available to actively discourage consumption of less healthy food (and to promote healthy food) and limit governments' capacity to implement these interventions, and reduce resources available for nutrition education initiatives. There is scope to protect policy space by including specific exclusions and/or exceptions during negotiation of trade and investment agreements like the TPPA, and by strengthening global health frameworks for nutrition to enable them to be used as reference during disputes in trade fora. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Genetics of Amino Acid Taste and Appetite.

PubMed

Bachmanov, Alexander A; Bosak, Natalia P; Glendinning, John I; Inoue, Masashi; Li, Xia; Manita, Satoshi; McCaughey, Stuart A; Murata, Yuko; Reed, Danielle R; Tordoff, Michael G; Beauchamp, Gary K

2016-07-01

The consumption of amino acids by animals is controlled by both oral and postoral mechanisms. We used a genetic approach to investigate these mechanisms. Our studies have shown that inbred mouse strains differ in voluntary amino acid consumption, and these differences depend on sensory and nutritive properties of amino acids. Like humans, mice perceive some amino acids as having a sweet (sucrose-like) taste and others as having an umami (glutamate-like) taste. Mouse strain differences in the consumption of some sweet-tasting amino acids (d-phenylalanine, d-tryptophan, and l-proline) are associated with polymorphisms of a taste receptor, type 1, member 3 gene (Tas1r3), and involve differential peripheral taste responsiveness. Strain differences in the consumption of some other sweet-tasting amino acids (glycine, l-alanine, l-glutamine, and l-threonine) do not depend on Tas1r3 polymorphisms and so must be due to allelic variation in other, as yet unknown, genes involved in sweet taste. Strain differences in the consumption of l-glutamate may depend on postingestive rather than taste mechanisms. Thus, genes and physiologic mechanisms responsible for strain differences in the consumption of each amino acid depend on the nature of its taste and postingestive properties. Overall, mouse strain differences in amino acid taste and appetite have a complex genetic architecture. In addition to the Tas1r3 gene, these differences depend on other genes likely involved in determining the taste and postingestive effects of amino acids. The identification of these genes may lead to the discovery of novel mechanisms that regulate amino acid taste and appetite. © 2016 American Society for Nutrition.

Genetics of Amino Acid Taste and Appetite123

PubMed Central

Bosak, Natalia P; Glendinning, John I; Inoue, Masashi; Li, Xia; Manita, Satoshi; McCaughey, Stuart A; Murata, Yuko; Beauchamp, Gary K

2016-01-01

The consumption of amino acids by animals is controlled by both oral and postoral mechanisms. We used a genetic approach to investigate these mechanisms. Our studies have shown that inbred mouse strains differ in voluntary amino acid consumption, and these differences depend on sensory and nutritive properties of amino acids. Like humans, mice perceive some amino acids as having a sweet (sucrose-like) taste and others as having an umami (glutamate-like) taste. Mouse strain differences in the consumption of some sweet-tasting amino acids (d-phenylalanine, d-tryptophan, and l-proline) are associated with polymorphisms of a taste receptor, type 1, member 3 gene (Tas1r3), and involve differential peripheral taste responsiveness. Strain differences in the consumption of some other sweet-tasting amino acids (glycine, l-alanine, l-glutamine, and l-threonine) do not depend on Tas1r3 polymorphisms and so must be due to allelic variation in other, as yet unknown, genes involved in sweet taste. Strain differences in the consumption of l-glutamate may depend on postingestive rather than taste mechanisms. Thus, genes and physiologic mechanisms responsible for strain differences in the consumption of each amino acid depend on the nature of its taste and postingestive properties. Overall, mouse strain differences in amino acid taste and appetite have a complex genetic architecture. In addition to the Tas1r3 gene, these differences depend on other genes likely involved in determining the taste and postingestive effects of amino acids. The identification of these genes may lead to the discovery of novel mechanisms that regulate amino acid taste and appetite. PMID:27422518

Sugar utilization patterns and respiro-fermentative metabolism in the baker's yeast Torulaspora delbrueckii.

PubMed

Alves-Araújo, C; Pacheco, A; Almeida, M J; Spencer-Martins, I; Leão, C; Sousa, M J

2007-03-01

The highly osmo- and cryotolerant yeast species Torulaspora delbrueckii is an important case study among the non-Saccharomyces yeast species. The strain T. delbrueckii PYCC 5321, isolated from traditional corn and rye bread dough in northern Portugal, is considered particularly interesting for the baking industry. This paper reports the sugar utilization patterns of this strain, using media with glucose, maltose and sucrose, alone or in mixtures. Kinetics of growth, biomass and ethanol yields, fermentation and respiration rates, hydrolase activities and sugar uptake rates were used to infer the potential applied relevance of this yeast in comparison to a conventional baker's strain of Saccharomyces cerevisiae. The results showed that both maltase and maltose transport in T. delbrueckii were subject to glucose repression and maltose induction, whereas invertase was subject to glucose control but not dependent on sucrose induction. A comparative analysis of specific sugar consumption rates and transport capacities suggests that the transport step limits both glucose and maltose metabolism. Specific rates of CO(2) production and O(2) consumption showed a significantly higher contribution of respiration to the overall metabolism in T. delbrueckii than in S. cerevisiae. This was reflected in the biomass yields from batch cultures and could represent an asset for the large-scale production of the former species. This work contributes to a better understanding of the physiology of a non-conventional yeast species, with a view to the full exploitation of T. delbrueckii by the baking industry.

Zika virus has oncolytic activity against glioblastoma stem cells

PubMed Central

Gorman, Matthew J.; McKenzie, Lisa D.; Hubert, Christopher G.; Prager, Briana C.; Fernandez, Estefania; Richner, Justin M.; Zhang, Rong; Shan, Chao; Tycksen, Eric; Shi, Pei-Yong

2017-01-01

Glioblastoma is a highly lethal brain cancer that frequently recurs in proximity to the original resection cavity. We explored the use of oncolytic virus therapy against glioblastoma with Zika virus (ZIKV), a flavivirus that induces cell death and differentiation of neural precursor cells in the developing fetus. ZIKV preferentially infected and killed glioblastoma stem cells (GSCs) relative to differentiated tumor progeny or normal neuronal cells. The effects against GSCs were not a general property of neurotropic flaviviruses, as West Nile virus indiscriminately killed both tumor and normal neural cells. ZIKV potently depleted patient-derived GSCs grown in culture and in organoids. Moreover, mice with glioblastoma survived substantially longer and at greater rates when the tumor was inoculated with a mouse-adapted strain of ZIKV. Our results suggest that ZIKV is an oncolytic virus that can preferentially target GSCs; thus, genetically modified strains that further optimize safety could have therapeutic efficacy for adult glioblastoma patients. PMID:28874392

The Role of Hydrophobicity and Surface Receptors at Hyphae of Lyophyllum sp. Strain Karsten in the Interaction with Burkholderia terrae BS001 - Implications for Interactions in Soil.

PubMed

Vila, Taissa; Nazir, Rashid; Rozental, Sonia; Dos Santos, Giulia M P; Calixto, Renata O R; Barreto-Bergter, Eliana; Wick, Lukas Y; van Elsas, Jan Dirk

2016-01-01

The soil bacterium Burkholderia terrae strain BS001 can interact with varying soil fungi, using mechanisms that range from the utilization of carbon/energy sources such as glycerol to the ability to reach novel territories in soil via co-migration with growing fungal mycelia. Here, we investigate the intrinsic properties of the B. terrae BS001 interaction with the basidiomycetous soil fungus Lyophyllum sp. strain Karsten. In some experiments, the ascomycetous Trichoderma asperellum 302 was also used. The hyphae of Lyophyllum sp. strain Karsten were largely hydrophilic on water-containing media versus hydrophobic when aerial, as evidenced by contact angle analyses (CA). Co-migration of B. terrae strain BS001 cells with the hyphae of the two fungi occurred preferentially along the - presumably hydrophilic - soil-dwelling hyphae, whereas aerial hyphae did not allow efficient migration, due to reduced thickness of their surrounding mucous films. Moreover, the cell numbers over the length of the hyphae in soil showed an uneven distribution, i.e., the CFU numbers increased from minima at the inoculation point to maximal numbers in the middle of the extended hyphae, then decreasing toward the terminal side. Microscopic analyses of the strain BS001 associations with the Lyophyllum sp. strain Karsten hyphae in the microcosms confirmed the presence of B. terrae BS001 cells on the mucous matter that was present at the hyphal surfaces of the fungi used. Cell agglomerates were found to accumulate at defined sites on the hyphal surfaces, which were coined 'fungal-interactive' hot spots. Evidence was further obtained for the contention that receptors for a physical bacterium-fungus interaction occur at the Lyophyllum sp. strain Karsten hyphal surface, in which the specific glycosphingolipid ceramide monohexoside (CMH) plays an important role. Thus, bacterial adherence may be mediated by heterogeneously distributed fungal-specific receptors, implying the CMH moieties. This study sheds light on the physical aspects of the B. terrae BS001 - Lyophyllum sp. strain Karsten interaction, highlighting heterogeneity along the hyphae with respect to hydrophobicity and the presence of potential anchoring sites.

The Role of Hydrophobicity and Surface Receptors at Hyphae of Lyophyllum sp. Strain Karsten in the Interaction with Burkholderia terrae BS001 – Implications for Interactions in Soil

PubMed Central

Vila, Taissa; Nazir, Rashid; Rozental, Sonia; dos Santos, Giulia M. P.; Calixto, Renata O. R.; Barreto-Bergter, Eliana; Wick, Lukas Y.; van Elsas, Jan Dirk

2016-01-01

The soil bacterium Burkholderia terrae strain BS001 can interact with varying soil fungi, using mechanisms that range from the utilization of carbon/energy sources such as glycerol to the ability to reach novel territories in soil via co-migration with growing fungal mycelia. Here, we investigate the intrinsic properties of the B. terrae BS001 interaction with the basidiomycetous soil fungus Lyophyllum sp. strain Karsten. In some experiments, the ascomycetous Trichoderma asperellum 302 was also used. The hyphae of Lyophyllum sp. strain Karsten were largely hydrophilic on water-containing media versus hydrophobic when aerial, as evidenced by contact angle analyses (CA). Co-migration of B. terrae strain BS001 cells with the hyphae of the two fungi occurred preferentially along the - presumably hydrophilic - soil-dwelling hyphae, whereas aerial hyphae did not allow efficient migration, due to reduced thickness of their surrounding mucous films. Moreover, the cell numbers over the length of the hyphae in soil showed an uneven distribution, i.e., the CFU numbers increased from minima at the inoculation point to maximal numbers in the middle of the extended hyphae, then decreasing toward the terminal side. Microscopic analyses of the strain BS001 associations with the Lyophyllum sp. strain Karsten hyphae in the microcosms confirmed the presence of B. terrae BS001 cells on the mucous matter that was present at the hyphal surfaces of the fungi used. Cell agglomerates were found to accumulate at defined sites on the hyphal surfaces, which were coined ‘fungal-interactive’ hot spots. Evidence was further obtained for the contention that receptors for a physical bacterium-fungus interaction occur at the Lyophyllum sp. strain Karsten hyphal surface, in which the specific glycosphingolipid ceramide monohexoside (CMH) plays an important role. Thus, bacterial adherence may be mediated by heterogeneously distributed fungal-specific receptors, implying the CMH moieties. This study sheds light on the physical aspects of the B. terrae BS001 – Lyophyllum sp. strain Karsten interaction, highlighting heterogeneity along the hyphae with respect to hydrophobicity and the presence of potential anchoring sites. PMID:27833591

Selective consumption and metabolic allocation of terrestrial and algal carbon determine allochthony in lake bacteria.

PubMed

Guillemette, François; Leigh McCallister, S; Del Giorgio, Paul A

2016-06-01

Here we explore strategies of resource utilization and allocation of algal versus terrestrially derived carbon (C) by lake bacterioplankton. We quantified the consumption of terrestrial and algal dissolved organic carbon, and the subsequent allocation of these pools to bacterial growth and respiration, based on the δ(13)C isotopic signatures of bacterial biomass and respiratory carbon dioxide (CO2). Our results confirm that bacterial communities preferentially remove algal C from the terrestrially dominated organic C pool of lakes, but contrary to current assumptions, selectively allocate this autochthonous substrate to respiration, whereas terrestrial C was preferentially allocated to biosynthesis. The results provide further evidence of a mechanism whereby inputs of labile, algal-derived organic C may stimulate the incorporation of a more recalcitrant, terrestrial C pool. This mechanism resulted in a counterintuitive pattern of high and relatively constant levels of allochthony (~76%) in bacterial biomass across lakes that otherwise differ greatly in productivity and external inputs.

Selective consumption and metabolic allocation of terrestrial and algal carbon determine allochthony in lake bacteria

PubMed Central

Guillemette, François; Leigh McCallister, S; del Giorgio, Paul A

2016-01-01

Here we explore strategies of resource utilization and allocation of algal versus terrestrially derived carbon (C) by lake bacterioplankton. We quantified the consumption of terrestrial and algal dissolved organic carbon, and the subsequent allocation of these pools to bacterial growth and respiration, based on the δ13C isotopic signatures of bacterial biomass and respiratory carbon dioxide (CO2). Our results confirm that bacterial communities preferentially remove algal C from the terrestrially dominated organic C pool of lakes, but contrary to current assumptions, selectively allocate this autochthonous substrate to respiration, whereas terrestrial C was preferentially allocated to biosynthesis. The results provide further evidence of a mechanism whereby inputs of labile, algal-derived organic C may stimulate the incorporation of a more recalcitrant, terrestrial C pool. This mechanism resulted in a counterintuitive pattern of high and relatively constant levels of allochthony (~76%) in bacterial biomass across lakes that otherwise differ greatly in productivity and external inputs. PMID:26623544

NO 2 oxidation reactivity and burning mode of diesel particulates

DOE PAGES

Strzelec, Andrea; Vander Wal, Randy L.; Thompson, Thomas N.; ...

2016-03-24

The NO 2 oxidation kinetics and burning mode for diesel particulate from light-duty and medium-duty engines fueled with either ultra low sulfur diesel or soy methyl ester biodiesel blends have been investigated and are shown to be significantly different from oxidation by O 2. Oxidation kinetics were measured using a flow-through packed bed microreactor for temperature programmed reactions and isothermal differential pulsed oxidation reactions. The burning mode was evaluated using the same reactor system for flowing BET specific surface area measurements and HR-TEM with fringe analysis to evaluate the nanostructure of the nascent and partially oxidized particulates. The low activationmore » energy measured, specific surface area progression with extent of oxidation, HR-TEM images and difference plots of fringe length and tortuosity paint a consistent picture of higher reactivity for NO 2, which reacts indiscriminately immediately upon contact with the surface, leading to the Zone I or shrinking core type oxidation. In comparison, O 2 oxidation is shown to have relatively lower reactivity, preferentially attacking highly curved lamella, which are more reactive due to bond strain, and short lamella, which have a higher proportion of more reactive edge sites. Furthermore, this preferential oxidation leads to Zone II type oxidation, where solid phase diffusion of oxygen via pores contributes significantly to slowing the overall oxidation rate, by comparison.« less

Anaerobic Dehalogenation of Chloroanilines by Dehalococcoides mccartyi Strain CBDB1 and Dehalobacter Strain 14DCB1 via Different Pathways as Related to Molecular Electronic Structure.

PubMed

Zhang, Shangwei; Wondrousch, Dominik; Cooper, Myriel; Zinder, Stephen H; Schüürmann, Gerrit; Adrian, Lorenz

2017-04-04

Dehalococcoides mccartyi strain CBDB1 and Dehalobacter strain 14DCB1 are organohalide-respiring microbes of the phyla Chloroflexi and Firmicutes, respectively. Here, we report the transformation of chloroanilines by these two bacterial strains via dissimilar dehalogenation pathways and discuss the underlying mechanism with quantum chemically calculated net atomic charges of the substrate Cl, H, and C atoms. Strain CBDB1 preferentially removed Cl doubly flanked by two Cl or by one Cl and NH 2 , whereas strain 14DCB1 preferentially dechlorinated Cl that has an ortho H. For the CBDB1-mediated dechlorination, comparative analysis with Hirshfeld charges shows that the least-negative Cl discriminates active from nonactive substrates in 14 out of 15 cases and may represent the preferred site of primary attack through cob(I)alamin. For the latter trend, three of seven active substrates provide strong evidence, with partial support from three of the remaining four substrates. Regarding strain 14DCB1, the most positive carbon-attached H atom discriminates active from nonactive chloroanilines in again 14 out of 15 cases. Here, regioselectivity is governed for 10 of the 11 active substrates by the most positive H attached to the highest-charge (most positive or least negative) aromatic C carrying the Cl to be removed. These findings suggest the aromatic ring H as primary site of attack through the supernucleophile Co(I), converting an initial H bond to a full electron transfer as start of the reductive dehalogenation. For both mechanisms, one- and two-electron transfer to Cl (strain CBDB1) or H (strain 14DCB1) are compatible with the presently available data. Computational chemistry research into reaction intermediates and pathways may further aid in understanding the bacterial reductive dehalogenation at the molecular level.

Oxygen uptake rate in alginate producer (algU+) and nonproducer (algU-) strains of Azotobacter vinelandii under nitrogen-fixation conditions.

PubMed

Castillo, T; López, I; Flores, C; Segura, D; García, A; Galindo, E; Peña, C

2018-07-01

The sigma E (AlgU) in Azotobacter vinelandii has been shown to control the expression of cydR gene, a repressor of genes of the alternative respiratory chain, and alginate has been considered a barrier for oxygen diffusion. Therefore, the aim of the present study was to compare the respiratory activity of an alginate nonproducing strain, lacking the sigma factor E (algU-), and polymer-producing strains (algU+) of A. vinelandii under diazotrophic conditions at different aeration conditions. Our results reveal that under diazotrophic and high aeration conditions, A. vinelandii strain OP (algU-) had a specific oxygen consumption rate higher (30 and 54%) than those observed in the OP algU+-complemented strain, named OPAlgU+, and the ATCC 9046 respectively. However, the specific growth rate and biomass yields (based on oxygen and sucrose) were lower for OP cultivations as compared to the algU+ strains. These differences were partially explained by an increase in 1·5-fold of cydA relative expression in the OP strain, as compared to that obtained in the isogenic OPAlgU+ strain. Overall, our results confirm the important role of algU gene on the regulation of respiratory metabolism under diazotrophic growth when A. vinelandii is exposed to high aeration. This study highlights the role of AlgU to control respiration of A. vinelandii when exposed to diazotrophy. © 2018 The Society for Applied Microbiology.

Process of labeling specific chromosomes using recombinant repetitive DNA

DOEpatents

Moyzis, R.K.; Meyne, J.

1988-02-12

Chromosome preferential nucleotide sequences are first determined from a library of recombinant DNA clones having families of repetitive sequences. Library clones are identified with a low homology with a sequence of repetitive DNA families to which the first clones respectively belong and variant sequences are then identified by selecting clones having a pattern of hybridization with genomic DNA dissimilar to the hybridization pattern shown by the respective families. In another embodiment, variant sequences are selected from a sequence of a known repetitive DNA family. The selected variant sequence is classified as chromosome specific, chromosome preferential, or chromosome nonspecific. Sequences which are classified as chromosome preferential are further sequenced and regions are identified having a low homology with other regions of the chromosome preferential sequence or with known sequences of other family members and consensus sequences of the repetitive DNA families for the chromosome preferential sequences. The selected low homology regions are then hybridized with chromosomes to determine those low homology regions hybridized with a specific chromosome under normal stringency conditions.

A new approach to enhance the selectivity of liberation and the efficiency of coal grinding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, X.H.; Guo, Q.; Parekh, B.K.

1993-12-31

An innovative process has been developed at the University of Kentucky to enhance the liberation of mineral matter from coal and the efficiency of grinding energy utilization. Through treating coal with a swelling agent prior to grinding, the grindability of coals can be considerably improved. The Hardgrove Grindability tests show that the HGI of a KY. No. 9 coal increases from 41 for the untreated coal to 60-90 after swelling pretreatment for a short time. Batch stirred ball mill grinding results demonstrate that this new technique has a great potential in reducing the energy consumption of fine coal grinding. Dependingmore » on the pretreatment conditions, the specific energy consumption of producing less than 10 {mu}m product is reduced to 41-60% of that of the untreated coal feed. The production rate of -10 {mu}m particles increases considerably for the pretreated coal. The Energy-Dispersive-X-ray Analytical Scanning Electron Microscope (EDXA-SEM) studies clearly demonstrate that intensive cracking and fracturing were developed during the swelling pretreatment. Cracks and fractures were induced in the coal matrix, preferentially along the boundaries between the pyrite particles and coal matrix. These may be responsible for enhancement in both the efficiency of grinding energy consumption and the selectivity of liberation.« less

Voltage-impulse-induced dual-range nonvolatile magnetization modulation in metglas/PZT heterostructure

NASA Astrophysics Data System (ADS)

Tang, Xiaoli; Su, Hua; Zhang, Huaiwu; Sun, Nian X.

2016-11-01

Dual-range, nonvolatile magnetization modulation induced by voltage impulses was investigated in the metglas/lead zirconate titanate (PZT) heterostructure at room temperature. The heterostructure was obtained by bonding a square metglas ribbon on the top electrode of the PZT substrate, which contained defect dipoles resulting from acceptor doping. The PZT substrate achieved two strain hysteretic loops with the application of specific voltage impulse excitation modes. Through strain-mediated magnetoelectric coupling between the metglas ribbon and the PZT substrate, two strain hysteretic loops led to a dual-range nonvolatile magnetization modulation in the heterostructure. Reversible and stable voltage-impulse-induced nonvolatile modulation in the ferromagnetic resonance field and magnetic hysteresis characteristics were also realized. This method provides a promising approach in reducing energy consumption in magnetization modulation and other related devices.

Genetics and molecular specificity of sialylation of Histophilus somni lipooligosaccharide (LOS) and the effect of LOS sialylation on Toll-like receptor-4 signaling.

PubMed

Howard, Michael D; Willis, Lisa; Wakarchuk, Warren; St Michael, Frank; Cox, Andrew; Horne, William T; Hontecillas, Raquel; Bassaganya-Riera, Josep; Lorenz, Eva; Inzana, Thomas J

2011-11-21

Histophilus somni is an etiologic agent of bovine respiratory and systemic diseases. Most pathogenic strains of H. somni that have been tested (36 of 42) are able to utilize N-acetyl-5-neuraminic acid (Neu5Ac) to sialylate their lipooligosaccharide (LOS). Homologs of all the genes required for transport, metabolism, and regulation of Neu5Ac in Haemophilus influenzae were identified in the sequenced genomes of H. somni. Three open reading frames (ORFs) in H. somni strain 2336 were identified that contained homology to genes required for LOS sialylation in related bacteria. ORF-1 (hssT-I), ORF-2 (hssT-II), and ORF-3 (neuA(Hs)) were predicted to encode for putative proteins with 37% amino acid homology to an α-(2-3)-sialyltransferase in H. influenzae, 43% amino acid homology to an Haemophilus ducreyi sialyltransferase, and 72% amino acid homology to an H. influenzae CMP-Neu5Ac synthetase, respectively. The specific enzyme activity of each ORF was determined using synthetic acceptor substrates. The HssT-I sialyltransferase primarily sialylated N-acetyllactosamine (LacNAc, Gal-β-[1-4]-GlcNAc-R), which is expressed on strain 2336, whereas HssT-II preferentially sialylated lacto-N-biose (LNB, Gal-β-[1-3]-GlcNAc-R), which is expressed on a phase variant of strain 2336: strain 738. Phase variation of the terminal galactose linkage in strain 738 from β-(1-3)-(LNB) to β-(1-4)-(LacNAc) was confirmed using monoclonal antibody reactivity and nuclear magnetic resonance spectroscopy. Sialylated LOS induced significantly less chemokine response from macrophages derived from Toll-like receptor (TLR)-4 knockout mice than from de-sialylated LOS. Furthermore, sialylated LOS induced significantly less NF-κB activity from mouse-derived bone marrow macrophages than de-sialylated LOS. Therefore, sialylation inhibited LOS signaling through TLR-4. In conclusion, H. somni utilizes linkage-specific sialyltransferases to sialylate its LOS to avoid innate host defense mechanisms despite simultaneous epitope phase variation. Copyright © 2011 Elsevier B.V. All rights reserved.

Preferential Allele Expression Analysis Identifies Shared Germline and Somatic Driver Genes in Advanced Ovarian Cancer

PubMed Central

Halabi, Najeeb M.; Martinez, Alejandra; Al-Farsi, Halema; Mery, Eliane; Puydenus, Laurence; Pujol, Pascal; Khalak, Hanif G.; McLurcan, Cameron; Ferron, Gwenael; Querleu, Denis; Al-Azwani, Iman; Al-Dous, Eman; Mohamoud, Yasmin A.; Malek, Joel A.; Rafii, Arash

2016-01-01

Identifying genes where a variant allele is preferentially expressed in tumors could lead to a better understanding of cancer biology and optimization of targeted therapy. However, tumor sample heterogeneity complicates standard approaches for detecting preferential allele expression. We therefore developed a novel approach combining genome and transcriptome sequencing data from the same sample that corrects for sample heterogeneity and identifies significant preferentially expressed alleles. We applied this analysis to epithelial ovarian cancer samples consisting of matched primary ovary and peritoneum and lymph node metastasis. We find that preferentially expressed variant alleles include germline and somatic variants, are shared at a relatively high frequency between patients, and are in gene networks known to be involved in cancer processes. Analysis at a patient level identifies patient-specific preferentially expressed alleles in genes that are targets for known drugs. Analysis at a site level identifies patterns of site specific preferential allele expression with similar pathways being impacted in the primary and metastasis sites. We conclude that genes with preferentially expressed variant alleles can act as cancer drivers and that targeting those genes could lead to new therapeutic strategies. PMID:26735499

Effect of borides on hot deformation behavior and microstructure evolution of powder metallurgy high borated stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Xuan

To investigate borides effect on the hot deformation behavior and microstructure evolution of powder metallurgy high borated stainless steel, hot compression tests at the temperatures of 950– 1150 °C and the strain rates of 0.01– 10 s{sup −1} were performed. Flow stress curves indicated that borides increased the material's stress level at low temperature but the strength was sacrificed at temperatures above 1100 °C. A hyperbolic-sine equation was used to characterize the dependence of the flow stress on the deformation temperature and strain rate. The hot deformation activation energy and stress exponent were determined to be 355 kJ/mol and 3.2,more » respectively. The main factors leading to activation energy and stress exponent of studied steel lower than those of commercial 304 stainless steel were discussed. Processing maps at the strains of 0.1, 0.3, 0.5, and 0.7 showed that flow instability mainly concentrated at 950– 1150 °C and strain rate higher than 0.6 s{sup −1}. Results of microstructure illustrated that dynamic recrystallization was fully completed at both high temperature-low strain rate and low temperature-high strain rate. In the instability region cracks were generated in addition to cavities. Interestingly, borides maintained a preferential orientation resulting from particle rotation during compression. - Highlights: •The decrement of activation energy was affected by boride and boron solution. •The decrease of stress exponent was influenced by composition and Cottrell atmosphere. •Boride represented a preferential orientation caused by particle rotation.« less

Milk is not just food but most likely a genetic transfection system activating mTORC1 signaling for postnatal growth

PubMed Central

2013-01-01

Milk has been recognized to represent a functionally active nutrient system promoting neonatal growth of mammals. Cell growth is regulated by the nutrient-sensitive kinase mechanistic target of rapamycin complex 1 (mTORC1). There is still a lack of information on the mechanisms of mTORC1 up-regulation by milk consumption. This review presents milk as a materno-neonatal relay system functioning by transfer of preferential amino acids, which increase plasma levels of glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), insulin, growth hormone (GH) and insulin-like growth factor-1 (IGF-1) for mTORC1 activation. Importantly, milk exosomes, which regularly contain microRNA-21, most likely represent a genetic transfection system enhancing mTORC1-driven metabolic processes. Whereas human breast milk is the ideal food for infants allowing appropriate postnatal growth and species-specific metabolic programming, persistent high milk signaling during adolescence and adulthood by continued cow´s milk consumption may promote mTORC1-driven diseases of civilization. PMID:23883112

The role of subgrain boundaries in partial melting

NASA Astrophysics Data System (ADS)

Levine, Jamie S. F.; Mosher, Sharon; Rahl, Jeffrey M.

2016-08-01

Evidence for partial melting along subgrain boundaries in quartz and plagioclase is documented for rocks from the Lost Creek Gneiss of the Llano Uplift, central Texas, the Wet Mountains of central Colorado, and the Albany-Fraser Orogen, southwestern Australia. Domains of quartz or plagioclase crystals along subgrain boundaries are preferentially involved in partial melting over unstrained domains of these minerals. Material along subgrain boundaries in quartz and plagioclase has the same morphology as melt pseudomorphs present along grain boundaries and is commonly laterally continuous with this former grain boundary melt, indicating the material along subgrain boundaries can also be categorized as a melt pseudomorph. Subgrain boundaries consist of arrays of dislocations within a crystal lattice, and unlike fractures would not act as conduits for melt migration. Instead, the presence of former melt along subgrain boundaries requires that partial melting occurred in these locations because it is kinetically more favorable for melting reactions to occur there. Preferential melting in high strain locations may be attributed to strain energy, which provides a minor energetic contribution to the reaction and leads to preferential melting in locations with weakened bonds, and/or the presence of small quantities of water associated with dislocations, which may enhance diffusion rates or locally lower the temperature needed for partial melting.

The effect of trees on preferential flow and soil infiltrability in an agroforestry parkland in semiarid Burkina Faso.

PubMed

Bargués Tobella, A; Reese, H; Almaw, A; Bayala, J; Malmer, A; Laudon, H; Ilstedt, U

2014-04-01

Water scarcity constrains the livelihoods of millions of people in tropical drylands. Tree planting in these environments is generally discouraged due to the large water consumption by trees, but this view may neglect their potential positive impacts on water availability. The effect of trees on soil hydraulic properties linked to groundwater recharge is poorly understood. In this study, we performed 18 rainfall simulations and tracer experiments in an agroforestry parkland in Burkina Faso to investigate the effect of trees and associated termite mounds on soil infiltrability and preferential flow. The sampling points were distributed in transects each consisting of three positions: (i) under a single tree, (ii) in the middle of an open area, and (iii) under a tree associated with a termite mound. The degree of preferential flow was quantified through parameters based on the dye infiltration patterns, which were analyzed using image analysis of photographs. Our results show that the degree of preferential flow was highest under trees associated with termite mounds, intermediate under single trees, and minimal in the open areas. Tree density also had an influence on the degree of preferential flow, with small open areas having more preferential flow than large ones. Soil infiltrability was higher under single trees than in the open areas or under trees associated with a termite mound. The findings from this study demonstrate that trees have a positive impact on soil hydraulic properties influencing groundwater recharge, and thus such effects must be considered when evaluating the impact of trees on water resources in drylands. Trees in dryland landscapes increase soil infiltrability and preferential flow Termite mounds in association with trees further enhance preferential flow.

The effect of trees on preferential flow and soil infiltrability in an agroforestry parkland in semiarid Burkina Faso

PubMed Central

Bargués Tobella, A; Reese, H; Almaw, A; Bayala, J; Malmer, A; Laudon, H; Ilstedt, U

2014-01-01

Water scarcity constrains the livelihoods of millions of people in tropical drylands. Tree planting in these environments is generally discouraged due to the large water consumption by trees, but this view may neglect their potential positive impacts on water availability. The effect of trees on soil hydraulic properties linked to groundwater recharge is poorly understood. In this study, we performed 18 rainfall simulations and tracer experiments in an agroforestry parkland in Burkina Faso to investigate the effect of trees and associated termite mounds on soil infiltrability and preferential flow. The sampling points were distributed in transects each consisting of three positions: (i) under a single tree, (ii) in the middle of an open area, and (iii) under a tree associated with a termite mound. The degree of preferential flow was quantified through parameters based on the dye infiltration patterns, which were analyzed using image analysis of photographs. Our results show that the degree of preferential flow was highest under trees associated with termite mounds, intermediate under single trees, and minimal in the open areas. Tree density also had an influence on the degree of preferential flow, with small open areas having more preferential flow than large ones. Soil infiltrability was higher under single trees than in the open areas or under trees associated with a termite mound. The findings from this study demonstrate that trees have a positive impact on soil hydraulic properties influencing groundwater recharge, and thus such effects must be considered when evaluating the impact of trees on water resources in drylands. Key Points Trees in dryland landscapes increase soil infiltrability and preferential flow Termite mounds in association with trees further enhance preferential flow PMID:25641996

Group B Streptococcus Infections Caused by Improper Sourcing and Handling of Fish for Raw Consumption, Singapore, 2015-2016.

PubMed

Chau, Man L; Chen, Swaine L; Yap, Min; Hartantyo, Sri H P; Chiew, Paul K T; Fernandez, Charlene J; Wong, Wai K; Fong, Rockey K; Tan, Wei L; Tan, Brian Z Y; Ng, Youming; Aung, Kyaw T; Mehershahi, Kurosh S; Goh, Christopher; Kang, Joanne S L; Barkham, Timothy; Leong, Adeline O K; Gutiérrez, Ramona A; Ng, Lee C

2017-12-01

We assessed microbial safety and quality of raw fish sold in Singapore during 2015-2016 to complement epidemiologic findings for an outbreak of infection with group B Streptococcus serotype III sequence type (ST) 283 associated with raw fish consumption. Fish-associated group B Streptococcus ST283 strains included strains nearly identical (0-2 single-nucleotide polymorphisms) with the human outbreak strain, as well as strains in another distinct ST283 clade (57-71 single-nucleotide polymorphisms). Our investigations highlight the risk for contamination of freshwater fish (which are handled and distributed separately from saltwater fish sold as sashimi) and the need for improved hygienic handling of all fish for raw consumption. These results have led to updated policy and guidelines regarding the sale of ready-to-eat raw fish dishes in Singapore.

Beta-lactamase targeted enzyme activatable photosensitizers for antimicrobial PDT

NASA Astrophysics Data System (ADS)

Zheng, Xiang; Verma, Sarika; Sallum, Ulysses W.; Hasan, Tayyaba

2009-06-01

Photodynamic therapy (PDT) as a treatment modality for infectious disease has shown promise. However, most of the antimicrobial photosensitizers (PS) non-preferentially accumulate in both bacteria and host tissues, causing host tissue phototoxicity during treatment. We have developed a new antimicrobial PDT strategy which exploits beta-lactam resistance mechanism, one of the major drug-resistance bacteria evolved, to achieve enhanced target specificity with limited host damage. Our strategy comprises a prodrug construct with a PS and a quencher linked by beta-lactam ring, resulting in a diminished phototoxicity. This construct, beta-lactamase enzyme-activated-photosensitizer (beta-LEAP), can only be activated in the presence of both light and bacteria, and remains inactive elsewhere such as mammalian tissue. Beta-LEAP construct had shown specific cleavage by purified beta-lactamase and by beta-lactamase over-expressing methicillin resistant Staphylococcus aureus (MRSA). Specific photodynamic toxicity was observed towards MRSA, while dark and light toxicity were equivalent to reference strains. The prodrug design, synthesis and photophysical properties will be discussed.

Production and consumption of nitric oxide by three methanotrophic bacteria.

PubMed

Ren, T; Roy, R; Knowles, R

2000-09-01

We studied nitrogen oxide production and consumption by methanotrophs Methylobacter luteus (group I), Methylosinus trichosporium OB3b (group II), and an isolate from a hardwood swamp soil, here identified by 16S ribosomal DNA sequencing as Methylobacter sp. strain T20 (group I). All could consume nitric oxide (nitrogen monoxide, NO), and produce small amounts of nitrous oxide (N(2)O). Only Methylobacter strain T20 produced large amounts of NO (>250 parts per million by volume [ppmv] in the headspace) at specific activities of up to 2.0 x 10(-17) mol of NO cell(-1) day(-1), mostly after a culture became O(2) limited. Production of NO by strain T20 occurred mostly in nitrate-containing medium under anaerobic or nearly anaerobic conditions, was inhibited by chlorate, tungstate, and O(2), and required CH(4). Denitrification (methanol-supported N(2)O production from nitrate in the presence of acetylene) could not be detected and thus did not appear to be involved in the production of NO. Furthermore, cd(1) and Cu nitrite reductases, NO reductase, and N(2)O reductase could not be detected by PCR amplification of the nirS, nirK, norB, and nosZ genes, respectively. M. luteus and M. trichosporium produced some NO in ammonium-containing medium under aerobic conditions, likely as a result of methanotrophic nitrification and chemical decomposition of nitrite. For Methylobacter strain T20, arginine did not stimulate NO production under aerobiosis, suggesting that NO synthase was not involved. We conclude that strain T20 causes assimilatory reduction of nitrate to nitrite, which then decomposes chemically to NO. The production of NO by methanotrophs such as Methylobacter strain T20 could be of ecological significance in habitats near aerobic-anaerobic interfaces where fluctuating O(2) and nitrate availability occur.

Inbred mouse strains C57BL/6J and DBA/2J vary in sensitivity to a subset of bitter stimuli

PubMed Central

Boughter, John D; Raghow, Sandeep; Nelson, Theodore M; Munger, Steven D

2005-01-01

Background Common inbred mouse strains are genotypically diverse, but it is still poorly understood how this diversity relates to specific differences in behavior. To identify quantitative trait genes that influence taste behavior differences, it is critical to utilize assays that exclusively measure the contribution of orosensory cues. With a few exceptions, previous characterizations of behavioral taste sensitivity in inbred mouse strains have generally measured consumption, which can be confounded by post-ingestive effects. Here, we used a taste-salient brief-access procedure to measure taste sensitivity to eight stimuli characterized as bitter or aversive in C57BL/6J (B6) and DBA/2J (D2) mice. Results B6 mice were more sensitive than D2 mice to a subset of bitter stimuli, including quinine hydrochloride (QHCl), 6-n-propylthiouracil (PROP), and MgCl2. D2 mice were more sensitive than B6 mice to the bitter stimulus raffinose undecaacetate (RUA). These strains did not differ in sensitivity to cycloheximide (CYX), denatonium benzoate (DB), KCl or HCl. Conclusion B6-D2 taste sensitivity differences indicate that differences in consumption of QHCl, PROP, MgCl2 and RUA are based on immediate orosensory cues, not post-ingestive effects. The absence of a strain difference for CYX suggests that polymorphisms in a T2R-type taste receptor shown to be differentially sensitive to CYX in vitro are unlikely to differentially contribute to the CYX behavioral response in vivo. The results of these studies point to the utility of these common mouse strains and their associated resources for investigation into the genetic mechanisms of taste. PMID:15967025

Effects of antibiotic treatment on the lactobacillus composition of vaginal microbiota.

PubMed

Melkumyan, A R; Priputnevich, T V; Ankirskaya, A S; Murav'eva, V V; Lubasovskaya, L A

2015-04-01

We analyzed sensitivity of 123 vaginal lactobacillus strains to antibacterial substances. All lactobacillus strains were sensitive to ampicillin, cefazolin, cefotaxime, and vancomycin, and insensitive to metronidazole, trimethoprim/sulfamethoxazole, and levofloxacin. Lactobacillus strains demonstrated different sensitivity to gentamycin, clindamycin, erythromycin, ciprofloxacin, and tetracycline. The phenomenon of preferential selective influence of antibacterial drugs on the composition of lactobacilli of the vaginal microbiota, in which some lactobacilli survive as part of the vaginal microbiota and have a selective advantage over other types of lactobacilli, should be taken into account during treatment of vaginal infections and dysbiosis.

Serum resistance, gallium nitrate tolerance and extrapulmonary dissemination are linked to heme consumption in a bacteremic strain of Acinetobacter baumannii.

PubMed

de Léséleuc, Louis; Harris, Greg; KuoLee, Rhonda; Xu, H Howard; Chen, Wangxue

2014-05-01

Bacteremia caused by Acinetobacter baumannii is a highly lethal complication of hospital-acquired pneumonia. In the present study, we investigated the serum resistance, gallium nitrate tolerance and heme consumption of A. baumannii strain LAC-4 which was recently reported to display high virulence in a mouse pneumonia model with extrapulmonary dissemination leading to fatal bacteremia. This strain showed enhanced growth in mouse and fetal bovine serum that was independent of complement and was not observed with regular growth media. The LAC-4 strain was found to possess a high tolerance to gallium nitrate (GaN), whereas serum synergized with GaN in inhibiting A. baumannii strain ATCC 17978. We found that LAC-4 contains a heme oxygenase gene and expresses a highly efficient heme consumption system. This system can be fully blocked in vitro and in vivo by gallium protoporphyrin IX (GaPPIX). Inhibition of heme consumption by GaPPIX completely abrogated the growth advantage of LAC-4 in serum as well as its tolerance to GaN. More importantly, GaPPIX treatment of mice intranasally infected with LAC-4 prevented extrapulmonary dissemination and death. Thus, we propose that heme provides an additional source of iron for LAC-4 to bypass iron restriction caused by serum transferrin, lactoferrin or free gallium salts. Heme consumption systems in A. baumannii may constitute major virulence factors for lethal bacteremic isolates. Copyright © 2014 Crown Copyright and Elsevier Inc. Published by Elsevier GmbH.. All rights reserved.

Paternal and maternal alcohol consumption: effects on offspring in two strains of rats.

PubMed

Abel, E L

1989-08-01

Long-Evans and Sprague-Dawley male rats were given liquid alcohol diets containing 35%, 17.5%, or 0% ethanol-derived calories (EDC). The latter two groups were pair fed to the higher alcohol diet group. A fourth group received lab chow and water ad libitum to assess the role of paternal undernutrition associated with alcohol consumption. After three or four weeks of diet consumption, these males were bred to females of the same strain. Pregnant females were divided into similarly treated alcohol groups and were fed these diets beginning on gestation Day 8, thus creating a factorial study with strain, paternal, and maternal alcohol consumption as main factors. Paternal alcohol consumption was associated with decreased litter size, decreased testosterone levels, and a strain-related effect on offspring activity. Offspring activity decreased for those sired by 35% and 17.5% EDC Long-Evans fathers. Activity also decreased for offspring sired by 17.5% EDC Sprague-Dawley fathers but increased for those sired by 35% EDC fathers. Paternal alcohol consumption did not affect postnatal mortality or passive avoidance learning of offspring. Maternal alcohol consumption was associated with lower birth weights, lower offspring weights at weaning, increased postnatal mortality, and poorer passive avoidance learning. However, offspring activity was not affected. In a separate study, levels of alcohol in the testes were found to be somewhat, but not significantly, lower than blood alcohol levels. DNA taken from sperm of Long-Evans males consuming alcohol, migrated farther under pulsed field electrophoresis than DNA from control fathers, suggestive of an alcohol-related effect on sperm DNA.

Group B Streptococcus Infections Caused by Improper Sourcing and Handling of Fish for Raw Consumption, Singapore, 2015–2016

PubMed Central

Chau, Man L.; Chen, Swaine L.; Yap, Min; Hartantyo, Sri H.P.; Chiew, Paul K.T.; Fernandez, Charlene J.; Wong, Wai K.; Fong, Rockey K.; Tan, Wei L.; Tan, Brian Z.Y.; Ng, Youming; Aung, Kyaw T.; Mehershahi, Kurosh S.; Goh, Christopher; Kang, Joanne S.L.; Barkham, Timothy; Leong, Adeline O.K.; Gutiérrez, Ramona A.

2017-01-01

We assessed microbial safety and quality of raw fish sold in Singapore during 2015–2016 to complement epidemiologic findings for an outbreak of infection with group B Streptococcus serotype III sequence type (ST) 283 associated with raw fish consumption. Fish-associated group B Streptococcus ST283 strains included strains nearly identical (0–2 single-nucleotide polymorphisms) with the human outbreak strain, as well as strains in another distinct ST283 clade (57–71 single-nucleotide polymorphisms). Our investigations highlight the risk for contamination of freshwater fish (which are handled and distributed separately from saltwater fish sold as sashimi) and the need for improved hygienic handling of all fish for raw consumption. These results have led to updated policy and guidelines regarding the sale of ready-to-eat raw fish dishes in Singapore. PMID:29148967

Escherichia coli K1-Specific Bacteriophage CUS-3 Distribution and Function in Phase-Variable Capsular Polysialic Acid O Acetylation▿ †

PubMed Central

King, Michael R.; Vimr, Ross P.; Steenbergen, Susan M.; Spanjaard, Lodewijk; Plunkett, Guy; Blattner, Frederick R.; Vimr, Eric R.

2007-01-01

Escherichia coli K1 is the leading cause of human neonatal sepsis and meningitis and is important in other clinical syndromes of both humans and domestic animals; in this strain the polysialic acid capsule (K1 antigen) functions by inhibiting innate immunity. Recent discovery of the phase-variable capsular O acetylation mechanism indicated that the O-acetyltransferase gene, neuO, is carried on a putative K1-specific prophage designated CUS-3 (E. L. Deszo, S. M. Steenbergen, D. I. Freedberg, and E. R. Vimr, Proc. Natl. Acad. Sci. USA 102:5564-5569, 2005). Here we describe the isolation and characterization of a CUS-3 derivative (CUS-3a), demonstrating its morphology, lysogenization of a sensitive host, and the distribution of CUS-3 among a collection of 111 different K1 strains. The 40,207-bp CUS-3 genome was annotated from the strain RS218 genomic DNA sequence, indicating that most of the 63 phage open reading frames have their closest homologues in one of seven different lambdoid phages. Translational fusion of a reporter lacZ fragment to the hypervariable poly-Ψ domain facilitated measurement of phase variation frequencies, indicating no significant differences between switch rates or effects on rates of the methyl-directed mismatch repair system. PCR analysis of poly-Ψ domain length indicated preferential loss or gain of single 5′-AAGACTC-3′ nucleotide repeats. Analysis of a K1 strain previously reported as “locked on” indicated a poly-Ψ region with the least number of heptad repeats compatible with in-frame neuO expression. The combined results establish CUS-3 as an active mobile contingency locus in E. coli K1, indicating its capacity to mediate population-wide capsule variation. PMID:17601779

Escherichia coli K1-specific bacteriophage CUS-3 distribution and function in phase-variable capsular polysialic acid O acetylation.

PubMed

King, Michael R; Vimr, Ross P; Steenbergen, Susan M; Spanjaard, Lodewijk; Plunkett, Guy; Blattner, Frederick R; Vimr, Eric R

2007-09-01

Escherichia coli K1 is the leading cause of human neonatal sepsis and meningitis and is important in other clinical syndromes of both humans and domestic animals; in this strain the polysialic acid capsule (K1 antigen) functions by inhibiting innate immunity. Recent discovery of the phase-variable capsular O acetylation mechanism indicated that the O-acetyltransferase gene, neuO, is carried on a putative K1-specific prophage designated CUS-3 (E. L. Deszo, S. M. Steenbergen, D. I. Freedberg, and E. R. Vimr, Proc. Natl. Acad. Sci. USA 102:5564-5569, 2005). Here we describe the isolation and characterization of a CUS-3 derivative (CUS-3a), demonstrating its morphology, lysogenization of a sensitive host, and the distribution of CUS-3 among a collection of 111 different K1 strains. The 40,207-bp CUS-3 genome was annotated from the strain RS218 genomic DNA sequence, indicating that most of the 63 phage open reading frames have their closest homologues in one of seven different lambdoid phages. Translational fusion of a reporter lacZ fragment to the hypervariable poly-Psi domain facilitated measurement of phase variation frequencies, indicating no significant differences between switch rates or effects on rates of the methyl-directed mismatch repair system. PCR analysis of poly-Psi domain length indicated preferential loss or gain of single 5'-AAGACTC-3' nucleotide repeats. Analysis of a K1 strain previously reported as "locked on" indicated a poly-Psi region with the least number of heptad repeats compatible with in-frame neuO expression. The combined results establish CUS-3 as an active mobile contingency locus in E. coli K1, indicating its capacity to mediate population-wide capsule variation.

Variation in Nicotine Consumption in Inbred Mice Is Not Linked to Orosensory Ability

PubMed Central

Glatt, A. Rebecca; Denton, Kelley

2009-01-01

Genetic studies of nicotine addiction in mice have utilized the oral self-administration model. However, it is unclear if strain differences in nicotine consumption are influenced by variation in bitter taste sensitivity. We measured both nicotine consumption and nicotine brief-access licking behavior in several commonly used inbred strains of mice that were previously shown to differ in nicotine consumption. A/J (A), C57BL/6J (B6), and DBA/2J (D2) mice were given a 2-bottle choice test with a single concentration of nicotine (75 μg/ml; nicotine vs. water). Mice of these strains were also tested with a range of nicotine concentrations (5–400 μg/ml) using a brief-access test, which measures orosensory response and minimizes postingestive effects. Although B6 mice consumed more 75-μg/ml nicotine than A or D2 mice in the 2-bottle test, these strains did not differ in level of aversion to nicotine when tested with the brief-access procedure. Strain differences in orosensory response to nicotine were not found; yet, differences emerged during the 2-bottle tests. This study provides evidence that variation in intake level of nicotine is likely not due to differences in taste or trigeminal sensitivity but likely due to postingestive factors. PMID:18775876

Cachaça yeast strains: alternative starters to produce beer and bioethanol.

PubMed

Araújo, Thalita Macedo; Souza, Magalhães Teixeira; Diniz, Raphael Hermano Santos; Yamakawa, Celina Kiyomi; Soares, Lauren Bergmann; Lenczak, Jaciane Lutz; de Castro Oliveira, Juliana Velasco; Goldman, Gustavo Henrique; Barbosa, Edilene Alves; Campos, Anna Clara Silva; Castro, Ieso Miranda; Brandão, Rogelio Lopes

2018-04-16

This work was performed to verify the potential of yeast strains isolated from cachaça distilleries for two specific biotechnological applications: beer and bioethanol production. In the beer production, the strains were tested for characteristics required in brewery practices, such as: capacity to ferment maltose and maltotriose, ability to grow at lowest temperatures, low H 2 S production, and flocculation profile. Among the strains tested, two of them showed appropriate characteristics to produce two different beer styles: lager and ale. Moreover, both strains were tested for cachaça production and the results confirmed the capacity of these strains to improve the quality of cachaça. In the bioethanol production, the fermentation process was performed similarly to that used by bioethanol industries: recycling of yeast biomass in the fermentative process with sulfuric acid washings (pH 2.0). The production of ethanol, glycerol, organic acids, dry cell weight, carbohydrate consumption, and cellular viability were analyzed. One strain presented fermentative parameters similar to PE2, industrial/commercial strain, with equivalent ethanol yields and cellular viability during all fermentative cycles. This work demonstrates that cachaça distilleries seem to be an interesting environment to select new yeast strains to be used in biotechnology applications as beer and bioethanol production.

Effect of welding on creep damage evolution in P91B steel

NASA Astrophysics Data System (ADS)

Baral, J.; Swaminathan, J.; Chakrabarti, D.; Ghosh, R. N.

2017-07-01

Study of creep behavior of base metal (without weld) and welded specimens of P91B steel over a range of temperatures (600-650 °C) and stresses (50-180 MPa) showed similar values of minimum creep-rates for both specimens at higher stress regime (>100 MPa) whilst, significantly higher creep rates in the case of welded specimens at lower stress regime. Considering that welded specimen is comprised of two distinct structural regimes, i.e. weld affected zone and base metal, a method has been proposed for estimating the material parameters describing creep behavior of those regimes. Stress-strain distribution across welded specimen predicted from finite element analysis based on material parameters revealed preferential accumulation of stress and creep strain at the interface between weld zone and base metal. This is in-line with the experimental finding that creep rupture preferentially occurs at inter-critical heat affected zone in welded specimens owing to ferrite-martensite structure with coarse Cr23C6 particles.

Degradation of paracetamol by Pseudomonas aeruginosa strain HJ1012.

PubMed

Hu, Jun; Zhang, Li L; Chen, Jian M; Liu, Yu

2013-01-01

Pseudomonas aeruginosa strain HJ1012 was isolated on paracetamol as a sole carbon and energy source. This organism could completely degrade paracetamol as high as 2200 mg/L. Following paracetamol consumption, a CO₂ yield rate up to 71.4% proved that the loss of paracetamol was mainly via mineralization. Haldane's equation adequately described the relationship between the specific growth rate and substrate concentration. The maximum specific growth rate and yield coefficient were 0.201 g-Paracetamol/g-VSS·h and 0.101 mg of biomass yield/mg of paracetamol consumed, respectively. A total of 8 metabolic intermediates was identified and classified into aromatic compounds, carboxylic acids, and inorganic species (nitrite and nitrate ions). P-aminophenol and hydroquinone are the two key metabolites of the initial steps in the paracetamol catabolic pathway. Paracetamol is degraded predominantly via p-aminophenol to hydroquinone with subsequent ring fission, suggesting partially new pathways for paracetamol-degrading bacteria.

Salmonella-host cell interactions, changes in host cell architecture, and destruction of prostate tumor cells with genetically altered Salmonella.

PubMed

Zhong, Zhisheng; Kazmierczak, Robert A; Dino, Alison; Khreis, Rula; Eisenstark, Abraham; Schatten, Heide

2007-10-01

Increasingly, genetically modified Salmonella are being explored as a novel treatment for cancer because Salmonella preferentially replicate within tumors and destroy cancer cells without causing the septic shock that is typically associated with wild-type S. typhimurium infections. However, the mechanisms by which genetically modified Salmonella strains preferentially invade cancer cells have not yet been addressed in cellular detail. Here we present data that show S. typhimurium strains VNP20009, LT2, and CRC1674 invasion of PC-3M prostate cancer cells. S. typhimurium-infected PC-3M human prostate cancer cells were analyzed with immunofluorescence microscopy and transmission electron microscopy (TEM) at various times after inoculation. We analyzed microfilaments, microtubules, and DNA with fluorescence and immunofluorescence microscopy. 3T3 Phi-Yellow-mitochondria mouse 3T3 cells were used to study the effects of Salmonella infestation on mitochondria distribution in live cells. Our TEM results show gradual destruction of mitochondria within the PC-3M prostate cancer cells with complete loss of cristae at 8 h after inoculation. The fluorescence intensity in YFP-mitochondria-transfected mouse 3T3 cells decreased, which indicates loss of mitochondria structure. Interestingly, the nucleus does not appear affected by Salmonella within 8 h. Our data demonstrate that genetically modified S. typhimurium destroy PC-3M prostate cancer cells, perhaps by preferential destruction of mitochondria.

Biocatalytic desulfurization of thiophenic compounds and crude oil by newly isolated bacteria

PubMed Central

Mohamed, Magdy El-Said; Al-Yacoub, Zakariya H.; Vedakumar, John V.

2015-01-01

Microorganisms possess enormous highly specific metabolic activities, which enable them to utilize and transform nearly every known chemical class present in crude oil. In this context, one of the most studied biocatalytic processes is the biodesulfurization (BDS) of thiophenic sulfur-containing compounds such as benzothiophene (BT) and dibenzothiophene (DBT) in crude oils and refinery streams. Three newly isolated bacterial strains, which were affiliated as Rhodococcus sp. strain SA11, Stenotrophomonas sp. strain SA21, and Rhodococcus sp. strain SA31, were enriched from oil contaminated soil in the presence of DBT as the sole S source. GC-FID analysis of DBT-grown cultures showed consumption of DBT, transient formation of DBT sulfone (DBTO2) and accumulation of 2-hydroxybiphenyl (2-HBP). Molecular detection of the plasmid-borne dsz operon, which codes for the DBT desulfurization activity, revealed the presence of dszA, dszB, and dszC genes. These results point to the operation of the known 4S pathway in the BDS of DBT. The maximum consumption rate of DBT was 11 μmol/g dry cell weight (DCW)/h and the maximum formation rate of 2-HBP formation was 4 μmol/g DCW/h. Inhibition of both cell growth and DBT consumption by 2-HBP was observed for all isolates but SA11 isolate was the least affected. The isolated biocatalysts desulfurized other model DBT alkylated homologs. SA11 isolate was capable of desulfurizing BT as well. Resting cells of SA11 exhibited 10% reduction in total sulfur present in heavy crude oil and 18% reduction in total sulfur present in the hexane-soluble fraction of the heavy crude oil. The capabilities of the isolated bacteria to survive and desulfurize a wide range of S compounds present in crude oil are desirable traits for the development of a robust BDS biocatalyst to upgrade crude oils and refinery streams. PMID:25762990

Refinement of the probability density function model for preferential concentration of aerosol particles in isotropic turbulence

NASA Astrophysics Data System (ADS)

Zaichik, Leonid I.; Alipchenkov, Vladimir M.

2007-11-01

The purposes of the paper are threefold: (i) to refine the statistical model of preferential particle concentration in isotropic turbulence that was previously proposed by Zaichik and Alipchenkov [Phys. Fluids 15, 1776 (2003)], (ii) to investigate the effect of clustering of low-inertia particles using the refined model, and (iii) to advance a simple model for predicting the collision rate of aerosol particles. The model developed is based on a kinetic equation for the two-point probability density function of the relative velocity distribution of particle pairs. Improvements in predicting the preferential concentration of low-inertia particles are attained due to refining the description of the turbulent velocity field of the carrier fluid by including a difference between the time scales of the of strain and rotation rate correlations. The refined model results in a better agreement with direct numerical simulations for aerosol particles.

Chromosome specific repetitive DNA sequences

DOEpatents

Moyzis, Robert K.; Meyne, Julianne

1991-01-01

A method is provided for determining specific nucleotide sequences useful in forming a probe which can identify specific chromosomes, preferably through in situ hybridization within the cell itself. In one embodiment, chromosome preferential nucleotide sequences are first determined from a library of recombinant DNA clones having families of repetitive sequences. Library clones are identified with a low homology with a sequence of repetitive DNA families to which the first clones respectively belong and variant sequences are then identified by selecting clones having a pattern of hybridization with genomic DNA dissimilar to the hybridization pattern shown by the respective families. In another embodiment, variant sequences are selected from a sequence of a known repetitive DNA family. The selected variant sequence is classified as chromosome specific, chromosome preferential, or chromosome nonspecific. Sequences which are classified as chromosome preferential are further sequenced and regions are identified having a low homology with other regions of the chromosome preferential sequence or with known sequences of other family me This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

The Influence of Local DNA Sequence and DNA Repair Background on the Mutational Specificity of 1-Nitroso-8-Nitropyrene in Escherichia Coli: Inferences for Mutagenic Mechanisms

PubMed Central

Lambert, I. B.; Gordon, AJE.; Glickman, B. W.; McCalla, D. R.

1992-01-01

We have examined the mutational specificity of 1-nitroso-8-nitropyrene (1,8-NONP), an activated metabolite of the carcinogen 1,8-dinitropyrene, in the lacI gene of Escherichia coli strains which differ with respect to nucleotide excision repair (+/-ΔuvrB) and MucA/B-mediated error-prone translesion synthesis (+/-pKM101). Several different classes of mutation were recovered, of which frameshifts, base substitutions, and deletions were clearly induced by 1,8-NONP treatment. The high proportion of point mutations (>92%) which occurred at G·C sites correlates with the percentage of 1,8-NONP-DNA adducts which occur at the C(8) position of guanine. The most prominent frameshift mutations were -(G·C) events, which were induced by 1,8-NONP treatment in all strains, occurred preferentially in runs of guanine residues, and whose frequency increased markedly with the length of the reiterated sequence. Of the base substitution mutations G·C -> T·A transversions were induced to the greatest extent by 1,8-NONP. The distribution of the G·C -> T·A transversions was not influenced by the nature of flanking bases, nor was there a strand preference for these events. The presence of plasmid pKM101 specifically increased the frequency of G·C -> T·A transversions by a factor of 30-60. In contrast, the -(G·C) frameshift mutation frequency was increased only 2-4-fold in strains harboring pKM101 as compared to strains lacking this plasmid. There was, however, a marked influence of pKM101 on the strand specificity of frameshift mutation; a preference was observed for -G events on the transcribed strand. The ability of the bacteria to carry out nucleotide excision repair had a strong effect on the frequency of all classes of mutation but did not significantly influence either the overall distribution of mutational classes or the strand specificity of G·C -> T·A transversions and -(G·C) frameshifts. Deletion mutations were induced in the Δuvr, pKM101 strain. The endpoints of the majority of the deletion mutations were G·C rich and contained regions of considerable homology. The specificity of 1,8-NONP-induced mutation suggests that DNA containing 1,8-NONP adducts can be processed through different mutational pathways depending on the DNA sequence context of the adduct and the DNA repair background of the cell. PMID:1459443

Detection and genome characterization of bovine polyomaviruses in beef muscle and ground beef samples from Germany.

PubMed

Gräfe, Donina; Ehlers, Bernhard; Mäde, Dietrich; Ellerbroek, Lüppo; Seidler, Tassilo; Johne, Reimar

2017-01-16

Polyomaviruses are small, non-enveloped, circular double-stranded DNA viruses. Some polyomaviruses can induce tumors and cancer under certain circumstances. The bovine polyomaviruses (BPyV) 1-3 have been only scarcely analyzed so far. It was hypothesized that the consumption of beef meat containing polyomaviruses could contribute to the development of cancer in humans. In order to assess the distribution of the BPyV genome in meat from Germany, 101 beef muscle samples and 10 ground beef samples were analyzed here. A specific sample preparation method combined with or without rolling circle amplification (RCA), and BPyV-specific PCRs were developed and applied. BPyV-1 DNA was detected in 1/101 (1%) samples from beef meat and in 2/10 (20%) ground beef samples. BPyV-2 DNA was detected in 3/10 (30%) ground beef samples, whereas BPyV-3 was not detected in the samples. Application of RCA did not increase the detection rate in ground beef samples. Sequence analysis of the PCR products indicated the presence of BPyV-1, BPyV-2a and BPyV-2b. The whole genome of a BPyV-1 strain from ground beef meat showed 97.8% sequence identity to the BPyV-1 reference strain and that of a BPyV-2a strain from ground beef meet showed 99.9% sequence identity to strain 2aS11. It can be concluded that BPyV genomes can be frequently detected in ground beef samples, although higher sample numbers should be investigated in future to confirm this finding. Further studies should focus on the infectivity, tumorigenicity and heat resistance of the contained viruses in order to assess the risk of cancer induction through consumption of BPyVs present in beef products. Copyright © 2016 Elsevier B.V. All rights reserved.

Engineering Bacillus licheniformis as a thermophilic platform for the production of l-lactic acid from lignocellulose-derived sugars.

PubMed

Li, Chao; Gai, Zhongchao; Wang, Kai; Jin, Liping

2017-01-01

Bacillus licheniformis MW3 as a GRAS and thermophilic strain is a promising microorganism for chemical and biofuel production. However, its capacity to co-utilize glucose and xylose, the major sugars found in lignocellulosic biomass, is severely impaired by glucose-mediated carbon catabolite repression (CCR). In this study, a "dual-channel" process was implemented to engineer strain MW3 for simultaneous utilization of glucose and xylose, using l-lactic acid as a target product. A non-phosphotransferase system (PTS) glucose uptake route was activated via deletion of the glucose transporter gene ptsG and introduction of the galactose permease gene galP . After replacing the promoter of glucokinase gene glck with the strong promoter P als , the engineered strain recovered glucose consumption and utilized glucose and xylose simultaneously. Meanwhile, to improve the consumption rate of xylose in this strain, several measures were undertaken, such as relieving the regulation of the xylose repressor XylR, reducing the catabolite-responsive element, and optimizing the rate-limiting step. Knockout of ethanol and acetic acid pathway genes further increased lactic acid yield by 6.2%. The resultant strain, RH15, was capable of producing 121.9 g/L l-lactic acid at high yield (95.3%) after 40 h of fermentation from a mixture of glucose and xylose. When a lignocellulosic hydrolysate was used as the substrate, 99.3 g/L l-lactic acid was produced within 40 h, with a specific productivity of 2.48 g/[L h] and a yield of 94.6%. Our engineered strain B. licheniformis RH15 could thermophilically produced l-lactic acid from lignocellulosic hydrolysate with relatively high concentration and productivity at levels that were competitive with most reported cases of l-lactic acid-producers. Thus, the engineered strain might be used as a platform for the production of other chemicals. In addition to engineering the B. licheniformis strain, the "dual-channel" process might serve as an alternative method for engineering a variety of other strains.

PARABIOTIC INTOXICATION. II. THE DISTRIBUTION AND SURVIVAL OF Cr$sup 51$- LABELED RED BLOOD CELLS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokuda, S.; MacGillivray, M.H.

1962-04-01

The anemia and polycythemia in parent-to-F/sub 1/ parabiotic intoxication in mice were studied using Cr/sup 51/- and Fe/sup 59/ labeled red blood cells. It was observed that the anemia and polycythemia result from a shift in red cell mass from the hybrid into its parent strain partner. Because crosscirculation was observed between the parabionts during the anemia and polycythemia, the shift is attributed to unequal cross transfusion between the parabionts. There was neither preferential selection nor preferential destruction of either parental or hybrid red cells during the shift in red cell mass. (auth)

Lesions of the dopaminergic innervation of the nucleus accumbens medial shell delay the generation of preference for sucrose, but not of sexual pheromones.

PubMed

Martínez-Hernández, José; Lanuza, Enrique; Martínez-García, Fernando

2012-01-15

Male sexual pheromones are rewarding stimuli for female mice, able to induce conditioned place preference. To test whether processing these natural reinforcing stimuli depends on the dopaminergic innervation of the nucleus accumbens, as for other natural rewards, we compare the effects of specific lesions of the dopaminergic innervation of the medial shell of the nucleus accumbens on two different appetitive behaviours, 'pheromone seeking' and sucrose preferential intake. Female mice, with no previous experience with either adult male chemical stimuli or with sucrose, received injections of 6-hydroxydopamine (or vehicle) in the medial shell of the accumbens. Then, we analyzed their preference for male soiled-bedding and their preferential intake of a sucrose solution, with particular emphasis on the dynamics of acquisition of both natural rewards. The results indicate that both lesioned and sham animals showed similar preference for male sexual pheromones, which was constant along the test (linear dynamics). In contrast, lesioned animals differed from sham operated mice in the dynamics of sucrose consumption in their first test of sucrose preference. Sham animals showed an initial sucrose preference followed by preference for water, which can be interpreted as sucrose neophobia. Lesioned animals showed no preference at the beginning of the test, and a delayed sucrose preference appeared followed by a delayed neophobia. The next day, during a second sucrose-preference test, both groups displayed comparable and sustained preferential sucrose intake. Therefore, dopamine in the medial shell of the nucleus accumbens has a different role on the reward of sexual pheromones and sucrose. Copyright © 2011 Elsevier B.V. All rights reserved.

Mechanics of the human hamstring muscles during sprinting.

PubMed

Schache, Anthony G; Dorn, Tim W; Blanch, Peter D; Brown, Nicholas A T; Pandy, Marcus G

2012-04-01

An understanding of hamstring mechanics during sprinting is important for elucidating why these muscles are so vulnerable to acute strain-type injury. The purpose of this study was twofold: first, to quantify the biomechanical load (specifically, musculotendon strain, velocity, force, power, and work) experienced by the hamstrings across a full stride cycle; and second, to determine how these parameters differ for each hamstring muscle (i.e., semimembranosus (SM), semitendinosus (ST), biceps femoris long head (BF), biceps femoris short head (BF)). Full-body kinematics and ground reaction force data were recorded simultaneously from seven subjects while sprinting on an indoor running track. Experimental data were integrated with a three-dimensional musculoskeletal computer model comprised of 12 body segments and 92 musculotendon structures. The model was used in conjunction with an optimization algorithm to calculate musculotendon strain, velocity, force, power, and work for the hamstrings. SM, ST, and BF all reached peak strain, produced peak force, and formed much negative work (energy absorption) during terminal swing. The biomechanical load differed for each hamstring muscle: BF exhibited the largest peak strain, ST displayed the greatest lengthening velocity, and SM produced the highest peak force, absorbed and generated the most power, and performed the largest amount of positive and negative work. As peak musculotendon force and strain for BF, ST, and SM occurred around the same time during terminal swing, it is suggested that this period in the stride cycle may be when the biarticular hamstrings are at greatest injury risk. On this basis, hamstring injury prevention or rehabilitation programs should preferentially target strengthening exercises that involve eccentric contractions performed with high loads at longer musculotendon lengths.

Scale dependence of the alignment between strain rate and rotation in turbulent shear flow

NASA Astrophysics Data System (ADS)

Fiscaletti, D.; Elsinga, G. E.; Attili, A.; Bisetti, F.; Buxton, O. R. H.

2016-10-01

The scale dependence of the statistical alignment tendencies of the eigenvectors of the strain-rate tensor ei, with the vorticity vector ω , is examined in the self-preserving region of a planar turbulent mixing layer. Data from a direct numerical simulation are filtered at various length scales and the probability density functions of the magnitude of the alignment cosines between the two unit vectors | ei.ω ̂| are examined. It is observed that the alignment tendencies are insensitive to the concurrent large-scale velocity fluctuations, but are quantitatively affected by the nature of the concurrent large-scale velocity-gradient fluctuations. It is confirmed that the small-scale (local) vorticity vector is preferentially aligned in parallel with the large-scale (background) extensive strain-rate eigenvector e1, in contrast to the global tendency for ω to be aligned in parallel with the intermediate strain-rate eigenvector [Hamlington et al., Phys. Fluids 20, 111703 (2008), 10.1063/1.3021055]. When only data from regions of the flow that exhibit strong swirling are included, the so-called high-enstrophy worms, the alignment tendencies are exaggerated with respect to the global picture. These findings support the notion that the production of enstrophy, responsible for a net cascade of turbulent kinetic energy from large scales to small scales, is driven by vorticity stretching due to the preferential parallel alignment between ω and nonlocal e1 and that the strongly swirling worms are kinematically significant to this process.

Multistate Outbreak of Escherichia coli O157:H7 Infections Associated with Consumption of Fresh Spinach: United States, 2006.

PubMed

Sharapov, Umid M; Wendel, Arthur M; Davis, Jeffrey P; Keene, William E; Farrar, Jeffrey; Sodha, Samir; Hyytia-Trees, Eija; Leeper, Molly; Gerner-Smidt, Peter; Griffin, Patricia M; Braden, Chris

2016-12-01

During September to October, 2006, state and local health departments and the Centers for Disease Control and Prevention investigated a large, multistate outbreak of Escherichia coli O157:H7 infections. Case patients were interviewed regarding specific foods consumed and other possible exposures. E. coli O157:H7 strains isolated from human and food specimens were subtyped using pulsed-field gel electrophoresis and multiple-locus variable-number tandem repeat analyses (MLVA). Two hundred twenty-five cases (191 confirmed and 34 probable) were identified in 27 states; 116 (56%) case patients were hospitalized, 39 (19%) developed hemolytic uremic syndrome, and 5 (2%) died. Among 176 case patients from whom E. coli O157:H7 with the outbreak genotype (MLVA outbreak strain) was isolated and who provided details regarding spinach exposure, 161 (91%) reported fresh spinach consumption during the 10 days before illness began. Among 116 patients who provided spinach brand information, 106 (91%) consumed bagged brand A. E. coli O157:H7 strains were isolated from 13 bags of brand A spinach collected from patients' homes; isolates from 12 bags had the same MLVA pattern. Comprehensive epidemiologic and laboratory investigations associated this large multistate outbreak of E. coli O157:H7 infections with consumption of fresh bagged spinach. MLVA, as a supplement to pulsed-field gel electrophoresis genotyping of case patient isolates, was important to discern outbreak-related cases. This outbreak resulted in enhanced federal and industry guidance to improve the safety of leafy green vegetables and launched an independent collaborative approach to produce safety research in 2007.

The effect of trees on preferential flow and soil infiltrability in an agroforestry parkland in semiarid Burkina Faso

NASA Astrophysics Data System (ADS)

Bargués Tobella, A.; Reese, H.; Almaw, A.; Bayala, J.; Malmer, A.; Laudon, H.; Ilstedt, U.

2014-04-01

Water scarcity constrains the livelihoods of millions of people in tropical drylands. Tree planting in these environments is generally discouraged due to the large water consumption by trees, but this view may neglect their potential positive impacts on water availability. The effect of trees on soil hydraulic properties linked to groundwater recharge is poorly understood. In this study, we performed 18 rainfall simulations and tracer experiments in an agroforestry parkland in Burkina Faso to investigate the effect of trees and associated termite mounds on soil infiltrability and preferential flow. The sampling points were distributed in transects each consisting of three positions: (i) under a single tree, (ii) in the middle of an open area, and (iii) under a tree associated with a termite mound. The degree of preferential flow was quantified through parameters based on the dye infiltration patterns, which were analyzed using image analysis of photographs. Our results show that the degree of preferential flow was highest under trees associated with termite mounds, intermediate under single trees, and minimal in the open areas. Tree density also had an influence on the degree of preferential flow, with small open areas having more preferential flow than large ones. Soil infiltrability was higher under single trees than in the open areas or under trees associated with a termite mound. The findings from this study demonstrate that trees have a positive impact on soil hydraulic properties influencing groundwater recharge, and thus such effects must be considered when evaluating the impact of trees on water resources in drylands.

Slight Fermentation with Lactobacillus fermentium Improves the Taste (Sugar:Acid Ratio) of Citrus (Citrus reticulata cv. chachiensis) Juice.

PubMed

Yu, Yuanshan; Xiao, Gengsheng; Xu, Yujuan; Wu, Jijun; Fu, Manqin; Wen, Jing

2015-11-01

The aim of this study was to evaluate the hypothesis that fermentation with Lactobacillus fermentium, which can metabolize citric acid, could be applied in improving the taste (sugar:acid ratio) of citrus juice. During fermentation, the strain of L. fermentium can preferentially utilize citric acid of citrus (Citrus reticulata cv. Chachiensis) juice to support the growth without the consumption of sugar. After 6 h of fermentation with L. fermentium at 30 °C, the sugar:acid ratio of citrus juice increased to 22:1 from 12:1, which resulted in that the hedonic scores of sweetness, acidity and overall acceptability of fermented-pasteurized citrus juice were higher than the unfermented-pasteurized citrus juice. Compared with unfermented-pasteurized citrus juice, the ORAC value and total amino acid showed a reduction, and no significant change (P > 0.05) in the L*, a*, b*, total soluble phenolics and ascorbic acid (Vc) content in the fermented-pasteurized citrus juice was observed as compared with unfermented-pasteurized citrus juice. Hence, slight fermentation with L. fermentium can be used for improving the taste (sugar:acid ratio) of citrus juice with the well retaining of quality. © 2015 Institute of Food Technologists®

Salmonella as a biological "Trojan horse" for neoplasia: future possibilities including brain cancer.

PubMed

Mlynarczyk, Gregory S A; Berg, Carrie A; Withrock, Isabelle C; Fick, Meghan E; Anderson, Stephen J; Laboissonniere, Lauren A; Jefferson, Matthew A; Brewer, Matthew T; Stock, Matthew L; Lange, Jennifer K; Luna, K C; Acharya, Sreemoyee; Kanuri, Sriharsha; Sharma, Shaunik; Kondru, Naveen C; McCormack, Garrett R; Carlson, Steve A

2014-09-01

This manuscript considers available evidence that a specific Salmonella strain could be used as an effective orally-administered option for cancer therapy involving the brain. It has been established that Salmonella preferentially colonizes neoplastic tissue and thrives as a facultative anaerobe in the intra-tumor environment. Although Salmonella accumulates in tumors by passive processes, it is still possible for lipopolysaccharide to cause sepsis and endotoxic shock during the migration of bacteria to the tumor site. An LPS-free version of a recently identified Salmonella isolate may have the capability to circumvent the blood brain barrier and provide a safer method of reaching brain tumors. This isolate merits further research as a "Trojan horse" for future oral biotherapy of brain cancer. Copyright © 2014 Elsevier Ltd. All rights reserved.

Microbial Variants from Iron Ore Slimes: Mineral Specificity and pH Tolerance.

PubMed

Abhilash; Ghosh, A; Pandey, B D; Sarkar, S

2015-12-01

This paper describes the isolation of the native bacterial strains from the iron ore mines slime pond and its extremophilic characteristics. The two microbial isolates designated as CNIOS-1 and CNIOS-2 were grown in selective silicate broth at pH 7.0 and the organisms were tested for their selective adhesion on silicate and alumina minerals. The silicate bacteria with their exopolymers are very potent to grow over aluminosilicates. It was established that CNIOS-1 grew preferentially in the presence of silicate mineral compared to CNIOS-2 which grew in the presence of alumina. The organisms were tested for growth at various pH and trials were carried to define their efficacy for eventual applications to remove gangue minerals of silica and alumina from the raw material.

Cumulative Burden of Myocardial Dysfunction in Cardiac Amyloidosis Assessed Using Four-Chamber Cardiac Strain.

PubMed

Kado, Yuichiro; Obokata, Masaru; Nagata, Yasufumi; Ishizu, Tomoko; Addetia, Karima; Aonuma, Kazutaka; Kurabayashi, Masahiko; Lang, Roberto M; Takeuchi, Masaaki; Otsuji, Yutaka

2016-11-01

The aim of this study was to test the hypothesis that prognosis in patients with cardiac amyloidosis is closely coupled with amyloid burden in all four cardiac chambers. The goal was to evaluate longitudinal strain (LS) in each cardiac chamber and to determine whether LS in specific cardiac chambers is preferentially associated with prognosis over conventional two-dimensional echocardiographic parameters in patients with cardiac amyloidosis. Patients with two phenotypes of left ventricular (LV) hypertrophy (cardiac amyloidosis in 55 patients and nonobstructive hypertrophic cardiomyopathy in 40 patients) and 55 healthy subjects were retrospectively enrolled for the simultaneous assessment of LS of all four cardiac chambers in the apical four-chamber view. Patients with cardiac amyloidosis were followed up to record major adverse cardiovascular events, including cardiac death, heart transplantation, nonfatal myocardial infarction, ventricular tachyarrhythmia, and exacerbation of heart failure requiring hospitalization. LS in each chamber was significantly depressed in patients with both LV hypertrophy phenotypes compared with healthy subjects. Right atrial LS was significantly lower in patients with cardiac amyloidosis than those with nonobstructive hypertrophic cardiomyopathy after adjusting for LV ejection fraction and LV mass index. During a median follow-up period of 10 months, major adverse cardiovascular events developed in 22 patients with cardiac amyloidosis. Four-chamber LS were significantly associated with major adverse cardiovascular events, with incremental value over traditional echocardiographic parameters. Cardiac amyloidosis involves all cardiac chambers, and thus, chamber-specific strain analysis may be useful to assess the total cumulative burden of cardiac dysfunction. Copyright © 2016 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

[Identification of genes that are specifically/preferentially expressed in developing cotton fibers by mRNA fluorescence differential display (FDD)].

PubMed

Sun, Jie; Li, Yuan-Li; Wang, Ruo-Hai; Xia, Gui-Xian

2004-01-01

Fluorescence differential display (FDD) technique was used to identify genes that are specifically or preferentially expressed in different developmental stages of cotton fiber cells. One hundred and nine differentially displayed cDNA fragments were isolated using 9, 21 and 27 DPA (days postanthesis) fibers as experimental materials. By a combination of two rounds of reverse Northern hybridization and Northern blot analyses, a number of such cDNA fragments were proved to represent fiber-specific/preferential genes. Sequencing determination and database searching indicated that most of these genes are novel. This work is an important step towards cloning the full-length cDNAs and characterizing the cellular functions of aforementioned genes in fiber development.

Bifidobacteria exert strain-specific effects on stress-related behavior and physiology in BALB/c mice.

PubMed

Savignac, H M; Kiely, B; Dinan, T G; Cryan, J F

2014-11-01

Accumulating evidence suggests that commensal bacteria consumption has the potential to have a positive impact on stress-related psychiatric disorders. However, the specific bacteria influencing behaviors related to anxiety and depression remain unclear. To this end, we compared the effects of two different Bifidobacteria on anxiety and depression-like behavior; an antidepressant was also used as a comparator. Innately anxious BALB/c mice received daily Bifidobacterium longum (B.) 1714, B. breve 1205, the antidepressant escitalopram or vehicle treatment for 6 weeks. Behavior was assessed in stress-induced hyperthermia test, marble burying, elevated plus maze, open field, tail suspension test, and forced swim test. Physiological responses to acute stress were also assessed. Both Bifidobacteria and escitalopram reduced anxiety in the marble burying test; however, only B. longum 1714 decreased stress-induced hyperthermia. B. breve 1205 induced lower anxiety in the elevated plus maze whereas B. longum 1714 induced antidepressant-like behavior in the tail suspension test. However, there was no difference in corticosterone levels between groups. These data show that these two Bifidobacteria strains reduced anxiety in an anxious mouse strain. These results also suggest that each bacterial strain has intrinsic effects and may be beneficially specific for a given disorder. These findings strengthen the role of gut microbiota supplementation as psychobiotic-based strategies for stress-related brain-gut axis disorders, opening new avenues in the field of neurogastroenterology. © 2014 John Wiley & Sons Ltd.

Expression of a codon-optimized β-glucosidase from Cellulomonas flavigena PR-22 in Saccharomyces cerevisiae for bioethanol production from cellobiose.

PubMed

Ríos-Fránquez, Francisco Javier; González-Bautista, Enrique; Ponce-Noyola, Teresa; Ramos-Valdivia, Ana Carmela; Poggi-Varaldo, Héctor Mario; García-Mena, Jaime; Martinez, Alfredo

2017-05-01

Bioethanol is one of the main biofuels produced from the fermentation of saccharified agricultural waste; however, this technology needs to be optimized for profitability. Because the commonly used ethanologenic yeast strains are unable to assimilate cellobiose, several efforts have been made to express cellulose hydrolytic enzymes in these yeasts to produce ethanol from lignocellulose. The C. flavigenabglA gene encoding β-glucosidase catalytic subunit was optimized for preferential codon usage in S. cerevisiae. The optimized gene, cloned into the episomal vector pRGP-1, was expressed, which led to the secretion of an active β-glucosidase in transformants of the S. cerevisiae diploid strain 2-24D. The volumetric and specific extracellular enzymatic activities using pNPG as substrate were 155 IU L -1 and 222 IU g -1 , respectively, as detected in the supernatant of the cultures of the S. cerevisiae RP2-BGL transformant strain growing in cellobiose (20 g L -1 ) as the sole carbon source for 48 h. Ethanol production was 5 g L -1 after 96 h of culture, which represented a yield of 0.41 g g -1 of substrate consumed (12 g L -1 ), equivalent to 76% of the theoretical yield. The S. cerevisiae RP2-BGL strain expressed the β-glucosidase extracellularly and produced ethanol from cellobiose, which makes this microorganism suitable for application in ethanol production processes with saccharified lignocellulose.

Life cycle assessment of microalgae-based aviation fuel: Influence of lipid content with specific productivity and nitrogen nutrient effects.

PubMed

Guo, Fang; Zhao, Jing; A, Lusi; Yang, Xiaoyi

2016-12-01

The aim of this work is to compare the life cycle assessments of low-N and normal culture conditions for a balance between the lipid content and specific productivity. In order to achieve the potential contribution of lipid content to the life cycle assessment, this study established relationships between lipid content (nitrogen effect) and specific productivity based on three microalgae strains including Chlorella, Isochrysis and Nannochloropsis. For microalgae-based aviation fuel, the effects of the lipid content on fossil fuel consumption and greenhouse gas (GHG) emissions are similar. The fossil fuel consumption (0.32-0.68MJ·MJ -1 MBAF) and GHG emissions (17.23-51.04gCO 2 e·MJ -1 MBAF) increase (59.70-192.22%) with the increased lipid content. The total energy input decreases (2.13-3.08MJ·MJ -1 MBAF, 14.91-27.95%) with the increased lipid content. The LCA indicators increased (0-47.10%) with the decreased nitrogen recovery efficiency (75-50%). Copyright © 2016 Elsevier Ltd. All rights reserved.

Cell Viability and Functionality of Probiotic Bacteria in Dairy Products

PubMed Central

Vinderola, Gabriel; Binetti, Ana; Burns, Patricia; Reinheimer, Jorge

2011-01-01

Probiotic bacteria, according to the definition adopted by the World Health Organization in 2002, are live microorganisms, which when administered in adequate amounts confer a health benefit to the host. Recent studies show that the same probiotic strain produced and/or preserved under different storage conditions, may present different responses regarding their susceptibility to the adverse conditions of the gastrointestinal tract, its capacity to adhere to the intestinal epithelium, or its immunomodulating capacity, the functionality being affected without changes in cell viability. This could imply that the control of cell viability is not always enough to guarantee the functionality (probiotic capacity) of a strain. Therefore, a new challenge arises for food technologists and microbiologists when it comes to designing and monitoring probiotic food: to be able to monitor the functionality of a probiotic microorganism throughout all the stages the strain goes through from the moment it is produced and included in the food vehicle, until the moment of consumption. Conventional methodological tools or others still to be developed must be used. The application of cell membrane functionality markers, the use of tests of resistance to intestinal barriers, the study of surface properties and the application of in vivo models come together as complementary tools to assess the actual capacity of a probiotic organism in a specific food, to exert functional effects regardless of the number of viable cells present at the moment of consumption. PMID:21833320

Parametric studies of metabolic cooperativity in Escherichia coli colonies: Strain and geometric confinement effects

PubMed Central

Cole, John A.; Luthey-Schulten, Zaida

2017-01-01

Characterizing the complex spatial and temporal interactions among cells in a biological system (i.e. bacterial colony, microbiome, tissue, etc.) remains a challenge. Metabolic cooperativity in these systems can arise due to the subtle interplay between microenvironmental conditions and the cells’ regulatory machinery, often involving cascades of intra- and extracellular signalling molecules. In the simplest of cases, as demonstrated in a recent study of the model organism Escherichia coli, metabolic cross-feeding can arise in monoclonal colonies of bacteria driven merely by spatial heterogeneity in the availability of growth substrates; namely, acetate, glucose and oxygen. Another recent study demonstrated that even closely related E. coli strains evolved different glucose utilization and acetate production capabilities, hinting at the possibility of subtle differences in metabolic cooperativity and the resulting growth behavior of these organisms. Taking a first step towards understanding the complex spatio-temporal interactions within microbial populations, we performed a parametric study of E. coli growth on an agar substrate and probed the dependence of colony behavior on: 1) strain-specific metabolic characteristics, and 2) the geometry of the underlying substrate. To do so, we employed a recently developed multiscale technique named 3D dynamic flux balance analysis which couples reaction-diffusion simulations with iterative steady-state metabolic modeling. Key measures examined include colony growth rate and shape (height vs. width), metabolite production/consumption and concentration profiles, and the emergence of metabolic cooperativity and the fractions of cell phenotypes. Five closely related strains of E. coli, which exhibit large variation in glucose consumption and organic acid production potential, were studied. The onset of metabolic cooperativity was found to vary substantially between these five strains by up to 10 hours and the relative fraction of acetate utilizing cells within the colonies varied by a factor of two. Additionally, growth with six different geometries designed to mimic those that might be found in a laboratory, a microfluidic device, and inside a living organism were considered. Geometries were found to have complex, often nonlinear effects on colony growth and cross-feeding with “hard” features resulting in larger effect than “soft” features. These results demonstrate that strain-specific features and spatial constraints imposed by the growth substrate can have significant effects even for microbial populations as simple as isogenic E. coli colonies. PMID:28820904

Parametric studies of metabolic cooperativity in Escherichia coli colonies: Strain and geometric confinement effects.

PubMed

Peterson, Joseph R; Cole, John A; Luthey-Schulten, Zaida

2017-01-01

Characterizing the complex spatial and temporal interactions among cells in a biological system (i.e. bacterial colony, microbiome, tissue, etc.) remains a challenge. Metabolic cooperativity in these systems can arise due to the subtle interplay between microenvironmental conditions and the cells' regulatory machinery, often involving cascades of intra- and extracellular signalling molecules. In the simplest of cases, as demonstrated in a recent study of the model organism Escherichia coli, metabolic cross-feeding can arise in monoclonal colonies of bacteria driven merely by spatial heterogeneity in the availability of growth substrates; namely, acetate, glucose and oxygen. Another recent study demonstrated that even closely related E. coli strains evolved different glucose utilization and acetate production capabilities, hinting at the possibility of subtle differences in metabolic cooperativity and the resulting growth behavior of these organisms. Taking a first step towards understanding the complex spatio-temporal interactions within microbial populations, we performed a parametric study of E. coli growth on an agar substrate and probed the dependence of colony behavior on: 1) strain-specific metabolic characteristics, and 2) the geometry of the underlying substrate. To do so, we employed a recently developed multiscale technique named 3D dynamic flux balance analysis which couples reaction-diffusion simulations with iterative steady-state metabolic modeling. Key measures examined include colony growth rate and shape (height vs. width), metabolite production/consumption and concentration profiles, and the emergence of metabolic cooperativity and the fractions of cell phenotypes. Five closely related strains of E. coli, which exhibit large variation in glucose consumption and organic acid production potential, were studied. The onset of metabolic cooperativity was found to vary substantially between these five strains by up to 10 hours and the relative fraction of acetate utilizing cells within the colonies varied by a factor of two. Additionally, growth with six different geometries designed to mimic those that might be found in a laboratory, a microfluidic device, and inside a living organism were considered. Geometries were found to have complex, often nonlinear effects on colony growth and cross-feeding with "hard" features resulting in larger effect than "soft" features. These results demonstrate that strain-specific features and spatial constraints imposed by the growth substrate can have significant effects even for microbial populations as simple as isogenic E. coli colonies.

In-situ EBSD study of deformation behavior of retained austenite in a low-carbon quenching and partitioning steel via uniaxial tensile tests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Wan-song

Through using in-situ electron back-scattered diffraction and uniaxial tensile tests, this work mainly focuses on the deformation behavior of retained austenite (RA) in a low-carbon quenching and partitioning (Q&P) steel. In this paper, three different types of RA can be distinguished from different locations, respectively, RA grains at the triple edges, twinned austenite and RA grains positioned between martensite. The results have shown that grains at the triple edges and twinned austenite could transform easily with increasing strain, i.e. are less stable when compared with RA grains distributed between martensite that could resist a larger plastic deformation. Meanwhile, the strainmore » leads to rotations of RA grains distributed at the triple edges and between martensite. Moreover, RA grains with a similar orientation undergone similar rotations with the same true strain. These RA grains rotated along a specific slip plane and slip direction and the grain rotation is taken as a significant factor to improve the ductility of steel. In addition, grain sizes of RA decreased gradually with an increase of true strain and smaller (0–0.2 μm) grains were more capable of resisting the deformation. According to kernel average misorientation (KAM) analysis, it can be found that strain distribution is preferentially localized near martensite–austenite phase boundaries and in the interior of martensite. The average KAM values increased continuously with increasing true strain. - Highlights: •The in-situ and ex-situ tensile specimens differ to some extent in mechanical properties. •Retained austenite grains at the triple edges and twinned austenite transformed easily at the early stage of true strain. •Film-like retained austenite grains only rotated prior to the transformation during straining. •Retained austenite grains having with a similar orientation experienced similar rotations during the same true strain.« less

Preferential Use of CXCR4 by R5X4 Human Immunodeficiency Virus Type 1 Isolates for Infection of Primary Lymphocytes

PubMed Central

Yi, Yanjie; Shaheen, Farida; Collman, Ronald G.

2005-01-01

Coreceptor specificity of human immunodeficiency virus type 1 (HIV-1) strains is generally defined in vitro in cell lines expressing CCR5 or CXCR4, but lymphocytes and macrophages are the principal targets in vivo. CCR5-using (R5) variants dominate early in infection, but strains that use CXCR4 emerge later in a substantial minority of subjects. Many or most CXCR4-using variants can use both CXCR4 and CCR5 (R5X4), but the pathways that are actually used to cause infection in primary cells and in vivo are unknown. We examined several R5X4 prototype and primary isolates and found that they all were largely or completely restricted to CXCR4-mediated entry in primary lymphocytes, even though lymphocytes are permissive for CCR5-mediated entry by R5 strains. In contrast, in primary macrophages R5X4 isolates used both CCR5 and CXCR4. The R5X4 strains were also more sensitive than R5 strains to CCR5 blocking, suggesting that interactions between the R5X4 strains and CCR5 are less efficient. These results indicate that coreceptor phenotyping in transformed cells does not necessarily predict utilization in primary cells, that variability exists among HIV-1 isolates in the ability to use CCR5 expressed on lymphocytes, and that many or most strains characterized as R5X4 are functionally X4 in primary lymphocytes. Less efficient interactions between R5X4 strains and CCR5 may be responsible for the inability to use CCR5 on lymphocytes, which express relatively low CCR5 levels. Since isolates that acquire CXCR4 utilization retain the capacity to use CCR5 on macrophages despite their inability to use it on lymphocytes, these results also raise the possibility that a CCR5-mediated macrophage reservoir is required for sustained infection in vivo. PMID:15650174

Effect of long-term caloric restriction on oxygen consumption and body temperature in two different strains of mice

PubMed Central

Ferguson, Melissa; Sohal, Barbara H.; Forster, Michael J.; Sohal, Rajindar S.

2007-01-01

The hypothesis, that a decrease in metabolic rate mediates the life span prolonging effect of caloric restriction (CR), was tested using two strains of mice, one of which, C57BL/6, exhibits life span extension as a result of CR, while the other, DBA/2, shows little or no effect. Comparisons of the rate of resting oxygen consumption and body temperature were made between the strains after they were fed ad libitum (AL) or maintained under 40% CR, from 4 to 16 months of age. Ad libitum-fed mice of the two strains weighed the same when young and consumed similar amounts of food throughout the experiment; however, the C57BL/6 mice weighed 25% more than DBA/2 mice at 15 months of age. The rate of oxygen consumption was normalized as per gram body weight, lean body mass or organ weight as well as per animal. The body temperature and the rate of oxygen consumption, expressed according to all of the four criteria, were decreased in the DBA/2 mice following CR. The C57BL/6 mice also showed a CR-related decrease in body temperature and in the rate of oxygen consumption per animal and when normalized according to lean body mass or organ weight. The results of this study indicate that CR indeed lowers the rate of metabolism; however, this effect by CR does not necessarily entail the prolongation of the life span of mice. PMID:17822741

Effect of long-term caloric restriction on oxygen consumption and body temperature in two different strains of mice.

PubMed

Ferguson, Melissa; Sohal, Barbara H; Forster, Michael J; Sohal, Rajindar S

2007-10-01

The hypothesis, that a decrease in metabolic rate mediates the life span prolonging effect of caloric restriction (CR), was tested using two strains of mice, one of which, C57BL/6, exhibits life span extension as a result of CR, while the other, DBA/2, shows little or no effect. Comparisons of the rate of resting oxygen consumption and body temperature were made between the strains after they were fed ad libitum (AL) or maintained under 40% CR, from 4 to 16 months of age. Ad libitum-fed mice of the two strains weighed the same when young and consumed similar amounts of food throughout the experiment; however, the C57BL/6 mice weighed 25% more than DBA/2 mice at 15 months of age. The rate of oxygen consumption was normalized as per gram body weight, lean body mass or organ weight as well as per animal. The body temperature and the rate of oxygen consumption, expressed according to all of the four criteria, were decreased in the DBA/2 mice following CR. The C57BL/6 mice also showed a CR-related decrease in body temperature and in the rate of oxygen consumption per animal and when normalized according to lean body mass or organ weight. The results of this study indicate that CR indeed lowers the rate of metabolism; however, this effect by CR does not necessarily entail the prolongation of the life span of mice.

Production of High-Viscosity Whey Broths by a Lactose-Utilizing Xanthomonas campestris Strain.

PubMed

Schwartz, R D; Bodie, E A

1985-12-01

Xanthomonas campestris BB-1L was isolated by enrichment and selection by serial passage in a lactose-minimal medium. When BB-1L was subsequently grown in medium containing only 4% whey and 0.05% yeast extract, the lactose was consumed and broth viscosities greater than 500 cps at a 12 s shear rate were produced. Prolonged maintenance in whey resulted in the loss of the ability of BB-1L to produce viscous broths in whey, indicating a reversion to preferential growth on whey protein, like the parent strain.

Demonstration of specific binding of heparin to Plasmodium falciparum-infected vs. non-infected red blood cells by single-molecule force spectroscopy

NASA Astrophysics Data System (ADS)

Valle-Delgado, Juan José; Urbán, Patricia; Fernàndez-Busquets, Xavier

2013-04-01

Glycosaminoglycans (GAGs) play an important role in the sequestration of Plasmodium falciparum-infected red blood cells (pRBCs) in the microvascular endothelium of different tissues, as well as in the formation of small clusters (rosettes) between infected and non-infected red blood cells (RBCs). Both sequestration and rosetting have been recognized as characteristic events in severe malaria. Here we have used heparin and pRBCs infected by the 3D7 strain of P. falciparum as a model to study GAG-pRBC interactions. Fluorescence microscopy and fluorescence-assisted cell sorting assays have shown that exogenously added heparin has binding specificity for pRBCs (preferentially for those infected with late forms of the parasite) vs. RBCs. Heparin-pRBC adhesion has been probed by single-molecule force spectroscopy, obtaining an average binding force ranging between 28 and 46 pN depending on the loading rate. No significant binding of heparin to non-infected RBCs has been observed in control experiments. This work represents the first approach to quantitatively evaluate GAG-pRBC molecular interactions at the individual molecule level.Glycosaminoglycans (GAGs) play an important role in the sequestration of Plasmodium falciparum-infected red blood cells (pRBCs) in the microvascular endothelium of different tissues, as well as in the formation of small clusters (rosettes) between infected and non-infected red blood cells (RBCs). Both sequestration and rosetting have been recognized as characteristic events in severe malaria. Here we have used heparin and pRBCs infected by the 3D7 strain of P. falciparum as a model to study GAG-pRBC interactions. Fluorescence microscopy and fluorescence-assisted cell sorting assays have shown that exogenously added heparin has binding specificity for pRBCs (preferentially for those infected with late forms of the parasite) vs. RBCs. Heparin-pRBC adhesion has been probed by single-molecule force spectroscopy, obtaining an average binding force ranging between 28 and 46 pN depending on the loading rate. No significant binding of heparin to non-infected RBCs has been observed in control experiments. This work represents the first approach to quantitatively evaluate GAG-pRBC molecular interactions at the individual molecule level. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr32821f

Production and Consumption of Nitric Oxide by Three Methanotrophic Bacteria

PubMed Central

Ren, Tie; Roy, Réal; Knowles, Roger

2000-01-01

We studied nitrogen oxide production and consumption by methanotrophs Methylobacter luteus (group I), Methylosinus trichosporium OB3b (group II), and an isolate from a hardwood swamp soil, here identified by 16S ribosomal DNA sequencing as Methylobacter sp. strain T20 (group I). All could consume nitric oxide (nitrogen monoxide, NO), and produce small amounts of nitrous oxide (N2O). Only Methylobacter strain T20 produced large amounts of NO (>250 parts per million by volume [ppmv] in the headspace) at specific activities of up to 2.0 × 10−17 mol of NO cell−1 day−1, mostly after a culture became O2 limited. Production of NO by strain T20 occurred mostly in nitrate-containing medium under anaerobic or nearly anaerobic conditions, was inhibited by chlorate, tungstate, and O2, and required CH4. Denitrification (methanol-supported N2O production from nitrate in the presence of acetylene) could not be detected and thus did not appear to be involved in the production of NO. Furthermore, cd1 and Cu nitrite reductases, NO reductase, and N2O reductase could not be detected by PCR amplification of the nirS, nirK, norB, and nosZ genes, respectively. M. luteus and M. trichosporium produced some NO in ammonium-containing medium under aerobic conditions, likely as a result of methanotrophic nitrification and chemical decomposition of nitrite. For Methylobacter strain T20, arginine did not stimulate NO production under aerobiosis, suggesting that NO synthase was not involved. We conclude that strain T20 causes assimilatory reduction of nitrate to nitrite, which then decomposes chemically to NO. The production of NO by methanotrophs such as Methylobacter strain T20 could be of ecological significance in habitats near aerobic-anaerobic interfaces where fluctuating O2 and nitrate availability occur. PMID:10966405

High temperature tension-compression fatigue behavior of a tungsten copper composite

NASA Technical Reports Server (NTRS)

Verrilli, Michael J.; Gabb, Timothy P.

1990-01-01

The high temperature fatigue of a (O)12 tungsten fiber reinforced copper matrix composite was investigated. Specimens having fiber volume percentages of 10 and 36 were fatigued under fully-reversed, strain-controlled conditions at both 260 and 560 C. The fatigue life was found to be independent of fiber volume fraction because fatigue damage preferentially occurred in the matrix. Also, the composite fatigue lives were shorter at 560 C as compared to 260 C due to changes in mode of matrix failure. On a total strain basis, the fatigue life of the composite at 560 C was the same as the life of unreinforced copper, indicating that the presence of the fibers did not degrade the fatigue resistance of the copper matrix in this composite system. Comparison of strain-controlled fatigue data to previously-generated load-controlled data revealed that the strain-controlled fatigue lives were longer because of mean strain and mean stress effects.

Anisotropic Negative Thermal Expansion Behavior of the As-Fabricated Ti-Rich and Equiatomic Ti-Ni Alloys Induced by Preferential Grain Orientation

NASA Astrophysics Data System (ADS)

Zhao, Zhong-Xun; Ma, Xiao; Cao, Shan-Shan; Ke, Chang-Bo; Zhang, Xin-Ping

2017-12-01

The present study focuses on the anisotropic negative thermal expansion (NTE) behaviors of Ti-rich (Ti54Ni46) and equiatomic Ti-Ni (Ti50Ni50) alloys fabricated by vacuum arc melting and without subsequent plastic deformation. Both alloys exhibit NTE responses in vertical and horizontal directions, and the total strains and CTEs of the NTE stage along the two mutually perpendicular measuring directions are obviously different, indicating obvious anisotropic NTE behavior of the alloys. Besides, the numerical differences between the starting temperature of NTE and austenitic transformation and between the finishing temperature of NTE and austenitic transformation are very small, which indicates that an apparent relationship exists between the NTE behavior and the phase transformation. The microstructure in the vertical cross sections shows obviously preferential orientation characteristics: Ti2Ni phases of both alloys grow along the vertical direction, and B19' martensite of Ti50Ni50 alloy has distinct preferential orientation, which results from a large temperature gradient between the top and the bottom of the button ingots during solidification. The microstructure with preferential orientation induces the anisotropic NTE behavior of the samples.

Anisotropic Negative Thermal Expansion Behavior of the As-Fabricated Ti-Rich and Equiatomic Ti-Ni Alloys Induced by Preferential Grain Orientation

NASA Astrophysics Data System (ADS)

Zhao, Zhong-Xun; Ma, Xiao; Cao, Shan-Shan; Ke, Chang-Bo; Zhang, Xin-Ping

2018-03-01

The present study focuses on the anisotropic negative thermal expansion (NTE) behaviors of Ti-rich (Ti54Ni46) and equiatomic Ti-Ni (Ti50Ni50) alloys fabricated by vacuum arc melting and without subsequent plastic deformation. Both alloys exhibit NTE responses in vertical and horizontal directions, and the total strains and CTEs of the NTE stage along the two mutually perpendicular measuring directions are obviously different, indicating obvious anisotropic NTE behavior of the alloys. Besides, the numerical differences between the starting temperature of NTE and austenitic transformation and between the finishing temperature of NTE and austenitic transformation are very small, which indicates that an apparent relationship exists between the NTE behavior and the phase transformation. The microstructure in the vertical cross sections shows obviously preferential orientation characteristics: Ti2Ni phases of both alloys grow along the vertical direction, and B19' martensite of Ti50Ni50 alloy has distinct preferential orientation, which results from a large temperature gradient between the top and the bottom of the button ingots during solidification. The microstructure with preferential orientation induces the anisotropic NTE behavior of the samples.

Genome Analysis of Listeria monocytogenes Sequence Type 8 Strains Persisting in Salmon and Poultry Processing Environments and Comparison with Related Strains

PubMed Central

Fagerlund, Annette; Langsrud, Solveig; Schirmer, Bjørn C. T.; Møretrø, Trond; Heir, Even

2016-01-01

Listeria monocytogenes is an important foodborne pathogen responsible for the disease listeriosis, and can be found throughout the environment, in many foods and in food processing facilities. The main cause of listeriosis is consumption of food contaminated from sources in food processing environments. Persistence in food processing facilities has previously been shown for the L. monocytogenes sequence type (ST) 8 subtype. In the current study, five ST8 strains were subjected to whole-genome sequencing and compared with five additionally available ST8 genomes, allowing comparison of strains from salmon, poultry and cheese industry, in addition to a human clinical isolate. Genome-wide analysis of single-nucleotide polymorphisms (SNPs) confirmed that almost identical strains were detected in a Danish salmon processing plant in 1996 and in a Norwegian salmon processing plant in 2001 and 2011. Furthermore, we show that L. monocytogenes ST8 was likely to have been transferred between two poultry processing plants as a result of relocation of processing equipment. The SNP data were used to infer the phylogeny of the ST8 strains, separating them into two main genetic groups. Within each group, the plasmid and prophage content was almost entirely conserved, but between groups, these sequences showed strong divergence. The accessory genome of the ST8 strains harbored genetic elements which could be involved in rendering the ST8 strains resilient to incoming mobile genetic elements. These included two restriction-modification loci, one of which was predicted to show phase variable recognition sequence specificity through site-specific domain shuffling. Analysis indicated that the ST8 strains harbor all important known L. monocytogenes virulence factors, and ST8 strains are commonly identified as the causative agents of invasive listeriosis. Therefore, the persistence of this L. monocytogenes subtype in food processing facilities poses a significant concern for food safety. PMID:26953695

Lactococcus lactis Metabolism and Gene Expression during Growth on Plant Tissues

PubMed Central

Golomb, Benjamin L.

2014-01-01

Lactic acid bacteria have been isolated from living, harvested, and fermented plant materials; however, the adaptations these bacteria possess for growth on plant tissues are largely unknown. In this study, we investigated plant habitat-specific traits of Lactococcus lactis during growth in an Arabidopsis thaliana leaf tissue lysate (ATL). L. lactis KF147, a strain originally isolated from plants, exhibited a higher growth rate and reached 7.9-fold-greater cell densities during growth in ATL than the dairy-associated strain L. lactis IL1403. Transcriptome profiling (RNA-seq) of KF147 identified 853 induced and 264 repressed genes during growth in ATL compared to that in GM17 laboratory culture medium. Genes induced in ATL included those involved in the arginine deiminase pathway and a total of 140 carbohydrate transport and metabolism genes, many of which are involved in xylose, arabinose, cellobiose, and hemicellulose metabolism. The induction of those genes corresponded with L. lactis KF147 nutrient consumption and production of metabolic end products in ATL as measured by gas chromatography-time of flight mass spectrometry (GC-TOF/MS) untargeted metabolomic profiling. To assess the importance of specific plant-inducible genes for L. lactis growth in ATL, xylose metabolism was targeted for gene knockout mutagenesis. Wild-type L. lactis strain KF147 but not an xylA deletion mutant was able to grow using xylose as the sole carbon source. However, both strains grew to similarly high levels in ATL, indicating redundancy in L. lactis carbohydrate metabolism on plant tissues. These findings show that certain strains of L. lactis are well adapted for growth on plants and possess specific traits relevant for plant-based food, fuel, and feed fermentations. PMID:25384484

A complex of serine protease genes expressed preferentially in cytotoxic T-lymphocytes is closely linked to the T-cell receptor alpha- and delta-chain genes on mouse chromosome 14.

PubMed

Crosby, J L; Bleackley, R C; Nadeau, J H

1990-02-01

A complex of genes encoding serine proteases that are preferentially expressed in cytotoxic T-cells was shown to be closely linked to the T-cell receptor alpha- and delta-chain genes on mouse chromosome 14. A striking difference in recombination frequencies among linkage crosses was reported. Two genes, Np-1 and Tcra, which fail to recombine in crosses involving conventional strains of mice, were shown to recombine readily in interspecific crosses involving Mus spretus. This difference in recombination frequency suggests chromosomal rearrangements that suppress recombination in conventional crosses, recombination hot spots in interspecific crosses, or selection against recombinant haplotypes during development of recombinant inbred strains. Finally, a mutation called disorganization, which is located near the serine protease complex, is of considerable interest because it causes an extraordinarily wide variety of congenital defects. Because of the involvement of serine protease loci in several homeotic mutations in Drosophila, disorganization must be considered a candidate for a mutation in a serine protease-encoding gene.

Physiological integration modifies δ15N in the clonal plant Fragaria vesca, suggesting preferential transport of nitrogen to water-stressed offspring.

PubMed

Roiloa, S R; Antelo, B; Retuerto, R

2014-08-01

One of the most striking attributes of clonal plants is their capacity for physiological integration, which enables movement of essential resources between connected ramets. This study investigated the capacity of physiological integration to buffer differences in resource availability experienced by ramets of the clonal wild strawberry plant, Fragaria vesca. Specifically, a study was made of the responses of connected and severed offspring ramets growing in environments with different water availability conditions (well watered or water stressed) and nitrogen forms (nitrate or ammonium). The experimental design consisted of three factors, 'integration' (connected, severed) 'water status' (well watered, water stressed) and 'nitrogen form' (nitrate, ammonium), applied in a pot experiment. The effects of physiological integration were studied by analysing photochemical efficiency, leaf spectral reflectance, photosynthesis and carbon and nitrogen isotope discrimination, the last of which has been neglected in previous studies. Physiological integration buffered the stress caused by water deprivation. As a consequence, survival was improved in water-stressed offspring ramets that remained connected to their parent plants. The nitrogen isotope composition (δ(15)N) values in the connected water-stressed ramets were similar to those in ramets in the ammonium treatment; however, δ(15)N values in connected well-watered ramets were similar to those in the nitrate treatment. The results also demonstrated the benefit of integration for offspring ramets in terms of photochemical activity and photosynthesis. This is the first study in which carbon and nitrogen isotopic discrimination has been used to detect physiological integration in clonal plants. The results for nitrogen isotope composition represent the first evidence of preferential transport of a specific form of nitrogen to compensate for stressful conditions experienced by a member clone. Water consumption was lower in plants supplied with ammonium than in plants supplied with nitrate, and therefore preferential transport of ammonium from parents to water-stressed offspring could potentially optimize the water use of the whole clone. © The Author 2014. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Xylose fermentation efficiency and inhibitor tolerance of the recombinant industrial Saccharomyces cerevisiae strain NAPX37.

PubMed

Li, Yun-Cheng; Mitsumasu, Kanako; Gou, Zi-Xi; Gou, Min; Tang, Yue-Qin; Li, Guo-Ying; Wu, Xiao-Lei; Akamatsu, Takashi; Taguchi, Hisataka; Kida, Kenji

2016-02-01

Industrial yeast strains with good xylose fermentation ability and inhibitor tolerance are important for economical lignocellulosic bioethanol production. The flocculating industrial Saccharomyces cerevisiae strain NAPX37, harboring the xylose reductase-xylitol dehydrogenase (XR-XDH)-based xylose metabolic pathway, displayed efficient xylose fermentation during batch and continuous fermentation. During batch fermentation, the xylose consumption rates at the first 36 h were similar (1.37 g/L/h) when the initial xylose concentrations were 50 and 75 g/L, indicating that xylose fermentation was not inhibited even when the xylose concentration was as high as 75 g/L. The presence of glucose, at concentrations of up to 25 g/L, did not affect xylose consumption rate at the first 36 h. Strain NAPX37 showed stable xylose fermentation capacity during continuous ethanol fermentation using xylose as the sole sugar, for almost 1 year. Fermentation remained stable at a dilution rate of 0.05/h, even though the xylose concentration in the feed was as high as 100 g/L. Aeration rate, xylose concentration, and MgSO4 concentration were found to affect xylose consumption and ethanol yield. When the xylose concentration in the feed was 75 g/L, a high xylose consumption rate of 6.62 g/L/h and an ethanol yield of 0.394 were achieved under an aeration rate of 0.1 vvm, dilution rate of 0.1/h, and 5 mM MgSO4. In addition, strain NAPX37 exhibited good tolerance to inhibitors such as weak acids, furans, and phenolics during xylose fermentation. These findings indicate that strain NAPX37 is a promising candidate for application in the industrial production of lignocellulosic bioethanol.

Comparing the xylose reductase/xylitol dehydrogenase and xylose isomerase pathways in arabinose and xylose fermenting Saccharomyces cerevisiae strains

PubMed Central

Bettiga, Maurizio; Hahn-Hägerdal, Bärbel; Gorwa-Grauslund, Marie F

2008-01-01

Background Ethanolic fermentation of lignocellulosic biomass is a sustainable option for the production of bioethanol. This process would greatly benefit from recombinant Saccharomyces cerevisiae strains also able to ferment, besides the hexose sugar fraction, the pentose sugars, arabinose and xylose. Different pathways can be introduced in S. cerevisiae to provide arabinose and xylose utilisation. In this study, the bacterial arabinose isomerase pathway was combined with two different xylose utilisation pathways: the xylose reductase/xylitol dehydrogenase and xylose isomerase pathways, respectively, in genetically identical strains. The strains were compared with respect to aerobic growth in arabinose and xylose batch culture and in anaerobic batch fermentation of a mixture of glucose, arabinose and xylose. Results The specific aerobic arabinose growth rate was identical, 0.03 h-1, for the xylose reductase/xylitol dehydrogenase and xylose isomerase strain. The xylose reductase/xylitol dehydrogenase strain displayed higher aerobic growth rate on xylose, 0.14 h-1, and higher specific xylose consumption rate in anaerobic batch fermentation, 0.09 g (g cells)-1 h-1 than the xylose isomerase strain, which only reached 0.03 h-1 and 0.02 g (g cells)-1h-1, respectively. Whereas the xylose reductase/xylitol dehydrogenase strain produced higher ethanol yield on total sugars, 0.23 g g-1 compared with 0.18 g g-1 for the xylose isomerase strain, the xylose isomerase strain achieved higher ethanol yield on consumed sugars, 0.41 g g-1 compared with 0.32 g g-1 for the xylose reductase/xylitol dehydrogenase strain. Anaerobic fermentation of a mixture of glucose, arabinose and xylose resulted in higher final ethanol concentration, 14.7 g l-1 for the xylose reductase/xylitol dehydrogenase strain compared with 11.8 g l-1 for the xylose isomerase strain, and in higher specific ethanol productivity, 0.024 g (g cells)-1 h-1 compared with 0.01 g (g cells)-1 h-1 for the xylose reductase/xylitol dehydrogenase strain and the xylose isomerase strain, respectively. Conclusion The combination of the xylose reductase/xylitol dehydrogenase pathway and the bacterial arabinose isomerase pathway resulted in both higher pentose sugar uptake and higher overall ethanol production than the combination of the xylose isomerase pathway and the bacterial arabinose isomerase pathway. Moreover, the flux through the bacterial arabinose pathway did not increase when combined with the xylose isomerase pathway. This suggests that the low activity of the bacterial arabinose pathway cannot be ascribed to arabitol formation via the xylose reductase enzyme. PMID:18947407

Identification of LukPQ, a novel, equid-adapted leukocidin of Staphylococcus aureus

PubMed Central

Koop, Gerrit; Vrieling, Manouk; Storisteanu, Daniel M. L.; Lok, Laurence S. C.; Monie, Tom; van Wigcheren, Glenn; Raisen, Claire; Ba, Xiaoliang; Gleadall, Nicholas; Hadjirin, Nazreen; Timmerman, Arjen J.; Wagenaar, Jaap A.; Klunder, Heleen M.; Fitzgerald, J. Ross; Zadoks, Ruth; Paterson, Gavin K.; Torres, Carmen; Waller, Andrew S.; Loeffler, Anette; Loncaric, Igor; Hoet, Armando E.; Bergström, Karin; De Martino, Luisa; Pomba, Constança; de Lencastre, Hermínia; Ben Slama, Karim; Gharsa, Haythem; Richardson, Emily J.; Chilvers, Edwin R.; de Haas, Carla; van Kessel, Kok; van Strijp, Jos A. G.; Harrison, Ewan M.; Holmes, Mark A.

2017-01-01

Bicomponent pore-forming leukocidins are a family of potent toxins secreted by Staphylococcus aureus, which target white blood cells preferentially and consist of an S- and an F-component. The S-component recognizes a receptor on the host cell, enabling high-affinity binding to the cell surface, after which the toxins form a pore that penetrates the cell lipid bilayer. Until now, six different leukocidins have been described, some of which are host and cell specific. Here, we identify and characterise a novel S. aureus leukocidin; LukPQ. LukPQ is encoded on a 45 kb prophage (ΦSaeq1) found in six different clonal lineages, almost exclusively in strains cultured from equids. We show that LukPQ is a potent and specific killer of equine neutrophils and identify equine-CXCRA and CXCR2 as its target receptors. Although the S-component (LukP) is highly similar to the S-component of LukED, the species specificity of LukPQ and LukED differs. By forming non-canonical toxin pairs, we identify that the F-component contributes to the observed host tropism of LukPQ, thereby challenging the current paradigm that leukocidin specificity is driven solely by the S-component. PMID:28106142

An In Vitro Evaluation of Antioxidant and Colonic Microbial Profile Levels following Mushroom Consumption

PubMed Central

Vamanu, Emanuel; Avram, Ionela; Nita, Sultana

2013-01-01

The biological activity of mushroom consumption is achieved by the antioxidant effect of constituent biomolecules released during digestion. In the following study, the consumption of mushroom fungi was determined to increase the number of Lactobacillus and Bifidobacterium strains within the colon. The main phenolic antioxidant compounds identified were both gentisic and homogentisic acids. Moreover, the flavonoid catechin as well as a significant amount of δ- and γ-tocopherols was determined. The amount of Lactobacillus and Bifidobacterium strains from different sections of the human colon was significantly correlated with levels of antioxidative biomolecules. The experimental data clearly demonstrate a significant impact of mushroom consumption on the fermentative function of microorganisms in the human colon, resulting in the homeostasis of normal physiological colonic functions. PMID:24027755

Simultaneous consumption of pentose and hexose sugars: an optimal microbial phenotype for efficient fermentation of lignocellulosic biomass.

PubMed

Kim, Jae-Han; Block, David E; Mills, David A

2010-11-01

Lignocellulosic biomass is an attractive carbon source for bio-based fuel and chemical production; however, its compositional heterogeneity hinders its commercial use. Since most microbes possess carbon catabolite repression (CCR), mixed sugars derived from the lignocellulose are consumed sequentially, reducing the efficacy of the overall process. To overcome this barrier, microbes that exhibit the simultaneous consumption of mixed sugars have been isolated and/or developed and evaluated for the lignocellulosic biomass utilization. Specific strains of Escherichia coli, Saccharomyces cerevisiae, and Zymomonas mobilis have been engineered for simultaneous glucose and xylose utilization via mutagenesis or introduction of a xylose metabolic pathway. Other microbes, such as Lactobacillus brevis, Lactobacillus buchneri, and Candida shehatae possess a relaxed CCR mechanism, showing simultaneous consumption of glucose and xylose. By exploiting CCR-negative phenotypes, various integrated processes have been developed that incorporate both enzyme hydrolysis of lignocellulosic material and mixed sugar fermentation, thereby enabling greater productivity and fermentation efficacy.

Simultaneous consumption of pentose and hexose sugars: an optimal microbial phenotype for efficient fermentation of lignocellulosic biomass

PubMed Central

Kim, Jae-Han; Block, David E.

2010-01-01

Lignocellulosic biomass is an attractive carbon source for bio-based fuel and chemical production; however, its compositional heterogeneity hinders its commercial use. Since most microbes possess carbon catabolite repression (CCR), mixed sugars derived from the lignocellulose are consumed sequentially, reducing the efficacy of the overall process. To overcome this barrier, microbes that exhibit the simultaneous consumption of mixed sugars have been isolated and/or developed and evaluated for the lignocellulosic biomass utilization. Specific strains of Escherichia coli, Saccharomyces cerevisiae, and Zymomonas mobilis have been engineered for simultaneous glucose and xylose utilization via mutagenesis or introduction of a xylose metabolic pathway. Other microbes, such as Lactobacillus brevis, Lactobacillus buchneri, and Candida shehatae possess a relaxed CCR mechanism, showing simultaneous consumption of glucose and xylose. By exploiting CCR-negative phenotypes, various integrated processes have been developed that incorporate both enzyme hydrolysis of lignocellulosic material and mixed sugar fermentation, thereby enabling greater productivity and fermentation efficacy. PMID:20838789

Increased accumulation of polyhydroxybutyrate in divergent cyanobacteria under nutrient-deprived photoautotrophy: An efficient conversion of solar energy and carbon dioxide to polyhydroxybutyrate by Calothrix scytonemicola TISTR 8095.

PubMed

Kaewbai-Ngam, Auratai; Incharoensakdi, Aran; Monshupanee, Tanakarn

2016-07-01

The cellular PHB content was determined in 137 strains of cyanobacteria representing 88 species in 26 genera under six photoautotrophic nutrient conditions. One hundred and thirty-four strains were PHB producers. The PHB contents of these 134 strains were subtle under normal growth condition, but were significantly increased in 63 strains under nitrogen deprivation (-N), a higher frequency than with phosphate and/or potassium and all-nutrient deprivation. A high PHB accumulation was not associated with any particular evolutionary groups, but was strain specific. The filamentous Calothrix scytonemicola TISTR 8095 produced 356.5±63.4mg/L PHB under -N from a biomass of 1396.6±66.1mg/L, giving a PHB content of 25.4±3.5% (w/w dry weight). This PHB productivity is equivalent to the CO2 consumption of 729.2±129.8mg/L. The maximum energy conversion from solar energy to PHB obtained by C. scytonemicola TISTR 8095 was 1.42±0.30%. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mechanism of protein precipitation and stabilization by co-solvents

NASA Astrophysics Data System (ADS)

Timasheff, Serge N.; Arakawa, Tsutomu

1988-07-01

The interactions between proteins and a number of substances which, when present at high concentration, stabilize or precipitate proteins, have been analyzed in terms of the preferential interactions of these co-solvents with proteins. In all cases, stabilization or precipitation was accompanied by preferential exclusion of the co-solvent from the immediate domain of the protein, i.e., preferential hydration of the protein. This means that addition of the co-solvent to the aqueous protein solution increased the chemical potentials of both components. The thermodynamic interaction parameters derived from such data make it possible to calculate the salting out constant, Ks, as well as to construct a phase isotherm for any given solvent mixture which indicates the limiting protein solubility. The salting-out effect can be decomposed into contributions from non-specific preferential exclusion and specific binding of the ligand to the protein, the balance leading to solubilization or precipitation. In reactions, such as denaturation, the effect of co-solvent on the reaction depends on the difference in the preferential interactions of the two end states of the protein. Principal sources of preferential exclusion have been identified as steric exclusion, increase of the surface tension of water by the co-solvent, repulsion by charged loci on the protein and solvophobicity.

Preferential sites for InAsP/InP quantum wire nucleation using molecular dynamics

NASA Astrophysics Data System (ADS)

Nuñez-Moraleda, Bernardo; Pizarro, Joaquin; Guerrero, Elisa; Guerrero-Lebrero, Maria P.; Yáñez, Andres; Molina, Sergio Ignacio; Galindo, Pedro Luis

2014-11-01

In this paper, stress fields at the surface of the capping layer of self-assembled InAsP quantum wires grown on an InP (001) substrate have been determined from atomistic models using molecular dynamics and Stillinger-Weber potentials. To carry out these calculations, the quantum wire compositional distribution was extracted from previous works, where the As and P distributions were determined by electron energy loss spectroscopy and high-resolution aberration-corrected Z-contrast imaging. Preferential sites for the nucleation of wires on the surface of the capping layer were studied and compared with (i) previous simulations using finite element analysis to solve anisotropic elastic theory equations and (ii) experimentally measured locations of stacked wires. Preferential nucleation sites of stacked wires were determined by the maximum stress location at the MD model surface in good agreement with experimental results and those derived from finite element analysis. This indicates that MD simulations based on empirical potentials provide a suitable and flexible tool to study strain dependent atom processes.

Fermentation of Acid-pretreated Corn Stover to Ethanol Without Detoxification Using Pichia stipitis

NASA Astrophysics Data System (ADS)

Agbogbo, Frank K.; Haagensen, Frank D.; Milam, David; Wenger, Kevin S.

In this work, the effect of adaptation on P. stipitis fermentation using acidpretreated corn stover hydrolyzates without detoxification was examined. Two different types of adaptation were employed, liquid hydrolyzate and solid state agar adaptation. Fermentation of 12.5% total solids undetoxified acid-pretreated corn stover was performed in shake flasks at different rotation speeds. At low rotation speed (100 rpm), both liquid hydrolyzate and solid agar adaptation highly improved the sugar consumption rate as well as ethanol production rate compared to the wild-type strains. The fermentation rate was higher for solid agar-adapted strains compared to liquid hydrolyzate-adapted strains. At a higher rotation speed (150 rpm), there was a faster sugar consumption and ethanol production for both the liquid-adapted and the wild-type strains. However, improvements in the fermentation rate between the liquid-adapted and wild strains were less pronounced at the high rotation speed.

Natural variation in non-coding regions underlying phenotypic diversity in budding yeast

PubMed Central

Salinas, Francisco; de Boer, Carl G.; Abarca, Valentina; García, Verónica; Cuevas, Mara; Araos, Sebastian; Larrondo, Luis F.; Martínez, Claudio; Cubillos, Francisco A.

2016-01-01

Linkage mapping studies in model organisms have typically focused their efforts in polymorphisms within coding regions, ignoring those within regulatory regions that may contribute to gene expression variation. In this context, differences in transcript abundance are frequently proposed as a source of phenotypic diversity between individuals, however, until now, little molecular evidence has been provided. Here, we examined Allele Specific Expression (ASE) in six F1 hybrids from Saccharomyces cerevisiae derived from crosses between representative strains of the four main lineages described in yeast. ASE varied between crosses with levels ranging between 28% and 60%. Part of the variation in expression levels could be explained by differences in transcription factors binding to polymorphic cis-regulations and to differences in trans-activation depending on the allelic form of the TF. Analysis on highly expressed alleles on each background suggested ASN1 as a candidate transcript underlying nitrogen consumption differences between two strains. Further promoter allele swap analysis under fermentation conditions confirmed that coding and non-coding regions explained aspartic and glutamic acid consumption differences, likely due to a polymorphism affecting Uga3 binding. Together, we provide a new catalogue of variants to bridge the gap between genotype and phenotype. PMID:26898953

Neural basis of reward anticipation and its genetic determinants.

PubMed

Jia, Tianye; Macare, Christine; Desrivières, Sylvane; Gonzalez, Dante A; Tao, Chenyang; Ji, Xiaoxi; Ruggeri, Barbara; Nees, Frauke; Banaschewski, Tobias; Barker, Gareth J; Bokde, Arun L W; Bromberg, Uli; Büchel, Christian; Conrod, Patricia J; Dove, Rachel; Frouin, Vincent; Gallinat, Jürgen; Garavan, Hugh; Gowland, Penny A; Heinz, Andreas; Ittermann, Bernd; Lathrop, Mark; Lemaitre, Hervé; Martinot, Jean-Luc; Paus, Tomáš; Pausova, Zdenka; Poline, Jean-Baptiste; Rietschel, Marcella; Robbins, Trevor; Smolka, Michael N; Müller, Christian P; Feng, Jianfeng; Rothenfluh, Adrian; Flor, Herta; Schumann, Gunter

2016-04-05

Dysfunctional reward processing is implicated in various mental disorders, including attention deficit hyperactivity disorder (ADHD) and addictions. Such impairments might involve different components of the reward process, including brain activity during reward anticipation. We examined brain nodes engaged by reward anticipation in 1,544 adolescents and identified a network containing a core striatal node and cortical nodes facilitating outcome prediction and response preparation. Distinct nodes and functional connections were preferentially associated with either adolescent hyperactivity or alcohol consumption, thus conveying specificity of reward processing to clinically relevant behavior. We observed associations between the striatal node, hyperactivity, and the vacuolar protein sorting-associated protein 4A (VPS4A) gene in humans, and the causal role of Vps4 for hyperactivity was validated in Drosophila Our data provide a neurobehavioral model explaining the heterogeneity of reward-related behaviors and generate a hypothesis accounting for their enduring nature.

Neural basis of reward anticipation and its genetic determinants

PubMed Central

Jia, Tianye; Macare, Christine; Desrivières, Sylvane; Gonzalez, Dante A.; Tao, Chenyang; Ji, Xiaoxi; Ruggeri, Barbara; Nees, Frauke; Banaschewski, Tobias; Barker, Gareth J.; Bokde, Arun L. W.; Bromberg, Uli; Büchel, Christian; Conrod, Patricia J.; Dove, Rachel; Gallinat, Jürgen; Garavan, Hugh; Gowland, Penny A.; Heinz, Andreas; Ittermann, Bernd; Lathrop, Mark; Lemaitre, Hervé; Martinot, Jean-Luc; Paus, Tomáš; Pausova, Zdenka; Poline, Jean-Baptiste; Rietschel, Marcella; Robbins, Trevor; Müller, Christian P.; Feng, Jianfeng; Rothenfluh, Adrian; Flor, Herta; Schumann, Gunter

2016-01-01

Dysfunctional reward processing is implicated in various mental disorders, including attention deficit hyperactivity disorder (ADHD) and addictions. Such impairments might involve different components of the reward process, including brain activity during reward anticipation. We examined brain nodes engaged by reward anticipation in 1,544 adolescents and identified a network containing a core striatal node and cortical nodes facilitating outcome prediction and response preparation. Distinct nodes and functional connections were preferentially associated with either adolescent hyperactivity or alcohol consumption, thus conveying specificity of reward processing to clinically relevant behavior. We observed associations between the striatal node, hyperactivity, and the vacuolar protein sorting-associated protein 4A (VPS4A) gene in humans, and the causal role of Vps4 for hyperactivity was validated in Drosophila. Our data provide a neurobehavioral model explaining the heterogeneity of reward-related behaviors and generate a hypothesis accounting for their enduring nature. PMID:27001827

Preferential Interaction of Na+ over K+ to Carboxylate-functionalized Silver Nanoparticles

EPA Science Inventory

Elucidating mechanistic interactions between specific ions (Na+/ K+) and nanoparticle surfaces to alter particle stability in polar media has received little attention. We investigated relative preferential binding of Na+ and K+ to carboxylate-functionalized silver nanoparticles ...

Genome‐scale diversity and niche adaptation analysis of Lactococcus lactis by comparative genome hybridization using multi‐strain arrays

PubMed Central

Siezen, Roland J.; Bayjanov, Jumamurat R.; Felis, Giovanna E.; van der Sijde, Marijke R.; Starrenburg, Marjo; Molenaar, Douwe; Wels, Michiel; van Hijum, Sacha A. F. T.; van Hylckama Vlieg, Johan E. T.

2011-01-01

Summary Lactococcus lactis produces lactic acid and is widely used in the manufacturing of various fermented dairy products. However, the species is also frequently isolated from non‐dairy niches, such as fermented plant material. Recently, these non‐dairy strains have gained increasing interest, as they have been described to possess flavour‐forming activities that are rarely found in dairy isolates and have diverse metabolic properties. We performed an extensive whole‐genome diversity analysis on 39 L. lactis strains, isolated from dairy and plant sources. Comparative genome hybridization analysis with multi‐strain microarrays was used to assess presence or absence of genes and gene clusters in these strains, relative to all L. lactis sequences in public databases, whereby chromosomal and plasmid‐encoded genes were computationally analysed separately. Nearly 3900 chromosomal orthologous groups (chrOGs) were defined on basis of four sequenced chromosomes of L. lactis strains (IL1403, KF147, SK11, MG1363). Of these, 1268 chrOGs are present in at least 35 strains and represent the presently known core genome of L. lactis, and 72 chrOGs appear to be unique for L. lactis. Nearly 600 and 400 chrOGs were found to be specific for either the subspecies lactis or subspecies cremoris respectively. Strain variability was found in presence or absence of gene clusters related to growth on plant substrates, such as genes involved in the consumption of arabinose, xylan, α‐galactosides and galacturonate. Further niche‐specific differences were found in gene clusters for exopolysaccharides biosynthesis, stress response (iron transport, osmotolerance) and bacterial defence mechanisms (nisin biosynthesis). Strain variability of functions encoded on known plasmids included proteolysis, lactose fermentation, citrate uptake, metal ion resistance and exopolysaccharides biosynthesis. The present study supports the view of L. lactis as a species with a very flexible genome. PMID:21338475

Risk of Vibrio transmission linked to the consumption of crustaceans in coastal towns of Côte d'Ivoire.

PubMed

Traoré, S G; Bonfoh, B; Krabi, R; Odermatt, P; Utzinger, J; Rose, K-N; Tanner, M; Frey, J; Quilici, M-L; Koussémon, M

2012-06-01

The purpose of this study was to assess the risk of Vibrio spp. transmission from crustaceans to humans in two coastal towns of Côte d'Ivoire. Bacteriologic analysis was performed on 322 crustacean samples obtained from six markets in Abidjan and one in Dabou. Suspected Vibrio colonies were identified by morphological, cultural, biochemical, and molecular tests and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. PCR assays were used to further characterize Vibrio strains. A survey on consumption of crustaceans was conducted among 120 randomly selected households in Abidjan. Overall, Vibrio spp. were isolated from 7.8% of the crustacean samples studied, at levels as high as 6.3 log CFU/g. Of the Vibrio strains identified, 40% were V. alginolyticus, 36% were V. parahaemolyticus, and 24% were nontoxigenic V. cholerae; the latter two species can cause mild to severe forms of seafood-associated gastroenteritis. Among interviewed households, 11.7% reported daily consumption of crustaceans, confirming the high probability of exposure of human population to Vibrio spp., and 7.5% reported symptoms of food poisoning after consumption of crustaceans. The absence of genes encoding major virulence factors in the studied strains, i.e., cholera toxin (ctxA and ctxB) in V. cholerae and thermostable direct hemolysin (tdh) and thermostable direct hemolysin-related hemolysin (trh) in V. parahaemolyticus, does not exclude the possibility of exposure to pathogenic strains. However, human infections are not common because most households (96.7%) boil crustaceans, usually for at least 45 min (85.9% of households) before consumption.

Integrated approach for selecting efficient Saccharomyces cerevisiae for industrial lignocellulosic fermentations: Importance of yeast chassis linked to process conditions.

PubMed

Costa, Carlos E; Romaní, Aloia; Cunha, Joana T; Johansson, Björn; Domingues, Lucília

2017-03-01

In this work, four robust yeast chassis isolated from industrial environments were engineered with the same xylose metabolic pathway. The recombinant strains were physiologically characterized in synthetic xylose and xylose-glucose medium, on non-detoxified hemicellulosic hydrolysates of fast-growing hardwoods (Eucalyptus and Paulownia) and agricultural residues (corn cob and wheat straw) and on Eucalyptus hydrolysate at different temperatures. Results show that the co-consumption of xylose-glucose was dependent on the yeast background. Moreover, heterogeneous results were obtained among different hydrolysates and temperatures for each individual strain pointing to the importance of designing from the very beginning a tailor-made yeast considering the specific raw material and process. Copyright © 2016 Elsevier Ltd. All rights reserved.

Conifer Monoterpene Chemistry during an Outbreak Enhances Consumption and Immune Response of an Eruptive Folivore.

PubMed

Trowbridge, Amy M; Bowers, M Deane; Monson, Russell K

2016-12-01

Changes in the chemical composition of plant defense compounds during herbivory can impact herbivore resource allocation patterns and thereby herbivore survival, growth, and immune response against endoparasitoid infection. Few studies have investigated folivore responses to changes in plant chemistry that occur under outbreak conditions in mature conifer systems. Using data from an earlier observational field study, we carried out laboratory bioassays to test how variation in monoterpenes in piñon pine trees (Pinus edulis, Pinaceae) during an outbreak affects growth, consumption, and immune response of a specialist herbivore, the Southwestern tiger moth (Lophocampa ingens, Arctiidae). Larvae were fed on artificial diets containing four monoterpenes at concentrations that mimicked those observed in undamaged and herbivore-damaged trees in situ during an outbreak. Damaged trees contained 30% lower total monoterpene concentrations, likely reflecting volatile losses as observed in a previous field study Trowbridge et al. (Ecology 95:1591-1603, Trowbridge et al. 2014). Herbivores reared on diets mimicking terpene concentrations in the needles of damaged trees exhibited an approximately 60% increase in consumption relative to larvae reared on diets characteristic of trees without herbivore damage. Higher consumption was accompanied by a 40% increase in immune response with no change in growth rate. These observations suggest preferential resource allocation towards immunity and/or a strong genetic component that determines growth under these conditions. These outcomes, which favor the herbivore, point to: (i) a potential positive feedback mechanism that may increase L. ingens's chance of escaping parasitism during the early phases of an outbreak; and (ii) the important role of monoterpenes in mediating conifer-folivore interactions specifically for P. edulis, which has suffered large-scale drought-induced mortality events exacerbated by the presence of insects.

Dynamics of fecal microbiota in hospitalized elderly fed probiotic LKM512 yogurt.

PubMed

Matsumoto, Mitsuharu; Sakamoto, Mitsuo; Benno, Yoshimi

2009-08-01

The comprehensive dynamics of intestinal microbiota including uncultured bacteria in response to probiotic consumption have not been well studied. The aims of this study were twofold: firstly to analyze the impact on intestinal microbiota of yogurt fermented by Bifidobacterium animalis subsp. lactis LKM512, Lactobacillus delbrueckii subsp. bulgaricus LKM1759, and Streptococcus thermophilus LKM1742 (LKM512 yogurt) and placebo fermented by these lactic acid bacterial strains without LKM512; and secondly to investigate the changes in intestinal microbiota that influence the concentration of PA, one of the beneficial metabolites produced by bacteria in the intestine. The LKM512 yogurt/placebo trial was performed in six hospitalized elderly patients (three men and three women with an average age of 80.3 years) and lasted seven weeks with the following schedule: pre-consumption for one week, LKM512 yogurt consumption for two weeks, washout period for two weeks, and placebo consumption for two weeks. The amount of ingested LKM512 yogurt or placebo was 100 g/day/individual. Fecal samples were analyzed using T-RFLP and real-time PCR. The T-RFLP patterns in five of the six volunteers were changed in a similar fashion by LKM512 yogurt consumption, although these patterns were individually changed following consumption of placebo. It was confirmed that B. animalis subsp. lactis was increased dramatically and Lactobacillus spp. tended to be decreased by LKM512 yogurt consumption. Some indigenous uncultured bacteria were increased and some decreased by LKM512 yogurt/placebo consumption. The similar changes in the intestinal microbiota of the elderly caused by consumption of the LKM512 yogurt were found to be influenced by the LKM512 strain itself, and not by the lactic acid bacteria in the yogurt. Moreover, this study suggests that the increase in intestinal PA concentrations caused by LKM512 yogurt consumption is probably dependent on the LKM512 strain colonizing the intestine.

Season-Specific Occurrence of Potentially Pathogenic Vibrio spp. on the Southern Coast of South Korea.

PubMed

Di, Doris Y W; Lee, Anna; Jang, Jeonghwan; Han, Dukki; Hur, Hor-Gil

2017-02-01

Vibrio species are widely distributed in warm estuarine and coastal environments, and they can infect humans through the consumption of raw and mishandled contaminated seafood. In this study, we aimed to isolate and observe the distribution of enteropathogenic Vibrio spp. from environments of the southern coast of South Korea over a season cycle. A total of 10,983 isolates of Vibrio spp. were obtained from tidal water and mud samples over a 1-year period from five sampling sites along the southwest coast of South Korea. We found that Vibrio alginolyticus (n = 6,262) and Vibrio parahaemolyticus (n = 1,757) were ubiquitous in both tidal water and mud year round, whereas Vibrio cholerae (n = 24) and Vibrio vulnificus (n = 130) were seasonally specific to summer. While all V. cholerae isolates were nontoxigenic (non-O1 and non-O139), more than 88% of V. vulnificus isolates possessed the virulence factor elastolytic protease (encoded by vvp). Interestingly, V. parahaemolyticus, which was omnipresent in all seasons, contained the virulence factors thermostable direct hemolysin (encoded by tdh) and thermostable direct hemolysin-related hemolysin (encoded by trh) in larger amounts in June (29 trh-positive strains) and September (14 tdh-, 36 trh-, and 12 tdh- and trh-positive strains) than in December (4 trh-positive strains) and February (3 tdh-positive strains), and virulence factors were absent from isolates detected in April. To understand why virulence factors were detected only in the warm season and were absent in the cold season although the locations are static, long-term monitoring and particularly seasonal study are necessary. The presence of enteropathogenic Vibrio species (Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus), which cause acute diarrheal infection, septicemia, and wound infections upon ingestion through food and water, is usually associated with temperature. The World Health Organization (WHO) has estimated that there are 1.4 to 4.3 million cases and 28,000 to 142,000 deaths per year worldwide caused by cholera disease. In South Korea alone, consumption is as much as 52.4 kg of fish and shellfish per year per capita. Our findings suggested that seasonally specific acceleration of these possible pathogenic Vibrio spp. may threaten seafood safety and increase the risk of illness in South Korea, where local people consume raw fish during warmer months. Copyright © 2017 American Society for Microbiology.

Season-Specific Occurrence of Potentially Pathogenic Vibrio spp. on the Southern Coast of South Korea

PubMed Central

Di, Doris Y. W.; Lee, Anna; Jang, Jeonghwan; Han, Dukki

2016-01-01

ABSTRACT Vibrio species are widely distributed in warm estuarine and coastal environments, and they can infect humans through the consumption of raw and mishandled contaminated seafood. In this study, we aimed to isolate and observe the distribution of enteropathogenic Vibrio spp. from environments of the southern coast of South Korea over a season cycle. A total of 10,983 isolates of Vibrio spp. were obtained from tidal water and mud samples over a 1-year period from five sampling sites along the southwest coast of South Korea. We found that Vibrio alginolyticus (n = 6,262) and Vibrio parahaemolyticus (n = 1,757) were ubiquitous in both tidal water and mud year round, whereas Vibrio cholerae (n = 24) and Vibrio vulnificus (n = 130) were seasonally specific to summer. While all V. cholerae isolates were nontoxigenic (non-O1 and non-O139), more than 88% of V. vulnificus isolates possessed the virulence factor elastolytic protease (encoded by vvp). Interestingly, V. parahaemolyticus, which was omnipresent in all seasons, contained the virulence factors thermostable direct hemolysin (encoded by tdh) and thermostable direct hemolysin-related hemolysin (encoded by trh) in larger amounts in June (29 trh-positive strains) and September (14 tdh-, 36 trh-, and 12 tdh- and trh-positive strains) than in December (4 trh-positive strains) and February (3 tdh-positive strains), and virulence factors were absent from isolates detected in April. To understand why virulence factors were detected only in the warm season and were absent in the cold season although the locations are static, long-term monitoring and particularly seasonal study are necessary. IMPORTANCE The presence of enteropathogenic Vibrio species (Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus), which cause acute diarrheal infection, septicemia, and wound infections upon ingestion through food and water, is usually associated with temperature. The World Health Organization (WHO) has estimated that there are 1.4 to 4.3 million cases and 28,000 to 142,000 deaths per year worldwide caused by cholera disease. In South Korea alone, consumption is as much as 52.4 kg of fish and shellfish per year per capita. Our findings suggested that seasonally specific acceleration of these possible pathogenic Vibrio spp. may threaten seafood safety and increase the risk of illness in South Korea, where local people consume raw fish during warmer months. PMID:27836844

Detection of Toxoplasma gondii DNA in horse meat from supermarkets in France and performance evaluation of two serological tests.

PubMed

Aroussi, Abdelkrim; Vignoles, Philippe; Dalmay, François; Wimel, Laurence; Dardé, Marie-Laure; Mercier, Aurélien; Ajzenberg, Daniel

2015-01-01

In France, some cases of severe toxoplasmosis have been linked to the consumption of horse meat that had been imported from the American continent where atypical strains of Toxoplasma gondii are more common than in Europe. Many seroprevalence studies are presented in the literature but risk assessment of T. gondii infection after horse meat consumption is not possible in the absence of validated serological tests and the unknown correlation between detection of antibodies against T. gondii and presence of tissue cysts. We performed magnetic-capture polymerase chain reaction (MC-PCR) to detect T. gondii DNA in 231 horse meat samples purchased in supermarkets in France and evaluated the performance and level of agreement of the modified agglutination test (MAT) and enzyme-linked immunosorbent assay (ELISA) in the meat juices. The serological tests lacked sensitivity, specificity, and agreement between them, and there was no correlation with the presence of T. gondii DNA in horse meat, raising concerns about the reliability of T. gondii seroprevalence data in horses from the literature. T. gondii DNA was detected in 43% of horse meat samples but the absence of strain isolation in mice following inoculation of more than 100 horse meat samples suggests a low distribution of cysts in skeletal muscles and a low risk of T. gondii infection associated with horse meat consumption. However, to avoid any risk of toxoplasmosis, thorough cooking of horse meat is recommended. © A. Aroussi et al., published by EDP Sciences, 2015.

Detection of Toxoplasma gondii DNA in horse meat from supermarkets in France and performance evaluation of two serological tests

PubMed Central

Aroussi, Abdelkrim; Vignoles, Philippe; Dalmay, François; Wimel, Laurence; Dardé, Marie-Laure; Mercier, Aurélien; Ajzenberg, Daniel

2015-01-01

In France, some cases of severe toxoplasmosis have been linked to the consumption of horse meat that had been imported from the American continent where atypical strains of Toxoplasma gondii are more common than in Europe. Many seroprevalence studies are presented in the literature but risk assessment of T. gondii infection after horse meat consumption is not possible in the absence of validated serological tests and the unknown correlation between detection of antibodies against T. gondii and presence of tissue cysts. We performed magnetic-capture polymerase chain reaction (MC-PCR) to detect T. gondii DNA in 231 horse meat samples purchased in supermarkets in France and evaluated the performance and level of agreement of the modified agglutination test (MAT) and enzyme-linked immunosorbent assay (ELISA) in the meat juices. The serological tests lacked sensitivity, specificity, and agreement between them, and there was no correlation with the presence of T. gondii DNA in horse meat, raising concerns about the reliability of T. gondii seroprevalence data in horses from the literature. T. gondii DNA was detected in 43% of horse meat samples but the absence of strain isolation in mice following inoculation of more than 100 horse meat samples suggests a low distribution of cysts in skeletal muscles and a low risk of T. gondii infection associated with horse meat consumption. However, to avoid any risk of toxoplasmosis, thorough cooking of horse meat is recommended. PMID:25809058

Purification, characterization, gene cloning and nucleotide sequencing of D: -stereospecific amino acid amidase from soil bacterium: Delftia acidovorans.

PubMed

Hongpattarakere, Tipparat; Komeda, Hidenobu; Asano, Yasuhisa

2005-12-01

The D-amino acid amidase-producing bacterium was isolated from soil samples using an enrichment culture technique in medium broth containing D-phenylalanine amide as a sole source of nitrogen. The strain exhibiting the strongest activity was identified as Delftia acidovorans strain 16. This strain produced intracellular D-amino acid amidase constitutively. The enzyme was purified about 380-fold to homogeneity and its molecular mass was estimated to be about 50 kDa, on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme was active preferentially toward D-amino acid amides rather than their L-counterparts. It exhibited strong amino acid amidase activity toward aromatic amino acid amides including D-phenylalanine amide, D-tryptophan amide and D-tyrosine amide, yet it was not specifically active toward low-molecular-weight D-amino acid amides such as D-alanine amide, L-alanine amide and L-serine amide. Moreover, it was not specifically active toward oligopeptides. The enzyme showed maximum activity at 40 degrees C and pH 8.5 and appeared to be very stable, with 92.5% remaining activity after the reaction was performed at 45 degrees C for 30 min. However, it was mostly inactivated in the presence of phenylmethanesulfonyl fluoride or Cd2+, Ag+, Zn2+, Hg2+ and As3+ . The NH2 terminal and internal amino acid sequences of the enzyme were determined; and the gene was cloned and sequenced. The enzyme gene damA encodes a 466-amino-acid protein (molecular mass 49,860.46 Da); and the deduced amino acid sequence exhibits homology to the D-amino acid amidase from Variovorax paradoxus (67.9% identity), the amidotransferase A subunit from Burkholderia fungorum (50% identity) and other enantioselective amidases.

Atmospheric deposition of nitrogen and sulfur and preferential canopy consumption of nitrate in forests of the Pacific Northwest, USA

Treesearch

Mark E. Fenn; Christopher S. Ross; Susan L. Schilling; William D. Baccus; Michael A. Larrabee; Rebecca A. Lofgren

2013-01-01

Wet,dry and throughfall deposition of N and S were measured for 2 years in three national parks in Washington State:Olympic,Mount Rainier,and North Cascades.Throughfall was measured using ion exchange resin (IER) collectors. A major objective of the study was to evaluate the effectiveness of IER throughfall measurements for monitoring deposition inputs,including...

Human forearm metabolism during progressive starvation.

PubMed

Owen, O E; Reichard, G A

1971-07-01

Forearm muscle metabolism was studied in eight obese subjects after an overnight, 3 and 24 day fast. Arterio-deep-venous differences of oxygen, carbon dioxide, glucose, lactate, pyruvate, free fatty acids, acetoacetate, and beta-hydroxybutyrate with simultaneous forearm blood flow were measured. Rates of metabolite utilization and production were thus estimated. Oxygen consumption and lactate and pyruvate production remained relatively constant at each fasting period. Glucose, initially the major substrate consumed, showed decreased consumption after 3 and 24 days of fasting. Acetoacetate and beta-hydroxybutyrate consumption after an overnight fast was low. At 3 days of fasting with increased arterial concentrations of acetoactate and beta-hydroxybutyrate, consumption of these substrates rose dramatically. At 24 days of fasting, despite further elevation of arterial levels of acetoacetate and beta-hydroxybutyrate, the utilization of acetoacetate did not increase further and if anything decreased, while five out of eight subjects released beta-hydroxybutyrate across the forearm. Acetoacetate was preferentially extracted over beta-hydroxybutyrate. At 24 days of starvation, free fatty acids were the principal fuels extracted by forearm muscle; at this time there was a decreased glucose and also ketone-body consumption by skeletal muscle.

Structure-Function Analysis of the Drosophila melanogaster Caudal Transcription Factor Provides Insights into Core Promoter-preferential Activation.

PubMed

Shir-Shapira, Hila; Sharabany, Julia; Filderman, Matan; Ideses, Diana; Ovadia-Shochat, Avital; Mannervik, Mattias; Juven-Gershon, Tamar

2015-07-10

Regulation of RNA polymerase II transcription is critical for the proper development, differentiation, and growth of an organism. The RNA polymerase II core promoter is the ultimate target of a multitude of transcription factors that control transcription initiation. Core promoters encompass the RNA start site and consist of functional elements such as the TATA box, initiator, and downstream core promoter element (DPE), which confer specific properties to the core promoter. We have previously discovered that Drosophila Caudal, which is a master regulator of genes involved in development and differentiation, is a DPE-specific transcriptional activator. Here, we show that the mouse Caudal-related homeobox (Cdx) proteins (mCdx1, mCdx2, and mCdx4) are also preferential core promoter transcriptional activators. To elucidate the mechanism that enables Caudal to preferentially activate DPE transcription, we performed structure-function analysis. Using a systematic series of deletion mutants (all containing the intact DNA-binding homeodomain) we discovered that the C-terminal region of Caudal contributes to the preferential activation of the fushi tarazu (ftz) Caudal target gene. Furthermore, the region containing both the homeodomain and the C terminus of Caudal was sufficient to confer core promoter-preferential activation to the heterologous GAL4 DNA-binding domain. Importantly, we discovered that Drosophila CREB-binding protein (dCBP) is a co-activator for Caudal-regulated activation of ftz. Strikingly, dCBP conferred the ability to preferentially activate the DPE-dependent ftz reporter to mini-Caudal proteins that were unable to preferentially activate ftz transcription themselves. Taken together, it is the unique combination of dCBP and Caudal that enables the co-activation of ftz in a core promoter-preferential manner. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Plasmid-encoded biosynthetic genes alleviate metabolic disadvantages while increasing glucose conversion to shikimate in an engineered Escherichia coli strain.

PubMed

Rodriguez, Alberto; Martínez, Juan A; Millard, Pierre; Gosset, Guillermo; Portais, Jean-Charles; Létisse, Fabien; Bolivar, Francisco

2017-06-01

Metabolic engineering strategies applied over the last two decades to produce shikimate (SA) in Escherichia coli have resulted in a battery of strains bearing many expression systems. However, the effects that these systems have on the host physiology and how they impact the production of SA are still not well understood. In this work we utilized an engineered E. coli strain to determine the consequences of carrying a vector that promotes SA production from glucose with a high-yield but that is also expected to impose a significant cellular burden. Kinetic comparisons in fermentors showed that instead of exerting a negative effect, the sole presence of the plasmid increased glucose consumption without diminishing the growth rate. By constitutively expressing a biosynthetic operon from this vector, the more active glycolytic metabolism was exploited to redirect intermediates toward the production of SA, which further increased the glucose consumption rate and avoided excess acetate production. Fluxomics and metabolomics experiments revealed a global remodeling of the carbon and energy metabolism in the production strain, where the increased SA production reduced the carbon available for oxidative and fermentative pathways. Moreover, the results showed that the production of SA relies on a specific setup of the pentose phosphate pathway, where both its oxidative and non-oxidative branches are strongly activated to supply erythrose-4-phosphate and balance the NADPH requirements. This work improves our understanding of the metabolic reorganization observed in E. coli in response to the plasmid-based expression of the SA biosynthetic pathway. Biotechnol. Bioeng. 2017;114: 1319-1330. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Twinning and martensite in a 304 austenitic stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Yongfeng; Li, Xi; Sun, Xin

2012-08-30

The microstructure characteristics and deformation behavior of 304L stainless steel during tensile deformation at two different strain rates have been investigated by means of interrupted tensile tests, electron-backscatter-diffraction (EBSD) and transmission electron microscopy (TEM) techniques. The volume fractions of transformed martensite and deformation twins at different stages of the deformation process were measured using X-ray diffraction method and TEM observations. It is found that the volume fraction of martensite monotonically increases with increasing strain but decreases with increasing strain rate. On the other hand, the volume fraction of twins increases with increasing strain for strain level less than 57%. Beyondmore » that, the volume fraction of twins decreases with increasing strain. Careful TEM observations show that stacking faults (SFs) and twins preferentially occur before the nucleation of martensite. Meanwhile, both {var_epsilon}-martensite and {alpha}{prime}-martensite are observed in the deformation microstructures, indicating the co-existence of stress induced- transformation and strain-induced-transformation. We also discussed the effects of twinning and martensite transformation on work-hardening as well as the relationship between stacking faults, twinning and martensite transformation.« less

Anisotropic Nanomechanics of Boron Nitride Nanotubes: Nanostructured "Skin" Effect

NASA Technical Reports Server (NTRS)

Srivastava, Deepak; Menon, Madhu; Cho, KyeongJae

2000-01-01

The stiffness and plasticity of boron nitride nanotubes are investigated using generalized tight-binding molecular dynamics and ab-initio total energy methods. Due to boron-nitride BN bond buckling effects, compressed zigzag BN nanotubes are found to undergo novel anisotropic strain release followed by anisotropic plastic buckling. The strain is preferentially released towards N atoms in the rotated BN bonds. The tubes buckle anisotropically towards only one end when uniaxially compressed from both. A "skin-effect" model of smart nanocomposite materials is proposed which will localize the structural damage towards the 'skin' or surface side of the material.

Production of High-Viscosity Whey Broths by a Lactose-Utilizing Xanthomonas campestris Strain

PubMed Central

Schwartz, Robert D.; Bodie, Elizabeth A.

1985-01-01

Xanthomonas campestris BB-1L was isolated by enrichment and selection by serial passage in a lactose-minimal medium. When BB-1L was subsequently grown in medium containing only 4% whey and 0.05% yeast extract, the lactose was consumed and broth viscosities greater than 500 cps at a 12 s−1 shear rate were produced. Prolonged maintenance in whey resulted in the loss of the ability of BB-1L to produce viscous broths in whey, indicating a reversion to preferential growth on whey protein, like the parent strain. PMID:16346946

Quantification of alcohol drinking patterns in mice.

PubMed

Eisenhardt, Manuela; Leixner, Sarah; Spanagel, Rainer; Bilbao, Ainhoa

2015-11-01

The use of mice in alcohol research provides an excellent model system for a better understanding of the genetics and neurobiology of alcohol addiction. Almost 60 years ago, alcohol researchers began to test strains of mice for alcohol preference and intake. In particular, various voluntary alcohol drinking paradigms in the home cage were developed. In mouse models of voluntary oral alcohol consumption, animals have concurrent access to water and either one or several concentrated alcohol solutions in their home cages. Although these models have high face validity, many experimental conditions require a more precise monitoring of alcohol consumption in mice in order to capture the role of specific strains or genes, or any other manipulation on alcohol drinking behavior. Therefore, we have developed a fully automated, highly precise monitoring system for alcohol drinking in mice in the home cage. This system is now commercially available. We show that this drinkometer system allows for detecting differences in drinking behavior (i) in transgenic mice, (ii) following alcohol deprivation, and (iii) following stress applications that are usually not detected by classical home-cage drinking paradigms. In conclusion, our drinkometer system allows disturbance-free and high resolution monitoring of alcohol drinking behavior. In particular, micro-drinking and circadian drinking patterns can be monitored in genetically modified and inbred strains of mice after environmental and pharmacological manipulation, and therefore this system represents an improvement in measuring behavioral features that are of relevance for the development of alcohol use disorders. © 2015 Society for the Study of Addiction.

Manipulation of GABA in the ventral pallidum, but not the nucleus accumbens, induces intense, preferential, fat consumption in rats.

PubMed

Covelo, Ignacio R; Patel, Zaid I; Luviano, Jennifer A; Stratford, Thomas R; Wirtshafter, David

2014-08-15

Injections of the GABAA antagonist bicuculline into the medial ventral pallidum (VPm) induce marked increases in food intake, but nothing is known about the way in which these injections alter the distribution of intake in a macronutrient selection situation. We investigated this topic by adapting rats to a diet containing independent sources of protein, carbohydrate and fat, and then examining the effects of intra-VPm bicuculline on diet selection. Under these conditions, bicuculline produced a massive, preferential increase in fat intake with subjects consuming a mean of 97% of their calories from fat. Furthermore, all treated subjects ate fat before any other macronutrient, suggesting that the animals' behavior was directed selectively toward this dietary component even before consumption had begun. Similar effects were not observed following food deprivation, which exerted its largest effect on carbohydrate intake. To compare the intra-VPm bicuculline response to that seen after activation of GABA receptors in the nucleus accumbens shell (AcbSh), a major source of projections to the VPm, we conducted similar experiments with intra-AcbSh injections of muscimol and baclofen. These injections also enhanced food intake, but did not reproduce the selective preference for fat seen after intra-VPm bicuculline. These experiments provide the first demonstration of preferential enhancement of fat intake following manipulations of a nonpeptide neurotransmitter. Since mean intakes of fat under baseline conditions and after deprivation tended to be lower than those of carbohydrates, it seems unlikely that the effects of intra-VPm bicuculline are related to the intrinsic "rewarding" properties of fat, but might rather reflect the induction of a state of "fat craving." Copyright © 2014 Elsevier B.V. All rights reserved.

Use of colony-based bacterial strain typing for tracking the fate of Lactobacillus strains during human consumption

PubMed Central

2009-01-01

Background The Lactic Acid Bacteria (LAB) are important components of the healthy gut flora and have been used extensively as probiotics. Understanding the cultivable diversity of LAB before and after probiotic administration, and being able to track the fate of administered probiotic isolates during feeding are important parameters to consider in the design of clinical trials to assess probiotic efficacy. Several methods may be used to identify bacteria at the strain level, however, PCR-based methods such as Random Amplified Polymorphic DNA (RAPD) are particularly suited to rapid analysis. We examined the cultivable diversity of LAB in the human gut before and after feeding with two Lactobacillus strains, and also tracked the fate of these two administered strains using a RAPD technique. Results A RAPD typing scheme was developed to genetically type LAB isolates from a wide range of species, and optimised for direct application to bacterial colony growth. A high-throughput strategy for fingerprinting the cultivable diversity of human faeces was developed and used to determine: (i) the initial cultivable LAB strain diversity in the human gut, and (ii) the fate of two Lactobacillus strains (Lactobacillus salivarius NCIMB 30211 and Lactobacillus acidophilus NCIMB 30156) contained within a capsule that was administered in a small-scale human feeding study. The L. salivarius strain was not cultivated from the faeces of any of the 12 volunteers prior to capsule administration, but appeared post-feeding in four. Strains matching the L. acidophilus NCIMB 30156 feeding strain were found in the faeces of three volunteers prior to consumption; after taking the Lactobacillus capsule, 10 of the 12 volunteers were culture positive for this strain. The appearance of both Lactobacillus strains during capsule consumption was statistically significant (p < 0.05). Conclusion We have shown that genetic strain typing of the cultivable human gut microbiota can be evaluated using a high throughput RAPD technique based on single bacterial colonies. Validation of this strategy paves the way for future systematic studies on the fate and efficacy of bacterial probiotics during human clinical trials. PMID:19968877

Sampling silica and ferrihydrite colloids with fiberglass wicks under unsaturated conditions.

PubMed

Shira, Jason M; Williams, Barbara C; Flury, Markus; Czigány, Szabolcs; Tuller, Markus

2006-01-01

The suitability of passive capillary samplers (PCAPS) for collection of representative colloid samples under partially saturated conditions was evaluated by investigating the transport of negatively and positively charged colloids in fiberglass wicks. A synthetic pore water solution was used to suspend silica microspheres (330 nm in diameter) and ferrihydrite (172 nm in diameter) for transport experiments on fiberglass wicks. Breakthrough curves were collected for three unsaturated flow rates with silica microspheres and one unsaturated flow rate with ferrihydrite colloids. A moisture characteristic curve, relating tensiometer measurements of matric potential to moisture content, was developed for the fiberglass wick. Results indicate that retention of the silica and the ferrihydrite on the wick occurred; that is, the wicks did not facilitate quantitative sampling of the colloids. For silica microspheres, 90% of the colloids were transmitted through the wicks. For ferrihydrite, 80 to 90% of the colloids were transmitted. The mechanisms responsible for the retention of the colloids on the fiberglass wicks appeared to be physicochemical attachment and not thin-film, triple-phase entrapment, or mechanical straining. Visualization of pathways by iron staining indicates that flow is preferential at the center of twisted bundles of filaments. Although axial preferential flow in PCAPS may enhance their hydraulic suitability for sampling mobile colloids, we conclude that without specific preparation to reduce attachment or retention, fiberglass wicks should only be used for qualitative sampling of pore water colloids.

A new approach for selection of Oenococcus oeni strains in order to produce malolactic starters.

PubMed

Coucheney, Françoise; Desroche, Nicolas; Bou, Magali; Tourdot-Maréchal, Raphaëlle; Dulau, Laurent; Guzzo, Jean

2005-12-15

The lactic acid bacterium Oenococcus oeni, mainly responsible for malolactic fermentation (MLF), is used in new winery process as starter culture for direct inoculation. The difficulty to master MLF according to the wine led us to search a new approach to select effective O. oeni strains. Biochemical and molecular tests were performed in order to characterize three strains of O. oeni selected for malolactic starter elaboration. Malolactic and ATPase activities that appeared as a great interest in MLF were measured and the expression of a small heat shock protein Lo18 was evaluated by immunoblotting and real-time PCR. These results were correlated with the performances of strains in two red wines. Physiological and molecular characteristics of the three strains showed significant differences for the global malolactic activity on intact cell at pH 3.0 and at the level of induction of the small heat shock protein Lo18. These two parameters appeared of interest to evaluate in the ability of O. oeni strains to survive into wine after direct inoculation and to perform MLF. Indeed, a tested strain that presented the highest malolactic activity on intact cells at pH 3.0 and a high level of Lo18 induction showed a high growth rate and a high specific kinetic of malate consumption. The techniques used in this work carry out more quickly and more reliable than usual for the selection of effective strains intended for direct inoculation in wines.

Cafestol Inhibits Cyclic-Strain-Induced Interleukin-8, Intercellular Adhesion Molecule-1, and Monocyte Chemoattractant Protein-1 Production in Vascular Endothelial Cells

PubMed Central

Hao, Wen-Rui; Sung, Li-Chin; Chen, Chun-Chao; Chen, Jin-Jer

2018-01-01

Moderate coffee consumption is inversely associated with cardiovascular disease mortality; however, mechanisms underlying this causal effect remain unclear. Cafestol, a diterpene found in coffee, has various properties, including an anti-inflammatory property. This study investigated the effect of cafestol on cyclic-strain-induced inflammatory molecule secretion in vascular endothelial cells. Cells were cultured under static or cyclic strain conditions, and the secretion of inflammatory molecules was determined using enzyme-linked immunosorbent assay. The effects of cafestol on mitogen-activated protein kinases (MAPK), heme oxygenase-1 (HO-1), and sirtuin 1 (Sirt1) signaling pathways were examined using Western blotting and specific inhibitors. Cafestol attenuated cyclic-strain-stimulated intercellular adhesion molecule-1 (ICAM-1), monocyte chemoattractant protein- (MCP-) 1, and interleukin- (IL-) 8 secretion. Cafestol inhibited the cyclic-strain-induced phosphorylation of extracellular signal-regulated kinase and p38 MAPK. By contrast, cafestol upregulated cyclic-strain-induced HO-1 and Sirt1 expression. The addition of zinc protoporphyrin IX, sirtinol, or Sirt1 silencing (transfected with Sirt1 siRNA) significantly attenuated cafestol-mediated modulatory effects on cyclic-strain-stimulated ICAM-1, MCP-1, and IL-8 secretion. This is the first study to report that cafestol inhibited cyclic-strain-induced inflammatory molecule secretion, possibly through the activation of HO-1 and Sirt1 in endothelial cells. The results provide valuable insights into molecular pathways that may contribute to the effects of cafestol. PMID:29854096

Selection against BALB/c strain cells in mouse chimaeras

PubMed Central

Tang, Pin-Chi; MacKay, Gillian E.; Flockhart, Jean H.; Keighren, Margaret A.; Kopakaki, Anna

2018-01-01

ABSTRACT It has been shown previously that BALB/c strain embryos tend to contribute poorly to mouse aggregation chimaeras. In the present study we showed that BALB/c cells were not preferentially allocated to any extraembryonic lineages of mouse aggregation chimaeras, but their contribution decreased during the early postimplantation period and they were significantly depleted by E8.5. The development of BALB/c strain preimplantation embryos lagged behind embryos from some other strains and the contribution that BALB/c and other embryos made to chimaeras correlated with their developmental stage at E2.5. This relationship suggests that the poor contribution of BALB/c embryos to aggregation chimaeras is at least partly a consequence of generalised selection related to slow or delayed preimplantation development. The suitability of BALB/c embryos for maximising the ES cell contribution to mouse ES cell chimaeras is also discussed. PMID:29330350

Monascus ruber as cell factory for lactic acid production at low pH.

PubMed

Weusthuis, Ruud A; Mars, Astrid E; Springer, Jan; Wolbert, Emil Jh; van der Wal, Hetty; de Vrije, Truus G; Levisson, Mark; Leprince, Audrey; Houweling-Tan, G Bwee; Pha Moers, Antoine; Hendriks, Sjon Na; Mendes, Odette; Griekspoor, Yvonne; Werten, Marc Wt; Schaap, Peter J; van der Oost, John; Eggink, Gerrit

2017-07-01

A Monascus ruber strain was isolated that was able to grow on mineral medium at high sugar concentrations and 175g/l lactic acid at pH 2.8. Its genome and transcriptomes were sequenced and annotated. Genes encoding lactate dehydrogenase (LDH) were introduced to accomplish lactic acid production and two genes encoding pyruvate decarboxylase (PDC) were knocked out to subdue ethanol formation. The strain preferred lactic acid to glucose as carbon source, which hampered glucose consumption and therefore also lactic acid production. Lactic acid consumption was stopped by knocking out 4 cytochrome-dependent LDH (CLDH) genes, and evolutionary engineering was used to increase the glucose consumption rate. Application of this strain in a fed-batch fermentation resulted in a maximum lactic acid titer of 190g/l at pH 3.8 and 129g/l at pH 2.8, respectively 1.7 and 2.2 times higher than reported in literature before. Yield and productivity were on par with the best strains described in literature for lactic acid production at low pH. Copyright © 2017 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

Hybrid diffuse optical techniques for continuous hemodynamic measurement in gastrocnemius during plantar flexion exercise

NASA Astrophysics Data System (ADS)

Henry, Brad; Zhao, Mingjun; Shang, Yu; Uhl, Timothy; Thomas, D. Travis; Xenos, Eleftherios S.; Saha, Sibu P.; Yu, Guoqiang

2015-12-01

Occlusion calibrations and gating techniques have been recently applied by our laboratory for continuous and absolute diffuse optical measurements of forearm muscle hemodynamics during handgrip exercises. The translation of these techniques from the forearm to the lower limb is the goal of this study as various diseases preferentially affect muscles in the lower extremity. This study adapted a hybrid near-infrared spectroscopy and diffuse correlation spectroscopy system with a gating algorithm to continuously quantify hemodynamic responses of medial gastrocnemius during plantar flexion exercises in 10 healthy subjects. The outcomes from optical measurement include oxy-, deoxy-, and total hemoglobin concentrations, blood oxygen saturation, and relative changes in blood flow (rBF) and oxygen consumption rate (rV˙O2). We calibrated rBF and rV˙O2 profiles with absolute baseline values of BF and V˙O2 obtained by venous and arterial occlusions, respectively. Results from this investigation were comparable to values from similar studies. Additionally, significant correlation was observed between resting local muscle BF measured by the optical technique and whole limb BF measured concurrently by a strain gauge venous plethysmography. The extensive hemodynamic and metabolic profiles during exercise will allow for future comparison studies to investigate the diagnostic value of hybrid technologies in muscles affected by disease.

Preliminary study on the antimicrobial susceptibility pattern related to the genotype of Vibrio vulnificus strains isolated in the north-western Adriatic Sea coastal area.

PubMed

Serratore, Patrizia; Zavatta, Emanuele; Fiocchi, Eleonora; Serafini, Emanuele; Serraino, Andrea; Giacometti, Federica; Bignami, Giorgia

2017-10-20

V. vulnificus is a Gram-negative bacterium, commonly found in estuarine and coastal habitats, that can infect humans through seafood consumption or wound exposure. This study represents the first attempt to correlate the genotype of Vibrio vulnificus strains isolated in the north-western Adriatic Sea coastal area, with their antimicrobial susceptibility patterns. On the whole, 40 V. vulnificus strains, isolated from shellfish (n=20), different coastal water bodies (n=19), and the blood of a Carretta carretta turtle (n=1), were utilized. All strains were positive for the species-specific genes vvh A and hsp , with high variability for other markers: 55% (22 out of 40) resulted of the environmental (E) genotype ( vcg E, 16S rRNA type A, CPS2 or CPS0), 10% (4 out of 40) of the clinical (C) genotype ( vcg C, 16S rRNA type B, CPS1), and 35% (14 out of 40) of the mixed (M) genotype, possessing both E and C markers. The antimicrobial susceptibility was assayed by the diffusion method on agar, according to the Clinical Laboratory Standards Institute (CLSI), utilizing the following commercial disks (Oxoid): ampicillin (AMP), ampicillin- sulbactam (SAM), piperacillin (PRL), cefazolin (KZ), cefotaxime(CTX), ceftazidime (CAZ), imipenem (IPM), meropenem (MEM), amikacin (AK), gentamicin(CN), tetracycline(TE), ciprofloxacin (CIP), levofloxacin (LEV), trimethoprim-sulfamethoxazole (SXT), and chloramphenicol (C). 75% of the strains, (n=30) including all C strains, was sensitive to all the tested antibiotics, whereas E strains showed intermediate sensitivity to AK (2 strains), CIP and CAZ (1 strain), TE (1 strain) and resistance to KZ (1 strain), and 4 M strains showed I to AK.

Macroscopic inhomogeneous deformation behavior arising in single crystal Ni-Mn-Ga foils under tensile loading

NASA Astrophysics Data System (ADS)

Murasawa, Go; Yeduru, Srinivasa R.; Kohl, Manfred

2016-12-01

This study investigated macroscopic inhomogeneous deformation occurring in single-crystal Ni-Mn-Ga foils under uniaxial tensile loading. Two types of single-crystal Ni-Mn-Ga foil samples were examined as-received and after thermo-mechanical training. Local strain and the strain field were measured under tensile loading using laser speckle and digital image correlation. The as-received sample showed a strongly inhomogeneous strain field with intermittence under progressive deformation, but the trained sample result showed strain field homogeneity throughout the specimen surface. The as-received sample is a mainly polycrystalline-like state composed of the domain structure. The sample contains many domain boundaries and large domain structures in the body. Its structure would cause large local strain band nucleation with intermittence. However, the trained one is an ideal single-crystalline state with a transformation preferential orientation of variants after almost all domain boundary and large domain structures vanish during thermo-mechanical training. As a result, macroscopic homogeneous deformation occurs on the trained sample surface during deformation.

Mechanism of Citrate Metabolism by an Oxaloacetate Decarboxylase-Deficient Mutant of Lactococcus lactis IL1403 ▿

PubMed Central

Pudlik, Agata M.; Lolkema, Juke S.

2011-01-01

Citrate metabolism in resting cells of Lactococcus lactis IL1403(pFL3) results in the formation of two end products from the intermediate pyruvate, acetoin and acetate (A. M. Pudlik and J. S. Lolkema, J. Bacteriol. 193:706–714, 2011). Pyruvate is formed from citrate following uptake by the transporter CitP through the subsequent actions of citrate lyase and oxaloacetate decarboxylase. The present study describes the metabolic response of L. lactis when oxaloacetate accumulates in the cytoplasm. The oxaloacetate decarboxylase-deficient mutant ILCitM(pFL3) showed nearly identical rates of citrate consumption, but the end product profile in the presence of glucose shifted from mainly acetoin to only acetate. In addition, in contrast to the parental strain, the mutant strain did not generate proton motive force. Citrate consumption by the mutant strain was coupled to the excretion of oxaloacetate, with a yield of 80 to 85%. Following citrate consumption, oxaloacetate was slowly taken up by the cells and converted to pyruvate by a cryptic decarboxylase and, subsequently, to acetate. The transport of oxaloacetate is catalyzed by CitP. The parental strain IL1403(pFL3) containing CitP consumed oxaloacetate, while the original strain, IL1403, not containing CitP, did not. Moreover, oxaloacetate consumption was enhanced in the presence of l-lactate, indicating exchange between oxaloacetate and l-lactate catalyzed by CitP. Hence, when oxaloacetate inadvertently accumulates in the cytoplasm, the physiological response of L. lactis is to excrete oxaloacetate in exchange with citrate by an electroneutral mechanism catalyzed by CitP. Subsequently, in a second step, oxaloacetate is taken up by CitP and metabolized to pyruvate and acetate. PMID:21665973

Mechanism of citrate metabolism by an oxaloacetate decarboxylase-deficient mutant of Lactococcus lactis IL1403.

PubMed

Pudlik, Agata M; Lolkema, Juke S

2011-08-01

Citrate metabolism in resting cells of Lactococcus lactis IL1403(pFL3) results in the formation of two end products from the intermediate pyruvate, acetoin and acetate (A. M. Pudlik and J. S. Lolkema, J. Bacteriol. 193:706-714, 2011). Pyruvate is formed from citrate following uptake by the transporter CitP through the subsequent actions of citrate lyase and oxaloacetate decarboxylase. The present study describes the metabolic response of L. lactis when oxaloacetate accumulates in the cytoplasm. The oxaloacetate decarboxylase-deficient mutant ILCitM(pFL3) showed nearly identical rates of citrate consumption, but the end product profile in the presence of glucose shifted from mainly acetoin to only acetate. In addition, in contrast to the parental strain, the mutant strain did not generate proton motive force. Citrate consumption by the mutant strain was coupled to the excretion of oxaloacetate, with a yield of 80 to 85%. Following citrate consumption, oxaloacetate was slowly taken up by the cells and converted to pyruvate by a cryptic decarboxylase and, subsequently, to acetate. The transport of oxaloacetate is catalyzed by CitP. The parental strain IL1403(pFL3) containing CitP consumed oxaloacetate, while the original strain, IL1403, not containing CitP, did not. Moreover, oxaloacetate consumption was enhanced in the presence of L-lactate, indicating exchange between oxaloacetate and L-lactate catalyzed by CitP. Hence, when oxaloacetate inadvertently accumulates in the cytoplasm, the physiological response of L. lactis is to excrete oxaloacetate in exchange with citrate by an electroneutral mechanism catalyzed by CitP. Subsequently, in a second step, oxaloacetate is taken up by CitP and metabolized to pyruvate and acetate.

Diversity of staphylococcal cassette chromosome mec structures in methicillin-resistant Staphylococcus epidermidis and Staphylococcus haemolyticus strains among outpatients from four countries.

PubMed

Ruppé, Etienne; Barbier, François; Mesli, Yasmine; Maiga, Aminata; Cojocaru, Radu; Benkhalfat, Mokhtar; Benchouk, Samia; Hassaine, Hafida; Maiga, Ibrahim; Diallo, Amadou; Koumaré, Abdel Karim; Ouattara, Kalilou; Soumaré, Sambou; Dufourcq, Jean-Baptiste; Nareth, Chhor; Sarthou, Jean-Louis; Andremont, Antoine; Ruimy, Raymond

2009-02-01

In staphylococci, methicillin (meticillin) resistance (MR) is mediated by the acquisition of the mecA gene, which is carried on the size and composition variable staphylococcal cassette chromosome mec (SCCmec). MR has been extensively studied in Staphylococcus aureus, but little is known about MR coagulase-negative staphylococci (MR-CoNS). Here, we describe the diversity of SCCmec structures in MR-CoNS from outpatients living in countries with contrasting environments: Algeria, Mali, Moldova, and Cambodia. Their MR-CoNS nasal carriage rates were 29, 17, 11, and 31%, respectively. Ninety-six MR-CoNS strains, comprising 75 (78%) Staphylococcus epidermidis strains, 19 (20%) Staphylococcus haemolyticus strains, 1 (1%) Staphylococcus hominis strain, and 1 (1%) Staphylococcus cohnii strain, were analyzed. Eighteen different SCCmec types were observed, with 28 identified as type IV (29%), 25 as type V (26%), and 1 as type III (1%). Fifteen strains (44%) were untypeable for their SCCmec. Thirty-four percent of MR-CoNS strains contained multiple ccr copies. Type IV and V SCCmec were preferentially associated with S. epidermidis and S. haemolyticus, respectively. MR-CoNS constitute a widespread and highly diversified MR reservoir in the community.

Actinomyces naeslundii Displays Variant fimP and fimA Fimbrial Subunit Genes Corresponding to Different Types of Acidic Proline-Rich Protein and β-Linked Galactosamine Binding Specificity

PubMed Central

Hallberg, K.; Holm, C.; Öhman, U.; Strömberg, N.

1998-01-01

Actinomyces naeslundii genospecies 1 and 2 bind to acidic proline-rich proteins (APRPs) and statherin via type 1 fimbriae and to β-linked galactosamine (GalNAcβ) structures via type 2 fimbriae. In addition, A. naeslundii displays two types of binding specificity for both APRPs-statherin and GalNAcβ, while Actinomyces odontolyticus binds to unknown structures. To study the molecular basis for these binding specificities, DNA fragments spanning the entire or central portions of fimP (type 1) and fimA (type 2) fimbrial subunit genes were amplified by PCR from strains of genospecies 1 and 2 and hybridized with DNA from two independent collections of oral Actinomyces isolates. Isolates of genospecies 1 and 2 and A. odontolyticus, but no other Actinomyces species, were positive for hybridization with fimP and fimA full-length probes irrespective of binding to APRPs and statherin, GalNAcβ, or unknown structures. Isolates of genospecies 1 and 2, with deviating patterns of GalNAcβ1-3Galα-O-ethyl-inhibitable coaggregation with Streptococcus oralis Ss34 and MPB1, were distinguished by a fimA central probe from genospecies 1 and 2, respectively. Furthermore, isolates of genospecies 1 and 2 displaying preferential binding to APRPs over statherin were positive with a fimP central probe, while a genospecies 2 strain with the opposite binding preference was not. The sequences of fimP and fimA central gene segments were highly conserved among isolates with the same, but diversified between those with a variant, binding specificity. In conclusion, A. naeslundii exhibits variant fimP and fimA genes corresponding to diverse APRP and GalNAcβ specificities, respectively, while A. odontolyticus has a genetically related but distinct adhesin binding specificity. PMID:9712794

Effect of Agave tequilana age, cultivation field location and yeast strain on tequila fermentation process.

PubMed

Pinal, L; Cornejo, E; Arellano, M; Herrera, E; Nuñez, L; Arrizon, J; Gschaedler, A

2009-05-01

The effect of yeast strain, the agave age and the cultivation field location of agave were evaluated using kinetic parameters and volatile compound production in the tequila fermentation process. Fermentations were carried out with Agave juice obtained from two cultivation fields (CF1 and CF2), as well as two ages (4 and 8 years) and two Saccharomyces cerevisiae yeast strains (GU3 and AR5) isolated from tequila fermentation must. Sugar consumption and ethanol production varied as a function of cultivation field and agave age. The production of ethyl acetate, 1-propanol, isobutanol and amyl alcohols were influenced in varying degrees by yeast strain, agave age and cultivation field. Methanol production was only affected by the agave age and 2-phenylethanol was influenced only by yeast strain. This work showed that the use of younger Agave tequilana for tequila fermentation resulted in differences in sugar consumption, ethanol and volatile compounds production at the end of fermentation, which could affect the sensory quality of the final product.

Thermal resistance of Salmonella serovars isolated from raw, frozen chicken nuggets/strips, nugget meat and pelleted broiler feed.

PubMed

Bucher, Oliver; D'Aoust, J-Y; Holley, Richard A

2008-05-31

Raw, frozen chicken nuggets/strips available at retail and prepared at home before consumption have been identified as a significant risk factor in contracting food-borne salmonellosis. Cases of salmonellosis from consumption of these products may be due, in part, to Salmonella strains originating in broiler feed. In this study the thermal resistances of Salmonella strains isolated from chicken nuggets and strips, chicken nugget/strip meat and broiler feed were determined to assess whether they exhibited enhanced thermal resistance. Thermal resistances (D- and z- values) of 7 cocktails (25 isolates, 4 serovars) were determined in commercially prepared irradiation-treated chicken nugget/strip meat blend, and heated in a constant temperature waterbath. The thermal resistances found were lower than those reported for similar strains in the literature. D-values ranged from 6.93 to 0.12 min at 55 and 62 degrees C respectively, with z-values from 4.10 to 5.17 degrees C. Two strains of S. Enteritidis separately isolated from pelleted feed and chicken nugget meat blend, with indistinguishable geno- and phenotypes, had lower (and probably identical) thermal resistances than the other isolates. Results indicated that the strains of Salmonella isolated from raw, frozen chicken nuggets/strips and pelleted broiler feed did not exhibit unusually high thermal resistance, and that normal heating (71 degrees C) prior to consumption should eliminate these organisms from chicken nuggets/strips.

Investigation of Preferential Flow in Low Impact Development Practice

NASA Astrophysics Data System (ADS)

Liu, L.; Cao, R.; Wang, C.; Jiang, W.; Wang, J.; Xia, Z.

2016-12-01

The characteristics of preferential flow in soil affect Low Impact Development (LID) practices in two aspects. On the one hand, preferential flow may facilitate drainage of stormwater by causing non-uniform movement of water through a small portion of media (such as cracks and holes), and thus leading to much faster transport of water and solutes in one specific direction than others. On the other hand, within a certain ranges, preferential flow may weaken the subgrade capacity of pressure and/or shear stress resistance. Therefore, for the purpose of improving LID practices, there may exist an optimum scenario with a high allowable flowrate and least negative impact of resistance capacity for a soil layer. This project aims to assist the LID design by exploring the features of preferential flow in different soil compositions, studying how different flow paths affect the stability of subgrade, preliminarily analyzing the sensitivity of preferential flow impacting on drainage capacity and subgrade stability in the LID, and further optimizing LID practices. Accordingly, the concepts of Essential Direction Path, Unessential Direction Path and the Sensitivity Coefficient are defined and analyzed to simulate a hypothetical funneling scenario in LID practice. Both irrigation apparatus experiments and numerical models are utilized in this research to investigate the features of preferential flow, effective strength and overall shear strength. The main conclusions include: (1) Investigation of preferential flow characteristics in essential direction path and unessential direction path, respectively; (2) Optimum design of preferential flow in LID practice; (3) Transport capacity determination of preferential flow path in different soils; (4) Study of preferential flow impact on roadbed stability. KEY WORDS: Preferential Flow, Subgrade stability, LID, Sensitivity Coefficient, Funneling Preferential Flow Path

Chemical expansion affected oxygen vacancy stability in different oxide structures from first principles calculations

DOE PAGES

Aidhy, Dilpuneet S.; Liu, Bin; Zhang, Yanwen; ...

2015-01-21

We study the chemical expansion for neutral and charged oxygen vacancies in fluorite, rocksalt, perovskite and pyrochlores materials using first principles calculations. We show that the neutral oxygen vacancy leads to lattice expansion whereas the charged vacancy leads to lattice contraction. In addition, we show that there is a window of strain within which an oxygen vacancy is stable; beyond that range, the vacancy can become unstable. Using CeO 2|ZrO 2 interface structure as an example, we show that the concentration of oxygen vacancies can be manipulated via strain, and the vacancies can be preferentially stabilized. Furthermore, these results couldmore » serve as guiding principles in predicting oxygen vacancy stability in strained systems and in the design of vacancy stabilized materials.« less

Recycling Carbon Dioxide during Xylose Fermentation by Engineered Saccharomyces cerevisiae.

PubMed

Xia, Peng-Fei; Zhang, Guo-Chang; Walker, Berkley; Seo, Seung-Oh; Kwak, Suryang; Liu, Jing-Jing; Kim, Heejin; Ort, Donald R; Wang, Shu-Guang; Jin, Yong-Su

2017-02-17

Global climate change caused by the emission of anthropogenic greenhouse gases (GHGs) is a grand challenge to humanity. To alleviate the trend, the consumption of fossil fuels needs to be largely reduced and alternative energy technologies capable of controlling GHG emissions are anticipated. In this study, we introduced a synthetic reductive pentose phosphate pathway (rPPP) into a xylose-fermenting Saccharomyces cerevisiae strain SR8 to achieve simultaneous lignocellulosic bioethanol production and carbon dioxide recycling. Specifically, ribulose-1,5-bisphosphate carboxylase/oxygenase from Rhodospirillum rubrum and phosphoribulokinase from Spinacia oleracea were introduced into the SR8 strain. The resulting strain with the synthetic rPPP was able to exhibit a higher yield of ethanol and lower yields of byproducts (xylitol and glycerol) than a control strain. In addition, the reduced release of carbon dioxide by the engineered strain was observed during xylose fermentation, suggesting that the carbon dioxide generated by pyruvate decarboxylase was partially reassimilated through the synthetic rPPP. These results demonstrated that recycling of carbon dioxide from the ethanol fermentation pathway in yeast can be achieved during lignocellulosic bioethanol production through a synthetic carbon conservative metabolic pathway. This strategy has a great potential to alleviate GHG emissions during the production of second-generation ethanol.

The First Report of Vibrio parahaemolyticus Strain O10:K60 in Japan, a New Combination of O and K Serotypes Isolated from a Patient with Gastroenteritis.

PubMed

Ueno, Hiroyuki; Tomari, Kentaro; Kikuchi, Koji; Kobori, Sumie; Miyazaki, Motonobu

2016-01-01

Vibrio parahaemolyticus is an important pathogen that causes gastroenteritis in humans, generally associated with the consumption of contaminated seafood, particularly raw shellfish. There are many serotypes in V. parahaemolyticus resulting from a combination of O and K antigens. Among them, O3:K6 and their variants, which represent the pandemic clone, are the most widespread strains worldwide. In this study, we examined V. parahaemolyticus isolated from a gastroenteritis patient's stool at a hospital in Saitama City, Japan in 2013. Serotyping of the O and K antigens identified the strain as O10:K60. To our knowledge, this is the first reported case of a V. parahaemolyticus strain with this antigen combination in Japan. Subsequently, we used PCR to assay for pathogenicity-associated genes, and found that it was positive for tdh, T3SS1, and T3SS2α genes. Antibiotic susceptibility tests showed that the strain was susceptible to all selected antibiotics except ampicillin. Moreover, we detected specific marker genes for the pandemic clone with two kinds of PCR assay. Our results suggest that the isolate O10:K60 is a newly emerging serotype that belongs to the pandemic clone.

Enhanced Bioconversion of Cellobiose by Industrial Saccharomyces cerevisiae Used for Cellulose Utilization

PubMed Central

Hu, Meng-Long; Zha, Jian; He, Lin-Wei; Lv, Ya-Jin; Shen, Ming-Hua; Zhong, Cheng; Li, Bing-Zhi; Yuan, Ying-Jin

2016-01-01

Cellobiose accumulation and the compromised temperature for yeast fermentation are the main limiting factors of enzymatic hydrolysis process during simultaneous saccharification and fermentation (SSF). In this study, genes encoding cellobiose transporter and β-glucosidase were introduced into an industrial Saccharomyces cerevisiae strain, and evolution engineering was carried out to improve the cellobiose utilization of the engineered yeast strain. The evolved strain exhibited significantly higher cellobiose consumption rate (2.8-fold) and ethanol productivity (4.9-fold) compared with its parent strain. Besides, the evolved strain showed a high cellobiose consumption rate of 3.67 g/L/h at 34°C and 3.04 g/L/h at 38°C. Moreover, little cellobiose was accumulated during SSF of Avicel using the evolved strain at 38°C, and the ethanol yield from Avicel increased by 23% from 0.34 to 0.42 g ethanol/g cellulose. Overexpression of the genes encoding cellobiose transporter and β-glucosidase accelerated cellobiose utilization, and the improvement depended on the strain background. The results proved that fast cellobiose utilization enhanced ethanol production by reducing cellobiose accumulation during SSF at high temperature. PMID:26973619

Phenotypic and Transcriptomic Responses of Campylobacter jejuni Suspended in an Artificial Freshwater Medium

PubMed Central

Trigui, Hana; Lee, Kristen; Thibodeau, Alexandre; Lévesque, Simon; Mendis, Nilmini; Fravalo, Philippe; Letellier, Ann; Faucher, Sébastien P.

2017-01-01

Campylobacter jejuni is the leading cause of campylobacteriosis in the developed world. Although most cases are caused by consumption of contaminated meat, a significant proportion is linked to ingestion of contaminated water. The differences between C. jejuni strains originating from food products and those isolated from water are poorly understood. Working under the hypothesis that water-borne C. jejuni strains are better equipped at surviving the nutrient-poor aquatic environment than food-borne strains, the present study aims to characterize these differences using outbreak strains 81116 and 81-176. Strain 81116 caused a campylobacteriosis outbreak linked to consumption of water, while strain 81-176 was linked to consumption of raw milk. CFU counts and viability assays showed that 81116 survives better than 81-176 at 4°C in a defined freshwater medium (Fraquil). Moreover, 81116 was significantly more resistant to oxidative stress and bile salt than strain 81-176 in Fraquil. To better understand the genetic response of 81116 to water, a transcriptomic profiling study was undertaken using microarrays. Compared to rich broth, strain 81116 represses genes involved in amino acid uptake and metabolism, as well as genes involved in costly biosynthetic processes such as replication, translation, flagellum synthesis and virulence in response to Fraquil. In accordance with the observed increase in stress resistance in Fraquil, 81116 induces genes involved in resistance to oxidative stress and bile salt. Interestingly, genes responsible for cell wall synthesis were also induced upon Fraquil exposure. Finally, twelve unique genes were expressed in Fraquil; however, analysis of their distribution in animal and water isolates showed that they are not uniquely and ubiquitously present in water isolates, and thus, unlikely to play a major role in adaptation to water. Our results show that some C. jejuni strains are more resilient than others, thereby challenging current water management practices. The response of 81116 to Fraquil serves as a starting point to understand the adaptation of C. jejuni to water and its subsequent transmission. PMID:28979243

Development and application of a multiplex PCR assay for detection of the Clostridium perfringens enterotoxin-encoding genes cpe and becAB.

PubMed

Yonogi, Shinya; Kanki, Masashi; Ohnishi, Takahiro; Shiono, Masami; Iida, Tetsuya; Kumeda, Yuko

2016-08-01

Clostridium perfringens causes food-borne gastroenteritis following the consumption of contaminated food by producing C. perfringens enterotoxin (CPE) in the intestines. Recently, we reported a novel enterotoxin, binary enterotoxin of C. perfringens (BEC) in C. perfringens isolates, which caused two disease outbreaks in Japan. Consequently, in the event of food poisoning outbreaks caused by C. perfringens, it is now necessary to screen for both the cpe and becAB genes by diagnostic PCR. Here, we present a simple multiplex PCR method for simultaneous detection of cpe, becAB and a C. perfringens control locus, phospholipase C (plc). Applying this method, we investigated the prevalence of cpe- or becAB-carrying C. perfringens strains in human stool and bovine rectum swab samples. Using a total of 169 isolates, we found that the percentage of becAB-carrying strains was very small (0.59%), one-tenth that of cpe-carrying strains. The simple method presented in this study with high specificity and sensitivity to C. perfringens will be a useful tool to survey the global prevalence of becAB-carrying C. perfringens strains. Copyright © 2016 Elsevier B.V. All rights reserved.

Intrinsic kinetic parameters of Thermococcus onnurineus NA1 strains and prediction of optimum carbon monoxide level for ideal bioreactor operation.

PubMed

Jeong, Yeseul; Jang, Nulee; Yasin, Muhammad; Park, Shinyoung; Chang, In Seop

2016-02-01

This study determines and compares the intrinsic kinetic parameters (Ks and Ki) of selected Thermococcus onnurineus NA1 strains (wild-type (WT), and mutants MC01, MC02, and WTC156T) using the substrate inhibition model. Ks and Ki values were used to find the optimum dissolved CO (CL) conditions inside the reactor. The results showed that in terms of the maximum specific CO consumption rates (qCO(max)) of WT, MC01, MC02, and WTC156T the optimum activities can be achieved by maintaining the CL levels at 0.56mM, 0.52mM, 0.58mM, and 0.75mM, respectively. The qCO(max) value of WTC156T at 0.75mM was found to be 1.5-fold higher than for the WT strain, confirming its superiority. Kinetic modeling was then used to predict the conditions required to maintain the optimum CL levels and high cell concentrations in the reactor, based on the kinetic parameters of the WTC156T strain. Copyright © 2015 Elsevier Ltd. All rights reserved.

Acetate adaptation of clostridia tyrobutyricum for improved fermentation production of butyrate.

PubMed

Jaros, Adam M; Rova, Ulrika; Berglund, Kris A

2013-12-01

Clostridium tyrobutyricum ATCC 25755 is an acidogenic bacterium capable of utilizing xylose for the fermentation production of butyrate. Hot water extraction of hardwood lingocellulose is an efficient method of producing xylose where autohydrolysis of xylan is catalysed by acetate originating from acetyl groups present in hemicellulose. The presence of acetic acid in the hydrolysate might have a severe impact on the subsequent fermentations. In this study the fermentation kinetics of C. tyrobutyricum cultures after being classically adapted for growth at 26.3 g/L acetate equivalents were studied. Analysis of xylose batch fermentations found that even in the presence of high levels of acetate, acetate adapted strains had similar fermentation kinetics as the parental strain cultivated without acetate. The parental strain exposed to acetate at inhibitory conditions demonstrated a pronounced lag phase (over 100 hours) in growth and butyrate production as compared to the adapted strain (25 hour lag) or non-inhibited controls (0 lag). Additional insight into the metabolic pathway of xylose consumption was gained by determining the specific activity of the acetate kinase (AK) enzyme in adapted versus control batches. AK activity was reduced by 63% in the presence of inhibitory levels of acetate, whether or not the culture had been adapted.

Alcohol drinking during adolescence increases consumptive responses to alcohol in adulthood in Wistar rats

PubMed Central

Amodeo, Leslie R.; Kneiber, Diana; Wills, Derek N.; Ehlers, Cindy L.

2017-01-01

Binge drinking and the onset of alcohol use disorders usually peak during the transition between late adolescence and early adulthood, and early adolescent onset of alcohol consumption has been demonstrated to increase the risk for alcohol dependence in adulthood. In the present study we describe an animal model of early adolescent alcohol consumption where animals drink unsweetened and unflavored ethanol in high concentrations (20%). Using this model we investigated the influence of drinking on alcohol-related appetitive behavior and alcohol consumption levels in early adulthood. Further, we also sought to investigate whether differences in alcohol-related drinking behaviors were specific to exposure in adolescence versus exposure in adulthood. Male Wistar rats were given a 2-bottle choice between 20% ethanol and water in one group and between two water bottles in another group during their adolescence (Postnatal Day (PD) PD26-59) to model voluntary drinking in adolescent humans. As young adults (PD85), rats were trained in a paradigm that provided free access to 20% alcohol for 25 min after completing up to a fixed ratio (FR) 16-lever press response. A set of young adult male Wistar rats was exposed to the same paradigm using the same time course beginning at PD92. The results indicate that adolescent exposure to alcohol increased consumption of alcohol in adulthood. Furthermore, when investigating differences between adolescent high and low adolescent drinkers in adulthood, high consumers continued to drink more alcohol, had fewer FR failures, and had faster completion of FR schedules in adulthood whereas the low consumers were no different than controls. Rats exposed to ethanol in young adulthood also increased future intake but there were no differences in any other components of drinking behavior. Both adolescent- and adult-exposed rats did not exhibit an increase in lever pressing during the appetitive challenge session. These data indicate that adolescent and early adult alcohol exposure can increase consumptive aspects of drinking but that adolescent exposure may preferentially influence the motivation to drink. PMID:28187948

Effect of acetic acid and pH on the cofermentation of glucose and xylose to ethanol by a genetically engineered strain of Saccharomyces cerevisiae.

PubMed

Casey, Elizabeth; Sedlak, Miroslav; Ho, Nancy W Y; Mosier, Nathan S

2010-06-01

A current challenge of the cellulosic ethanol industry is the effect of inhibitors present in biomass hydrolysates. Acetic acid is an example of one such inhibitor that is released during the pretreatment of hemicellulose. This study examined the effect of acetic acid on the cofermentation of glucose and xylose under controlled pH conditions by Saccharomyces cerevisiae 424A(LNH-ST), a genetically engineered industrial yeast strain. Acetic acid concentrations of 7.5 and 15 g L(-1), representing the range of concentrations expected in actual biomass hydrolysates, were tested under controlled pH conditions of 5, 5.5, and 6. The presence of acetic acid in the fermentation media led to a significant decrease in the observed maximum cell biomass concentration. Glucose- and xylose-specific consumption rates decreased as the acetic acid concentration increased, with the inhibitory effect being more severe for xylose consumption. The ethanol production rates also decreased when acetic acid was present, but ethanol metabolic yields increased under the same conditions. The results also revealed that the inhibitory effect of acetic acid could be reduced by increasing media pH, thus confirming that the undissociated form of acetic acid is the inhibitory form of the molecule.

Flame-vortex interactions imaged in microgravity

NASA Technical Reports Server (NTRS)

Driscoll, James F.; Dahm, Werner J. A.; Sichel, Martin

1995-01-01

The scientific objective is to obtain high quality color-enhanced digital images of a vortex exerting aerodynamic strain on premixed and nonpremixed flames with the complicating effects of buoyancy removed. The images will provide universal (buoyancy free) scaling relations that are required to improve several types of models of turbulent combustion, including KIVA-3, discrete vortex, and large-eddy simulations. The images will be used to help quantify several source terms in the models, including those due to flame stretch, flame-generated vorticity, flame curvature, and preferential diffusion, for a range of vortex sizes and flame conditions. The experiment is an ideal way to study turbulence-chemistry interactions and isolate the effect of vortices of different sizes and strengths in a repeatable manner. A parallel computational effort is being conducted which considers full chemistry and preferential diffusion.

Discrete Analysis of Damage and Shear Banding in Argillaceous Rocks

NASA Astrophysics Data System (ADS)

Dinç, Özge; Scholtès, Luc

2018-05-01

A discrete approach is proposed to study damage and failure processes taking place in argillaceous rocks which present a transversely isotropic behavior. More precisely, a dedicated discrete element method is utilized to provide a micromechanical description of the mechanisms involved. The purpose of the study is twofold: (1) presenting a three-dimensional discrete element model able to simulate the anisotropic macro-mechanical behavior of the Callovo-Oxfordian claystone as a particular case of argillaceous rocks; (2) studying how progressive failure develops in such material. Material anisotropy is explicitly taken into account in the numerical model through the introduction of weakness planes distributed at the interparticle scale following predefined orientation and intensity. Simulations of compression tests under plane-strain and triaxial conditions are performed to clarify the development of damage and the appearance of shear bands through micromechanical analyses. The overall mechanical behavior and shear banding patterns predicted by the numerical model are in good agreement with respect to experimental observations. Both tensile and shear microcracks emerging from the modeling also present characteristics compatible with microstructural observations. The numerical results confirm that the global failure of argillaceous rocks is well correlated with the mechanisms taking place at the local scale. Specifically, strain localization is shown to directly result from shear microcracking developing with a preferential orientation distribution related to the orientation of the shear band. In addition, localization events presenting characteristics similar to shear bands are observed from the early stages of the loading and might thus be considered as precursors of strain localization.

Strain rate dependent calcite microfabric evolution - An experiment carried out by nature

NASA Astrophysics Data System (ADS)

Rogowitz, Anna; Grasemann, Bernhard; Huet, Benjamin; Habler, Gerlinde

2014-12-01

A flanking structure developed along a secondary shear zone in calcite marbles, on Syros (Cyclades, Greece), provides a natural laboratory for directly studying the effects of strain rate variations on calcite deformation at identical pressure and temperature conditions. The presence and rotation of a fracture during progressive deformation caused extreme variations in finite strain and strain rate, forming a localized ductile shear zone that shows different microstructures and textures. Textures and the degree of intracrystalline deformation were measured by electron backscattered diffraction. Marbles from the host rocks and the shear zone, which deformed at various strain rates, display crystal-preferred orientation, suggesting that the calcite preferentially deformed by intracrystalline-plastic deformation. Increasing strain rate results in a switch from subgrain rotation to bulging recrystallization in the dislocation-creep regime. With increasing strain rate, we observe in fine-grained (3 μm) ultramylonitic zones a change in deformation regime from grain-size insensitive to grain-size sensitive. Paleowattmeter and the paleopiezometer suggest strain rates for the localized shear zone around 10-10 s-1 and for the marble host rock around 10-12 s-1. We conclude that varying natural strain rates can have a first-order effect on the microstructures and textures that developed under the same metamorphic conditions.

When and where does preferential flow matter - from observation to large scale modelling

NASA Astrophysics Data System (ADS)

Weiler, Markus; Leistert, Hannes; Steinbrich, Andreas

2017-04-01

Preferential flow can be of relevance in a wide range of soils and the interaction of different processes and factors are still difficult to assess. As most studies (including our own studies) focusing on the effect of preferential flow are based on relatively high precipitation rates, there is always the question how relevant preferential flow is under natural conditions, considering the site specific precipitation characteristics, the effect of the drying and wetting cycle on the initial soil water condition and shrinkage cracks, the site specific soil properties, soil structure and rock fragments, and the effect of plant roots and soil fauna (e.g. earthworm channels). In order to assess this question, we developed the distributed, process-based model RoGeR (Runoff Generation Research) to include a large number relevant features and processes of preferential flow in soils. The model was developed from a large number of process based research and experiments and includes preferential flow in roots, earthworm channels, along rock fragments and shrinkage cracks. We parameterized the uncalibrated model at a high spatial resolution of 5x5m for the whole state of Baden-Württemberg in Germany using LiDAR data, degree of sealing, landuse, soil properties and geology. As the model is an event based model, we derived typical event based precipitation characteristics based on rainfall duration, mean intensity and amount. Using the site-specific variability of initial soil moisture derived from a water balance model based on the same dataset, we simulated the infiltration and recharge amounts of all event classes derived from the event precipitation characteristics and initial soil moisture conditions. The analysis of the simulation results allowed us to extracts the relevance of preferential flow for infiltration and recharge considering all factors above. We could clearly see a strong effect of the soil properties and land-use, but also, particular for clay rich soils a strong effect of the initial conditions due to the development of soil cracks. Not too surprisingly, the relevance of preferential flow was much lower when considering the whole range of precipitation events as only considering events with a high rainfall intensity. Also, the influence on infiltration and recharge were different. Despite the model can still be improved in particular considering more realistic information about the spatial and temporal variability of preferential flow by soil fauna and plants, the model already shows under what situation we need to be very careful when predicting infiltration and recharge with models considering only longer time steps (daily) or only matrix flow.

Biofilm density and detection of biofilm-producing genes in methicillin-resistant Staphylococcus aureus strains.

PubMed

Szczuka, Ewa; Urbańska, Katarzyna; Pietryka, Marta; Kaznowski, Adam

2013-01-01

Many serious diseases caused by Staphylococcus aureus appear to be associated with biofilms. Therefore, we investigated the biofilm-forming ability of the methicillin-resistant S. aureus (MRSA) isolates collected from hospitalized patients. As many as 96 % strains had the ability to form biofilm in vitro. The majority of S. aureus strains formed biofilm in ica-dependent mechanism. However, 23 % of MRSA isolates formed biofilm in ica-independent mechanism. Half of these strains carried fnbB genes encoding surface proteins fibronectin-binding protein B involved in intercellular accumulation and biofilm development in S. aureus strains. The biofilm structures were examined via confocal laser scanning microscopy (CLSM) and three-dimensional structures were reconstructed. The images obtained in CLSM revealed that the biofilm created by ica-positive strains was different from biofilm formed by ica-negative strains. The MRSA population showed a large genetic diversity and we did not find a single clone that occurred preferentially in hospital environment. Our results demonstrated the variation in genes encoding adhesins for the host matrix proteins (elastin, laminin, collagen, fibronectin, and fibrinogen) and in the gene involved in biofilm formation (icaA) within the majority of S. aureus clones.

Amino Acid and Peptide Utilization Profiles of the Fluoroacetate-Degrading Bacterium Synergistetes Strain MFA1 Under Varying Conditions.

PubMed

Leong, Lex E X; Denman, Stuart E; Hugenholtz, Philip; McSweeney, Christopher S

2016-02-01

Synergistetes strain MFA1 is an asaccharolytic ruminal bacterium isolated based on its ability to degrade fluoroacetate, a plant toxin. The amino acid and peptide requirements of the bacterium were investigated under different culturing conditions. The growth of strain MFA1 and its fluoroacetate degradation rate were enhanced by peptide-rich protein hydrolysates (tryptone and yeast extract) compared to casamino acid, an amino acid-rich protein hydrolysate. Complete utilization and preference for arginine, asparagine, glutamate, glycine, and histidine as free amino acids from yeast extract were observed, while the utilization of serine, threonine, and lysine in free form and peptide-bound glutamate was stimulated during growth on fluoroacetate. A predominant peptide in yeast extract preferentially utilized by strain MFA1 was partially characterized by high-liquid performance chromatography-mass spectrometry as a hepta-glutamate oligopeptide. Similar utilization profiles of amino acids were observed between the co-culture of strain MFA1 with Methanobrevibacter smithii without fluoroacetate and pure strain MFA1 culture with fluoroacetate. This suggests that growth of strain MFA1 could be enhanced by a reduction of hydrogen partial pressure as a result of hydrogen removal by a methanogen or reduction of fluoroacetate.

Preferential flow estimates to an agricultural tile drain with implications for glyphosate transport

USGS Publications Warehouse

Stone, W.W.; Wilson, J.T.

2006-01-01

Agricultural subsurface drains, commonly referred to as tile drains, are potentially significant pathways for the movement of fertilizers and pesticides to streams and ditches in much of the Midwest. Preferential flow in the unsaturated zone provides a route for water and solutes to bypass the soil matrix and reach tile drains faster than predicted by traditional displacement theory. This paper uses chloride concentrations to estimate preferential flow contributions to a tile drain during two storms in May 2004. Chloride, a conservative anion, was selected as the tracer because of differences in chloride concentrations between the two sources of water to the tile drain, preferential and matrix flow. A strong correlation between specific conductance and chloride concentration provided a mechanism to estimate chloride concentrations in the tile drain throughout the storm hydrographs. A simple mixing analysis was used to identify the preferential flow component of the storm hydrograph. During two storms, preferential flow contributed 11 and 51% of total storm tile drain flow; the peak contributions, 40 and 81%, coincided with the peak tile drain flow. Positive relations between glyphosate [N-(phosphonomethyl)glycine] concentrations and preferential flow for the two storms suggest that preferential flow is an important transport pathway to the tile drain. ?? ASA, CSSA, SSSA.

Cone consumption by southeastern fox squirrels: A potential basis for clonal preferences in a loblolly and slash pine seed orchard

Treesearch

Christopher Asaro; Susan C. Loeb; James L. Hanula

2003-01-01

Southeastern fox squirrels were observed feeding preferentially on seeds of certain clones of loblolly pine in a central Georgia seed orchard in the early 1990s and, similarly, on slash pine seed in an orchard in central Florida in the late 1990s. In each orchard, the degree of feeding preference and avoidance among selected clones was documented and quantified. We...

Effects of load carrying on metabolic cost and hindlimb muscle dynamics in guinea fowl (Numida meleagris)

PubMed Central

McGowan, C. P.; Duarte, H. A.; Main, J. B.; Biewener, A. A.

2008-01-01

The goal of this study was to test whether the contractile patterns of two major hindlimb extensors of guinea fowl are altered by load-carrying exercise. We hypothesized that changes in contractile pattern, specifically a decrease in muscle shortening velocity or enhanced stretch activation, would result in a reduction in locomotor energy cost relative to the load carried. We also anticipated that changes in kinematics would reflect underlying changes in muscle strain. Oxygen consumption, muscle activation intensity, and fascicle strain rate were measured over a range of speeds while animals ran unloaded vs. when they carried a trunk load equal to 22% of their body mass. Our results showed that loading produced no significant (P > 0.05) changes in kinematic patterns at any speed. In vivo muscle contractile strain patterns in the iliotibialis lateralis pars postacetabularis and the medial head of the gastrocnemius showed a significant increase in active stretch early in stance (P < 0.01), but muscle fascicle shortening velocity was not significantly affected by load carrying. The rate of oxygen consumption increased by 17% (P < 0.01) during loaded conditions, equivalent to 77% of the relative increase in mass. Additionally, relative increases in EMG intensity (quantified as mean spike amplitude) indicated less than proportional recruitment, consistent with force enhancement via stretch activation, in the proximal iliotibialis lateralis pars postacetabularis; however, a greater than proportional increase in the medial gastrocnemius was observed. As a result, when averaged for the two muscles, EMG intensity increased in direct proportion to the fractional increase in load carried. PMID:16809624

Engineering Brevibacterium flavum for the production of renewable bioenergy: C4-C5 advanced alcohols.

PubMed

Su, HaiFeng; Lin, JiaFu; Wang, YuanHong; Chen, Qiao; Wang, GuangWei; Tan, FuRong

2017-09-01

Biosynthesis of advanced biofuels by engineered non-natural microorganisms has been proposed to be the most promising approach for the replacement of dwindling fossil fuel resources. Brevibacterium flavum (Bf) is a model brevibacterium aerobe which lacks basic and applied research that could enable this species to produce biofuels. There are no reports regarding engineering this microorganism to produce advanced alcohols before. Here, for the first time, we developed the bacterium as a novel biosynthetic platform for advanced alcohols production via the mutagenesis and engineering to produce 2-ketoacids derived alcohols. In order to enhance the strain's capability of producing advanced alcohols, we preferentially improved intrinsic metabolism ability of the strain to obtain improved expression host (IEH) via generating mutagenesis libraries by whole cell mutagenesis (WCM). The IEH was determined via screening out the mutant strain with the highest production of branched-chain organic acids (BCOA) using high throughput screening method.. Subsequently, a novel vector system for Bf was established, and the corresponding biosynthetic pathway of directing carbon flux into the target advanced alcohols was recruited to make the bacterium possess the capability of producing advanced alcohols and further enhance the production using the IEH. Specifically, we generated bioengineered strains that were able to synthesize up to the highest 5362 and 4976 mg/L isobutanol, 1945 and 1747 mg/L 2-methyl-1-butanol (2 MB), and 785.34 and 781 mg/L 3-methyl-1-butanol (3 MB) from pure glucose and duckweed substrates, respectively. Our findings confirmed the feasibility and potential of using Bf as a novel biosynthetic platform to generate advanced biofuels with glucose and inexpensive renewable feedstock-duckweed as a fermentation substrate. Biotechnol. Bioeng. 2017;114: 1946-1958. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Transcriptomic analysis reveals Toxoplasma gondii strain-specific differences in host cell response to dense granule protein GRA15.

PubMed

Liu, Qing; Gao, Wen-Wei; Elsheikha, Hany M; He, Jun-Jun; Li, Fa-Cai; Yang, Wen-Bin; Zhu, Xing-Quan

2018-06-19

Growth and replication of the protozoan parasite Toxoplasma gondii within host cell entail the production of several effector proteins, which the parasite exploits for counteracting the host's immune response. Despite considerable research to define the host signaling pathways manipulated by T. gondii and their effectors, there has been limited progress into understanding how individual members of the dense granule proteins (GRAs) modulate gene expression within host cells. The aim of this study was to evaluate whether T. gondii GRA15 protein plays any role in regulating host gene expression. Baby hamster kidney cells (BHK-21) were transfected with plasmids encoding GRA15 genes of either type I GT1 strain (GRA15 I ) or type II PRU strain (GRA15 II ). Gene expression patterns of transfected and nontransfected BHK-21 cells were investigated using RNA-sequencing analysis. GRA15 I and GRA15 II induced both known and novel transcriptional changes in the transfected BHK-21 cells compared with nontransfected cells. Pathway analysis revealed that GRA15 II was mainly involved in the regulation of tumor necrosis factor (TNF), NF-κB, HTLV-I infection, and NOD-like receptor signaling pathways. GRA15 I preferentially influenced the synthesis of unsaturated fatty acids in host cells. Our findings support the hypothesis that certain functions of GRA15 protein are strain dependent and that GRA15 modulates the expression of signaling pathways and genes with important roles in T. gondii pathophysiology. A greater understanding of host signaling pathways influenced by T. gondii effectors would allow the development of more efficient anti-T. gondii therapeutic schemes, capitalizing on disrupting parasite virulence factors to advance the treatment of toxoplasmosis.

Structure-based Analysis to Hu-DNA Binding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swinger,K.; Rice, P.

2007-01-01

HU and IHF are prokaryotic proteins that induce very large bends in DNA. They are present in high concentrations in the bacterial nucleoid and aid in chromosomal compaction. They also function as regulatory cofactors in many processes, such as site-specific recombination and the initiation of replication and transcription. HU and IHF have become paradigms for understanding DNA bending and indirect readout of sequence. While IHF shows significant sequence specificity, HU binds preferentially to certain damaged or distorted DNAs. However, none of the structurally diverse HU substrates previously studied in vitro is identical with the distorted substrates in the recently publishedmore » Anabaena HU(AHU)-DNA cocrystal structures. Here, we report binding affinities for AHU and the DNA in the cocrystal structures. The binding free energies for formation of these AHU-DNA complexes range from 10-14.5 kcal/mol, representing K{sub d} values in the nanomolar to low picomolar range, and a maximum stabilization of at least 6.3 kcal/mol relative to complexes with undistorted, non-specific DNA. We investigated IHF binding and found that appropriate structural distortions can greatly enhance its affinity. On the basis of the coupling of structural and relevant binding data, we estimate the amount of conformational strain in an IHF-mediated DNA kink that is relieved by a nick (at least 0.76 kcal/mol) and pinpoint the location of the strain. We show that AHU has a sequence preference for an A+T-rich region in the center of its DNA-binding site, correlating with an unusually narrow minor groove. This is similar to sequence preferences shown by the eukaryotic nucleosome.« less

Nutrigenetic screening strains of the mulberry silkworm, Bombyx mori, for nutritional efficiency.

PubMed

Ramesha, Chinnaswamy; Lakshmi, Hothur; Kumari, Savarapu Sugnana; Anuradha, Chevva M; Kumar, Chitta Suresh

2012-01-01

The activity of sericulture is declining due the reduction of mulberry production area in sericulture practicing countries lead to adverse effects on silkworm rearing and cocoon production. Screening for nutrigenetic traits in silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) is an essential prerequisite for better understanding and development of nutritionally efficient breeds/hybrids, which show less food consumption with higher efficiency conversion. The aim of this study was to identify nutritionally efficient polyvoltine silkworm strains using the germplasm breeds RMW(2), RMW(3), RMW(4), RMG(3), RMG(1), RMG(4), RMG(5), RMG(6) and APM(1) as the control. The 1(st) day of 5(th) stage silkworm larvae of polyvoltine strains were subjected to standard gravimetric analysis until spinning for three consecutive generations covering 3 different seasons on 19 nutrigenetic traits. Highly significant (p ≤ 0.001) differences were found among all nutrigenetic traits of polyvoltine silkworm strains in the experimental groups. The nutritionally efficient polvoltine silkworm strains were resulted by utilizing nutrition consumption index and efficiency of conversion of ingesta/cocoon traits as the index. Higher nutritional efficiency conversions were found in the polyvoltine silkworm strains on efficiency of conversion of ingesta to cocoon and shell than control. Comparatively smaller consumption index, respiration, metabolic rate with superior relative growth rate, and quantum of food ingesta and digesta requisite per gram of cocoon and shell were found; the lowest amount was in new polyvoltine strains compared to the control. Furthermore, based on the overall nutrigenetic traits utilized as index or 'biomarkers', three polyvoltine silkworm strains (RMG(4), RMW(2), and RMW(3)) were identified as having the potential for nutrition efficiency conversion. The data from the present study advances our knowledge for the development of nutritionally efficient silkworm breeds/hybrids and their effective commercial utilization in the sericulture industry.

Nutrigenetic screening strains of the mulberry silkworm, Bombyx mori, for nutritional efficiency.

PubMed

Chinnaswamy, Ramesha; Lakshmi, Hothur; Kumari, Savarapu S; Anuradha, Chebba M; Kumar, Chitta S

2012-01-01

The activity of sericulture is declining due the reduction of mulberry production area in sericulture practicing countries lead to adverse effects on silkworm rearing and cocoon production. Screening for nutrigenetic traits in silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) is an essential prerequisite for better understanding and development of nutritionally efficient breeds/hybrids, which show less food consumption with higher efficiency conversion. The aim of this study was to identify nutritionally efficient polyvoltine silkworm strains using the germplasm breeds RMW(2), RMW(3), RMW(4), RMG(3), RMG(1), RMG(4), RMG(5), RMG(6) and APM(1) as the control. The 1(st) day of 5(th) stage silkworm larvae of polyvoltine strains were subjected to standard gravimetric analysis until spinning for three consecutive generations covering three different seasons on 19 nutrigenetic traits. Highly significant (p ≤ 0.001) differences were found among all nutrigenetic traits of polyvoltine silkworm strains in the experimental groups. The nutritionally efficient polvoltine silkworm strains were resulted by utilizing nutrition consumption index and efficiency of conversion of ingesta/cocoon traits as the index. Higher nutritional efficiency conversions were found in the polyvoltine silkworm strains on efficiency of conversion of ingesta to cocoon and shell than control. Comparatively smaller consumption index, respiration, metabolic rate with superior relative growth rate, and quantum of food ingesta and digesta requisite per gram of cocoon and shell were shown; the lowest amount was in new polyvoltine strains compared to the control. Furthermore, based on the overall nutrigenetic traits utilized as index or 'biomarkers', three polyvoltine silkworm strains (RMG(4), RMW(2), and RMW(3)) were identified as having the potential for nutrition efficiency conversion. The data from the present study advances our knowledge for the development of nutritionally efficient silkworm breeds/hybrids and their effective commercial utilization in the sericulture industry.

Nutrigenetic Screening Strains of the Mulberry Silkworm, Bombyx mori, for Nutritional Efficiency

PubMed Central

Chinnaswamy, Ramesha; Lakshmi, Hothur; Kumari, Savarapu S.; Anuradha, Chebba M.; Kumar, Chitta S.

2012-01-01

The activity of sericulture is declining due the reduction of mulberry production area in sericulture practicing countries lead to adverse effects on silkworm rearing and cocoon production. Screening for nutrigenetic traits in silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) is an essential prerequisite for better understanding and development of nutritionally efficient breeds/hybrids, which show less food consumption with higher efficiency conversion. The aim of this study was to identify nutritionally efficient polyvoltine silkworm strains using the germplasm breeds RMW2, RMW3, RMW4, RMG3, RMG1, RMG4, RMG5, RMG6 and APM1 as the control. The 1st day of 5th stage silkworm larvae of polyvoltine strains were subjected to standard gravimetric analysis until spinning for three consecutive generations covering three different seasons on 19 nutrigenetic traits. Highly significant (p ≤ 0.001) differences were found among all nutrigenetic traits of polyvoltine silkworm strains in the experimental groups. The nutritionally efficient polvoltine silkworm strains were resulted by utilizing nutrition consumption index and efficiency of conversion of ingesta/cocoon traits as the index. Higher nutritional efficiency conversions were found in the polyvoltine silkworm strains on efficiency of conversion of ingesta to cocoon and shell than control. Comparatively smaller consumption index, respiration, metabolic rate with superior relative growth rate, and quantum of food ingesta and digesta requisite per gram of cocoon and shell were shown; the lowest amount was in new polyvoltine strains compared to the control. Furthermore, based on the overall nutrigenetic traits utilized as index or ‘biomarkers’, three polyvoltine silkworm strains (RMG4, RMW2, and RMW3) were identified as having the potential for nutrition efficiency conversion. The data from the present study advances our knowledge for the development of nutritionally efficient silkworm breeds/hybrids and their effective commercial utilization in the sericulture industry. PMID:22938037

Nutrigenetic Screening Strains of the Mulberry Silkworm, Bombyx mori, for Nutritional Efficiency

PubMed Central

Ramesha, Chinnaswamy; Lakshmi, Hothur; Kumari, Savarapu Sugnana; Anuradha, Chevva M.; Kumar, Chitta Suresh

2012-01-01

The activity of sericulture is declining due the reduction of mulberry production area in sericulture practicing countries lead to adverse effects on silkworm rearing and cocoon production. Screening for nutrigenetic traits in silkworm, Bombyx mori L. (Lepidoptera: Bombycidae) is an essential prerequisite for better understanding and development of nutritionally efficient breeds/hybrids, which show less food consumption with higher efficiency conversion. The aim of this study was to identify nutritionally efficient polyvoltine silkworm strains using the germplasm breeds RMW2, RMW3, RMW4, RMG3, RMG1, RMG4, RMG5, RMG6 and APM1 as the control. The 1st day of 5th stage silkworm larvae of polyvoltine strains were subjected to standard gravimetric analysis until spinning for three consecutive generations covering 3 different seasons on 19 nutrigenetic traits. Highly significant (p ≤ 0.001) differences were found among all nutrigenetic traits of polyvoltine silkworm strains in the experimental groups. The nutritionally efficient polvoltine silkworm strains were resulted by utilizing nutrition consumption index and efficiency of conversion of ingesta/cocoon traits as the index. Higher nutritional efficiency conversions were found in the polyvoltine silkworm strains on efficiency of conversion of ingesta to cocoon and shell than control. Comparatively smaller consumption index, respiration, metabolic rate with superior relative growth rate, and quantum of food ingesta and digesta requisite per gram of cocoon and shell were found; the lowest amount was in new polyvoltine strains compared to the control. Furthermore, based on the overall nutrigenetic traits utilized as index or ‘biomarkers’, three polyvoltine silkworm strains (RMG4, RMW2, and RMW3) were identified as having the potential for nutrition efficiency conversion. The data from the present study advances our knowledge for the development of nutritionally efficient silkworm breeds/hybrids and their effective commercial utilization in the sericulture industry. PMID:22934597

A family cluster of hepatitis A virus due to an uncommon IA strain circulating in Campania (southern Italy), not associated with raw shellfish or berries: a wake-up call to implement vaccination against hepatitis A?

PubMed

Tosone, Grazia; Mascolo, Silvia; Bruni, Roberto; Taffon, Stefania; Equestre, Michele; Tosti, Maria Elena; Ciccaglione, Anna Rita; Martucci, Fiorella; Liberti, Alfonso; Iannece, Maria Donata; Orlando, Raffaele

2016-09-01

Hepatitis A virus is a widely occurring disease, with different prevalence rates between countries in the North and West and those in the South and East. In Italy endemicity is low/medium, but not homogeneously distributed: in the northern/central regions a large hepatitis A outbreak due to genotype IA, related to the consumption of contaminated mixed frozen berries, occurred between 2013 and 2014, whereas in southern Italian regions recurrent outbreaks of hepatitis A, due to the IB genotype, still result from consumption of raw seafood. In 2014 an uncommon genotype IA strain was isolated from five patients (2 adults and 3 children) with hepatitis A, living in the surroundings of Naples (Campania) who did not have any of the most common risk factors for hepatitis A in Italy, such as consumption of raw shellfish or frozen berries, or travel to endemic countries. Moreover, based on the analysis of viral sequences obtained, this strain differed from several others in the national database, which had been recently isolated during Italian outbreaks. This case report reinforces the need to implement both information campaigns about the prevention of hepatitis A and vaccination programmes in childhood; in addition, it would be suitable to sequence strains routinely not only during large outbreaks of hepatitis A in order to obtain a more detailed national database of HAV strains circulating in Italy.

Specification of Cortical Parenchyma and Stele of Maize Primary Roots by Asymmetric Levels of Auxin, Cytokinin, and Cytokinin-Regulated Proteins1[C][W][OA

PubMed Central

Saleem, Muhammad; Lamkemeyer, Tobias; Schützenmeister, André; Madlung, Johannes; Sakai, Hajime; Piepho, Hans-Peter; Nordheim, Alfred; Hochholdinger, Frank

2010-01-01

In transverse orientation, maize (Zea mays) roots are composed of a central stele that is embedded in multiple layers of cortical parenchyma. The stele functions in the transport of water, nutrients, and photosynthates, while the cortical parenchyma fulfills metabolic functions that are not very well characterized. To better understand the molecular functions of these root tissues, protein- and phytohormone-profiling experiments were conducted. Two-dimensional gel electrophoresis combined with electrospray ionization tandem mass spectrometry identified 59 proteins that were preferentially accumulated in the cortical parenchyma and 11 stele-specific proteins. Hormone profiling revealed preferential accumulation of indole acetic acid and its conjugate indole acetic acid-aspartate in the stele and predominant localization of the cytokinin cis-zeatin, its precursor cis-zeatin riboside, and its conjugate cis-zeatin O-glucoside in the cortical parenchyma. A root-specific β-glucosidase that functions in the hydrolysis of cis-zeatin O-glucoside was preferentially accumulated in the cortical parenchyma. Similarly, four enzymes involved in ammonium assimilation that are regulated by cytokinin were preferentially accumulated in the cortical parenchyma. The antagonistic distribution of auxin and cytokinin in the stele and cortical parenchyma, together with the cortical parenchyma-specific accumulation of cytokinin-regulated proteins, suggest a molecular framework that specifies the function of these root tissues that also play a role in the formation of lateral roots from pericycle and endodermis cells. PMID:19933382

Influence of localized plasticity on oxidation behaviour of austenitic stainless steels under primary water reactor

NASA Astrophysics Data System (ADS)

Cissé, Sarata; Laffont, Lydia; Lafont, Marie-Christine; Tanguy, Benoit; Andrieu, Eric

2013-02-01

The sensitivity of precipitation-strengthened A286 austenitic stainless steel to stress corrosion cracking was studied by means of slow-strain-rate tests. First, alloy cold working by low cycle fatigue (LCF) was investigated. Fatigue tests under plastic strain control were performed at different strain levels (Δɛp/2 = 0.2%, 0.5%, 0.8% and 2%) to establish correlations between stress softening and the deformation microstructure resulting from the LCF tests. Deformed microstructures were identified through TEM investigations. The interaction between oxidation and localized deformation bands was also studied and it resulted that localized deformation bands are not preferential oxide growth channels. The pre-cycling of the alloy did not modify its oxidation behaviour. However, intergranular oxidation in the subsurface under the oxide layer formed after exposure to PWR primary water was shown.

Stokes Approach to Preferential Flow at the Darcy-Scale

NASA Astrophysics Data System (ADS)

Germann, Peter; Bogner, Christina

2017-04-01

Preferential Flow in soils is fast, limited to infiltration and occupies but a small portion of porosity. However, how fast is it, how much water is involved, what is its flow rate, and how far is it carried? Supported with numerous measurements a Stokes approach to preferential flow provides the answers at the operational Darcy-scale. The approach to preferential flow in permeable media (pm) stresses momentum dissipation during viscous flow. Thus, a laminar water film percolates through a pm. The dynamic film is initially determined by the thickness F (m) and the specific contact area L (m2 m-3) per unit volume of the medium. Input to the medium's surface is a pulse with volume flux density q (ms-1) that starts and ends at times TB and TE. A specific pulse and the intrinsic properties of a pm determine F and L. A water content wave (WCW) envelops the spatio-temporal evolution of a water film. A WCW is completely described with a set of analytical relationships that are based on F, L, and the water's viscosity. The approach is an extension of Hagen-Poiseuille's law of flow in concentric conduits. It also evolves seamlessly from extending Darcy's law into non-saturated pm. Experimental determination of F and L follows either from drainage flow or from rapid soil moisture recordings during the passing of a WCW, for instance, with TDR-equipment. Parameters from numerous infiltration experiments in the field, in soil columns, in sand boxes, and lysimeters demonstrate the approach's broad applicability, thus framing the spatio-temporal extensions, velocities and volume flux densities of preferential flows. The specific contact area L is considered the locus of water, heat, particle and solute transfer between a WCW and the sessile parts of a pm. A recent analysis of delayed Br-breakthrough with respect to drainage flow supports the feasibility of the Stokes approach to preferential flow at the Darcy-scale. A perspective of modeling sequences of input pulses will conclude the presentation.

Putative Novel Genotype of Avian Hepatitis E Virus, Hungary, 2010

PubMed Central

Bányai, Krisztián; Tóth, Ádám György; Ivanics, Éva; Glávits, Róbert; Szentpáli-Gavallér, Katalin

2012-01-01

To explore the genetic diversity of avian hepatitis E virus strains, we characterized the near-complete genome of a strain detected in 2010 in Hungary, uncovering moderate genome sequence similarity with reference strains. Public health implications related to consumption of eggs or meat contaminated by avian hepatitis E virus, or to poultry handling, require thorough investigation. PMID:22840214

Mineralization of LCFA associated with anaerobic sludge: Kinetics, enhancement of methanogenic activity, and effect of VFA.

PubMed

Pereira, M A; Sousa, D Z; Mota, M; Alves, M M

2004-11-20

Long-chain fatty acids (LCFA) associated with anaerobic sludge by mechanisms of precipitation, adsorption, or entrapment can be biodegraded to methane. The mineralization kinetics of biomass-associated LCFA were established according to an inhibition model based on Haldane's enzymatic inhibition kinetics. A value around 1,000 mg COD-LCFA..g VSS(-1) was obtained for the optimal specific LCFA content that allowed the maximal mineralization rate. For sludge with specific LCFA contents of 2,838 +/- 63 and 4,571 +/- 257 mg COD-LCFA..g VSS(-1), the specific methanogenic activities in the presence of acetate, butyrate, and H(2)/CO(2) were significantly enhanced after the mineralization of the biomass-associated LCFA. For sludge with a specific LCFA content near the optimal value defined by the kinetic model, the effect of adding VFA to the medium was studied during the mineralization of the biomass-associated LCFA. Different patterns were obtained for each individual substrate. Acetate and butyrate were preferentially consumed by the consortium, but in the case of propionate no evidence of a sequential consumption pattern could be withdrawn. It was concluded that LCFA do not exert a bactericidal neither a permanent toxic effect toward the anaerobic consortia. A discussion is addressed to the relative roles of a reversible inhibitory effect and a transport limitation effect imposed by the LCFA surrounding the cells. (c) 2004 Wiley Periodicals, Inc

Molecular cloning, characterization and comparison of bile salt hydrolases from Lactobacillus johnsonii PF01.

PubMed

Chae, J P; Valeriano, V D; Kim, G-B; Kang, D-K

2013-01-01

To clone, characterize and compare the bile salt hydrolase (BSH) genes of Lactobacillus johnsonii PF01. The BSH genes were amplified by polymerase chain reaction (PCR) using specific oligonucleotide primers, and the products were inserted into the pET21b expression vector. Escherichia coli BLR (DE3) cells were transformed with pET21b vectors containing the BSH genes and induced using 0·1 mmol l(-1) isopropylthiolgalactopyranoside. The overexpressed BSH enzymes were purified using a nickel-nitrilotriacetic acid (Ni(2+) -NTA) agarose column and their activities characterized. BSH A hydrolysed tauro-conjugated bile salts optimally at pH 5·0 and 55°C, whereas BSH C hydrolysed glyco-conjugated bile salts optimally at pH 5·0 and 70°C. The enzymes had no preferential activities towards a specific cholyl moiety. BSH enzymes vary in their substrate specificities and characteristics to broaden its activity. Despite the lack of conservation in their putative substrate-binding sites, these remain functional through motif conservation. This is to our knowledge the first report of isolation of BSH enzymes from a single strain, showing hydrolase activity towards either glyco-conjugated or tauro-conjugated bile salts. Future structural homology studies and site-directed mutagenesis of sites associated with substrate specificity may elucidate specificities of BSH enzymes. © 2012 The Society for Applied Microbiology.

Directed combinatorial mutagenesis of Escherichia coli for complex phenotype engineering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Rongming; Liang, Liya; Garst, Andrew D.

Strain engineering for industrial production requires a targeted improvement of multiple complex traits, which range from pathway flux to tolerance to mixed sugar utilization. Here, we report the use of an iterative CRISPR EnAbled Trackable genome Engineering (iCREATE) method to engineer rapid glucose and xylose co-consumption and tolerance to hydrolysate inhibitors in E. coli. Deep mutagenesis libraries were rationally designed, constructed, and screened to target ~40,000 mutations across 30 genes. These libraries included global and high-level regulators that regulate global gene expression, transcription factors that play important roles in genome-level transcription, enzymes that function in the sugar transport system, NAD(P)Hmore » metabolism, and the aldehyde reduction system. Specific mutants that conferred increased growth in mixed sugars and hydrolysate tolerance conditions were isolated, confirmed, and evaluated for changes in genome-wide expression levels. As a result, we tested the strain with positive combinatorial mutations for 3-hydroxypropionic acid (3HP) production under high furfural and high acetate hydrolysate fermentation, which demonstrated a 7- and 8-fold increase in 3HP productivity relative to the parent strain, respectively.« less

Directed combinatorial mutagenesis of Escherichia coli for complex phenotype engineering

DOE PAGES

Liu, Rongming; Liang, Liya; Garst, Andrew D.; ...

2018-03-29

Strain engineering for industrial production requires a targeted improvement of multiple complex traits, which range from pathway flux to tolerance to mixed sugar utilization. Here, we report the use of an iterative CRISPR EnAbled Trackable genome Engineering (iCREATE) method to engineer rapid glucose and xylose co-consumption and tolerance to hydrolysate inhibitors in E. coli. Deep mutagenesis libraries were rationally designed, constructed, and screened to target ~40,000 mutations across 30 genes. These libraries included global and high-level regulators that regulate global gene expression, transcription factors that play important roles in genome-level transcription, enzymes that function in the sugar transport system, NAD(P)Hmore » metabolism, and the aldehyde reduction system. Specific mutants that conferred increased growth in mixed sugars and hydrolysate tolerance conditions were isolated, confirmed, and evaluated for changes in genome-wide expression levels. As a result, we tested the strain with positive combinatorial mutations for 3-hydroxypropionic acid (3HP) production under high furfural and high acetate hydrolysate fermentation, which demonstrated a 7- and 8-fold increase in 3HP productivity relative to the parent strain, respectively.« less

A Nonautochthonous U.S. Strain of Vibrio parahaemolyticus Isolated from Chesapeake Bay Oysters Caused the Outbreak in Maryland in 2010

PubMed Central

Haendiges, Julie; Jones, Jessica; Myers, Robert A.; Mitchell, Clifford S.; Butler, Erin

2016-01-01

ABSTRACT In the summer of 2010, Vibrio parahaemolyticus caused an outbreak in Maryland linked to the consumption of oysters. Strains isolated from both stool and oyster samples were indistinguishable by pulsed-field gel electrophoresis (PFGE). However, the oysters contained other potentially pathogenic V. parahaemolyticus strains exhibiting different PFGE patterns. In order to assess the identity, genetic makeup, relatedness, and potential pathogenicity of the V. parahaemolyticus strains, we sequenced 11 such strains (2 clinical strains and 9 oyster strains). We analyzed these genomes by in silico multilocus sequence typing (MLST) and determined their phylogeny using a whole-genome MLST (wgMLST) analysis. Our in silico MLST analysis identified six different sequence types (STs) (ST8, ST676, ST810, ST811, ST34, and ST768), with both of the clinical and four of the oyster strains being identified as belonging to ST8. Using wgMLST, we showed that the ST8 strains from clinical and oyster samples were nearly indistinguishable and belonged to the same outbreak, confirming that local oysters were the source of the infections. The remaining oyster strains were genetically diverse, differing in >3,000 loci from the Maryland ST8 strains. eBURST analysis comparing these strains with strains of other STs available at the V. parahaemolyticus MLST website showed that the Maryland ST8 strains belonged to a clonal complex endemic to Asia. This indicates that the ST8 isolates from clinical and oyster sources were likely not endemic to Maryland. Finally, this study demonstrates the utility of whole-genome sequencing (WGS) and associated analyses for source-tracking investigations. IMPORTANCE Vibrio parahaemolyticus is an important foodborne pathogen and the leading cause of bacterial infections in the United States associated with the consumption of seafood. In the summer of 2010, Vibrio parahaemolyticus caused an outbreak in Maryland linked to oyster consumption. Strains isolated from stool and oyster samples were indistinguishable by pulsed-field gel electrophoresis (PFGE). The oysters also contained other potentially pathogenic V. parahaemolyticus strains with different PFGE patterns. Since their identity, genetic makeup, relatedness, and potential pathogenicity were unknown, their genomes were determined by using next-generation sequencing. Whole-genome sequencing (WGS) analysis by whole-genome multilocus sequence typing (wgMLST) allowed (i) identification of clinical and oyster strains with matching PFGE profiles as belonging to ST8, (ii) determination of oyster strain diversity, and (iii) identification of the clinical strains as belonging to a clonal complex (CC) described only in Asia. Finally, WGS and associated analyses demonstrated their utility for trace-back investigations. PMID:26994080

A Nonautochthonous U.S. Strain of Vibrio parahaemolyticus Isolated from Chesapeake Bay Oysters Caused the Outbreak in Maryland in 2010.

PubMed

Haendiges, Julie; Jones, Jessica; Myers, Robert A; Mitchell, Clifford S; Butler, Erin; Toro, Magaly; Gonzalez-Escalona, Narjol

2016-06-01

In the summer of 2010, Vibrio parahaemolyticus caused an outbreak in Maryland linked to the consumption of oysters. Strains isolated from both stool and oyster samples were indistinguishable by pulsed-field gel electrophoresis (PFGE). However, the oysters contained other potentially pathogenic V. parahaemolyticus strains exhibiting different PFGE patterns. In order to assess the identity, genetic makeup, relatedness, and potential pathogenicity of the V. parahaemolyticus strains, we sequenced 11 such strains (2 clinical strains and 9 oyster strains). We analyzed these genomes by in silico multilocus sequence typing (MLST) and determined their phylogeny using a whole-genome MLST (wgMLST) analysis. Our in silico MLST analysis identified six different sequence types (STs) (ST8, ST676, ST810, ST811, ST34, and ST768), with both of the clinical and four of the oyster strains being identified as belonging to ST8. Using wgMLST, we showed that the ST8 strains from clinical and oyster samples were nearly indistinguishable and belonged to the same outbreak, confirming that local oysters were the source of the infections. The remaining oyster strains were genetically diverse, differing in >3,000 loci from the Maryland ST8 strains. eBURST analysis comparing these strains with strains of other STs available at the V. parahaemolyticus MLST website showed that the Maryland ST8 strains belonged to a clonal complex endemic to Asia. This indicates that the ST8 isolates from clinical and oyster sources were likely not endemic to Maryland. Finally, this study demonstrates the utility of whole-genome sequencing (WGS) and associated analyses for source-tracking investigations. Vibrio parahaemolyticus is an important foodborne pathogen and the leading cause of bacterial infections in the United States associated with the consumption of seafood. In the summer of 2010, Vibrio parahaemolyticus caused an outbreak in Maryland linked to oyster consumption. Strains isolated from stool and oyster samples were indistinguishable by pulsed-field gel electrophoresis (PFGE). The oysters also contained other potentially pathogenic V. parahaemolyticus strains with different PFGE patterns. Since their identity, genetic makeup, relatedness, and potential pathogenicity were unknown, their genomes were determined by using next-generation sequencing. Whole-genome sequencing (WGS) analysis by whole-genome multilocus sequence typing (wgMLST) allowed (i) identification of clinical and oyster strains with matching PFGE profiles as belonging to ST8, (ii) determination of oyster strain diversity, and (iii) identification of the clinical strains as belonging to a clonal complex (CC) described only in Asia. Finally, WGS and associated analyses demonstrated their utility for trace-back investigations. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Turbulence-flame interactions in DNS of a laboratory high Karlovitz premixed turbulent jet flame

NASA Astrophysics Data System (ADS)

Wang, Haiou; Hawkes, Evatt R.; Chen, Jacqueline H.

2016-09-01

In the present work, direct numerical simulation (DNS) of a laboratory premixed turbulent jet flame was performed to study turbulence-flame interactions. The turbulent flame features moderate Reynolds number and high Karlovitz number (Ka). The orientations of the flame normal vector n, the vorticity vector ω and the principal strain rate eigenvectors ei are examined. The in-plane and out-of-plane angles are introduced to quantify the vector orientations, which also measure the flame geometry and the vortical structures. A general observation is that the distributions of these angles are more isotropic downstream as the flame and the flow become more developed. The out-of-plane angle of the flame normal vector, β, is a key parameter in developing the correction of 2D measurements to estimate the corresponding 3D quantities. The DNS results show that the correction factor is unity at the inlet and approaches its theoretical value of an isotropic distribution downstream. The alignment characteristics of n, ω and ei, which reflect the interactions of turbulence and flame, are also studied. Similar to a passive scalar gradient in non-reacting flows, the flame normal has a tendency to align with the most compressive strain rate, e3, in the flame, indicating that turbulence contributes to the production of scalar gradient. The vorticity dynamics are examined via the vortex stretching term, which was found to be the predominant source of vorticity generation balanced by dissipation, in the enstrophy transport equation. It is found that although the vorticity preferentially aligns with the intermediate strain rate, e2, the contribution of the most extensive strain rate, e1, to vortex stretching is comparable with that of the intermediate strain rate, e2. This is because the eigenvalue of the most extensive strain rate, λ1, is always large and positive. It is confirmed that the vorticity vector is preferentially positioned along the flame tangential plane, contributing to the dominance of cylindrical curvature of the flame front. Finally, the effect of heat release on the turbulence-flame interactions is examined. It is found that heat release has only limited impact on the statistics due to the minor role played by the strain rate induced by heat release rate in the current high Ka flame.

Improved hydrogen production under microaerophilic conditions by overexpression of polyphosphate kinase in Enterobacter aerogenes.

PubMed

Lu, Yuan; Zhang, Chong; Lai, Qiheng; Zhao, Hongxin; Xing, Xin-Hui

2011-02-08

Effects of different microaerophilic conditions on cell growth, glucose consumption, hydrogen production and cellular metabolism of wild Enterobacter aerogenes strain and polyphosphate kinase (PPK) overexpressing strain were systematically studied in this paper, using NaH(2)PO(4) as the phosphate sources. Under different microaerophilic conditions, PPK-overexpressing strain showed better cell growth, glucose consumption and hydrogen production than the wild strain. In the presence of limited oxygen (2.1%) and by PPK overexpression, the hydrogen production per liter of culture, the hydrogen production per cell and the hydrogen yield per mol of glucose increased by 20.1%, 12.3% and 10.8%, respectively, compared with the wild strain under strict anaerobic conditions. Metabolic analysis showed that the increase of the total hydrogen yield was attributed to the improvement of NADH pathway. The result of more reductive cellular oxidation state balance also further demonstrated that, under proper initial microaerophilic conditions and by PPK overexpression, the cell could adjust the cellular redox states and make more energy flow into hydrogen production pathways. Copyright © 2010 Elsevier Inc. All rights reserved.

Pityriazepin and other potent AhR ligands isolated from Malassezia furfur yeast

PubMed Central

Mexia, Nikitia; Gaitanis, George; Velegraki, Aristea; Soshilov, Anatoly; Denison, Michael S.; Magiatis, Prokopios

2015-01-01

Malassezia furfur yeast strains isolated from diseased human skin preferentially biosynthesize indole alkaloids which can be detected in human skin and are highly potent activators of the aryl hydrocarbon receptor (AhR) and AhR-dependent gene expression. Chemical analysis of an EtOAc extract of a M. furfur strain obtained from diseased human skin and grown on L-tryptophan agar revealed several known AhR active tryptophan metabolites along with a previously unidentified compound, pityriazepin. While its structure resembled that of the known alkaloid pityriacitrin, the comprised pyridine ring had been transformed into an azepinone. The indoloazepinone scaffold of pityriazepin is extremely rare in nature and has only been reported once previously. Pityriazepin, like the other isolated compounds, was found to be a potent activator of the AhR-dependent reporter gene assays in recombinant cell lines derived from four different species, although significant species differences in relative potency was observed. The ability of pityriazepin to competitively bind to the AhR and directly stimulate AhR DNA binding classified it as a new naturally-occurring potent AhR agonist. Malassezia furfur produces an expanded collection of extremely potent naturally occurring AhR agonists, which produce their biological effects in a species-specific manner.1 PMID:25721496

Genomic and chromatin features shaping meiotic double-strand break formation and repair in mice

PubMed Central

Jasin, Maria; Lange, Julian

2017-01-01

ABSTRACT The SPO11-generated DNA double-strand breaks (DSBs) that initiate meiotic recombination occur non-randomly across genomes, but mechanisms shaping their distribution and repair remain incompletely understood. Here, we expand on recent studies of nucleotide-resolution DSB maps in mouse spermatocytes. We find that trimethylation of histone H3 lysine 36 around DSB hotspots is highly correlated, both spatially and quantitatively, with trimethylation of H3 lysine 4, consistent with coordinated formation and action of both PRDM9-dependent histone modifications. In contrast, the DSB-responsive kinase ATM contributes independently of PRDM9 to controlling hotspot activity, and combined action of ATM and PRDM9 can explain nearly two-thirds of the variation in DSB frequency between hotspots. DSBs were modestly underrepresented in most repetitive sequences such as segmental duplications and transposons. Nonetheless, numerous DSBs form within repetitive sequences in each meiosis and some classes of repeats are preferentially targeted. Implications of these findings are discussed for evolution of PRDM9 and its role in hybrid strain sterility in mice. Finally, we document the relationship between mouse strain-specific DNA sequence variants within PRDM9 recognition motifs and attendant differences in recombination outcomes. Our results provide further insights into the complex web of factors that influence meiotic recombination patterns. PMID:28820351

Dealloyed Pt3Co nanoparticles with higher geometric strain for superior hydrogen evolution reaction

NASA Astrophysics Data System (ADS)

Saquib, Mohammad; Halder, Aditi

2018-06-01

In the present work, the effect of surface strain in the carbon supported Pt3Co dealloy catalyst towards hydrogen evolution reaction (HER) has been reported. Dealloying process is adopted to generate the geometric strain in Pt3Co/C alloy by preferential dissolution of non-noble metal (Co) from the alloy. The developed geometric strain has been estimated by different microstructural characterization techniques. Electrochemical studies showed that the highest current density for HER was obtained for Pt3Co/C dealloy catalyst and it was nearly 2 and 5 times higher than Pt3Co/C alloy and Pt/C respectively. Tafel slope for HER was improved from 49 (Pt/C) to 34 mV dec-1 (Pt3Co/C dealloy), indicating that the surface strain plays important role in the improvement of the catalytic activity of Pt3Co catalyst. The chronoamperometry data, LSV curves and ECSA values before and after chronoamperometry confirmed that Pt3Co/C dealloy catalyst was a stable as well as a durable electrocatalyst for HER.

Dependence of the optical conductivity on the uniaxial and biaxial strains in black phosphorene

NASA Astrophysics Data System (ADS)

Yang, C. H.; Zhang, J. Y.; Wang, G. X.; Zhang, C.

2018-06-01

By using the Kubo formula, the optical conductivity of strained black phosphorene was studied. The anisotropic band dispersion gives rise to an orientation dependent optical conductivity. The energy gap can be tuned by the uniaxial and biaxial strains which can be observed from the interband optical conductivity polarized along the armchair (x ) direction. The preferential conducting direction is along the x direction. The dependence of the intraband optical conductivity along the zigzag (y ) direction on the Fermi energy and strain exhibits increasing or decreasing monotonously. However, along the x direction this dependence is complicated which originates from the carriers' inverse-direction movements obtained by two types of the nearest phosphorus atom interactions. The modification of the biaxial strain on the energy structure and optical-absorption property is more effective. The imaginary part of the total optical conductivity (Im σ ) can be negative around the threshold of the interband optical transition by modifying the chemical potential. Away from this frequency region, Im σ exhibits positive value. It can be used in the application of the surface plasmon propagations in multilayer dielectric structures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahashi, Takeshi, E-mail: takeshi-takahashi@ciea.or.jp; Katano, Ikumi; Ito, Ryoji

Highlights: • β-Lactoglobulin (BLG) specific TCR genes were introduced to human HSC by retrovirus. • Human HSC with BLG-specific TCR were transplanted into NOG-HLA-DR4 I-A{sup −/−} mice. • BLG-specific TCR induced positive selection of thymocytes. • BLG-specific TCR positive CD4{sup +} T cells mediated immune responses in humanized mice. - Abstract: The development of severe immunodeficient mouse strains containing various human genes, including cytokines or HLA, has enabled the reconstitution of functional human immune systems after transplantation of human hematopoietic stem cells (HSC). Accumulating evidence has suggested that HLA-restricted antigen-specific human T-cell responses can be generated in these humanized mice.more » To directly monitor immune responses of human CD4{sup +} T cells, we introduced β-lactoglobulin (BLG)-specific T cell receptor (TCR) genes derived from CD4{sup +} T-cell clones of cow-milk allergy patients into HSCs, and subsequently transplanted them into NOG-HLA-DR4 transgenic/I-Aβ deficient mice (NOG-DR4/I-A{sup o}). In the thymus, thymocytes with BLG-specific TCR preferentially differentiated into CD4{sup +}CD8{sup −} single-positive cells. Adoptive transfer of mature CD4{sup +} T cells expressing the TCR into recipient NOG-DR4/I-A{sup o} mice demonstrated that human CD4{sup +} T cells proliferated in response to antigenic stimulation and produced IFN-γ in vivo, suggesting that functional T-cell reactions (especially Th1-skewed responses) were induced in humanized mice.« less

Preferrential Concentration of Particles in Protoplanetary Nebula Turbulence

NASA Technical Reports Server (NTRS)

Hartlep, Thomas; Cuzzi, Jeffrey N.

2015-01-01

Preferential concentration in turbulence is a process that causes inertial particles to cluster in regions of high strain (in-between high vorticity regions), with specifics depending on their stopping time or Stokes number. This process is thought to be of importance in various problems including cloud droplet formation and aerosol transport in the atmosphere, sprays, and also in the formation of asteroids and comets in protoplanetary nebulae. In protoplanetary nebulae, the initial accretion of primitive bodies from freely-floating particles remains a problematic subject. Traditional growth-by-sticking models encounter a formidable "meter-size barrier" [1] in turbulent nebulae. One scenario that can lead directly from independent nebula particulates to large objects, avoiding the problematic m-km size range, involves formation of dense clumps of aerodynamically selected, typically mm-size particles in protoplanetary turbulence. There is evidence that at least the ordinary chondrite parent bodies were initially composed entirely of a homogeneous mix of such particles generally known as "chondrules" [2]. Thus, while it is arcane, turbulent preferential concentration acting directly on chondrule size particles are worthy of deeper study. Here, we present the statistical determination of particle multiplier distributions from numerical simulations of particle-laden isotopic turbulence, and a cascade model for modeling turbulent concentration at lengthscales and Reynolds numbers not accessible by numerical simulations. We find that the multiplier distributions are scale dependent at the very largest scales but have scale-invariant properties under a particular variable normalization at smaller scales.

Deformation mechanism study of a hot rolled Zr-2.5Nb alloy by transmission electron microscopy. I. Dislocation microstructures in as-received state and at different plastic strains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, Fei; Daymond, Mark R., E-mail: mark.daymond@queensu.ca; Yao, Zhongwen

Thin foil dog bone samples prepared from a hot rolled Zr-2.5Nb alloy have been deformed by tensile deformation to different plastic strains. The development of slip traces during loading was observed in situ through SEM, revealing that deformation starts preferentially in certain sets of grains during the elastic-plastic transition region. TEM characterization showed that sub-grain boundaries formed during hot rolling consisted of screw 〈a〉 dislocations or screw 〈c〉 and 〈a〉 dislocations. Prismatic 〈a〉 dislocations with large screw or edge components have been identified from the sample with 0.5% plastic strain. Basal 〈a〉 and pyramidal 〈c + a〉 dislocations were found in themore » sample that had been deformed with 1.5% plastic strain, implying that these dislocations require larger stresses to be activated.« less

On mechanical mechanism of damage evolution in articular cartilage.

PubMed

Men, Yu-Tao; Jiang, Yan-Long; Chen, Ling; Zhang, Chun-Qiu; Ye, Jin-Duo

2017-09-01

Superficial lesions of cartilage are the direct indication of osteoarthritis. To investigate the mechanical mechanism of cartilage with micro-defect under external loading, a new plain strain numerical model with micro-defect was proposed and damage evolution progression in cartilage over time has been simulated, the parameter were studied including load style, velocity of load and degree of damage. The new model consists of the hierarchical structure of cartilage and depth-dependent arched fibers. The numerical results have shown that not only damage of the cartilage altered the distribution of the stress but also matrix and fiber had distinct roles in affecting cartilage damage, and damage in either matrix or fiber could promote each other. It has been found that the superficial cracks in cartilage spread preferentially along the tangent direction of the fibers. It is the arched distribution form of fibers that affects the crack spread of cartilage, which has been verified by experiment. During the process of damage evolution, its extension direction and velocity varied constantly with the damage degree. The rolling load could cause larger stress and strain than sliding load. Strain values of the matrix initially increased and then decreased gradually with the increase of velocity, and velocity had a greater effect on matrix than fibers. Damage increased steadily before reaching 50%, sharply within 50 to 85%, and smoothly and slowly after 85%. The finding of the paper may help to understand the mechanical mechanism why the cracks in cartilage spread preferentially along the tangent direction of the fibers. Copyright © 2017 Elsevier B.V. All rights reserved.

Motility and Chemotaxis Mediate the Preferential Colonization of Gastric Injury Sites by Helicobacter pylori

PubMed Central

Aihara, Eitaro; Closson, Chet; Matthis, Andrea L.; Schumacher, Michael A.; Engevik, Amy C.; Zavros, Yana; Ottemann, Karen M.; Montrose, Marshall H.

2014-01-01

Helicobacter pylori (H. pylori) is a pathogen contributing to peptic inflammation, ulceration, and cancer. A crucial step in the pathogenic sequence is when the bacterium first interacts with gastric tissue, an event that is poorly understood in vivo. We have shown that the luminal space adjacent to gastric epithelial damage is a microenvironment, and we hypothesized that this microenvironment might enhance H. pylori colonization. Inoculation with 106 H. pylori (wild-type Sydney Strain 1, SS1) significantly delayed healing of acetic-acid induced ulcers at Day 1, 7 and 30 post-inoculation, and wild-type SS1 preferentially colonized the ulcerated area compared to uninjured gastric tissue in the same animal at all time points. Gastric resident Lactobacillus spp. did not preferentially colonize ulcerated tissue. To determine whether bacterial motility and chemotaxis are important to ulcer healing and colonization, we analyzed isogenic H. pylori mutants defective in motility (ΔmotB) or chemotaxis (ΔcheY). ΔmotB (106) failed to colonize ulcerated or healthy stomach tissue. ΔcheY (106) colonized both tissues, but without preferential colonization of ulcerated tissue. However, ΔcheY did modestly delay ulcer healing, suggesting that chemotaxis is not required for this process. We used two-photon microscopy to induce microscopic epithelial lesions in vivo, and evaluated accumulation of fluorescently labeled H. pylori at gastric damage sites in the time frame of minutes instead of days. By 5 min after inducing damage, H. pylori SS1 preferentially accumulated at the site of damage and inhibited gastric epithelial restitution. H. pylori ΔcheY modestly accumulated at the gastric surface and inhibited restitution, but did not preferentially accumulate at the injury site. H. pylori ΔmotB neither accumulated at the surface nor inhibited restitution. We conclude that bacterial chemosensing and motility rapidly promote H. pylori colonization of injury sites, and thereby biases the injured tissue towards sustained gastric damage. PMID:25033386

Motility and chemotaxis mediate the preferential colonization of gastric injury sites by Helicobacter pylori.

PubMed

Aihara, Eitaro; Closson, Chet; Matthis, Andrea L; Schumacher, Michael A; Engevik, Amy C; Zavros, Yana; Ottemann, Karen M; Montrose, Marshall H

2014-07-01

Helicobacter pylori (H. pylori) is a pathogen contributing to peptic inflammation, ulceration, and cancer. A crucial step in the pathogenic sequence is when the bacterium first interacts with gastric tissue, an event that is poorly understood in vivo. We have shown that the luminal space adjacent to gastric epithelial damage is a microenvironment, and we hypothesized that this microenvironment might enhance H. pylori colonization. Inoculation with 106 H. pylori (wild-type Sydney Strain 1, SS1) significantly delayed healing of acetic-acid induced ulcers at Day 1, 7 and 30 post-inoculation, and wild-type SS1 preferentially colonized the ulcerated area compared to uninjured gastric tissue in the same animal at all time points. Gastric resident Lactobacillus spp. did not preferentially colonize ulcerated tissue. To determine whether bacterial motility and chemotaxis are important to ulcer healing and colonization, we analyzed isogenic H. pylori mutants defective in motility (ΔmotB) or chemotaxis (ΔcheY). ΔmotB (10(6)) failed to colonize ulcerated or healthy stomach tissue. ΔcheY (10(6)) colonized both tissues, but without preferential colonization of ulcerated tissue. However, ΔcheY did modestly delay ulcer healing, suggesting that chemotaxis is not required for this process. We used two-photon microscopy to induce microscopic epithelial lesions in vivo, and evaluated accumulation of fluorescently labeled H. pylori at gastric damage sites in the time frame of minutes instead of days. By 5 min after inducing damage, H. pylori SS1 preferentially accumulated at the site of damage and inhibited gastric epithelial restitution. H. pylori ΔcheY modestly accumulated at the gastric surface and inhibited restitution, but did not preferentially accumulate at the injury site. H. pylori ΔmotB neither accumulated at the surface nor inhibited restitution. We conclude that bacterial chemosensing and motility rapidly promote H. pylori colonization of injury sites, and thereby biases the injured tissue towards sustained gastric damage.

Bioenergetics during calvarial osteoblast differentiation reflect strain differences in bone mass.

PubMed

Guntur, Anyonya R; Le, Phuong T; Farber, Charles R; Rosen, Clifford J

2014-05-01

Osteoblastogenesis is the process by which mesenchymal stem cells differentiate into osteoblasts that synthesize collagen and mineralize matrix. The pace and magnitude of this process are determined by multiple genetic and environmental factors. Two inbred strains of mice, C3H/HeJ and C57BL/6J, exhibit differences in peak bone mass and bone formation. Although all the heritable factors that differ between these strains have not been elucidated, a recent F1 hybrid expression panel (C3H × B6) revealed major genotypic differences in osteoblastic genes related to cellular respiration and oxidative phosphorylation. Thus, we hypothesized that the metabolic rate of energy utilization by osteoblasts differed by strain and would ultimately contribute to differences in bone formation. In order to study the bioenergetic profile of osteoblasts, we measured oxygen consumption rates (OCR) and extracellular acidification rates (ECAR) first in a preosteoblastic cell line MC3T3-E1C4 and subsequently in primary calvarial osteoblasts from C3H and B6 mice at days 7, 14, and 21 of differentiation. During osteoblast differentiation in media containing ascorbic acid and β-glycerophosphate, all 3 cell types increased their oxygen consumption and extracellular acidification rates compared with the same cells grown in regular media. These increases are sustained throughout differentiation. Importantly, C3H calvarial osteoblasts had greater oxygen consumption rates than B6 consistent with their in vivo phenotype of higher bone formation. Interestingly, osteoblasts utilized both oxidative phosphorylation and glycolysis during the differentiation process although mature osteoblasts were more dependent on glycolysis at the 21-day time point than oxidative phosphorylation. Thus, determinants of oxygen consumption reflect strain differences in bone mass and provide the first evidence that during collagen synthesis osteoblasts use both glycolysis and oxidative phosphorylation to synthesize and mineralize matrix.

Bioenergetics During Calvarial Osteoblast Differentiation Reflect Strain Differences in Bone Mass

PubMed Central

Le, Phuong T.; Farber, Charles R.; Rosen, Clifford J.

2014-01-01

Osteoblastogenesis is the process by which mesenchymal stem cells differentiate into osteoblasts that synthesize collagen and mineralize matrix. The pace and magnitude of this process are determined by multiple genetic and environmental factors. Two inbred strains of mice, C3H/HeJ and C57BL/6J, exhibit differences in peak bone mass and bone formation. Although all the heritable factors that differ between these strains have not been elucidated, a recent F1 hybrid expression panel (C3H × B6) revealed major genotypic differences in osteoblastic genes related to cellular respiration and oxidative phosphorylation. Thus, we hypothesized that the metabolic rate of energy utilization by osteoblasts differed by strain and would ultimately contribute to differences in bone formation. In order to study the bioenergetic profile of osteoblasts, we measured oxygen consumption rates (OCR) and extracellular acidification rates (ECAR) first in a preosteoblastic cell line MC3T3-E1C4 and subsequently in primary calvarial osteoblasts from C3H and B6 mice at days 7, 14, and 21 of differentiation. During osteoblast differentiation in media containing ascorbic acid and β-glycerophosphate, all 3 cell types increased their oxygen consumption and extracellular acidification rates compared with the same cells grown in regular media. These increases are sustained throughout differentiation. Importantly, C3H calvarial osteoblasts had greater oxygen consumption rates than B6 consistent with their in vivo phenotype of higher bone formation. Interestingly, osteoblasts utilized both oxidative phosphorylation and glycolysis during the differentiation process although mature osteoblasts were more dependent on glycolysis at the 21-day time point than oxidative phosphorylation. Thus, determinants of oxygen consumption reflect strain differences in bone mass and provide the first evidence that during collagen synthesis osteoblasts use both glycolysis and oxidative phosphorylation to synthesize and mineralize matrix. PMID:24437492

Mesocortical dopamine depletion and anxiety-related behavior in the rat: sex and hemisphere differences.

PubMed

Sullivan, R M; Dufresne, M M; Siontas, D; Chehab, S; Townsend, J; Laplante, F

2014-10-03

The mesocortical dopamine (DA) system of the rat plays an important role in prefrontal cortex (PFC) regulation of stress and emotion and exhibits functional hemispheric asymmetry for such processing. Since few studies examine sex differences in this context, we compared the effects of left vs. right unilateral PFC DA depletion in males and females in several behavioral situations associated with anxiety or aversion. Adult rats received unilateral injections of 6-hydroxydopamine (6-OHDA) or vehicle in the ventromedial (vm) PFC. Behavioral tests included a predator odor burying test, elevated plus maze and sucrose consumption with simple taste aversion. Tissue analysis confirmed that vmPFCs injected with 6-OHDA were depleted of DA (75-85%) compared to controls. Burying behavior and sucrose consumption were affected only by left lesions, similarly in both sexes. However, risk assessment behaviors were affected by right lesions in opposite directions in males and females. Behaviors modified preferentially by the left cortex thus showed less evidence of sex differences than those modulated by the right. While mesocortical DA depletion effects are lateralized, the nature of these effects can vary with sex and specific behavior. Such findings may be clinically significant, given the large gender differences in the incidence of mood and anxiety disorders, which also show many lateralized prefrontal abnormalities. Copyright © 2014 Elsevier Inc. All rights reserved.

Induction of lactose transport in Escherichia coli during the absence of phospholipid synthesis.

PubMed Central

Weisberg, L J; Cronan, J E; Nunn, W D

1975-01-01

Induction of lactose transport and of beta-galactosidase synthesis was examined in two Escherichia coli strains that require exogenous glycerol for phospholipid synthesis and growth. No preferential inhibition of lactose transport induction was observed when phospholipid synthesis was restricted to 5 to 10% of the normal rate. We conclude that the lactose transport system does not require concurrent phospholipid synthesis for its functional assembly. PMID:1097412

Improvement in ethanol productivity of engineered E. coli strain SSY13 in defined medium via adaptive evolution.

PubMed

Jilani, Syed Bilal; Venigalla, Siva Sai Krishna; Mattam, Anu Jose; Dev, Chandra; Yazdani, Syed Shams

2017-09-01

E. coli has the ability to ferment both C5 and C6 sugars and produce mixture of acids along with small amount of ethanol. In our previous study, we reported the construction of an ethanologenic E. coli strain by modulating flux through the endogenous pathways. In the current study, we made further changes in the strain to make the overall process industry friendly; the changes being (1) removal of plasmid, (2) use of low-cost defined medium, and (3) improvement in consumption rate of both C5 and C6 sugars. We first constructed a plasmid-free strain SSY13 and passaged it on AM1-xylose minimal medium plate for 150 days. Further passaging was done for 56 days in liquid AM1 medium containing either glucose or xylose on alternate days. We observed an increase in specific growth rate and carbon utilization rate with increase in passage numbers until 42 days for both glucose and xylose. The 42nd day passaged strain SSK42 fermented 113 g/L xylose in AM1 minimal medium and produced 51.1 g/L ethanol in 72 h at 89% of maximum theoretical yield with ethanol productivity of 1.4 g/L/h during 24-48 h of fermentation. The ethanol titer, yield and productivity were 49, 40 and 36% higher, respectively, for SSK42 as compared to unevolved SSY13 strain.

Bilateral changes in forearm oxygen consumption at rest and after exercise in patients with unilateral repetitive strain injury: a case-control study.

PubMed

Brunnekreef, Jaap J J; Thijssen, Dick H J; Oosterhof, Jan; Hopman, Maria T E

2012-04-01

Case-control study. To investigate whether oxygen consumption and blood flow at rest and after exercise are lower in the affected arm of patients with repetitive strain injury (RSI) compared to controls, and lower in the healthy nonaffected forearm within patients with unilateral RSI. RSI is considered an upper extremity overuse injury. Despite the local presentation of complaints, RSI may be represented by systemic adaptations. Insight into the pathophysiology of RSI is important to better understand the development of RSI complaints and to develop effective treatment and prevention strategies. Twenty patients with unilateral RSI and 20 gender-matched control subjects participated in this study. Forearm muscle blood flow and oxygen consumption were measured using near-infrared spectroscopy at baseline and immediately after isometric handgrip exercises at 10%, 20%, and 40% of the individual maximal voluntary contraction. Unilateral RSI resulted in a lower oxygen consumption and blood flow in the affected forearm at baseline and lower oxygen consumption after incremental handgrip exercises compared to controls (P<.05). In addition, exercise-induced blood flow and oxygen consumption in the nonaffected forearm in patients with RSI were similarly reduced. Blood flow and oxygen consumption after exercise are similarly attenuated in the affected and nonaffected arms of patients with unilateral RSI. Our findings suggest that, despite the unilateral character in clinical symptoms, RSI demonstrates systemic adaptations in forearm blood flow and oxygen consumption at rest and after exercise.

Influence of yeast strain, priming solution and temperature on beer bottle conditioning.

PubMed

Marconi, Ombretta; Rossi, Serena; Galgano, Fernanda; Sileoni, Valeria; Perretti, Giuseppe

2016-09-01

Recently, there has been a significant increase in the number of microbreweries. Usually, craft beers are bottle conditioned; however, few studies have investigated beer refermentation. One of the objectives of this study was to evaluate the impacts of different experimental conditions, specifically yeast strain, priming solution and temperature, on the standard quality attributes, the volatile compounds and the sensory profile of the bottle-conditioned beer. The other aim was to monitor the evolution of volatile compounds and amino acids consumption throughout the refermentation process to check if it is possible to reduce the time necessary for bottle conditioning. The results indicate that the volatile profile was mainly influenced by the strain of yeast, and this may have obscured the possible impacts of the other parameters. Our results also confirm that the two yeast strains showed different metabolic activity, particularly with respect to esters production. Moreover, we found the Safbrew S-33® strain when primed with Siromix® and refermented at 30 °C yielded the fastest formation of higher alcohols while maintaining low production of off-flavours. These results suggest a formulation that may reduce the time needed for bottle conditioning without affecting the quality of the final beer which may simultaneously improve efficiency and economic profits. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Oxygen Consumption by Postfermentation Wine Yeast Lees: Factors Affecting Its Rate and Extent under Oenological Conditions

PubMed Central

Müller, Jonas; Schmidt, Dominik

2016-01-01

Summary Postfermentation wine yeast lees show antioxidant properties based on their ability to consume dissolved oxygen. The oxygen consumption capacity of suspended yeast lees obtained after fermentations with six commercial active dry yeast strains was investigated in model, white and red wines using fluorescence-based oxygen sensors operating in a nondestructive way. In model solution, the oxygen consumption rate of yeast lees was shown to depend on their amount, yeast strain, sulfur dioxide and temperature. It is slightly lower in red than in white wines. It is strongly decreased by current levels of free sulfur dioxide, thus excluding the complementary use of both as antioxidants in wine. However, in 25 randomly sampled white wines produced under commercial conditions, the rate and extent of oxygen consumption during the first six months of postfermentation had no significant correlation with any of these interacting factors, making it difficult to predict the actual antioxidant effect of yeast lees. In these wines, yeast lees consumed 0 to 47% of the dissolved oxygen. Although total oxygen consumption capacity of yeast lees is not a limiting factor under commercial winemaking conditions, their oxygen consumption proceeds at a limited rate that reduces but cannot totally prevent concomitant chemical oxidation of the wine. PMID:28115896

Oxygen Consumption by Postfermentation Wine Yeast Lees: Factors Affecting Its Rate and Extent under Oenological Conditions.

PubMed

Schneider, Volker; Müller, Jonas; Schmidt, Dominik

2016-12-01

Postfermentation wine yeast lees show antioxidant properties based on their ability to consume dissolved oxygen. The oxygen consumption capacity of suspended yeast lees obtained after fermentations with six commercial active dry yeast strains was investigated in model, white and red wines using fluorescence-based oxygen sensors operating in a nondestructive way. In model solution, the oxygen consumption rate of yeast lees was shown to depend on their amount, yeast strain, sulfur dioxide and temperature. It is slightly lower in red than in white wines. It is strongly decreased by current levels of free sulfur dioxide, thus excluding the complementary use of both as antioxidants in wine. However, in 25 randomly sampled white wines produced under commercial conditions, the rate and extent of oxygen consumption during the first six months of postfermentation had no significant correlation with any of these interacting factors, making it difficult to predict the actual antioxidant effect of yeast lees. In these wines, yeast lees consumed 0 to 47% of the dissolved oxygen. Although total oxygen consumption capacity of yeast lees is not a limiting factor under commercial winemaking conditions, their oxygen consumption proceeds at a limited rate that reduces but cannot totally prevent concomitant chemical oxidation of the wine.

Adaptation of the xylose fermenting yeast Saccharomyces cerevisiae F12 for improving ethanol production in different fed-batch SSF processes.

PubMed

Tomás-Pejó, E; Ballesteros, M; Oliva, J M; Olsson, L

2010-11-01

An efficient fermenting microorganism for bioethanol production from lignocellulose is highly tolerant to the inhibitors released during pretreatment and is able to ferment efficiently both glucose and xylose. In this study, directed evolution was employed to improve the xylose fermenting Saccharomyces cerevisiae F12 strain for bioethanol production at high substrate loading. Adapted and parental strains were compared with respect to xylose consumption and ethanol production. Adaptation led to an evolved strain more tolerant to the toxic compounds present in the medium. When using concentrated prehydrolysate from steam-pretreated wheat straw with high inhibitor concentration, an improvement of 65 and 20% in xylose consumption and final ethanol concentration, respectively, were achieved using the adapted strain. To address the need of high substrate loadings, fed-batch SSF experiments were performed and an ethanol concentration as high as 27.4 g/l (61% of the theoretical) was obtained with 11.25% (w/w) of water insoluble solids (WIS).

Phenotypic and metabolic traits of commercial Saccharomyces cerevisiae yeasts

PubMed Central

2014-01-01

Currently, pursuing yeast strains that display both a high potential fitness for alcoholic fermentation and a favorable impact on quality is a major goal in the alcoholic beverage industry. This considerable industrial interest has led to many studies characterizing the phenotypic and metabolic traits of commercial yeast populations. In this study, 20 Saccharomyces cerevisiae strains from different geographical origins exhibited high phenotypic diversity when their response to nine biotechnologically relevant conditions was examined. Next, the fermentation fitness and metabolic traits of eight selected strains with a unique phenotypic profile were evaluated in a high-sugar synthetic medium under two nitrogen regimes. Although the strains exhibited significant differences in nitrogen requirements and utilization rates, a direct relationship between nitrogen consumption, specific growth rate, cell biomass, cell viability, acetic acid and glycerol formation was only observed under high-nitrogen conditions. In contrast, the strains produced more succinic acid under the low-nitrogen regime, and a direct relationship with the final cell biomass was established. Glucose and fructose utilization patterns depended on both yeast strain and nitrogen availability. For low-nitrogen fermentation, three strains did not fully degrade the fructose. This study validates phenotypic and metabolic diversity among commercial wine yeasts and contributes new findings on the relationship between nitrogen availability, yeast cell growth and sugar utilization. We suggest that measuring nitrogen during the stationary growth phase is important because yeast cells fermentative activity is not exclusively related to population size, as previously assumed, but it is also related to the quantity of nitrogen consumed during this growth phase. PMID:24949272

Phenotypic and metabolic traits of commercial Saccharomyces cerevisiae yeasts.

PubMed

Barbosa, Catarina; Lage, Patrícia; Vilela, Alice; Mendes-Faia, Arlete; Mendes-Ferreira, Ana

2014-01-01

Currently, pursuing yeast strains that display both a high potential fitness for alcoholic fermentation and a favorable impact on quality is a major goal in the alcoholic beverage industry. This considerable industrial interest has led to many studies characterizing the phenotypic and metabolic traits of commercial yeast populations. In this study, 20 Saccharomyces cerevisiae strains from different geographical origins exhibited high phenotypic diversity when their response to nine biotechnologically relevant conditions was examined. Next, the fermentation fitness and metabolic traits of eight selected strains with a unique phenotypic profile were evaluated in a high-sugar synthetic medium under two nitrogen regimes. Although the strains exhibited significant differences in nitrogen requirements and utilization rates, a direct relationship between nitrogen consumption, specific growth rate, cell biomass, cell viability, acetic acid and glycerol formation was only observed under high-nitrogen conditions. In contrast, the strains produced more succinic acid under the low-nitrogen regime, and a direct relationship with the final cell biomass was established. Glucose and fructose utilization patterns depended on both yeast strain and nitrogen availability. For low-nitrogen fermentation, three strains did not fully degrade the fructose. This study validates phenotypic and metabolic diversity among commercial wine yeasts and contributes new findings on the relationship between nitrogen availability, yeast cell growth and sugar utilization. We suggest that measuring nitrogen during the stationary growth phase is important because yeast cells fermentative activity is not exclusively related to population size, as previously assumed, but it is also related to the quantity of nitrogen consumed during this growth phase.

Dehalogenation of chlorobenzenes, dichlorotoluenes, and tetrachloroethene by three Dehalobacter spp.

PubMed

Nelson, Jennifer L; Jiang, Jiandong; Zinder, Stephen H

2014-04-01

Three enrichment cultures containing Dehalobacter spp. were developed that dehalogenate each of the dichlorobenzene (DCB) isomers to monochlorobenzene (MCB), and the strains using 1,2-DCB (12DCB1) or 1,3-DCB (13DCB1) are now considered isolated, whereas the strain using 1,4-DCB (14DCB1) is considered highly enriched. In this study, we examined the dehalogenation capability of each strain to use chlorobenzenes with three or more chlorines, tetrachloroethene (PCE), or dichlorotoluene (DCT) isomers. Strain 12DCB1 preferentially dehalogenated singly flanked chlorines, but not doubly flanked or unflanked chlorines. It dehalogenated pentachlorobenzene to MCB with little buildup of intermediates. Strain 13DCB1, which could use either 1,3-DCB or 1,2-DCB, demonstrated the widest dehalogenation spectrum of electron acceptors tested, and dehalogenated every chlorobenzene isomer except 1,4-DCB. Notably, strain 13DCB1 dehalogenated the recalcitrant 1,3,5-trichlorobenzene isomer to MCB, and qPCR of 16S rRNA genes indicated that strain 13DCB1 grew. Strain 14DCB1 exhibited the narrowest range of substrate utilization, but was the only strain to dehalogenate para-substituted chlorines. Strains 12DCB1 and 13DCB1 dehalogenated PCE to cis-dichloroethene, and all strains dehalogenated 3,4-DCT to monochlorotoluene. These findings show that Dehalobacter spp., like Dehalococcoides spp., are versatile dehalogenators and should be considered when determining the fate of chlorinated organics at contaminated sites.

Discovery of a novel glucose metabolism in cancer: The role of endoplasmic reticulum beyond glycolysis and pentose phosphate shunt

PubMed Central

Marini, Cecilia; Ravera, Silvia; Buschiazzo, Ambra; Bianchi, Giovanna; Orengo, Anna Maria; Bruno, Silvia; Bottoni, Gianluca; Emionite, Laura; Pastorino, Fabio; Monteverde, Elena; Garaboldi, Lucia; Martella, Roberto; Salani, Barbara; Maggi, Davide; Ponzoni, Mirco; Fais, Franco; Raffaghello, Lizzia; Sambuceti, Gianmario

2016-01-01

Cancer metabolism is characterized by an accelerated glycolytic rate facing reduced activity of oxidative phosphorylation. This “Warburg effect” represents a standard to diagnose and monitor tumor aggressiveness with 18F-fluorodeoxyglucose whose uptake is currently regarded as an accurate index of total glucose consumption. Studying cancer metabolic response to respiratory chain inhibition by metformin, we repeatedly observed a reduction of tracer uptake facing a marked increase in glucose consumption. This puzzling discordance brought us to discover that 18F-fluorodeoxyglucose preferentially accumulates within endoplasmic reticulum by exploiting the catalytic function of hexose-6-phosphate-dehydrogenase. Silencing enzyme expression and activity decreased both tracer uptake and glucose consumption, caused severe energy depletion and decreased NADPH content without altering mitochondrial function. These data document the existence of an unknown glucose metabolism triggered by hexose-6-phosphate-dehydrogenase within endoplasmic reticulum of cancer cells. Besides its basic relevance, this finding can improve clinical cancer diagnosis and might represent potential target for therapy. PMID:27121192

Improving ethanol yield in acetate-reducing Saccharomyces cerevisiae by cofactor engineering of 6-phosphogluconate dehydrogenase and deletion of ALD6.

PubMed

Papapetridis, Ioannis; van Dijk, Marlous; Dobbe, Arthur P A; Metz, Benjamin; Pronk, Jack T; van Maris, Antonius J A

2016-04-26

Acetic acid, an inhibitor of sugar fermentation by yeast, is invariably present in lignocellulosic hydrolysates which are used or considered as feedstocks for yeast-based bioethanol production. Saccharomyces cerevisiae strains have been constructed, in which anaerobic reduction of acetic acid to ethanol replaces glycerol formation as a mechanism for reoxidizing NADH formed in biosynthesis. An increase in the amount of acetate that can be reduced to ethanol should further decrease acetic acid concentrations and enable higher ethanol yields in industrial processes based on lignocellulosic feedstocks. The stoichiometric requirement of acetate reduction for NADH implies that increased generation of NADH in cytosolic biosynthetic reactions should enhance acetate consumption. Replacement of the native NADP(+)-dependent 6-phosphogluconate dehydrogenase in S. cerevisiae by a prokaryotic NAD(+)-dependent enzyme resulted in increased cytosolic NADH formation, as demonstrated by a ca. 15% increase in the glycerol yield on glucose in anaerobic cultures. Additional deletion of ALD6, which encodes an NADP(+)-dependent acetaldehyde dehydrogenase, led to a 39% increase in the glycerol yield compared to a non-engineered strain. Subsequent replacement of glycerol formation by an acetate reduction pathway resulted in a 44% increase of acetate consumption per amount of biomass formed, as compared to an engineered, acetate-reducing strain that expressed the native 6-phosphogluconate dehydrogenase and ALD6. Compared to a non-acetate reducing reference strain under the same conditions, this resulted in a ca. 13% increase in the ethanol yield on glucose. The combination of NAD(+)-dependent 6-phosphogluconate dehydrogenase expression and deletion of ALD6 resulted in a marked increase in the amount of acetate that was consumed in these proof-of-principle experiments, and this concept is ready for further testing in industrial strains as well as in hydrolysates. Altering the cofactor specificity of the oxidative branch of the pentose-phosphate pathway in S. cerevisiae can also be used to increase glycerol production in wine fermentation and to improve NADH generation and/or generation of precursors derived from the pentose-phosphate pathway in other industrial applications of this yeast.

Microbial characterization of probiotics–Advisory report of the Working Group “8651 Probiotics” of the Belgian Superior Health Council (SHC)

PubMed Central

Huys, Geert; Botteldoorn, Nadine; Delvigne, Frank; Vuyst, Luc De; Heyndrickx, Marc; Pot, Bruno; Dubois, Jean-Jacques; Daube, Georges

2013-01-01

When ingested in sufficient numbers, probiotics are expected to confer one or more proven health benefits on the consumer. Theoretically, the effectiveness of a probiotic food product is the sum of its microbial quality and its functional potential. Whereas the latter may vary much with the body (target) site, delivery mode, human target population, and health benefit envisaged microbial assessment of the probiotic product quality is more straightforward. The range of stakeholders that need to be informed on probiotic quality assessments is extremely broad, including academics, food and biotherapeutic industries, healthcare professionals, competent authorities, consumers, and professional press. In view of the rapidly expanding knowledge on this subject, the Belgian Superior Health Council installed Working Group “8651 Probiotics” to review the state of knowledge regarding the methodologies that make it possible to characterize strains and products with purported probiotic activity. This advisory report covers three main steps in the microbial quality assessment process, i.e. (i) correct species identification and strain-specific typing of bacterial and yeast strains used in probiotic applications, (ii) safety assessment of probiotic strains used for human consumption, and (iii) quality of the final probiotic product in terms of its microbial composition, concentration, stability, authenticity, and labeling. PMID:23801655

Inactivation of the PTS as a Strategy to Engineer the Production of Aromatic Metabolites in Escherichia coli.

PubMed

Carmona, Susy Beatriz; Moreno, Fabián; Bolívar, Francisco; Gosset, Guillermo; Escalante, Adelfo

2015-01-01

Laboratory and industrial cultures of Escherichia coli employ media containing glucose which is mainly transported and phosphorylated by the phosphotransferase system (PTS). In these strains, 50% of the phosphoenolpyruvate (PEP), which results from the catabolism of transported glucose, is used as a phosphate donor for its phosphorylation and translocation by the PTS. This characteristic of the PTS limits the production of industrial biocommodities that have PEP as a precursor. Furthermore, when E. coli is exposed to carbohydrate mixtures, the PTS prevents expression of catabolic and non-PTS transport genes by carbon catabolite repression and inducer exclusion. In this contribution, we discuss the main strategies developed to overcome these potentially limiting effects in production strains. These strategies include adaptive laboratory evolution selection of PTS(-) Glc(+) mutants, followed by the generation of strains that recover their ability to grow with glucose as a carbon source while allowing the simultaneous consumption of more than one carbon source. We discuss the benefits of using alternative glucose transport systems and describe the application of these strategies to E. coli strains with specific genetic modifications in target pathways. These efforts have resulted in significant improvements in the production of diverse biocommodities, including aromatic metabolites, biofuels and organic acids. © 2015 S. Karger AG, Basel.

Toluene degradation by Cupriavidus metallidurans CH34 in nitrate-reducing conditions and in Bioelectrochemical Systems.

PubMed

Tofalos, Anna Espinoza; Daghio, Matteo; González, Myriam; Papacchini, Maddalena; Franzetti, Andrea; Seeger, Michael

2018-05-16

Bioelectrochemical remediation of hydrocarbons is a technology that exploits the ability of specific microorganisms to use as electron acceptor an electrode, thus potentially lowering the operational costs related to classical bioremediation. Several well-characterized hydrocarbonoclastic strains might be electroactive, thus their biodegradation performances in Bioelectrochemical Systems should be studied. Cupriavidus metallidurans CH34 is a model metal-resistant strain whose capacity to degrade benzene aerobically has recently been described. In this study, toluene degradation under anaerobic conditions and the exoelectrogenic capacity of Cupriavidus metallidurans CH34 were determined. Strain CH34 was grown anaerobically with toluene as sole carbon source in sealed serum bottles and then inoculated in a Microbial Electrolysis Cell (MEC) to assess its exoelectrogenic capacity. It was demonstrated for the first time that strain CH34 is able to degrade toluene under nitrate-reducing conditions (up to 45 mgtoluene/L were removed within 17 days, corresponding to 73% of toluene amended). Nitrate consumption and cellular growth were observed during toluene removal. In the MEC, toluene degradation was linked to current production, showing current peaks after every toluene addition (maximum current density 48 mA/m2). Coulombic efficiency of the toluene biodegradation process increased with time, from 11% (first batch cycle), up to 77% (last batch cycle).

Mechanical signaling in the development of postmenopausal osteoporosis

NASA Technical Reports Server (NTRS)

Turner, R. T.

1999-01-01

Estrogen deficiency results in increased bone turnover and net bone loss in rats as well as humans. The respective roles of bone turnover and mechanical strain in mediating estrogen deficiency-induced cancellous bone loss were investigated in ovariectomized rats. Ovariectomy resulted in increased bone turnover in long bones. However, cancellous bone was preferentially lost in the metaphysis, a site that experiences low strain energy during normal physical activity. No bone loss was observed in the epiphysis, a site experiencing higher strain energy, despite a similar increase in bone turnover. The role of mechanical strain in maintaining bone balance was investigated by altering the strain history. Mechanical strain was increased or decreased in long bones of ovariectomized rats by treadmill exercise or functional unloading, respectively. Increasing mechanical loading reduced bone loss in the metaphysis. In contrast, decreasing weight bearing accentuated bone loss in the metaphysis and resulted in bone loss in the epiphysis. Finally, administration of estrogen to ovariectomized rats reduced bone loss in unloaded limbs and prevented bone loss in the loaded limbs. These results suggest that estrogen alters the mechanosensory (mechanostat) set point for skeletal adaptation, effectively reducing the minimum strain energy levels at which bone is added. Additionally, these studies suggest that physical activity as well as endocrine status play an important role in maintenance of the female skeleton during aging.

A Molecular Basis for Bifidobacterial Enrichment in the Infant Gastrointestinal Tract123

PubMed Central

Garrido, Daniel; Barile, Daniela; Mills, David A.

2012-01-01

Bifidobacteria are commonly used as probiotics in dairy foods. Select bifidobacterial species are also early colonizers of the breast-fed infant colon; however, the mechanism for this enrichment is unclear. We previously showed that Bifidobacterium longum subsp. infantis is a prototypical bifidobacterial species that can readily utilize human milk oligosaccharides as the sole carbon source. MS-based glycoprofiling has revealed that numerous B. infantis strains preferentially consume small mass oligosaccharides, abundant in human milks. Genome sequencing revealed that B. infantis possesses a bias toward genes required to use mammalian-derived carbohydrates. Many of these genomic features encode enzymes that are active on milk oligosaccharides including a novel 40-kb region dedicated to oligosaccharide utilization. Biochemical and molecular characterization of the encoded glycosidases and transport proteins has further resolved the mechanism by which B. infantis selectively imports and catabolizes milk oligosaccharides. Expression studies indicate that many of these key functions are only induced during growth on milk oligosaccharides and not expressed during growth on other prebiotics. Analysis of numerous B. infantis isolates has confirmed that these genomic features are common among the B. infantis subspecies and likely constitute a competitive colonization strategy used by these unique bifidobacteria. By detailed characterization of the molecular mechanisms responsible, these studies provide a conceptual framework for bifidobacterial persistence and host interaction in the infant gastrointestinal tract mediated in part through consumption of human milk oligosaccharides. PMID:22585920

Effect of Ventilated Caging on Water Intake and Loss in 4 Strains of Laboratory Mice

PubMed Central

Nicolaus, Mackenzie L; Bergdall, Valerie K; Davis, Ian C; Hickman-Davis, Judy M

2016-01-01

Food availability, temperature, humidity, strain, and caging type all affect water consumption by mice. Measurement of transepidermal water loss (TEWL) is a new technique for the quantification of water turnover in mice. To understand water turnover in common strains of adult mice, male and female SCID, SKH, C57BL/6, and FVB mice were housed in same-sex groups of 5 animals in static cages or IVC. Body weight, TEWL, urine osmolality, and water consumption of mice and intracage temperature and humidity were measured every 48 h for comparison. Static cages were monitored for 7 d and IVC for 14 d before cage change. Female SCID, FVB, and C57 mice drank less water than did their male counterparts. Male and female SCID, SKH, and FVB mice in IVC drank less water and had higher urine osmolality than did those in static cages. In SCID and SKH mice, TEWL paralleled water consumption. C57 mice in static cages drank less water, had lower urine osmolality, and had less TEWL than did those in IVC. Temperature and humidity within the cage was higher than the macroenvironmental levels for all housing conditions, mouse strains, and sexes. Temperatures within IVC ranged from 76.6 to 81.4 °F compared with 69 ± 0.4 °F in the room. Humidity within IVC ranged from 68% to 79% compared with 27.o% ± 2.7% within the room. These data demonstrate that mouse strain and housing conditions significantly influence water balance and indicate that macroenvironmental measurements do not always reflect the intracage environment. PMID:27657706

Metabolic analysis of the synthesis of high levels of intracellular human SOD in Saccharomyces cerevisiae rhSOD 2060 411 SGA122.

PubMed

Gonzalez, Ramon; Andrews, Barbara A; Molitor, Julia; Asenjo, Juan A

2003-04-20

The synthesis of human superoxide dismutase (SOD) in batch cultures of a Saccharomyces cerevisiae strain using a glucose-limited minimal medium was studied through metabolic flux analysis. A stoichiometric model was built, which included 78 reactions, according to metabolic pathways operative in these strains during respirofermentative and oxidative metabolism. It allowed calculation of the distribution of metabolic fluxes during diauxic growth on glucose and ethanol. Fermentation profiles and metabolic fluxes were analyzed at different phases of diauxic growth for the recombinant strain (P+) and for its wild type (P-). The synthesis of SOD by the strain P+ resulted in a decrease in specific growth rate of 34 and 54% (growth on glucose and ethanol respectively) in comparison to the wild type. Both strains exhibited similar flux of glucose consumption and ethanol synthesis but important differences in carbon distribution with biomass/substrate yields and ATP production 50% higher in P-. A higher contribution of fermentative metabolism, with 64% of the energy produced at the phosphorylation level, was observed during SOD production. The flux of precursors to amino acids and nucleotides was higher in the recombinant strain, in agreement with the higher total RNA and protein levels. Lower specific growth rates in strain P+ appear to be related to the decrease in the rate of synthesis of nonrecombinant protein, as well as a decrease in the activities of the pentose phosphate (PP) pathway and TCA cycle. A very different way of entry into the stationary phase was observed for each strain: in the wild-type strain most metabolic fluxes decreased and fluxes related to energy reserve synthesis increased, while in the P+ strain the flux of 22 reactions (including PP pathway and amino acids biosynthesis) related to SOD production increased their fluxes. Changes in SOD production rates at different physiological states appear to be related to the differences in building blocks availability between respirofermentative and oxidative metabolism. Using the present expression system, ideal conditions for SOD synthesis are represented by either active growth during respirofermentative metabolism or transition from a growing to a nongrowing state. An increase in SOD flux could be achieved using an expression system nonassociated to growth and potentially eliminating part of the metabolic burden. Copyright 2003 Wiley Periodicals, Inc.

Soil, Water, Plants and Preferred Flow in All Directions: A Biosphere-2 Experiment

NASA Astrophysics Data System (ADS)

McDonnell, J.; Evaristo, J. A.; Kim, M.; Van Haren, J. L. M.; Pangle, L. A.; Harman, C. J.; Troch, P. A. A.

2016-12-01

Measuring, understanding and predicting preferential flow in the critical zone is impossibly difficult, but we must try. While past work has focused on specific features of preferential flow pathways and model parameterizations, the resultant effect of preferential flow is often difficult to detect because we do not know the boundary conditions of our flow domain. Here we take a holistic view of preferential flow at the ecosystem level. We present new results from the tropical rainforest biome at Biosphere 2. We test the null hypothesis that the ecohydrological system is well mixed and that water forming groundwater recharge and plant transpiration is from a common pool. Our specific research question is what is the nature of preferential flow and partitioning of groundwater recharge, soil water recharge, and transpiration water after rainfall events? We performed a 10-week drought experiment and then added 66 mm of labelled rainfall with 152‰ deuterium (D), distributed over four events (mean 16.5 mm per event). This was followed by a total of 87 mm of rainfall (-60‰ D) distributed over 13 events that were spaced every 2-3 days. Our results show that flow in all ecohydrological domains (soil water, groundwater recharge and plant transpiration) was preferential. With known boundary conditions, we found that groundwater recharge was 3-8 times younger ( 8 days) than transpired water (range 24-64 days). The "age" of transpired water showed strong dependence on species and was intimately linked to driving force (difference between soil matric potential and midday leaf water potential). These results suggest that preferential flow in the critical zone is one whereby transpiration is strongly species-dependent, and groundwater recharge is controlled by inherent subsurface heterogeneity. The marked difference in the ages associated with these two fluxes supports the concept of ecohydrological separation—in this case, in a `time-based' context.

Performance of several Saccharomyces strains for the alcoholic fermentation of sugar-sweetened high-strength wastewaters: Comparative analysis and kinetic modelling.

PubMed

Comelli, Raúl N; Seluy, Lisandro G; Isla, Miguel A

2016-12-25

This work focuses on the performance of ten commercial Saccharomyces yeast strains in the batch alcoholic fermentation of sugars contained in selected industrial wastewaters from the soft drink industry. Fermentation has been applied successfully to treat these effluents prior to their disposal. Although many strains were investigated, similar behaviour was observed between all of the Saccharomyces strains tested. When media were inoculated with 2gL -1 of yeast, all strains were able to completely consume the available sugars in less than 14h. Thus, any of the strains studied in this work could be used in non-conventional wastewater treatment processes based on alcoholic fermentation. However, ethanol production varied between strains, and these differences could be significant from a production point of view. Saccharomyces bayanus produced the most ethanol, with a mean yield of 0.44g ethanol g sugarconsumed -1 and an ethanol specific production rate of 5.96g ethanol (Lh) -1 . As the assayed soft drinks wastewaters contain about 105g sugar /L of fermentable sugars, the concentration of ethanol achieved after the fermentations process was 46.2g ethanol /L. A rigorous kinetic modelling methodology was used to model the Saccharomyces bayanus fermentation process. The kinetic model included coupled mass balances and a minimal number of parameters. A simple unstructured model based on the Andrews equation (substrate inhibition) was developed. This model satisfactorily described biomass growth, sugar consumption and bioethanol production. In addition to providing insights into the fermentative performance of potentially relevant strains, this work can facilitate the design of large-scale ethanol production processes that use wastewaters from the sugar-sweetened beverage industry as feedstock. Copyright © 2016 Elsevier B.V. All rights reserved.

Genetic diversity of clinical and environmental Vibrio parahaemolyticus strains from the Pacific Northwest.

PubMed

Paranjpye, Rohinee; Hamel, Owen S; Stojanovski, Asta; Liermann, Martin

2012-12-01

Since 1997, cases of Vibrio parahaemolyticus-related gastroenteritis from the consumption of raw oysters harvested in Washington State have been higher than historical levels. These cases have shown little or no correlation with concentrations of potentially pathogenic V. parahaemolyticus (positive for the thermostable direct hemolysin gene, tdh) in oysters, although significant concentrations of tdh(+) V. parahaemolyticus strains were isolated from shellfish-growing areas in the Pacific Northwest (PNW). We compared clinical and environmental strains isolated from the PNW to those from other geographic regions within the United States and Asia for the presence of virulence-associated genes, including the thermostable direct hemolysin (tdh), the thermostable-related hemolysin (trh), urease (ureR), the pandemic group specific markers orf8 and toxRS, and genes encoding both type 3 secretion systems (T3SS1 and T3SS2). The majority of clinical strains from the PNW were positive for tdh, trh, and ureR genes, while a significant proportion of environmental isolates were tdh(+) but trh negative. Hierarchical clustering grouped the majority of these clinical isolates into a cluster distinct from that including the pandemic strain RIMD2210633, clinical isolates from other geographical regions, and tdh(+), trh-negative environmental isolates from the PNW. We detected T3SS2-related genes (T3SS2β) in environmental strains that were tdh and trh negative. The presence of significant concentrations of tdh(+), trh-negative environmental strains in the PNW that have not been responsible for illness and T3SS2β in tdh- and trh-negative strains emphasizes the diversity in this species and the need to identify additional virulence markers for this bacterium to improve risk assessment tools for the detection of this pathogen.

Unraveling the Nature of Active Sites in Ethanol Electro-oxidation by Site-Specific Marking of a Pt Catalyst with Isotope-Labeled 13CO.

PubMed

Farias, Manuel J S; Cheuquepán, William; Tanaka, Auro A; Feliu, Juan M

2018-03-15

This works deals with the identification of preferential site-specific activation at a model Pt surface during a multiproduct reaction. The (110)-type steps of a Pt(332) surface were selectively marked by attaching isotope-labeled 13 CO molecules to them, and ethanol oxidation was probed by in situ Foureir transfrom infrared spectroscopy in order to precisely determine the specific sites at which CO 2 , acetic acid, and acetaldehyde were preferentially formed. The (110) steps were active for splitting the C-C bond, but unexpectedly, we provide evidence that the pathway of CO 2 formation was preferentially activated at (111) terraces, rather than at (110) steps. Acetaldehyde was formed at (111) terraces at potentials comparable to those for CO 2 formation also at (111) terraces, while the acetic acid formation pathway became active only when the (110) steps were released by the oxidation of adsorbed 13 CO, at potentials higher than for the formation of CO 2 at (111) terraces of the stepped surface.

Traffic-aware energy saving scheme with modularization supporting in TWDM-PON

NASA Astrophysics Data System (ADS)

Xiong, Yu; Sun, Peng; Liu, Chuanbo; Guan, Jianjun

2017-01-01

Time and wavelength division multiplexed passive optical network (TWDM-PON) is considered to be a primary solution for next-generation passive optical network stage 2 (NG-PON2). Due to the feature of multi-wavelength transmission of TWDM-PON, some of the transmitters/receivers at the optical line terminal (OLT) could be shut down to reduce the energy consumption. Therefore, a novel scheme called traffic-aware energy saving scheme with modularization supporting is proposed. Through establishing the modular energy consumption model of OLT, the wavelength transmitters/receivers at OLT could be switched on or shut down adaptively depending on sensing the status of network traffic load, thus the energy consumption of OLT will be effectively reduced. Furthermore, exploring the technology of optical network unit (ONU) modularization, each module of ONU could be switched to sleep or active mode independently in order to reduce the energy consumption of ONU. Simultaneously, the polling sequence of ONU could be changed dynamically via sensing the packet arrival time. In order to guarantee the delay performance of network traffic, the sub-cycle division strategy is designed to transmit the real-time traffic preferentially. Finally, simulation results verify that the proposed scheme is able to reduce the energy consumption of the network while maintaining the traffic delay performance.

Centromere strength provides the cell biological basis for meiotic drive and karyotype evolution in mice.

PubMed

Chmátal, Lukáš; Gabriel, Sofia I; Mitsainas, George P; Martínez-Vargas, Jessica; Ventura, Jacint; Searle, Jeremy B; Schultz, Richard M; Lampson, Michael A

2014-10-06

Mammalian karyotypes (number and structure of chromosomes) can vary dramatically over short evolutionary time frames. There are examples of massive karyotype conversion, from mostly telocentric (centromere terminal) to mostly metacentric (centromere internal), in 10(2)-10(5) years. These changes typically reflect rapid fixation of Robertsonian (Rb) fusions, a common chromosomal rearrangement that joins two telocentric chromosomes at their centromeres to create one metacentric. Fixation of Rb fusions can be explained by meiotic drive: biased chromosome segregation during female meiosis in violation of Mendel's first law. However, there is no mechanistic explanation of why fusions would preferentially segregate to the egg in some populations, leading to fixation and karyotype change, while other populations preferentially eliminate the fusions and maintain a telocentric karyotype. Here we show, using both laboratory models and wild mice, that differences in centromere strength predict the direction of drive. Stronger centromeres, manifested by increased kinetochore protein levels and altered interactions with spindle microtubules, are preferentially retained in the egg. We find that fusions preferentially segregate to the polar body in laboratory mouse strains when the fusion centromeres are weaker than those of telocentrics. Conversely, fusion centromeres are stronger relative to telocentrics in natural house mouse populations that have changed karyotype by accumulating metacentric fusions. Our findings suggest that natural variation in centromere strength explains how the direction of drive can switch between populations. They also provide a cell biological basis of centromere drive and karyotype evolution. Copyright © 2014 Elsevier Ltd. All rights reserved.

Molecular Characterization of the Elaeis guineensis Medium-Chain Fatty Acid Diacylglycerol Acyltransferase DGAT1-1 by Heterologous Expression in Yarrowia lipolytica.

PubMed

Aymé, Laure; Jolivet, Pascale; Nicaud, Jean-Marc; Chardot, Thierry

2015-01-01

Diacylglycerol acyltransferases (DGAT) are involved in the acylation of sn-1,2-diacylglycerol. Palm kernel oil, extracted from Elaeis guineensis (oil palm) seeds, has a high content of medium-chain fatty acids mainly lauric acid (C12:0). A putative E. guineensis diacylglycerol acyltransferase gene (EgDGAT1-1) is expressed at the onset of lauric acid accumulation in the seed endosperm suggesting that it is a determinant of medium-chain triacylglycerol storage. To test this hypothesis, we thoroughly characterized EgDGAT1-1 activity through functional complementation of a Yarrowia lipolytica mutant strain devoid of neutral lipids. EgDGAT1-1 expression is sufficient to restore triacylglycerol accumulation in neosynthesized lipid droplets. A comparative functional study with Arabidopsis thaliana DGAT1 highlighted contrasting substrate specificities when the recombinant yeast was cultured in lauric acid supplemented medium. The EgDGAT1-1 expressing strain preferentially accumulated medium-chain triacylglycerols whereas AtDGAT1 expression induced long-chain triacylglycerol storage in Y. lipolytica. EgDGAT1-1 localized to the endoplasmic reticulum where TAG biosynthesis takes place. Reestablishing neutral lipid accumulation in the Y. lipolytica mutant strain did not induce major reorganization of the yeast microsomal proteome. Overall, our findings demonstrate that EgDGAT1-1 is an endoplasmic reticulum DGAT with preference for medium-chain fatty acid substrates, in line with its physiological role in palm kernel. The characterized EgDGAT1-1 could be used to promote medium-chain triacylglycerol accumulation in microbial-produced oil for industrial chemicals and cosmetics.

Molecular Characterization of the Elaeis guineensis Medium-Chain Fatty Acid Diacylglycerol Acyltransferase DGAT1-1 by Heterologous Expression in Yarrowia lipolytica

PubMed Central

Aymé, Laure; Jolivet, Pascale; Nicaud, Jean-Marc; Chardot, Thierry

2015-01-01

Diacylglycerol acyltransferases (DGAT) are involved in the acylation of sn-1,2-diacylglycerol. Palm kernel oil, extracted from Elaeis guineensis (oil palm) seeds, has a high content of medium-chain fatty acids mainly lauric acid (C12:0). A putative E. guineensis diacylglycerol acyltransferase gene (EgDGAT1-1) is expressed at the onset of lauric acid accumulation in the seed endosperm suggesting that it is a determinant of medium-chain triacylglycerol storage. To test this hypothesis, we thoroughly characterized EgDGAT1-1 activity through functional complementation of a Yarrowia lipolytica mutant strain devoid of neutral lipids. EgDGAT1-1 expression is sufficient to restore triacylglycerol accumulation in neosynthesized lipid droplets. A comparative functional study with Arabidopsis thaliana DGAT1 highlighted contrasting substrate specificities when the recombinant yeast was cultured in lauric acid supplemented medium. The EgDGAT1-1 expressing strain preferentially accumulated medium-chain triacylglycerols whereas AtDGAT1 expression induced long-chain triacylglycerol storage in Y. lipolytica. EgDGAT1-1 localized to the endoplasmic reticulum where TAG biosynthesis takes place. Reestablishing neutral lipid accumulation in the Y. lipolytica mutant strain did not induce major reorganization of the yeast microsomal proteome. Overall, our findings demonstrate that EgDGAT1-1 is an endoplasmic reticulum DGAT with preference for medium-chain fatty acid substrates, in line with its physiological role in palm kernel. The characterized EgDGAT1-1 could be used to promote medium-chain triacylglycerol accumulation in microbial-produced oil for industrial chemicals and cosmetics. PMID:26581109

Determinants and patterns of soft drink consumption in young adults: a qualitative analysis.

PubMed

Hattersley, Libby; Irwin, Melissa; King, Lesley; Allman-Farinelli, Margaret

2009-10-01

To explore knowledge, attitudes and behaviours regarding caloric soft drinks in a group of young adults attending university and to identify opportunities for a health promotion intervention aimed at reducing consumption. In-depth, semi-structured focus groups segmented by gender. Sydney, Australia. Undergraduate University of Sydney students aged 18-30 years (n 35). Social and environmental cues, intrinsic qualities of beverages and personal health beliefs were identified as important influences on consumption. Social cues included settings in which alcohol is usually consumed, socialising with friends, and family influences. Environmental cues included purchasing of fast foods, and ready availability, preferential pricing and promotion of caloric beverages. Reinforcing intrinsic qualities of caloric soft drinks included taste, sugar and caffeine content, and their association with treats and rewards. Major gender differences as well as variations in individual readiness for behaviour change were observed. Raising awareness of the sugar content of various beverages and the potential health impacts associated with their consumption was considered important. The findings provide new insights with important implications for policy and practice, and suggest that there is considerable scope for promoting awareness in this group. Carefully designed social marketing campaigns highlighting the health issues and addressing social and environmental cues relating to caloric soft drink consumption are required. There is a need for gender-differentiated intervention programmes which are both informational and appealing to young adults. Further research is warranted, particularly to investigate beverage consumption relating to fast-food meal deals and young adults' consumption patterns in more depth.

Immunization of lambs with the S48 strain of Toxoplasma gondii reduces tissue cyst burden following oral challenge with a complete strain of the parasite.

PubMed

Katzer, Frank; Canton, German; Burrells, Alison; Palarea-Albaladejo, Javier; Horton, Ben; Bartley, Paul M; Pang, Yvonne; Chianini, Francesca; Innes, Elisabeth A; Benavides, Julio

2014-09-15

This study evaluates the influence of immunizing lambs with the incomplete S48 strain of Toxoplasma gondii, on parasite dissemination following a live oral challenge with a complete strain of T. gondii (M4). Lambs were culled at 14, 28 and 42 days post challenge. Parasite DNA was detected at significantly (p<0.0001) lower levels in samples from the vaccinated/challenged group (0% in heart and 5.9% in skeletal muscles), when compared to the non-vaccinated/challenged animals (75% heart, 87.9% skeletal muscle). S48 T. gondii DNA was found in muscle or lymph nodes until 42 days post infection, suggesting that parasite DNA or tachyzoites could persist longer after immunization than previously thought. Non-vaccinated/challenged animals showed more frequent lesions in muscles and central nervous system than the vaccinated animals. These results demonstrate that vaccination of lambs with the incomplete S48 T. gondii strain, can protect against establishment of tissue cysts following challenge with a complete strain of T. gondii. Consumption of undercooked meat containing T. gondii cysts is a major route of transmission to people, therefore vaccination of food animals may improve the safety of meat for human consumption. Copyright © 2014 Elsevier B.V. All rights reserved.

Attenuated and Replication-Competent Vaccinia Virus Strains M65 and M101 with Distinct Biology and Immunogenicity as Potential Vaccine Candidates against Pathogens

PubMed Central

Sánchez-Sampedro, Lucas; Gómez, Carmen Elena; Mejías-Pérez, Ernesto; Pérez-Jiménez, Eva; Oliveros, Juan Carlos

2013-01-01

Replication-competent poxvirus vectors with an attenuation phenotype and with a high immunogenic capacity of the foreign expressed antigen are being pursued as novel vaccine vectors against different pathogens. In this investigation, we have examined the replication and immunogenic characteristics of two vaccinia virus (VACV) mutants, M65 and M101. These mutants were generated after 65 and 101 serial passages of persistently infected Friend erythroleukemia (FEL) cells. In cultured cells of different origins, the mutants are replication competent and have growth kinetics similar to or slightly reduced in comparison with those of the parental Western Reserve (WR) virus strain. In normal and immune-suppressed infected mice, the mutants showed different levels of attenuation and pathogenicity in comparison with WR and modified vaccinia Ankara (MVA) strains. Wide genome analysis after deep sequencing revealed selected genomic deletions and mutations in a number of viral open reading frames (ORFs). Mice immunized in a DNA prime/mutant boost regimen with viral vectors expressing the LACK (Leishmania homologue for receptors of activated C kinase) antigen of Leishmania infantum showed protection or a delay in the onset of cutaneous leishmaniasis. Protection was similar to that triggered by MVA-LACK. In immunized mice, both polyfunctional CD4+ and CD8+ T cells with an effector memory phenotype were activated by the two mutants, but the DNA-LACK/M65-LACK protocol preferentially induced CD4+ whereas DNA-LACK/M101-LACK preferentially induced CD8+ T cell responses. Altogether, our findings showed the adaptive changes of the WR genome during long-term virus-host cell interaction and how the replication competency of M65 and M101 mutants confers distinct biological properties and immunogenicity in mice compared to those of the MVA strain. These mutants could have applicability for understanding VACV biology and as potential vaccine vectors against pathogens and tumors. PMID:23596295

Oxonitriles: a grignard addition-acylation route to enamides.

PubMed

Fleming, Fraser F; Wei, Guoqing; Zhang, Zhiyu; Steward, Omar W

2006-10-12

[reaction: see text] Sequential addition of three different Grignard reagents and pivaloyl chloride to 3-oxo-1-cyclohexene-1-carbonitrile installs four new bonds to generate a diverse array of cyclic enamides. Remarkably, formation of the C-magnesiated nitrile intermediate is followed by preferential acylation by pivaloyl chloride rather than consumption by an in situ Grignard reagent. Rapid N-acylation of the C-magnesiated nitrile generates an acyl ketenimine that reacts readily with Grignard reagents or a trialkylzincate, effectively assembling highly substituted, cyclic enamides.

Oxonitriles: A Grignard Addition-Acylation Route to Enamides

PubMed Central

Wei, Guoqing; Zhang, Zhiyu; Steward, Omar W.

2008-01-01

Sequential addition of three different Grignard reagents and pivaloyl chloride to 3-oxo-1-cyclohexene-1-carbonitrile installs four new bonds to generate a diverse array of cyclic enamides. Remarkably, formation of the C-magnesiated nitrile intermediate is followed by preferential acylation by pivaloyl chloride rather than consumption by in situ Grignard reagent. Rapid N-acylation of the C-magnesiated nitrile generates an acyl ketenimine that reacts readily with Grignard reagents, or a trialkyl zincate, effectively assembling highly substituted, cyclic enamides. PMID:17020332

Diversity and Ecophysiology of New Isolates of Extremely Acidophilic CS2-Converting Acidithiobacillus Strains

PubMed Central

Smeulders, Marjan J.; Pol, Arjan; Zandvoort, Marcel H.; Jetten, Mike S. M.

2013-01-01

Biofiltration of industrial carbon disulfide (CS2)-contaminated waste air streams results in the acidification of biofilters and therefore reduced performance, high water use, and increased costs. To address these issues, we isolated 16 extremely acidophilic CS2-converting Acidithiobacillus thiooxidans strains that tolerated up to 6% (vol/vol) sulfuric acid. The ecophysiological properties of five selected strains (2Bp, Sts 4-3, S1p, G8, and BBW1) were compared. These five strains had pH optima between 1 (2Bp) and 2 (S1p). Their affinities for CS2 ranged between 80 (G8) and 130 (2Bp) μM. Strains S1p, G8, and BBW1 had more hydrophobic cell surfaces and produced less extracellular polymeric substance than did strains 2Bp and Sts 4-3. All five strains converted about 80% of the S added as CS2 to S0 when CS2 was supplied in excess. The rate of S0 consumption varied between 7 (Sts 4-3) and 63 (S1p) nmol O2 min−1 ml culture−1. Low S0 consumption rates correlated partly with low levels of cell attachment to externally produced S0 globules. During chemostat growth, the relative amount of CS2 hydrolase in the cell increased with decreasing growth rates. This resulted in more S0 accumulation during CS2 overloads at low growth rates. Intermittent interruptions of the CS2 supply affected all five strains. Strains S1p, G8, and BBW1 recovered from 24 h of starvation within 4 h, and strains 2Bp and Sts 4-3 recovered within 24 h after CS2 was resupplied. We recommend the use of mixtures of Acidithiobacillus strains in industrial biofilters. PMID:23995926

The complete annotated genome sequences of three Campylobacter jejuni strains isolated from naturally colonized, farm raised chickens

USDA-ARS?s Scientific Manuscript database

Campylobacter jejuni is a leading cause of bacterially derived foodborne illness worldwide. Human illness is commonly associated with handling and consumption of contaminated poultry products. Three C. jejuni strains were isolated from cecal contents of three different naturally colonized, farm rais...

Extracellular deoxyribonuclease made by group A Streptococcus assists pathogenesis by enhancing evasion of the innate immune response.

PubMed

Sumby, Paul; Barbian, Kent D; Gardner, Donald J; Whitney, Adeline R; Welty, Diane M; Long, R Daniel; Bailey, John R; Parnell, Michael J; Hoe, Nancy P; Adams, Gerald G; Deleo, Frank R; Musser, James M

2005-02-01

Many pathogenic bacteria produce extracellular DNase, but the benefit of this enzymatic activity is not understood. For example, all strains of the human bacterial pathogen group A Streptococcus (GAS) produce at least one extracellular DNase, and most strains make several distinct enzymes. Despite six decades of study, it is not known whether production of DNase by GAS enhances virulence. To test the hypothesis that extracellular DNase is required for normal progression of GAS infection, we generated seven isogenic mutant strains in which the three chromosomal- and prophage-encoded DNases made by a contemporary serotype M1 GAS strain were inactivated. Compared to the wild-type parental strain, the isogenic triple-mutant strain was significantly less virulent in two mouse models of invasive infection. The triple-mutant strain was cleared from the skin injection site significantly faster than the wild-type strain. Preferential clearance of the mutant strain was related to the differential extracellular killing of the mutant and wild-type strains, possibly through degradation of neutrophil extracellular traps, innate immune structures composed of chromatin and granule proteins. The triple-mutant strain was also significantly compromised in its ability to cause experimental pharyngeal disease in cynomolgus macaques. Comparative analysis of the seven DNase mutant strains strongly suggested that the prophage-encoded SdaD2 enzyme is the major DNase that contributes to virulence in this clone. We conclude that extracellular DNase activity made by GAS contributes to disease progression, thereby resolving a long-standing question in bacterial pathogenesis research.

Nanoparticle-based biosensor for the detection of emerging pandemic influenza strains.

PubMed

Kamikawa, Tracy L; Mikolajczyk, Malgorzata G; Kennedy, Michael; Zhang, Pei; Wang, Wei; Scott, Dorothy E; Alocilja, Evangelyn C

2010-12-15

Electrically active magnetic (EAM) nanoparticles, consisting of aniline monomer polymerized around gamma iron(III) oxide (γ-Fe(2)O(3)) cores, serve as the basis of a direct-charge transfer biosensor developed for detection of surface glycoprotein hemagglutinin (HA) from the Influenza A virus (FLUAV) H5N1 (A/Vietnam/1203/04). H5N1 preferentially binds α2,3-linked host glycan receptors. EAM nanoparticles were immunofunctionalized with antibodies against target HA. Glycans preincubated with HA in 10% mouse serum were incubated with anti-HA-EAM complexes. The anti-HA-EAM complexes effectively acted as immunomagnetic separator of HA from mouse serum matrix. EAM nanoparticles served as the biosensor transducer for cyclic voltammetry measurements. The polyaniline was made electrically active by hydrochloric acid doping. Experimental results indicate that the biosensor is able to detect recombinant H5 HA at 1.4 μM in 10% mouse serum, with high specificity for H5 as compared to H1 (H1N1 A/South Carolina/1/18). This novel design applies EAM nanoparticles in a sensitive, specific, affordable, and easy-to-use biosensor with applications in disease monitoring and biosecurity. Copyright © 2010 Elsevier B.V. All rights reserved.

Switching the mode of sucrose utilization by Saccharomyces cerevisiae

PubMed Central

Badotti, Fernanda; Dário, Marcelo G; Alves, Sergio L; Cordioli, Maria Luiza A; Miletti, Luiz C; de Araujo, Pedro S; Stambuk, Boris U

2008-01-01

Background Overflow metabolism is an undesirable characteristic of aerobic cultures of Saccharomyces cerevisiae during biomass-directed processes. It results from elevated sugar consumption rates that cause a high substrate conversion to ethanol and other bi-products, severely affecting cell physiology, bioprocess performance, and biomass yields. Fed-batch culture, where sucrose consumption rates are controlled by the external addition of sugar aiming at its low concentrations in the fermentor, is the classical bioprocessing alternative to prevent sugar fermentation by yeasts. However, fed-batch fermentations present drawbacks that could be overcome by simpler batch cultures at relatively high (e.g. 20 g/L) initial sugar concentrations. In this study, a S. cerevisiae strain lacking invertase activity was engineered to transport sucrose into the cells through a low-affinity and low-capacity sucrose-H+ symport activity, and the growth kinetics and biomass yields on sucrose analyzed using simple batch cultures. Results We have deleted from the genome of a S. cerevisiae strain lacking invertase the high-affinity sucrose-H+ symporter encoded by the AGT1 gene. This strain could still grow efficiently on sucrose due to a low-affinity and low-capacity sucrose-H+ symport activity mediated by the MALx1 maltose permeases, and its further intracellular hydrolysis by cytoplasmic maltases. Although sucrose consumption by this engineered yeast strain was slower than with the parental yeast strain, the cells grew efficiently on sucrose due to an increased respiration of the carbon source. Consequently, this engineered yeast strain produced less ethanol and 1.5 to 2 times more biomass when cultivated in simple batch mode using 20 g/L sucrose as the carbon source. Conclusion Higher cell densities during batch cultures on 20 g/L sucrose were achieved by using a S. cerevisiae strain engineered in the sucrose uptake system. Such result was accomplished by effectively reducing sucrose uptake by the yeast cells, avoiding overflow metabolism, with the concomitant reduction in ethanol production. The use of this modified yeast strain in simpler batch culture mode can be a viable option to more complicated traditional sucrose-limited fed-batch cultures for biomass-directed processes of S. cerevisiae. PMID:18304329

Switching the mode of sucrose utilization by Saccharomyces cerevisiae.

PubMed

Badotti, Fernanda; Dário, Marcelo G; Alves, Sergio L; Cordioli, Maria Luiza A; Miletti, Luiz C; de Araujo, Pedro S; Stambuk, Boris U

2008-02-27

Overflow metabolism is an undesirable characteristic of aerobic cultures of Saccharomyces cerevisiae during biomass-directed processes. It results from elevated sugar consumption rates that cause a high substrate conversion to ethanol and other bi-products, severely affecting cell physiology, bioprocess performance, and biomass yields. Fed-batch culture, where sucrose consumption rates are controlled by the external addition of sugar aiming at its low concentrations in the fermentor, is the classical bioprocessing alternative to prevent sugar fermentation by yeasts. However, fed-batch fermentations present drawbacks that could be overcome by simpler batch cultures at relatively high (e.g. 20 g/L) initial sugar concentrations. In this study, a S. cerevisiae strain lacking invertase activity was engineered to transport sucrose into the cells through a low-affinity and low-capacity sucrose-H+ symport activity, and the growth kinetics and biomass yields on sucrose analyzed using simple batch cultures. We have deleted from the genome of a S. cerevisiae strain lacking invertase the high-affinity sucrose-H+ symporter encoded by the AGT1 gene. This strain could still grow efficiently on sucrose due to a low-affinity and low-capacity sucrose-H+ symport activity mediated by the MALx1 maltose permeases, and its further intracellular hydrolysis by cytoplasmic maltases. Although sucrose consumption by this engineered yeast strain was slower than with the parental yeast strain, the cells grew efficiently on sucrose due to an increased respiration of the carbon source. Consequently, this engineered yeast strain produced less ethanol and 1.5 to 2 times more biomass when cultivated in simple batch mode using 20 g/L sucrose as the carbon source. Higher cell densities during batch cultures on 20 g/L sucrose were achieved by using a S. cerevisiae strain engineered in the sucrose uptake system. Such result was accomplished by effectively reducing sucrose uptake by the yeast cells, avoiding overflow metabolism, with the concomitant reduction in ethanol production. The use of this modified yeast strain in simpler batch culture mode can be a viable option to more complicated traditional sucrose-limited fed-batch cultures for biomass-directed processes of S. cerevisiae.

[Specific aspects and care of lung involvement in adults with cystic fibrosis].

PubMed

Pin, I; Grenet, D; Scheid, P; Domblides, P; Stern, M; Hubert, D

2000-08-01

Respiratory impairment is present in almost all adult cystic fibrosis patients and makes the prognosis. Viscous, infected and abundant secretions, inflammation and bronchial oedema, bronchoconstriction and respiratory muscle fatigue lead to airway obstruction, bronchiectasis and respiratory failure. The disease is preferentially located in the upper lobes. Exacerbations of the disease are due to bronchial infections and are often responsible for drops of the respiratory function. Regular spirometric surveillance is fundamental for the prognosis and the assessment of the effects of the treatment. Among adult patients chronic colonisation with mucoid and often multiresistant strains of Pseudomonas Aeruginosa are common. It is treated with i.v. high doses antibiotic courses and nebulized antibiotics between i.v. courses. Respiratory failure may require long term oxygen and non invasive mechanical ventilation. Systemic hypervascularization around the bronchiectasis may lead to moderate to severe hemoptysis, which may require embolization. Pneumothorax are associated with poor prognosis and are treated by pleural drainage and if failure by thoracoscopy.

Influence of Dietary Factors on Helicobacter pylori and CagA Seroprevalence in Bulgaria

PubMed Central

Ilieva, Juliana; Andreev, Nikolay; Mitov, Ivan

2017-01-01

The aim of this study was to assess the association between some dietary factors and prevalence of H. pylori infection or strain virulence in 294 adult asymptomatic blood donors. Methods. Seroprevalence was evaluated using ELISA. Logistic regression was used. Results. Anti-H. pylori IgG prevalence was 72.4%, and CagA IgG seroprevalence was 49.3%. In the multivariate analyses, the frequent (>5 days per week) honey consumption was associated with both reduced H. pylori seroprevalence OR, 0.68 with 95% confidence interval (CI), 0.473–0.967 and reduced CagA IgG seroprevalence OR, 0.65 with 95% CI, 0.486–0859. Frequent (>5 days per week) yoghurt consumption also was associated with lower H. pylori virulence of the strains (CagA IgG OR, 0.56 with 95% CI, 0.341–0.921). Smoking and consumption of the other dietary factors resulted in no significant differences in the prevalence of H. pylori IgG and CagA IgG within the subject groups. Conclusion. To the best of our knowledge, this is the first report revealing reverse associations between honey or yoghurt consumption and CagA IgG prevalence as well as between frequent honey consumption and lower prevalence of the H. pylori infection. Regular honey and yoghurt consumption can be of value as a supplement in the control of H. pylori therapy. PMID:28659975

Influence of Dietary Factors on Helicobacter pylori and CagA Seroprevalence in Bulgaria.

PubMed

Yordanov, Daniel; Boyanova, Lyudmila; Markovska, Rumyana; Ilieva, Juliana; Andreev, Nikolay; Gergova, Galina; Mitov, Ivan

2017-01-01

The aim of this study was to assess the association between some dietary factors and prevalence of H. pylori infection or strain virulence in 294 adult asymptomatic blood donors. Methods . Seroprevalence was evaluated using ELISA. Logistic regression was used. Results . Anti- H. pylori IgG prevalence was 72.4%, and CagA IgG seroprevalence was 49.3%. In the multivariate analyses, the frequent (>5 days per week) honey consumption was associated with both reduced H. pylori seroprevalence OR, 0.68 with 95% confidence interval (CI), 0.473-0.967 and reduced CagA IgG seroprevalence OR, 0.65 with 95% CI, 0.486-0859. Frequent (>5 days per week) yoghurt consumption also was associated with lower H. pylori virulence of the strains (CagA IgG OR, 0.56 with 95% CI, 0.341-0.921). Smoking and consumption of the other dietary factors resulted in no significant differences in the prevalence of H. pylori IgG and CagA IgG within the subject groups. Conclusion . To the best of our knowledge, this is the first report revealing reverse associations between honey or yoghurt consumption and CagA IgG prevalence as well as between frequent honey consumption and lower prevalence of the H. pylori infection. Regular honey and yoghurt consumption can be of value as a supplement in the control of H. pylori therapy.

Identification of Nitrogen Consumption Genetic Variants in Yeast Through QTL Mapping and Bulk Segregant RNA-Seq Analyses.

PubMed

Cubillos, Francisco A; Brice, Claire; Molinet, Jennifer; Tisné, Sebastién; Abarca, Valentina; Tapia, Sebastián M; Oporto, Christian; García, Verónica; Liti, Gianni; Martínez, Claudio

2017-06-07

Saccharomyces cerevisiae is responsible for wine must fermentation. In this process, nitrogen represents a limiting nutrient and its scarcity results in important economic losses for the wine industry. Yeast isolates use different strategies to grow in poor nitrogen environments and their genomic plasticity enables adaptation to multiple habitats through improvements in nitrogen consumption. Here, we used a highly recombinant S. cerevisiae multi-parent population (SGRP-4X) derived from the intercross of four parental strains of different origins to identify new genetic variants responsible for nitrogen consumption differences during wine fermentation. Analysis of 165 fully sequenced F12 segregants allowed us to map 26 QTL in narrow intervals for 14 amino acid sources and ammonium, the majority of which represent genomic regions previously unmapped for these traits. To complement this strategy, we performed Bulk segregant RNA-seq (BSR-seq) analysis in segregants exhibiting extremely high and low ammonium consumption levels. This identified several QTL overlapping differentially expressed genes and refined the gene candidate search. Based on these approaches, we were able to validate ARO1 , PDC1 , CPS1 , ASI2 , LYP1 , and ALP1 allelic variants underlying nitrogen consumption differences between strains, providing evidence of many genes with small phenotypic effects. Altogether, these variants significantly shape yeast nitrogen consumption with important implications for evolution, ecological, and quantitative genomics. Copyright © 2017 Cubillos et al.

Identification of Nitrogen Consumption Genetic Variants in Yeast Through QTL Mapping and Bulk Segregant RNA-Seq Analyses

PubMed Central

Cubillos, Francisco A.; Brice, Claire; Molinet, Jennifer; Tisné, Sebastién; Abarca, Valentina; Tapia, Sebastián M.; Oporto, Christian; García, Verónica; Liti, Gianni; Martínez, Claudio

2017-01-01

Saccharomyces cerevisiae is responsible for wine must fermentation. In this process, nitrogen represents a limiting nutrient and its scarcity results in important economic losses for the wine industry. Yeast isolates use different strategies to grow in poor nitrogen environments and their genomic plasticity enables adaptation to multiple habitats through improvements in nitrogen consumption. Here, we used a highly recombinant S. cerevisiae multi-parent population (SGRP-4X) derived from the intercross of four parental strains of different origins to identify new genetic variants responsible for nitrogen consumption differences during wine fermentation. Analysis of 165 fully sequenced F12 segregants allowed us to map 26 QTL in narrow intervals for 14 amino acid sources and ammonium, the majority of which represent genomic regions previously unmapped for these traits. To complement this strategy, we performed Bulk segregant RNA-seq (BSR-seq) analysis in segregants exhibiting extremely high and low ammonium consumption levels. This identified several QTL overlapping differentially expressed genes and refined the gene candidate search. Based on these approaches, we were able to validate ARO1, PDC1, CPS1, ASI2, LYP1, and ALP1 allelic variants underlying nitrogen consumption differences between strains, providing evidence of many genes with small phenotypic effects. Altogether, these variants significantly shape yeast nitrogen consumption with important implications for evolution, ecological, and quantitative genomics. PMID:28592651

Phase composition of lipoprotein SM/cholesterol/PtdCho affects FA specificity of sPLA2s.

PubMed

Kuksis, Arnis; Pruzanski, Waldemar

2008-10-01

We have previously reported preferential release of polyunsaturated FAs during hydrolysis of lipoprotein phosphatidylcholine (PtdCho) by group X secretory phospholipase A2 (sPLA2) and preferential release of oligounsaturated FAs during hydrolysis of lipoprotein PtdCho by group V sPLA2, but the mechanism of this selectivity has remained unknown. We now show that the rate and specificity of hydrolysis are affected by relative increases in endogenous SM and free cholesterol (FC) during the lipase digestion. The highest preference for arachidonate release from LDL and HDL by group X sPLA2 was observed for residual SM/PtdCho molar ratio of 1.2 and 0.4, compared with the respective starting ratios of 0.4 and 0.2, as measured by liquid chromatography/electrospray ionization-mass spectrometry. Group V sPLA2 showed preferential release of linoleate from LDL and HDL at SM/PtdCho ratio 1.5 and 0.6, respectively. We have attributed the change in FA specificity to segregation of molecular species of PtdCho and of sPLA2s between disordered and ordered SM/FC/PtdCho lipid phases. The increases in SM and FC during digestion with group IIA sPLA2 were more limited, and a preferential hydrolysis of any FAs was not observed. The significance of SM and FC SM and FC accumulation during sPLA2 hydrolysis of lipoprotein PtdCho has been previously overlooked.

Metabolism of Oxo-Bile Acids and Characterization of Recombinant 12α-Hydroxysteroid Dehydrogenases from Bile Acid 7α-Dehydroxylating Human Gut Bacteria.

PubMed

Doden, Heidi; Sallam, Lina A; Devendran, Saravanan; Ly, Lindsey; Doden, Greta; Daniel, Steven L; Alves, João M P; Ridlon, Jason M

2018-05-15

Bile acids are important cholesterol-derived nutrient signaling hormones, synthesized in the liver, that act as detergents to solubilize dietary lipids. Bile acid 7α-dehydroxylating gut bacteria generate the toxic bile acids deoxycholic acid and lithocholic acid from host bile acids. The ability of these bacteria to remove the 7-hydroxyl group is partially dependent on 7α-hydroxysteroid dehydrogenase (HSDH) activity, which reduces 7-oxo-bile acids generated by other gut bacteria. 3α-HSDH has an important enzymatic activity in the bile acid 7α-dehydroxylation pathway. 12α-HSDH activity has been reported for the low-activity bile acid 7α-dehydroxylating bacterium Clostridium leptum ; however, this activity has not been reported for high-activity bile acid 7α-dehydroxylating bacteria, such as Clostridium scindens , Clostridium hylemonae , and Clostridium hiranonis Here, we demonstrate that these strains express bile acid 12α-HSDH. The recombinant enzymes were characterized from each species and shown to preferentially reduce 12-oxolithocholic acid to deoxycholic acid, with low activity against 12-oxochenodeoxycholic acid and reduced activity when bile acids were conjugated to taurine or glycine. Phylogenetic analysis suggests that 12α-HSDH is widespread among Firmicutes , Actinobacteria in the Coriobacteriaceae family, and human gut Archaea IMPORTANCE 12α-HSDH activity has been established in the medically important bile acid 7α-dehydroxylating bacteria C. scindens , C. hiranonis , and C. hylemonae Experiments with recombinant 12α-HSDHs from these strains are consistent with culture-based experiments that show a robust preference for 12-oxolithocholic acid over 12-oxochenodeoxycholic acid. Phylogenetic analysis identified novel members of the gut microbiome encoding 12α-HSDH. Future reengineering of 12α-HSDH enzymes to preferentially oxidize cholic acid may provide a means to industrially produce the therapeutic bile acid ursodeoxycholic acid. In addition, a cholic acid-specific 12α-HSDH expressed in the gut may be useful for the reduction in deoxycholic acid concentration, a bile acid implicated in cancers of the gastrointestinal (GI) tract. Copyright © 2018 American Society for Microbiology.

Cyclic Degradation Behavior of < 001 > -Oriented Fe-Mn-Al-Ni Single Crystals in Tension

NASA Astrophysics Data System (ADS)

Vollmer, M.; Kriegel, M. J.; Krooß, P.; Martin, S.; Klemm, V.; Weidner, A.; Chumlyakov, Y.; Biermann, H.; Rafaja, D.; Niendorf, T.

2017-12-01

In the present study, functional fatigue behavior of a near 〈001〉-oriented Fe-Mn-Al-Ni single crystal was investigated under tensile load. An incremental strain test up to 3.5% strain and cyclic tests up to 25 cycles revealed rapid pseudoelastic degradation. Progressive microstructural degradation was studied by in situ scanning electron microscopy. The results show a partially inhibited reactivation of previously formed martensite and proceeding activation of untransformed areas in subsequent cycles. The preferentially formed martensite variants were identified by means of Schmid factor calculation and the Kurdjumov-Sachs relationship. Post mortem transmission electron microscopy investigations shed light on the prevailing degradation mechanisms. Different types of dislocations were found promoting the progressive degradation during cyclic loading.

Preferential expression of an ammonium transporter and of two putative nitrate transporters in root hairs of tomato.

PubMed Central

Lauter, F R; Ninnemann, O; Bucher, M; Riesmeier, J W; Frommer, W B

1996-01-01

Root hairs as specialized epidermal cells represent part of the outermost interface between a plant and its soil environment. They make up to 70% of the root surface and, therefore, are likely to contribute significantly to nutrient uptake. To study uptake systems for mineral nitrogen, three genes homologous to Arabidopsis nitrate and ammonium transporters (AtNrt1 and AtAmt1) were isolated from a root hair-specific tomato cDNA library. Accumulation of LeNrt1-1, LeNrt1-2, and LeAmt1 transcripts was root-specific, with no detectable transcripts in stems or leaves. Expression was root cell type-specific and regulated by nitrogen availability. LeNrt1-2 mRNA accumulation was restricted to root hairs that had been exposed to nitrate. In contrast, LeNrt1-1 transcripts were detected in root hairs as well as other root tissues under all nitrogen treatments applied. Analogous to LeNrt1-1, the gene LeAmt1 was expressed under all nitrogen conditions tested, and root hair-specific mRNA accumulation was highest following exposure to ammonium. Expression of LeAMT1 in an ammonium uptake-deficient yeast strain restored growth on low ammonium medium, confirming its involvement in ammonium transport. Root hair specificity and characteristics of substrate regulation suggest an important role of the three genes in uptake of mineral nitrogen. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 PMID:8755617

Finite Element Modeling of Reheat Stretch Blow Molding of PET

NASA Astrophysics Data System (ADS)

Krishnan, Dwarak; Dupaix, Rebecca B.

2004-06-01

Poly (ethylene terephthalate) or PET is a polymer used as a packaging material for consumer products such as beverages, food or other liquids, and in other applications including drawn fibers and stretched films. Key features that make it widely used are its transparency, dimensional stability, gas impermeability, impact resistance, and high stiffness and strength in certain preferential directions. These commercially useful properties arise from the fact that PET crystallizes upon deformation above the glass transition temperature. Additionally, this strain-induced crystallization causes the deformation behavior of PET to be highly sensitive to processing conditions. It is thus crucial for engineers to be able to predict its performance at various process temperatures, strain rates and strain states so as to optimize the manufacturing process. In addressing these issues; a finite element analysis of the reheat blow molding process with PET has been carried out using ABAQUS. The simulation employed a constitutive model for PET developed by Dupaix and Boyce et al.. The model includes the combined effects of molecular orientation and strain-induced crystallization on strain hardening when the material is deformed above the glass transition temperature. The simulated bottles were also compared with actual blow molded bottles to evaluate the validity of the simulation.

Transcript expression plasticity as a response to alternative larval host plants in the speciation process of corn and rice strains of Spodoptera frugiperda.

PubMed

Silva-Brandão, Karina Lucas; Horikoshi, Renato Jun; Bernardi, Daniel; Omoto, Celso; Figueira, Antonio; Brandão, Marcelo Mendes

2017-10-16

Our main purpose was to evaluate the expression of plastic and evolved genes involved in ecological speciation in the noctuid moth Spodoptera frugiperda, the fall armyworm (FAW); and to demonstrate how host plants might influence lineage differentiation in this polyphagous insect. FAW is an important pest of several crops worldwide, and it is differentiated into host plant-related strains, corn (CS) and rice strains (RS). RNA-Seq and transcriptome characterization were applied to evaluate unbiased genetic expression differences in larvae from the two strains, fed on primary (corn) and alternative (rice) host plants. We consider that genes that are differently regulated by the same FAW strain, as a response to different hosts, are "plastic". Otherwise, differences in gene expression between the two strains fed on the same host are considered constitutive differences. Individual performance parameters (larval and pupal weight) varied among conditions (strains vs. hosts). A total of 3657 contigs was related to plastic response, and 2395 contigs were differentially regulated in the two strains feeding on preferential and alternative hosts (constitutive contigs). Three molecular functions were present in all comparisons, both down- and up-regulated: oxidoreductase activity, metal-ion binding, and hydrolase activity. Metabolization of foreign chemicals is among the key functions involved in the phenotypic variation of FAW strains. From an agricultural perspective, high plasticity in families of detoxifying genes indicates the capacity for a rapid response to control compounds such as insecticides.

Gene expression patterns and dynamics of the colonization of common bean (Phaseolus vulgaris L.) by highly virulent and weakly virulent strains of Fusarium oxysporum

PubMed Central

Niño-Sánchez, Jonathan; Tello, Vega; Casado-del Castillo, Virginia; Thon, Michael R.; Benito, Ernesto P.; Díaz-Mínguez, José María

2015-01-01

The dynamics of root and hypocotyl colonization, and the gene expression patterns of several fungal virulence factors and plant defense factors have been analyzed and compared in the interaction of two Fusarium oxysporum f. sp. phaseoli strains displaying clear differences in virulence, with a susceptible common bean cultivar. The growth of the two strains on the root surface and the colonization of the root was quantitatively similar although the highly virulent (HV) strain was more efficient reaching the central root cylinder. The main differences between both strains were found in the temporal and spatial dynamics of crown root and hypocotyl colonization. The increase of fungal biomass in the crown root was considerably larger for the HV strain, which, after an initial stage of global colonization of both the vascular cylinder and the parenchymal cells, restricted its growth to the newly differentiated xylem vessels. The weakly virulent (WV) strain was a much slower and less efficient colonizer of the xylem vessels, showing also growth in the intercellular spaces of the parenchyma. Most of the virulence genes analyzed showed similar expression patterns in both strains, except SIX1, SIX6 and the gene encoding the transcription factor FTF1, which were highly upregulated in root crown and hypocotyl. The response induced in the infected plant showed interesting differences for both strains. The WV strain induced an early and strong transcription of the PR1 gene, involved in SAR response, while the HV strain preferentially induced the early expression of the ethylene responsive factor ERF2. PMID:25883592

Xenopus origin recognition complex (ORC) initiates DNA replication preferentially at sequences targeted by Schizosaccharomyces pombe ORC

PubMed Central

Kong, Daochun; Coleman, Thomas R.; DePamphilis, Melvin L.

2003-01-01

Budding yeast (Saccharomyces cerevisiae) origin recognition complex (ORC) requires ATP to bind specific DNA sequences, whereas fission yeast (Schizosaccharomyces pombe) ORC binds to specific, asymmetric A:T-rich sites within replication origins, independently of ATP, and frog (Xenopus laevis) ORC seems to bind DNA non-specifically. Here we show that despite these differences, ORCs are functionally conserved. Firstly, SpOrc1, SpOrc4 and SpOrc5, like those from other eukaryotes, bound ATP and exhibited ATPase activity, suggesting that ATP is required for pre-replication complex (pre-RC) assembly rather than origin specificity. Secondly, SpOrc4, which is solely responsible for binding SpORC to DNA, inhibited up to 70% of XlORC-dependent DNA replication in Xenopus egg extract by preventing XlORC from binding to chromatin and assembling pre-RCs. Chromatin-bound SpOrc4 was located at AT-rich sequences. XlORC in egg extract bound preferentially to asymmetric A:T-sequences in either bare DNA or in sperm chromatin, and it recruited XlCdc6 and XlMcm proteins to these sequences. These results reveal that XlORC initiates DNA replication preferentially at the same or similar sites to those targeted in S.pombe. PMID:12840006

Mutual Cross-Feeding Interactions between Bifidobacterium longum subsp. longum NCC2705 and Eubacterium rectale ATCC 33656 Explain the Bifidogenic and Butyrogenic Effects of Arabinoxylan Oligosaccharides

PubMed Central

Rivière, Audrey; Gagnon, Mérilie; Weckx, Stefan; Roy, Denis

2015-01-01

Arabinoxylan oligosaccharides (AXOS) are a promising class of prebiotics that have the potential to stimulate the growth of bifidobacteria and the production of butyrate in the human colon, known as the bifidogenic and butyrogenic effects, respectively. Although these dual effects of AXOS are considered beneficial for human health, their underlying mechanisms are still far from being understood. Therefore, this study investigated the metabolic interactions between Bifidobacterium longum subsp. longum NCC2705 (B. longum NCC2705), an acetate producer and arabinose substituent degrader of AXOS, and Eubacterium rectale ATCC 33656, an acetate-converting butyrate producer. Both strains belong to prevalent species of the human colon microbiota. The strains were grown on AXOS during mono- and coculture fermentations, and their growth, AXOS consumption, metabolite production, and expression of key genes were monitored. The results showed that the growth of both strains and gene expression in both strains were affected by cocultivation and that these effects could be linked to changes in carbohydrate consumption and concomitant metabolite production. The consumption of the arabinose substituents of AXOS by B. longum NCC2705 with the concomitant production of acetate allowed E. rectale ATCC 33656 to produce butyrate (by means of a butyryl coenzyme A [CoA]:acetate CoA-transferase), explaining the butyrogenic effect of AXOS. Eubacterium rectale ATCC 33656 released xylose from the AXOS substrate, which favored the B. longum NCC2705 production of acetate, explaining the bifidogenic effect of AXOS. Hence, those interactions represent mutual cross-feeding mechanisms that favor the coexistence of bifidobacterial strains and butyrate producers in the same ecological niche. In conclusion, this study provides new insights into the bifidogenic and butyrogenic effects of AXOS. PMID:26319874

Young Attitude on Sustainable Development: A Case Study

ERIC Educational Resources Information Center

Tuncer, Gaye; Sungur, Semra; Tekkaya, Ceren; Ertepinar, Hamide

2005-01-01

Patterns of consumption and production are not sustainable in developed/developing countries. In developed countries, the levels of pollution, especially those causing global change, are far too high and trends go in the wrong direction. In developing countries, there is too much strain on the local resource base, and this strain is increasing due…

Flexible strain sensors with high performance based on metallic glass thin film

NASA Astrophysics Data System (ADS)

Xian, H. J.; Cao, C. R.; Shi, J. A.; Zhu, X. S.; Hu, Y. C.; Huang, Y. F.; Meng, S.; Gu, L.; Liu, Y. H.; Bai, H. Y.; Wang, W. H.

2017-09-01

Searching strain sensitive materials for electronic skin is of crucial significance because of the restrictions of current materials such as poor electrical conductivity, large energy consumption, complex manufacturing process, and high cost. Here, we report a flexible strain sensor based on the Zr55Cu30Ni5Al10 metallic glass thin film which we name metallic glass skin. The metallic glass skin, synthesized by ion beam deposition, exhibits piezoresistance effects with a gauge factor of around 2.86, a large detectable strain range (˜1% or 180° bending angle), and good conductivity. Compared to other e-skin materials, the temperature coefficient of resistance of the metallic glass skin is extremely low (9.04 × 10-6 K-1), which is essential for the reduction in thermal drift. In addition, the metallic glass skin exhibits distinct antibacterial behavior desired for medical applications, also excellent reproducibility and repeatability (over 1000 times), nearly perfect linearity, low manufacturing cost, and negligible energy consumption, all of which are required for electronic skin for practical applications.

The Genome-Based Metabolic Systems Engineering to Boost Levan Production in a Halophilic Bacterial Model.

PubMed

Aydin, Busra; Ozer, Tugba; Oner, Ebru Toksoy; Arga, Kazim Yalcin

2018-03-01

Metabolic systems engineering is being used to redirect microbial metabolism for the overproduction of chemicals of interest with the aim of transforming microbial hosts into cellular factories. In this study, a genome-based metabolic systems engineering approach was designed and performed to improve biopolymer biosynthesis capability of a moderately halophilic bacterium Halomonas smyrnensis AAD6 T producing levan, which is a fructose homopolymer with many potential uses in various industries and medicine. For this purpose, the genome-scale metabolic model for AAD6 T was used to characterize the metabolic resource allocation, specifically to design metabolic engineering strategies for engineered bacteria with enhanced levan production capability. Simulations were performed in silico to determine optimal gene knockout strategies to develop new strains with enhanced levan production capability. The majority of the gene knockout strategies emphasized the vital role of the fructose uptake mechanism, and pointed out the fructose-specific phosphotransferase system (PTS fru ) as the most promising target for further metabolic engineering studies. Therefore, the PTS fru of AAD6 T was restructured with insertional mutagenesis and triparental mating techniques to construct a novel, engineered H. smyrnensis strain, BMA14. Fermentation experiments were carried out to demonstrate the high efficiency of the mutant strain BMA14 in terms of final levan concentration, sucrose consumption rate, and sucrose conversion efficiency, when compared to the AAD6 T . The genome-based metabolic systems engineering approach presented in this study might be considered an efficient framework to redirect microbial metabolism for the overproduction of chemicals of interest, and the novel strain BMA14 might be considered a potential microbial cell factory for further studies aimed to design levan production processes with lower production costs.

Recurrent Reverse Evolution Maintains Polymorphism after Strong Bottlenecks in Commensal Gut Bacteria

PubMed Central

Ramiro, Ricardo S.; Barroso-Batista, João; Güleresi, Daniela; Lourenço, Marta; Gordo, Isabel

2017-01-01

Abstract The evolution of new strains within the gut ecosystem is poorly understood. We used a natural but controlled system to follow the emergence of intraspecies diversity of commensal Escherichia coli, during three rounds of adaptation to the mouse gut (∼1,300 generations). We previously showed that, in the first round, a strongly beneficial phenotype (loss-of-function for galactitol consumption; gat-negative) spread to >90% frequency in all colonized mice. Here, we show that this loss-of-function is repeatedly reversed when a gat-negative clone colonizes new mice. The regain of function occurs via compensatory mutation and reversion, the latter leaving no trace of past adaptation. We further show that loss-of-function adaptive mutants reevolve, after colonization with an evolved gat-positive clone. Thus, even under strong bottlenecks a regime of strong-mutation-strong-selection dominates adaptation. Coupling experiments and modeling, we establish that reverse evolution recurrently generates two coexisting phenotypes within the microbiota that can or not consume galactitol (gat-positive and gat-negative, respectively). Although the abundance of the dominant strain, the gat-negative, depends on the microbiota composition, gat-positive abundance is independent of the microbiota composition and can be precisely manipulated by supplementing the diet with galactitol. These results show that a specific diet is able to change the abundance of specific strains. Importantly, we find polymorphism for these phenotypes in indigenous Enterobacteria of mice and man. Our results demonstrate that natural selection can greatly overwhelm genetic drift at structuring the strain diversity of gut commensals and that competition for limiting resources may be a key mechanism for maintaining polymorphism in the gut. PMID:28961745

Crohn's disease-associated adherent-invasive Escherichia coli adhesion is enhanced by exposure to the ubiquitous dietary polysaccharide maltodextrin.

PubMed

Nickerson, Kourtney P; McDonald, Christine

2012-01-01

Crohn's disease (CD) is associated with intestinal dysbiosis evidenced by an altered microbiome forming thick biofilms on the epithelium. Additionally, adherent-invasive E. coli (AIEC) strains are frequently isolated from ileal lesions of CD patients indicating a potential role for these strains in disease pathogenesis. The composition and characteristics of the host microbiome are influenced by environmental factors, particularly diet. Polysaccharides added to food as emulsifiers, stabilizers or bulking agents have been linked to bacteria-associated intestinal disorders. The escalating consumption of polysaccharides in Western diets parallels an increased incidence of CD during the latter 20(th) century. In this study, the effect of a polysaccharide panel on adhesiveness of the CD-associated AIEC strain LF82 was analyzed to determine if these food additives promote disease-associated bacterial phenotypes. Maltodextrin (MDX), a polysaccharide derived from starch hydrolysis, markedly enhanced LF82 specific biofilm formation. Biofilm formation of multiple other E. coli strains was also promoted by MDX. MDX-induced E. coli biofilm formation was independent of polysaccharide chain length indicating a requirement for MDX metabolism. MDX exposure induced type I pili expression, which was required for MDX-enhanced biofilm formation. MDX also increased bacterial adhesion to human intestinal epithelial cell monolayers in a mechanism dependent on type 1 pili and independent of the cellular receptor CEACAM6, suggesting a novel mechanism of epithelial cell adhesion. Analysis of mucosa-associated bacteria from individuals with and without CD showed increased prevalence of malX, a gene essential for MDX metabolism, uniquely in the ileum of CD patients. These findings demonstrate that the ubiquitous dietary component MDX enhances E. coli adhesion and suggests a mechanism by which Western diets rich in specific polysaccharides may promote dysbiosis of gut microbes and contribute to disease susceptibility.

Genetic divergence in the transcriptional engram of chronic alcohol abuse: A laser-capture RNA-seq study of the mouse mesocorticolimbic system.

PubMed

Mulligan, Megan K; Mozhui, Khyobeni; Pandey, Ashutosh K; Smith, Maren L; Gong, Suzhen; Ingels, Jesse; Miles, Michael F; Lopez, Marcelo F; Lu, Lu; Williams, Robert W

2017-02-01

Genetic factors that influence the transition from initial drinking to dependence remain enigmatic. Recent studies have leveraged chronic intermittent ethanol (CIE) paradigms to measure changes in brain gene expression in a single strain at 0, 8, 72 h, and even 7 days following CIE. We extend these findings using LCM RNA-seq to profile expression in 11 brain regions in two inbred strains - C57BL/6J (B6) and DBA/2J (D2) - 72 h following multiple cycles of ethanol self-administration and CIE. Linear models identified differential expression based on treatment, region, strain, or interactions with treatment. Nearly 40% of genes showed a robust effect (FDR < 0.01) of region, and hippocampus CA1, cortex, bed nucleus stria terminalis, and nucleus accumbens core had the highest number of differentially expressed genes after treatment. Another 8% of differentially expressed genes demonstrated a robust effect of strain. As expected, based on similar studies in B6, treatment had a much smaller impact on expression; only 72 genes (p < 0.01) are modulated by treatment (independent of region or strain). Strikingly, many more genes (415) show a strain-specific and largely opposite response to treatment and are enriched in processes related to RNA metabolism, transcription factor activity, and mitochondrial function. Over 3 times as many changes in gene expression were detected in D2 compared to B6, and weighted gene co-expression network analysis (WGCNA) module comparison identified more modules enriched for treatment effects in D2. Substantial strain differences exist in the temporal pattern of transcriptional neuroadaptation to CIE, and these may drive individual differences in risk of addiction following excessive alcohol consumption. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of a eucaloric reduced-carbohydrate diet on body composition and fat distribution in women with PCOS.

PubMed

Goss, Amy M; Chandler-Laney, Paula C; Ovalle, Fernando; Goree, Laura Lee; Azziz, Ricardo; Desmond, Renee A; Wright Bates, G; Gower, Barbara A

2014-10-01

To determine if consumption of a reduced-carbohydrate (CHO) diet would result in preferential loss of adipose tissue under eucaloric conditions, and whether changes in adiposity were associated with changes in postprandial insulin concentration. In a crossover-diet intervention, 30 women with PCOS consumed a reduced-CHO diet (41:19:40% energy from CHO:protein:fat) for 8 weeks and a standard diet (55:18:27) for 8 weeks. Body composition by DXA and fat distribution by CT were assessed at baseline and following each diet phase. Insulin AUC was obtained from a solid meal test (SMT) during each diet phase. Participants lost 3.7% and 2.2% total fat following the reduced-CHO diet and STD diet, resp. (p<0.05 for difference between diets). The reduced-CHO diet induced a decrease in subcutaneous-abdominal, intra-abdominal, and thigh-intermuscular adipose tissue (-7.1%, -4.6%, and -11.5%, resp.), and the STD diet induced a decrease in total lean mass. Loss of fat mass following the reduced CHO diet arm was associated with lower insulin AUC (p<0.05) during the SMT. In women with PCOS, consumption of a diet lower in CHO resulted in preferential loss of fat mass from metabolically harmful adipose depots, whereas a diet high in CHO appeared to promote repartitioning of lean mass to fat mass. Copyright © 2014 Elsevier Inc. All rights reserved.

Substrate utilization profiles of bacterial strains in plankton from the River Warnow, a humic and eutrophic river in north Germany.

PubMed

Freese, Heike M; Eggert, Anja; Garland, Jay L; Schumann, Rhena

2010-01-01

Bacteria are very important degraders of organic substances in aquatic environments. Despite their influential role in the carbon (and many other element) cycle(s), the specific genetic identity of active bacteria is mostly unknown, although contributing phylogenetic groups had been investigated. Moreover, the degree to which phenotypic potential (i. e., utilization of environmentally relevant carbon substrates) is related to the genomic identity of bacteria or bacterial groups is unclear. The present study compared the genomic fingerprints of 27 bacterial isolates from the humic River Warnow with their ability to utilize 14 environmentally relevant substrates. Acetate was the only substrate utilized by all bacterial strains. Only 60% of the strains respired glucose, but this substrate always stimulated the highest bacterial activity (respiration and growth). Two isolates, both closely related to the same Pseudomonas sp., also had very similar substrate utilization patterns. However, similar substrate utilization profiles commonly belonged to genetically different strains (e.g., the substrate profile of Janthinobacterium lividum OW6/RT-3 and Flavobacterium sp. OW3/15-5 differed by only three substrates). Substrate consumption was sometimes totally different for genetically related isolates. Thus, the genomic profiles of bacterial strains were not congruent with their different substrate utilization profiles. Additionally, changes in pre-incubation conditions strongly influenced substrate utilization. Therefore, it is problematic to infer substrate utilization and especially microbial dissolved organic matter transformation in aquatic systems from bacterial molecular taxonomy.

Analysis of metabolisms and transports of xylitol using xylose- and xylitol-assimilating Saccharomyces cerevisiae.

PubMed

Tani, Tatsunori; Taguchi, Hisataka; Akamatsu, Takashi

2017-05-01

To clarify the relationship between NAD(P) + /NAD(P)H redox balances and the metabolisms of xylose or xylitol as carbon sources, we analyzed aerobic and anaerobic batch cultures of recombinant Saccharomyces cerevisiae in a complex medium containing 20 g/L xylose or 20 g/L xylitol at pH 5.0 and 30°C. The TDH3p-GAL2 or gal80Δ strain completely consumed the xylose within 24 h and aerobically consumed 92-100% of the xylitol within 96 h, but anaerobically consumed only 20% of the xylitol within 96 h. Cells of both strains grew well in aerobic culture. The addition of acetaldehyde (an effective oxidizer of NADH) increased the xylitol consumption by the anaerobically cultured strain. These results indicate that in anaerobic culture, NAD + generated in the NAD(P)H-dependent xylose reductase reaction was likely needed in the NAD + -dependent xylitol dehydrogenase reaction, whereas in aerobic culture, the NAD + generated by oxidation of NADH in the mitochondria is required in the xylitol dehydrogenase reaction. The role of Gal2 and Fps1 in importing xylitol into the cytosol and exporting it from the cells was analyzed by examining the xylitol consumption in aerobic culture and the export of xylitol metabolized from xylose in anaerobic culture, respectively. The xylitol consumptions of gal80Δ gal2Δ and gal80Δ gal2Δ fps1Δ strains were reduced by 81% and 88% respectively, relative to the gal80Δ strain. The maximum xylitol concentration accumulated by the gal80Δ, gal80Δ gal2Δ, and gal80Δ gal2Δ fps1Δ strains was 7.25 g/L, 5.30 g/L, and 4.27 g/L respectively, indicating that Gal2 and Fps1 transport xylitol both inward and outward. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

The PapG-adhesin at the tip of P-fimbriae provides Escherichia coli with a competitive edge in experimental bladder infections of cynomolgus monkeys

PubMed Central

1995-01-01

Human urinary tract infection is an infectious disease that depends on a series of host-microbial interactions. The bacteria first colonize the colon and then the periurethral/vaginal areas; they ascend to and infect first the bladder and then the kidneys. Expression of Escherichia coli P-fimbriae constitutes the strongest correlation to renal pathogenicity, but is also related to first-time cystitis in children. The role of P-fimbriae in the preceding steps in the infectious process is unknown. To examine this, we constructed, from a P-fimbriated E. coli strain with a class II G-adhesin preferentially binding to globoside, one isogenic mutant lacking the G-adhesin and another isogenic mutant in which we replaced the papG class II allele with a class III adhesin preferentially binding to the Forssman antigen. We report here the comparison of the adhesin knockout mutant (DS17-8) and the class-switch mutant (DS17-1) with the wild-type (DS17) for in vivo colonization of the gut, vagina, and bladder of cynomolgus monkeys. It was recently shown that the class II tip G-adhesin is a prerequisite for acute pyelonephritis to occur in the monkey model in the absence of other kidney-specific adhesins or obstruction of the urinary flow. Here we show that it is not required for bladder infection but gives a competitive advantage in mixed infections. In the vagina and colon, the G-adhesin gives no competitive advantage. PMID:7500014

Identification of a pair of phospholipid:diacylglycerol acyltransferases from developing flax (Linum usitatissimum L.) seed catalyzing the selective production of trilinolenin.

PubMed

Pan, Xue; Siloto, Rodrigo M P; Wickramarathna, Aruna D; Mietkiewska, Elzbieta; Weselake, Randall J

2013-08-16

The oil from flax (Linum usitatissimum L.) has high amounts of α-linolenic acid (ALA; 18:3(cis)(Δ9,12,15)) and is one of the richest sources of omega-3 polyunsaturated fatty acids (ω-3-PUFAs). To produce ∼57% ALA in triacylglycerol (TAG), it is likely that flax contains enzymes that can efficiently transfer ALA to TAG. To test this hypothesis, we conducted a systematic characterization of TAG-synthesizing enzymes from flax. We identified several genes encoding acyl-CoA:diacylglycerol acyltransferases (DGATs) and phospholipid:diacylglycerol acyltransferases (PDATs) from the flax genome database. Due to recent genome duplication, duplicated gene pairs have been identified for all genes except DGAT2-2. Analysis of gene expression indicated that two DGAT1, two DGAT2, and four PDAT genes were preferentially expressed in flax embryos. Yeast functional analysis showed that DGAT1, DGAT2, and two PDAT enzymes restored TAG synthesis when produced recombinantly in yeast H1246 strain. The activity of particular PDAT enzymes (LuPDAT1 and LuPDAT2) was stimulated by the presence of ALA. Further seed-specific expression of flax genes in Arabidopsis thaliana indicated that DGAT1, PDAT1, and PDAT2 had significant effects on seed oil phenotype. Overall, this study indicated the existence of unique PDAT enzymes from flax that are able to preferentially catalyze the synthesis of TAG containing ALA acyl moieties. The identified LuPDATs may have practical applications for increasing the accumulation of ALA and other polyunsaturated fatty acids in oilseeds for food and industrial applications.

Mercuric chloride induces autoantibodies against U3 small nuclear ribonucleoprotein in susceptible mice.

PubMed Central

Reuter, R; Tessars, G; Vohr, H W; Gleichmann, E; Lührmann, R

1989-01-01

Autoantibodies to nucleolar components are a common serological feature of patients suffering from scleroderma, a collagen vascular autoimmune disease. While animal models, which spontaneously develop abundant anti-nucleolar antibodies, have not yet been described, high titers of such antibodies may be induced by treating susceptible strains of mice with mercuric chloride. We have identified the nucleolar autoantigen against which the HgCl2-induced IgG autoantibodies from mice of strain B10.S are directed. It is a protein with an apparent molecular mass of 36 kDa and a pI value of approximately 8.6, which is associated with the nucleolar small nuclear RNA U3, and by these criteria must be identical with a polypeptide called fibrillarin. It is striking that scleroderma patients spontaneously produce autoantibodies against the same U3 ribonucleoprotein (RNP). The HgCl2-induced murine and the scleroderma-specific human anti-U3 RNP autoantibodies were indistinguishable in their reactivities toward fibrillarin. They further resemble each other insofar as both recognize epitopes on the 36-kDa protein, which have been highly conserved throughout evolution. Our results provide a basis to investigate at the molecular level whether similar immunoregulatory dysfunctions may lead to the preferential anti-U3 RNP autoantibody production in the animal model and in scleroderma patients. Images PMID:2521387

Detoxification of diphenyl ether herbicide lactofen by Bacillus sp. Za and enantioselective characteristics of an esterase gene lacE.

PubMed

Zhang, Jing; Lu, Luyao; Chen, Feng; Chen, Lingling; Yin, Jingang; Huang, Xing

2018-01-05

A bacterial strain Za capable of degrading diphenyl ether herbicide lactofen was isolated and identified as Bacillus sp. This strain could degrade 94.8% of 50mgL -1 lactofen after 4days of inoculation in flasks. It was revealed that lactofen was initially hydrolyzed to desethyl lactofen, which was further transformed to acifluorfen, followed by the reduction of the nitro group to yield aminoacifluorfen. The phytotoxicity of the transformed product aminoacifluorfen to maize was decreased significantly compared with the lactofen. A gene lacE, encoding an esterase responsible for lactofen hydrolysis to desethyl lactofen and acifluorfen continuously, was cloned from Bacillus sp. Za. The deduced amino acid belonging to the esterase family VII contained a typical Ser-His-Asp/Glu catalytic triad and the conserved motifs GXSXG. The purified recombinant protein LacE displayed maximal esterase activity at 40°C and pH 7.0. Additionally, LacE had broad substrate specificity and was capable of hydrolyzing p-nitrophenyl esters. The enantioselectivity of LacE during lactofen degradation was further studied, and the results indicated that the (S)-(+)-lactofen was degraded faster than the (R)-(-)-lactofen, which could illustrate the reported phenomenon that (S)-(+)-lactofen was preferentially degraded in soil and sediment. Copyright © 2017 Elsevier B.V. All rights reserved.

A computational search for lipases that can preferentially hydrolyze long-chain omega-3 fatty acids from fish oil triacylglycerols.

PubMed

Kamal, Md Zahid; Barrow, Colin J; Rao, Nalam Madhusudhana

2015-04-15

Consumption of long-chain omega-3 fatty acids is known to decrease the risk of major cardiovascular events. Lipases, a class of triacylglycerol hydrolases, have been extensively tested to concentrate omega-3 fatty acids from fish oils, under mild enzymatic conditions. However, no lipases with preference for omega-3 fatty acids selectivity have yet been discovered or developed. In this study we performed an exhaustive computational study of substrate-lipase interactions by docking, both covalent and non-covalent, for 38 lipases with a large number of structured triacylglycerols containing omega-3 fatty acids. We identified some lipases that have potential to preferentially hydrolyze omega-3 fatty acids from structured triacylglycerols. However omega-3 fatty acid preferences were found to be modest. Our study provides an explanation for absence of reports of lipases with omega-3 fatty acid hydrolyzing ability and suggests methods for developing these selective lipases. Copyright © 2014 Elsevier Ltd. All rights reserved.

The large-scale investigation of gene expression in Leymus chinensis stigmas provides a valuable resource for understanding the mechanisms of poaceae self-incompatibility.

PubMed

Zhou, Qingyuan; Jia, Junting; Huang, Xing; Yan, Xueqing; Cheng, Liqin; Chen, Shuangyan; Li, Xiaoxia; Peng, Xianjun; Liu, Gongshe

2014-05-26

Many Poaceae species show a gametophytic self-incompatibility (GSI) system, which is controlled by at least two independent and multiallelic loci, S and Z. Until currently, the gene products for S and Z were unknown. Grass SI plant stigmas discriminate between pollen grains that land on its surface and support compatible pollen tube growth and penetration into the stigma, whereas recognizing incompatible pollen and thus inhibiting pollination behaviors. Leymus chinensis (Trin.) Tzvel. (sheepgrass) is a Poaceae SI species. A comprehensive analysis of sheepgrass stigma transcriptome may provide valuable information for understanding the mechanism of pollen-stigma interactions and grass SI. The transcript abundance profiles of mature stigmas, mature ovaries and leaves were examined using high-throughput next generation sequencing technology. A comparative transcriptomic analysis of these tissues identified 1,025 specifically or preferentially expressed genes in sheepgrass stigmas. These genes contained a significant proportion of genes predicted to function in cell-cell communication and signal transduction. We identified 111 putative transcription factors (TFs) genes and the most abundant groups were MYB, C2H2, C3H, FAR1, MADS. Comparative analysis of the sheepgrass, rice and Arabidopsis stigma-specific or preferential datasets showed broad similarities and some differences in the proportion of genes in the Gene Ontology (GO) functional categories. Potential SI candidate genes identified in other grasses were also detected in the sheepgrass stigma-specific or preferential dataset. Quantitative real-time PCR experiments validated the expression pattern of stigma preferential genes including homologous grass SI candidate genes. This study represents the first large-scale investigation of gene expression in the stigmas of an SI grass species. We uncovered many notable genes that are potentially involved in pollen-stigma interactions and SI mechanisms, including genes encoding receptor-like protein kinases (RLK), CBL (calcineurin B-like proteins) interacting protein kinases, calcium-dependent protein kinase, expansins, pectinesterase, peroxidases and various transcription factors. The availability of a pool of stigma-specific or preferential genes for L. chinensis offers an opportunity to elucidate the mechanisms of SI in Poaceae.

Specific injuries induced by the practice of trampoline, tumbling and acrobatic gymnastics.

PubMed

Grapton, Xavier; Lion, Alexis; Gauchard, Gérome C; Barrault, Denys; Perrin, Philippe P

2013-02-01

The recreational and competitive practice of acrobatic sports, that is, trampoline, tumbling and acrobatic gymnastics (ACRO), is growing rapidly around the world. Many studies described the injuries affecting young artistic gymnasts, but only few concerned acrobatic sports. During a 5-year period, 357 traumatic events were collected in young acrobats practicing trampoline, tumbling or ACRO. Accident characteristics, level of expertise and training, injury location (upper limb, spine and lower limb), type of tissue injured (bone, cartilage, muscle, ligament and tendon) and provoking factors (intrinsic/behavioural and extrinsic) were investigated. Acrobats of national and international levels were mostly injured. Injuries occurring in acrobatic sports concerned predominantly the lower limbs and concerned in this body part mainly damages to ligaments. Forearm and knee injuries were preferentially related to trampoline. Ankle injuries were preferentially related to tumbling. Wrist injuries were preferentially related to ACRO. Upper limb bone damage and upper limb tendon damage were preferentially related to trampoline and ACRO, respectively. Intrinsic/behavioural factors were the main injury determinant in the three acrobatic sports. The main injuries in acrobatic sports (i.e. lower limbs) are similar to those observed in artistic gymnastics. Specific injuries may result from falls and incomplete and/or erroneous figure's landing and may also depend to the type of the landing surface. II.

Estrogen regulates the rate of bone turnover but bone balance in ovariectomized rats is modulated by prevailing mechanical strain

NASA Technical Reports Server (NTRS)

Westerlind, K. C.; Wronski, T. J.; Ritman, E. L.; Luo, Z. P.; An, K. N.; Bell, N. H.; Turner, R. T.

1997-01-01

Estrogen deficiency induced bone loss is associated with increased bone turnover in rats and humans. The respective roles of increased bone turnover and altered balance between bone formation and bone resorption in mediating estrogen deficiency-induced cancellous bone loss was investigated in ovariectomized rats. Ovariectomy resulted in increased bone turnover in the distal femur. However, cancellous bone was preferentially lost in the metaphysis, a site that normally experiences low strain energy. No bone loss was observed in the epiphysis, a site experiencing higher strain energy. The role of mechanical strain in maintaining bone balance was investigated by altering the strain history. Mechanical strain was increased and decreased in long bones of ovariectomized rats by treadmill exercise and functional unloading, respectively. Functional unloading was achieved during orbital spaceflight and following unilateral sciatic neurotomy. Increasing mechanical loading reduced bone loss in the metaphysis. In contrast, decreasing loading accentuated bone loss in the metaphysis and resulted in bone loss in the epiphysis. Finally, administration of estrogen to ovariectomized rats reduced bone loss in the unloaded and prevented loss in the loaded limb following unilateral sciatic neurotomy in part by reducing indices of bone turnover. These results suggest that estrogen regulates the rate of bone turnover, but the overall balance between bone formation and bone resorption is influenced by prevailing levels of mechanical strain.

Potential prebiotic properties of cashew apple (Anacardium occidentale L.) agro-industrial byproduct on Lactobacillus species.

PubMed

Duarte, Francisca Nayara Dantas; Rodrigues, Jéssica Bezerra; da Costa Lima, Maiara; Lima, Marcos Dos Santos; Pacheco, Maria Teresa Bertoldo; Pintado, Maria Manuela Estevez; de Souza Aquino, Jailane; de Souza, Evandro Leite

2017-08-01

The prebiotic effects of a cashew apple (Anacardium occidentale L.) agro-industrial byproduct powder (CAP) on different potentially probiotic Lactobacillus strains, namely Lactobacillus acidophilus LA-05, Lactobacillus casei L-26 and Lactobacillus paracasei L-10, were assessed using in vitro experimental models. Accordingly, the growth of the Lactobacillus strains when cultivated in a broth containing CAP (20 or 30 g L -1 ), glucose (20 g L -1 ) or fructooligosaccharides (FOS) (20 g L -1 ) was monitored over 48 h; the prebiotic activity scores of CAP were determined; and the changes in pH values, production of organic acids and consumption of sugars in growth media were verified. During the 48-h cultivation, similar viable cell counts were observed for the Lactobacillus strains grown in the different media tested. The CAP presented positive prebiotic activity scores toward all the tested Lactobacillus strains, indicating a desirable selective fermentable activity relative to enteric organisms. The cultivation of the Lactobacillus strains in broth containing glucose, FOS or CAP resulted in high viable cell counts, a decreased pH, the production of organic acids and the consumption of sugars over time, revealing intense bacterial metabolic activity. The CAP exerts potential prebiotic effects on different potentially probiotic Lactobacillus strains and should be an added-value ingredient for the food industry. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Adsorption of aflatoxin B1, zearalenone and ochratoxin A by microorganisms isolated from Kefir grains.

PubMed

Taheur, Fadia Ben; Fedhila, Kais; Chaieb, Kamel; Kouidhi, Bochra; Bakhrouf, Amina; Abrunhosa, Luís

2017-06-19

A strategy to reduce the deleterious effects of mycotoxins is to use dietary supplements that contain microorganisms that bind mycotoxins and decrease their gastrointestinal absorption. Novel strains were isolated from a Kefir culture and assessed for their mycotoxin adsorption and biotransformation ability. The most active strains were identified using DNA sequencing, and the stability of microorganism/mycotoxin complexes was evaluated using buffer solutions to simulate the pH conditions in the gastrointestinal tract. Our results showed that the microorganism consortium of Kefir grains adsorbed 82 to 100% of aflatoxin B1 (AFB1), zearalenone (ZEA) and ochratoxin A (OTA) when cultivated in milk. The main strains that were capable of mycotoxin adsorption were identified as Lactobacillus kefiri, Kazachstania servazzii and Acetobacter syzygii. The strain L. kefiri KFLM3 was the most active, adsorbing 80 to 100% of the studied mycotoxins when cultivated in milk. Nonetheless, the strain K. servazzii KFGY7 retained more mycotoxin after the desorption experiments (65, 69 and 67% for AFB1, OTA and ZEA, respectively). These findings suggest that Kefir consumption may help to reduce gastrointestinal absorption of these mycotoxins and consequently reduce their toxic effects. The isolated strains may be of interest for the development of fermented dairy products for human consumption that have a new probiotic characteristic, the adsorption of mycotoxins. Copyright © 2017 Elsevier B.V. All rights reserved.

Prevalence and characterization of multidrug-resistant (type ACSSuT) Salmonella enterica serovar Typhimurium strains in isolates from four gosling farms and a hatchery farm.

PubMed

Yu, Chang-You; Chou, Shih-Jen; Yeh, Chia-Ming; Chao, Maw-Rong; Huang, Kwo-Ching; Chang, Yung-Fu; Chiou, Chien-Shun; Weill, Francois-Xavier; Chiu, Cheng-Hsun; Chu, Chi-Hong; Chu, Chishih

2008-02-01

Salmonella enterica serovar Typhimurium strains of phage types DT104 and U302 are often resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, and tetracycline (the ACSSuT resistance type) and are major zoonotic pathogens. Increased consumption of goose meat may enhance the risk of transferring S. enterica serovar Typhimurium and other enteric pathogens from geese to human due to the consumption of meats from infected geese or improper preparation of meats. Therefore, we characterized S. enterica serovar Typhimurium strains isolated from four goose farms (farms A, B, C, and D) and one hatchery farm (farm E) to determine the epidemic and genetic differences among them. Antibiotic susceptibility tests and multiplex PCR confirmed that 77.6% (52/67) of strains were ACSSuT strains isolated from farms A, C, and E. Antibiotic-susceptible strains were isolated mostly from farm B, and no strain was observed in farm D. All ACSSuT strains harbored a 94.7-kb virulence plasmid and contained one 1.1-kb conserved segment identical to that of Salmonella genomic island 1. Four genotypes were determined among these S. enterica serovar Typhimurium isolates by pulsed-field gel electrophoresis analysis of XbaI-digested DNA fragments. Most isolates (85.29%; 29/34) of major genotype Ib were ACSSuT strains isolated mainly from goslings of farm C and egg membranes of farm E, a hatchery farm, suggesting that S. enterica serovar Typhimurium strains in isolates from goslings might originate from its hatchery, from the egg membranes to the gosling fluff after hatching. Multiple phage types, types 8, 12, U283, DT104, and U302, were identified. In conclusion, geese were a reservoir of diverse multidrug-resistant (type ACSSuT) S. enterica serovar Typhimurium strains, and each farm was colonized with genetically closely related S. enterica serovar Typhimurium strains.

Introduction to the Special Issue: Precarious Solidarity-Preferential Access in Canadian Health Care.

PubMed

Reid, Lynette

2017-06-01

Systems of universal health coverage may aspire to provide care based on need and not ability to pay; the complexities of this aspiration (conceptual, practical, and ethical) call for normative analysis. This special issue arises in the wake of a judicial inquiry into preferential access in the Canadian province of Alberta, the Vertes Commission. I describe this inquiry and set out a taxonomy of forms of differential and preferential access. Papers in this special issue focus on the conceptual specification of health system boundaries (the concept of medical need) and on the normative questions raised by complex models of funding and delivery of care, where patients, providers, and services cross system boundaries.

Lithium-induced effects on adult hippocampal neurogenesis are topographically segregated along the dorso-ventral axis of stressed mice.

PubMed

O'Leary, Olivia F; O'Connor, Richard M; Cryan, John F

2012-01-01

Adult hippocampal neurogenesis is an important process in the regulation of cognition, stress responsivity, and sensitivity to antidepressant and mood stabiliser drugs. Increasing evidence suggests that the hippocampus is functionally divided along its axis with the ventral hippocampus (vHi) playing a preferential role in stress- and anxiety-related processes, while the dorsal hippocampus (dHi) is crucial for spatial learning and memory. However, it is currently unclear whether stress or the medications used to treat stress-related disorders, preferentially affect neurogenesis in the vHi rather than dHi. The aim of this study was to determine whether the mood stabiliser, lithium, preferentially affects cell proliferation and survival in the vHi rather than dHi under stress conditions. To this end, mice of the stress-sensitive strain, BALB/c, underwent chronic exposure to immobilisation stress plus lithium treatment (0.2% lithium-supplemented diet), and the rates of cell proliferation and survival were compared in the dHi and vHi. Lithium preferentially increased cell proliferation in the vHi under stress conditions only. This increase in cell proliferation was secondary to reductions in the survival of newly-born cells. Moreover, lithium-induced decreases in cell survival in the vHi were only observed under stress conditions. Taken together, the data suggest that the turnover of newly-born cells in response to chronic stress and lithium treatment occurs predominantly in the vHi rather than the dHi. This article is part of a Special Issue entitled 'Anxiety and Depression'. Copyright © 2011 Elsevier Ltd. All rights reserved.

Pulsed addition of HMF and furfural to batch-grown xylose-utilizing Saccharomyces cerevisiae results in different physiological responses in glucose and xylose consumption phase

PubMed Central

2013-01-01

Background Pretreatment of lignocellulosic biomass generates a number of undesired degradation products that can inhibit microbial metabolism. Two of these compounds, the furan aldehydes 5-hydroxymethylfurfural (HMF) and 2-furaldehyde (furfural), have been shown to be an impediment for viable ethanol production. In the present study, HMF and furfural were pulse-added during either the glucose or the xylose consumption phase in order to dissect the effects of these inhibitors on energy state, redox metabolism, and gene expression of xylose-consuming Saccharomyces cerevisiae. Results Pulsed addition of 3.9 g L-1 HMF and 1.2 g L-1 furfural during either the glucose or the xylose consumption phase resulted in distinct physiological responses. Addition of furan aldehydes in the glucose consumption phase was followed by a decrease in the specific growth rate and the glycerol yield, whereas the acetate yield increased 7.3-fold, suggesting that NAD(P)H for furan aldehyde conversion was generated by acetate synthesis. No change in the intracellular levels of NAD(P)H was observed 1 hour after pulsing, whereas the intracellular concentration of ATP increased by 58%. An investigation of the response at transcriptional level revealed changes known to be correlated with perturbations in the specific growth rate, such as protein and nucleotide biosynthesis. Addition of furan aldehydes during the xylose consumption phase brought about an increase in the glycerol and acetate yields, whereas the xylitol yield was severely reduced. The intracellular concentrations of NADH and NADPH decreased by 58 and 85%, respectively, hence suggesting that HMF and furfural drained the cells of reducing power. The intracellular concentration of ATP was reduced by 42% 1 hour after pulsing of inhibitors, suggesting that energy-requiring repair or maintenance processes were activated. Transcriptome profiling showed that NADPH-requiring processes such as amino acid biosynthesis and sulfate and nitrogen assimilation were induced 1 hour after pulsing. Conclusions The redox and energy metabolism were found to be more severely affected after pulsing of furan aldehydes during the xylose consumption phase than during glucose consumption. Conceivably, this discrepancy resulted from the low xylose utilization rate, hence suggesting that xylose metabolism is a feasible target for metabolic engineering of more robust xylose-utilizing yeast strains. PMID:24341320

Microbial characterization of probiotics--advisory report of the Working Group "8651 Probiotics" of the Belgian Superior Health Council (SHC).

PubMed

Huys, Geert; Botteldoorn, Nadine; Delvigne, Frank; De Vuyst, Luc; Heyndrickx, Marc; Pot, Bruno; Dubois, Jean-Jacques; Daube, Georges

2013-08-01

When ingested in sufficient numbers, probiotics are expected to confer one or more proven health benefits on the consumer. Theoretically, the effectiveness of a probiotic food product is the sum of its microbial quality and its functional potential. Whereas the latter may vary much with the body (target) site, delivery mode, human target population, and health benefit envisaged microbial assessment of the probiotic product quality is more straightforward. The range of stakeholders that need to be informed on probiotic quality assessments is extremely broad, including academics, food and biotherapeutic industries, healthcare professionals, competent authorities, consumers, and professional press. In view of the rapidly expanding knowledge on this subject, the Belgian Superior Health Council installed Working Group "8651 Probiotics" to review the state of knowledge regarding the methodologies that make it possible to characterize strains and products with purported probiotic activity. This advisory report covers three main steps in the microbial quality assessment process, i.e. (i) correct species identification and strain-specific typing of bacterial and yeast strains used in probiotic applications, (ii) safety assessment of probiotic strains used for human consumption, and (iii) quality of the final probiotic product in terms of its microbial composition, concentration, stability, authenticity, and labeling. © 2013 The Authors. Molecular Nutrition & Food Research published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stimulation of indigenous lactobacilli by fermented milk prepared with probiotic bacterium, Lactobacillus delbrueckii subsp. bulgaricus strain 2038, in the pigs.

PubMed

Ohashi, Yuji; Tokunaga, Makoto; Taketomo, Naoki; Ushida, Kazunari

2007-02-01

The aim of this study was to evaluate the effect of feeding yoghurt, prepared with Lactobacillus delbrueckii subsp. bulgaricus strain 2038, on indigenous lactobacilli in the pig cecum. Three female pigs fistulated at the cecum were fed 250 g of this yoghurt that contained over 10(11) colony-forming units of L. delbrueckii subsp. bulgaricus strain 2038 with their daily meal for 2 wk. The relative abundance and the composition of cecal lactobacilli was monitored by analysis of bacterial 16S rDNA with real time PCR and amplified bacterial rDNA restriction analysis using Lactobacillus-group specific primers, respectively, for 2 wk prior to, at the end of 2 wk of and 2 wk after the administration of this yoghurt. The relative abundance of lactobacilli was significantly increased by feeding yoghurt (p<0.01), although the bacterial 16S rDNA matching L. delbrueckii subsp. bulgaricus strain 2038 was not detected by amplified bacterial rDNA restriction analysis during this study. The number of operational taxonomic units (OTUs) detected was increased with feeding of the yoghurt in all pigs. At the same time, the estimated cell number of each OTU was increased with feeding of the yoghurt. It is demonstrated that continuous consumption of the probiotic lactobacilli will stimulate the growth of some indigenous lactobacilli and alter the composition of the lactobacilli.

Complete Genome Sequence of Plesiomonas shigelloides Type Strain NCTC10360

PubMed Central

Fazal, Mohammed-Abbas; Burnett, Edward; Deheer-Graham, Ana; Oliver, Karen; Holroyd, Nancy; Russell, Julie E.

2016-01-01

Plesiomonas shigelloides is a Gram-negative rod within the Enterobacteriaceae family. It is a gastrointestinal pathogen of increasing notoriety, often associated with diarrheal disease. P. shigelloides is waterborne, and infection is often linked to the consumption of seafood. Here, we describe the first complete genome for P. shigelloides type strain NCTC10360. PMID:27660796

Material specific lateralization of medial temporal lobe function: An fMRI investigation.

PubMed

Dalton, Marshall A; Hornberger, Michael; Piguet, Olivier

2016-03-01

The theory of material specific lateralization of memory function posits that left and right MTL regions are asymmetrically involved in mnemonic processing of verbal and nonverbal material respectively. Lesion and functional imaging (fMRI) studies provide robust evidence for a left MTL asymmetry in the verbal memory domain. Evidence for a right MTL/nonverbal asymmetry is not as robust. A handful of fMRI studies have investigated this issue but have generally utilised nonverbal stimuli which are amenable to semantic elaboration. This fMRI study aimed to investigate the neural correlates of recognition memory processing in 20 healthy young adults (mean age = 26 years) for verbal stimuli and nonverbal stimuli that were specifically designed to minimize verbalisation. Analyses revealed that the neural correlates of recognition memory processing for verbal and nonverbal stimuli were differentiable and asymmetrically recruited the left and right MTL respectively. The right perirhinal cortex and hippocampus were preferentially involved in successful recognition memory of items devoid of semantic information. In contrast, the left anterior hippocampus was preferentially involved in successful recognition memory of stimuli which contained semantic meaning. These results suggest that the left MTL is preferentially involved in mnemonic processing of verbal/semantic information. In contrast, the right MTL is preferentially involved in visual/non-semantic mnemonic processing. We propose that during development, the left MTL becomes specialised for verbal mnemonic processing due to its proximity with left lateralised cortical language processing areas while visual/non-semantic mnemonic processing gets 'crowded out' to become predominantly, but not completely, the domain of the right MTL. © 2015 Wiley Periodicals, Inc.

A probiotic dairy product containing L. gasseri CECT5714 and L. coryniformis CECT5711 induces immunological changes in children suffering from allergy.

PubMed

Martínez-Cañavate, Ana; Sierra, Saleta; Lara-Villoslada, Federico; Romero, Julio; Maldonado, José; Boza, Julio; Xaus, Jordi; Olivares, Mónica

2009-09-01

The increase in the prevalence of allergic diseases in children has been attributed to an unbalanced immune response probably due to environmental factors. The immunoregulatory properties of probiotic bacteria could balance the disequilibrium in the immune response causing the allergic response. The aim of this study was to evaluate the immunological effects of the consumption of a dairy product containing two probiotic strains in children suffering from allergy. A double-blinded, randomized, control comparative study was performed with 44 allergic children. Children were randomly distributed in two groups, a control Yogurt and a Probiotic group. Both groups daily consumed 200 ml of a dairy fermented product for 3 months. The Yogurt group consumed a conventional yogurt, whereas the Probiotic group consumed a similar dairy product where Lactobacillus bulgaricus was substituted by a mixture of Lactobacillus gasseri CECT5714 and Lactobacillus coryniformis CECT5711 (at least 10(6) cfu/g each strain). Intestinal and immunological parameters were measured in fecal and blood samples. The consumption of the probiotic product induced a significant decrease in the level of IgE in plasma (p = 0.03) and an increase in CD4(+)/CD25(+) T regulatory cells (p = 0.01). The decrease in IgE was accompanied by a significant increase in mucosal IgA (p = 0.01). However, changes in other effector cells potentially involved in allergic reactions such as eosinophiles, basophiles or other IgE+ cells were not detected. The consumption of the probiotic product also induced significant changes in innate response as a significant increase in natural killer cells was detected (p = 0.03). The daily consumption of a probiotic product containing L. gasseri CECT5714 and L. coryniformis CECT5711 for 3 months induces, in allergic children, beneficial effects on immune parameters involved in the allergic response such as a reduction of IgE in plasma and an increase in regulatory T cells. The probiotic product also enhanced innate and specific immune parameters that may improve the general health status of children.

Molecular characterization of infectious pancreatic necrosis virus strains isolated from the three types of salmonids farmed in Chile.

PubMed

Manríquez, René A; Vera, Tamara; Villalba, Melina V; Mancilla, Alejandra; Vakharia, Vikram N; Yañez, Alejandro J; Cárcamo, Juan G

2017-01-31

The infectious pancreatic necrosis virus (IPNV) causes significant economic losses in Chilean salmon farming. For effective sanitary management, the IPNV strains present in Chile need to be fully studied, characterized, and constantly updated at the molecular level. In this study, 36 Chilean IPNV isolates collected over 6 years (2006-2011) from Salmo salar, Oncorhynchus mykiss, and Oncorhynchus kisutch were genotypically characterized. Salmonid samples were obtained from freshwater, estuary, and seawater sources from central, southern, and the extreme-south of Chile (35° to 53°S). Sequence analysis of the VP2 gene classified 10 IPNV isolates as genogroup 1 and 26 as genogroup 5. Analyses indicated a preferential, but not obligate, relationship between genogroup 5 isolates and S. salar infection. Fifteen genogroup 5 and nine genogroup 1 isolates presented VP2 gene residues associated with high virulence (i.e. Thr, Ala, and Thr at positions 217, 221, and 247, respectively). Four genogroup 5 isolates presented an oddly long VP5 deduced amino acid sequence (29.6 kDa). Analysis of the VP2 amino acid motifs associated with clinical and subclinical infections identified the clinical fingerprint in only genogroup 5 isolates; in contrast, the genogroup 1 isolates presented sequences predominantly associated with the subclinical fingerprint. Predictive analysis of VP5 showed an absence of transmembrane domains and plasma membrane tropism signals. WebLogo analysis of the VP5 BH domains revealed high identities with the marine birnavirus Y-6 and Japanese IPNV strain E1-S. Sequence analysis for putative 25 kDa proteins, coded by the ORF between VP2 and VP4, exhibited three putative nuclear localization sequences and signals of mitochondrial tropism in two isolates. This study provides important advances in updating the characterizations of IPNV strains present in Chile. The results from this study will help in identifying epidemiological links and generating specific biotechnological tools for controlling IPNV outbreaks in Chilean salmon farming.

Modification of glucose import capacity in Escherichia coli: physiologic consequences and utility for improving DNA vaccine production

PubMed Central

2013-01-01

Background The bacterium Escherichia coli can be grown employing various carbohydrates as sole carbon and energy source. Among them, glucose affords the highest growth rate. This sugar is nowadays widely employed as raw material in industrial fermentations. When E. coli grows in a medium containing non-limiting concentrations of glucose, a metabolic imbalance occurs whose main consequence is acetate secretion. The production of this toxic organic acid reduces strain productivity and viability. Solutions to this problem include reducing glucose concentration by substrate feeding strategies or the generation of mutant strains with impaired glucose import capacity. In this work, a collection of E. coli strains with inactive genes encoding proteins involved in glucose transport where generated to determine the effects of reduced glucose import capacity on growth rate, biomass yield, acetate and production of an experimental plasmid DNA vaccine (pHN). Results A group of 15 isogenic derivatives of E. coli W3110 were generated with single and multiple deletions of genes encoding glucose, mannose, beta-glucoside, maltose and N-acetylglucosamine components of the phosphoenolpyruvate:sugar phosphotransferase system (PTS), as well as the galactose symporter and the Mgl galactose/glucose ABC transporter. These strains were characterized by growing them in mineral salts medium supplemented with 2.5 g/L glucose. Maximum specific rates of glucose consumption (qs) spanning from 1.33 to 0.32 g/g h were displayed by the group of mutants and W3110, which resulted in specific growth rates ranging from 0.65-0.18 h-1. Acetate accumulation was reduced or abolished in cultures with all mutant strains. W3110 and five selected mutant derivatives were transformed with pHN. A 3.2-fold increase in pHN yield on biomass was observed in cultures of a mutant strain with deletion of genes encoding the glucose and mannose PTS components, as well as Mgl. Conclusions The group of E. coli mutants generated in this study displayed a reduction or elimination of overflow metabolism and a linear correlation between qs and the maximum specific growth rate as well as the acetate production rate. By comparing DNA vaccine production parameters among some of these mutants, it was possible to identify a near-optimal glucose import rate value for this particular application. The strains employed in this study should be a useful resource for studying the effects of different predefined qs values on production capacity for various biotechnological products. PMID:23638701

Cashew apple bagasse as a source of sugars for ethanol production by Kluyveromyces marxianus CE025.

PubMed

Rocha, Maria Valderez Ponte; Rodrigues, Tigressa Helena Soares; Melo, Vania M M; Gonçalves, Luciana R B; de Macedo, Gorete Ribeiro

2011-08-01

The potential of cashew apple bagasse as a source of sugars for ethanol production by Kluyveromyces marxianus CE025 was evaluated in this work. This strain was preliminarily cultivated in a synthetic medium containing glucose and xylose and was able to produce ethanol and xylitol at pH 4.5. Next, cashew apple bagasse hydrolysate (CABH) was prepared by a diluted sulfuric acid pretreatment and used as fermentation media. This hydrolysate is rich in glucose, xylose, and arabinose and contains traces of formic acid and acetic acid. In batch fermentations of CABH at pH 4.5, the strain produced only ethanol. The effects of temperature on the kinetic parameters of ethanol fermentation by K. marxianus CE025 using CABH were also evaluated. Maximum specific growth rate (μ(max)), overall yields of ethanol based on glucose consumption [Formula: see text] and based on glucose + xylose consumption (Y ( P/S )), overall yield of ethanol based on biomass (Y ( P/X )), and ethanol productivity (P (E)) were determined as a function of temperature. Best results of ethanol production were achieved at 30°C, which is also quite close to the optimum temperature for the formation of biomass. The process yielded 12.36 ± 0.06 g l(-1) of ethanol with a volumetric production rate of 0.257 ± 0.002 g l(-1) h(-1) and an ethanol yield of 0.417 ± 0.003 g g(-1) glucose.

Differential effects of ethanol and other inducers of drug metabolism on the two forms of hamster liver microsomal aniline hydroxylase.

PubMed

McCoy, G D

1980-03-01

The aniline hydroxylase activity of microsomes isolated from hamster liver can be differentiated kinetically into high affinity (low K(m), form I) and low affinity (high K(m), form II) forms. Microsomes isolated from uninduced animals contain slightly more form I activity. The activity of the low affinity form (form II) is preferentially enhanced by Aroclor or 3-methylcholanthrene treatment, while phenobarbital treatment increases the activity of both forms. Chronic ethanol consumption results in enhancement of only the high affinity form (form I).

Epidemiology and genetic diversity of Taenia asiatica: a systematic review.

PubMed

Ale, Anita; Victor, Bjorn; Praet, Nicolas; Gabriël, Sarah; Speybroeck, Niko; Dorny, Pierre; Devleesschauwer, Brecht

2014-01-22

Taenia asiatica has made a remarkable journey through the scientific literature of the past 50 years, starting with the paradoxical observation of high prevalences of T. saginata-like tapeworms in non-beef consuming populations, to the full description of its mitochondrial genome. Experimental studies conducted in the 1980s and 1990s have made it clear that the life cycle of T. asiatica is comparable to that of T. saginata, except for pigs being the preferential intermediate host and liver the preferential location of the cysts. Whether or not T. asiatica can cause human cysticercosis, as is the case for Taenia solium, remains unclear. Given the specific conditions needed to complete its life cycle, in particular the consumption of raw or poorly cooked pig liver, the transmission of T. asiatica shows an important ethno-geographical association. So far, T. asiatica has been identified in Taiwan, South Korea, Indonesia, the Philippines, Thailand, south-central China, Vietnam, Japan and Nepal. Especially this last observation indicates that its distribution is not restricted to South-East-Asia, as was thought so far. Indeed, the molecular tools developed over the last 20 years have made it increasingly possible to differentiate T. asiatica from other taeniids. Such tools also indicated that T. asiatica is related more closely to T. saginata than to T. solium, feeding the debate on its taxonomic status as a separate species versus a subspecies of T. saginata. Furthermore, the genetic diversity within T. asiatica appears to be very minimal, indicating that this parasite may be on the verge of extinction. However, recent studies have identified potential hybrids between T. asiatica and T. saginata, reopening the debate on the genetic diversity of T. asiatica and its status as a separate species.

Epidemiology and genetic diversity of Taenia asiatica: a systematic review

PubMed Central

2014-01-01

Taenia asiatica has made a remarkable journey through the scientific literature of the past 50 years, starting with the paradoxical observation of high prevalences of T. saginata-like tapeworms in non-beef consuming populations, to the full description of its mitochondrial genome. Experimental studies conducted in the 1980s and 1990s have made it clear that the life cycle of T. asiatica is comparable to that of T. saginata, except for pigs being the preferential intermediate host and liver the preferential location of the cysts. Whether or not T. asiatica can cause human cysticercosis, as is the case for Taenia solium, remains unclear. Given the specific conditions needed to complete its life cycle, in particular the consumption of raw or poorly cooked pig liver, the transmission of T. asiatica shows an important ethno-geographical association. So far, T. asiatica has been identified in Taiwan, South Korea, Indonesia, the Philippines, Thailand, south-central China, Vietnam, Japan and Nepal. Especially this last observation indicates that its distribution is not restricted to South-East-Asia, as was thought so far. Indeed, the molecular tools developed over the last 20 years have made it increasingly possible to differentiate T. asiatica from other taeniids. Such tools also indicated that T. asiatica is related more closely to T. saginata than to T. solium, feeding the debate on its taxonomic status as a separate species versus a subspecies of T. saginata. Furthermore, the genetic diversity within T. asiatica appears to be very minimal, indicating that this parasite may be on the verge of extinction. However, recent studies have identified potential hybrids between T. asiatica and T. saginata, reopening the debate on the genetic diversity of T. asiatica and its status as a separate species. PMID:24450957

What are the governing processes during low-flows in a chalk catchment?

NASA Astrophysics Data System (ADS)

Lubega Musuuza, Jude; Coxon, Gemma; Hutton, Chris; Howden, Nicholas; Woods, Ross; Freer, Jim; Wagener, Thorsten

2016-04-01

Low flows are important because they lead to the prioritisation of different consumptive water usages, imposition of restrictions and bans, raising of water tariffs and higher production costs to industry. The partitioning of precipitation into evaporation, storage and runoff depends on the local variability in meteorological variables and site-specific characteristics e.g., topography, soils and vegetation. The response of chalk catchments to meteorological forcing especially precipitation is of particular interest because of the preferential flow through the weathered formation. This makes the observed stream discharge groundwater-dominated and hence, out of phase with precipitation. One relevant question is how sensitive the low flow characteristics of such a chalk catchment is to changes in climate and land use. It is thus important to understand all the factors that control low stream discharge periods. In this study we present the results from numerical sensitivity analysis experiments performed with a detailed physically-based model on the Kennet, a sub-catchment of the River Thames, in the UK during the historical drought years of the 1970's.

An Evidence-Based Framework for Strengthening Exercises to Prevent Hamstring Injury.

PubMed

Bourne, Matthew N; Timmins, Ryan G; Opar, David A; Pizzari, Tania; Ruddy, Joshua D; Sims, Casey; Williams, Morgan D; Shield, Anthony J

2018-02-01

Strength training is a valuable component of hamstring strain injury prevention programmes; however, in recent years a significant body of work has emerged to suggest that the acute responses and chronic adaptations to training with different exercises are heterogeneous. Unfortunately, these research findings do not appear to have uniformly influenced clinical guidelines for exercise selection in hamstring injury prevention or rehabilitation programmes. The purpose of this review was to provide the practitioner with an evidence-base from which to prescribe strengthening exercises to mitigate the risk of hamstring injury. Several studies have established that eccentric knee flexor conditioning reduces the risk of hamstring strain injury when compliance is adequate. The benefits of this type of training are likely to be at least partly mediated by increases in biceps femoris long head fascicle length and improvements in eccentric knee flexor strength. Therefore, selecting exercises with a proven benefit on these variables should form the basis of effective injury prevention protocols. In addition, a growing body of work suggests that the patterns of hamstring muscle activation diverge significantly between different exercises. Typically, relatively higher levels of biceps femoris long head and semimembranosus activity have been observed during hip extension-oriented movements, whereas preferential semitendinosus and biceps femoris short head activation have been reported during knee flexion-oriented movements. These findings may have implications for targeting specific muscles in injury prevention programmes. An evidence-based approach to strength training for the prevention of hamstring strain injury should consider the impact of exercise selection on muscle activation, and the effect of training interventions on hamstring muscle architecture, morphology and function. Most importantly, practitioners should consider the effect of a strength training programme on known or proposed risk factors for hamstring injury.

Identification and Characterization of Intercritical Heat-Affected Zone in As-Welded Grade 91 Weldment

NASA Astrophysics Data System (ADS)

Wang, Yiyu; Kannan, Rangasayee; Li, Leijun

2016-12-01

A metallurgical method is proposed for locating the intercritical heat-affected zone in the as-welded Grade 91 steel. New austenitic grains, preferentially formed along the original prior austenite grain boundaries, are characterized to contain finer M23C6 carbides and higher strain levels than the original prior austenite grains. Kurdjumov-Sachs Group 1 variant pairs, with a low misorientation of 7 deg within a martensitic block, are identified as the dominant variants in the new PAGs.

Low cycle fatigue of MAR-M 200 single crystals at 760 and 870 deg C

NASA Technical Reports Server (NTRS)

Milligan, W. W.; Jayaraman, N.; Bill, R. C.

1984-01-01

Fully reversed low cycle fatigue tests were conducted on single crystals of the nickel-base superalloys Mar-M 200 at 760 C and 870 C. At 760 C, planar slip (octahedral) lead to orientation-dependent strain hardening and cyclic lives. Multiple slip crystals strain hardened the most, resulting in relatively high stress ranges and low lives. Single slip crystals strain hardened the least, resulting in relatively low stress ranges and higher lives. A preferential crack initiation site which was related to slip plane geometry was observed in single slip orientated crystals. At 870 C, the trends were quite different, and the slip character was much more homogeneous. As the tensile axis orientation deviated from 001 , the stress ranges increased and the cyclic lives decreased. Two possible mechanisms were proposed to explain the behavior: one is based on Takeuchi and Kuramoto's cube cross-slip model, and the other is based on orientation-dependent creep rates.

Effect of the expansion associated with the plutonium α-β-γ phase transitions on storage can integrity

NASA Astrophysics Data System (ADS)

Spearing, Dane R.; Veirs, D. Kirk; Prenger, F. Coyne

2001-11-01

The effects of the volume expansion of plutonium metal through the α-β and β-γ phase transitions on a stainless steel storage container were examined. A cylindrical plutonium ingot was placed in the axial center of an annealed stainless steel cylinder and thermally cycled until a steady state in the strain response of the cylinder was reached. The average plastic hoop strain was 1.47% and 1.55% after six and four cycles through the α-β and α-β-γ phase transitions, respectively. Elastic strain was ˜0.2%, indicating a 8.96 MPa back pressure on the Pu ingot. This is an order of magnitude less than the compressive yield strength of α- and β-Pu at the transition temperature. Metallographic analyses indicate that anisotropic expansion of the Pu ingot is due to preferentially oriented grain growth of the β-Pu along the axial direction due to stress applied by the steel cylinder during the α-β phase transition.

In vitro evaluation of cross-strain inhibitory effects of IgY polyclonal antibody against H. pylori.

PubMed

Solhi, Roya; Alebouyeh, Masoud; Khafri, Abolfazl; Rezaeifard, Morteza; Aminian, Mahdi

2017-09-01

The present study aimed to evaluate in vitro cross-strain inhibitory effects of IgY polyclonal antibody on both growth and urease enzyme of four local strains of H. pylori. Leghorn chickens were immunized with whole cells of four different strains of H. pylori, separately. Rising of specific IgY was detected by ELISA. The IgY purified using polyethylene glycol method and the purity was evaluated by SDS-PAGE and Western blotting. Each strain was treated with its own-specific and also other strain-specific IgYs. The strain-specific IgY could inhibit the growth of specific strains by 49-72% and also other different strains of H. pylori by 29-86%. Our findings revealed that strain-specific IgY could inhibit urease activity of its own by 64-72% and other different strains by 49-79%. These findings confirmed strain-specific and also cross-strain inhibitory effects of the IgY polyclonal antibody on both growth and urease activity of H. pylori. Copyright © 2017 Elsevier Ltd. All rights reserved.

The carbon consumption pattern of the spoilage yeast Brettanomyces bruxellensis in synthetic wine-like medium.

PubMed

Smith, Brendan D; Divol, Benoit

2018-08-01

The wine matrix contains limited carbon compounds to sustain microbial life. Brettanomyces bruxellensis is one of very few yeast species that has adapted to this environment. Indeed, the presence of growth-inhibiting compounds and conditions do not prevent its proliferation. Literature regarding the nutritional requirements of this yeast is surprisingly poor, given the observation that B. bruxellensis produces biomass with apparently less nutrients than other yeasts. In this study, various carbon sources were screened in a synthetic wine medium, under anaerobic and semi-aerobic growth conditions, in order to determine which compounds B. bruxellensis assimilates. Slight differences were observed between strains but overall, B. bruxellensis produced biomass from limited nutrients consumed in a specific order regardless of the oxygen conditions. Upon initial consumption of the simple sugars, B. bruxellensis was able to remain viable, by concurrently utilising ethanol (only in the presence of oxygen) and malic acid. Although initially beneficial, oxygen was found detrimental in the long term. Formation of volatile phenols occurred during the consumption of the sugars but not as a mechanism to help correct the redox imbalance. The study confirms that B. bruxellensis is able to survive using limited amount of nutrients, making this yeast a challenge for winemakers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spodoptera frugiperda (Lepidoptera: Noctuidae) host-plant variants: two host strains or two distinct species?

PubMed

Dumas, Pascaline; Legeai, Fabrice; Lemaitre, Claire; Scaon, Erwan; Orsucci, Marion; Labadie, Karine; Gimenez, Sylvie; Clamens, Anne-Laure; Henri, Hélène; Vavre, Fabrice; Aury, Jean-Marc; Fournier, Philippe; Kergoat, Gael J; d'Alençon, Emmanuelle

2015-06-01

The moth Spodoptera frugiperda is a well-known pest of crops throughout the Americas, which consists of two strains adapted to different host-plants: the first feeds preferentially on corn, cotton and sorghum whereas the second is more associated with rice and several pasture grasses. Though morphologically indistinguishable, they exhibit differences in their mating behavior, pheromone compositions, and show development variability according to the host-plant. Though the latter suggest that both strains are different species, this issue is still highly controversial because hybrids naturally occur in the wild, not to mention the discrepancies among published results concerning mating success between the two strains. In order to clarify the status of the two host-plant strains of S. frugiperda, we analyze features that possibly reflect the level of post-zygotic isolation: (1) first generation (F1) hybrid lethality and sterility; (2) patterns of meiotic segregation of hybrids in reciprocal second generation (F2), as compared to the meiosis of the two parental strains. We found a significant reduction of mating success in F1 in one direction of the cross and a high level of microsatellite markers showing transmission ratio distortion in the F2 progeny. Our results support the existence of post-zygotic reproductive isolation between the two laboratory strains and are in accordance with the marked level of genetic differentiation that was recovered between individuals of the two strains collected from the field. Altogether these results provide additional evidence in favor of a sibling species status for the two strains.

Strain-controlled skyrmion creation and propagation in ferroelectric/ferromagnetic hybrid wires

NASA Astrophysics Data System (ADS)

Li, Zhi; Zhang, Youguang; Huang, Yangqi; Wang, Chengxiang; Zhang, Xichao; Liu, Yan; Zhou, Yan; Kang, Wang; Koli, Shradha Chandrashekhar; Lei, Na

2018-06-01

The control of magnetic skyrmion creation and pinning through strain is studied by micromagnetic simulations. A single stable skyrmion can be created by a vertical strain pulse on Pd/Fe/Ir hybrid structure on Pb(Zr1-xTix)O3 nanowire with -1.8 V pulse voltage from 1.2 ns to 2.0 ns. Then the skyrmion is pinned by the vertical strain independent of the polarity during its propagation in the wire driven by the current. The proposed device integrates strain-controlled skyrmion creation and pinning in a single nanowire structure, which would open a new route for skyrmion-based memory and logic devices with ultra-low power consumption.

Combining Evidence of Preferential Gene-Tissue Relationships from Multiple Sources

PubMed Central

Guo, Jing; Hammar, Mårten; Öberg, Lisa; Padmanabhuni, Shanmukha S.; Bjäreland, Marcus; Dalevi, Daniel

2013-01-01

An important challenge in drug discovery and disease prognosis is to predict genes that are preferentially expressed in one or a few tissues, i.e. showing a considerably higher expression in one tissue(s) compared to the others. Although several data sources and methods have been published explicitly for this purpose, they often disagree and it is not evident how to retrieve these genes and how to distinguish true biological findings from those that are due to choice-of-method and/or experimental settings. In this work we have developed a computational approach that combines results from multiple methods and datasets with the aim to eliminate method/study-specific biases and to improve the predictability of preferentially expressed human genes. A rule-based score is used to merge and assign support to the results. Five sets of genes with known tissue specificity were used for parameter pruning and cross-validation. In total we identify 3434 tissue-specific genes. We compare the genes of highest scores with the public databases: PaGenBase (microarray), TiGER (EST) and HPA (protein expression data). The results have 85% overlap to PaGenBase, 71% to TiGER and only 28% to HPA. 99% of our predictions have support from at least one of these databases. Our approach also performs better than any of the databases on identifying drug targets and biomarkers with known tissue-specificity. PMID:23950964

Transgenic zebrafish reveal tissue-specific differences in estrogen signaling in response to environmental water samples.

PubMed

Gorelick, Daniel A; Iwanowicz, Luke R; Hung, Alice L; Blazer, Vicki S; Halpern, Marnie E

2014-04-01

Environmental endocrine disruptors (EEDs) are exogenous chemicals that mimic endogenous hormones such as estrogens. Previous studies using a zebrafish transgenic reporter demonstrated that the EEDs bisphenol A and genistein preferentially activate estrogen receptors (ERs) in the larval heart compared with the liver. However, it was not known whether the transgenic zebrafish reporter was sensitive enough to detect estrogens from environmental samples, whether environmental estrogens would exhibit tissue-specific effects similar to those of BPA and genistein, or why some compounds preferentially target receptors in the heart. We tested surface water samples using a transgenic zebrafish reporter with tandem estrogen response elements driving green fluorescent protein expression (5xERE:GFP). Reporter activation was colocalized with tissue-specific expression of ER genes by RNA in situ hybridization. We observed selective patterns of ER activation in transgenic fish exposed to river water samples from the Mid-Atlantic United States, with several samples preferentially activating receptors in embryonic and larval heart valves. We discovered that tissue specificity in ER activation was due to differences in the expression of ER subtypes. ERα was expressed in developing heart valves but not in the liver, whereas ERβ2 had the opposite profile. Accordingly, subtype-specific ER agonists activated the reporter in either the heart valves or the liver. The use of 5xERE:GFP transgenic zebrafish revealed an unexpected tissue-specific difference in the response to environmentally relevant estrogenic compounds. Exposure to estrogenic EEDs in utero was associated with adverse health effects, with the potentially unanticipated consequence of targeting developing heart valves.

Transgenic zebrafish reveal tissue-specific differences in estrogen signaling in response to environmental water samples

USGS Publications Warehouse

Gorelick, Daniel A.; Iwanowicz, Luke R.; Hung, Alice L.; Blazer, Vicki; Halpern, Marnie E.

2014-01-01

Background: Environmental endocrine disruptors (EED) are exogenous chemicals that mimic endogenous hormones, such as estrogens. Previous studies using a zebrafish transgenic reporter demonstrated that the EEDs bisphenol A and genistein preferentially activate estrogen receptors (ER) in the larval heart compared to the liver. However, it was not known whether the transgenic zebrafish reporter was sensitive enough to detect estrogens from environmental samples, whether environmental estrogens would exhibit similar tissue-specific effects as BPA and genistein or why some compounds preferentially target receptors in the heart. Methods: We tested surface water samples using a transgenic zebrafish reporter with tandem estrogen response elements driving green fluorescent protein expression (5xERE:GFP). Reporter activation was colocalized with tissue-specific expression of estrogen receptor genes by RNA in situ hybridization. Results: Selective patterns of ER activation were observed in transgenic fish exposed to river water samples from the Mid-Atlantic United States, with several samples preferentially activating receptors in embryonic and larval heart valves. We discovered that tissue-specificity in ER activation is due to differences in the expression of estrogen receptor subtypes. ERα is expressed in developing heart valves but not in the liver, whereas ERβ2 has the opposite profile. Accordingly, subtype-specific ER agonists activate the reporter in either the heart valves or the liver. Conclusion: The use of 5xERE:GFP transgenic zebrafish has revealed an unexpected tissue-specific difference in the response to environmentally relevant estrogenic compounds. Exposure to estrogenic EEDs in utero is associated with adverse health effects, with the potentially unanticipated consequence of targeting developing heart valves.

Melatonin administration alters nicotine preference consumption via signaling through high-affinity melatonin receptors.

PubMed

Horton, William J; Gissel, Hannah J; Saboy, Jennifer E; Wright, Kenneth P; Stitzel, Jerry A

2015-07-01

While it is known that tobacco use varies across the 24-h day, the time-of-day effects are poorly understood. Findings from several previous studies indicate a potential role for melatonin in these time-of-day effects; however, the specific underlying mechanisms have not been well characterized. Understanding of these mechanisms may lead to potential novel smoking cessation treatments. The objective of this study is examine the role of melatonin and melatonin receptors in nicotine free-choice consumption A two-bottle oral nicotine choice paradigm was utilized with melatonin supplementation in melatonin-deficient mice (C57BL/6J) or without melatonin supplementation in mice proficient at melatonin synthesis (C3H/Ibg) compared to melatonin-proficient mice lacking both or one of the high-affinity melatonin receptors (MT1 and MT2; double-null mutant DM, or MT1 or MT2). Preference for bitter and sweet tastants also was assessed in wild-type and MT1 and MT2 DM mice. Finally, home cage locomotor monitoring was performed to determine the effect of melatonin administration on activity patterns. Supplemental melatonin in drinking water significantly reduced free-choice nicotine consumption in C57BL/6J mice, which do not produce endogenous melatonin, while not altering activity patterns. Independently, genetic deletion of both MT1 and MT2 receptors in a melatonin-proficient mouse strain (C3H) resulted in significantly more nicotine consumption than controls. However, single genetic deletion of either the MT1 or MT2 receptor alone did not result in increased nicotine consumption. Deletion of MT1 and MT2 did not impact taste preference. This study demonstrates that nicotine consumption can be affected by exogenous or endogenous melatonin and requires at least one of the high-affinity melatonin receptors. The fact that expression of either the MT1 or MT2 melatonin receptor is sufficient to maintain lower nicotine consumption suggests functional overlap and potential mechanistic explanations.

Automatic method for evaluating the activity of sourdough strains based on gas pressure measurements.

PubMed

Wick, M; Vanhoutte, J J; Adhemard, A; Turini, G; Lebeault, J M

2001-04-01

A new method is proposed for the evaluation of the activity of sourdough strains, based on gas pressure measurements in closed air-tight reactors. Gas pressure and pH were monitored on-line during the cultivation of commercial yeasts and heterofermentative lactic acid bacteria on a semi-synthetic medium with glucose as the major carbon source. Relative gas pressure evolution was compared both to glucose consumption and to acidification and growth. It became obvious that gas pressure evolution is related to glucose consumption kinetics. For each strain, a correlation was made between maximum gas pressure variation and amount of glucose consumed. The mass balance of CO2 in both liquid and gas phase demonstrated that around 90% of CO2 was recovered. Concerning biomass production, a linear relationship was found between log colony-forming units/ml and log pressure for both yeasts and bacteria during the exponential phase; and for yeasts, relative gas pressure evolution also followed optical density variation.

A rapid procedure for the detection and isolation of enterohaemorrhagic Escherichia coli (EHEC) serogroup O26, O103, O111, O118, O121, O145 and O157 strains and the aggregative EHEC O104:H4 strain from ready-to-eat vegetables.

PubMed

Tzschoppe, Markus; Martin, Annett; Beutin, Lothar

2012-01-03

Human infections with Enterohaemorrhagic Escherichia coli strains (EHEC) as agents of Haemorrhagic Colitis (HC) and Haemolytic Uraemic Syndrome (HUS) are frequently associated with the consumption of EHEC contaminated foodstuffs of different origins. EHEC O26, O103, O111, O118, O121, O145 and O157 strains are responsible for the majority of HC and HUS cases worldwide. In May 2011, the emerging aggregative EHEC O104:H4 strain caused a large outbreak with high HUS incidence in northern Germany. Contaminated sprouted seeds were suspected to be the vehicles of transmission. The examination of vegetables retailed for raw consumption revealed low numbers of E. coli (<100 cfu/g) together with high titres of Enterobacteriaceae and Pseudomonas (approx. 5.6 × 10⁷ cfu/g). Specific methods of EHEC detection adapted to vegetables are not yet published. Therefore, we have developed a rapid and sensitive method for detecting low EHEC contamination in vegetables (1-10 cfu/25 g) with artificially EHEC contaminated ready-to-eat salads. A 6-hour enrichment period in BRILA-broth was sufficient to detect 1-10 EHEC from spiked samples after plating 0.1 ml portions of enrichment culture on selective TBX-agar and CHROMagar STEC plates that were incubated at 44 °C overnight. Unlike EHEC strains, the growth of bacteria of the plant flora was substantially inhibited at 44 °C. DNA for real-time PCR detection of EHEC characteristic genes (stx(1), stx(2), eae, ehxA, and O-antigen associated) was prepared with bacteria grown on TBX-agar plates. The storage of EHEC inoculated salad samples for 72 h at 6 °C resulted in a significant reduction (mean value 14.6%) of detectable EHEC, suggesting interference of EHEC with the resident plant microflora. CHROMagar STEC was evaluated as a selective medium for the detection of EHEC strains. Growth on CHROMagar STEC was closely associated with EHEC O26:[H11], O111:[H8], O118:H16, O121:[H19], O145:[H28], O157:[H7] and aggregative EHEC O104:H4 strains and with the presence of the terB gene (tellurite resistance). TerB sequences were found in 87.2% of 235 EHEC but only in only 12.5% of 567 non-EHEC strains. EHEC strains which did not grow on CHROMagar STEC were negative for terB as frequently observed with EHEC O103:H2 (52.9%) and sorbitol-fermenting O157:NM strains (100%). The enrichment and detection method was applied in the examination of sprouted seeds incriminated as vehicles in the EHEC O104:H4 outbreak in Germany. Aggregative EHEC O104:H4 could be detected and isolated from a sample of sprouted seeds which was suspected as vector of transmission of EHEC O104 to humans. Copyright © 2011 Elsevier B.V. All rights reserved.

Staphylococcus aureus adherence to Candida albicans hyphae is mediated by the hyphal adhesin Als3p.

PubMed

Peters, Brian M; Ovchinnikova, Ekaterina S; Krom, Bastiaan P; Schlecht, Lisa Marie; Zhou, Han; Hoyer, Lois L; Busscher, Henk J; van der Mei, Henny C; Jabra-Rizk, Mary Ann; Shirtliff, Mark E

2012-12-01

The bacterium Staphylococcus (St.) aureus and the opportunistic fungus Candida albicans are currently among the leading nosocomial pathogens, often co-infecting critically ill patients, with high morbidity and mortality. Previous investigations have demonstrated preferential adherence of St. aureus to C. albicans hyphae during mixed biofilm growth. In this study, we aimed to characterize the mechanism behind this observed interaction. C. albicans adhesin-deficient mutant strains were screened by microscopy to identify the specific receptor on C. albicans hyphae recognized by St. aureus. Furthermore, an immunoassay was developed to validate and quantify staphylococcal binding to fungal biofilms. The findings from these experiments implicated the C. albicans adhesin agglutinin-like sequence 3 (Als3p) in playing a major role in the adherence process. This association was quantitatively established using atomic force microscopy, in which the adhesion force between single cells of the two species was significantly reduced for a C. albicans mutant strain lacking als3. Confocal microscopy further confirmed these observations, as St. aureus overlaid with a purified recombinant Als3 N-terminal domain fragment (rAls3p) exhibited robust binding. Importantly, a strain of Saccharomyces cerevisiae heterologously expressing Als3p was utilized to further confirm this adhesin as a receptor for St. aureus. Although the parental strain does not bind bacteria, expression of Als3p on the cell surface conferred upon the yeast the ability to strongly bind St. aureus. To elucidate the implications of these in vitro findings in a clinically relevant setting, an ex vivo murine model of co-infection was designed using murine tongue explants. Fluorescent microscopic images revealed extensive hyphal penetration of the epithelium typical of C. albicans mucosal infection. Interestingly, St. aureus bacterial cells were only seen within the epithelial tissue when associated with the invasive hyphae. This differed from tongues infected with St. aureus alone or in conjunction with the als3 mutant strain of C. albicans, where bacterial presence was limited to the outer layers of the oral tissue. Collectively, the findings generated from this study identified a key role for C. albicans Als3p in mediating this clinically relevant fungal-bacterial interaction.

In-vitro and in-vivo evidence of dose-dependent decrease of uropathogenic Escherichia coli virulence after consumption of commercial Vaccinium macrocarpon (cranberry) capsules.

PubMed

Lavigne, J-P; Bourg, G; Combescure, C; Botto, H; Sotto, A

2008-04-01

This study evaluated the antibacterial efficacy of the consumption of cranberry capsules vs. placebo in the urine of healthy volunteers. A first double-blind, randomised, crossover trial involved eight volunteers who had followed three regimens, with or without cranberry, with a wash-out period of at least 6 days between each regimen. Twelve hours after consumption of cranberry or placebo hard capsules, the first urine of the morning was collected. Different Escherichia coli strains were cultured in the urine samples. Urinary antibacterial adhesion activity was measured in vitro using the human T24 epithelial cell-line, and in vivo using the Caenorhabditis elegans killing model. With the in-vitro model, 108 mg of cranberry induced a significant reduction in bacterial adherence to T24 cells as compared with placebo (p <0.001). A significant dose-dependent decrease in bacterial adherence in vitro was noted after the consumption of 108 and 36 mg of cranberry (p <0.001). The in-vivo model confirmed that E. coli strains had a reduced ability to kill C. elegans after growth in the urine of patients who consumed cranberry capsules. Overall, these in-vivo and in-vitro studies suggested that consumption of cranberry juice represents an interesting new strategy to prevent recurrent urinary tract infection.

In-vitro and in-vivo evidence of dose-dependent decrease of uropathogenic Escherichia coli virulence after consumption of commercial Vaccinium macrocarpon (cranberry) capsules

PubMed Central

Lavigne, Jean-Philippe; Bourg, Gisèle; Combescure, Christophe; Botto, Henri; Sotto, Albert

2008-01-01

This study evaluated the antibacterial efficacy of the consumption of cranberry capsules vs. placebo in the urine of healthy volunteers. A first double-blind, randomised, crossover trial involved eight volunteers who had followed three regimens, with or without cranberry, with a wash-out period of at least 6 days between each regimen. Twelve hours after consumption of cranberry or placebo hard capsules, the first urine of the morning was collected. Different Escherichia coli strains were cultured in the urine samples. Urinary antibacterial adhesion activity was measured in vitro using the human T24 epithelial cell-line, and in vivo using the Caenorhabditis elegans killing model. With the in-vitro model, 108 mg of cranberry induced a significant reduction in bacterial adherence to T24 cells as compared with placebo (p <0.001). A significant dose-dependent decrease in bacterial adherence in vitro was noted after the consumption of 108 and 36 mg of cranberry (p <0.001). The in-vivo model confirmed that E. coli strains had a reduced ability to kill C. elegans after growth in the urine of patients who consumed cranberry capsules. Overall, these in-vivo and in-vitro studies suggested that consumption of cranberry juice represents an interesting new strategy to prevent recurrent urinary tract infection. PMID:18190583

Robust Metabolic Responses to Varied Carbon Sources in Natural and Laboratory Strains of Saccharomyces cerevisiae

PubMed Central

Van Voorhies, Wayne A.

2012-01-01

Understanding factors that regulate the metabolism and growth of an organism is of fundamental biologic interest. This study compared the influence of two different carbon substrates, dextrose and galactose, on the metabolic and growth rates of the yeast Saccharomyces cerevisiae. Yeast metabolic and growth rates varied widely depending on the metabolic substrate supplied. The metabolic and growth rates of a yeast strain maintained under long-term laboratory conditions was compared to strain isolated from natural condition when grown on different substrates. Previous studies had determined that there are numerous genetic differences between these two strains. However, the overall metabolic and growth rates of a wild isolate of yeast was very similar to that of a strain that had been maintained under laboratory conditions for many decades. This indicates that, at in least this case, metabolism and growth appear to be well buffered against genetic differences. Metabolic rate and cell number did not co-vary in a simple linear manner. When grown in either dextrose or galactose, both strains showed a growth pattern in which the number of cells continued to increase well after the metabolic rate began a sharp decline. Previous studied have reported that O2 consumption in S. cerevisiae grown in reduced dextrose levels were elevated compared to higher levels. Low dextrose levels have been proposed to induce caloric restriction and increase life span in yeast. However, there was no evidence that reduced levels of dextrose increased metabolic rates, measured by either O2 consumption or CO2 production, in the strains used in this study. PMID:22253874

Iron Corrosion Induced by Nonhydrogenotrophic Nitrate-Reducing Prolixibacter sp. Strain MIC1-1

PubMed Central

Ito, Kimio; Wakai, Satoshi; Tsurumaru, Hirohito; Ohkuma, Moriya; Harayama, Shigeaki

2014-01-01

Microbiologically influenced corrosion (MIC) of metallic materials imposes a heavy economic burden. The mechanism of MIC of metallic iron (Fe0) under anaerobic conditions is usually explained as the consumption of cathodic hydrogen by hydrogenotrophic microorganisms that accelerates anodic Fe0 oxidation. In this study, we describe Fe0 corrosion induced by a nonhydrogenotrophic nitrate-reducing bacterium called MIC1-1, which was isolated from a crude-oil sample collected at an oil well in Akita, Japan. This strain requires specific electron donor-acceptor combinations and an organic carbon source to grow. For example, the strain grew anaerobically on nitrate as a sole electron acceptor with pyruvate as a carbon source and Fe0 as the sole electron donor. In addition, ferrous ion and l-cysteine served as electron donors, whereas molecular hydrogen did not. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain MIC1-1 was a member of the genus Prolixibacter in the order Bacteroidales. Thus, Prolixibacter sp. strain MIC1-1 is the first Fe0-corroding representative belonging to the phylum Bacteroidetes. Under anaerobic conditions, Prolixibacter sp. MIC1-1 corroded Fe0 concomitantly with nitrate reduction, and the amount of iron dissolved by the strain was six times higher than that in an aseptic control. Scanning electron microscopy analyses revealed that microscopic crystals of FePO4 developed on the surface of the Fe0 foils, and a layer of FeCO3 covered the FePO4 crystals. We propose that cells of Prolixibacter sp. MIC1-1 accept electrons directly from Fe0 to reduce nitrate. PMID:25548048

Detection and Phylogenetic Characterization of Human Hepatitis E Virus Strains, Czech Republic

PubMed Central

Slany, Michal; Chalupa, Pavel; Holub, Michal; Svoboda, Radek; Pavlik, Ivo

2011-01-01

To determine the origin of hepatitis E virus in the Czech Republic, we analyzed patient clinical samples. Five isolates of genotypes 3e, 3f, and 3g were obtained. Their genetic relatedness with Czech strains from domestic pigs and wild boars and patient recollections suggest an autochthonous source likely linked to consumption of contaminated pork. PMID:21529412

The influence of age on perceptions of anticipated financial inadequacy by palliative radiation outpatients.

PubMed

Francoeur, Richard B

2007-12-01

A consistent body of knowledge suggests that with advancing age, adults tend to report lower financial strain from their current economic condition. But are more negative perceptions shifted onto their expectations about their future economic condition? This study of seriously ill outpatients investigates whether advancing age is related to more negative expectations of future health-related financial strain, in which illness progression would necessitate greater health care consumption. Ordinal probit multivariate regression was conducted on survey findings from 268 outpatients initiating palliative radiation for recurrent cancer. Half were retirees age>/=65. Age comparisons are reported when there was no recent work transition. As age advances (from 40 to 84), outpatients incurring low objective financial stress were more likely to reveal that their health insurance and finances would be less adequate to meet future health needs. Previously, these outpatients were reported to minimize perceptions of current financial strain as age advances. Therefore, older outpatients may cope with current circumstances by displacing perceptions of financial inadequacy onto plausible future situations of cancer progression demanding greater healthcare consumption. Financial strain may be hidden in older outpatients initiating palliative radiation. These outpatients appear at risk of foregoing appropriate healthcare. Targeted screening and advocacy are warranted.

Which key properties controls the preferential transport in the vadose zone under transient hydrological conditions

NASA Astrophysics Data System (ADS)

Groh, J.; Vanderborght, J.; Puetz, T.; Gerke, H. H.; Rupp, H.; Wollschlaeger, U.; Stumpp, C.; Priesack, E.; Vereecken, H.

2015-12-01

Understanding water flow and solute transport in the unsaturated zone is of great importance for an appropriate land use management strategy. The quantification and prediction of water and solute fluxes through the vadose zone can help to improve management practices in order to limit potential risk on our fresh water resources. Water related solute transport and residence time is strongly affected by preferential flow paths in the soil. Water flow in soils depends on soil properties and site factors (climate or experiment conditions, land use) and are therefore important factors to understand preferential solute transport in the unsaturated zone. However our understanding and knowledge of which on-site properties or conditions define and enhance preferential flow and transport is still poor and mostly limited onto laboratory experimental conditions (small column length and steady state boundary conditions). Within the TERENO SOILCan lysimeter network, which was designed to study the effects of climate change on soil functions, a bromide tracer was applied on 62 lysimeter at eight different test sites between Dec. 2013 and Jan. 2014. The TERENO SOILCan infrastructure offers the unique possibility to study the occurrence of preferential flow and transport of various soil types under different natural transient hydrological conditions and land use (crop, bare and grassland) at eight TERENO SOILCan observatories. Working with lysimeter replicates at each observatory allows defining the spatial variability of preferential transport and flow. Additionally lysimeters in the network were transferred within and between observatories in order to subject them to different rainfall and temperature regimes and enable us to relate the soil type susceptibility of preferential flow and transport not only to site specific physical and land use properties, but also to different transient boundary conditions. Comparison and statistical analysis between preferential flow indicators 5% arrival time and potential key soil properties, site factors and boundary conditions will be presented in order to identify key properties which control the preferential transport in the vadose zone under transient hydrological conditions.

Generation and selection of anti-flagellin monoclonal antibodies useful for serotyping Salmonella enterica.

PubMed

Hiriart, Yanina; Serradell, Maria; Martínez, Araci; Sampaolesi, Sofia; Maciel, Dolores Gonzalez; Chabalgoity, Jose Alejandro; Yim, Lucía; Algorta, Gabriela; Rumbo, Martin

2013-01-01

In developing countries, bacterial acute gastroenteritis continues to be an important cause of morbidity and mortality among young children. Salmonellosis constitutes a major cause of infectious enteritis worldwide, most of them associated to the consumption of contaminated food products. Traditionally, Salmonella has been classified in serovars based on varieties of O and H surface antigens. In the present work we generated and characterized a panel of anti-flagellin monoclonal antibodies (MAbs) in order to select antibodies useful for detecting the H surface antigen. Four different MAbs were obtained by somatic hybridization of splenocytes. We found two MAbs that recognised regions of flagellin conserved among different Salmonella serovars. Other two MAbs recognised structures restricted to Salmonella enterica sv. Typhimurium, being one of them suitable for agglutination tests. Using a diverse panel of S. enterica serovars with different H antigen varieties we confirmed that this MAb agglutinates specifically S. Typhimurium (antigenic formula: 4,12:i:1,2) or other serovars expressing flagellar factor i. In conclusion, we generated a valuable immunochemical tool to be used in simple assays for serotyping of epidemiologically relevant strains. The capacity to characterize specific strains and determine the primary sources of Salmonella contamination generate valuable information of the epidemiology of this microorganism, contributing to the improvement of public health.

Diversity and distribution of cholix toxin, a novel ADP-ribosylating factor from Vibrio cholerae.

PubMed

Purdy, Alexandra E; Balch, Deborah; Lizárraga-Partida, Marcial Leonardo; Islam, Mohammad Sirajul; Martinez-Urtaza, Jaime; Huq, Anwar; Colwell, Rita R; Bartlett, Douglas H

2010-02-01

Non-toxigenic non-O1, non-O139 Vibrio cholerae strains isolated from both environmental and clinical settings carry a suite of virulence factors aside from cholera toxin. Among V. cholerae strains isolated from coastal waters of southern California, this includes cholix toxin, an ADP-ribosylating factor that is capable of halting protein synthesis in eukaryotic cells. The prevalence of the gene encoding cholix toxin, chxA, was assessed among a collection of 155 diverse V. cholerae strains originating from both clinical and environmental settings in Bangladesh and Mexico and other countries around the globe. The chxA gene was present in 47% of 83 non-O1, non-O139 strains and 16% of 72 O1/O139 strains screened as part of this study. A total of 86 chxA gene sequences were obtained, and phylogenetic analysis revealed that they fall into two distinct clades. These two clades were also observed in the phylogenies of several housekeeping genes, suggesting that the divergence observed in chxA extends to other regions of the V. cholerae genome, and most likely has arisen from vertical descent rather than horizontal transfer. Our results clearly indicate that ChxA is a major toxin of V. cholerae with a worldwide distribution that is preferentially associated with non-pandemic strains. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd.

Characteristics of strain-sensitive photonic crystal cavities in a flexible substrate.

PubMed

No, You-Shin; Choi, Jae-Hyuck; Kim, Kyoung-Ho; Park, Hong-Gyu

2016-11-14

High-index semiconductor photonic crystal (PhC) cavities in a flexible substrate support strong and tunable optical resonances that can be used for highly sensitive and spatially localized detection of mechanical deformations in physical systems. Here, we report theoretical studies and fundamental understandings of resonant behavior of an optical mode excited in strain-sensitive rod-type PhC cavities consisting of high-index dielectric nanorods embedded in a low-index flexible polymer substrate. Using the three-dimensional finite-difference time-domain simulation method, we calculated two-dimensional transverse-electric-like photonic band diagrams and the three-dimensional dispersion surfaces near the first Γ-point band edge of unidirectionally strained PhCs. A broken rotational symmetry in the PhCs modifies the photonic band structures and results in the asymmetric distributions and different levels of changes in normalized frequencies near the first Γ-point band edge in the reciprocal space, which consequently reveals strain-dependent directional optical losses and selected emission patterns. The calculated electric fields, resonant wavelengths, and quality factors of the band-edge modes in the strained PhCs show an excellent agreement with the results of qualitative analysis of modified dispersion surfaces. Furthermore, polarization-resolved time-averaged Poynting vectors exhibit characteristic dipole-like emission patterns with preferentially selected linear polarizations, originating from the asymmetric band structures in the strained PhCs.

Structure of Laminar Permanently Blue, Opposed-Jet Ethylene-Fueled Diffusion Flames

NASA Technical Reports Server (NTRS)

Lin, K.-C.; Faeth, G. M.; Urban, D. L. (Technical Monitor)

2000-01-01

The structure and state relationships of laminar soot-free (permanently blue) ethylene-fueled diffusion flames at various strain rates were studied both experimentally and computationally using an opposed-jet configuration. Measurements of gas velocities, temperatures, and compositions were carried out along the stagnation stream line. Corresponding predictions of flame structure were obtained, based on numerical simulations using several contemporary reaction mechanisms for methane oxidation. Flame conditions studied included ethylene-fueled opposed-jet diffusion flames having stoichiometric mixture fractions of 0.7 with measurements involving strain rates of 60-240/s and predictions involving strain rates of 0-1140/s at normal temperature and pressure. It was found that measured major gas species concentrations and temperature distributions were in reasonably good agreement with predictions using mechanisms due to GRI-Mech and Peters and that effects of preferential diffusion significantly influence flame structure even when reactant mass diffusivities are similar. Oxygen leakage to fuel-rich conditions and carbon monoxide leakage to fuel-lean conditions both increased as strain rates increased. Furthermore, increased strain rates caused increased fuel concentrations near the flame sheet, decreased peak gas temperatures, and decreased concentrations of carbon dioxide and water vapor throughout the flames. State relationships for major gas species and gas temperatures were found to exist over a broad range of strain rates, providing potential for significant computational simplifications for modeling purposes in some instances.

Structure of Laminar Permanently Blue, Opposed-Jet Ethylene-Fueled Diffusion Flames. Appendix E

NASA Technical Reports Server (NTRS)

Lin, K.-C.; Faeth, G. M.; Urban, D. L. (Technical Monitor)

2000-01-01

The structure and state relationships of laminar soot-free (permanently blue) ethylene-fueled diffusion flames at various strain rates were studied both experimentally and computationally using an opposed-jet configuration. Measurements of gas velocities, temperatures, and compositions were carried out along the stagnation stream line. Corresponding predictions of flame structure were obtained, based on numerical simulations using several contemporary reaction mechanisms for methane oxidation. Flame conditions studied included ethylene-fueled opposed-jet diffusion flames having stoichiometric mixture fractions of 0.7 with measurements involving strain rates of 60-240/s and predictions involving strain rates of 0-1140/s at normal temperature and pressure. It was found that measured major gas species concentrations and temperature distributions were in reasonably good agreement with predictions using mechanisms due to GRI-Mech and Peters and that effects of preferential diffusion significantly influence flame structure even when reactant mass diffusivities are similar. Oxygen leakage to fuel-rich conditions and carbon monoxide leakage to fuel-lean conditions both increased as strain rates increased. Furthermore, increased strain rates caused increased fuel concentrations near the flame sheet, decreased peak gas temperatures, and decreased concentrations of carbon dioxide and water vapor throughout the flames. State relationships for major gas species and gas temperatures were found to exist over a broad range of strain rates, providing potential for significant computational simplifications for modeling purposes in some instances.

Molecular characterizations of Vibrio parahaemolyticus in seafood from the Black Sea, Turkey.

PubMed

Terzi Gulel, G; Martinez-Urtaza, J

2016-06-01

Vibrio parahaemolyticus is a marine bacterium that is considered as one of the major causes of bacterial food-borne outbreaks at a global scale. A total of 114 samples including mussel (n = 42), seawater (n = 22) and fish (n = 50) samples were collected and subjected to investigation. Vibrio parahaemolyticus was detected in 45 (39%) of 114 samples with an occurrence in mussel, seawater and fish samples of 76, 40·9 and 8% respectively. A total of 96 isolates were positive for the species-specific genes toxR and tlh and confirmed as V. parahaemolyticus. Presence of the virulence marker gene tdh was not identified in any of the strains investigated; however, four of strains were positive for the trh gene. Serological analysis of eight randomly selected trh-negative isolates identified three different serotypes: O4:K untypeable (KUT), O2:KUT, O3:KUT. Conversely, all four trh-positive strains belonged to a single serotype (O1:K1) and share an undistinguishable genetic profile by PFGE analysis, suggesting the existence of a dominant clone for the trh-positive strains in the region. Vibrio parahaemolyticus is the most prevalent food-poisoning bacterium associated with seafood consumption. The number of infections is increasing worldwide and is being reported in areas with no previous incidence. This study provides the first instance of the occurrence of V. parahaemolyticus strains with virulence traits in the Black Sea, contributing to gain a better understanding about potential risk associated with this pathogen in the region. © 2016 The Society for Applied Microbiology.

Ultralow-power electronics for biomedical applications.

PubMed

Chandrakasan, Anantha P; Verma, Naveen; Daly, Denis C

2008-01-01

The electronics of a general biomedical device consist of energy delivery, analog-to-digital conversion, signal processing, and communication subsystems. Each of these blocks must be designed for minimum energy consumption. Specific design techniques, such as aggressive voltage scaling, dynamic power-performance management, and energy-efficient signaling, must be employed to adhere to the stringent energy constraint. The constraint itself is set by the energy source, so energy harvesting holds tremendous promise toward enabling sophisticated systems without straining user lifestyle. Further, once harvested, efficient delivery of the low-energy levels, as well as robust operation in the aggressive low-power modes, requires careful understanding and treatment of the specific design limitations that dominate this realm. We outline the performance and power constraints of biomedical devices, and present circuit techniques to achieve complete systems operating down to power levels of microwatts. In all cases, approaches that leverage advanced technology trends are emphasized.

Impact of genetic strain on body fat loss, food consumption, metabolism, ventilation, and motor activity in free running female rats.

PubMed

Gordon, C J; Phillips, P M; Johnstone, A F M

2016-01-01

Chronic exercise is considered as one of the most effective means of countering symptoms of the metabolic syndrome (MS) such as obesity and hyperglycemia. Rodent models of forced or voluntary exercise are often used to study the mechanisms of MS and type 2 diabetes. However, there is little known on the impact of genetic strain on the metabolic response to exercise. We studied the effects of housing rats with running wheels (RW) for 65 days compared to sedentary (SED) housing in five female rat strains: Sprague-Dawley (SD), Long-Evans (LE), Wistar (WIS), spontaneously hypertensive (SHR), and Wistar-Kyoto (WKY). Key parameters measured were total distance run, body composition, food consumption, motor activity, ventilatory responses by plethysmography, and resting metabolic rate (MR). WKY and SHR ran significantly more than the WIS, LE, and SD strains. Running-induced reduction in body fat was affected by strain but not by distance run. LE's lost 6% fat after 21 d of running whereas WKY's lost 2% fat but ran 40% more than LE's. LE and WIS lost body weight while the SHR and WKY strains gained weight during running. Food intake with RW was markedly increased in SHR, WIS, and WKY while LE and SD showed modest increases. Exploratory motor activity was reduced sharply by RW in all but the SD strain. Ventilatory parameters were primarily altered by RW in the SHR, WKY, and WIS strains. MR was unaffected by RW. In an overall ranking of physiological and behavioral responses to RW, the SD strain was considered the least responsive whereas the WIS was scored as most responsive. In terms of RW-induced fat loss, the LE strain appears to be the most ideal. These results should be useful in the future selection of rat models to study benefits of volitional exercise. Published by Elsevier Inc.

Transcriptional Modulation of Transport- and Metabolism-Associated Gene Clusters Leading to Utilization of Benzoate in Preference to Glucose in Pseudomonas putida CSV86

PubMed Central

Choudhary, Alpa; Modak, Arnab; Apte, Shree K.

2017-01-01

ABSTRACT The effective elimination of xenobiotic pollutants from the environment can be achieved by efficient degradation by microorganisms even in the presence of sugars or organic acids. Soil isolate Pseudomonas putida CSV86 displays a unique ability to utilize aromatic compounds prior to glucose. The draft genome and transcription analyses revealed that glucose uptake and benzoate transport and metabolism genes are clustered at the glc and ben loci, respectively, as two distinct operons. When grown on glucose plus benzoate, CSV86 displayed significantly higher expression of the ben locus in the first log phase and of the glc locus in the second log phase. Kinetics of substrate uptake and metabolism matched the transcription profiles. The inability of succinate to suppress benzoate transport and metabolism resulted in coutilization of succinate and benzoate. When challenged with succinate or benzoate, glucose-grown cells showed rapid reduction in glc locus transcription, glucose transport, and metabolic activity, with succinate being more effective at the functional level. Benzoate and succinate failed to interact with or inhibit the activities of glucose transport components or metabolic enzymes. The data suggest that succinate and benzoate suppress glucose transport and metabolism at the transcription level, enabling P. putida CSV86 to preferentially metabolize benzoate. This strain thus has the potential to be an ideal host to engineer diverse metabolic pathways for efficient bioremediation. IMPORTANCE Pseudomonas strains play an important role in carbon cycling in the environment and display a hierarchy in carbon utilization: organic acids first, followed by glucose, and aromatic substrates last. This limits their exploitation for bioremediation. This study demonstrates the substrate-dependent modulation of ben and glc operons in Pseudomonas putida CSV86, wherein benzoate suppresses glucose transport and metabolism at the transcription level, leading to preferential utilization of benzoate over glucose. Interestingly, succinate and benzoate are cometabolized. These properties are unique to this strain compared to other pseudomonads and open up avenues to unravel novel regulatory processes. Strain CSV86 can serve as an ideal host to engineer and facilitate efficient removal of recalcitrant pollutants even in the presence of simpler carbon sources. PMID:28733285

Biochemical, genetic, and epidemiologic characterization of Haemophilus influenzae biogroup aegyptius (Haemophilus aegyptius) strains associated with Brazilian purpuric fever.

PubMed Central

Brenner, D J; Mayer, L W; Carlone, G M; Harrison, L H; Bibb, W F; Brandileone, M C; Sottnek, F O; Irino, K; Reeves, M W; Swenson, J M

1988-01-01

Brazilian purpuric fever (BPF) is a recently recognized fulminant pediatric disease characterized by fever, with rapid progression to purpura, hypotensive shock, and death. BPF is usually preceded by purulent conjunctivitis that has resolved before the onset of fever. Both the conjunctivitis and BPF are caused by Haemophilus influenzae biogroup aegyptius (formerly called H. aegyptius). Isolates from 15 BPF cases, mainly from blood or hemorrhagic cerebrospinal fluid, case-associated isolates from 42 persons in towns where BPF cases occurred, and control strains from 32 persons in towns without BPF cases were characterized biochemically, genetically, and epidemiologically. Results indicated that a single clone was responsible for all BPF cases identified in six Brazilian towns from 1984 through 1986. All of 15 (100%) case strains were the same clone as was 1 of 32 (3%) control strains (P = less than 10(-8). Isolates of the clone were preferentially intrarelated by DNA hybridization (99% relatedness, hydroxyapatite method at 60 and 75 degrees C) and were separable from other H. influenzae biogroup aegyptius strains (approximately 90% relatedness at 60 degrees C and 82% relatedness at 75 degrees C). All isolates of the BPF clone and no other strains contained a 24-megadalton plasmid of restriction endonuclease type 3031, were of a single multilocus enzyme mobility type, were of a single sodium dodecyl sulfate-polyacrylamide gel electrophoresis type, and were in one of two ribosomal DNA restriction patterns. All BPF clone isolates reacted with monoclonal antibodies produced from a case strain; only 3 of 62 (5%) other strains reacted with this monoclonal antibody. Ninety percent of BPF clone strains and 27% of other strains were relatively resistant to sulfamethoxazole-trimethoprim. Images PMID:3262623

Chlorella for protein and biofuels: from strain selection to outdoor cultivation in a Green Wall Panel photobioreactor

PubMed Central

2014-01-01

Background Chlorella is one of the few microalgae employed for human consumption. It typically has a high protein content, but it can also accumulate high amounts of lipids or carbohydrates under stress conditions and, for this reason, it is of interest in the production of biofuels. High production costs and energy consumption are associated with its cultivation. This work describes a strategy to reduce costs and environmental impact of Chlorella biomass production for food, biofuels and other applications. Results The growth of four Chlorella strains, selected after a laboratory screening, was investigated outdoors in a low-cost 0.25 m2 GWP-II photobioreactor. The capacity of the selected strains to grow at high temperature was tested. On the basis of these results, in the nitrogen starvation trials the culture was cooled only when the temperature exceeded 40°C to allow for significant energy savings, and performed in a seawater-based medium to reduce the freshwater footprint. Under nutrient sufficiency, strain CH2 was the most productive. In all the strains, nitrogen starvation strongly reduced productivity, depressed protein and induced accumulation of carbohydrate (about 50%) in strains F&M-M49 and IAM C-212, and lipid (40 - 45%) in strains PROD1 and CH2. Starved cultures achieved high storage product productivities: 0.12 g L−1 d−1 of lipids for CH2 and 0.19 g L−1 d−1 of carbohydrates for F&M-M49. When extrapolated to large-scale in central Italy, CH2 showed a potential productivity of 41 t ha−1 y−1 for biomass, 16 t ha−1 y−1 for protein and 11 t ha−1 y−1 for lipid under nutrient sufficiency, and 8 t ha−1 y−1 for lipid under nitrogen starvation. Conclusions The environmental and economic sustainability of Chlorella production was enhanced by growing the organisms in a seawater-based medium, so as not to compete with crops for freshwater, and at high temperatures, so as to reduce energy consumption for cooling. All the four selected strains are good candidates for food or biofuels production in lands unsuitable for conventional agriculture. Chlorella strain CH2 has the potential for more than 80 tonnes of biomass, 32 tonnes of protein and 22 tonnes of lipid per year under favourable climates. PMID:24932216

Differential Potassium Channel Gene Regulation in BXD Mice Reveals Novel Targets for Pharmacogenetic Therapies to Reduce Heavy Alcohol Drinking

PubMed Central

Rinker, Jennifer A.; Fulmer, Diana B.; Trantham-Davidson, Heather; Smith, Maren L.; Williams, Robert W.; Lopez, Marcelo F.; Randall, Patrick K.; Chandler, L. Judson; Miles, Michael F.; Becker, Howard C.; Mulholland, Patrick J.

2016-01-01

Alcohol (ethanol) dependence is a chronic relapsing brain disorder partially influenced by genetics and characterized by an inability to regulate harmful levels of drinking. Emerging evidence has linked genes that encode KV7, KIR, and KCa2 K+ channels with variation in alcohol-related behaviors in rodents and humans. This led us to experimentally test relations between K+ channel genes and escalation of drinking in a chronic intermittent ethanol (CIE) exposure model of dependence in BXD recombinant inbred strains of mice. Transcript levels for K+ channel genes in the prefrontal cortex (PFC) and nucleus accumbens (NAc) covary with voluntary ethanol drinking in a non-dependent cohort. Transcripts that encode KV7 channels covary negatively with drinking in non-dependent BXD strains. Using a pharmacological approach to validate the genetic findings, C57BL/6J mice were allowed intermittent access to ethanol to establish baseline consumption before they were treated with retigabine, an FDA-approved KV7 channel positive modulator. Systemic administration significantly reduced drinking, and consistent with previous evidence, retigabine was more effective at reducing voluntary consumption in high-drinking than low-drinking subjects. We evaluated the specific K+ channel genes that were most sensitive to CIE exposure and identified a gene subset in the NAc and PFC dysregulated in the alcohol-dependent BXD cohort. CIE-induced modulation of nine genes in the NAc and six genes in the PFC covaried well with the changes in drinking induced by ethanol dependence. Here we identified novel candidate genes in the NAc and PFC that are regulated by ethanol dependence and correlate with voluntary drinking in non-dependent and dependent BXD mice. The findings that Kcnq expression correlate with drinking and that retigabine reduces consumption suggest that KV7 channels could be pharmacogenetic targets to treat individuals with alcohol addiction. PMID:27432260

Characterization and Evolution of Anthranilate 1,2-Dioxygenase from Acinetobacter sp. Strain ADP1

PubMed Central

Eby, D. Matthew; Beharry, Zanna M.; Coulter, Eric D.; Kurtz, Donald M.; Neidle, Ellen L.

2001-01-01

The two-component anthranilate 1,2-dioxygenase of the bacterium Acinetobacter sp. strain ADP1 was expressed in Escherichia coli and purified to homogeneity. This enzyme converts anthranilate (2-aminobenzoate) to catechol with insertion of both atoms of O2 and consumption of one NADH. The terminal oxygenase component formed an α3β3 hexamer of 54- and 19-kDa subunits. Biochemical analyses demonstrated one Rieske-type [2Fe-2S] center and one mononuclear nonheme iron center in each large oxygenase subunit. The reductase component, which transfers electrons from NADH to the oxygenase component, was found to contain approximately one flavin adenine dinucleotide and one ferredoxin-type [2Fe-2S] center per 39-kDa monomer. Activities of the combined components were measured as rates and quantities of NADH oxidation, substrate disappearance, product appearance, and O2 consumption. Anthranilate conversion to catechol was stoichiometrically coupled to NADH oxidation and O2 consumption. The substrate analog benzoate was converted to a nonaromatic benzoate 1,2-diol with similarly tight coupling. This latter activity is identical to that of the related benzoate 1,2-dioxygenase. A variant anthranilate 1,2-dioxygenase, previously found to convey temperature sensitivity in vivo because of a methionine-to-lysine change in the large oxygenase subunit, was purified and characterized. The purified M43K variant, however, did not hydroxylate anthranilate or benzoate at either the permissive (23°C) or nonpermissive (39°C) growth temperatures. The wild-type anthranilate 1,2-dioxygenase did not efficiently hydroxylate methylated or halogenated benzoates, despite its sequence similarity to broad-substrate specific dioxygenases that do. Phylogenetic trees of the α and β subunits of these terminal dioxygenases that act on natural and xenobiotic substrates indicated that the subunits of each terminal oxygenase evolved from a common ancestral two-subunit component. PMID:11114907

Region-specific chromatin decondensation and micronucleus formation induced by 5-azacytidine in human TIG-7 cells.

PubMed

Satoh, T; Yamamoto, K; Miura, K F; Sofuni, T

2004-01-01

A human diploid lung fibroblast cell strain, TIG-7, has a heteromorphic chromosome 15 with an extra short arm carrying a homogeneously staining region (15p+hsr). We demonstrated previously that the 15p+hsr consists of an inactive and G+C-rich rDNA cluster characterized by fluorescence in situ hybridization (FISH) and various chromosome banding techniques. Thus, it was suggested that the region could contain highly methylated DNA. To observe methylation status on the target region directly under the microscope, we used a demethylating agent, 5-azacytidine (5-azaC), to induce decondensation of the chromatin containing methylated DNA. At 24 h after treatment with 0.5 microM 5-azaC, marked decondensation of the 15p+hsr was observed in almost all of the metaphases. Furthermore, we observed micronuclei, which were equivalent to the rDNA of the 15p+hsr demonstrated by FISH in the same preparation. In contrast, the DNA cross-linking agent mitomycin C (MMC) preferentially induced 15p+hsr-negative micronuclei. These findings indicated that chromatin decondensation and subsequent DNA strand breakage induced by the demethylating effect of 5-azaC led specifically to 15p+hsr-positive micronuclei. Copyright 2003 S. Karger AG, Basel

Impact of heat release on strain rate field in turbulent premixed Bunsen flames

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coriton, Bruno Rene Leon; Frank, Jonathan H.

2016-08-10

The effects of combustion on the strain rate field are investigated in turbulent premixed CH 4/air Bunsen flames using simultaneous tomographic PIV and OH LIF measurements. Tomographic PIV provides three-dimensional velocity measurements, from which the complete strain rate tensor is determined. The OH LIF measurements are used to determine the position of the flame surface and the flame-normal orientation within the imaging plane. This combination of diagnostic techniques enables quantification of divergence as well as flame-normal and tangential strain rates, which are otherwise biased using only planar measurements. Measurements are compared in three lean-to-stoichiometric flames that have different amounts ofmore » heat release and Damköhler numbers greater than unity. The effects of heat release on the principal strain rates and their alignment relative to the local flame normal are analyzed. The extensive strain rate preferentially aligns with the flame normal in the reaction zone, which has been indicated by previous studies. The strength of this alignment increases with increasing heat release and, as a result, the flame-normal strain rate becomes highly extensive. These effects are associated with the gas expansion normal to the flame surface, which is largest for the stoichiometric flame. In the preheat zone, the compressive strain rate has a tendency to align with the flame normal. Away from the flame front, the flame – strain rate alignment is arbitrary in both the reactants and products. The flame-tangential strain rate is on average positive across the flame front, and therefore the turbulent strain rate field contributes to the enhancement of scalar gradients as in passive scalar turbulence. As a result, increases in heat release result in larger positive values of the divergence as well as flame-normal and tangential strain rates, the tangential strain rate has a weaker dependence on heat release than the flame-normal strain rate and the divergence.« less

The Contribution of Experimental in vivo Models to Understanding the Mechanisms of Adaptation to Mechanical Loading in Bone

PubMed Central

Meakin, Lee B.; Price, Joanna S.; Lanyon, Lance E.

2014-01-01

Changing loading regimens by natural means such as exercise, with or without interference such as osteotomy, has provided useful information on the structure:function relationship in bone tissue. However, the greatest precision in defining those aspects of the overall strain environment that influence modeling and remodeling behavior has been achieved by relating quantified changes in bone architecture to quantified changes in bones’ strain environment produced by direct, controlled artificial bone loading. Jiri Hert introduced the technique of artificial loading of bones in vivo with external devices in the 1960s using an electromechanical device to load rabbit tibiae through transfixing stainless steel pins. Quantifying natural bone strains during locomotion by attaching electrical resistance strain gages to bone surfaces was introduced by Lanyon, also in the 1960s. These studies in a variety of bones in a number of species demonstrated remarkable uniformity in the peak strains and maximum strain rates experienced. Experiments combining strain gage instrumentation with artificial loading in sheep, pigs, roosters, turkeys, rats, and mice has yielded significant insight into the control of strain-related adaptive (re)modeling. This diversity of approach has been largely superseded by non-invasive transcutaneous loading in rats and mice, which is now the model of choice for many studies. Together such studies have demonstrated that over the physiological strain range, bone’s mechanically adaptive processes are responsive to dynamic but not static strains; the size and nature of the adaptive response controlling bone mass is linearly related to the peak loads encountered; the strain-related response is preferentially sensitive to high strain rates and unresponsive to static ones; is most responsive to unusual strain distributions; is maximized by remarkably few strain cycles, and that these are most effective when interrupted by short periods of rest between them. PMID:25324829

Effect of precursor solutions on ZnO film via solution precursor plasma spray and corresponding gas sensing performances

NASA Astrophysics Data System (ADS)

Yu, Z. X.; Ma, Y. Z.; Zhao, Y. L.; Huang, J. B.; Wang, W. Z.; Moliere, M.; Liao, H. L.

2017-08-01

Solution precursor plasma spraying (SPPS) as a novel thermal spray method was employed to deposit nano-structured ZnO thin film using different formulations of the precursor solution. This article focuses on the influence of the solution composition on the preferential orientation of crystal growth, on crystal size and surface morphology of the resulting ZnO films. The trend of preferential growth along (002) lattice plane of ZnO film was studied by slow scanning X-ray diffraction using a specific coefficient P(002). It appears that the thermal spray process promotes the buildup of ZnO films preferentially oriented along the c-axis. The shape of single particle tends to change from round shaped beads to hexagonal plates by increasing the volume ratio of ethanol in the solvent. Both cauliflower and honeycomb-like surface morphologies featuring high specific surface area and roughness were obtained through the SPPS process by varying solution composition. These ZnO films are hydrophobic with contact angle as high as 136°, which is seemingly associated with micro reliefs developing high surface specific area. Then the gas sensing performances of ZnO films preferentially oriented along (002) face were tentatively predicted using the "first principle calculation method" and were compared with those of conventional films that are mainly oriented along the (101) face. The (002) face displays better hydrogen adsorption capability than the (101) face with much larger resulting changes in electrical resistance. In conclusion, the c-axis oriented ZnO films obtained through SSPS have favorable performances to be used as sensitive layer in gas sensing applications.

Different categories of living and non-living sound-sources activate distinct cortical networks

PubMed Central

Engel, Lauren R.; Frum, Chris; Puce, Aina; Walker, Nathan A.; Lewis, James W.

2009-01-01

With regard to hearing perception, it remains unclear as to whether, or the extent to which, different conceptual categories of real-world sounds and related categorical knowledge are differentially represented in the brain. Semantic knowledge representations are reported to include the major divisions of living versus non-living things, plus more specific categories including animals, tools, biological motion, faces, and places—categories typically defined by their characteristic visual features. Here, we used functional magnetic resonance imaging (fMRI) to identify brain regions showing preferential activity to four categories of action sounds, which included non-vocal human and animal actions (living), plus mechanical and environmental sound-producing actions (non-living). The results showed a striking antero-posterior division in cortical representations for sounds produced by living versus non-living sources. Additionally, there were several significant differences by category, depending on whether the task was category-specific (e.g. human or not) versus non-specific (detect end-of-sound). In general, (1) human-produced sounds yielded robust activation in the bilateral posterior superior temporal sulci independent of task. Task demands modulated activation of left-lateralized fronto-parietal regions, bilateral insular cortices, and subcortical regions previously implicated in observation-execution matching, consistent with “embodied” and mirror-neuron network representations subserving recognition. (2) Animal action sounds preferentially activated the bilateral posterior insulae. (3) Mechanical sounds activated the anterior superior temporal gyri and parahippocampal cortices. (4) Environmental sounds preferentially activated dorsal occipital and medial parietal cortices. Overall, this multi-level dissociation of networks for preferentially representing distinct sound-source categories provides novel support for grounded cognition models that may underlie organizational principles for hearing perception. PMID:19465134

Strain-specific reverse transcriptase PCR assay: means to distinguish candidate vaccine from wild-type strains of respiratory syncytial virus.

PubMed Central

Zheng, H; Peret, T C; Randolph, V B; Crowley, J C; Anderson, L J

1996-01-01

Candidate live-virus vaccines for respiratory syncytial virus are being developed and are beginning to be evaluated in clinical trials. To distinguish candidate vaccine strains from wild-type strains isolated during these trials, we developed PCR assays specific to two sets of candidate vaccine strains. The two sets were a group A strain (3A), its three attenuated, temperature-sensitive variant strains, a group B strain (2B), and its four attenuated, temperature-sensitive variant strains. The PCR assays were evaluated by testing 18 group A wild-type strains, the 3A strains, 9 group B wild-type strains, and the 2B strains. PCR specific to group A wild-type strains amplified only group A wild-type strains, and 3A-specific PCR amplified only 3A strains. PCR specific to group B wild-type strains amplified all group A and group B strains but gave a 688-bp product for group B wild-type strains, a 279-bp product for 2B strains, a 547-bp product for all group A strains, and an additional 688-bp product for some group A strains, including 3A strains. These types of PCR assays can, in conjunction with other methods, be used to efficiently distinguish candidate vaccine strains from other respiratory syncytial virus strains. PMID:8789010

Non-dairy probiotic beverages: the next step into human health.

PubMed

Gawkowski, D; Chikindas, M L

2013-06-01

Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit to the host. The two main genera of microorganisms indicated as sources of probiotic bacteria are Lactobacillus and Bifidobacterium. Historically used to produce fermented dairy products, certain strains of both genera are increasingly utilised to formulate other functional foods. As the consumers' understanding of the role of probiotics in health grows, so does the popularity of food containing them. The result of this phenomenon is an increase in the number of probiotic foods available for public consumption, including a rapidly-emerging variety of probiotic-containing non-dairy beverages, which provide a convenient way to improve and maintain health. However, the composition of non-dairy probiotic beverages can pose specific challenges to the survival of the health conferring microorganisms. To overcome these challenges, strain selection and protection techniques play an integral part in formulating a stable product. This review discusses non-dairy probiotic beverages, characteristics of an optimal beverage, and commonly used probiotic strains, including spore-forming bacteria. It also examines the most recent developments in probiotic encapsulation technology with focus on nano-fibre formation as a means of protecting viable cells. Utilising bacteria's natural armour or creating barrier mechanisms via encapsulation technology will fuel development of stable non-dairy probiotic beverages.

Whole genome sequencing improved case ascertainment in an outbreak of Shiga toxin-producing Escherichia coli O157 associated with raw drinking milk.

PubMed

Butcher, H; Elson, R; Chattaway, M A; Featherstone, C A; Willis, C; Jorgensen, F; Dallman, T J; Jenkins, C; McLAUCHLIN, J; Beck, C R; Harrison, S

2016-10-01

Five cases of STEC O157 phage type (PT) 21/28 reported consumption of raw cows' drinking milk (RDM) produced at a dairy farm in the South West of England. STEC O157 PT21/28 was isolated from faecal specimens from milking cows on the implicated farm. Whole genome sequencing (WGS) showed that human and cattle isolates were the same strain. Further analysis of WGS data confirmed that sequences of isolates from an additional four cases (who did not report consumption of RDM when first questioned) fell within the same five single nucleotide polymorphism cluster as the initial five cases epidemiologically linked to the consumption of RDM. These four additional cases identified by WGS were investigated further and were, ultimately, associated with the implicated farm. The RDM outbreak strain encoded stx2a, which is associated with increased pathogenicity and severity of symptoms. Further epidemiological analysis showed that 70% of isolates within a wider cluster containing the outbreak strain were from cases residing in, or linked to, the same geographical region of England. During this RDM outbreak, use of WGS improved case ascertainment and provided insights into the evolution of a highly pathogenic clade of STEC O157 PT21/28 stx2a associated with the South West of England.

Urinary metabolomic fingerprinting after consumption of a probiotic strain in women with mastitis.

PubMed

Vázquez-Fresno, Rosa; Llorach, Rafael; Marinic, Jelena; Tulipani, Sara; Garcia-Aloy, Mar; Espinosa-Martos, Irene; Jiménez, Esther; Rodríguez, Juan Miguel; Andres-Lacueva, Cristina

2014-09-01

Infectious mastitis is a common condition among lactating women, with staphylococci and streptococci being the main aetiological agents. In this context, some lactobacilli strains isolated from breast milk appear to be particularly effective for treating mastitis and, therefore, constitute an attractive alternative to antibiotherapy. A (1)H NMR-based metabolomic approach was applied to detect metabolomic differences after consuming a probiotic strain (Lactobacillus salivarius PS2) in women with mastitis. 24h urine of women with lactational mastitis was collected at baseline and after 21 days of probiotic (PB) administration. Multivariate analysis (OSC-PLS-DA and hierarchical clustering) showed metabolome differences after PB treatment. The discriminant metabolites detected at baseline were lactose, and ibuprofen and acetaminophen (two pharmacological drugs commonly used for mastitis pain), while, after PB intake, creatine and the gut microbial co-metabolites hippurate and TMAO were detected. In addition, a voluntary desertion of the pharmacological drugs ibuprofen and acetaminophen was observed after probiotic administration. The application of NMR-based metabolomics enabled the identification of the overall effects of probiotic consumption among women suffering from mastitis and highlighted the potential of this approach in evaluating the outcomes of probiotics consumption. To our knowledge, this is the first time that this approach has been applied in women with mastitis during lactation. Copyright © 2014. Published by Elsevier Ltd.

Muscle fibre recruitment can respond to the mechanics of the muscle contraction.

PubMed

Wakeling, James M; Uehli, Katrin; Rozitis, Antra I

2006-08-22

This study investigates the motor unit recruitment patterns between and within muscles of the triceps surae during cycling on a stationary ergometer at a range of pedal speeds and resistances. Muscle activity was measured from the soleus (SOL), medial gastrocnemius (MG) and lateral gastrocnemius (LG) using surface electromyography (EMG) and quantified using wavelet and principal component analysis. Muscle fascicle strain rates were quantified using ultrasonography, and the muscle-tendon unit lengths were calculated from the segmental kinematics. The EMG intensities showed that the body uses the SOL relatively more for the higher-force, lower-velocity contractions than the MG and LG. The EMG spectra showed a shift to higher frequencies at faster muscle fascicle strain rates for MG: these shifts were independent of the level of muscle activity, the locomotor load and the muscle fascicle strain. These results indicated that a selective recruitment of the faster motor units occurred within the MG muscle in response to the increasing muscle fascicle strain rates. This preferential recruitment of the faster fibres for the faster tasks indicates that in some circumstances motor unit recruitment during locomotion can match the contractile properties of the muscle fibres to the mechanical demands of the contraction.

Effect of high strain rates on peak stress in a Zr-based bulk metallic glass

NASA Astrophysics Data System (ADS)

Sunny, George; Yuan, Fuping; Prakash, Vikas; Lewandowski, John

2008-11-01

The mechanical behavior of Zr41.25Ti13.75Cu12.5Ni10Be22.5 (LM-1) has been extensively characterized under quasistatic loading conditions; however, its mechanical behavior under dynamic loading conditions is currently not well understood. A Split-Hopkinson pressure bar (SHPB) and a single-stage gas gun are employed to characterize the mechanical behavior of LM-1 in the strain-rate regime of 102-105/s. The SHPB experiments are conducted with a tapered insert design to mitigate the effects of stress concentrations and preferential failure at the specimen-insert interface. The higher strain-rate plate-impact compression-and-shear experiments are conducted by impacting a thick tungsten carbide (WC) flyer plate with a sandwich sample comprising a thin bulk metallic glass specimen between two thicker WC target plates. Specimens employed in the SHPB experiments failed in the gage-section at a peak stress of approximately 1.8 GPa. Specimens in the high strain-rate plate-impact experiments exhibited a flow stress in shear of approximately 0.9 GPa, regardless of the shear strain-rate. The flow stress under the plate-impact conditions was converted to an equivalent flow stress under uniaxial compression by assuming a von Mises-like material behavior and accounting for the plane strain conditions. The results of these experiments, when compared to the previous work conducted at quasistatic loading rates, indicate that the peak stress of LM-1 is essentially strain rate independent over the strain-rate range up to 105/s.

The zoonotic potential of avian influenza viruses isolated from wild waterfowl in Zambia.

PubMed

Simulundu, Edgar; Nao, Naganori; Yabe, John; Muto, Nilton A; Sithebe, Thami; Sawa, Hirofumi; Manzoor, Rashid; Kajihara, Masahiro; Muramatsu, Mieko; Ishii, Akihiro; Ogawa, Hirohito; Mweene, Aaron S; Takada, Ayato

2014-10-01

Whilst remarkable progress in elucidating the mechanisms governing interspecies transmission and pathogenicity of highly pathogenic avian influenza viruses (AIVs) has been made, similar studies focusing on low-pathogenic AIVs isolated from the wild waterfowl reservoir are limited. We previously reported that two AIV strains (subtypes H6N2 and H3N8) isolated from wild waterfowl in Zambia harbored some amino acid residues preferentially associated with human influenza virus proteins (so-called human signatures) and replicated better in the lungs of infected mice and caused more morbidity than a strain lacking such residues. To further substantiate these observations, we infected chickens and mice intranasally with AIV strains of various subtypes (H3N6, H3N8, H4N6, H6N2, H9N1 and H11N9) isolated from wild waterfowl in Zambia. Although some strains induced seroconversion, all of the tested strains replicated poorly and were nonpathogenic for chickens. In contrast, most of the strains having human signatures replicated well in the lungs of mice, and one of these strains caused severe illness in mice and induced lung injury that was characterized by a severe accumulation of polymorphonuclear leukocytes. These results suggest that some strains tested in this study may have the potential to infect mammalian hosts directly without adaptation, which might possibly be associated with the possession of human signature residues. Close monitoring and evaluation of host-associated signatures may help to elucidate the prevalence and emergence of AIVs with potential for causing zoonotic infections.

Virulence and extended-spectrum β-lactamase encoding genes in Escherichia coli recovered from chicken meat intended for hospitalized human consumption.

PubMed

Younis, Gamal A; Elkenany, Rasha M; Fouda, Mohamed A; Mostafa, Noura F

2017-10-01

This study describes the prevalence of Escherichia coli in frozen chicken meat intended for human consumption with emphasis on their virulence determinants through detection of the virulence genes and recognition of the extended-spectrum β-lactamase (ESBL) encoding genes ( bla OXA and bla TEM genes). A total of 120 frozen chicken meat samples were investigated for isolation of E. coli . All isolates were subjected to biochemical and serological tests. Eight serotypes isolated from samples were analyzed for the presence of various virulence genes ( stx1, stx2 , and eae A genes) using multiplex polymerase chain reaction (PCR) technique. Moreover, the strains were evaluated for the ESBL encoding genes ( bla TEM and bla OXA ). Overall, 11.66% (14/120) chicken meat samples carried E. coli according to cultural and biochemical properties. The most predominant serotypes were O78 and O128: H2 (21.5%, each), followed by O121: H7 and O44: H18. Molecular method detected that 2 strains (25%) harbored stx1 , 3 strains (37.5%) stx2 , and 3 strains (37.5%) both stx1 and stx2 , while 1 (12.5%) strain carried eae A gene. Particularly, only O26 serotype had all tested virulence genes ( stx1, stx2, and eae A ). The results revealed that all examined 8 serotypes were Shiga toxin-producing E. coli (STEC). The ESBL encoding genes ( bla TEM and bla OXA ) of STEC were detected in 4 (50%) isolates by multiplex PCR. The overall incidence of bla TEM and bla OXA genes was 3 (37.5%) and 2 (25%) isolates. The present study indicates the prevalence of virulent and ESBL-producing E. coli in frozen chicken meat intended for hospitalized human consumption due to poor hygienic measures and irregular use of antibiotics. Therefore, the basic instructions regarding good hygienic measures should be adapted to limit public health hazard.

Characterization and expression profiling of ATP-binding cassette transporter genes in the diamondback moth, Plutella xylostella (L.).

PubMed

Qi, Weiping; Ma, Xiaoli; He, Weiyi; Chen, Wei; Zou, Mingmin; Gurr, Geoff M; Vasseur, Liette; You, Minsheng

2016-09-27

ATP-binding cassette (ABC) transporters are one of the major transmembrane protein families found in all organisms and play important roles in transporting a variety of compounds across intra and extra cellular membranes. In some species, ABC transporters may be involved in the detoxification of substances such as insecticides. The diamondback moth, Plutella xylostella (L.), a destructive pest of cruciferous crops worldwide, is an important species to study as it is resistant to many types of insecticides as well as biological control Bacillus thuringiensis toxins. A total of 82 ABC genes were identified from our published P. xylostella genome, and grouped into eight subfamilies (ABCA-H) based on phylogenetic analysis. Genes of subfamilies ABCA, ABCC and ABCH were found to be expanded in P. xylostella compared with those in Bombyx mori, Manduca sexta, Heliconius melpomene, Danaus plexippus, Drosophila melanogaster, Tetranychus urticae and Homo sapiens. Phylogenetic analysis indicated that many of the ABC transporters in P. xylostella are orthologous to the well-studied ABC transporter genes in the seven other species. Transcriptome- and qRT-PCR-based analysis elucidated physiological effects of ABC gene expressions of P. xylostella which were developmental stage- and tissue-specific as well as being affected by whether or not the insects were from an insecticide-resistant strain. Two ABCC and one ABCA genes were preferentially expressed in midgut of the 4th-instar larvae of a susceptible strain (Fuzhou-S) suggesting their potential roles in metabolizing plant defensive chemicals. Most of the highly expressed genes in insecticide-resistant strains were also predominantly expressed in the tissues of Malpighian tubules and midgut. This is the most comprehensive study on identification, characterization and expression profiling of ABC transporter genes in P. xylostella to date. The diversified features and expression patterns of this gene family may be associated with the evolutionary capacity of this species to develop resistance to a wide range of insecticides and biological toxins. Our findings provide a solid foundation for future functional studies on specific ABC transporter genes in P. xylostella, and for further understanding of their physiological roles and regulatory pathways in insecticide resistance.

Method and means for separating and classifying superconductive particles

DOEpatents

Park, Jin Y.; Kearney, Robert J.

1991-01-01

The specification and drawings describe a series of devices and methods for classifying and separating superconductive particles. The superconductive particles may be separated from non-superconductive particles, and the superconductive particles may be separated by degrees of susceptibility to the Meissner effect force. The particles may also be simultaneously separated by size or volume and mass to obtain substantially homogeneous groups of particles. The separation techniques include levitation, preferential sedimentation and preferential concentration. Multiple separation vector forces are disclosed.

Engineering Pseudomonas putida KT2440 for Efficient Ethylene Glycol Utilization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beckham, Gregg T; Franden, Mary A; Thelhawadigedara, Lahiru Niroshan Jayakody

Ethylene glycol is used as a raw material in the production of polyethylene terephthalate, in antifreeze, as a gas hydrate inhibitor in pipelines, and for many other industrial applications. It is metabolized by aerobic microbial processes via the highly toxic intermediates glycolaldehyde and glycolate through C2 metabolic pathways. Pseudomonas putida KT2440, which has been engineered for environmental remediation applications given its high toxicity tolerance and broad substrate specificity, is not able to efficiently metabolize ethylene glycol, despite harboring putative genes for this purpose. To further expand the metabolic portfolio of P. putida, we elucidated the metabolic pathway to enable ethylenemore » glycol via systematic overexpression of glyoxylate carboligase (gcl) in combination with other genes. Quantitative reverse transcription polymerase chain reaction demonstrated that all of the four genes in genomic proximity to gcl (hyi, glxR, ttuD, and pykF) are transcribed as an operon. Where the expression of only two genes (gcl and glxR) resulted in growth in ethylene glycol, improved growth and ethylene glycol utilization were observed when the entire gcl operon was expressed. Both glycolaldehyde and glyoxal inhibit growth in concentrations of ethylene glycol above 50 mM. To overcome this bottleneck, the additional overexpression of the glycolate oxidase (glcDEF) operon removes the glycolate bottleneck and minimizes the production of these toxic intermediates, permitting growth in up to 2 M (~124 g/L) and complete consumption of 0.5 M (31 g/L) ethylene glycol in shake flask experiments. In addition, the engineered strain enables conversion of ethylene glycol to medium-chain-length polyhydroxyalkanoates (mcl-PHAs). Overall, this study provides a robust P. putida KT2440 strain for ethylene glycol consumption, which will serve as a foundational strain for further biocatalyst development for applications in the remediation of waste polyester plastics and biomass-derived wastewater streams.« less

Risk Factors for Campylobacteriosis of Chicken, Ruminant, and Environmental Origin: A Combined Case-Control and Source Attribution Analysis

PubMed Central

Wagenaar, Jaap A.; de Boer, Albert G.; Havelaar, Arie H.; Friesema, Ingrid H. M.; French, Nigel P.; Busani, Luca; van Pelt, Wilfrid

2012-01-01

Background Campylobacteriosis contributes strongly to the disease burden of food-borne pathogens. Case-control studies are limited in attributing human infections to the different reservoirs because they can only trace back to the points of exposure, which may not point to the original reservoirs because of cross-contamination. Human Campylobacter infections can be attributed to specific reservoirs by estimating the extent of subtype sharing between strains from humans and reservoirs using multilocus sequence typing (MLST). Methodology/Principal Findings We investigated risk factors for human campylobacteriosis caused by Campylobacter strains attributed to different reservoirs. Sequence types (STs) were determined for 696 C. jejuni and 41 C. coli strains from endemic human cases included in a case-control study. The asymmetric island model, a population genetics approach for modeling Campylobacter evolution and transmission, attributed these cases to four putative animal reservoirs (chicken, cattle, sheep, pig) and to the environment (water, sand, wild birds) considered as a proxy for other unidentified reservoirs. Most cases were attributed to chicken (66%) and cattle (21%), identified as the main reservoirs in The Netherlands. Consuming chicken was a risk factor for campylobacteriosis caused by chicken-associated STs, whereas consuming beef and pork were protective. Risk factors for campylobacteriosis caused by ruminant-associated STs were contact with animals, barbecuing in non-urban areas, consumption of tripe, and never/seldom chicken consumption. Consuming game and swimming in a domestic swimming pool during springtime were risk factors for campylobacteriosis caused by environment-associated STs. Infections with chicken- and ruminant-associated STs were only partially explained by food-borne transmission; direct contact and environmental pathways were also important. Conclusion/Significance This is the first case-control study in which risk factors for campylobacteriosis are investigated in relation to the attributed reservoirs based on MLST profiles. Combining epidemiological and source attribution data improved campylobacteriosis risk factor identification and characterization, generated hypotheses, and showed that genotype-based source attribution is epidemiologically sensible. PMID:22880049

Engineering Pseudomonas putida KT2440 for efficient ethylene glycol utilization.

PubMed

Franden, Mary Ann; Jayakody, Lahiru N; Li, Wing-Jin; Wagner, Neil J; Cleveland, Nicholas S; Michener, William E; Hauer, Bernhard; Blank, Lars M; Wierckx, Nick; Klebensberger, Janosch; Beckham, Gregg T

2018-06-07

Ethylene glycol is used as a raw material in the production of polyethylene terephthalate, in antifreeze, as a gas hydrate inhibitor in pipelines, and for many other industrial applications. It is metabolized by aerobic microbial processes via the highly toxic intermediates glycolaldehyde and glycolate through C2 metabolic pathways. Pseudomonas putida KT2440, which has been engineered for environmental remediation applications given its high toxicity tolerance and broad substrate specificity, is not able to efficiently metabolize ethylene glycol, despite harboring putative genes for this purpose. To further expand the metabolic portfolio of P. putida, we elucidated the metabolic pathway to enable ethylene glycol via systematic overexpression of glyoxylate carboligase (gcl) in combination with other genes. Quantitative reverse transcription polymerase chain reaction demonstrated that all of the four genes in genomic proximity to gcl (hyi, glxR, ttuD, and pykF) are transcribed as an operon. Where the expression of only two genes (gcl and glxR) resulted in growth in ethylene glycol, improved growth and ethylene glycol utilization were observed when the entire gcl operon was expressed. Both glycolaldehyde and glyoxal inhibit growth in concentrations of ethylene glycol above 50 mM. To overcome this bottleneck, the additional overexpression of the glycolate oxidase (glcDEF) operon removes the glycolate bottleneck and minimizes the production of these toxic intermediates, permitting growth in up to 2 M (~124 g/L) and complete consumption of 0.5 M (31 g/L) ethylene glycol in shake flask experiments. In addition, the engineered strain enables conversion of ethylene glycol to medium-chain-length polyhydroxyalkanoates (mcl-PHAs). Overall, this study provides a robust P. putida KT2440 strain for ethylene glycol consumption, which will serve as a foundational strain for further biocatalyst development for applications in the remediation of waste polyester plastics and biomass-derived wastewater streams. Copyright © 2018. Published by Elsevier Inc.

The new allelic variant of the subtilase cytotoxin (subAB2) is common among Shiga toxin-producing Escherichia coli strains from large game animals and their meat and meat products.

PubMed

Sánchez, Sergio; Díaz-Sánchez, Sandra; Martínez, Remigio; Llorente, María Teresa; Herrera-León, Silvia; Vidal, Dolors

2013-10-25

Subtilase cytotoxin (SubAB) is an AB5 toxin produced by Shiga toxin (Stx)-producing Escherichia coli (STEC) strains usually lacking the eae gene product intimin. Two allelic variants of SubAB encoding genes have been described: subAB1, located on a plasmid, and subAB2, located on a pathogenicity island (PAI) together with tia gene. While subAB1 has been reported to be more frequent among bovine strains, subAB2 has been mainly associated with strains from small ruminants. We investigated the presence of the two variants of subAB among 59 eae-negative STEC from large game animals (deer and wild boar) and their meat and meat products in order to assess the role of other species in the epidemiology of subAB-positive, eae-negative STEC. For this approach, the strains were PCR-screened for the presence of subAB, including the specific detection of both allelic variants, for the presence of saa, tia and sab, and for stx subtyping. Overall, subAB genes were detected in 71.2% of the strains: 84.1% of the strains from deer and 33.3% of the strains from wild boar. Most of them (97.6%) possessed subAB2 and most of these subAB2-positive strains (92.7%) were also positive for tia and negative for saa, suggesting the presence of the subAB2-harbouring PAI. Subtype stx2b was present in most of the strains (67.8%) and a statistically significant association could be established between subAB2 and stx2b. Our results suggest that large game animals, mainly deer, may represent an important animal reservoir of subAB2-positive, eae-negative STEC, and also highlight the risk of human infection posed by the consumption of large game meat and meat products. Copyright © 2013 Elsevier B.V. All rights reserved.

Identification of candidate genes affecting Δ9-tetrahydrocannabinol biosynthesis in Cannabis sativa

PubMed Central

Marks, M. David; Tian, Li; Wenger, Jonathan P.; Omburo, Stephanie N.; Soto-Fuentes, Wilfredo; He, Ji; Gang, David R.; Weiblen, George D.; Dixon, Richard A.

2009-01-01

RNA isolated from the glands of a Δ9-tetrahydrocannabinolic acid (THCA)-producing strain of Cannabis sativa was used to generate a cDNA library containing over 100 000 expressed sequence tags (ESTs). Sequencing of over 2000 clones from the library resulted in the identification of over 1000 unigenes. Candidate genes for almost every step in the biochemical pathways leading from primary metabolites to THCA were identified. Quantitative PCR analysis suggested that many of the pathway genes are preferentially expressed in the glands. Hexanoyl-CoA, one of the metabolites required for THCA synthesis, could be made via either de novo fatty acids synthesis or via the breakdown of existing lipids. qPCR analysis supported the de novo pathway. Many of the ESTs encode transcription factors and two putative MYB genes were identified that were preferentially expressed in glands. Given the similarity of the Cannabis MYB genes to those in other species with known functions, these Cannabis MYBs may play roles in regulating gland development and THCA synthesis. Three candidates for the polyketide synthase (PKS) gene responsible for the first committed step in the pathway to THCA were characterized in more detail. One of these was identical to a previously reported chalcone synthase (CHS) and was found to have CHS activity. All three could use malonyl-CoA and hexanoyl-CoA as substrates, including the CHS, but reaction conditions were not identified that allowed for the production of olivetolic acid (the proposed product of the PKS activity needed for THCA synthesis). One of the PKS candidates was highly and specifically expressed in glands (relative to whole leaves) and, on the basis of these expression data, it is proposed to be the most likely PKS responsible for olivetolic acid synthesis in Cannabis glands. PMID:19581347

Identification of a Pair of Phospholipid:Diacylglycerol Acyltransferases from Developing Flax (Linum usitatissimum L.) Seed Catalyzing the Selective Production of Trilinolenin*

PubMed Central

Pan, Xue; Siloto, Rodrigo M. P.; Wickramarathna, Aruna D.; Mietkiewska, Elzbieta; Weselake, Randall J.

2013-01-01

The oil from flax (Linum usitatissimum L.) has high amounts of α-linolenic acid (ALA; 18:3cisΔ9,12,15) and is one of the richest sources of omega-3 polyunsaturated fatty acids (ω-3-PUFAs). To produce ∼57% ALA in triacylglycerol (TAG), it is likely that flax contains enzymes that can efficiently transfer ALA to TAG. To test this hypothesis, we conducted a systematic characterization of TAG-synthesizing enzymes from flax. We identified several genes encoding acyl-CoA:diacylglycerol acyltransferases (DGATs) and phospholipid:diacylglycerol acyltransferases (PDATs) from the flax genome database. Due to recent genome duplication, duplicated gene pairs have been identified for all genes except DGAT2-2. Analysis of gene expression indicated that two DGAT1, two DGAT2, and four PDAT genes were preferentially expressed in flax embryos. Yeast functional analysis showed that DGAT1, DGAT2, and two PDAT enzymes restored TAG synthesis when produced recombinantly in yeast H1246 strain. The activity of particular PDAT enzymes (LuPDAT1 and LuPDAT2) was stimulated by the presence of ALA. Further seed-specific expression of flax genes in Arabidopsis thaliana indicated that DGAT1, PDAT1, and PDAT2 had significant effects on seed oil phenotype. Overall, this study indicated the existence of unique PDAT enzymes from flax that are able to preferentially catalyze the synthesis of TAG containing ALA acyl moieties. The identified LuPDATs may have practical applications for increasing the accumulation of ALA and other polyunsaturated fatty acids in oilseeds for food and industrial applications. PMID:23824186

76 FR 76743 - Government-Owned Inventions; Licensing and Collaborative Research Opportunity: Chemotoxins for...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-08

...; Licensing and Collaborative Research Opportunity: Chemotoxins for Targeted Treatment of Diseased Cells... (aka ``chemotoxins'') to preferentially and specifically eliminate chemokine receptor-expressing cells... used to cause inflammation to specifically target immune cells to increase immunogenicity for malignant...

Phenotypic and genotypic description of Sedimenticola selenatireducens strain CUZ, a marine (per)chlorate-respiring gammaproteobacterium, and its close relative the chlorate-respiring Sedimenticola strain NSS.

PubMed

Carlström, Charlotte I; Loutey, Dana E; Wang, Ouwei; Engelbrektson, Anna; Clark, Iain; Lucas, Lauren N; Somasekhar, Pranav Y; Coates, John D

2015-04-01

Two (per)chlorate-reducing bacteria, strains CUZ and NSS, were isolated from marine sediments in Berkeley and San Diego, CA, respectively. Strain CUZ respired both perchlorate and chlorate [collectively designated (per)chlorate], while strain NSS respired only chlorate. Phylogenetic analysis classified both strains as close relatives of the gammaproteobacterium Sedimenticola selenatireducens. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) preparations showed the presence of rod-shaped, motile cells containing one polar flagellum. Optimum growth for strain CUZ was observed at 25 to 30 °C, pH 7, and 4% NaCl, while strain NSS grew optimally at 37 to 42 °C, pH 7.5 to 8, and 1.5 to 2.5% NaCl. Both strains oxidized hydrogen, sulfide, various organic acids, and aromatics, such as benzoate and phenylacetate, as electron donors coupled to oxygen, nitrate, and (per)chlorate or chlorate as electron acceptors. The draft genome of strain CUZ carried the requisite (per)chlorate reduction island (PRI) for (per)chlorate respiration, while that of strain NSS carried the composite chlorate reduction transposon responsible for chlorate metabolism. The PRI of strain CUZ encoded a perchlorate reductase (Pcr), which reduced both perchlorate and chlorate, while the genome of strain NSS included a gene for a distinct chlorate reductase (Clr) that reduced only chlorate. When both (per)chlorate and nitrate were present, (per)chlorate was preferentially utilized if the inoculum was pregrown on (per)chlorate. Historically, (per)chlorate-reducing bacteria (PRB) and chlorate-reducing bacteria (CRB) have been isolated primarily from freshwater, mesophilic environments. This study describes the isolation and characterization of two highly related marine halophiles, one a PRB and the other a CRB, and thus broadens the known phylogenetic and physiological diversity of these unusual metabolisms. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Cun; Aoun, Bachir; Cui, Lishan

Microstructure evolution of a cold-drawn NiTi shape memory alloy wire was investigated by means of in-situ synchrotron high-energy X-ray diffraction during continuous heating. The cold-drawn wire contained amorphous regions and nano-crystalline domains in its microstructure. Pair distribution function analysis revealed that the amorphous regions underwent structural relaxation via atomic rearrangement when heated above 100 °C. The nano-crystalline domains were found to exhibit a strong cold work induced lattice strain anisotropy having a preferential <111> fiber orientation along the wire axial direction. The lattice strain anisotropy systematically decreased upon heating above 200 °C, implying a structural recovery. A broad conical texturemore » was formed in the wire specimen after crystallization similar in detail to the initial <111> texture axial orientation of the nano-crystalline domains produced by the severe cold wire drawing deformation.« less

Strain Sensors, Methods of Making Same, and Applications of Same

NASA Technical Reports Server (NTRS)

Hatfield, Walter (Inventor); Biris, Alexandru S. (Inventor); Trigwell, Steven (Inventor)

2015-01-01

In one aspect, the present invention relates to a layered structure usable in a strain sensor. In one embodiment, the layered structure has a substrate with a first surface and an opposite, second surface defining a body portion therebetween; and a film of carbon nanotubes deposited on the first surface of the substrate, wherein the film of carbon nanotubes is conductive and characterized with an electrical resistance. In one embodiment, the carbon nanotubes are aligned in a preferential direction. In one embodiment, the carbon nanotubes are formed in a yarn such that any mechanical stress increases their electrical response. In one embodiment, the carbon nanotubes are incorporated into a polymeric scaffold that is attached to the surface of the substrate. In one embodiment, the surfaces of the carbon nanotubes are functionalized such that its electrical conductivity is increased.

Strain sensors, methods of making same, and applications of same

DOEpatents

Biris, Alexandru S.; Trigwell, Steven; Hatfield, Walter

2015-06-30

In one aspect, the present invention relates to a layered structure usable in a strain sensor. In one embodiment, the layered structure has a substrate with a first surface and an opposite, second surface defining a body portion therebetween; and a film of carbon nanotubes deposited on the first surface of the substrate, wherein the film of carbon nanotubes is conductive and characterized with an electrical resistance. In one embodiment, the carbon nanotubes are aligned in a preferential direction. In one embodiment, the carbon nanotubes are formed in a yarn such that any mechanical stress increases their electrical response. In one embodiment, the carbon nanotubes are incorporated into a polymeric scaffold that is attached to the surface of the substrate. In one embodiment, the surfaces of the carbon nanotubes are functionalized such that its electrical conductivity is increased.

E. coli and colorectal cancer: a complex relationship that deserves a critical mindset.

PubMed

Wassenaar, Trudy M

2018-06-17

To the multiple factors that may eventually result in colorectal cancer (CRC), strains of E. coli have now been added, in particular strains producing colibactin from their polyketide synthesis (pks) locus. The evidence and mechanistic explanations for this unfortunate effect of what is in most cases a harmless commensal are discussed in the first part of this review. In the second part, observations are presented and discussed that do not fit with the hypothesis that colibactin-producing E. coli produce CRC. The last part of this review is reserved for an alternative explanation of the function of this enigmatic colibactin, a toxin that has not yet been isolated. It is hypothesized that E. coli preferentially colonizes cancerous lesions as an effect rather than a cause and that colibactin production provides a selective advantage to compete with other bacteria.

Impact of geographical origin on mating behaviour in two species of Biomphalaria (Planorbidae: Gastropoda).

PubMed

Rupp, J C; Woolhouse, M E

1999-12-01

Studies of inbreeding and outcrossing have traditionally concentrated on matings within populations. The influence of geographical origin on mate choice in animals from different populations has received less attention. We investigated whether planorbid snails mated preferentially within their own population or with snails from other populations. Snails from three Biomphalaria pfeifferi strains and three B. glabrata strains were allowed to mate with conspecifics in the laboratory. We recorded their matings at night using time-lapse video. When they could choose between sympatric and allopatric snails, Biomphalaria snails significantly preferred the former: snails of each population mated more often with sympatric than with allopatric snails. This tendency to avoid outcrossing may indicate that, in some species, local adaptations can be more valuable than genetic novelties. Copyright 1999 The Association for the Study of Animal Behaviour.

Clinical Trials with Oncolytic Measles Virus: Current Status and Future Prospects.

PubMed

Msaouel, Pavlos; Opyrchal, Mateusz; Dispenzieri, Angela; Peng, Kah Whye; Federspiel, Mark J; Russell, Stephen J; Galanis, Evanthia

2018-01-01

Attenuated Edmonston lineage measles virus (MV-Edm) vaccine strains can preferentially infect and lyse a wide variety of cancer cells. Oncolytic MV-Edm derivatives are genetically engineered to express the human carcinoembryonic antigen (MV-CEA virus) or the human sodium iodide symporter (MV-NIS virus) and are currently being tested in clinical trials against ovarian cancer, glioblastoma multiforme, multiple myeloma, mesothelioma, head and neck cancer, breast cancer and malignant peripheral nerve sheath tumors. This review describes the basic and preclinical data that facilitated the clinical translation of MV-Edm strains, and summarizes the clinical results of this oncolytic platform to date. Furthermore, we discuss the latest clinically relevant MV-Edm vector developments and creative strategies for future translational steps. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Transposable Elements versus the Fungal Genome: Impact on Whole-Genome Architecture and Transcriptional Profiles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castanera, Raul; Lopez-Varas, Leticia; Borgognone, Alessandra

Transposable elements (TEs) are exceptional contributors to eukaryotic genome diversity. Their ubiquitous presence impacts the genomes of nearly all species and mediates genome evolution by causing mutations and chromosomal rearrangements and by modulating gene expression. We performed an exhaustive analysis of the TE content in 18 fungal genomes, including strains of the same species and species of the same genera. Our results depicted a scenario of exceptional variability, with species having 0.02 to 29.8% of their genome consisting of transposable elements. A detailed analysis performed on two strains of Pleurotus ostreatus uncovered a genome that is populated mainly by Classmore » I elements, especially LTR-retrotransposons amplified in recent bursts from 0 to 2 million years (My) ago. The preferential accumulation of TEs in clusters led to the presence of genomic regions that lacked intra- and inter-specific conservation. In addition, we investigated the effect of TE insertions on the expression of their nearby upstream and downstream genes. Our results showed that an important number of genes under TE influence are significantly repressed, with stronger repression when genes are localized within transposon clusters. Our transcriptional analysis performed in four additional fungal models revealed that this TE-mediated silencing was present only in species with active cytosine methylation machinery. We hypothesize that this phenomenon is related to epigenetic defense mechanisms that are aimed to suppress TE expression and control their proliferation.« less

Transposable Elements versus the Fungal Genome: Impact on Whole-Genome Architecture and Transcriptional Profiles

DOE PAGES

Castanera, Raul; Lopez-Varas, Leticia; Borgognone, Alessandra; ...

2016-06-13

Transposable elements (TEs) are exceptional contributors to eukaryotic genome diversity. Their ubiquitous presence impacts the genomes of nearly all species and mediates genome evolution by causing mutations and chromosomal rearrangements and by modulating gene expression. We performed an exhaustive analysis of the TE content in 18 fungal genomes, including strains of the same species and species of the same genera. Our results depicted a scenario of exceptional variability, with species having 0.02 to 29.8% of their genome consisting of transposable elements. A detailed analysis performed on two strains of Pleurotus ostreatus uncovered a genome that is populated mainly by Classmore » I elements, especially LTR-retrotransposons amplified in recent bursts from 0 to 2 million years (My) ago. The preferential accumulation of TEs in clusters led to the presence of genomic regions that lacked intra- and inter-specific conservation. In addition, we investigated the effect of TE insertions on the expression of their nearby upstream and downstream genes. Our results showed that an important number of genes under TE influence are significantly repressed, with stronger repression when genes are localized within transposon clusters. Our transcriptional analysis performed in four additional fungal models revealed that this TE-mediated silencing was present only in species with active cytosine methylation machinery. We hypothesize that this phenomenon is related to epigenetic defense mechanisms that are aimed to suppress TE expression and control their proliferation.« less

Insights into the history of a bacterial group II intron remnant from the genomes of the nitrogen-fixing symbionts Sinorhizobium meliloti and Sinorhizobium medicae.

PubMed

Toro, N; Martínez-Rodríguez, L; Martínez-Abarca, F

2014-10-01

Group II introns are self-splicing catalytic RNAs that act as mobile retroelements. In bacteria, they are thought to be tolerated to some extent because they self-splice and home preferentially to sites outside of functional genes, generally within intergenic regions or in other mobile genetic elements, by mechanisms including the divergence of DNA target specificity to prevent target site saturation. RmInt1 is a mobile group II intron that is widespread in natural populations of Sinorhizobium meliloti and was first described in the GR4 strain. Like other bacterial group II introns, RmInt1 tends to evolve toward an inactive form by fragmentation, with loss of the 3' terminus. We identified genomic evidence of a fragmented intron closely related to RmInt1 buried in the genome of the extant S. meliloti/S. medicae species. By studying this intron, we obtained evidence for the occurrence of intron insertion before the divergence of ancient rhizobial species. This fragmented group II intron has thus existed for a long time and has provided sequence variation, on which selection can act, contributing to diverse genetic rearrangements, and to generate pan-genome divergence after strain differentiation. The data presented here suggest that fragmented group II introns within intergenic regions closed to functionally important neighboring genes may have been microevolutionary forces driving adaptive evolution of these rhizobial species.

Insights into the history of a bacterial group II intron remnant from the genomes of the nitrogen-fixing symbionts Sinorhizobium meliloti and Sinorhizobium medicae

PubMed Central

Toro, N; Martínez-Rodríguez, L; Martínez-Abarca, F

2014-01-01

Group II introns are self-splicing catalytic RNAs that act as mobile retroelements. In bacteria, they are thought to be tolerated to some extent because they self-splice and home preferentially to sites outside of functional genes, generally within intergenic regions or in other mobile genetic elements, by mechanisms including the divergence of DNA target specificity to prevent target site saturation. RmInt1 is a mobile group II intron that is widespread in natural populations of Sinorhizobium meliloti and was first described in the GR4 strain. Like other bacterial group II introns, RmInt1 tends to evolve toward an inactive form by fragmentation, with loss of the 3′ terminus. We identified genomic evidence of a fragmented intron closely related to RmInt1 buried in the genome of the extant S. meliloti/S. medicae species. By studying this intron, we obtained evidence for the occurrence of intron insertion before the divergence of ancient rhizobial species. This fragmented group II intron has thus existed for a long time and has provided sequence variation, on which selection can act, contributing to diverse genetic rearrangements, and to generate pan-genome divergence after strain differentiation. The data presented here suggest that fragmented group II introns within intergenic regions closed to functionally important neighboring genes may have been microevolutionary forces driving adaptive evolution of these rhizobial species. PMID:24736785

Screening of Lactobacillus strains for their ability to produce conjugated linoleic acid in milk and to adhere to the intestinal tract.

PubMed

Sosa-Castañeda, J; Hernández-Mendoza, A; Astiazarán-García, H; Garcia, H S; Estrada-Montoya, M C; González-Córdova, A F; Vallejo-Cordoba, B

2015-10-01

Conjugated linoleic acid (CLA) has been shown to provide beneficial effects on health; however, the amount consumed in food is far from that required for the desired effects. Thus, increasing the CLA content in dairy foods through milk fermentation with specific lactic acid bacteria (LAB) offers an interesting alternative. Moreover, some LAB may be able to adhere to the intestinal mucosa and produce CLA through endogenous synthesis. Therefore, the objective of this study was to screen LAB isolates for their ability to produce CLA in skim milk and in simulated gastrointestinal conditions. Additionally, the ability of selected CLA-producing LAB to adhere to the intestinal mucosa in a murine model was assessed. Results showed that of 13 strains of Lactobacillus tested, only 4 were able to produce CLA in skim milk supplemented with linoleic acid (13.44 ± 0.78 to 50.9 ± 0.26 µg/mL). Furthermore, these 4 Lactobacillus strains were able to survive and produce CLA in simulated gastrointestinal conditions and to adhere to the intestinal mucosa of Wistar rats after 7 d of oral inoculation with fluorescently labeled bacteria. Accordingly, these 4 Lactobacillus strains may be used to manufacture fermented dairy foods to increase CLA content, and consumption of these fermented milks may result in CLA produced endogenously by these LAB. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Flunarizine Prevents Hepatitis C Virus Membrane Fusion in a Genotype-dependent Manner by Targeting the Potential Fusion Peptide within E1

PubMed Central

Perin, Paula M.; Haid, Sibylle; Brown, Richard J. P.; Doerrbecker, Juliane; Schulze, Kai; Zeilinger, Carsten; von Schaewen, Markus; Heller, Brigitte; Vercauteren, Koen; Luxenburger, Eva; Baktash, Yasmine M.; Vondran, Florian W. R.; Speerstra, Sietkse; Awadh, Abdullah; Mukhtarov, Furkat; Schang, Luis M; Kirschning, Andreas; Müller, Rolf; Guzman, Carlos A.; Kaderali, Lars; Randall, Glenn; Meuleman, Philip; Ploss, Alexander; Pietschmann, Thomas

2015-01-01

To explore mechanisms of hepatitis C virus (HCV) replication we screened a compound library including licensed drugs. Flunarizine, a diphenylmethylpiperazine used to treat migraine, inhibited HCV cell entry in vitro and in vivo in a genotype-dependent fashion. Analysis of mosaic viruses between susceptible and resistant strains revealed that E1 and E2 glycoproteins confer susceptibility to flunarizine. Time of addition experiments and single particle tracking of HCV demonstrated that flunarizine specifically prevents membrane fusion. Related phenothiazines and pimozide also inhibited HCV infection and preferentially targeted HCV genotype 2 viruses. However, phenothiazines and pimozide exhibited improved genotype coverage including the difficult to treat genotype 3. Flunarizine-resistant HCV carried mutations within the alleged fusion peptide and displayed cross-resistance to these compounds, indicating that these drugs have a common mode of action. Conclusion: These observations reveal novel details about HCV membrane fusion. Moreover, flunarizine and related compounds represent first-in-class HCV fusion inhibitors that merit consideration for repurposing as cost-effective component of HCV combination therapies. PMID:26248546

Engineering industrial Saccharomyces cerevisiae strains for xylose fermentation and comparison for switchgrass conversion.

PubMed

Hector, Ronald E; Dien, Bruce S; Cotta, Michael A; Qureshi, Nasib

2011-09-01

Saccharomyces' physiology and fermentation-related properties vary broadly among industrial strains used to ferment glucose. How genetic background affects xylose metabolism in recombinant Saccharomyces strains has not been adequately explored. In this study, six industrial strains of varied genetic background were engineered to ferment xylose by stable integration of the xylose reductase, xylitol dehydrogenase, and xylulokinase genes. Aerobic growth rates on xylose were 0.04-0.17 h(-1). Fermentation of xylose and glucose/xylose mixtures also showed a wide range of performance between strains. During xylose fermentation, xylose consumption rates were 0.17-0.31 g/l/h, with ethanol yields 0.18-0.27 g/g. Yields of ethanol and the metabolite xylitol were positively correlated, indicating that all of the strains had downstream limitations to xylose metabolism. The better-performing engineered and parental strains were compared for conversion of alkaline pretreated switchgrass to ethanol. The engineered strains produced 13-17% more ethanol than the parental control strains because of their ability to ferment xylose.

The anomalous depolarization anisotropy in the central backscattering area for turbid medium with Mie scatterers

NASA Astrophysics Data System (ADS)

Wang, Xuezhen; Lai, Jiancheng; Song, Yang; Li, Zhenhua

2018-05-01

It is generally recognized that circularly polarized light is preferentially maintained over linearly polarized light in turbid medium with Mie scatterers. However, in this work, the anomalous depolarization anisotropy is reported in the backscattering area near the point of illumination. Both experimental and Monte Carlo simulations show preferential retention of linear polarization states compared to circular polarization states in a specific backscattering area. Further analysis indicates that the anomalous depolarization behavior in the specific area is induced by lateral scattering events, which own low circular polarization memory. In addition, it is also found that the size of the anomalous depolarization area is related to the transport mean free path of the turbid medium.

bmp15l, figla, smc1bl, and larp6l are preferentially expressed in germ cells in Atlantic salmon (Salmo salar L.).

PubMed

Kleppe, Lene; Edvardsen, Rolf Brudvik; Furmanek, Tomasz; Andersson, Eva; Juanchich, Amélie; Wargelius, Anna

2017-01-01

Atlantic salmon is a valuable commercial aquaculture species that would benefit economically and environmentally by controlling precocious puberty and preventing escapees from reproducing with wild populations. One solution to both these challenges is the production of sterile individuals by inhibiting the formation of germ cells, but achieving this requires more information on the specific factors that control germ cell formation. Here, we identified and characterized novel factors that are preferentially expressed in Atlantic salmon germ cells by screening for gonad-specific genes using available adult multi-tissue transcriptomes. We excluded genes with expression in tissues other than gonads based on quantity of reads, and then a subset of genes was selected for verification in a multi-tissue PCR screen. Four gonad-specific genes (bmp15l, figla, smc1bl, and larp6l) were chosen for further characterization, namely: germ cell specificity, investigated by comparing mRNA abundance in wild-type and germ cell-free gonads by quantitative real-time PCR, and cellular location, visualized by in situ hybridization. All four genes were expressed in both testis and ovary, and preferentially within the germ cells of both sexes. These genes may be essential players in salmon germ cell development, and could be important for future studies aiming to understand and control reproduction. Mol. Reprod. Dev. 84: 76-87, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Sequence and structure determinants of Drosophila Hsp70 mRNA translation: 5'UTR secondary structure specifically inhibits heat shock protein mRNA translation.

PubMed Central

Hess, M A; Duncan, R F

1996-01-01

Preferential translation of Drosophila heat shock protein 70 (Hsp70) mRNA requires only the 5'-untranslated region (5'-UTR). The sequence of this region suggests that it has relatively little secondary structure, which may facilitate efficient protein synthesis initiation. To determine whether minimal 5'-UTR secondary structure is required for preferential translation during heat shock, the effect of introducing stem-loops into the Hsp70 mRNA 5'-UTR was measured. Stem-loops of -11 kcal/mol abolished translation during heat shock, but did not reduce translation in non-heat shocked cells. A -22 kcal/mol stem-loop was required to comparably inhibit translation during growth at normal temperatures. To investigate whether specific sequence elements are also required for efficient preferential translation, deletion and mutation analyses were conducted in a truncated Hsp70 5'-UTR containing only the cap-proximal and AUG-proximal segments. Linker-scanner mutations in the cap-proximal segment (+1 to +37) did not impair translation. Re-ordering the segments reduced mRNA translational efficiency by 50%. Deleting the AUG-proximal segment severely inhibited translation. A 5-extension of the full-length leader specifically impaired heat shock translation. These results indicate that heat shock reduces the capacity to unwind 5-UTR secondary structure, allowing only mRNAs with minimal 5'-UTR secondary structure to be efficiently translated. A function for specific sequences is also suggested. PMID:8710519

Selective elimination of neuroblastoma cells by synergistic effect of Akt kinase inhibitor and tetrathiomolybdate.

PubMed

Navrátilová, Jarmila; Karasová, Martina; Kohutková Lánová, Martina; Jiráková, Ludmila; Budková, Zuzana; Pacherník, Jiří; Šmarda, Jan; Beneš, Petr

2017-09-01

Neuroblastoma is the most common extracranial solid tumour of infancy. Pathological activation of glucose consumption, glycolysis and glycolysis-activating Akt kinase occur frequently in neuroblastoma cells, and these changes correlate with poor prognosis of patients. Therefore, several inhibitors of glucose utilization and the Akt kinase activity are in preclinical trials as potential anti-cancer drugs. However, metabolic plasticity of cancer cells might undermine efficacy of this approach. In this work, we identified oxidative phosphorylation as compensatory mechanism preserving viability of neuroblastoma cells with inhibited glucose uptake/Akt kinase. It was oxidative phosphorylation that maintained intracellular level of ATP and proliferative capacity of these cells. The oxidative phosphorylation inhibitors (rotenone, tetrathiomolybdate) synergized with inhibitor of the Akt kinase/glucose uptake in down-regulation of both viability of neuroblastoma cells and clonogenic potential of cells forming neuroblastoma spheroids. Interestingly, tetrathiomolybdate acted as highly specific inhibitor of oxygen consumption and activator of lactate production in neuroblastoma cells, but not in normal fibroblasts and neuronal cells. Moreover, the reducing effect of tetrathiomolybdate on cell viability and the level of ATP in the cells with inhibited Akt kinase/glucose uptake was also selective for neuroblastoma cells. Therefore, efficient elimination of neuroblastoma cells requires inhibition of both glucose uptake/Akt kinase and oxidative phosphorylation activities. The use of tetrathiomolybdate as a mitochondrial inhibitor contributes to selectivity of this combined treatment, preferentially targeting neuroblastoma cells. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Australian consumer awareness of health benefits associated with vegetable consumption.

PubMed

Rekhy, Reetica; Khan, Aila; Eason, Jocelyn; Mactavish-West, Hazel; Lister, Carolyn; Mcconchie, Robyn

2017-04-01

The present study investigated the perceived health benefits of specific vegetable consumption to guide the use of nutrition and health claims on vegetable marketing collateral. Free elicitation and consumer ranking data were collected through an online survey of 1000 adults from across Australia and analysed for the perceived importance of vegetables in the daily diet, number of serves consumed per day, knowledge about health-related benefits of specific vegetables and perceived health benefits of vegetable consumption. The importance of vegetables in the diet and daily vegetable consumption was higher in people from an English-speaking background, females, people aged 45 years and over and people living in non-metropolitan areas. Digestion was selected as the major health benefit from consumption of specific vegetables. However, understanding of the health benefits of specific vegetable consumption was relatively low among consumers. Half of the respondents were not sure of the health benefits associated with specific vegetables, except for carrots and spinach. Some respondents volunteered nutrient content or other information. There was no clear indication that consumers understand the specific health benefits conferred by consumption of vegetables. Nutrient and health benefit labelling therefore has the capacity to enhance knowledge of vegetable consumers. It is recommended that health benefit labelling be tailored to promote greater consumption of vegetables in those demographic groups where vegetable consumption was lower. The present study assists the Australian vegetable industry in helping consumers make more informed consumption choices. © 2016 Dietitians Association of Australia.

Evolution and cell-type specificity of human-specific genes preferentially expressed in progenitors of fetal neocortex.

PubMed

Florio, Marta; Heide, Michael; Pinson, Anneline; Brandl, Holger; Albert, Mareike; Winkler, Sylke; Wimberger, Pauline; Huttner, Wieland B; Hiller, Michael

2018-03-21

Understanding the molecular basis that underlies the expansion of the neocortex during primate, and notably human, evolution requires the identification of genes that are particularly active in the neural stem and progenitor cells of the developing neocortex. Here, we have used existing transcriptome datasets to carry out a comprehensive screen for protein-coding genes preferentially expressed in progenitors of fetal human neocortex. We show that 15 human-specific genes exhibit such expression, and many of them evolved distinct neural progenitor cell-type expression profiles and levels compared to their ancestral paralogs. Functional studies on one such gene, NOTCH2NL , demonstrate its ability to promote basal progenitor proliferation in mice. An additional 35 human genes with progenitor-enriched expression are shown to have orthologs only in primates. Our study provides a resource of genes that are promising candidates to exert specific, and novel, roles in neocortical development during primate, and notably human, evolution. © 2018, Florio et al.

Evolution and cell-type specificity of human-specific genes preferentially expressed in progenitors of fetal neocortex

PubMed Central

Pinson, Anneline; Brandl, Holger; Albert, Mareike; Winkler, Sylke; Wimberger, Pauline

2018-01-01

Understanding the molecular basis that underlies the expansion of the neocortex during primate, and notably human, evolution requires the identification of genes that are particularly active in the neural stem and progenitor cells of the developing neocortex. Here, we have used existing transcriptome datasets to carry out a comprehensive screen for protein-coding genes preferentially expressed in progenitors of fetal human neocortex. We show that 15 human-specific genes exhibit such expression, and many of them evolved distinct neural progenitor cell-type expression profiles and levels compared to their ancestral paralogs. Functional studies on one such gene, NOTCH2NL, demonstrate its ability to promote basal progenitor proliferation in mice. An additional 35 human genes with progenitor-enriched expression are shown to have orthologs only in primates. Our study provides a resource of genes that are promising candidates to exert specific, and novel, roles in neocortical development during primate, and notably human, evolution. PMID:29561261

An outbreak of Escherichia coli O157:H7 infection in southern Sweden associated with consumption of fermented sausage; aspects of sausage production that increase the risk of contamination

PubMed Central

SARTZ, L.; De JONG, B.; HJERTQVIST, M.; PLYM-FORSHELL, L.; ALSTERLUND, R.; LÖFDAHL, S.; OSTERMAN, B.; STÅHL, A.; ERIKSSON, E.; HANSSON, H.-B.; KARPMAN, D.

2008-01-01

SUMMARY A large outbreak of enterohaemorrhagic Escherichia coli (EHEC) infections occurred in southern Sweden during autumn 2002. A matched case-control study was performed and indicated an association between consumption of fermented sausage and EHEC infection (odds ratio 5·4, P<0·002). Pulsed-field gel electrophoresis analysis identified a strain of E. coli O157:H7 in clinical faecal isolates, which was identical to a strain isolated from sausage samples obtained from households of infected individuals. A combination of microbiological and epidemiological results established a link between sausage consumption and the outbreak in 30 out of a total of 39 investigated cases. Contaminated beef was suspected to be the source of infection. Delayed start of fermentation, lack of heat-treatment and a short curing period in cold temperature were identified as the main factors enabling EHEC survival. EHEC can survive throughout the entire production process of fermented sausage if curing conditions are inadequate. PMID:17445322

Molecular characterization of Aspergillus fumigatus isolated from raw cow milk in Argentina: Molecular typing of A. fumigatus from raw cow milk.

PubMed

Pena, Gabriela A; Alonso, Verónica; Manini, Marina Velasco; Pellegrino, M; Cavaglieri, Lilia R

2018-06-20

Aspergillus fumigatus, the major etiological agent of human and animal aspergillosis, is a gliotoxinogenic species into section Fumigati commonly found in contaminated animal environments. In dairy herds, exposed areas of lactating cows, as mammalian glandule, can be easily contaminated by them. This study was aimed to identify A. fumigatus sensu lato strains (identified based on morphology) isolated from raw cow milk at species level, by morphological and molecular techniques, and to estimate their genetic variability. Forty-five A. fumigatus strains showed similar RAPD profiles (generated with PELF and URP1F primers) to each other and to A. fumigatus sensu stricto reference strains; also, they were almost identical to clinical human and feed-borne A. fumigatus strains included in the assay, since their similarity coefficient ranged from 0.7 to 1.00. Therefore, all strains were characterized as belonging to A. fumigatus sensu stricto species. This result was supported by sequencing the benA gene of selected strains and by maximum parsimony analysis. In addition, RAPD fingerprinting demonstrated intra-specific genetic variability into the A. fumigatus sensu stricto cluster. The results found in this study strengthen the fact that A. fumigatus sensu stricto is the predominant species in the Aspergillus section Fumigati found in animal environments such as dairy herd environments, while other species such as A. novofumigatus, A. fumigatiaffinis, A. udagawae and A. lentulus may be rarely isolated. Since no differences between animal and human strains were observed they can become pathogenic also for farm handlers'. Moreover, the presence of A. fumigatus sensu stricto in raw cow milk is probably a very important risk factor since milk and its by-products are generally indented for human consumption, then gliotoxin could be transferred to them. Copyright © 2018. Published by Elsevier B.V.

Intergranular fracture of lithium fluoride-22 percent calcium fluoride hypereutectic salt at 800 K

NASA Technical Reports Server (NTRS)

Raj, Subramanium V.; Whittenberger, J. Daniel

1990-01-01

Substantial strain-hardening was noted during the initial stages of deformation in constant-velocity compression tests conducted on as-cast samples of the LiF-22 mol pct CaF2 hypereutectic salt at 800 K. The deformed specimens exhibited extensive grain-boundary cracking and cavitation, suggesting that such cracking, in conjunction with interfacial sliding, is important for cavity nucleation at grain boundaries and at the LiF-CaF2 interfaces. Cavity growth and interlinkage occur through the preferential failure of the weaker LiF phase.

Diatoms: a fossil fuel of the future.

PubMed

Levitan, Orly; Dinamarca, Jorge; Hochman, Gal; Falkowski, Paul G

2014-03-01

Long-term global climate change, caused by burning petroleum and other fossil fuels, has motivated an urgent need to develop renewable, carbon-neutral, economically viable alternatives to displace petroleum using existing infrastructure. Algal feedstocks are promising candidate replacements as a 'drop-in' fuel. Here, we focus on a specific algal taxon, diatoms, to become the fossil fuel of the future. We summarize past attempts to obtain suitable diatom strains, propose future directions for their genetic manipulation, and offer biotechnological pathways to improve yield. We calculate that the yields obtained by using diatoms as a production platform are theoretically sufficient to satisfy the total oil consumption of the US, using between 3 and 5% of its land area. Copyright © 2014 Elsevier Ltd. All rights reserved.

The Impact of Fe-Ti Oxide Concentration on the Structural Rigidity of the Lower Oceanic Crust, Atlantis Bank, Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Deans, J. R.; Winkler, D. A.

2017-12-01

Fe-Ti oxides are important components of oceanic core complexes (OCC) formed at slow-spreading ridges, since Fe-Ti oxide phases form throughout the crustal column and are weaker than silicate phases. This study investigated the predicted relationship between the presence and concentration of Fe-Ti oxides and the presence/intensity of crystal-plastic deformation in samples from Atlantis Bank, Southwest Indian Ridge (SWIR). Atlantis Bank is an OCC that formed through the exhumation of lower oceanic crust along a detachment shear zone/fault. OCCs form along slow-spreading ridges and are characterized by the complex interactions between magmatism and crustal extension, thus, making them more susceptible to crystal-plastic deformation at higher temperatures and for weaker phases like Fe-Ti oxides to preferentially partition strain. Atlantis Bank has been the focus of many scientific expeditions to various sites including; Ocean Drilling Program (ODP) Holes 735B and 1105A, and the International Oceanic Discovery Program (IODP) Hole U1473A. A total of 589 thin sections from all three holes were analyzed using the software package Fiji to calculate the Fe-Ti oxide concentration within the thin sections. The Fe-Ti oxide percentage was correlated with the crystal-plastic fabric (CPF) intensity, from 0-5 (no foliation - ultramylonite), for each thin section using the statistical software R. All three holes show a positive correlation between the abundance of Fe-Ti oxides and the CPF intensity. Specifically, 76.3% of samples with a concentration of 5% or more Fe-Ti oxides have a corresponding CPF intensity value of 2 or more (porphyroclastic foliation - ultramylonitic). The positive correlation may be explained by the Fe-Ti oxides preferentially partitioning strain, especially at temperatures below where dry plagioclase can recrystallize. This allows for a mechanism of continued slip along the shear zone or form new shear zones at amphibolite grade conditions while the lower crust is being exhumed. Additionally, IODP U1473A and ODP 1105A had similar correlation values of 0.11 (on a scale of -1 to 1), whereas ODP Hole 735B had double the correlation value of 0.24. Since ODP Hole 735B has older rocks than the other two holes, it may have recorded more deformation comparatively speaking.

Engineering of the glycerol decomposition pathway and cofactor regulation in an industrial yeast improves ethanol production.

PubMed

Zhang, Liang; Tang, Yan; Guo, Zhongpeng; Shi, Guiyang

2013-10-01

Glycerol is a major by-product of industrial ethanol production and its formation consumes up to 4 % of the sugar substrate. This study modified the glycerol decomposition pathway of an industrial strain of Saccharomyces cerevisiae to optimize the consumption of substrate and yield of ethanol. This study is the first to couple glycerol degradation with ethanol formation, to the best of our knowledge. The recombinant strain overexpressing GCY1 and DAK1, encoding glycerol dehydrogenase and dihydroxyacetone kinase, respectively, in glycerol degradation pathway, exhibited a moderate increase in ethanol yield (2.9 %) and decrease in glycerol yield (24.9 %) compared to the wild type with the initial glucose concentration of 15 % under anaerobic conditions. However, when the mhpF gene, encoding acetylating NAD⁺-dependent acetaldehyde dehydrogenase from Escherichia coli, was co-expressed in the aforementioned recombinant strain, a further increase in ethanol yield by 5.5 % and decrease in glycerol yield by 48 % were observed for the resultant recombinant strain GDMS1 when acetic acid was added into the medium prior to inoculation compared to the wild type. The process outlined in this study which enhances glycerol consumption and cofactor regulation in an industrial yeast is a promising metabolic engineering strategy to increase ethanol production by reducing the formation of glycerol.

Two consecutive nationwide outbreaks of Listeriosis in France, October 1999-February 2000.

PubMed

de Valk, H; Vaillant, V; Jacquet, C; Rocourt, J; Le Querrec, F; Stainer, F; Quelquejeu, N; Pierre, O; Pierre, V; Desenclos, J C; Goulet, V

2001-11-15

In France, listeriosis surveillance is based on mandatory notification of all culture-confirmed cases, with systematic typing of isolates and routine collection of the patient's food history. From October 1999 to March 2000, two outbreaks of listeriosis were detected through this enhanced surveillance system. In outbreak 1, analysis of the food histories of cases suggested brand X "rillettes," a pâté-like meat product, as the vehicle of infection, and the outbreak strain of Listeria monocytogenes was subsequently isolated from the incriminated rillettes. In outbreak 2, a case-control study showed that consumption of jellied pork tongue was strongly associated with infection with the outbreak strain (odds ratio = 75.5, 95% confidence interval: 4.7, 1,216.0). However, trace-back results did not permit incrimination of any particular manufacturer of jellied pork tongue, and the outbreak strain was not isolated from the incriminated food or from any production sites. Consumption of jellied pork tongue was discouraged on epidemiologic evidence alone. The consecutive occurrence of these two outbreaks confirms the epidemic potential of listeriosis, even in a context of decreasing incidence, and underlines the importance of timely case-reporting and systematic typing of human L. monocytogenes strains to allow early detection and separate investigation of different clusters.

Microaerobic conversion of xylose to ethanol in recombinant Saccharomyces cerevisiae SX6(MUT) expressing cofactor-balanced xylose metabolic enzymes and deficient in ALD6.

PubMed

Jo, Sung-Eun; Seong, Yeong-Je; Lee, Hyun-Soo; Lee, Soo Min; Kim, Soo-Jung; Park, Kyungmoon; Park, Yong-Cheol

2016-06-10

Xylose is a major monosugar in cellulosic biomass and should be utilized for cost-effective ethanol production. In this study, xylose-converting ability of recombinant Saccharomyces cerevisiae SX6(MUT) expressing NADH-preferring xylose reductase mutant (R276H) and other xylose-metabolic enzymes, and deficient in aldehyde dehydrogenase 6 (Ald6p) were characterized at microaerobic conditions using various sugar mixtures. The reduction of air supply from 0.5vvm to 0.1vvm increased specific ethanol production rate by 75% and did not affect specific xylose consumption rate. In batch fermentations using various concentrations of xylose (50-104g/L), higher xylose concentration enhanced xylose consumption rate and ethanol productivity but reduced ethanol yield, owing to the accumulation of xylitol and glycerol from xylose. SX6(MUT) consumed monosugars in pitch pine hydrolysates and produced 23.1g/L ethanol from 58.7g/L sugars with 0.39g/g ethanol yield, which was 14% higher than the host strain of S. cerevisiae D452-2 without the xylose assimilating enzymes. In conclusion, S. cerevisiae SX6(MUT) was characterized to possess high xylose-consuming ability in microaerobic conditions and a potential for ethanol production from cellulosic biomass. Copyright © 2016 Elsevier B.V. All rights reserved.

Utilization of concentrate after membrane filtration of sugar beet thin juice for ethanol production.

PubMed

Kawa-Rygielska, Joanna; Pietrzak, Witold; Regiec, Piotr; Stencel, Piotr

2013-04-01

The subject of this study was to investigate the feasibility of the concentrate obtained after membrane ultrafiltration of sugar beet thin juice for ethanol production and selection of fermentation conditions (yeast strain and media supplementation). Resulting concentrate was subjected to batch ethanol fermentation using two strains of Saccharomyces cerevisiae (Ethanol Red and Safdistill C-70). The effect of different forms of media supplementation (mineral salts: (NH4)2SO4, K2HPO4, MgCl2; urea+Mg3(PO4)2 and yeast extract) on the fermentation course was also studied. It was stated that sugar beet juice concentrate is suitable for ethanol production yielding, depending on the yeast strain, ca. 85-87 g L(-1) ethanol with ca. 82% practical yield and more than 95% of sugars consumption after 72 h of fermentation. Nutrients enrichment further increased ethanol yield. The best results were obtained for media supplemented with urea+Mg3(PO4)2 yielding 91.16-92.06 g L(-1) ethanol with practical yield ranging 84.78-85.62% and full sugars consumption. Copyright © 2013. Published by Elsevier Ltd.

Amplified effect of mild plastic anisotropy on residual stress and strain anisotropy

DOE PAGES

Prime, Michael B.

2017-07-01

Axisymmetric indentation of a geometrically axisymmetric disk produced residual stresses by non-uniform plastic deformation. The 2024 aluminum plate used to make the disk exhibited mild plastic anisotropy with about 10% lower strength in the transverse direction compared to the rolling and through-thickness directions. Residual stresses and strains in the disk were measured with neutron diffraction, slitting, the contour method, x-ray diffraction and hole drilling. Surprisingly, the residual-stress anisotropy measured in the disk was about 40%, the residual-strain anisotropy was an impressive 100%, and the residual stresses were higher in the weaker direction. The high residual stress anisotropy relative to themore » mild plastic anisotropy and the direction of the highest stress are explained by considering the mechanics of indentation: constraint on deformation provided by the material surrounding the indentation and preferential deformation in the most compliant direction for incremental deformation. By contrast, the much larger anisotropy in residual strain compared to that in residual stress is independent of the fabrication process and is instead explained by considering Hookean elasticity. For Poisson's ratio of 1/3, the relationship simplifies to the residual strain anisotropy equaling the square of the residual stress anisotropy, which matches the observed results (2 ≈ 1.4^2). Furthermore, a lesson from this study is that to accurately predict residual stresses and strains, one must be wary of seemingly reasonable simplifying assumptions such as neglecting mild plastic anisotropy.« less

Amplified effect of mild plastic anisotropy on residual stress and strain anisotropy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prime, Michael B.

Axisymmetric indentation of a geometrically axisymmetric disk produced residual stresses by non-uniform plastic deformation. The 2024 aluminum plate used to make the disk exhibited mild plastic anisotropy with about 10% lower strength in the transverse direction compared to the rolling and through-thickness directions. Residual stresses and strains in the disk were measured with neutron diffraction, slitting, the contour method, x-ray diffraction and hole drilling. Surprisingly, the residual-stress anisotropy measured in the disk was about 40%, the residual-strain anisotropy was an impressive 100%, and the residual stresses were higher in the weaker direction. The high residual stress anisotropy relative to themore » mild plastic anisotropy and the direction of the highest stress are explained by considering the mechanics of indentation: constraint on deformation provided by the material surrounding the indentation and preferential deformation in the most compliant direction for incremental deformation. By contrast, the much larger anisotropy in residual strain compared to that in residual stress is independent of the fabrication process and is instead explained by considering Hookean elasticity. For Poisson's ratio of 1/3, the relationship simplifies to the residual strain anisotropy equaling the square of the residual stress anisotropy, which matches the observed results (2 ≈ 1.4^2). Furthermore, a lesson from this study is that to accurately predict residual stresses and strains, one must be wary of seemingly reasonable simplifying assumptions such as neglecting mild plastic anisotropy.« less

Resource partitioning in relation to cohabitation of Lactobacillus species in the mouse forestomach

PubMed Central

Tannock, Gerald W; Wilson, Charlotte M; Loach, Diane; Cook, Gregory M; Eason, Jocelyn; O'Toole, Paul W; Holtrop, Grietje; Lawley, Blair

2012-01-01

Phylogenetic analysis of gut communities of vertebrates is advanced, but the relationships, especially at the trophic level, between commensals that share gut habitats of monogastric animals have not been investigated to any extent. Lactobacillus reuteri strain 100–23 and Lactobacillus johnsonii strain 100–33 cohabit in the forestomach of mice. According to the niche exclusion principle, this should not be possible because both strains can utilise the two main fermentable carbohydrates present in the stomach digesta: glucose and maltose. We show, based on gene transcription analysis, in vitro physiological assays, and in vivo experiments that the two strains can co-exist in the forestomach habitat because 100–23 grows more rapidly using maltose, whereas 100–33 preferentially utilises glucose. Mutation of the maltose phosphorylase gene (malA) of strain 100–23 prevented its growth on maltose-containing culture medium, and resulted in the numerical dominance of 100–33 in the forestomach. The fundamental niche of L. reuteri 100–23 in the mouse forestomach can be defined in terms of ‘glucose and maltose trophism'. However, its realised niche when L. johnsonii 100–33 is present is ‘maltose trophism'. Hence, nutritional adaptations provide niche differentiation that assists cohabitation by the two strains through resource partitioning in the mouse forestomach. This real life, trophic phenomenon conforms to a mathematical model based on in vitro bacterial doubling times, in vitro transport rates, and concentrations of maltose and glucose in mouse stomach digesta. PMID:22094343

Enhancement of amphotericin B activity against Candida albicans by superoxide radical.

PubMed

Okamoto, Yuichi; Aoki, Shigeji; Mataga, Izumi

2004-07-01

This study aimed to examine the involvement of oxidative damage in amphotericin B (AmB) activity against Candida albicans using the superoxide (O2-) generator paraquat (PQ). The effects of PQ on AmB activities against growth, viability, membrane permeability and respiration were examined in a wild-type parent strain (K) and a respiration-deficient mutant (KRD-19) since PQ-induced superoxide generation depends on respiration. In the parent strain, the minimal inhibitory concentration (MIC) of AmB, 0.25 microg/ml, tested with a liquid culture was lowered to 0.025 microg/ml by 1 mM PQ. Such a PQ-induced decrease in the MIC value of AmB was minimal in the mutant. Similar PQ-induced enhancement of AmB activity toward the parent strain was also observed with growth on an agar medium. In viability tests, when candidal cells were exposed to AmB (0.1 microg/ml) for I h, the lethality of AmB was enhanced by 1 mM PQ only in the parent strain. Exogenous superoxide dismutase and catalase failed to diminish the enhancing effect of PQ on the growth inhibitory activity of AmB in the parent strain, suggesting an interaction between superoxide and AmB in candidal cells. The enhancement of AmB activity by PQ, observed preferentially in the wild-type strain, can be explained by extensive superoxide generation depending on respiration. These results suggest that oxidative damage induced by superoxide is involved in AmB activity against C. albicans.

Development of strain-specific PCR primers for quantitative detection of Bacillus mesentericus strain TO-A in human feces.

PubMed

Sato, Naoki; Seo, Genichiro; Benno, Yoshimi

2014-01-01

Strain-specific polymerase chain reaction (PCR) primers for detection of Bacillus mesentericus strain TO-A (BM TO-A) were developed. The randomly amplified polymorphic DNA (RAPD) technique was used to produce potential strain-specific markers. A 991-bp RAPD marker found to be strain-specific was sequenced, and two primer pairs specific to BM TO-A were constructed based on this sequence. In addition, we explored a more specific DNA region using inverse PCR, and designed a strain-specific primer set for use in real-time quantitative PCR (qPCR). These primer pairs were tested against 25 Bacillus subtilis strains and were found to be strain-specific. After examination of the detection limit and linearity of detection of BM TO-A in feces, the qPCR method and strain-specific primers were used to quantify BM TO-A in the feces of healthy volunteers who had ingested 3×10(8) colony forming unit (CFU) of BM TO-A per day in tablets. During the administration period, BM TO-A was detected in the feces of all 24 subjects, and the average number of BM TO-A detected using the culture method and qPCR was about 10(4.8) and 10(5.8) cells per gram of feces, respectively. Using the qPCR method, BM TO-A was detected in the feces of half of the subjects 3 d after withdrawal, and was detected in the feces of only one subject 1 week after withdrawal. These results suggest that the qPCR method using BM TO-A strain-specific primers is useful for the quantitative detection of this strain in feces.

Distributed lags time series analysis versus linear correlation analysis (Pearson's r) in identifying the relationship between antipseudomonal antibiotic consumption and the susceptibility of Pseudomonas aeruginosa isolates in a single Intensive Care Unit of a tertiary hospital.

PubMed

Erdeljić, Viktorija; Francetić, Igor; Bošnjak, Zrinka; Budimir, Ana; Kalenić, Smilja; Bielen, Luka; Makar-Aušperger, Ksenija; Likić, Robert

2011-05-01

The relationship between antibiotic consumption and selection of resistant strains has been studied mainly by employing conventional statistical methods. A time delay in effect must be anticipated and this has rarely been taken into account in previous studies. Therefore, distributed lags time series analysis and simple linear correlation were compared in their ability to evaluate this relationship. Data on monthly antibiotic consumption for ciprofloxacin, piperacillin/tazobactam, carbapenems and cefepime as well as Pseudomonas aeruginosa susceptibility were retrospectively collected for the period April 2006 to July 2007. Using distributed lags analysis, a significant temporal relationship was identified between ciprofloxacin, meropenem and cefepime consumption and the resistance rates of P. aeruginosa isolates to these antibiotics. This effect was lagged for ciprofloxacin and cefepime [1 month (R=0.827, P=0.039) and 2 months (R=0.962, P=0.001), respectively] and was simultaneous for meropenem (lag 0, R=0.876, P=0.002). Furthermore, a significant concomitant effect of meropenem consumption on the appearance of multidrug-resistant P. aeruginosa strains (resistant to three or more representatives of classes of antibiotics) was identified (lag 0, R=0.992, P<0.001). This effect was not delayed and it was therefore identified both by distributed lags analysis and the Pearson's correlation coefficient. Correlation coefficient analysis was not able to identify relationships between antibiotic consumption and bacterial resistance when the effect was delayed. These results indicate that the use of diverse statistical methods can yield significantly different results, thus leading to the introduction of possibly inappropriate infection control measures. Copyright © 2010 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Molecular dynamic simulations of the intergranular films between alumina and silicon nitride crystal grains

NASA Astrophysics Data System (ADS)

Zhang, Shenghong

The intergranular films (IGFs) between the ceramics grains have very important effects on the structure and mechanical properties on the whole ceramics and have been studied for many decades. In the thesis, molecular dynamic (MD) computer simulations were applied to study the IGFs between the alumina and silicon nitride ceramic grains. Preferential adsorption of specific ions from the IGFs to the contacting surfaces of the alumina crystals was observed in the study of calcium-alumino-silicate glassy (CAS) IGFs formed between the combined basal and prism orientations of alpha-Al2O3 crystals. This segregation of specific ions to the interface enables formation of localized, ordered structures between the IGF and the crystals. However, the segregation behavior of the ions is anisotropic, depending on the orientation of the alpha-Al2O 3 crystals. Self-diffusion of calcium ions between these CAS IGFs was also carried out by MD simulations. The results show that the diffusion coefficients adjacent to the interfaces are smaller and the activation energies are much higher than those in the interior of the IGF and in bulk glasses. It was also suggested that Ca transport is mainly though the interior of the IGF and implies that diffusion would be significantly inhibited by sufficiently thin IGFs. The growth of the alumina ceramic grains was simulated in the contacting with IGFs containing high concentrations of aluminum ions. Five different compositions in the IGFs were studied. Results show preferential growth along the [1120] of the (1120) surface in comparison to growth along the [0001] direction on the (0001) surface for compositions near a Ca/Al ratio of 0.5. The simulations also show the mechanism by which Ca ions in the IGF inhibit growth on the basal surface. The simulations provide an atomistic view of attachment onto crystal surfaces, affecting grain growth in alumina. The dissolution of the alumina crystal grains in the silicate melts is another important issue in the application of alumina ceramics. The simulations results showed that alumina grains dissolved into the melts homogeneously at very high temperatures. The orientation of the crystals and the compositions of the melts only take effect at some intermediate temperatures, to make the alumina grains dissolution anisotropic. The fracture phenomena of the pure silica IGFs between the basal silicon nitride crystals were studied by applying the constant tensile strain on the simulated IGF system, as well as for the bulk silica glass for the comparison. The data indicated that the fracture was happened in the interior of the IGFs and the thickness of the IGFs has important effect on the fracture stress/strain relationships.

Preferential Association of Endophytic Bradyrhizobia with Different Rice Cultivars and Its Implications for Rice Endophyte Evolution

PubMed Central

Piromyou, Pongdet; Greetatorn, Teerana; Teamtisong, Kamonluck; Okubo, Takashi; Shinoda, Ryo; Nuntakij, Achara; Tittabutr, Panlada; Boonkerd, Nantakorn

2015-01-01

Plant colonization by bradyrhizobia is found not only in leguminous plants but also in nonleguminous species such as rice. To understand the evolution of the endophytic symbiosis of bradyrhizobia, the effect of the ecosystems of rice plantations on their associations was investigated. Samples were collected from various rice (Oryza sativa) tissues and crop rotational systems. The rice endophytic bradyrhizobia were isolated on the basis of oligotrophic properties, selective medium, and nodulation on siratro (Macroptilium atropurpureum). Six bradyrhizobial strains were obtained exclusively from rice grown in a crop rotational system. The isolates were separated into photosynthetic bradyrhizobia (PB) and nonphotosynthetic bradyrhizobia (non-PB). Thai bradyrhizobial strains promoted rice growth of Thai rice cultivars better than the Japanese bradyrhizobial strains. This implies that the rice cultivars possess characteristics that govern rice-bacterium associations. To examine whether leguminous plants in a rice plantation system support the persistence of rice endophytic bradyrhizobia, isolates were tested for legume nodulation. All PB strains formed symbioses with Aeschynomene indica and Aeschynomene evenia. On the other hand, non-PB strains were able to nodulate Aeschynomene americana, Vigna radiata, and M. atropurpureum but unable to nodulate either A. indica or A. evenia. Interestingly, the nodABC genes of all of these bradyrhizobial strains seem to exhibit low levels of similarity to those of Bradyrhizobium diazoefficiens USDA110 and Bradyrhizobium sp. strain ORS285. From these results, we discuss the evolution of the plant-bradyrhizobium association, including nonlegumes, in terms of photosynthetic lifestyle and nod-independent interactions. PMID:25710371

Mechanism of fast lattice diffusion of hydrogen in palladium: Interplay of quantum fluctuations and lattice strain

NASA Astrophysics Data System (ADS)

Kimizuka, Hajime; Ogata, Shigenobu; Shiga, Motoyuki

2018-01-01

Understanding the underlying mechanism of the nanostructure-mediated high diffusivity of H in Pd is of recent scientific interest and also crucial for industrial applications. Here, we present a decisive scenario explaining the emergence of the fast lattice-diffusion mode of interstitial H in face-centered cubic Pd, based on the quantum mechanical natures of both electrons and nuclei under finite strains. Ab initio path-integral molecular dynamics was applied to predict the temperature- and strain-dependent free energy profiles for H migration in Pd over a temperature range of 150-600 K and under hydrostatic tensile strains of 0.0%-2.4%; such strain conditions are likely to occur in real systems, especially around the elastic fields induced by nanostructured defects. The simulated results revealed that, for preferential H location at octahedral sites, as in unstrained Pd, the activation barrier for H migration (Q ) was drastically increased with decreasing temperature owing to nuclear quantum effects. In contrast, as tetrahedral sites increased in stability with lattice expansion, nuclear quantum effects became less prominent and ceased impeding H migration. This implies that the nature of the diffusion mechanism gradually changes from quantum- to classical-like as the strain is increased. For H atoms in Pd at the hydrostatic strain of ˜2.4 % , we determined that the mechanism promoted fast lattice diffusion (Q =0.11 eV) of approximately 20 times the rate of conventional H diffusion (Q =0.23 eV) in unstrained Pd at a room temperature of 300 K.

Pandemic Vibrio parahaemolyticus O3:K6 on the American continent

PubMed Central

Velazquez-Roman, Jorge; León-Sicairos, Nidia; de Jesus Hernández-Díaz, Lucio; Canizalez-Roman, Adrian

2014-01-01

Vibrio parahaemolyticus is one of the most important seafood-borne bacterial in recent years and is the leading causal agent of human acute gastroenteritis, primarily following the consumption of raw, undercooked or mishandled marine products. Until 1996, infections caused by V. parahaemolyticus were generally associated with diverse serovars. However, in February 1996, a unique serovar (O3:K6) of V. parahaemolyticus with specific genetic markers (tdh, toxRS/New and/or orf8) appeared abruptly in Kolkata, India. In subsequent years, O3:K6 isolates similar to those isolated in Kolkata have been reported from food borne outbreaks in Southeast Asia, as well as in the Atlantic and Gulf coasts of the United States (U.S). More recently, there have been reports in Europe, Africa and Central and South America. Specifically, in the American continent, some countries have reported cases of gastroenteritis due to the pandemic O3:K6 strain and its serovariants; the pandemic strain was first detected in Peru (1996, >100 cases), subsequently spreading to Chile in 1998 (>16,804 human cases), to the U.S. in 1998 (>700 cases), to Brazil in 2001 (>18 cases) and to Mexico in 2004 (>1200 cases). The arrival of the pandemic clone on the American continent may have resulted in a significant shift on the epidemic dynamics of V. parahaemolyticus. However, although O3:K6 is the predominant serovar of the recognized clinical strains in some countries in the Americas, a decrease in clinical cases caused by O3:K6 and an increase in cases associated with a new serotype (O3:K59, Chile) have been recently reported. The emergence and worldwide dissemination of O3:K6 and other pandemic strains since 1996 have come to represent a threat to public health and should concern health authorities. This review focuses on the presence, distribution and virulence factors of the V. parahaemolyticus O3:K6 pandemic clone and its serovariants in clinical and environmental strains on the American continent. PMID:24427744

FLO1 is a variable green beard gene that drives biofilm-like cooperation in budding yeast

PubMed Central

Smukalla, Scott; Caldara, Marina; Pochet, Nathalie; Beauvais, Anne; Guadagnini, Stephanie; Yan, Chen; Vinces, Marcelo D.; Jansen, An; Prevost, Marie Christine; Latgé, Jean-Paul; Fink, Gerald R.; Foster, Kevin R.; Verstrepen, Kevin J.

2008-01-01

Summary The budding yeast, Saccharomyces cerevisiae, has emerged as an archetype of eukaryotic cell biology. Here we show that S. cerevisiae is also a model for the evolution of cooperative behavior by revisiting flocculation, a self-adherence phenotype lacking in most laboratory strains. Expression of the gene FLO1 in the laboratory strain S288C restores flocculation, an altered physiological state, reminiscent of bacterial biofilms. Flocculation protects the FLO1-expressing cells from multiple stresses, including antimicrobials and ethanol. Furthermore, FLO1+ cells avoid exploitation by non-expressing flo1 cells by self/non-self recognition: FLO1+ cells preferentially stick to one another, regardless of genetic relatedness across the rest of the genome. Flocculation, therefore, is driven by one of a few known “green beard genes”, which direct cooperation towards other carriers of the same gene. Moreover, FLO1 is highly variable among strains both in expression and in sequence, suggesting that flocculation in S. cerevisiae is a dynamic, rapidly-evolving social trait. PMID:19013280

Design, synthesis and DNA-binding study of some novel morpholine linked thiazolidinone derivatives

NASA Astrophysics Data System (ADS)

War, Javeed Ahmad; Srivastava, Santosh Kumar; Srivastava, Savitri Devi

2017-02-01

The emergence of multiple drug resistance amongst bacterial strains resulted in many clinical drugs to be ineffective. Being vulnerable to bacterial infections any lack in the development of new antimicrobial drugs could pose a serious threat to public health. Here we report design and synthesis of a novel class of morpholine linked thiazolidinone hybrid molecules. The compounds were characterized by FT-IR, NMR and HRMS techniques. Susceptibility tests showed that most of the synthesized molecules were highly active against multiple bacterial strains. Compound 3f displayed MIC values which were better than the standard drug for most of the tested strains. DNA being a well defined target for many antimicrobial drugs was probed as possible target for these synthetic molecules. DNA-binding study of 3f with sm-DNA was probed through UV-vis absorption, fluorescence quenching, gel electrophoresis and molecular docking techniques. The studies revealed that compound 3f has strong affinity towards DNA and binds at the minor groove. The docking studies revealed that the compound 3f shows preferential binding towards A/T residues.

Design, synthesis and DNA-binding study of some novel morpholine linked thiazolidinone derivatives.

PubMed

War, Javeed Ahmad; Srivastava, Santosh Kumar; Srivastava, Savitri Devi

2017-02-15

The emergence of multiple drug resistance amongst bacterial strains resulted in many clinical drugs to be ineffective. Being vulnerable to bacterial infections any lack in the development of new antimicrobial drugs could pose a serious threat to public health. Here we report design and synthesis of a novel class of morpholine linked thiazolidinone hybrid molecules. The compounds were characterized by FT-IR, NMR and HRMS techniques. Susceptibility tests showed that most of the synthesized molecules were highly active against multiple bacterial strains. Compound 3f displayed MIC values which were better than the standard drug for most of the tested strains. DNA being a well defined target for many antimicrobial drugs was probed as possible target for these synthetic molecules. DNA-binding study of 3f with sm-DNA was probed through UV-vis absorption, fluorescence quenching, gel electrophoresis and molecular docking techniques. The studies revealed that compound 3f has strong affinity towards DNA and binds at the minor groove. The docking studies revealed that the compound 3f shows preferential binding towards A/T residues. Copyright © 2016 Elsevier B.V. All rights reserved.

Misfit strain-temperature phase diagrams and domain stability of asymmetric ferroelectric capacitors: Thermodynamic calculation and phase-field simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, W. J.; Zheng, Yue, E-mail: zhengy35@mail.sysu.edu.cn; Wu, C. M.

Thermodynamic calculation and phase-field simulation have been conducted to investigate the misfit strain-temperature phase diagrams, dielectric property, and domain stability of asymmetric ferroelectric capacitors (FCs), with considering the effects of dissimilar screening properties and work function steps at the two interfaces. The distinct features of asymmetric FCs from their symmetric counterparts have been revealed and discussed. Polar states with nonzero out-of-plane polarization in parallel with the built-in field are found preferential to form in asymmetric FCs. Meanwhile, the built-in field breaks the degeneracy of states with out-of-plane polarization in anti-directions. This leads to the necessity of redefining phases according tomore » the bistability of out-of-plane polarization. Moreover, the phase stability as well as the dielectric behavior can be significantly controlled by the properties of electrodes, misfit strain, and temperature. The phase-field simulation result also shows that polydomain instability would happen in asymmetric FCs as the equivalence of domain stability in anti-directions is destroyed.« less

Molecular cloning and characterization of a cDNA encoding a novel apoplastic protein preferentially expressed in a shikonin-producing callus strain of Lithospermum erythrorhizon.

PubMed

Yamamura, Yoshimi; Sahin, F Pinar; Nagatsu, Akito; Mizukami, Hajime

2003-04-01

A cDNA (LEPS-2) encoding a novel cell wall protein was cloned from shikonin-producing callus tissues of Lithospermum erythrorhizon by differential display between a shikonin-producing culture strain and a non-producing strain. The LEPS-2 cDNA encoded a polypeptide of 184 amino acids. The deduced amino acid sequence exhibited no significant homology with known proteins. Expression of LEPS-2 gene as well as accumulation of LEPS-2 protein was highly correlated with shikonin production in L. erythrorhizon cells in culture. In the intact plant, expression of LEPS-2 was detected only in the roots where shikonin pigments accumulated. Cell fractionation experiments and immunocytochemical analysis showed that the protein was localized in the apoplast fraction of the cell walls. The shikonin pigments were also stored on the cell walls as oil droplets. These results indicate that expression of the LEPS-2 is closely linked with shikonin biosynthesis and the LEPS-2 protein may be involved in the intra-cell wall trapping of shikonin pigments.

Measles virus C protein suppresses gamma-activated factor formation and virus-induced cell growth arrest

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yokota, Shin-ichi; Okabayashi, Tamaki; Fujii, Nobuhiro, E-mail: fujii@sapmed.ac.j

2011-05-25

Measles virus (MeV) produces two accessory proteins, V and C, from the P gene. These accessory proteins have been reported to contribute to efficient virus proliferation through the modulation of host cell events. Our previous paper described that Vero cell-adapted strains of MeV led host cells to growth arrest through the upregulation of interferon regulatory factor 1 (IRF-1), and wild strains did not. In the present study, we found that C protein expression levels varied among MeV strains in infected SiHa cells. C protein levels were inversely correlated with IRF-1 expression levels and with cell growth arrest. Forced expression ofmore » C protein released cells from growth arrest. C-deficient recombinant virus efficiently upregulated IRF-1 and caused growth arrest more efficiently than the wild-type virus. C protein preferentially bound to phosphorylated STAT1 and suppressed STAT1 dimer formation. We conclude that MeV C protein suppresses IFN-{gamma} signaling pathway via inhibition of phosphorylated STAT1 dimerization.« less

Repeated batch cultivation of the hydrocarbon-degrading, micro-algal strain Prototheca zopfii RND16 immobilized in polyurethane foam.

PubMed

Ueno, Ryohei; Wada, Shun; Urano, Naoto

2008-01-01

This study reports on the stability of the cells of a heterotrophic green micro-algal strain Prototheca zopfii RND16 immobilized in polyurethane foam (PUF) cubes during degradation of mixed hydrocarbon substrate, which was composed of n-alkanes and polycyclic aromatic hydrocarbons (PAHs), in 5 successive cycles of repeated batch cultivation at 30 degrees C. Both RND16 cells and mixed hydrocarbon substrate components had been entrapped in PUF cubes through cultivation. PUF-immobilized RND16 degraded n-alkanes almost completely, whereas the strain hardly degraded PAHs in PUFs, rather they accumulated in the matrices. It is noteworthy that this result is strikingly different from that of the free-living cell culture, where RND16 reduced concentrations of both n-alkanes and PAHs. However, PAHs accumulation in the PUFs did not impair the performance of the immobilized alga to utilize n-alkanes. These results suggest that the PUFs harboring RND16 cells could be used repeatedly for selective retrieval of PAHs from oil-polluted waters after preferential biodegradation of n-alkanes by algae.

Rodent model choice has major impact on variability of standard preclinical readouts associated with diabetes and obesity research

PubMed Central

Jensen, Victoria S; Porsgaard, Trine; Lykkesfeldt, Jens; Hvid, Henning

2016-01-01

Laboratory rodents are available as either genetically defined inbred strains or genetically undefined outbred stocks. As outbred rodents are generally thought to display a higher level of phenotypic variation compared to inbred strains, it has been argued that experimental studies should preferentially be performed by using inbred rodents. However, very few studies with adequate sample sizes have in fact compared phenotypic variation between inbred strains and outbred stocks of rodents and moreover, these studies have not reached consistent conclusions. The aim of the present study was to compare the phenotypic variation in commonly used experimental readouts within obesity and diabetes research, for four of the most frequently used mouse strains: inbred C57BL/6 and BALB/c and outbred NMRI and CD-1 mice. The variation for all readouts was examined by calculating the coefficient of variation (CV), i.e., the relative variation, including a 95% confidence interval for the CV. We observed that for the majority of the selected readouts, inbred and outbred mice showed comparable phenotypic variation. The observed variation appeared highly influenced by strain choice and type of readout, which suggests that these collectively would serve as more predictive of the phenotypic variation than the more general classification of mice as inbred or outbred based on genetic heterogeneity. PMID:27648148

Bioleaching of rare earth elements from monazite sand.

PubMed

Brisson, Vanessa L; Zhuang, Wei-Qin; Alvarez-Cohen, Lisa

2016-02-01

Three fungal strains were found to be capable of bioleaching rare earth elements from monazite, a rare earth phosphate mineral, utilizing the monazite as a phosphate source and releasing rare earth cations into solution. These organisms include one known phosphate solubilizing fungus, Aspergillus niger ATCC 1015, as well as two newly isolated fungi: an Aspergillus terreus strain ML3-1 and a Paecilomyces spp. strain WE3-F. Although monazite also contains the radioactive element Thorium, bioleaching by these fungi preferentially solubilized rare earth elements over Thorium, leaving the Thorium in the solid residual. Adjustments in growth media composition improved bioleaching performance measured as rare earth release. Cell-free spent medium generated during growth of A. terreus strain ML3-1 and Paecilomyces spp. strain WE3-F in the presence of monazite leached rare earths to concentrations 1.7-3.8 times those of HCl solutions of comparable pH, indicating that compounds exogenously released by these organisms contribute substantially to leaching. Organic acids released by the organisms included acetic, citric, gluconic, itaconic, oxalic, and succinic acids. Abiotic leaching with laboratory prepared solutions of these acids was not as effective as bioleaching or leaching with cell-free spent medium at releasing rare earths from monazite, indicating that compounds other than the identified organic acids contribute to leaching performance. © 2015 Wiley Periodicals, Inc.

Tetrahedron deformation and alignment of perceived vorticity and strain in a turbulent flow

NASA Astrophysics Data System (ADS)

Pumir, Alain; Bodenschatz, Eberhard; Xu, Haitao

2013-03-01

We describe the structure and dynamics of turbulence by the scale-dependent perceived velocity gradient tensor as supported by following four tracers, i.e., fluid particles, that initially form a regular tetrahedron. We report results from experiments in a von Kármán swirling water flow and from numerical simulations of the incompressible Navier-Stokes equation. We analyze the statistics and the dynamics of the perceived rate of strain tensor and vorticity for initially regular tetrahedron of size r0 from the dissipative to the integral scale. Just as for the true velocity gradient, at any instant, the perceived vorticity is also preferentially aligned with the intermediate eigenvector of the perceived rate of strain. However, in the perceived rate of strain eigenframe fixed at a given time t = 0, the perceived vorticity evolves in time such as to align with the strongest eigendirection at t = 0. This also applies to the true velocity gradient. The experimental data at the higher Reynolds number suggests the existence of a self-similar regime in the inertial range. In particular, the dynamics of alignment of the perceived vorticity and strain can be rescaled by t0, the turbulence time scale of the flow when the scale r0 is in the inertial range. For smaller Reynolds numbers we found the dynamics to be scale dependent.

Effects of Bacillus thuringiensis strains virulent to Varroa destructor on larvae and adults of Apis mellifera.

PubMed

Alquisira-Ramírez, Eva Vianey; Peña-Chora, Guadalupe; Hernández-Velázquez, Víctor Manuel; Alvear-García, Andrés; Arenas-Sosa, Iván; Suarez-Rodríguez, Ramón

2017-08-01

The sublethal effects of two strains of Bacillus thuringiensis, which were virulent in vitro to Varroa destructor, were measured on Apis mellifera. The effects of five concentrations of total protein (1, 5, 25, 50 and 100μg/mL) from the EA3 and EA26.1 strains on larval and adult honey bees were evaluated for two and seven days under laboratory conditions. Based on the concentrations evaluated, total protein from the two strains did not affect the development of larvae, the syrup consumption, locomotor activity or proboscis extension response of adults. These same parameters were also tested for the effects of three concentrations (1, 10 and 15μg/kg) of cypermethrin as a positive control. Although no significant differences were observed after two days of treatment with cypermethrin, a dose-response relationship in syrup consumption and locomotor activity was observed. A significant reduction in the proboscis extension response of the bees treated with cypermethrin was also observed. Therefore, in contrast to cypermethrin, our results indicate that the EA3 and EA26.1 strains of B. thuringiensis can be used in beehives to control V. destructor and reduce the negative effects of this mite on colonies without adverse effects on the larvae and adults of A. mellifera. Additionally, the overuse of synthetic miticides, which produce both lethal and sublethal effects on bees, can be reduced. Copyright © 2017 Elsevier Inc. All rights reserved.

Flocculation causes inhibitor tolerance in Saccharomyces cerevisiae for second-generation bioethanol production.

PubMed

Westman, Johan O; Mapelli, Valeria; Taherzadeh, Mohammad J; Franzén, Carl Johan

2014-11-01

Yeast has long been considered the microorganism of choice for second-generation bioethanol production due to its fermentative capacity and ethanol tolerance. However, tolerance toward inhibitors derived from lignocellulosic materials is still an issue. Flocculating yeast strains often perform relatively well in inhibitory media, but inhibitor tolerance has never been clearly linked to the actual flocculation ability per se. In this study, variants of the flocculation gene FLO1 were transformed into the genome of the nonflocculating laboratory yeast strain Saccharomyces cerevisiae CEN.PK 113-7D. Three mutants with distinct differences in flocculation properties were isolated and characterized. The degree of flocculation and hydrophobicity of the cells were correlated to the length of the gene variant. The effect of different strength of flocculation on the fermentation performance of the strains was studied in defined medium with or without fermentation inhibitors, as well as in media based on dilute acid spruce hydrolysate. Strong flocculation aided against the readily convertible inhibitor furfural but not against less convertible inhibitors such as carboxylic acids. During fermentation of dilute acid spruce hydrolysate, the most strongly flocculating mutant with dense cell flocs showed significantly faster sugar consumption. The modified strain with the weakest flocculation showed a hexose consumption profile similar to the untransformed strain. These findings may explain why flocculation has evolved as a stress response and can find application in fermentation-based biorefinery processes on lignocellulosic raw materials. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Outbreak of CTX-M-15-Producing Enterotoxigenic Escherichia coli O159:H20 in the Republic of Korea in 2016.

PubMed

Kim, Jin Seok; Park, Jungsun; Shin, Eunkyung; Kim, Soojin; Oh, Sung Suck; Yang, Hyo-Jin; Kim, Dae-Won; Oh, Kyung-Hwan; Kim, Yonghoon; Kim, Min; Kwon, Mun Ju; Na, Kyoungin; Lee, Jin; Cho, En-Hi; Kang, Byung-Hak; Kwak, Hyo-Sun; Seong, Won Keun; Kim, Junyoung

2017-09-01

We investigated an outbreak of enterotoxigenic Escherichia coli (ETEC) O159:H20 associated with the consumption of a tossed-noodle dish in a high school in 2016. Thirty-three ETEC strains isolated from clinical and food samples were genetically indistinguishable. The outbreak strains were resistant to third-generation cephalosporins and harbored a bla CTX-M-15 gene on a 97-kb self-transferable IncK plasmid. This is the first outbreak caused by CTX-M-15-producing ETEC strains. Copyright © 2017 American Society for Microbiology.

Mercaptosuccinate Dioxygenase, a Cysteine Dioxygenase Homologue, from Variovorax paradoxus Strain B4 Is the Key Enzyme of Mercaptosuccinate Degradation

PubMed Central

Brandt, Ulrike; Schürmann, Marc; Steinbüchel, Alexander

2014-01-01

The versatile thiol mercaptosuccinate has a wide range of applications, e.g. in quantum dot research or in bioimaging. Its metabolism is investigated in Variovorax paradoxus strain B4, which can utilize this compound as the sole source of carbon and sulfur. Proteomic studies of strain B4 resulted in the identification of a putative mercaptosuccinate dioxygenase, a cysteine dioxygenase homologue, possibly representing the key enzyme in the degradation of mercaptosuccinate. Therefore, the putative mercaptosuccinate dioxygenase was heterologously expressed, purified, and characterized in this study. The results clearly demonstrated that the enzyme utilizes mercaptosuccinate with concomitant consumption of oxygen. Thus, the enzyme is designated as mercaptosuccinate dioxygenase. Succinate and sulfite were verified as the final reaction products. The enzyme showed an apparent Km of 0.4 mm, and a specific activity (Vmax) of 20.0 μmol min−1 mg−1 corresponding to a kcat of 7.7 s−1. Furthermore, the enzyme was highly specific for mercaptosuccinate, no activity was observed with cysteine, dithiothreitol, 2-mercaptoethanol, and 3-mercaptopropionate. These structurally related thiols did not have an inhibitory effect either. Fe(II) could clearly be identified as metal cofactor of the mercaptosuccinate dioxygenase with a content of 0.6 mol of Fe(II)/mol of enzyme. The recently proposed hypothesis for the degradation pathway of mercaptosuccinate based on proteome analyses could be strengthened in the present study. (i) Mercaptosuccinate is first converted to sulfinosuccinate by this mercaptosuccinate dioxygenase; (ii) sulfinosuccinate is spontaneously desulfinated to succinate and sulfite; and (iii) whereas succinate enters the central metabolism, sulfite is detoxified by the previously identified putative molybdopterin oxidoreductase. PMID:25228698

Comparative genomics of Lactobacillus

PubMed Central

Kant, Ravi; Blom, Jochen; Palva, Airi; Siezen, Roland J.; de Vos, Willem M.

2011-01-01

Summary The genus Lactobacillus includes a diverse group of bacteria consisting of many species that are associated with fermentations of plants, meat or milk. In addition, various lactobacilli are natural inhabitants of the intestinal tract of humans and other animals. Finally, several Lactobacillus strains are marketed as probiotics as their consumption can confer a health benefit to host. Presently, 154 Lactobacillus species are known and a growing fraction of these are subject to draft genome sequencing. However, complete genome sequences are needed to provide a platform for detailed genomic comparisons. Therefore, we selected a total of 20 genomes of various Lactobacillus strains for which complete genomic sequences have been reported. These genomes had sizes varying from 1.8 to 3.3 Mb and other characteristic features, such as G+C content that ranged from 33% to 51%. The Lactobacillus pan genome was found to consist of approximately 14 000 protein‐encoding genes while all 20 genomes shared a total of 383 sets of orthologous genes that defined the Lactobacillus core genome (LCG). Based on advanced phylogeny of the proteins encoded by this LCG, we grouped the 20 strains into three main groups and defined core group genes present in all genomes of a single group, signature group genes shared in all genomes of one group but absent in all other Lactobacillus genomes, and Group‐specific ORFans present in core group genes of one group and absent in all other complete genomes. The latter are of specific value in defining the different groups of genomes. The study provides a platform for present individual comparisons as well as future analysis of new Lactobacillus genomes. PMID:21375712

Investigation of Bucket Wheel Excavator Lattice Structure Internal Stress in Harsh Environment through a Remote Measurement System

NASA Astrophysics Data System (ADS)

Risteiu, M.; Dobra, R.; Andras, I.; Roventa, M.; Lorincz, A.

2017-06-01

The paper shows the results of a lab model for strain gauges based measuring system for multiple measuring heads of the mechanical stress in lattice structures of the bucket wheel excavator for open pit mines-harsh environment. The system is designed around a microcontroller system. Because of specific working conditions, the measuring system sends data to a processing system (a PC with Matlab software), we have implemented a secure communication solution based on ISM standard, by using NRF24L01 module. The transceiver contains a fully integrated frequency synthesizer based on crystal oscillator, and a Enhanced ShockBurst™ protocol engine. The proposed solution has a current consumption around 9.0 mA at an output power of -6dBm and 12.3mA in RX mode. Built-in Power Down and Standby modes makes power saving easily realizable for our solution battery powered. The stress from structures is taken by specific strain gauges adapted to low frequency vibrations. We are using a precision 24-bit analog-to-digital converter (ADC) designed for weigh scales and industrial control applications to interface directly with a bridge sensor-instrumentation device, with low drift voltage, low noise, common mode rejection signal, frequency and temperature stability. As backup implementation for measurements a high speed storage implementation is used.

Interspecies Interactions and Potential Influenza A Virus Risk in Small Swine Farms in Peru

DTIC Science & Technology

2012-03-15

or ducks was observed in 36% of all farms. Human-avian interactions were less frequent overall. Use of adequate biosecurity and hygiene practices by...Wild, aquatic birds—especially ducks and geese—are widely recognized to be reservoirs of IAVs [1]. Numerous avian influenza strains have been...combination of avian and human influenza strains [22,23]. Increased human consumption of meat , more efficient animal husbandry practices and the

Identification and characterization of three Penicillium chrysogenum α-l-arabinofuranosidases (PcABF43B, PcABF51C, and AFQ1) with different specificities toward arabino-oligosaccharides.

PubMed

Shinozaki, Ayaka; Hosokawa, Sachiko; Nakazawa, Masami; Ueda, Mitsuhiro; Sakamoto, Tatsuji

2015-06-01

We previously described four α-l-arabinofuranosidases (ABFs) secreted by Penicillium chrysogenum 31B. Here, we cloned the fifth and sixth genes (Pcabf43B and Pcabf51C) encoding the ABFs PcABF43B and PcABF51C in this strain and overexpressed these genes in Escherichia coli. The deduced amino acid sequences of PcABF43B and PcABF51C were highly similar to putative ABFs belonging to glycoside hydrolase families 43 and 51, respectively. Semiquantitative reverse transcription polymerase chain reaction indicated that both genes were induced by arabinose, arabinitol, arabinan, and arabinoxylan; however, the Pcabf51C gene was constitutively expressed at low levels in P. chrysogenum 31B. PcABF43B had optimal activity at 20°C and pH 5-6, indicating that this enzyme was psychrophilic and had the lowest optimal temperature reported for ABFs. PcABF51C had optimal activity at 45°C and pH 6-7. Both recombinant enzymes showed high activity on arabino-oligosaccharides, but little activity on arabinose-containing polysaccharides, such as l-arabinan. Next, we compared the substrate specificities of PcABF43B, PcABF51C, and AFQ1, a P. chrysogenum ABF that preferentially degraded oligosaccharides over polysaccharides. PcABF43B was found to preferentially hydrolyze (1→3)-linkages in branched arabino-oligosaccharides and released only a small amount of arabinose from linear α-1,5-arabino-oligosaccharides. In contrast, AFQ1 and PcABF51C showed higher activities on linear arabino-oligosaccharides than on branched arabino-oligosaccharides. AFQ1 showed high catalytic efficiencies for α-1,5-l-arabinofuranobiose (α-1,5-Ara2) and α-1,5-l-arabinofuranotriose (α-1,5-Ara3) at the same level. In contrast, intracellular PcABF51C showed much higher catalytic efficiency for α-1,5-Ara2 than for α-1,5-Ara3. Copyright © 2015 Elsevier Inc. All rights reserved.

Tuning optical properties of CdTe films with nanocolumnar morphology grown using OAD for improving light absorption in thin-film solar cells

NASA Astrophysics Data System (ADS)

Daza, L. G.; Canché-Caballero, V.; Chan y Díaz, E.; Castro-Rodríguez, R.; Iribarren, A.

2017-11-01

CdTe films with transversal morphology in form of tilted nanocolumns were obtained by sublimation method using a rotating vapour source combined with the oblique angle deposition technique. The tilt angles of the nanocolumnar structures increases as the substrate inclination also increase. CdTe films exhibited cubic zinc blend lattice under compressive strain. Morphological and x-ray diffractometry analysis indicated that the nanocolumns are grains stacked in the nanocolumn preferential growth direction, except for the films with non-inclined substrate. We found an interesting dependence of band gap energy and the refractive index as functions of the microstrain distribution due to the nanocolumn tilt in the films from 0° to about 25°. These facts evidence the possibility of carried out film strain engineering for optimizing optoelectronics devices as we propose for the case of thin-film solar cells.

Thinking about Bacillus subtilis as a multicellular organism.

PubMed

Aguilar, Claudio; Vlamakis, Hera; Losick, Richard; Kolter, Roberto

2007-12-01

Initial attempts to use colony morphogenesis as a tool to investigate bacterial multicellularity were limited by the fact that laboratory strains often have lost many of their developmental properties. Recent advances in elucidating the molecular mechanisms underlying colony morphogenesis have been made possible through the use of undomesticated strains. In particular, Bacillus subtilis has proven to be a remarkable model system to study colony morphogenesis because of its well-characterized developmental features. Genetic screens that analyze mutants defective in colony morphology have led to the discovery of an intricate regulatory network that controls the production of an extracellular matrix. This matrix is essential for the development of complex colony architecture characterized by aerial projections that serve as preferential sites for sporulation. While much progress has been made, the challenge for future studies will be to determine the underlying mechanisms that regulate development such that differentiation occurs in a spatially and temporally organized manner.

Pressure-strain energy redistribution in compressible turbulence: return-to-isotropy versus kinetic-potential energy equipartition

NASA Astrophysics Data System (ADS)

Lee, Kurnchul; Venugopal, Vishnu; Girimaji, Sharath S.

2016-08-01

Return-to-isotropy and kinetic-potential energy equipartition are two fundamental pressure-moderated energy redistributive processes in anisotropic compressible turbulence. Pressure-strain correlation tensor redistributes energy among various Reynolds stress components and pressure-dilatation is responsible for energy reallocation between dilatational kinetic and potential energies. The competition and interplay between these pressure-based processes are investigated in this study. Direct numerical simulations (DNS) of low turbulent Mach number dilatational turbulence are performed employing the hybrid thermal Lattice Boltzman method (HTLBM). It is found that a tendency towards equipartition precedes proclivity for isotropization. An evolution towards equipartition has a collateral but critical effect on return-to-isotropy. The preferential transfer of energy from strong (rather than weak) Reynolds stress components to potential energy accelerates the isotropization of dilatational fluctuations. Understanding of these pressure-based redistributive processes is critical for developing insight into the character of compressible turbulence.

Relation between alternating open/closed-conduit conditions and deformation patterns: An example from the Somma-Vesuvius volcano (southern Italy)

NASA Astrophysics Data System (ADS)

Tramparulo, F. D. A.; Vitale, S.; Isaia, R.; Tadini, A.; Bisson, M.; Prinzi, E. P.

2018-07-01

We present the results of a meso-scale systematic structural analysis of fractures, faults and dykes exposed at the Somma-Vesuvius volcano (southern Italy). Observed fractures include: (i) radial and tangential (with respect the caldera axis), sub-metric to metric joints associated with the edifice load and volcano-tectonic activity (i.e. inflation, deflation and caldera collapse stages) and (ii) decameter-scale fractures related to volcano flank instabilities. For the Somma-Vesuvius volcano, preexisting radial joints were commonly reactivated as transfer faults during the caldera formation, allowing different blocks to move toward the center of the collapsing area. Dykes occur with different geometries, including en-echelon structures bounding structural depressions. The orientation analysis of all structures indicates that they are preferentially oriented. Furthermore, we provide a morphological lineament analysis using high-resolution Digital Terrain Models of Somma-Vesuvius. Azimuth and spatial distribution of dykes and morphological lineaments were analyzed for comparison with the old Somma Crater and Gran Cono axes, respectively. Results highlight the overprinting of radial and clustered strain patterns recorded in different volcano-tectonic evolution stages. We suggest a possible deformation evolution model in which structures develop along either radial or preferential trends, highlighting different volcanic conditions: (i) where radial patterns occur, the structures developed during volcanic inflation cycles with a closed magmatic conduit condition whereas (ii) clustered patterns are probably associated with a regional strain field that overcomes the local deformation field, a situation typical in the case of open-conduit activity.

Bacterial xylose isomerases from the mammal gut Bacteroidetes cluster function in Saccharomyces cerevisiae for effective xylose fermentation.

PubMed

Peng, Bingyin; Huang, Shuangcheng; Liu, Tingting; Geng, Anli

2015-05-17

Xylose isomerase (XI) catalyzes the conversion of xylose to xylulose, which is the key step for anaerobic ethanolic fermentation of xylose. Very few bacterial XIs can function actively in Saccharomyces cerevisiae. Here, we illustrate a group of XIs that would function for xylose fermentation in S. cerevisiae through phylogenetic analysis, recombinant yeast strain construction, and xylose fermentation. Phylogenetic analysis of deposited XI sequences showed that XI evolutionary relationship was highly consistent with the bacterial taxonomic orders and quite a few functional XIs in S. cerevisiae were clustered with XIs from mammal gut Bacteroidetes group. An XI from Bacteroides valgutus in this cluster was actively expressed in S. cerevisiae with an activity comparable to the fungal XI from Piromyces sp. Two XI genes were isolated from the environmental metagenome and they were clustered with XIs from environmental Bacteroidetes group. These two XIs could not be expressed in yeast with activity. With the XI from B. valgutus expressed in S. cerevisiae, background yeast strains were optimized by pentose metabolizing pathway enhancement and adaptive evolution in xylose medium. Afterwards, more XIs from the mammal gut Bacteroidetes group, including those from B. vulgatus, Tannerella sp. 6_1_58FAA_CT1, Paraprevotella xylaniphila and Alistipes sp. HGB5, were individually transformed into S. cerevisiae. The known functional XI from Orpinomyces sp. ukk1, a mammal gut fungus, was used as the control. All the resulting recombinant yeast strains were able to ferment xylose. The respiration-deficient strains harboring B. vulgatus and Alistipes sp. HGB5 XI genes respectively obtained specific xylose consumption rate of 0.662 and 0.704 g xylose gcdw(-1) h(-1), and ethanol specific productivity of 0.277 and 0.283 g ethanol gcdw(-1) h(-1), much comparable to those obtained by the control strain carrying Orpinomyces sp. ukk1 XI gene. This study demonstrated that XIs clustered in the mammal gut Bacteroidetes group were able to be expressed functionally in S. cerevisiae and background strain anaerobic adaptive evolution in xylose medium is essential for the screening of functional XIs. The methods outlined in this paper are instructive for the identification of novel XIs that are functional in S. cerevisiae.

Strain-Specific Protective Effect of the Immunity Induced by Live Malarial Sporozoites under Chloroquine Cover

PubMed Central

Wijayalath, Wathsala; Cheesman, Sandra; Tanabe, Kazuyuki; Handunnetti, Shiroma; Carter, Richard; Pathirana, Sisira

2012-01-01

The efficacy of a whole-sporozoite malaria vaccine would partly be determined by the strain-specificity of the protective responses against malarial sporozoites and liver-stage parasites. Evidence from previous reports were inconsistent, where some studies have shown that the protective immunity induced by irradiated or live sporozoites in rodents or humans were cross-protective and in others strain-specific. In the present work, we have studied the strain-specificity of live sporozoite-induced immunity using two genetically and immunologically different strains of Plasmodium cynomolgi, Pc746 and PcCeylon, in toque monkeys. Two groups of monkeys were immunized against live sporozoites of either the Pc746 (n = 5), or the PcCeylon (n = 4) strain, by the bites of 2–4 sporozoite-infected Anopheles tessellates mosquitoes per monkey under concurrent treatments with chloroquine and primaquine to abrogate detectable blood infections. Subsequently, a group of non-immunized monkeys (n = 4), and the two groups of immunized monkeys were challenged with a mixture of sporozoites of the two strains by the bites of 2–5 infective mosquitoes from each strain per monkey. In order to determine the strain-specificity of the protective immunity, the proportions of parasites of the two strains in the challenge infections were quantified using an allele quantification assay, Pyrosequencing™, based on a single nucleotide polymorphism (SNP) in the parasites’ circumsporozoite protein gene. The Pyrosequencing™ data showed that a significant reduction of parasites of the immunizing strain in each group of strain-specifically immunized monkeys had occurred, indicating a stronger killing effect on parasites of the immunizing strain. Thus, the protective immunity developed following a single, live sporozoite/chloroquine immunization, acted specifically against the immunizing strain and was, therefore, strain-specific. As our experiment does not allow us to determine the parasite stage at which the strain-specific protective immunity is directed, it is possible that the target of this immunity could be either the pre-erythrocytic stage, or the blood-stage, or both. PMID:23029282

Evaluation of an Immunochromatographic Test for Rapid and Reliable Serodiagnosis of Human Tularemia and Detection of Francisella tularensis-Specific Antibodies in Sera from Different Mammalian Species ▿

PubMed Central

Splettstoesser, W.; Guglielmo-Viret, V.; Seibold, E.; Thullier, P.

2010-01-01

Tularemia is a highly contagious infectious zoonosis caused by the bacterial agent Francisella tularensis. Serology is still considered to be a cornerstone in tularemia diagnosis due to the low sensitivity of bacterial culture and the lack of standardization in PCR methodology for the direct identification of the pathogen. We developed a novel immunochromatographic test (ICT) to efficiently detect F. tularensis-specific antibodies in sera from humans and other mammalian species (nonhuman primate, pig, and rabbit). This new tool requires none or minimal laboratory equipment, and the results are obtained within 15 min. When compared to the method of microagglutination, which was shown to be more specific than the enzyme-linked immunosorbent assay, the ICT had a sensitivity of 98.3% (58 positive sera were tested) and a specificity of 96.5% (58 negative sera were tested) on human sera. On animal sera, the overall sensitivity was 100% (22 positive sera were tested) and specificity was also 100% (70 negative sera were tested). This rapid test preferentially detects IgG antibodies that may occur early in the course of human tularemia, but further evaluation with human sera is important to prove that the ICT can be a valuable field test to support a presumptive diagnosis of tularemia. The ICT can also be a useful tool to monitor successful vaccination with subunit vaccines or live vaccine strains containing lipopolysaccharide (e.g., LVS) and to detect seropositive individuals or animals in outbreak situations or in the context of epidemiologic surveillance programs in areas of endemicity as recently recommended by the World Health Organization. PMID:20220165

Sporadic case of listeriosis associated with the consumption of a Listeria monocytogenes-contaminated 'Camembert' cheese.

PubMed

Gilot, P; Hermans, C; Yde, M; Gigi, J; Janssens, M; Genicot, A; André, P; Wauters, G

1997-09-01

Listeria monocytogenes is an intracellular gram-positive organism responsible for severe infections in both humans and animals. Whereas the food-borne transmission of listeriosis was demonstrated in several outbreaks, most cases of listeriosis occur sporadically and are rarely linked with consumption of contaminated foods. In this paper a case of septicaemia with L. monocytogenes in a 73-year-old immunocompromised man is described. Evidence for the association of this case of listeriosis with the consumption of a contaminated 'Camembert' cheese is provided by serotyping, esterase typing, DNA macrorestriction patterns analysis and level of virulence of the isolated strains for mice.

Quantitative framework for preferential flow initiation and partitioning

USGS Publications Warehouse

Nimmo, John R.

2016-01-01

A model for preferential flow in macropores is based on the short-range spatial distribution of soil matrix infiltrability. It uses elementary areas at two different scales. One is the traditional representative elementary area (REA), which includes a sufficient heterogeneity to typify larger areas, as for measuring field-scale infiltrability. The other, called an elementary matrix area (EMA), is smaller, but large enough to represent the local infiltrability of soil matrix material, between macropores. When water is applied to the land surface, each EMA absorbs water up to the rate of its matrix infiltrability. Excess water flows into a macropore, becoming preferential flow. The land surface then can be represented by a mesoscale (EMA-scale) distribution of matrix infiltrabilities. Total preferential flow at a given depth is the sum of contributions from all EMAs. Applying the model, one case study with multi-year field measurements of both preferential and diffuse fluxes at a specific depth was used to obtain parameter values by inverse calculation. The results quantify the preferential–diffuse partition of flow from individual storms that differed in rainfall amount, intensity, antecedent soil water, and other factors. Another case study provided measured values of matrix infiltrability to estimate parameter values for comparison and illustrative predictions. These examples give a self-consistent picture from the combination of parameter values, directions of sensitivities, and magnitudes of differences caused by different variables. One major practical use of this model is to calculate the dependence of preferential flow on climate-related factors, such as varying soil wetness and rainfall intensity.

The search for an elusive cutoff remains: Problems of binary classification of heavy drinking as an endpoint for alcohol clinical trials.

PubMed

Pearson, Matthew R; Bravo, Adrian J; Kirouac, Megan; Witkiewitz, Katie

2017-02-01

To examine whether a clinically meaningful alcohol consumption cutoff can be created for clinical samples, we used receiver operator characteristic (ROC) curves to derive gender-specific consumption cutoffs that maximized sensitivity and specificity in the prediction of a wide range of negative consequences from drinking. We conducted secondary data analyses using data from two large clinical trials targeting alcohol use disorders: Project MATCH (n=1726) and COMBINE (n=1383). In both studies, we found that the ideal cutoff for men and women that maximized sensitivity/specificity varied substantially both across different alcohol consumption variables and alcohol consequence outcomes. Further, the levels of sensitivity/specificity were poor across all consequences. These results fail to provide support for a clinically meaningful alcohol consumption cutoff and suggest that binary classification of levels of alcohol consumption is a poor proxy for maximizing sensitivity/specificity in the prediction of negative consequences from drinking. Future research examining consumption-consequence associations should take advantage of continuous measures of alcohol consumption and alternative approaches for assessing the link between levels of consumption and consequences (e.g., ecological momentary assessment). Clinical researchers should consider focusing more directly on the consequences they aim to reduce instead of relying on consumption as a proxy for more clinically meaningful outcomes. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The Search for an Elusive Cutoff Remains: Problems of Binary Classification of Heavy Drinking as an Endpoint for Alcohol Clinical Trials

PubMed Central

Pearson, Matthew R.; Bravo, Adrian J.; Kirouac, Megan; Witkiewitz, Katie

2017-01-01

Background To examine whether a clinically meaningful alcohol consumption cutoff can be created for clinical samples, we used receiver operator characteristic (ROC) curves to derive gender-specific consumption cutoffs that maximized sensitivity and specificity in the prediction of a wide range of negative consequences from drinking. Methods We conducted secondary data analyses using data from two large clinical trials targeting alcohol use disorders: Project MATCH (n = 1,726) and COMBINE (n = 1,383). Results In both studies, we found that the ideal cutoff for men and women that maximized sensitivity/specificity varied substantially both across different alcohol consumption variables and alcohol consequence outcomes. Further, the levels of sensitivity/specificity were poor across all consequences. Conclusions These results fail to provide support for a clinically meaningful alcohol consumption cutoff and suggest that binary classification of levels of alcohol consumption is a poor proxy for maximizing sensitivity/specificity in the prediction of negative consequences from drinking. Future research examining consumption-consequence associations should take advantage of continuous measures of alcohol consumption and alternative approaches for assessing the link between levels of consumption and consequences (e.g., ecological momentary assessment). Clinical researchers should consider focusing more directly on the consequences they aim to reduce instead of relying on consumption as a proxy for more clinically meaningful outcomes. PMID:28038361

A multiscale computational approach to dissect early events in the Erb family receptor mediated activation, differential signaling, and relevance to oncogenic transformations.

PubMed

Liu, Yingting; Purvis, Jeremy; Shih, Andrew; Weinstein, Joshua; Agrawal, Neeraj; Radhakrishnan, Ravi

2007-06-01

We describe a hierarchical multiscale computational approach based on molecular dynamics simulations, free energy-based molecular docking simulations, deterministic network-based kinetic modeling, and hybrid discrete/continuum stochastic dynamics protocols to study the dimer-mediated receptor activation characteristics of the Erb family receptors, specifically the epidermal growth factor receptor (EGFR). Through these modeling approaches, we are able to extend the prior modeling of EGF-mediated signal transduction by considering specific EGFR tyrosine kinase (EGFRTK) docking interactions mediated by differential binding and phosphorylation of different C-terminal peptide tyrosines on the RTK tail. By modeling signal flows through branching pathways of the EGFRTK resolved on a molecular basis, we are able to transcribe the effects of molecular alterations in the receptor (e.g., mutant forms of the receptor) to differing kinetic behavior and downstream signaling response. Our molecular dynamics simulations show that the drug sensitizing mutation (L834R) of EGFR stabilizes the active conformation to make the system constitutively active. Docking simulations show preferential characteristics (for wildtype vs. mutant receptors) in inhibitor binding as well as preferential enhancement of phosphorylation of particular substrate tyrosines over others. We find that in comparison to the wildtype system, the L834R mutant RTK preferentially binds the inhibitor erlotinib, as well as preferentially phosphorylates the substrate tyrosine Y1068 but not Y1173. We predict that these molecular level changes result in preferential activation of the Akt signaling pathway in comparison to the Erk signaling pathway for cells with normal EGFR expression. For cells with EGFR over expression, the mutant over activates both Erk and Akt pathways, in comparison to wildtype. These results are consistent with qualitative experimental measurements reported in the literature. We discuss these consequences in light of how the network topology and signaling characteristics of altered (mutant) cell lines are shaped differently in relationship to native cell lines.

Adolescent intake of caffeinated energy drinks does not affect adult alcohol consumption in C57BL/6 and BALB/c mice.

PubMed

Robins, Meridith T; DeFriel, Julia N; van Rijn, Richard M

2016-08-01

The rise in marketing and mass consumption of energy drink products by adolescents poses a largely unknown risk on adolescent development and drug reward. Yet, with increasing reports of acute health issues present in young adults who ingest large quantities of energy drinks alone or in combination with alcohol, the need to elucidate these potential risks is pressing. Energy drinks contain high levels of caffeine and sucrose; therefore, exposure to energy drinks may lead to changes in drug-related behaviors since caffeine and sucrose consumption activates similar brain pathways engaged by substances of abuse. With a recent study observing that adolescent caffeine consumption increased cocaine sensitivity, we sought to investigate how prolonged energy drink exposure in adolescence alters alcohol use and preference in adulthood. To do so, we utilized three different energy drink exposure paradigms and two strains of male mice (C57BL/6 and BALB/c) to monitor the effect of caffeine exposure via energy drinks in adolescence on adult alcohol intake. These paradigms included two models of volitional consumption of energy drinks or energy drink-like substances and one model of forced consumption of sucrose solutions with different caffeine concentrations. Following adolescent exposure to these solutions, alcohol intake was monitored in a limited-access, two-bottle choice between water and increasing concentrations of alcohol during adulthood. In none of the three models or two strains of mice did we observe that adolescent 'energy drink' consumption or exposure was correlated with changes in adult alcohol intake or preference. While our current preclinical results suggest that exposure to large amounts of caffeine does not alter future alcohol intake, differences in caffeine metabolism between mice and humans need to be considered before translating these results to humans. Copyright © 2016 Elsevier Inc. All rights reserved.

Transgenic Zebrafish Reveal Tissue-Specific Differences in Estrogen Signaling in Response to Environmental Water Samples

PubMed Central

Iwanowicz, Luke R.; Hung, Alice L.; Blazer, Vicki S.; Halpern, Marnie E.

2014-01-01

Background: Environmental endocrine disruptors (EEDs) are exogenous chemicals that mimic endogenous hormones such as estrogens. Previous studies using a zebrafish transgenic reporter demonstrated that the EEDs bisphenol A and genistein preferentially activate estrogen receptors (ERs) in the larval heart compared with the liver. However, it was not known whether the transgenic zebrafish reporter was sensitive enough to detect estrogens from environmental samples, whether environmental estrogens would exhibit tissue-specific effects similar to those of BPA and genistein, or why some compounds preferentially target receptors in the heart. Methods: We tested surface water samples using a transgenic zebrafish reporter with tandem estrogen response elements driving green fluorescent protein expression (5xERE:GFP). Reporter activation was colocalized with tissue-specific expression of ER genes by RNA in situ hybridization. Results: We observed selective patterns of ER activation in transgenic fish exposed to river water samples from the Mid-Atlantic United States, with several samples preferentially activating receptors in embryonic and larval heart valves. We discovered that tissue specificity in ER activation was due to differences in the expression of ER subtypes. ERα was expressed in developing heart valves but not in the liver, whereas ERβ2 had the opposite profile. Accordingly, subtype-specific ER agonists activated the reporter in either the heart valves or the liver. Conclusion: The use of 5xERE:GFP transgenic zebrafish revealed an unexpected tissue-specific difference in the response to environmentally relevant estrogenic compounds. Exposure to estrogenic EEDs in utero was associated with adverse health effects, with the potentially unanticipated consequence of targeting developing heart valves. Citation: Gorelick DA, Iwanowicz LR, Hung AL, Blazer VS, Halpern ME. 2014. Transgenic zebrafish reveal tissue-specific differences in estrogen signaling in response to environmental water samples. Environ Health Perspect 122:356–362; http://dx.doi.org/10.1289/ehp.1307329 PMID:24425189

Toward earlier detection of choroidal neovascularization secondary to age-related macular degeneration: multicenter evaluation of a preferential hyperacuity perimeter designed as a home device.

PubMed

Loewenstein, Anat; Ferencz, Joseph R; Lang, Yaron; Yeshurun, Itamar; Pollack, Ayala; Siegal, Ruth; Lifshitz, Tova; Karp, Joseph; Roth, Daniel; Bronner, Guri; Brown, Justin; Mansour, Sam; Friedman, Scott; Michels, Mark; Johnston, Richards; Rapp, Moshe; Havilio, Moshe; Rafaeli, Omer; Manor, Yair

2010-01-01

The primary purpose of this study was to evaluate the ability of a home device preferential hyperacuity perimeter to discriminate between patients with choroidal neovascularization (CNV) and intermediate age-related macular degeneration (AMD), and the secondary purpose was to investigate the dependence of sensitivity on lesion characteristics. All participants were tested with the home device in an unsupervised mode. The first part of this work was retrospective using tests performed by patients with intermediate AMD and newly diagnosed CNV. In the second part, the classifier was prospectively challenged with tests performed by patients with intermediate AMD and newly diagnosed CNV. The dependence of sensitivity on lesion characteristics was estimated with tests performed by patients with CNV of both parts. In 66 eyes with CNV and 65 eyes with intermediate AMD, both sensitivity and specificity were 0.85. In the retrospective part (34 CNV and 43 intermediate AMD), sensitivity and specificity were 0.85 +/- 0.12 (95% confidence interval) and 0.84 +/- 0.11 (95% confidence interval), respectively. In the prospective part (32 CNV and 22 intermediate AMD), sensitivity and specificity were 0.84 +/- 0.13 (95% confidence interval) and 0.86 +/- 0.14 (95% confidence interval), respectively. Chi-square analysis showed no dependence of sensitivity on type (P = 0.44), location (P = 0.243), or size (P = 0.73) of the CNV lesions. A home device preferential hyperacuity perimeter has good sensitivity and specificity in discriminating between patients with newly diagnosed CNV and intermediate AMD. Sensitivity is not dependent on lesion characteristics.

Using a periclinal chimera to unravel layer-specific gene expression in plants

PubMed Central

Filippis, Ioannis; Lopez-Cobollo, Rosa; Abbott, James; Butcher, Sarah; Bishop, Gerard J

2013-01-01

Plant organs are made from multiple cell types, and defining the expression level of a gene in any one cell or group of cells from a complex mixture is difficult. Dicotyledonous plants normally have three distinct layers of cells, L1, L2 and L3. Layer L1 is the single layer of cells making up the epidermis, layer L2 the single cell sub-epidermal layer and layer L3 constitutes the rest of the internal cells. Here we show how it is possible to harvest an organ and characterise the level of layer-specific expression by using a periclinal chimera that has its L1 layer from Solanum pennellii and its L2 and L3 layers from Solanum lycopersicum. This is possible by measuring the level of the frequency of species-specific transcripts. RNA-seq analysis enabled the genome-wide assessment of whether a gene is expressed in the L1 or L2/L3 layers. From 13 277 genes that are expressed in both the chimera and the parental lines and with at least one polymorphism between the parental alleles, we identified 382 genes that are preferentially expressed in L1 in contrast to 1159 genes in L2/L3. Gene ontology analysis shows that many genes preferentially expressed in L1 are involved in cutin and wax biosynthesis, whereas numerous genes that are preferentially expressed in L2/L3 tissue are associated with chloroplastic processes. These data indicate the use of such chimeras and provide detailed information on the level of layer-specific expression of genes. PMID:23725542

Molecular Structure of Photosynthetic Microbial Biofuels for Improved Engine Combustion and Emissions Characteristics

PubMed Central

Hellier, Paul; Purton, Saul; Ladommatos, Nicos

2015-01-01

The metabolic engineering of photosynthetic microbes for production of novel hydrocarbons presents an opportunity for development of advanced designer biofuels. These can be significantly more sustainable, throughout the production-to-consumption lifecycle, than the fossil fuels and crop-based biofuels they might replace. Current biofuels, such as bioethanol and fatty acid methyl esters, have been developed primarily as drop-in replacements for existing fossil fuels, based on their physical properties and autoignition characteristics under specific combustion regimes. However, advances in the genetic engineering of microalgae and cyanobacteria, and the application of synthetic biology approaches offer the potential of designer strains capable of producing hydrocarbons and oxygenates with specific molecular structures. Furthermore, these fuel molecules can be designed for higher efficiency of energy release and lower exhaust emissions during combustion. This paper presents a review of potential fuel molecules from photosynthetic microbes and the performance of these possible fuels in modern internal combustion engines, highlighting which modifications to the molecular structure of such fuels may enhance their suitability for specific combustion regimes. PMID:25941673

Molecular structure of photosynthetic microbial biofuels for improved engine combustion and emissions characteristics.

PubMed

Hellier, Paul; Purton, Saul; Ladommatos, Nicos

2015-01-01

The metabolic engineering of photosynthetic microbes for production of novel hydrocarbons presents an opportunity for development of advanced designer biofuels. These can be significantly more sustainable, throughout the production-to-consumption lifecycle, than the fossil fuels and crop-based biofuels they might replace. Current biofuels, such as bioethanol and fatty acid methyl esters, have been developed primarily as drop-in replacements for existing fossil fuels, based on their physical properties and autoignition characteristics under specific combustion regimes. However, advances in the genetic engineering of microalgae and cyanobacteria, and the application of synthetic biology approaches offer the potential of designer strains capable of producing hydrocarbons and oxygenates with specific molecular structures. Furthermore, these fuel molecules can be designed for higher efficiency of energy release and lower exhaust emissions during combustion. This paper presents a review of potential fuel molecules from photosynthetic microbes and the performance of these possible fuels in modern internal combustion engines, highlighting which modifications to the molecular structure of such fuels may enhance their suitability for specific combustion regimes.

Survey on the possibility of introducing new energy to regional development plans

NASA Astrophysics Data System (ADS)

1988-03-01

This report covers nationwide large-scale resort plans and at the same time studies the possibility of introducing new energy systems, mainly cogeneration, and their effects. Japanese industrial structure is rapidly moving toward information and service areas, and the development of resorts has become very active. With the increase of resort demands, much is expected of resort development as a means of regional promotion. Special features of energy consumption in resort facilities are that annual demand is large, that energy consumption fluctuates greatly, and that energy supply cost is high. These features are especially conspicuous in smaller facilities. Most suited for resort lodging facilities is a co-generation system, especially a diesel engine system. This system is expected to conserve energy; but to promote this system, it is necessary to revise the preferential tax treatment and Fire Service Act to meet the actual circumstances, and to develop a highly reliable system that can be operated unattended. An economical system in view of overall costs is also essential.

Listeria monocytogenes Strains Underrepresented during Selective Enrichment with an ISO Method Might Dominate during Passage through Simulated Gastric Fluid and In Vitro Infection of Caco-2 Cells

PubMed Central

Zilelidou, Evangelia; Karmiri, Christina-Vasiliki; Zoumpopoulou, Georgia; Mavrogonatou, Eleni; Kletsas, Dimitris; Tsakalidou, Effie; Papadimitriou, Konstantinos; Drosinos, Eleftherios

2016-01-01

ABSTRACT Various Listeria monocytogenes strains may contaminate a single food product, potentially resulting in simultaneous exposure of consumers to multiple strains. However, due to bias in strain recovery, L. monocytogenes strains isolated from foods by selective enrichment (SE) might not always represent those that can better survive the immune system of a patient. We investigated the effect of cocultivation in tryptic soy broth with 0.6% yeast extract (TSB-Y) at 10°C for 8 days on (i) the detection of L. monocytogenes strains during SE with the ISO 11290-1:1996/Amd 1:2004 protocol and (ii) the in vitro virulence of strains toward the Caco-2 human colon epithelial cancer cell line following exposure to simulated gastric fluid (SGF; pH 2.0)-HCl (37°C). We determined whether the strains which were favored by SE would be effective competitors under the conditions of challenges related to gastrointestinal passage of the pathogen. Interstrain competition of L. monocytogenes in TSB-Y determined the relative population of each strain at the beginning of SE. This in turn impacted the outcome of SE (i.e., favoring survival of competitors with better fitness) and the levels exposed subsequently to SGF. However, strong growth competitors could be outcompeted after SGF exposure and infection of Caco-2 cells by strains outgrown in TSB-Y and underdetected (or even missed) during enrichment. Our data demonstrate a preferential selection of certain L. monocytogenes strains during enrichments, often not reflecting a selective advantage of strains during infection. These findings highlight a noteworthy scenario associated with the difficulty of matching the source of infection (food) with the L. monocytogenes isolate appearing to be the causative agent during listeriosis outbreak investigations. IMPORTANCE This report is relevant to understanding the processes involved in selection and prevalence of certain L. monocytogenes strains in different environments (i.e., foods or sites of humans exposed to the pathogen). It highlights the occurrence of multiple strains in the same food as an important aspect contributing to mismatches between clinical isolates and infection sources during listeriosis outbreak investigations. PMID:27637880

Strain rate dependent calcite microfabric evolution at natural conditions

NASA Astrophysics Data System (ADS)

Rogowitz, Anna; Grasemann, Bernhard; Huet, Benjamin; Habler, Gerlinde

2014-05-01

Crystal plastic deformational behaviour of calcite has been the focus of many experimental studies. Different strain rates, pressure and temperature conditions have been addressed to investigate a wide range of deformation regimes. However, a direct comparison with natural fault rocks remains difficult because of extreme differences between experimental and natural strain rates. A flanking structure developed in almost pure calcite marble on Syros (Cyclades, Greece). Due to rotation of a planar feature (crack) a heterogeneous strain field in the surrounding area occurred resulting in different strain domains and the formation of the flanking structure. Assuming that deformation was active continuously during the development of the flanking structure, the different strain domains correspond to different strain-rate domains. The outcrop thus represents the final state of a natural experiment and gives us a great opportunity to get natural constraints on strain rate dependent deformation behaviour of calcite. Comparing the microfabrics in the 1 to 2.5 cm thick shear zone and the surrounding host rocks, which formed under the same metamorphic conditions but with different strain rates, is the central focus of this study. Due to the extreme variation in strain and strain rate, different microstructures and textures can be observed corresponding to different deformation mechanisms. With increasing strain rate we observe a change in dominant deformation mechanism from dislocation glide to dislocation creep and finally diffusion creep. Additionally, a change from subgrain rotation to bulging recrystallization can be observed in the dislocation creep regime. Crystallographic preferred orientations (CPO) and the grade of intracrystalline deformation were measured on a FEI Quanta 3D FEG instrument equipped with an EDAX Digiview IV EBSD camera. At all strain rates clear CPOs developed leading to the assumption that calcite preferentially deforms within the dislocation creep field. However, we can also find clear evidence for grain size sensitive deformation mechanisms at smaller grain sizes (3.6 μm) consistent with experimental observations and determined flaw laws. The results of this study are compared with experimental data, closing the gap between experimental and natural geological strain rates.

Seroprevalence and molecular epidemiology of EAST1 gene-carrying Escherichia coli from diarrheal patients and raw meats.

PubMed

Sukkua, Kannika; Manothong, Somruthai; Sukhumungoon, Pharanai

2017-03-31

Several Escherichia coli pathotypes have been reported in Thailand; however, information on enteroaggregative heat-stable enterotoxin 1 (EAST1)-carrying E. coli (EAST1-EC) is insufficient. Previous reports show that consumption of raw meats causes diarrheagenic E. coli infections. In this study, we investigated the seroprevalence and genetic relationship of EAST1-EC from clinical and raw meat samples. Diarrheal patients and raw meat samples were investigated for the presence of EAST1-EC by performing polymerase chain reaction (PCR) to detect astA. Serotyping, antimicrobial susceptibility tests, and PCR-based phylogenetic group assay were performed. Molecular epidemiology of E. coli strains from clinical and raw meat samples was determined using repetitive element-PCR typing, BOX-PCR, and ERIC2-PCR. Results showed that 11.2% (17/152) of clinical samples and 53.3% (16/30) of raw meat samples had EAST1-EC. In all, 24 and 36 EAST1-EC strains were successfully isolated from 17 clinical and 16 raw meat samples, respectively. These strains had astA but did not possess the indicative genes of other E. coli pathotypes and were therefore classified as EAST1-EC. Most of these strains were multidrug resistant and were classified into nine serogroups. Molecular genotyping showed identical DNA fingerprint among EAST1-EC serotype O15 strains from clinical and raw chicken samples, suggesting that they were derived from the same bacterial clone. Our results indicated a high prevalence of multidrug-resistant EAST1-EC strains in clinical and environmental samples in Thailand belonging to nine serogroups. Moreover, the study highlighted the close association between infections caused by EAST1-EC serotype O15 and raw meat consumption.

Preferential particle concentration in wall-bounded turbulence with zero skin friction

NASA Astrophysics Data System (ADS)

Yang, Kun; Zhao, Lihao; Andersson, Helge I.

2017-11-01

Inertial particles dispersed in turbulence distribute themselves unevenly. Besides their tendency to segregate near walls, they also concentrate preferentially in wall-parallel planes. We explore the latter phenomenon in a tailor-made flow with the view to examine the homogeneity and anisotropy of particle clustering in the absence of mean shear as compared with conventional, i.e., sheared, wall turbulence. Inertial particles with some different Stokes numbers are suspended in a turbulent Couette-Poiseuille flow, in which one of the walls moves such that the shear rate vanishes at that wall. The anisotropies of the velocity and vorticity fluctuations are therefore qualitatively different from those at the opposite non-moving wall, along which quasi-coherent streaky structures prevail, similarly as in turbulent pipe and channel flows. Preferential particle concentration is observed near both walls. The inhomogeneity of the concentration is caused by the strain-vorticity selection mechanism, whereas the anisotropy originates from coherent flow structures. In order to analyse anisotropic clustering, a two-dimensional Shannon entropy method is developed. Streaky particle structures are observed near the stationary wall where the flow field resembles typical wall-turbulence, whereas particle clusters near the moving friction-free wall are similar to randomly oriented clusters in homogeneous isotropic turbulence, albeit with a modest streamwise inclination. In the absence of mean-shear and near-wall streaks, the observed anisotropy is ascribed to the imprint of large-scale flow structures which reside in the bulk flow and are global in nature.

Probiotics, immunomodulation, and health benefits.

PubMed

Gill, Harsharn; Prasad, Jaya

2008-01-01

Probiotics are defined as live microorganisms that, when administered in adequate amount, confer a health benefit on the host. Amongst the many benefits associated with the consumption of probiotics, modulation of the immune system has received the most attention. Several animal and human studies have provided unequivocal evidence that specific strains of probiotics are able to stimulate as well as regulate several aspects of natural and acquired immune responses. There is also evidence that intake of probiotics is effective in the prevention and/or management of acute gastroenteritis and rotavirus diarrhoea, antibiotic-associated diarrhoea and intestinal inflammatory disorders such as Crohn's disease and pouchitis, and paediatric atopic disorders. The efficacy of probiotics against bacterial infections and immunological disorders such as adult asthma, cancers, diabetes, and arthritis in humans remains to be proven. Also, major gaps exist in our knowledge about the mechanisms by which probiotics modulate immune function. Optimum dose, frequency and duration of treatment required for different conditions in different population groups also remains to be determined. Different probiotic strains vary in their ability to modulate the immune system and therefore efficacy of each strain needs to be carefully demonstrated through rigorously designed (randomised, double-blind, placebo-controlled) studies. This chapter provides an over view of the immunomodulatory effects of probiotics in health and disease, and discusses possible mechanisms through which probiotics mediate their disparate effects.

Beneficial metabolic effects of selected probiotics on diet-induced obesity and insulin resistance in mice are associated with improvement of dysbiotic gut microbiota.

PubMed

Alard, Jeanne; Lehrter, Véronique; Rhimi, Moez; Mangin, Irène; Peucelle, Véronique; Abraham, Anne-Laure; Mariadassou, Mahendra; Maguin, Emmanuelle; Waligora-Dupriet, Anne-Judith; Pot, Bruno; Wolowczuk, Isabelle; Grangette, Corinne

2016-05-01

Alterations in gut microbiota composition and diversity were suggested to play a role in the development of obesity, a chronic subclinical inflammatory condition. We here evaluated the impact of oral consumption of a monostrain or multi-strain probiotic preparation in high-fat diet-induced obese mice. We observed a strain-specific effect and reported dissociation between the capacity of probiotics to dampen adipose tissue inflammation and to limit body weight gain. A multi-strain mixture was able to improve adiposity, insulin resistance and dyslipidemia through adipose tissue immune cell-remodelling, mainly affecting macrophages. At the gut level, the mixture modified the uptake of fatty acids and restored the expression level of the short-chain fatty acid receptor GPR43. These beneficial effects were associated with changes in the microbiota composition, such as the restoration of the abundance of Akkermansia muciniphila and Rikenellaceae and the decrease of other taxa like Lactobacillaceae. Using an in vitro gut model, we further showed that the probiotic mixture favours the production of butyrate and propionate. Our findings provide crucial clues for the design and use of more efficient probiotic preparations in obesity management and may bring new insights into the mechanisms by which host-microbe interactions govern such protective effects. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Prevalence and distribution of Vibrio parahaemolyticus in finfish from Cochin (south India).

PubMed

Sudha, Santha; Divya, Puthenkandathil S; Francis, Bini; Hatha, Ammanamveetil A M

2012-01-01

Finfish samples obtained from four retail outlets in Cochin between June 2009 and June 2010 were investigated for the occurrence of Vibrio parahaemolyticus. A total of 182 samples were collected and suspect isolates were identified using standard biochemical tests and were further confirmed by a species-specific tlh gene. V. parahaemolyticus was detected in 45.1% of samples, with demersal fish being more affected than pelagic species. The bacterium was isolated more frequently from the skin and gills of pelagic fish, while the intestine yielded greater numbers of V. parahaemolyticus in demersal fish. The highest incidence of antibiotic resistance was recorded against ampicillin and streptomycin, followed by carbenicillin, cefpodoxime, cephalothin, colistin and amoxycillin; the lowest was against nalidixic acid, tetracycline, chloramphenicol and ciprofloxacin. Multiple drug resistance was prevalent among isolates. Although only a fraction of strains are pathogenic for humans, the time-temperature abuse in markets provides ample scope for these strains to multiply to dangerous levels. The multidrug resistant nature of the strains adds to the gravity of the problem. High V. parahaemolyticus incidence rates in market finfish samples from areas in and around Cochin clearly indicates that control measures should be adopted to reduce post-harvest contamination in seafood and time-temperature abuse in markets to diminish the risk of V. parahaemolyticus infection associated with seafood destined for human consumption.

Heavy metals in wild marine fish from South China Sea: levels, tissue- and species-specific accumulation and potential risk to humans.

PubMed

Liu, Jin-Ling; Xu, Xiang-Rong; Ding, Zhen-Hua; Peng, Jia-Xi; Jin, Ming-Hua; Wang, You-Shao; Hong, Yi-Guo; Yue, Wei-Zhong

2015-10-01

Heavy metal pollution in marine fish has become an important worldwide concern, not only because of the threat to fish in general, but also due to human health risks associated with fish consumption. To investigate the occurrence of heavy metals in marine fish species from the South China Sea, 14 fish species were collected along the coastline of Hainan China during the spring of 2012 and examined for species- and tissue-specific accumulation. The median concentrations of Cd, Cr, Cu, Zn, Pb and As in muscle tissue of the examined fish species were not detectable (ND), 2.02, 0.24, 2.64, 0.025, and 1.13 mg kg(-1) wet weight, respectively. Levels of Cu, Zn, Cd and Cr were found to be higher in the liver and gills than in muscle, while Pb was preferentially accumulated in the gills. Differing from other heavy metals, As did not exhibit tissue-specific accumulation. Inter-species differences of heavy metal accumulation were attributed to the different habitat and diet characteristics of marine fish. Human dietary exposure assessment suggested that the amounts of both Cr and As in marine wild fish collected from the sites around Hainan, China were not compliant with the safety standard of less than 79.2 g d(-1) for wild marine fish set by the Joint FAO/WHO Expert Committee on Food Additives. Further research to identify the explicit sources of Cr and As in marine fish from South China Sea should be established.

Structure and Receptor Binding of the Hemagglutinin from a Human H6N1 Influenza Virus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tzarum, Netanel; de Vries, Robert P.; Zhu, Xueyong

Avian influenza viruses that cause infection and are transmissible in humans involve changes in the receptor binding site (RBS) of the viral hemagglutinin (HA) that alter receptor preference from α2-3-linked (avian-like) to α2-6-linked (human-like) sialosides. A human case of avian-origin H6N1 influenza virus was recently reported, but the molecular mechanisms contributing to it crossing the species barrier are unknown. We find that, although the H6 HA RBS contains D190V and G228S substitutions that potentially promote human receptor binding, recombinant H6 HA preferentially binds α2-3-linked sialosides, indicating no adaptation to human receptors. Crystal structures of H6 HA with avian and humanmore » receptor analogs reveal that H6 HA preferentially interacts with avian receptor analogs. Lastly, this binding mechanism differs from other HA subtypes due to a unique combination of RBS residues, highlighting additional variation in HA-receptor interactions and the challenges in predicting which influenza strains and subtypes can infect humans and cause pandemics.« less

Hydrodynamic clustering of droplets in turbulence

NASA Astrophysics Data System (ADS)

Kunnen, Rudie; Yavuz, Altug; van Heijst, Gertjan; Clercx, Herman

2017-11-01

Small, inertial particles are known to cluster in turbulent flows: particles are centrifuged out of eddies and gather in the strain-dominated regions. This so-called preferential concentration is reflected in the radial distribution function (RDF; a quantitative measure of clustering). We study clustering of water droplets in a loudspeaker-driven turbulence chamber. We track the motion of droplets in 3D and calculate the RDF. At moderate scales (a few Kolmogorov lengths) we find the typical power-law scaling of preferential concentration in the RDF. However, at even smaller scales (a few droplet diameters), we encounter a hitherto unobserved additional clustering. We postulate that the additional clustering is due to hydrodynamic interactions, an effect which is typically disregarded in modeling. Using a perturbative expansion of inertial effects in a Stokes-flow description of two interacting spheres, we obtain an expression for the RDF which indeed includes the additional clustering. The additional clustering enhances the collision probability of droplets, which enhances their growth rate due to coalescence. The additional clustering is thus an essential effect in precipitation modeling.

Structure and Receptor Binding of the Hemagglutinin from a Human H6N1 Influenza Virus

DOE PAGES

Tzarum, Netanel; de Vries, Robert P.; Zhu, Xueyong; ...

2015-03-11

Avian influenza viruses that cause infection and are transmissible in humans involve changes in the receptor binding site (RBS) of the viral hemagglutinin (HA) that alter receptor preference from α2-3-linked (avian-like) to α2-6-linked (human-like) sialosides. A human case of avian-origin H6N1 influenza virus was recently reported, but the molecular mechanisms contributing to it crossing the species barrier are unknown. We find that, although the H6 HA RBS contains D190V and G228S substitutions that potentially promote human receptor binding, recombinant H6 HA preferentially binds α2-3-linked sialosides, indicating no adaptation to human receptors. Crystal structures of H6 HA with avian and humanmore » receptor analogs reveal that H6 HA preferentially interacts with avian receptor analogs. Lastly, this binding mechanism differs from other HA subtypes due to a unique combination of RBS residues, highlighting additional variation in HA-receptor interactions and the challenges in predicting which influenza strains and subtypes can infect humans and cause pandemics.« less

The first isolation and molecular characterization of Toxoplasma gondii from horses in Serbia.

PubMed

Klun, Ivana; Uzelac, Aleksandra; Villena, Isabelle; Mercier, Aurélien; Bobić, Branko; Nikolić, Aleksandra; Rajnpreht, Irena; Opsteegh, Marieke; Aubert, Dominique; Blaga, Radu; van der Giessen, Joke; Djurković-Djaković, Olgica

2017-04-04

Consumption of undercooked or insufficiently cured meat is a major risk factor for human infection with Toxoplasma gondii. Although horsemeat is typically consumed rare or undercooked, information on the risk of T. gondii from infected horse meat to humans is scarce. Here, we present the results of a study to determine the presence of T. gondii infection in slaughter horses in Serbia, and to attempt to isolate viable parasites. The study included horses from all regions of Serbia slaughtered at two abattoirs between June 2013 and June 2015. Blood sera were tested for the presence of specific IgG T. gondii antibodies by the modified agglutination test (MAT), and samples of trypsin-digested heart tissue were bioassayed in mice. Cyst-positive mouse brain homogenates were subjected to DNA extraction and T. gondii strains were genotyped using 15 microsatellite markers (MS). A total of 105 slaughter horses were sampled. At the 1:6 cut-off 48.6% of the examined horses were seropositive, with the highest titre being 1:400. Viable parasites were isolated from two grade type mares; both parasite isolates (RS-Eq39 and RS-Eq40) were T. gondii type III, and both displayed an increased lethality for mice with successive passages. These are the first cases of isolation of T. gondii from horses in Serbia. When compared with a worldwide collection of 61 type III and type III-like strains, isolate RS-Eq39 showed a combination of MS lengths similar to a strain isolated from a duck in Iran, and isolate RS-Eq40 was identical in all markers to three strains isolated from a goat from Gabon, a sheep from France and a pig from Portugal. Interestingly, the source horses were one seronegative and one weakly seropositive. The isolation of viable T. gondii parasites from slaughter horses points to horsemeat as a potential source of human infection, but the fact that viable parasites were isolated from horses with only a serological trace of T. gondii infection presents further evidence that serology may not be adequate to assess the risk of toxoplasmosis from horsemeat consumption. Presence of T. gondii type III in Serbia sheds more light into the potential origin of this archetypal lineage in Europe.

Cross-reactive antigens and lectin as determinants of symbiotic specificity in the Rhizobium-clover association.

PubMed Central

Dazzo, F B; Hubbell, D H

1975-01-01

Cross-reactive antigens of clover roots and Rhizobium trifolii were detected on their cell surfaces by tube agglutination, immunofluorescent, and radioimmunoassay techniques. Anti-clover root antiserum had a higher agglutinating titer with infective strains of R. trifolii than with noninfective strains. The root antiserum previously adsorbed with noninfective R. trifolii cells remained reactive only with infective cells, including infective revertants. When adsorbed with infective cells, the root antiserum was reactive with neither infective nor noninfective cells. Other Rhizobium species incapable of infecting clover did not demonstrate surface antigens cross-reactive with clover. Radioimmunoassay indicated twice as much antigenic cross-reactivity of clover roots and R. trifolii 403 (infective) than R. trifolii Bart A (noninfective). Immunofluorescence with anti-R. trifolii (infective) antiserum was detected on the exposed surface of the root epidermal cells and diminished at the root meristem. The immunofluorescent crossreaction on clover roots was totally removed by adsorption of anti-R. trifolii (infective) antiserum with encapsulated infective cells but not with noninfective cells. The cross-reactive capsular antigens from R. trifolii strains were extracted and purified. The ability of these antigens to induce clover root hair deformation was much greater when they were obtained from the infective than noninfective strains. The cross-reactive capsular antigen of R. trifolii 403 was characterized as a high-molecular-weight (greater than 4.6 times 10(6) daltons), beta-linked, acidic heteropolysaccharide containing 2-deoxyglucose, galactose, glucose, and glucuronic acid. A soluble, nondialyzable, substance (clover lectin) capable of binding to the cross-reactive antigen and agglutinating only infective cells of R. trifolii was extracted from white clover seeds. This lectin was sensitive to heat, Pronase, and trypsin. inhibition studies indicated that 2-deoxyglucose was the most probable haptenic determinant of the cross-reactive capsular antigen capable of binding to the root antiserum and the clover lectin. A model is proposed suggesting the preferential adsorption of infective versus noninfective cells of R. trifolii on the surface of clover roots by a cross-bridging of their common surface antigens with a multivalent clover lectin. Images PMID:55100

Application of the Modular Approach to an In-House Validation Study of Real-Time PCR Methods for the Detection and Serogroup Determination of Verocytotoxigenic Escherichia coli ▿ †

PubMed Central

Kagkli, Dafni-Maria; Weber, Thomas P.; Van den Bulcke, Marc; Folloni, Silvia; Tozzoli, Rosangela; Morabito, Stefano; Ermolli, Monica; Gribaldo, Laura; Van den Eede, Guy

2011-01-01

European Commission regulation 2073/2005 on the microbiological criteria for food requires that Escherichia coli is monitored as an indicator of hygienic conditions. Since verocytotoxigenic E. coli (VTEC) strains often cause food-borne infections by the consumption of raw food, the Biological Hazards (BIOHAZ) panel of the European Food Safety Authority (EFSA) recommended their monitoring in food as well. In particular, VTEC strains belonging to serogroups such as O26, O103, O111, O145, and O157 are known causative agents of several human outbreaks. Eight real-time PCR methods for the detection of E. coli toxin genes and their variants (stx1, stx2), the intimin gene (eae), and five serogroup-specific genes have been proposed by the European Reference Laboratory for VTEC (EURL-VTEC) as a technical specification to the European Normalization Committee (CEN TC275/WG6). Here we applied a “modular approach” to the in-house validation of these PCR methods. The modular approach subdivides an analytical process into separate parts called “modules,” which are independently validated based on method performance criteria for a limited set of critical parameters. For the VTEC real-time PCR module, the following parameters are being assessed: specificity, dynamic range, PCR efficiency, and limit of detection (LOD). This study describes the modular approach for the validation of PCR methods to be used in food microbiology, using single-target plasmids as positive controls and showing their applicability with food matrices. PMID:21856838

Temporal Effects on Internal Fluorescence Emissions Associated with Aflatoxin Contamination from Corn Kernel Cross-Sections Inoculated with Toxigenic and Atoxigenic Aspergillus flavus.

PubMed

Hruska, Zuzana; Yao, Haibo; Kincaid, Russell; Brown, Robert L; Bhatnagar, Deepak; Cleveland, Thomas E

2017-01-01

Non-invasive, easy to use and cost-effective technology offers a valuable alternative for rapid detection of carcinogenic fungal metabolites, namely aflatoxins, in commodities. One relatively recent development in this area is the use of spectral technology. Fluorescence hyperspectral imaging, in particular, offers a potential rapid and non-invasive method for detecting the presence of aflatoxins in maize infected with the toxigenic fungus Aspergillus flavus . Earlier studies have shown that whole maize kernels contaminated with aflatoxins exhibit different spectral signatures from uncontaminated kernels based on the external fluorescence emission of the whole kernels. Here, the effect of time on the internal fluorescence spectral emissions from cross-sections of kernels infected with toxigenic and atoxigenic A. flavus , were examined in order to elucidate the interaction between the fluorescence signals emitted by some aflatoxin contaminated maize kernels and the fungal invasion resulting in the production of aflatoxins. First, the difference in internal fluorescence emissions between cross-sections of kernels incubated in toxigenic and atoxigenic inoculum was assessed. Kernels were inoculated with each strain for 5, 7, and 9 days before cross-sectioning and imaging. There were 270 kernels (540 halves) imaged, including controls. Second, in a different set of kernels (15 kernels/group; 135 total), the germ of each kernel was separated from the endosperm to determine the major areas of aflatoxin accumulation and progression over nine growth days. Kernels were inoculated with toxigenic and atoxigenic fungal strains for 5, 7, and 9 days before the endosperm and germ were separated, followed by fluorescence hyperspectral imaging and chemical aflatoxin determination. A marked difference in fluorescence intensity was shown between the toxigenic and atoxigenic strains on day nine post-inoculation, which may be a useful indicator of the location of aflatoxin contamination. This finding suggests that both, the fluorescence peak shift and intensity as well as timing, may be essential in distinguishing toxigenic and atoxigenic fungi based on spectral features. Results also reveal a possible preferential difference in the internal colonization of maize kernels between the toxigenic and atoxigenic strains of A. flavus suggesting a potential window for differentiating the strains based on fluorescence spectra at specific time points.

Temporal Effects on Internal Fluorescence Emissions Associated with Aflatoxin Contamination from Corn Kernel Cross-Sections Inoculated with Toxigenic and Atoxigenic Aspergillus flavus

PubMed Central

Hruska, Zuzana; Yao, Haibo; Kincaid, Russell; Brown, Robert L.; Bhatnagar, Deepak; Cleveland, Thomas E.

2017-01-01

Non-invasive, easy to use and cost-effective technology offers a valuable alternative for rapid detection of carcinogenic fungal metabolites, namely aflatoxins, in commodities. One relatively recent development in this area is the use of spectral technology. Fluorescence hyperspectral imaging, in particular, offers a potential rapid and non-invasive method for detecting the presence of aflatoxins in maize infected with the toxigenic fungus Aspergillus flavus. Earlier studies have shown that whole maize kernels contaminated with aflatoxins exhibit different spectral signatures from uncontaminated kernels based on the external fluorescence emission of the whole kernels. Here, the effect of time on the internal fluorescence spectral emissions from cross-sections of kernels infected with toxigenic and atoxigenic A. flavus, were examined in order to elucidate the interaction between the fluorescence signals emitted by some aflatoxin contaminated maize kernels and the fungal invasion resulting in the production of aflatoxins. First, the difference in internal fluorescence emissions between cross-sections of kernels incubated in toxigenic and atoxigenic inoculum was assessed. Kernels were inoculated with each strain for 5, 7, and 9 days before cross-sectioning and imaging. There were 270 kernels (540 halves) imaged, including controls. Second, in a different set of kernels (15 kernels/group; 135 total), the germ of each kernel was separated from the endosperm to determine the major areas of aflatoxin accumulation and progression over nine growth days. Kernels were inoculated with toxigenic and atoxigenic fungal strains for 5, 7, and 9 days before the endosperm and germ were separated, followed by fluorescence hyperspectral imaging and chemical aflatoxin determination. A marked difference in fluorescence intensity was shown between the toxigenic and atoxigenic strains on day nine post-inoculation, which may be a useful indicator of the location of aflatoxin contamination. This finding suggests that both, the fluorescence peak shift and intensity as well as timing, may be essential in distinguishing toxigenic and atoxigenic fungi based on spectral features. Results also reveal a possible preferential difference in the internal colonization of maize kernels between the toxigenic and atoxigenic strains of A. flavus suggesting a potential window for differentiating the strains based on fluorescence spectra at specific time points. PMID:28966606

Variable effects of chronic intermittent ethanol exposure on ethanol drinking in a genetically diverse mouse cohort.

PubMed

Lopez, Marcelo F; Miles, Michael F; Williams, Robert W; Becker, Howard C

2017-02-01

The BXD family of mice were generated by crossing and inbreeding ethanol-preferring C57BL/6J and ethanol-avoiding DBA/2J strains that differ greatly in genome sequence and other behaviors. This study evaluated variations in the level of voluntary ethanol intake in a cohort of 42 BXD strains and both progenitor strains using a model of alcohol dependence and relapse drinking. A total of 119 BXDs (85 males, 34 females) (n ∼ 4 per genotype; 1/genotype/sex/group) were evaluated along with males from both progenitor strains (n = 14-15/genotype). Mice were evaluated for intake using limited access (2 h/day) 2-bottle (15% v/v ethanol vs. water) model for 6 weeks (baseline intake). Each animal received 4 weekly cycles of chronic intermittent ethanol (CIE) vapor exposure (CIE group) or air control exposure (CTL group) (16 h/day × 4 days) interleaved by 5-day drinking test cycles. Blood ethanol concentrations (BEC) ranged from 150 to 300 mg/dl across genotypes. Baseline intake varied greatly among cases-from ∼0.8 to ∼2.9 g/kg. As expected, CIE exposure induced a significant increase in ethanol drinking in C57BL/6J relative to baseline as well as air controls that remained relatively stable over the four test cycles. In contrast, DBA/2J cases did not show a significant increase in consumption. Heritability of variation in baseline consumption, calculated from C57BL/6J and DBA/2J strains is about 54% but this increases following treatment to 60-80%. As expected from the marked difference between progenitors, ethanol intake and level of escalation varied greatly among BXDs after exposure (∼-1.3 to 2.6 g/kg). Interestingly, the magnitude and direction of changes in ethanol intake did not relate to BEC values of the preceding CIE exposure cycle. Overall, these data indicate significant variation in consumption and even escalation, much of it under genetic control, following repeated CIE treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

Variable Effects of Chronic Intermittent Ethanol Exposure on Ethanol Drinking in a Genetically Diverse Mouse Cohort

PubMed Central

Lopez, Marcelo F.; Miles, Michael F.; Williams, Robert W.; Becker, Howard C.

2016-01-01

The BXD family of mice were generated by crossing and inbreeding ethanol-preferring C57BL/6J and ethanol-avoiding DBA/2J strains that differ greatly in genome sequence and other behaviors. This study evaluated variations in the level of voluntary ethanol intake in a cohort of 42 BXD strains and both progenitor strains using a model of alcohol dependence and relapse drinking. A total of 119 BXDs (85 males, 34 females) (n ~ 4 per genotype; 1/genotype/sex/group) were evaluated along with males from both progenitor strains (n = 14–15/genotype). Mice were evaluated for intake using limited access (2 hr/day) 2-bottle (15% v/v ethanol vs. water) model for 6 weeks (baseline intake). Each animal received 4 weekly cycles of chronic intermittent ethanol (CIE) vapor exposure (CIE group) or air control exposure (CTL group) (16 hr/day × 4 days) interleaved by 5-day drinking test cycles. Blood ethanol concentrations (BEC) ranged from 150–300 mg/dl across genotypes. Baseline intake varied greatly among cases—from ~0.8 to ~2.9 g/kg. As expected, CIE exposure induced a significant increase in ethanol drinking in C57BL/6J relative to baseline as well as air controls that remained relatively stable over the four test cycles. In contrast, DBA/2J cases did not show a significant increase in consumption. Heritability of variation in baseline consumption, calculated from C57BL/6J and DBA/2J strains is about 54% but this increases following treatment to 60–80%. As expected from the marked difference between progenitors, ethanol intake and level of escalation varied greatly among BXDs after exposure (~-1.3 to ~2.6 g/kg). Interestingly, the magnitude and direction of changes in ethanol intake did not relate to BEC values of the preceding CIE exposure cycle. Overall, these data indicate significant variation in consumption and even escalation, much of it under genetic control, following repeated CIE treatment. PMID:27793543

Functional Specialization in the Human Brain Estimated By Intrinsic Hemispheric Interaction

PubMed Central

Wang, Danhong; Buckner, Randy L.

2014-01-01

The human brain demonstrates functional specialization, including strong hemispheric asymmetries. Here specialization was explored using fMRI by examining the degree to which brain networks preferentially interact with ipsilateral as opposed to contralateral networks. Preferential within-hemisphere interaction was prominent in the heteromodal association cortices and minimal in the sensorimotor cortices. The frontoparietal control network exhibited strong within-hemisphere interactions but with distinct patterns in each hemisphere. The frontoparietal control network preferentially coupled to the default network and language-related regions in the left hemisphere but to attention networks in the right hemisphere. This arrangement may facilitate control of processing functions that are lateralized. Moreover, the regions most linked to asymmetric specialization also display the highest degree of evolutionary cortical expansion. Functional specialization that emphasizes processing within a hemisphere may allow the expanded hominin brain to minimize between-hemisphere connectivity and distribute domain-specific processing functions. PMID:25209275

Preferential attachment and growth dynamics in complex systems

NASA Astrophysics Data System (ADS)

Yamasaki, Kazuko; Matia, Kaushik; Buldyrev, Sergey V.; Fu, Dongfeng; Pammolli, Fabio; Riccaboni, Massimo; Stanley, H. Eugene

2006-09-01

Complex systems can be characterized by classes of equivalency of their elements defined according to system specific rules. We propose a generalized preferential attachment model to describe the class size distribution. The model postulates preferential growth of the existing classes and the steady influx of new classes. According to the model, the distribution changes from a pure exponential form for zero influx of new classes to a power law with an exponential cut-off form when the influx of new classes is substantial. Predictions of the model are tested through the analysis of a unique industrial database, which covers both elementary units (products) and classes (markets, firms) in a given industry (pharmaceuticals), covering the entire size distribution. The model’s predictions are in good agreement with the data. The paper sheds light on the emergence of the exponent τ≈2 observed as a universal feature of many biological, social and economic problems.

Stability of Proteins in Carbohydrates and Other Additives during Freezing: The Human Growth Hormone as a Case Study.

PubMed

Arsiccio, Andrea; Pisano, Roberto

2017-09-21

Molecular dynamics is here used to elucidate the mechanism of protein stabilization by carbohydrates and other additives during freezing. More specifically, we used molecular dynamics simulations to obtain a quantitative estimation of the capability of various cryoprotectants to preserve a model protein, the human growth hormone, against freezing stresses. Three mechanisms were investigated, preferential exclusion, water replacement, and vitrification. Model simulations were finally validated upon experimental data in terms of the ability of excipients to prevent protein aggregation. Overall, we found that the preferential exclusion and vitrification mechanisms are important during the whole freezing process, while water replacement becomes dominant only toward the end of the cryoconcentration phase. The disaccharides were found to be the most efficient excipients, in regard to both preferential exclusion and water replacement. Moreover, sugars were in general more efficient than other excipients, such as glycine or sorbitol.

Influence of the Envelope gp120 Phe 43 Cavity on HIV-1 Sensitivity to Antibody-Dependent Cell-Mediated Cytotoxicity Responses

PubMed Central

Prévost, Jérémie; Zoubchenok, Daria; Richard, Jonathan; Veillette, Maxime; Pacheco, Beatriz; Coutu, Mathieu; Brassard, Nathalie; Parsons, Matthew S.; Ruxrungtham, Kiat; Bunupuradah, Torsak; Tovanabutra, Sodsai; Hwang, Kwan-Ki; Moody, M. Anthony; Haynes, Barton F.; Bonsignori, Mattia; Sodroski, Joseph; Kaufmann, Daniel E.; Shaw, George M.; Chenine, Agnès L.

2017-01-01

ABSTRACT HIV-1-infected cells presenting envelope glycoproteins (Env) in the CD4-bound conformation on their surface are preferentially targeted by antibody-dependent cellular-mediated cytotoxicity (ADCC). HIV-1 has evolved sophisticated mechanisms to avoid the exposure of Env ADCC epitopes by downregulating CD4 and by limiting the overall amount of Env on the cell surface. In HIV-1, substitution of large residues such as histidine or tryptophan for serine 375 (S375H/W) in the gp120 Phe 43 cavity, where Phe 43 of CD4 contacts gp120, results in the spontaneous sampling of an Env conformation closer to the CD4-bound state. While residue S375 is well conserved in the majority of group M HIV-1 isolates, CRF01_AE strains have a naturally occurring histidine at this position (H375). Interestingly, CRF01_AE is the predominant circulating strain in Thailand, where the RV144 trial took place. In this trial, which resulted in a modest degree of protection, ADCC responses were identified as being part of the correlate of protection. Here we investigate the influence of the Phe 43 cavity on ADCC responses. Filling this cavity with a histidine or tryptophan residue in Env with a natural serine residue at this position (S375H/W) increased the susceptibility of HIV-1-infected cells to ADCC. Conversely, the replacement of His 375 by a serine residue (H375S) within HIV-1 CRF01_AE decreased the efficiency of the ADCC response. Our results raise the intriguing possibility that the presence of His 375 in the circulating strain where the RV144 trial was held contributed to the observed vaccine efficacy. IMPORTANCE HIV-1-infected cells presenting Env in the CD4-bound conformation on their surface are preferentially targeted by ADCC mediated by HIV-positive (HIV+) sera. Here we show that the gp120 Phe 43 cavity modulates the propensity of Env to sample this conformation and therefore affects the susceptibility of infected cells to ADCC. CRF01_AE HIV-1 strains have an unusual Phe 43 cavity-filling His 375 residue, which increases the propensity of Env to sample the CD4-bound conformation, thereby increasing susceptibility to ADCC. PMID:28100618

Enzyme activities and substrate degradation during white rot fungi growth on sugar-cane straw in a solid state fermentation.

PubMed

Ortega, G M; Martinez, E O; González, P C; Betancourt, D; Otero, M A

1993-03-01

Two strains of Pleurotus spp., grown in solid state fermentation on sugar-cane straw, degraded the dry matter by 50% after 60 days. The rate of substrate consumption and the dry weight of fruiting bodies decreased in consecutive flushings. Both strains vigorously attacked hemicellulose (80% of total degradation) and lignin (70%). Fruiting bodies were rich in protein and lipids, and had a low content of carbohydrates and ash.

Alcohol brand use of youth-appealing advertising and consumption by youth and adults.

PubMed

Padon, Alisa A; Rimal, Rajiv N; Siegel, Michael; DeJong, William; Naimi, Timothy S; JernFigan, David H

2018-02-05

Youth exposure to alcohol marketing has been shown to be an important contributor to the problem of underage drinking in the U.S. More work is needed on identifying and minimizing content with particular appeal to youth. We tested the association between the youth-appeal of marketing content of televised alcohol advertisements and the brand-specific alcohol consumption of both underage youth and adults. We used existing data from three sources: a brand-specific alcohol consumption survey among underage youth ( N =1032), a brand-specific alcohol consumption survey among adults ( N ~13,000), and an analysis of content appealing to youth (CAY) in a sample of televised alcohol advertisements ( n =96) aired during the youth survey. The association between CAY scores for the 96 alcohol ads and youth (age 13-20) versus adult (age 21+) consumption of those ads' brands was tested through bivariate and multivariate models. Brand CAY scores were (a) positively associated with brand-specific youth consumption after controlling for adult brand consumption; (b) positively associated with a ratio of youth-toadult brand-specific consumption; and (c) not associated with adult brand consumption. Alcohol brands with youth-appealing advertising are consumed more often by youth than adults, indicating that these ads may be more persuasive to relatively younger audiences, and that youth are not simply mirroring adult consumption patterns in their choice of brands. Future research should consider the content of alcohol advertising when testing marketing effects on youth drinking, and surveillance efforts might focus on brands popular among youth.

Chlorinated and ultraviolet radiation -treated reclaimed irrigation water is the source of Aeromonas found in vegetables used for human consumption.

PubMed

Latif-Eugenín, Fadua; Beaz-Hidalgo, Roxana; Silvera-Simón, Carolina; Fernandez-Cassi, Xavi; Figueras, María J

2017-04-01

Wastewater is increasingly being recognized as a key water resource, and reclaimed water (or treated wastewater) is used for irrigating vegetables destined for human consumption. The aim of the present study was to determine the diversity and prevalence of Aeromonas spp. both in reclaimed water used for irrigation and in the three types of vegetables irrigated with that water. Seven of the 11 (63.6%) samples of reclaimed water and all samples of vegetables were positive for the presence of Aeromonas. A total of 216 Aeromonas isolates were genotyped and corresponded to 132 different strains that after identification by sequencing the rpoD gene belonged to 10 different species. The prevalence of the species varied depending on the type of sample. In the secondary treated reclaimed water A. caviae and A. media dominated (91.4%) while A. salmonicida, A. media, A. allosaccharophila and A. popoffii represented 74.0% of the strains in the irrigation water. In vegetables, A. caviae (75.0%) was the most common species, among which a strain isolated from lettuce had the same genotype (ERIC pattern) as a strain recovered from the irrigation water. Furthermore, the same genotype of the species A. sanarellii was recovered from parsley and tomatoes demonstrating that irrigation water was the source of contamination and confirming the risk for public health. Copyright © 2017 Elsevier Inc. All rights reserved.

Stretching Your Energetic Budget: How Tendon Compliance Affects the Metabolic Cost of Running

PubMed Central

Uchida, Thomas K.; Hicks, Jennifer L.; Dembia, Christopher L.; Delp, Scott L.

2016-01-01

Muscles attach to bones via tendons that stretch and recoil, affecting muscle force generation and metabolic energy consumption. In this study, we investigated the effect of tendon compliance on the metabolic cost of running using a full-body musculoskeletal model with a detailed model of muscle energetics. We performed muscle-driven simulations of running at 2–5 m/s with tendon force–strain curves that produced between 1 and 10% strain when the muscles were developing maximum isometric force. We computed the average metabolic power consumed by each muscle when running at each speed and with each tendon compliance. Average whole-body metabolic power consumption increased as running speed increased, regardless of tendon compliance, and was lowest at each speed when tendon strain reached 2–3% as muscles were developing maximum isometric force. When running at 2 m/s, the soleus muscle consumed less metabolic power at high tendon compliance because the strain of the tendon allowed the muscle fibers to operate nearly isometrically during stance. In contrast, the medial and lateral gastrocnemii consumed less metabolic power at low tendon compliance because less compliant tendons allowed the muscle fibers to operate closer to their optimal lengths during stance. The software and simulations used in this study are freely available at simtk.org and enable examination of muscle energetics with unprecedented detail. PMID:26930416