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Sample records for abiotic factors temperature

  1. Abiotic factors influence plant storage lipid accumulation and composition.

    PubMed

    Singer, Stacy D; Zou, Jitao; Weselake, Randall J

    2016-02-01

    The demand for plant-derived oils has increased substantially over the last decade, and is sure to keep growing. While there has been a surge in research efforts to produce plants with improved oil content and quality, in most cases the enhancements have been small. To add further complexity to this situation, substantial differences in seed oil traits among years and field locations have indicated that plant lipid biosynthesis is also influenced to a large extent by multiple environmental factors such as temperature, drought, light availability and soil nutrients. On the molecular and biochemical levels, the expression and/or activities of fatty acid desaturases, as well as diacylglycerol acyltransferase 1, have been found to be affected by abiotic factors, suggesting that they play a role in the lipid content and compositional changes seen under abiotic stress conditions. Unfortunately, while only a very small number of strategies have been developed as of yet to minimize these environmental effects on the production of storage lipids, it is clear that this feat will be of the utmost importance for developing superior oil crops with the capability to perform in a consistent manner in field conditions in the future. PMID:26795146

  2. Abiotic environmental factors influencing blowfly colonisation patterns in the field.

    PubMed

    George, Kelly A; Archer, Melanie S; Toop, Tes

    2013-06-10

    The accuracy of minimum post-mortem interval (mPMI) estimates usually hinges upon the ability of forensic entomologists to predict the conditions under which calliphorids will colonise bodies. However, there can be delays between death and colonisation due to poorly understood abiotic and biotic factors, hence the need for a mPMI. To quantify the importance of various meteorological and light-level factors, beef liver baits were placed in the field (Victoria, Australia) on 88 randomly selected days over 3 years in all seasons and observed every 60-90 min for evidence of colonisation. Baits were exposed during daylight, and the following parameters were measured: barometric pressure, light intensity, wind speed, ambient temperature, relative humidity and rainfall. Collected data were analysed using backward LR logistic regression to produce an equation of colonisation probability. This type of analysis removes factors with the least influence on colonisation in successive steps until all remaining variables significantly increase the accuracy of predicting colonisation presence or absence. Ambient temperature was a positive predictor variable (an increase in temperature increased the probability of calliphorid colonisation). Relative humidity was a negative predictor variable (an increase in humidity decreased the probability of calliphorid colonisation). Barometric pressure, light intensity, wind speed and rainfall did not enhance the accuracy of the probability model; however, analysis of species activity patterns suggests that heavy rainfall and strong wind speeds inhibit calliphorid colonisation. PMID:23683914

  3. The Plant Heat Stress Transcription Factors (HSFs): Structure, Regulation, and Function in Response to Abiotic Stresses

    PubMed Central

    Guo, Meng; Liu, Jin-Hong; Ma, Xiao; Luo, De-Xu; Gong, Zhen-Hui; Lu, Ming-Hui

    2016-01-01

    Abiotic stresses such as high temperature, salinity, and drought adversely affect the survival, growth, and reproduction of plants. Plants respond to such unfavorable changes through developmental, physiological, and biochemical ways, and these responses require expression of stress-responsive genes, which are regulated by a network of transcription factors (TFs), including heat stress transcription factors (HSFs). HSFs play a crucial role in plants response to several abiotic stresses by regulating the expression of stress-responsive genes, such as heat shock proteins (Hsps). In this review, we describe the conserved structure of plant HSFs, the identification of HSF gene families from various plant species, their expression profiling under abiotic stress conditions, regulation at different levels and function in abiotic stresses. Despite plant HSFs share highly conserved structure, their remarkable diversification across plants reflects their numerous functions as well as their integration into the complex stress signaling and response networks, which can be employed in crop improvement strategies via biotechnological intervention. PMID:26904076

  4. Influence of salinity and temperature on the physiology of Limia melanonotata (Cyprinodontiformes: Poeciliidae): A search for abiotic factors limiting insular distribution in Hispaniola

    USGS Publications Warehouse

    Haney, D.C.; Walsh, S.J.

    2003-01-01

    We investigated salinity and temperature effects on routine metabolic rate (RMR), temperature tolerance (CTMax, critical thermal maximum), and salinity tolerance of Limia melanonotata, a poecliid fish that occurs in west-central inland waters of Hispaniola. Routine metabolic rate and CTMax were measured in fish acclimated to three salinities (0, 30, and 60 ppt) and temperatures (25??, 30??, and 35??C) for nine temperature-salinity combinations. Salinity and temperature did not significantly interact in their effect on RMR. For combined salinity acclimations, adjusted RMR (ANCOVA) was significantly lower at 25??C than either 30?? or 35??C. For combined temperature acclimations, mean RMR was significantly lower at 60 ppt than either 0 or 30 ppt. Salinity and temperature had a significant interactive effect on temperature tolerance. Mean CTMax was significantly higher at 30?? than 25??C at all salinities, but at 35??C was significantly higher than at 25?? or 30??C only among fish acclimated in fresh water. Fish exposed to a chronic increase in salinity experienced most mortality in a salinity range of 70-107 ppt, with females exhibiting greater salinity tolerance than males. Limia melanonotata approaches the upper extreme in salinity and temperature tolerances known for poeciliids. Our results also suggest that L. melanonotata may reduce energy expenditures at environmental extremes to tolerate harsh conditions for extended periods. Despite its curythermal and euryhaline adaptations, L. melanonotata has a relatively restricted inland range in Hispaniola and is unknown from inshore brackish or marine habitats. The present distribution of this species and congeners may be the result of a combination of factors that include historical zoogeography and ecological requirements.

  5. Effects of Abiotic Factors on HIPV-Mediated Interactions between Plants and Parasitoids

    PubMed Central

    Becker, Christine; Desneux, Nicolas; Monticelli, Lucie; Fernandez, Xavier; Michel, Thomas; Lavoir, Anne-Violette

    2015-01-01

    In contrast to constitutively emitted plant volatiles (PV), herbivore-induced plant volatiles (HIPV) are specifically emitted by plants when afflicted with herbivores. HIPV can be perceived by parasitoids and predators which parasitize or prey on the respective herbivores, including parasitic hymenoptera. HIPV act as signals and facilitate host/prey detection. They comprise a blend of compounds: main constituents are terpenoids and “green leaf volatiles.” Constitutive emission of PV is well known to be influenced by abiotic factors like temperature, light intensity, water, and nutrient availability. HIPV share biosynthetic pathways with constitutively emitted PV and might therefore likewise be affected by abiotic conditions. However, the effects of abiotic factors on HIPV-mediated biotic interactions have received only limited attention to date. HIPV being influenced by the plant's growing conditions could have major implications for pest management. Quantitative and qualitative changes in HIPV blends may improve or impair biocontrol. Enhanced emission of HIPV may attract a larger number of natural enemies. Reduced emission rates or altered compositions, however, may render blends imperceptible to parasitoides and predators. Predicting the outcome of these changes is highly important for food production and for ecosystems affected by global climate change. PMID:26788501

  6. The impact of individual and combined abiotic factors on daily otolith growth in a coral reef fish

    PubMed Central

    Wenger, Amelia S.; Whinney, James; Taylor, Brett; Kroon, Frederieke

    2016-01-01

    Coral reefs are increasingly subjected to both local and global stressors, however, there is limited information on how reef organisms respond to their combined effects under natural conditions. This field study examined the growth response of the damselfish Neopomacentrus bankieri to the individual and combined effects of multiple abiotic factors. Turbidity, temperature, tidal movement, and wave action were recorded every 10 minutes for four months, after which the daily otolith growth of N. bankieri was aligned with corresponding abiotic conditions. Temperature was the only significant driver of daily otolith increment width, with increasing temperatures resulting in decreasing width. Although tidal movement was not a significant driver of increment width by itself, the combined effect of tidal movement and temperature had a greater negative effect on growth than temperature alone. Our results indicate that temperature can drive changes in growth even at very fine scales, and demonstrate that the cumulative impact of abiotic factors can be substantially greater than individual effects. As abiotic factors continue to change in intensity and duration, the combined impacts of them will become increasingly important drivers of physiological and ecological change. PMID:27350589

  7. The impact of individual and combined abiotic factors on daily otolith growth in a coral reef fish.

    PubMed

    Wenger, Amelia S; Whinney, James; Taylor, Brett; Kroon, Frederieke

    2016-01-01

    Coral reefs are increasingly subjected to both local and global stressors, however, there is limited information on how reef organisms respond to their combined effects under natural conditions. This field study examined the growth response of the damselfish Neopomacentrus bankieri to the individual and combined effects of multiple abiotic factors. Turbidity, temperature, tidal movement, and wave action were recorded every 10 minutes for four months, after which the daily otolith growth of N. bankieri was aligned with corresponding abiotic conditions. Temperature was the only significant driver of daily otolith increment width, with increasing temperatures resulting in decreasing width. Although tidal movement was not a significant driver of increment width by itself, the combined effect of tidal movement and temperature had a greater negative effect on growth than temperature alone. Our results indicate that temperature can drive changes in growth even at very fine scales, and demonstrate that the cumulative impact of abiotic factors can be substantially greater than individual effects. As abiotic factors continue to change in intensity and duration, the combined impacts of them will become increasingly important drivers of physiological and ecological change. PMID:27350589

  8. Effects of biotic and abiotic factors on phenotypic partitioning of wing morphology and development in Sclerodermus pupariae (hymenoptera: bethylidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wing phenotype polymorphism is commonly observed in insects, yet little is known about the influence of environmental cues on the development or expression of the alternative phenotypes. Here, we examined the effects of biotic and abiotic factors including temperature, photoperiod, light intensity,...

  9. Effect of abiotic factors on initiation of red flour beetle (Coleoptera: Tenebrionidae) flight.

    PubMed

    Perez-Mendoza, Joel; Campbell, James F; Throne, James E

    2014-02-01

    Traps baited with pheromones are used to monitor the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera-Tenebrionidae), populations in flour mills to aid in making pest management decisions, but the factors that influence T. castaneum movement are not fully understood. We investigated the impact of photoperiod, light intensity, temperature, and relative humidity on flight initiation. The percentage of adults initiating flight reached a maximum at 30 -35 degrees C, and then fell to zero at 22.5 and 45 degrees C. Only 2% of beetles flew in complete darkness, and the number of beetles initiating flight increased to 41% under 18 h of light and then decreased slightly to 37% under 24 h of light. Rates of flight initiation did not vary with light intensities from 1,784 to 4,356 lux or relative humidities from 25 to 85%. Thus, temperature and photoperiod are the main abiotic factors tested that impact flight initiation in T castaneum, which have broad ranges of temperatures and photoperiods over which they can fly. The current results should be useful in helping to interpret trap catches based on abiotic conditions during the trapping period, and the results should be useful in helping to understand T. castaneum movement outside grain storages and processing facilities and their potential to infest structures. PMID:24665734

  10. Abiotic and microbiotic factors controlling biofilm formation by thermophilic sporeformers.

    PubMed

    Zhao, Yu; Caspers, Martien P M; Metselaar, Karin I; de Boer, Paulo; Roeselers, Guus; Moezelaar, Roy; Nierop Groot, Masja; Montijn, Roy C; Abee, Tjakko; Kort, Remco

    2013-09-01

    One of the major concerns in the production of dairy concentrates is the risk of contamination by heat-resistant spores from thermophilic bacteria. In order to acquire more insight in the composition of microbial communities occurring in the dairy concentrate industry, a bar-coded 16S amplicon sequencing analysis was carried out on milk, final products, and fouling samples taken from dairy concentrate production lines. The analysis of these samples revealed the presence of DNA from a broad range of bacterial taxa, including a majority of mesophiles and a minority of (thermophilic) spore-forming bacteria. Enrichments of fouling samples at 55°C showed the accumulation of predominantly Brevibacillus and Bacillus, whereas enrichments at 65°C led to the accumulation of Anoxybacillus and Geobacillus species. Bacterial population analysis of biofilms grown using fouling samples as an inoculum indicated that both Anoxybacillus and Geobacillus preferentially form biofilms on surfaces at air-liquid interfaces rather than on submerged surfaces. Three of the most potent biofilm-forming strains isolated from the dairy factory industrial samples, including Geobacillus thermoglucosidans, Geobacillus stearothermophilus, and Anoxybacillus flavithermus, have been characterized in detail with respect to their growth conditions and spore resistance. Strikingly, Geobacillus thermoglucosidans, which forms the most thermostable spores of these three species, is not able to grow in dairy intermediates as a pure culture but appears to be dependent for growth on other spoilage organisms present, probably as a result of their proteolytic activity. These results underscore the importance of abiotic and microbiotic factors in niche colonization in dairy factories, where the presence of thermophilic sporeformers can affect the quality of end products. PMID:23851093

  11. Abiotic and Microbiotic Factors Controlling Biofilm Formation by Thermophilic Sporeformers

    PubMed Central

    Zhao, Yu; Caspers, Martien P. M.; Metselaar, Karin I.; de Boer, Paulo; Roeselers, Guus; Moezelaar, Roy; Nierop Groot, Masja; Montijn, Roy C.; Abee, Tjakko

    2013-01-01

    One of the major concerns in the production of dairy concentrates is the risk of contamination by heat-resistant spores from thermophilic bacteria. In order to acquire more insight in the composition of microbial communities occurring in the dairy concentrate industry, a bar-coded 16S amplicon sequencing analysis was carried out on milk, final products, and fouling samples taken from dairy concentrate production lines. The analysis of these samples revealed the presence of DNA from a broad range of bacterial taxa, including a majority of mesophiles and a minority of (thermophilic) spore-forming bacteria. Enrichments of fouling samples at 55°C showed the accumulation of predominantly Brevibacillus and Bacillus, whereas enrichments at 65°C led to the accumulation of Anoxybacillus and Geobacillus species. Bacterial population analysis of biofilms grown using fouling samples as an inoculum indicated that both Anoxybacillus and Geobacillus preferentially form biofilms on surfaces at air-liquid interfaces rather than on submerged surfaces. Three of the most potent biofilm-forming strains isolated from the dairy factory industrial samples, including Geobacillus thermoglucosidans, Geobacillus stearothermophilus, and Anoxybacillus flavithermus, have been characterized in detail with respect to their growth conditions and spore resistance. Strikingly, Geobacillus thermoglucosidans, which forms the most thermostable spores of these three species, is not able to grow in dairy intermediates as a pure culture but appears to be dependent for growth on other spoilage organisms present, probably as a result of their proteolytic activity. These results underscore the importance of abiotic and microbiotic factors in niche colonization in dairy factories, where the presence of thermophilic sporeformers can affect the quality of end products. PMID:23851093

  12. The Effects of Abiotic Factors on Induced Volatile Emissions in Corn Plants1

    PubMed Central

    Gouinguené, Sandrine P.; Turlings, Ted C.J.

    2002-01-01

    Many plants respond to herbivory by releasing a specific blend of volatiles that is attractive to natural enemies of the herbivores. In corn (Zea mays), this induced odor blend is mainly composed of terpenoids and indole. The induced signal varies with plant species and genotype, but little is known about the variation due to abiotic factors. Here, we tested the effect of soil humidity, air humidity, temperature, light, and fertilization rate on the emission of induced volatiles in young corn plants. Each factor was tested separately under constant conditions for the other factors. Plants released more when standing in dry soil than in wet soil, whereas for air humidity, the optimal release was found at around 60% relative humidity. Temperatures between 22°C and 27°C led to a higher emission than lower or higher temperatures. Light intensity had a dramatic effect. The emission of volatiles did not occur in the dark and increased steadily with an increase in the light intensity. An experiment with an unnatural light-dark cycle showed that the release was fully photophase dependent. Fertilization also had a strong positive effect; the emission of volatiles was minimal when plants were grown under low nutrition, even when results were corrected for plant biomass. Changes in all abiotic factors caused small but significant changes in the relative ratios among the different compounds (quality) in the induced odor blends, except for air humidity. Hence, climatic conditions and nutrient availability can be important factors in determining the intensity and variability in the release of induced plant volatiles. PMID:12114583

  13. Potential utilization of NAC transcription factors to enhance abiotic stress tolerance in plants by biotechnological approach.

    PubMed

    Tran, Lam-Son Phan; Nishiyama, Rie; Yamaguchi-Shinozaki, Kazuko; Shinozaki, Kazuo

    2010-01-01

    Abiotic stresses such as extreme temperature, drought, high salinity, cold and waterlogging often result in significant losses to the yields of economically important crops. Plants constantly exposed to capricious conditions have adapted at the molecular, cellular, physiological and biochemical level, enabling them to survive and cope with adverse environmental stresses. NAC (NAM, ATAF and CUC) transcription factors (TFs), which constitute one of the largest families of plant-specific TFs, have been reported to enhance tolerance against various stresses, such as drought, high salinity and cold, in a number of plants. In this review the NAC TF family will be described and the potential use of NAC TFs in development of improved stress tolerant transgenic crops will be discussed. PMID:21912210

  14. Effects of Abiotic Factors on the Phylogenetic Diversity of Bacterial Communities in Acidic Thermal Springs▿

    PubMed Central

    Mathur, Jayanti; Bizzoco, Richard W.; Ellis, Dean G.; Lipson, David A.; Poole, Alexander W.; Levine, Richard; Kelley, Scott T.

    2007-01-01

    Acidic thermal springs offer ideal environments for studying processes underlying extremophile microbial diversity. We used a carefully designed comparative analysis of acidic thermal springs in Yellowstone National Park to determine how abiotic factors (chemistry and temperature) shape acidophile microbial communities. Small-subunit rRNA gene sequences were PCR amplified, cloned, and sequenced, by using evolutionarily conserved bacterium-specific primers, directly from environmental DNA extracted from Amphitheater Springs and Roaring Mountain sediment samples. Energy-dispersive X-ray spectroscopy, X-ray diffraction, and colorimetric assays were used to analyze sediment chemistry, while an optical emission spectrometer was used to evaluate water chemistry and electronic probes were used to measure the pH, temperature, and Eh of the spring waters. Phylogenetic-statistical analyses found exceptionally strong correlations between bacterial community composition and sediment mineral chemistry, followed by weaker but significant correlations with temperature gradients. For example, sulfur-rich sediment samples contained a high diversity of uncultured organisms related to Hydrogenobaculum spp., while iron-rich sediments were dominated by uncultured organisms related to a diverse array of gram-positive iron oxidizers. A detailed analysis of redox chemistry indicated that the available energy sources and electron acceptors were sufficient to support the metabolic potential of Hydrogenobaculum spp. and iron oxidizers, respectively. Principal-component analysis found that two factors explained 95% of the genetic diversity, with most of the variance attributable to mineral chemistry and a smaller fraction attributable to temperature. PMID:17220248

  15. Effects of abiotic factors on the phylogenetic diversity of bacterial communities in acidic thermal springs.

    PubMed

    Mathur, Jayanti; Bizzoco, Richard W; Ellis, Dean G; Lipson, David A; Poole, Alexander W; Levine, Richard; Kelley, Scott T

    2007-04-01

    Acidic thermal springs offer ideal environments for studying processes underlying extremophile microbial diversity. We used a carefully designed comparative analysis of acidic thermal springs in Yellowstone National Park to determine how abiotic factors (chemistry and temperature) shape acidophile microbial communities. Small-subunit rRNA gene sequences were PCR amplified, cloned, and sequenced, by using evolutionarily conserved bacterium-specific primers, directly from environmental DNA extracted from Amphitheater Springs and Roaring Mountain sediment samples. Energy-dispersive X-ray spectroscopy, X-ray diffraction, and colorimetric assays were used to analyze sediment chemistry, while an optical emission spectrometer was used to evaluate water chemistry and electronic probes were used to measure the pH, temperature, and E(h) of the spring waters. Phylogenetic-statistical analyses found exceptionally strong correlations between bacterial community composition and sediment mineral chemistry, followed by weaker but significant correlations with temperature gradients. For example, sulfur-rich sediment samples contained a high diversity of uncultured organisms related to Hydrogenobaculum spp., while iron-rich sediments were dominated by uncultured organisms related to a diverse array of gram-positive iron oxidizers. A detailed analysis of redox chemistry indicated that the available energy sources and electron acceptors were sufficient to support the metabolic potential of Hydrogenobaculum spp. and iron oxidizers, respectively. Principal-component analysis found that two factors explained 95% of the genetic diversity, with most of the variance attributable to mineral chemistry and a smaller fraction attributable to temperature. PMID:17220248

  16. Global Expressions Landscape of NAC Transcription Factor Family and Their Responses to Abiotic Stresses in Citrullus lanatus

    PubMed Central

    Lv, Xiaolong; Lan, Shanrong; Guy, Kateta Malangisha; Yang, Jinghua; Zhang, Mingfang; Hu, Zhongyuan

    2016-01-01

    Watermelon (Citrullus lanatus) is one xerophyte that has relative higher tolerance to drought and salt stresses as well as more sensitivity to cold stress, compared with most model plants. These characteristics facilitate it a potential model crop for researches on salt, drought or cold tolerance. In this study, a genome-wide comprehensive analysis of the ClNAC transcription factor (TF) family was carried out for the first time, to investigate their transcriptional profiles and potential functions in response to these abiotic stresses. The expression profiling analysis reveals that several NAC TFs are highly responsive to abiotic stresses and development, for instance, subfamily IV NACs may play roles in maintaining water status under drought or salt conditions, as well as water and metabolites conduction and translocation toward fruit. In contrast, rapid and negative responses of most of the ClNACs to low-temperature adversity may be related to the sensitivity to cold stress. Crosstalks among these abiotic stresses and hormone (abscisic acid and jasmonic acid) pathways were also discussed based on the expression of ClNAC genes. Our results will provide useful insights for the functional mining of NAC family in watermelon, as well as into the mechanisms underlying abiotic tolerance in other cash crops. PMID:27491393

  17. Global Expressions Landscape of NAC Transcription Factor Family and Their Responses to Abiotic Stresses in Citrullus lanatus.

    PubMed

    Lv, Xiaolong; Lan, Shanrong; Guy, Kateta Malangisha; Yang, Jinghua; Zhang, Mingfang; Hu, Zhongyuan

    2016-01-01

    Watermelon (Citrullus lanatus) is one xerophyte that has relative higher tolerance to drought and salt stresses as well as more sensitivity to cold stress, compared with most model plants. These characteristics facilitate it a potential model crop for researches on salt, drought or cold tolerance. In this study, a genome-wide comprehensive analysis of the ClNAC transcription factor (TF) family was carried out for the first time, to investigate their transcriptional profiles and potential functions in response to these abiotic stresses. The expression profiling analysis reveals that several NAC TFs are highly responsive to abiotic stresses and development, for instance, subfamily IV NACs may play roles in maintaining water status under drought or salt conditions, as well as water and metabolites conduction and translocation toward fruit. In contrast, rapid and negative responses of most of the ClNACs to low-temperature adversity may be related to the sensitivity to cold stress. Crosstalks among these abiotic stresses and hormone (abscisic acid and jasmonic acid) pathways were also discussed based on the expression of ClNAC genes. Our results will provide useful insights for the functional mining of NAC family in watermelon, as well as into the mechanisms underlying abiotic tolerance in other cash crops. PMID:27491393

  18. Crepuscular Flight Activity of an Invasive Insect Governed by Interacting Abiotic Factors

    PubMed Central

    Chen, Yigen; Seybold, Steven J.

    2014-01-01

    Seasonal and diurnal flight patterns of the invasive walnut twig beetle, Pityophthorus juglandis, were assessed between 2011 and 2014 in northern California, USA in the context of the effects of ambient temperature, light intensity, wind speed, and barometric pressure. Pityophthorus juglandis generally initiated flight in late January and continued until late November. This seasonal flight could be divided approximately into three phases (emergence: January–March; primary flight: May–July; and secondary flight: September–October). The seasonal flight response to the male-produced aggregation pheromone was consistently female-biased (mean of 58.9% females). Diurnal flight followed a bimodal pattern with a minor peak in mid-morning and a major peak at dusk (76.4% caught between 1800 and 2200 h). The primarily crepuscular flight activity had a Gaussian relationship with ambient temperature and barometric pressure but a negative exponential relationship with increasing light intensity and wind speed. A model selection procedure indicated that the four abiotic factors collectively and interactively governed P. juglandis diurnal flight. For both sexes, flight peaked under the following second-order interactions among the factors when: 1) temperature between was 25 and 30°C and light intensity was less than 2000 lux; 2) temperature was between 25 and 35°C and barometric pressure was between 752 and 762 mba (and declined otherwise); 3) barometric pressure was between 755 and 761 mba and light intensity was less than 2000 lux (and declined otherwise); and 4) temperature was ca. 30°C and wind speed was ca. 2 km/h. Thus, crepuscular flight activity of this insect can be best explained by the coincidence of moderately high temperature, low light intensity, moderate wind speed, and low to moderate barometric pressure. The new knowledge provides physical and temporal guidelines for the application of semiochemical-based control techniques as part of an IPM program for

  19. Crepuscular flight activity of an invasive insect governed by interacting abiotic factors.

    PubMed

    Chen, Yigen; Seybold, Steven J

    2014-01-01

    Seasonal and diurnal flight patterns of the invasive walnut twig beetle, Pityophthorus juglandis, were assessed between 2011 and 2014 in northern California, USA in the context of the effects of ambient temperature, light intensity, wind speed, and barometric pressure. Pityophthorus juglandis generally initiated flight in late January and continued until late November. This seasonal flight could be divided approximately into three phases (emergence: January-March; primary flight: May-July; and secondary flight: September-October). The seasonal flight response to the male-produced aggregation pheromone was consistently female-biased (mean of 58.9% females). Diurnal flight followed a bimodal pattern with a minor peak in mid-morning and a major peak at dusk (76.4% caught between 1800 and 2200 h). The primarily crepuscular flight activity had a Gaussian relationship with ambient temperature and barometric pressure but a negative exponential relationship with increasing light intensity and wind speed. A model selection procedure indicated that the four abiotic factors collectively and interactively governed P. juglandis diurnal flight. For both sexes, flight peaked under the following second-order interactions among the factors when: 1) temperature between was 25 and 30 °C and light intensity was less than 2000 lux; 2) temperature was between 25 and 35 °C and barometric pressure was between 752 and 762 mba (and declined otherwise); 3) barometric pressure was between 755 and 761 mba and light intensity was less than 2000 lux (and declined otherwise); and 4) temperature was ca. 30 °C and wind speed was ca. 2 km/h. Thus, crepuscular flight activity of this insect can be best explained by the coincidence of moderately high temperature, low light intensity, moderate wind speed, and low to moderate barometric pressure. The new knowledge provides physical and temporal guidelines for the application of semiochemical-based control techniques as part of an IPM program for this

  20. Abiotic factors in colony formation: effects of nutrition and light on extracellular polysaccharide production and cell aggregates of Microcystis aeruginosa

    NASA Astrophysics Data System (ADS)

    Yang, Zhen; Kong, Fanxiang

    2013-07-01

    Colony morphology is important for Microcystis to sustain a competitive advantage in eutrophic lakes. The mechanism of colony formation in Microcystis is currently unclear. Extracellular polysaccharide (EPS) has been reported to play an important role in cell aggregate formation of some phytoplankton. Microcystis aeruginosa was cultivated under varied abiotic conditions, including different nutrient, light, and temperature conditions, to investigate their effects on EPS production and morphological change. The results show that nutrient concentration and light intensity have great effects on EPS productionin M. aeruginosa. There was a considerable increase in EPS production after M. aeruginosa was cultivated in adjusted culture conditions similar to those present in the field (28.9 mg C/L, 1.98 mg N/L, 0.65 mg P/L, light intensity: 100 μmol/(m2 · s)). These results indicate that abiotic factors might be one of the triggers for colony formation in Microcystis.

  1. The Effect of Abiotic Factors on Marine Animal Body Size Evolution

    NASA Astrophysics Data System (ADS)

    Wang, X. F.; Wong, W.; Heim, N.; Payne, J.

    2015-12-01

    While there is evidence of a general increase in body size over time, there has been no comprehensive attempt to determine the influence of abiotic factors on body size. Although an increase in maximum body size has been observed during and after the Precambrian oxidation events in the Late Archean and at the onset of the Cambrian, these observations took into account the appearance of eukaryotic life and multicellular life respectively. Using a database of marine animal body sizes spanning the Phanerozoic, we conducted a series of Pearson product-moment correlation tests with igneous rock weathering (Strontium-87: Strontium-86), rate of carbon cycle (δ13C), temperature (δ18O), CO2 concentration, sulfate mineral weathering (δ34S), atmospheric oxygen concentration, and sea level as independent variables, and mean body size as the dependent variable. Our test yielded a correlation coefficient of 0.81 between δ18O and body size, and -0.78 between rCO2 and body size; since δ18O is inversely correlated with temperature, these results indicate that both temperature and CO2 have strong inverse relationships with body size. Atmospheric oxygen yielded a correlation coefficient of 0.09, demonstrating that it ceased to play an influential role in shaping body sizes following the start of the Phanerozoic.

  2. Biotic-Abiotic Interactions: Factors that Influence Peptide-Graphene Interactions.

    PubMed

    Kim, Steve S; Kuang, Zhifeng; Ngo, Yen H; Farmer, Barry L; Naik, Rajesh R

    2015-09-16

    Understanding the factors that influence the interaction between biomolecules and abiotic surfaces is of utmost interest in biosensing and biomedical research. Through phage display technology, several peptides have been identified as specific binders to abiotic material surfaces, such as gold, graphene, silver, and so forth. Using graphene-peptide as our model abiotic-biotic pair, we investigate the effect of graphene quality, number of layers, and the underlying support substrate effect on graphene-peptide interactions using both experiments and computation. Our results indicate that graphene quality plays a significant role in graphene-peptide interactions. The graphene-biomolecule interaction appears to show no significant dependency on the number of graphene layers or the underlying support substrate. PMID:26305504

  3. Abiotic factors affecting summer distribution and movement of male paddlefish, Polyodon spathula, in a prairie reservoir

    USGS Publications Warehouse

    Paukert, C.P.; Fisher, W.L.

    2000-01-01

    Six male paddlefish, Polyodon spathula, were implanted with ultrasonic temperature-sensing transmitters and tracked during June through August 1997 to quantify effects of physicochemical conditions on their distribution and movement in Keystone Reservoir, Oklahoma. Paddlefish moved about twice as much during night than day. Movement rate of paddlefish was related to reservoir water level, inflow, and discharge from the reservoir at night; however, none of these variables was significant during the day. Location in the reservoir (distance from the dam) was negatively related to water level and positively related to inflow during day and night periods. Location in the reservoir was negatively related to discharge during the day. Paddlefish avoided the highest available water temperatures, but did not always avoid low dissolved oxygen concentrations. Paddlefish avoided the Cimarron River arm of the reservoir in summer, possibly because of high salinity. Our study demonstrates that distribution of paddlefish during summer and movement in Keystone Reservoir was influenced by physicochemical and hydrologic conditions in the system. However, biotic factors (e.g., food availability) not measured in this study may have been influenced by abiotic conditions in the reservoir.

  4. Comprehensive Analysis Suggests Overlapping Expression of Rice ONAC Transcription Factors in Abiotic and Biotic Stress Responses

    PubMed Central

    Sun, Lijun; Huang, Lei; Hong, Yongbo; Zhang, Huijuan; Song, Fengming; Li, Dayong

    2015-01-01

    NAC (NAM/ATAF/CUC) transcription factors comprise a large plant-specific gene family that contains more than 149 members in rice. Extensive studies have revealed that NAC transcription factors not only play important roles in plant growth and development, but also have functions in regulation of responses to biotic and abiotic stresses. However, biological functions for most of the members in the NAC family remain unknown. In this study, microarray data analyses revealed that a total of 63 ONAC genes exhibited overlapping expression patterns in rice under various abiotic (salt, drought, and cold) and biotic (infection by fungal, bacterial, viral pathogens, and parasitic plants) stresses. Thirty-eight ONAC genes exhibited overlapping expression in response to any two abiotic stresses, among which 16 of 30 selected ONAC genes were upregulated in response to exogenous ABA. Sixty-five ONAC genes showed overlapping expression patterns in response to any two biotic stresses. Results from the present study suggested that members of the ONAC genes with overlapping expression pattern may have pleiotropic biological functions in regulation of defense response against different abiotic and biotic stresses, which provide clues for further functional analysis of the ONAC genes in stress tolerance and pathogen resistance. PMID:25690040

  5. Mercury bioaccumulation in an estuarine predator: Biotic factors, abiotic factors, and assessments of fish health.

    PubMed

    Smylie, Meredith S; McDonough, Christopher J; Reed, Lou Ann; Shervette, Virginia R

    2016-07-01

    Estuarine wetlands are major contributors to mercury (Hg) transformation into its more toxic form, methylmercury (MeHg). Although these complex habitats are important, estuarine Hg bioaccumulation is not well understood. The longnose gar Lepisosteus osseus (L. 1758), an estuarine predator in the eastern United States, was selected to examine Hg processes due to its abundance, estuarine residence, and top predator status. This study examined variability in Hg concentrations within longnose gar muscle tissue spatially and temporally, the influence of biological factors, potential maternal transfer, and potential negative health effects on these fish. Smaller, immature fish had the highest Hg concentrations and were predominantly located in low salinity waters. Sex and diet were also important factors and Hg levels peaked in the spring. Although maternal transfer occurred in small amounts, the potential negative health effects to young gar remain unknown. Fish health as measured by fecundity and growth rate appeared to be relatively unaffected by Hg at concentrations in the present study (less than 1.3 ppm wet weight). The analysis of biotic and abiotic factors relative to tissue Hg concentrations in a single estuarine fish species provided valuable insight in Hg bioaccumulation, biomagnification, and elimination. Insights such as these can improve public health policy and environmental management decisions related to Hg pollution. PMID:27086072

  6. Abiotic Factors Shape Microbial Diversity in Sonoran Desert Soils

    PubMed Central

    Fitak, Robert R.; Munguia-Vega, Adrian; Racolta, Adriana; Martinson, Vincent G.; Dontsova, Katerina

    2012-01-01

    High-throughput, culture-independent surveys of bacterial and archaeal communities in soil have illuminated the importance of both edaphic and biotic influences on microbial diversity, yet few studies compare the relative importance of these factors. Here, we employ multiplexed pyrosequencing of the 16S rRNA gene to examine soil- and cactus-associated rhizosphere microbial communities of the Sonoran Desert and the artificial desert biome of the Biosphere2 research facility. The results of our replicate sampling approach show that microbial communities are shaped primarily by soil characteristics associated with geographic locations, while rhizosphere associations are secondary factors. We found little difference between rhizosphere communities of the ecologically similar saguaro (Carnegiea gigantea) and cardón (Pachycereus pringlei) cacti. Both rhizosphere and soil communities were dominated by the disproportionately abundant Crenarchaeota class Thermoprotei, which comprised 18.7% of 183,320 total pyrosequencing reads from a comparatively small number (1,337 or 3.7%) of the 36,162 total operational taxonomic units (OTUs). OTUs common to both soil and rhizosphere samples comprised the bulk of raw sequence reads, suggesting that the shared community of soil and rhizosphere microbes constitute common and abundant taxa, particularly in the bacterial phyla Proteobacteria, Actinobacteria, Planctomycetes, Firmicutes, Bacteroidetes, Chloroflexi, and Acidobacteria. The vast majority of OTUs, however, were rare and unique to either soil or rhizosphere communities and differed among locations dozens of kilometers apart. Several soil properties, particularly soil pH and carbon content, were significantly correlated with community diversity measurements. Our results highlight the importance of culture-independent approaches in surveying microbial communities of extreme environments. PMID:22885757

  7. Abiotic factors shape microbial diversity in Sonoran Desert soils.

    PubMed

    Andrew, David R; Fitak, Robert R; Munguia-Vega, Adrian; Racolta, Adriana; Martinson, Vincent G; Dontsova, Katerina

    2012-11-01

    High-throughput, culture-independent surveys of bacterial and archaeal communities in soil have illuminated the importance of both edaphic and biotic influences on microbial diversity, yet few studies compare the relative importance of these factors. Here, we employ multiplexed pyrosequencing of the 16S rRNA gene to examine soil- and cactus-associated rhizosphere microbial communities of the Sonoran Desert and the artificial desert biome of the Biosphere2 research facility. The results of our replicate sampling approach show that microbial communities are shaped primarily by soil characteristics associated with geographic locations, while rhizosphere associations are secondary factors. We found little difference between rhizosphere communities of the ecologically similar saguaro (Carnegiea gigantea) and cardón (Pachycereus pringlei) cacti. Both rhizosphere and soil communities were dominated by the disproportionately abundant Crenarchaeota class Thermoprotei, which comprised 18.7% of 183,320 total pyrosequencing reads from a comparatively small number (1,337 or 3.7%) of the 36,162 total operational taxonomic units (OTUs). OTUs common to both soil and rhizosphere samples comprised the bulk of raw sequence reads, suggesting that the shared community of soil and rhizosphere microbes constitute common and abundant taxa, particularly in the bacterial phyla Proteobacteria, Actinobacteria, Planctomycetes, Firmicutes, Bacteroidetes, Chloroflexi, and Acidobacteria. The vast majority of OTUs, however, were rare and unique to either soil or rhizosphere communities and differed among locations dozens of kilometers apart. Several soil properties, particularly soil pH and carbon content, were significantly correlated with community diversity measurements. Our results highlight the importance of culture-independent approaches in surveying microbial communities of extreme environments. PMID:22885757

  8. Abiotic and Biotic Factors Affecting Resting Spore Formation in the Mite Pathogen Neozygites floridana

    PubMed Central

    da Silveira Duarte, Vanessa; Westrum, Karin; Lopes Ribeiro, Ana Elizabete; Guedes Corrêa Gondim Junior, Manoel; Klingen, Ingeborg; Delalibera Júnior, Italo

    2013-01-01

    Neozygites floridana is an obligate mite pathogenic fungus in the Entomophthoromycota. It has been suggested that resting spores of this fungus are produced as a strategy to survive adverse conditions. In the present study, possible mechanisms involved in the regulation of resting spore formation were investigated in the hosts Tetranychus urticae and Tetranychus evansi. Abiotic and biotic factors mimicking conditions that we, based on earlier field studies, thought might induce resting spores in temperate and tropical regions were tested with isolates from Norway and Brazil. A total of 42 combinations of conditions were tested, but only one induced the formation of a high number of resting spores in only one isolate. The Brazilian isolate ESALQ1420 produced a large number of resting spores (51.5%) in T. urticae at a temperature of 11°C, photoperiod of 10L:14D, and light intensity of 42–46 (μmol m−2 s−1) on nonsenescent plants (nondiapausing females). Resting spores of the Brazilian N. floridana isolate ESALQ1421 were found at very low levels (up to 1.0%). Small percentages of T. urticae with resting spores (0–5.0%) were found for the Norwegian isolate NCRI271/04 under the conditions tested. The percentages of resting spores found for the Norwegian isolate in our laboratory studies are similar to the prevalence reported in earlier field studies. PMID:23878542

  9. A wheat salinity-induced WRKY transcription factor TaWRKY93 confers multiple abiotic stress tolerance in Arabidopsis thaliana.

    PubMed

    Qin, Yuxiang; Tian, Yanchen; Liu, Xiuzhi

    2015-08-21

    Wheat is an important crop in the world. But most of the cultivars are salt sensitive, and often adversely affected by salt stress. WRKY transcription factors play a major role in plant responses to salt stress, but the effective salinity regulatory WRKYs identified in bread wheat are limited and the mechanism of salt stress tolerance is also not well explored. Here, we identified a salt (NaCl) induced class II WRKY transcription factor TaWRKY93. Its transcript level was strongly induced by salt (NaCl) and exogenous abscisic acid (ABA). Over-expression of TaWRKY93 in Arabidopsis thaliana enhanced salt (NaCl), drought, low temperature and osmotic (mannitol) stress tolerance, mainly demonstrated by transgenic plants forming longer primary roots or more lateral roots on MS plates supplemented with NaCl and mannitol individually, higher survival rate under drought and low temperature stress. Further, transgenic plants maintained a more proline content, higher relative water content and less electrolyte leakage than the wild type plants. The transcript abundance of a series of abiotic stress-related genes was up-regulated in the TaWRKY93 transgenic plants. In summary, TaWRKY93 is a new positive regulator of abiotic stress, it may increase salinity, drought and low temperature stress tolerance through enhancing osmotic adjustment, maintaining membrane stability and increasing transcription of stress related genes, and contribute to the superior agricultural traits of SR3 through promoting root development. It can be used as a candidate gene for wheat transgenic engineering breeding against abiotic stress. PMID:26106823

  10. Influence of Various Levels of Iron and Other Abiotic Factors on Siderophorogenesis in Paddy Field Cyanobacterium Anabaena oryzae.

    PubMed

    Singh, Anumeha; Mishra, Arun Kumar

    2015-05-01

    Siderophore production in Anabaena oryzae was investigated under the influence of various levels of iron and other abiotic factors such as pH, temperature, light and different nitrogen sources. Optimization of culture conditions under controlled mechanisms of these abiotic factors lead to the siderophore production in significant amount. Under iron-starved condition, A. oryzae extracellularly releases 89.17% hydroxymate-type siderophore. Slightly alkaline pH and 30 °C temperature was found stimulatory for the cyanobacterial growth and siderophorogenesis (88.52% SU and 83.87% SU, respectively). Excess iron loading had a negative impact on siderophore production along with the alterations in the morphology and growth. Further, scanning electron microphotographs signified that higher concentrations of iron lead to complete damage of the cells and alterations in membrane proteins possibly transporters responsible for exchange of siderophore complex from environment to the cell. SDS-PAGE analysis of whole cell proteins showed overexpression of low molecular weight proteins ranges between 20.1 to 29.0 kDa up to 100-μM iron concentrations. These polypeptides/proteins might be involved in maintaining iron homeostasis by regulating siderophore production. Results suggest that lower concentrations of iron ≤ 50 μM along with other abiotic factors are stimulatory, whereas higher concentrations (>50 μM) are toxic. Data further suggested that cyanobacterium A. oryzae can serve as a potential biofertilizer especially in iron-rich soil through sequestration by the power of natural Fe(III)-siderophore complex formation. PMID:25805017

  11. Impact of abiotic factor changes in blowfly, Achoetandrus rufifacies (Diptera: Calliphoridae), in northern Thailand.

    PubMed

    Klong-Klaew, Tunwadee; Sukontason, Kom; Ngoen-klan, Ratchadawan; Moophayak, Kittikhun; Irvine, Kim N; Kurahashi, Hiromu; Prangkio, Chira; Sanit, Sangob; Sukontason, Kabkaew L

    2014-04-01

    Understanding how medically important flies respond to abiotic factor changes is necessary for predicting their population dynamics. In this study, we investigated the geographical distribution of the medically important blowfly, Achoetandrus rufifacies (Macquart) (Diptera: Calliphoridae), and ascertained the response to climatic and physio-environmental factors in Chiang Mai, northern Thailand. Adult fly surveys were carried out every 2 weeks from May 2009 to May 2010 at 18 systematically randomized study sites in three districts of Chiang Mai province (Mueang Chiang Mai, Mae Rim, and Hang Dong), using reconstructable funnel traps with 1-day tainted beef offal as bait. During the study period, 8,861 adult A. rufifacies were captured, with peak densities being observed at the end of winter (i.e., late February) and throughout most of the summer (May to March). Population density had a weak but significant (α = 0.05) positive correlation with temperature (r = 0.329) and light intensity (r = 0.231), and a weak but significant (α = 0.05) negative correlation with relative humidity (r = -0.236). From the six ecological land use types (disturbed mixed deciduous forest, mixed deciduous forest, mixed orchard, lowland village, city town, and paddy field), greater fly densities were observed generally in the disturbed mixed deciduous forest and lowland village, but not in the paddy fields. In conclusion, A. rufifacies are abundant from the end of winter and throughout most of the summer in northern Thailand, with population density being weakly positively correlated with temperature and light intensity, but weakly negatively correlated with relative humidity. The greatest densities of this fly species were collected in disturbed mixed deciduous forest and lowland village land uses. The prediction of annual and season specific distributions of A. rufifacies were provided in each season and all-year patterns using a co-kriging approach (ArcGIS9.2). PMID:24535731

  12. Abiotic Factors Affecting the Persistence of Avian Influenza Virus in Surface Waters of Waterfowl Habitats

    PubMed Central

    Dalton, Melinda S.; Cressler, Alan M.; Berghaus, Roy D.; Stallknecht, David E.

    2014-01-01

    Avian influenza (AI) virus can remain infectious in water for months, and virus-contaminated surface water is considered to be a source of infection within wild waterfowl populations. Previous work has characterized the effects of pH, salinity, and temperature on viral persistence in water, but most of that work was done with modified distilled water. The objective of this study was to identify the abiotic factors that influence the duration of AI virus persistence in natural surface water. Surface water samples were collected from 38 waterfowl habitats distributed across the United States. Samples were submitted to the U.S. Geological Survey National Water Quality Laboratory for chemical analysis and the University of Georgia for viral reduction time analysis. Samples were filtered with 0.22-μm filters, and the durations of persistence of three wild-bird-derived influenza A viruses within each water sample at 10, 17, and 28°C were determined. The effects of the surface water physicochemical factors on the duration of AI viral persistence in laboratory experiments were evaluated by multivariable linear regression with robust standard errors. The duration of AI virus persistence was determined to be longest in filtered surface water with a low temperature (<17°C), a neutral-to-basic pH (7.0 to 8.5), low salinity (<0.5 ppt), and a low ammonia concentration (<0.5 mg/liter). Our results also highlighted potential strain-related variation in the stability of AI virus in surface water. These results bring us closer to being able to predict the duration of AI virus persistence in surface water of waterfowl habitats. PMID:24584247

  13. Surface chemistry allows for abiotic precipitation of dolomite at low temperature

    NASA Astrophysics Data System (ADS)

    Roberts, Jennifer A.; Kenward, Paul A.; Fowle, David A.; Goldstein, Robert H.; González, Luis A.; Moore, David S.

    2013-09-01

    Although the mineral dolomite is abundant in ancient low-temperature sedimentary systems, it is scarce in modern systems below 50 °C. Chemical mechanism(s) enhancing its formation remain an enigma because abiotic dolomite has been challenging to synthesize at low temperature in laboratory settings. Microbial enhancement of dolomite precipitation at low temperature has been reported; however, it is still unclear exactly how microorganisms influence reaction kinetics. Here we document the abiotic synthesis of low-temperature dolomite in laboratory experiments and constrain possible mechanisms for dolomite formation. Ancient and modern seawater solution compositions, with identical pH and pCO2, were used to precipitate an ordered, stoichiometric dolomite phase at 30 °C in as few as 20 d. Mg-rich phases nucleate exclusively on carboxylated polystyrene spheres along with calcite, whereas aragonite forms in solution via homogeneous nucleation. We infer that Mg ions are complexed and dewatered by surface-bound carboxyl groups, thus decreasing the energy required for carbonation. These results indicate that natural surfaces, including organic matter and microbial biomass, possessing a high density of carboxyl groups may be a mechanism by which ordered dolomite nuclei form. Although environments rich in organic matter may be of interest, our data suggest that sharp biogeochemical interfaces that promote microbial death, as well as those with high salinity may, in part, control carboxyl-group density on organic carbon surfaces, consistent with origin of dolomites from microbial biofilms, as well as hypersaline and mixing zone environments.

  14. Abiotic factors influencing biomass accumulation of green tide causing Ulva spp. on Pyropia culture rafts in the Yellow Sea, China.

    PubMed

    Keesing, John K; Liu, Dongyan; Shi, Yajun; Wang, Yujue

    2016-04-15

    Annually recurrent green-tides in the Yellow Sea have been shown to result from direct disposal into the sea of fouling Ulva from Pyropia aquaculture. The role abiotic factors play in Ulva biomass accumulation on rafts was studied to find ways to mitigate this problem. Dissolved inorganic nitrogen (DIN) was very high at all sites, but the highest Ulva biomass was associated with the lowest DIN and anthropogenic N. Under luxuriant background nutrient conditions, variability in temperature and periods of emersion, rather than pH, light and salinity determined Ulva biomass. Two dominant species of Ulva displayed differing tolerances to temperature and desiccation which helped explain why Ulva prolifera dominates floating green-tides. Rather than trying to mitigate green-tides only by reducing nutrient pollution, an earlier harvest of Pyropia in southern Jiangsu Province especially before temperatures increase greatly above 10°C during April, could reduce the biomass of U. prolifera disposed from rafts. PMID:26936121

  15. ABI-like transcription factor gene TaABL1 from wheat improves multiple abiotic stress tolerances in transgenic plants.

    PubMed

    Xu, Dong-Bei; Gao, Shi-Qing; Ma, You-Zhi; Xu, Zhao-Shi; Zhao, Chang-Ping; Tang, Yi-Miao; Li, Xue-Yin; Li, Lian-Cheng; Chen, Yao-Feng; Chen, Ming

    2014-12-01

    The phytohormone abscisic acid (ABA) plays crucial roles in adaptive responses of plants to abiotic stresses. ABA-responsive element binding proteins (AREBs) are basic leucine zipper transcription factors that regulate the expression of downstream genes containing ABA-responsive elements (ABREs) in promoter regions. A novel ABI-like (ABA-insensitive) transcription factor gene, named TaABL1, containing a conserved basic leucine zipper (bZIP) domain was cloned from wheat. Southern blotting showed that three copies were present in the wheat genome. Phylogenetic analyses indicated that TaABL1 belonged to the AREB subfamily of the bZIP transcription factor family and was most closely related to ZmABI5 in maize and OsAREB2 in rice. Expression of TaABL1 was highly induced in wheat roots, stems, and leaves by ABA, drought, high salt, and low temperature stresses. TaABL1 was localized inside the nuclei of transformed wheat mesophyll protoplast. Overexpression of TaABL1 enhanced responses of transgenic plants to ABA and hastened stomatal closure under stress, thereby improving tolerance to multiple abiotic stresses. Furthermore, overexpression of TaABL1 upregulated or downregulated the expression of some stress-related genes controlling stomatal closure in transgenic plants under ABA and drought stress conditions, suggesting that TaABL1 might be a valuable genetic resource for transgenic molecular breeding. PMID:25344442

  16. Evaluating reaction pathways of hydrothermal abiotic organic synthesis at elevated temperatures and pressures using carbon isotopes

    NASA Astrophysics Data System (ADS)

    Fu, Qi; Socki, Richard A.; Niles, Paul B.

    2015-04-01

    Experiments were performed to better understand the role of environmental factors on reaction pathways and corresponding carbon isotope fractionations during abiotic hydrothermal synthesis of organic compounds using piston cylinder apparatus at 750 °C and 5.5 kbars. Chemical compositions of experimental products and corresponding carbon isotopic values were obtained by a Pyrolysis-GC-MS-IRMS system. Alkanes (methane and ethane), straight-chain saturated alcohols (ethanol and n-butanol) and monocarboxylic acids (formic and acetic acids) were generated with ethanol being the only organic compound with higher δ13C than CO2. CO was not detected in experimental products owing to the favorable water-gas shift reaction under high water pressure conditions. The pattern of δ13C values of CO2, carboxylic acids and alkanes are consistent with their equilibrium isotope relationships: CO2 > carboxylic acids > alkanes, but the magnitude of the fractionation among them is higher than predicted isotope equilibrium values. In particular, the isotopic fractionation between CO2 and CH4 remained constant at ∼31‰, indicating a kinetic effect during CO2 reduction processes. No "isotope reversal" of δ13C values for alkanes or carboxylic acids was observed, which indicates a different reaction pathway than what is typically observed during Fischer-Tropsch synthesis under gas phase conditions. Under constraints imposed in experiments, the anomalous 13C isotope enrichment in ethanol suggests that hydroxymethylene is the organic intermediate, and that the generation of other organic compounds enriched in 12C were facilitated by subsequent Rayleigh fractionation of hydroxymethylene reacting with H2 and/or H2O. Carbon isotope fractionation data obtained in this study are instrumental in assessing the controlling factors on abiotic formation of organic compounds in hydrothermal systems. Knowledge on how environmental conditions affect reaction pathways of abiotic synthesis of organic

  17. NAC transcription factors in plant multiple abiotic stress responses: progress and prospects

    PubMed Central

    Shao, Hongbo; Wang, Hongyan; Tang, Xiaoli

    2015-01-01

    Abiotic stresses adversely affect plant growth and agricultural productivity. According to the current climate prediction models, crop plants will face a greater number of environmental stresses, which are likely to occur simultaneously in the future. So it is very urgent to breed broad-spectrum tolerant crops in order to meet an increasing demand for food productivity due to global population increase. As one of the largest families of transcription factors (TFs) in plants, NAC TFs play vital roles in regulating plant growth and development processes including abiotic stress responses. Lots of studies indicated that many stress-responsive NAC TFs had been used to improve stress tolerance in crop plants by genetic engineering. In this review, the recent progress in NAC TFs was summarized, and the potential utilization of NAC TFs in breeding abiotic stress tolerant transgenic crops was also be discussed. In view of the complexity of field conditions and the specificity in multiple stress responses, we suggest that the NAC TFs commonly induced by multiple stresses should be promising candidates to produce plants with enhanced multiple stress tolerance. Furthermore, the field evaluation of transgenic crops harboring NAC genes, as well as the suitable promoters for minimizing the negative effects caused by over-expressing some NAC genes, should be considered. PMID:26579152

  18. Recent Advances in Utilizing Transcription Factors to Improve Plant Abiotic Stress Tolerance by Transgenic Technology

    PubMed Central

    Wang, Hongyan; Wang, Honglei; Shao, Hongbo; Tang, Xiaoli

    2016-01-01

    Agricultural production and quality are adversely affected by various abiotic stresses worldwide and this will be exacerbated by the deterioration of global climate. To feed a growing world population, it is very urgent to breed stress-tolerant crops with higher yields and improved qualities against multiple environmental stresses. Since conventional breeding approaches had marginal success due to the complexity of stress tolerance traits, the transgenic approach is now being popularly used to breed stress-tolerant crops. So identifying and characterizing the critical genes involved in plant stress responses is an essential prerequisite for engineering stress-tolerant crops. Far beyond the manipulation of single functional gene, engineering certain regulatory genes has emerged as an effective strategy now for controlling the expression of many stress-responsive genes. Transcription factors (TFs) are good candidates for genetic engineering to breed stress-tolerant crop because of their role as master regulators of many stress-responsive genes. Many TFs belonging to families AP2/EREBP, MYB, WRKY, NAC, bZIP have been found to be involved in various abiotic stresses and some TF genes have also been engineered to improve stress tolerance in model and crop plants. In this review, we take five large families of TFs as examples and review the recent progress of TFs involved in plant abiotic stress responses and their potential utilization to improve multiple stress tolerance of crops in the field conditions. PMID:26904044

  19. Invasion biology in non-free-living species: interactions between abiotic (climatic) and biotic (host availability) factors in geographical space in crayfish commensals (Ostracoda, Entocytheridae)

    PubMed Central

    Mestre, Alexandre; Aguilar-Alberola, Josep A; Baldry, David; Balkis, Husamettin; Ellis, Adam; Gil-Delgado, Jose A; Grabow, Karsten; Klobučar, Göran; Kouba, Antonín; Maguire, Ivana; Martens, Andreas; Mülayim, Ayşegül; Rueda, Juan; Scharf, Burkhard; Soes, Menno; S Monrós, Juan; Mesquita-Joanes, Francesc

    2013-01-01

    In invasion processes, both abiotic and biotic factors are considered essential, but the latter are usually disregarded when modeling the potential spread of exotic species. In the framework of set theory, interactions between biotic (B), abiotic (A), and movement-related (M) factors in the geographical space can be hypothesized with BAM diagrams and tested using ecological niche models (ENMs) to estimate A and B areas. The main aim of our survey was to evaluate the interactions between abiotic (climatic) and biotic (host availability) factors in geographical space for exotic symbionts (i.e., non-free-living species), using ENM techniques combined with a BAM framework and using exotic Entocytheridae (Ostracoda) found in Europe as model organisms. We carried out an extensive survey to evaluate the distribution of entocytherids hosted by crayfish in Europe by checking 94 European localities and 12 crayfish species. Both exotic entocytherid species found, Ankylocythere sinuosa and Uncinocythere occidentalis, were widely distributed in W Europe living on the exotic crayfish species Procambarus clarkii and Pacifastacus leniusculus, respectively. No entocytherids were observed in the remaining crayfish species. The suitable area for A. sinuosa was mainly restricted by its own limitations to minimum temperatures in W and N Europe and precipitation seasonality in circum-Mediterranean areas. Uncinocythere occidentalis was mostly restricted by host availability in circum-Mediterranean regions due to limitations of P. leniusculus to higher precipitation seasonality and maximum temperatures. The combination of ENMs with set theory allows studying the invasive biology of symbionts and provides clues about biogeographic barriers due to abiotic or biotic factors limiting the expansion of the symbiont in different regions of the invasive range. The relative importance of abiotic and biotic factors on geographical space can then be assessed and applied in conservation plans. This

  20. Molecular characterization of BZR transcription factor family and abiotic stress induced expression profiling in Brassica rapa.

    PubMed

    Saha, Gopal; Park, Jong-In; Jung, Hee-Jeong; Ahmed, Nasar Uddin; Kayum, Md Abdul; Kang, Jong-Goo; Nou, Ill-Sup

    2015-07-01

    BRASSINAZOLE-RESISTANT (BZR) transcription factors (TFs) are primarily well known as positive regulators of Brassinosteroid (BR) signal transduction in different plants. BR is a plant specific steroid hormone, which has multiple stress resistance functions besides various growth regulatory roles. Being an important regulator of the BR synthesis, BZR TFs might have stress resistance related activities. However, no stress resistance related functional study of BZR TFs has been reported in any crop plants so far. Therefore, this study identified 15 BZR TFs of Brassica rapa (BrBZR) from a genome-wide survey and characterized them through sequence analysis and expression profiling against several abiotic stresses. Various systematic in silico analysis of these TFs validated the fundamental properties of BZRs, where a high degree of similarity also observed with recognized BZRs of other plant species from the comparison studies. In the organ specific expression analyses, 6 BrBZR TFs constitutively expressed in flower developmental stages indicating their flower specific functions. Subsequently, from the stress resistance related expression profiles differential transcript abundance levels were observed by 6 and 11 BrBZRs against salt and drought stresses, respectively. All BrBZRs showed several folds up-regulation against exogenous ABA treatment. All BrBZRs also showed differential expression against low temperature stress treatments and these TFs were proposed as transcriptional activators of CBF cold response pathway of B. rapa. Notably, three BrBZRs gave co-responsive expression against all the stresses tested here, suggesting their multiple stress resistance related functions. Thus, the findings would be helpful in resolving the complex regulatory mechanism of BZRs in stress resistance and further functional genomics study of these potential TFs in different Brassica crops. PMID:25931321

  1. Microbial Hub Taxa Link Host and Abiotic Factors to Plant Microbiome Variation.

    PubMed

    Agler, Matthew T; Ruhe, Jonas; Kroll, Samuel; Morhenn, Constanze; Kim, Sang-Tae; Weigel, Detlef; Kemen, Eric M

    2016-01-01

    Plant-associated microorganisms have been shown to critically affect host physiology and performance, suggesting that evolution and ecology of plants and animals can only be understood in a holobiont (host and its associated organisms) context. Host-associated microbial community structures are affected by abiotic and host factors, and increased attention is given to the role of the microbiome in interactions such as pathogen inhibition. However, little is known about how these factors act on the microbial community, and especially what role microbe-microbe interaction dynamics play. We have begun to address this knowledge gap for phyllosphere microbiomes of plants by simultaneously studying three major groups of Arabidopsis thaliana symbionts (bacteria, fungi and oomycetes) using a systems biology approach. We evaluated multiple potential factors of microbial community control: we sampled various wild A. thaliana populations at different times, performed field plantings with different host genotypes, and implemented successive host colonization experiments under lab conditions where abiotic factors, host genotype, and pathogen colonization was manipulated. Our results indicate that both abiotic factors and host genotype interact to affect plant colonization by all three groups of microbes. Considering microbe-microbe interactions, however, uncovered a network of interkingdom interactions with significant contributions to community structure. As in other scale-free networks, a small number of taxa, which we call microbial "hubs," are strongly interconnected and have a severe effect on communities. By documenting these microbe-microbe interactions, we uncover an important mechanism explaining how abiotic factors and host genotypic signatures control microbial communities. In short, they act directly on "hub" microbes, which, via microbe-microbe interactions, transmit the effects to the microbial community. We analyzed two "hub" microbes (the obligate biotrophic

  2. Microbial Hub Taxa Link Host and Abiotic Factors to Plant Microbiome Variation

    PubMed Central

    Agler, Matthew T.; Ruhe, Jonas; Kroll, Samuel; Morhenn, Constanze; Kim, Sang-Tae; Weigel, Detlef; Kemen, Eric M.

    2016-01-01

    Plant-associated microorganisms have been shown to critically affect host physiology and performance, suggesting that evolution and ecology of plants and animals can only be understood in a holobiont (host and its associated organisms) context. Host-associated microbial community structures are affected by abiotic and host factors, and increased attention is given to the role of the microbiome in interactions such as pathogen inhibition. However, little is known about how these factors act on the microbial community, and especially what role microbe–microbe interaction dynamics play. We have begun to address this knowledge gap for phyllosphere microbiomes of plants by simultaneously studying three major groups of Arabidopsis thaliana symbionts (bacteria, fungi and oomycetes) using a systems biology approach. We evaluated multiple potential factors of microbial community control: we sampled various wild A. thaliana populations at different times, performed field plantings with different host genotypes, and implemented successive host colonization experiments under lab conditions where abiotic factors, host genotype, and pathogen colonization was manipulated. Our results indicate that both abiotic factors and host genotype interact to affect plant colonization by all three groups of microbes. Considering microbe–microbe interactions, however, uncovered a network of interkingdom interactions with significant contributions to community structure. As in other scale-free networks, a small number of taxa, which we call microbial “hubs,” are strongly interconnected and have a severe effect on communities. By documenting these microbe–microbe interactions, we uncover an important mechanism explaining how abiotic factors and host genotypic signatures control microbial communities. In short, they act directly on “hub” microbes, which, via microbe–microbe interactions, transmit the effects to the microbial community. We analyzed two “hub” microbes (the

  3. Connecting RNA Processing to Abiotic Environmental Response in Arabidopsis: the role of a polyadenylation factor

    NASA Astrophysics Data System (ADS)

    Li, Q. Q.; Xu, R.; Hunt, A. G.; Falcone, D. L.

    Plants are constantly challenged by numerous environmental stresses both biotic and abiotic It is clear that plants have evolved to counter these stresses using all but limited means We recently discovered the potential role of a messenger RNA processing factor namely the Arabidopsis cleavage and polyadenylation specificity factor 30 kDa subunit AtCPSF30 when a mutant deficient in this factor displayed altered responses to an array of abiotic stresses This AtCPSF30 mutant named oxt6 exhibited an elevated tolerance to oxidative stress Microarray experiments of oxt6 and its complemented lines revealed an altered gene expression profile among which were antioxidative defense genes Interestingly the same gene encoding AtCPSF30 can also be transcribed into a large transcript that codes for a potential splicing factor Both protein products have a domain for RNA binding and a calmodulin binding domain activities of which have been confirmed by biochemical assays Surprisingly binding of AtCPSF30 to calmodulin inhibits the RNA-binding activity of the protein Mutational analysis shows that a small part of the protein is responsible for calmodulin binding and point mutations in this region abolished both RNA binding activity and the inhibition of this activity by calmodulin Analyses of the potential splicing factor are on going and the results will be presented The interesting possibilities for both the interplay between splicing and polyadenylation and the regulation of these processes by stimuli that act through

  4. Multiple NUCLEAR FACTOR Y transcription factors respond to abiotic stress in Brassica napus L.

    PubMed

    Xu, Li; Lin, Zhongyuan; Tao, Qing; Liang, Mingxiang; Zhao, Gengmao; Yin, Xiangzhen; Fu, Ruixin

    2014-01-01

    Members of the plant NUCLEAR FACTOR Y (NF-Y) family are composed of the NF-YA, NF-YB, and NF-YC subunits. In Brassica napus (canola), each of these subunits forms a multimember subfamily. Plant NF-Ys were reported to be involved in several abiotic stresses. In this study, we demonstrated that multiple members of thirty three BnNF-Ys responded rapidly to salinity, drought, or ABA treatments. Transcripts of five BnNF-YAs, seven BnNF-YBs, and two BnNF-YCs were up-regulated by salinity stress, whereas the expression of thirteen BnNF-YAs, ten BnNF-YBs, and four BnNF-YCs were induced by drought stress. Under NaCl treatments, the expression of one BnNF-YA10 and four NF-YBs (BnNF-YB3, BnNF-YB7, BnNF-YB10, and BnNF-YB14) were greatly increased. Under PEG treatments, the expression levels of four NF-YAs (BnNF-YA9, BnNF-YA10, BnNF-YA11, and BnNF-YA12) and five NF-YBs (BnNF-YB1, BnNF-YB8, BnNF-YB10, BnNF-YB13, and BnNF-YB14) were greatly induced. The expression profiles of 20 of the 27 salinity- or drought-induced BnNF-Ys were also affected by ABA treatment. The expression levels of six NF-YAs (BnNF-YA1, BnNF-YA7, BnNF-YA8, BnNF-YA9, BnNF-YA10, and BnNF-YA12) and seven BnNF-YB members (BnNF-YB2, BnNF-YB3, BnNF-YB7, BnNF-YB10, BnNF-YB11, BnNF-YB13, and BnNF-YB14) and two NF-YC members (BnNF-YC2 and BnNF-YC3) were greatly up-regulated by ABA treatments. Only a few BnNF-Ys were inhibited by the above three treatments. Several NF-Y subfamily members exhibited collinear expression patterns. The promoters of all stress-responsive BnNF-Ys harbored at least two types of stress-related cis-elements, such as ABRE, DRE, MYB, or MYC. The cis-element organization of BnNF-Ys was similar to that of Arabidopsis thaliana, and the promoter regions exhibited higher levels of nucleotide sequence identity with Brassica rapa than with Brassica oleracea. This work represents an entry point for investigating the roles of canola NF-Y proteins during abiotic stress responses and provides insight into

  5. Surface chemistry allows for abiotic precipitation of dolomite at low temperature

    PubMed Central

    Roberts, Jennifer A.; Kenward, Paul A.; Fowle, David A.; Goldstein, Robert H.; González, Luis A.; Moore, David S.

    2013-01-01

    Although the mineral dolomite is abundant in ancient low-temperature sedimentary systems, it is scarce in modern systems below 50 °C. Chemical mechanism(s) enhancing its formation remain an enigma because abiotic dolomite has been challenging to synthesize at low temperature in laboratory settings. Microbial enhancement of dolomite precipitation at low temperature has been reported; however, it is still unclear exactly how microorganisms influence reaction kinetics. Here we document the abiotic synthesis of low-temperature dolomite in laboratory experiments and constrain possible mechanisms for dolomite formation. Ancient and modern seawater solution compositions, with identical pH and pCO2, were used to precipitate an ordered, stoichiometric dolomite phase at 30 °C in as few as 20 d. Mg-rich phases nucleate exclusively on carboxylated polystyrene spheres along with calcite, whereas aragonite forms in solution via homogeneous nucleation. We infer that Mg ions are complexed and dewatered by surface-bound carboxyl groups, thus decreasing the energy required for carbonation. These results indicate that natural surfaces, including organic matter and microbial biomass, possessing a high density of carboxyl groups may be a mechanism by which ordered dolomite nuclei form. Although environments rich in organic matter may be of interest, our data suggest that sharp biogeochemical interfaces that promote microbial death, as well as those with high salinity may, in part, control carboxyl-group density on organic carbon surfaces, consistent with origin of dolomites from microbial biofilms, as well as hypersaline and mixing zone environments. PMID:23964124

  6. The soybean GmbZIP1 transcription factor enhances multiple abiotic stress tolerances in transgenic plants.

    PubMed

    Gao, Shi-Qing; Chen, Ming; Xu, Zhao-Shi; Zhao, Chang-Ping; Li, Liancheng; Xu, Hui-jun; Tang, Yi-miao; Zhao, Xin; Ma, You-Zhi

    2011-04-01

    Abscisic acid (ABA)-responsive element binding proteins (AREBs) are basic domain/leucine zipper transcription factors that bind to the ABA-responsive element (ABRE) in the promoter regions of ABA-inducible genes in plants. A novel bZIP transcription factor gene, GmbZIP1, encoding 438 amino acids with a conserved bZIP domain composed of 60 amino acids was isolated from salt-tolerant soybean cv. Tiefeng 8. Southern blotting showed that only one copy was present in the soybean genome. Phylogenetic analyses showed that GmbZIP1 belonged to the AREB subfamily of the bZIP family and was most closely related to AtABF2 and OsTRAB1. The expression of GmbZIP1 was highly induced by ABA, drought, high salt and low temperature; and GmbZIP1 was expressed in soybean roots, stems and leaves under different stress conditions. GmbZIP1 was localized inside the nuclei of transformed onion epidermal cells. Overexpression of GmbZIP1 enhanced the responses of transgenic plants to ABA and triggered stomatal closure under stresses, potentially leading to improved tolerances to several abiotic stresses such as high salt, low temperature and drought in transgenic plants. Furthermore, overexpression of GmbZIP1 affected the expression of some ABA or stress-related genes involved in regulating stomatal closure in Arabidopsis under ABA, drought and high salt stress conditions. A few AREB elements were detected in the promoter region of those ABA or stress-related genes, suggesting that GmbZIP1 regulates the ABA response or stomatal closure mediated by those downstream genes in transgenic Arabidopsis. Moreover, GmbZIP1 was used to improve the drought tolerance trait of Chinese wheat varieties BS93. Functional analysis showed that overexpression of GmbZIP1 enhanced the drought tolerance of transgenic wheat, and transcripts of GmbZIP1 were detected in transgenic wheat using RT-PCR. In addition, GmbZIP1 overexpression did not result in growth retardation in all transgenic plants, suggesting that Gmb

  7. The WRKY transcription factors in the diploid woodland strawberry Fragaria vesca: Identification and expression analysis under biotic and abiotic stresses.

    PubMed

    Wei, Wei; Hu, Yang; Han, Yong-Tao; Zhang, Kai; Zhao, Feng-Li; Feng, Jia-Yue

    2016-08-01

    WRKY proteins comprise a large family of transcription factors that play important roles in response to biotic and abiotic stresses and in plant growth and development. To date, little is known about the WRKY gene family in strawberry. In this study, we identified 62 WRKY genes (FvWRKYs) in the wild diploid woodland strawberry (Fragaria vesca, 2n = 2x = 14) accession Heilongjiang-3. According to the phylogenetic analysis and structural features, these identified strawberry FvWRKY genes were classified into three main groups. In addition, eight FvWRKY-GFP fusion proteins showed distinct subcellular localizations in Arabidopsis mesophyll protoplasts. Furthermore, we examined the expression of the 62 FvWRKY genes in 'Heilongjiang-3' under various conditions, including biotic stress (Podosphaera aphanis), abiotic stresses (drought, salt, cold, and heat), and hormone treatments (abscisic acid, ethephon, methyl jasmonate, and salicylic acid). The expression levels of 33 FvWRKY genes were upregulated, while 12 FvWRKY genes were downregulated during powdery mildew infection. FvWRKY genes responded to drought and salt treatment to a greater extent than to temperature stress. Expression profiles derived from quantitative real-time PCR suggested that 11 FvWRKY genes responded dramatically to various stimuli at the transcriptional level, indicating versatile roles in responses to biotic and abiotic stresses. Interaction networks revealed that the crucial pathways controlled by WRKY proteins may be involved in the differential response to biotic stress. Taken together, the present work may provide the basis for future studies of the genetic modification of WRKY genes for pathogen resistance and stress tolerance in strawberry. PMID:27105420

  8. Novel NAC Transcription Factor TaNAC67 Confers Enhanced Multi-Abiotic Stress Tolerances in Arabidopsis

    PubMed Central

    Mao, Xinguo; Chen, Shuangshuang; Li, Ang; Zhai, Chaochao; Jing, Ruilian

    2014-01-01

    Abiotic stresses are major environmental factors that affect agricultural productivity worldwide. NAC transcription factors play pivotal roles in abiotic stress signaling in plants. As a staple crop, wheat production is severely constrained by abiotic stresses whereas only a few NAC transcription factors have been characterized functionally. To promote the application of NAC genes in wheat improvement by biotechnology, a novel NAC gene designated TaNAC67 was characterized in common wheat. To determine its role, transgenic Arabidopsis overexpressing TaNAC67-GFP controlled by the CaMV-35S promoter was generated and subjected to various abiotic stresses for morphological and physiological assays. Gene expression showed that TaNAC67 was involved in response to drought, salt, cold and ABA treatments. Localization assays revealed that TaNAC67 localized in the nucleus. Morphological analysis indicated the transgenics had enhanced tolerances to drought, salt and freezing stresses, simultaneously supported by enhanced expression of multiple abiotic stress responsive genes and improved physiological traits, including strengthened cell membrane stability, retention of higher chlorophyll contents and Na+ efflux rates, improved photosynthetic potential, and enhanced water retention capability. Overexpression of TaNAC67 resulted in pronounced enhanced tolerances to drought, salt and freezing stresses, therefore it has potential for utilization in transgenic breeding to improve abiotic stress tolerance in crops. PMID:24427285

  9. Archaeal (Per)Chlorate Reduction at High Temperature: An Interplay of Biotic and Abiotic Reactions

    NASA Astrophysics Data System (ADS)

    Liebensteiner, Martin G.; Pinkse, Martijn W. H.; Schaap, Peter J.; Stams, Alfons J. M.; Lomans, Bart P.

    2013-04-01

    Perchlorate and chlorate anions [(per)chlorate] exist in the environment from natural and anthropogenic sources, where they can serve as electron acceptors for bacteria. We performed growth experiments combined with genomic and proteomic analyses of the hyperthermophile Archaeoglobus fulgidus that show (per)chlorate reduction also extends into the archaeal domain of life. The (per)chlorate reduction pathway in A. fulgidus relies on molybdo-enzymes that have similarity with bacterial enzymes; however, chlorite is not enzymatically split into chloride and oxygen. Evidence suggests that it is eliminated by an interplay of abiotic and biotic redox reactions involving sulfur compounds. Biological (per)chlorate reduction by ancient archaea at high temperature may have prevented accumulation of perchlorate in early terrestrial environments and consequently given rise to oxidizing conditions on Earth before the rise of oxygenic photosynthesis.

  10. Effects of biotic and abiotic factors on phenotypic partitioning of wing morphology and development in Sclerodermus pupariae (Hymenoptera: Bethylidae).

    PubMed

    Wang, Xiaoyi; Wei, Ke; Yang, Zhongqi; Jennings, David E; Duan, Jian J

    2016-01-01

    Wing phenotype polymorphism is commonly observed in insects, yet little is known about the influence of environmental cues on the development or expression of the alternative phenotypes. Here, we report how both biotic and abiotic factors affect the wing morph differentiation of a bethylid parasitoid Sclerodermus pupariae. The percentage of winged female parasitoid progeny increased exponentially with temperature between 20 °C to 30 °C. Low intensity light and short-day photoperiod conditions also significantly induced the development of winged morphs. Interestingly, wingless maternal parasitoids produced more winged progeny. Furthermore, the degree of wing dimorphism was significantly influenced by the interactions between light intensity and maternal wing morphs. The percentage of winged female progeny was not significantly influenced by foundress densities, but increased significantly with parasitoid brood sizes. However, the percentage of male progeny increased significantly with the densities of maternal parasitoids. Our findings highlight the phenotypic partitioning of wing morphology and development in the parasitoid S. pupariae under varied environmental cues, and reveal the most favourable conditions for the production of winged females in this bethylid wasp. It is thus possible to increase winged female parasitoid production for the purposes of biological control by manipulation of biotic and abiotic conditions. PMID:27194095

  11. Effects of biotic and abiotic factors on phenotypic partitioning of wing morphology and development in Sclerodermus pupariae (Hymenoptera: Bethylidae)

    PubMed Central

    Wang, Xiaoyi; Wei, Ke; Yang, Zhongqi; Jennings, David E.; Duan, Jian J.

    2016-01-01

    Wing phenotype polymorphism is commonly observed in insects, yet little is known about the influence of environmental cues on the development or expression of the alternative phenotypes. Here, we report how both biotic and abiotic factors affect the wing morph differentiation of a bethylid parasitoid Sclerodermus pupariae. The percentage of winged female parasitoid progeny increased exponentially with temperature between 20 °C to 30 °C. Low intensity light and short-day photoperiod conditions also significantly induced the development of winged morphs. Interestingly, wingless maternal parasitoids produced more winged progeny. Furthermore, the degree of wing dimorphism was significantly influenced by the interactions between light intensity and maternal wing morphs. The percentage of winged female progeny was not significantly influenced by foundress densities, but increased significantly with parasitoid brood sizes. However, the percentage of male progeny increased significantly with the densities of maternal parasitoids. Our findings highlight the phenotypic partitioning of wing morphology and development in the parasitoid S. pupariae under varied environmental cues, and reveal the most favourable conditions for the production of winged females in this bethylid wasp. It is thus possible to increase winged female parasitoid production for the purposes of biological control by manipulation of biotic and abiotic conditions. PMID:27194095

  12. Quantifying Components of Soil Respiration and Their Response to Abiotic Factors in Two Typical Subtropical Forest Stands, Southwest China

    PubMed Central

    Yu, Lei; Wang, Yujie; Wang, Yunqi; Sun, Suqi; Liu, Liziyuan

    2015-01-01

    Separating the components of soil respiration and understanding the roles of abiotic factors at a temporal scale among different forest types are critical issues in forest ecosystem carbon cycling. This study quantified the proportions of autotrophic (RA) and heterotrophic (RH) in total soil (RT) respiration using trenching and litter removal. Field studies were conducted in two typical subtropical forest stands (broadleaf and needle leaf mixed forest; bamboo forest) at Jinyun Mountain, near the Three Georges Reservoir in southwest China, during the growing season (Apr.–Sep.) from 2010 to 2012. The effects of air temperature (AT), soil temperature (ST) and soil moisture (SM) at 6cm depth, solar radiation (SR), pH on components of soil respiration were analyzed. Results show that: 1) SR, AT, and ST exhibited a similar temporal trend. The observed abiotic factors showed slight interannual variability for the two forest stands. 2) The contributions of RH and RA to RT for broadleaf and needle leaf mixed forest were 73.25% and 26.75%, respectively, while those for bamboo forest were 89.02% and 10.98%, respectively; soil respiration peaked from June to July. In both stands, CO2 released from the decomposition of soil organic matter (SOM), the strongest contributor to RT, accounted for over 63% of RH. 3) AT and ST were significantly positively correlated with RT and its components (p<0.05), and were major factors affecting soil respiration. 4) Components of soil respiration were significantly different between two forest stands (p<0.05), indicating that vegetation types played a role in soil respiration and its components. PMID:25680112

  13. Environmental Selenium Transformations: Distinguishing Abiotic and Biotic Factors Influencing Se Redox Transformations

    NASA Astrophysics Data System (ADS)

    Rosenfeld, C.; Kenyon, J.; James, B. R.; Santelli, C. M.

    2014-12-01

    Worldwide, selenium (Se) is proving to be a significant environmental concern, with many anthropogenic activities (e.g. coal mining and combustion, phosphate mining and agricultural irrigation) releasing potentially hazardous concentrations into surface and subsurface ecosystems. The US EPA is currently considering aquatic Se regulations, however no guidelines exist for excess soil Se, despite its ability to act as a persistent Se source. Various abiotic and biological processes mediate Se oxidation/reduction (redox) transformations in soils, thus influencing its solubility and bioavailability. In this research we assess (1) the ability of metal-transforming fungal species to aerobically reduce Se (Se (IV and/or VI) to Se(0)), and (2) the relative contribution of biotic and abiotic pathways for aerobic Se transformation. The primary objective of this research is to determine what abiotic and biotic factors enhance or restrict Se bioavailability. Results indicate that fungal-mediated Se reduction may be quite widespread, with at least 7 out of 10 species of known Mn(II)-oxidizing fungi isolated from metal impacted environments also identified as capable of aerobically reducing Se(IV) and/or Se(VI) to Se(0). Increasing concentrations of selenite (SeO32-; Se(IV)) and selenate (SeO42-; Se(VI)) generally reduced fungal growth rates, although selenate was more likely to inhibit fungal growth than selenite. To study oxidation, Se(0) was combined with Mn(III/IV) (hydr)oxides (henceforth referred to as Mn oxides), Se-transforming fungi (Alternaria alternata), and oxalic acid to mimic Se biogeochemistry at the plant-soil interface. Increased pH in the presence of fungi (7.2 with fungi, 6.8 without fungi after 24 days) was observed. Additionally, a slight decrease in redox potential was measured for incubations without Mn oxides (236 mV with Mn oxides, 205 mV without Mn oxides after 24 days), indicating that Mn oxides may enhance Se oxidation. Elemental Se oxidation rates to

  14. EXB1/WRKY71 transcription factor regulates both shoot branching and responses to abiotic stresses.

    PubMed

    Guo, Dongshu; Qin, Genji

    2016-03-01

    As the sessile organisms, plants evolve different strategies to survive in adverse environmental conditions. The elaborate regulation of shoot branching is an important strategy for plant morphological adaptation to various environments, while the regulation of reactive oxygen species (ROS), salicylic acid (SA) and jasmonic acid (JA) is pivotal for plant responses to biotic and abiotic stresses. Recently, we have demonstrated that Arabidopsis EXB1, a WRKY transcription factor, is a positive regulator of shoot branching as a cover story in Plant Cell. Here we show that WRKY23, an EXB1 close member, has a redundant role in control of shoot branching. We further show that EXB1 is induced by H2O2, ABA or mannitol treatments, suggesting that EXB1 may also play roles in plant responses to abiotic stresses. RNA-sequencing (RNA-seq) analysis using 4EnhpEXB1-EXB1GR inducible line indicates that the genes involved in oxidative stress, oxidation reduction, SA or JA signaling pathway are regulated by EXB1 induction in a short time. We suggest that EXB1/WRKY71 transcription factor may play pivotal roles in plant adaptation to environments by both morphological and physiological ways. PMID:26914912

  15. Abiotic Formation of Valine Peptides Under Conditions of High Temperature and High Pressure

    NASA Astrophysics Data System (ADS)

    Furukawa, Yoshihiro; Otake, Tsubasa; Ishiguro, Takato; Nakazawa, Hiromoto; Kakegawa, Takeshi

    2012-12-01

    We investigated the oligomerization of solid valine and the stabilities of valine and valine peptides under conditions of high temperature (150-200 °C) and high pressure (50-150 MPa). Experiments were performed under non-aqueous condition in order to promote dehydration reaction. After prolonged exposure of monomeric valine to elevated temperatures and pressures, the products were analyzed by liquid chromatography mass spectrometry comparing their retention times and masses. We identified linear peptides that ranged in size from dimer to hexamer, as well as a cyclic dimer. Previous studies that attempted abiotic oligomerization of valine in the absence of a catalyst have never reported valine peptides larger than a dimer. Increased reaction temperature increased the dissociative decomposition of valine and valine peptides to products such as glycine, β-alanine, ammonia, and amines by processes such as deamination, decarboxylation, and cracking. The amount of residual valine and peptide yields was greater at higher pressures at a given temperature, pressure, and reaction time. This suggests that dissociative decomposition of valine and valine peptides is reduced by pressure. Our findings are relevant to the investigation of diagenetic processes in prebiotic marine sediments where similar pressures occur under water-poor conditions. These findings also suggest that amino acids, such as valine, could have been polymerized to peptides in deep prebiotic marine sediments within a few hundred million years.

  16. Diverse expression pattern of wheat transcription factors against abiotic stresses in wheat species.

    PubMed

    Baloglu, Mehmet Cengiz; Inal, Behcet; Kavas, Musa; Unver, Turgay

    2014-10-15

    Abiotic stress including drought and salinity affects quality and yield of wheat varieties used for the production of both bread and pasta flour. bZIP, MBF1, WRKY, MYB and NAC transcription factor (TF) genes are the largest transcriptional regulators which are involved in growth, development, physiological processes, and biotic/abiotic stress responses in plants. Identification of expression profiling of these TFs plays a crucial role to understand the response of different wheat species against severe environmental changes. In the current study, expression analysis of TaWLIP19 (wheat version of bZIP), TaMBF1, TaWRKY10, TaMYB33 and TaNAC69 genes was examined under drought and salinity stress conditions in Triticum aestivum cv. (Yuregir-89), Triticum turgidum cv. (Kiziltan-91), and Triticum monococcum (Siyez). After drought stress application, all five selected genes in Kiziltan-91 were induced. However, TaMBF1 and TaWLIP19 were the only downregulated genes in Yuregir-89 and Siyez, respectively. Except TaMYB33 in Siyez, expression level of the remaining genes increased under salt stress condition in all Triticum species. For determination of drought response to selected TF members, publicly available RNA-seq data were also analyzed in this study. TaMBF1, TaWLIP19 and TaNAC69 transcripts were detected through in silico analysis. This comprehensive gene expression analysis provides valuable information for understanding the roles of these TFs under abiotic stresses in modern wheat cultivars and ancient einkorn wheat. In addition, selected TFs might be used for determination of drought or salinity-tolerant and susceptible cultivars for molecular breeding studies. PMID:25130909

  17. The Miscanthus NAC transcription factor MlNAC9 enhances abiotic stress tolerance in transgenic Arabidopsis.

    PubMed

    Zhao, Xun; Yang, Xuanwen; Pei, Shengqiang; He, Guo; Wang, Xiaoyu; Tang, Qi; Jia, Chunlin; Lu, Ying; Hu, Ruibo; Zhou, Gongke

    2016-07-15

    NAC (NAM, ATAF1/2, and CUC2) transcription factors are known to play important roles in responses to abiotic stresses in plants. Currently, little information regarding the functional roles of NAC genes in stress tolerance is available in Miscanthus lutarioriparius, a promising bioenergy plant for cellulosic ethanol production. In this study, we carried out the functional characterization of MlNAC9 in abiotic stresses. MlNAC9 was shown to act as a nuclear localized transcription activator with the activation domain in its C-terminus. The overexpression of MlNAC9 in Arabidopsis conferred hypersensitivity to abscisic acid (ABA) at seed germination and root elongation stages. In addition, the overexpression of MlNAC9 led to increased seed germination rate and root growth under salt (NaCl) treatment. Meanwhile, the transgenic Arabidopsis overexpressing MlNAC9 showed enhanced tolerance to drought and cold stresses. The expression of stress-responsive marker genes was significantly increased in MlNAC9 overexpression lines compared to that of WT under ABA, drought, salt, and cold stresses. Correspondingly, the activities of antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were significantly increased and the malondialdehyde (MDA) content was lower accumulated in MlNAC9 overexpression lines under drought and salt treatments. These results indicated that the overexpression of MlNAC9 improved the tolerance to abiotic stresses via an ABA-dependent pathway, and the enhanced tolerance of transgenic plants was mainly attributed to the increased expression of stress-responsive genes and the enhanced scavenging capability of reactive oxygen species (ROS). PMID:27085481

  18. Influence of biotic and abiotic factors on the allelopathic activity of the cyanobacterium Cylindrospermopsis raciborskii strain LEGE 99043.

    PubMed

    Antunes, Jorge T; Leão, Pedro N; Vasconcelos, Vítor M

    2012-10-01

    Allelopathy is considered to be one of the factors underlying the global expansion of the toxic cyanobacterium Cylindrospermopsis raciborskii. Although the production and release of allelopathic compounds by cyanobacteria is acknowledged to be influenced by environmental parameters, the response of C. raciborskii remains generally unrecognized. Here, the growth and allelopathic potential of C. raciborskii strain LEGE 99043 towards the ubiquitous microalga Ankistrodesmus falcatus were analyzed under different biotic and abiotic conditions. Filtrates from C. raciborskii cultures growing at different cell densities displayed broad inhibitory activity. Moreover, higher temperature, higher light intensity as well phosphate limitation further enhanced this activity. The distinct and comprehensive patterns of inhibition verified during the growth phase, and under the tested parameters, suggest the action of several, still unidentified allelopathic compounds. It is expectable that the observed increase in allelopathic activity can result in distinct ecological advantages to C. raciborskii. PMID:22562107

  19. Reduced tolerance to abiotic stress in transgenic Arabidopsis overexpressing a Capsicum annuum multiprotein bridging factor 1

    PubMed Central

    2014-01-01

    Background The pepper fruit is the second most consumed vegetable worldwide. However, low temperature affects the vegetative development and reproduction of the pepper, resulting in economic losses. To identify cold-related genes regulated by abscisic acid (ABA) in pepper seedlings, cDNA representational difference analysis was previously performed using a suppression subtractive hybridization method. One of the genes cloned from the subtraction was homologous to Solanum tuberosum MBF1 (StMBF1) encoding the coactivator multiprotein bridging factor 1. Here, we have characterized this StMBF1 homolog (named CaMBF1) from Capsicum annuum and investigated its role in abiotic stress tolerance. Results Tissue expression profile analysis using quantitative RT-PCR showed that CaMBF1 was expressed in all tested tissues, and high-level expression was detected in the flowers and seeds. The expression of CaMBF1 in pepper seedlings was dramatically suppressed by exogenously supplied salicylic acid, high salt, osmotic and heavy metal stresses. Constitutive overexpression of CaMBF1 in Arabidopsis aggravated the visible symptoms of leaf damage and the electrolyte leakage of cell damage caused by cold stress in seedlings. Furthermore, the expression of RD29A, ERD15, KIN1, and RD22 in the transgenic plants was lower than that in the wild-type plants. On the other hand, seed germination, cotyledon greening and lateral root formation were more severely influenced by salt stress in transgenic lines compared with wild-type plants, indicating that CaMBF1-overexpressing Arabidopsis plants were hypersensitive to salt stress. Conclusions Overexpression of CaMBF1 in Arabidopsis displayed reduced tolerance to cold and high salt stress during seed germination and post-germination stages. CaMBF1 transgenic Arabidopsis may reduce stress tolerance by downregulating stress-responsive genes to aggravate the leaf damage caused by cold stress. CaMBF1 may be useful for genetic engineering of novel

  20. Geographic variation of floral traits in Nicotiana glauca : Relationships with biotic and abiotic factors

    NASA Astrophysics Data System (ADS)

    Nattero, Julieta; Sérsic, Alicia N.; Cocucci, Andrea A.

    2011-09-01

    Geographic pattern of phenotypic variation can appear in a clinal or a mosaic fashion and can evidence adaptive or non-adaptive variation. To shed light on the mechanisms underlying this variation, we studied the relationships between geographic variation of floral traits and both biotic and abiotic factors of the hummingbird-pollinated plant, Nicotiana glauca, across its natural range. We obtained floral measures of 38 populations from an area about 1600 km long and 1050 km wide and an altitude range from 7 to over 3400 m. We used a MANOVA to detect between-population differentiations in flower traits and a DFA to determine the traits that best discriminate between populations. To test for associations between floral traits and climatic variables we used correlation analysis. We explored any possible distance-based pattern of variation (either geographic or altitudinal) in floral traits or bill length of pollinators using Mantel tests. Finally, we used a multiple regression to analyze simultaneously the effects and relative importance of abiotic predictor variables and bill length on corolla length. We found a high variation in flower traits among populations. Morphometric traits were the ones that best discriminated across populations. There was a clinal pattern of floral phenotypic variation explained by climatic factors. Differences in floral phenotypic distances were structured by altitudinal distances but not by geographic distances. Bill length of the hummingbird pollinators was structured both by altitudinal and geographic distances. Differences in bill length of hummingbird pollinators explained differences in corolla length across populations. Our findings support the assumption of flower evolution at a broad geographic scale. Floral traits seem to be structured not only by altitude but also by climatic factors.

  1. Biotic and abiotic bisphenol-A removal from wastewater by activated sludge: effects of temperature, biomass, and bisphenol-A concentrations.

    PubMed

    Keskinkan, Olcayto; Balci, Behzat

    2016-01-01

    In this study, bisphenol-A (BPA) removal from synthetic wastewaters using a laboratory-scale activated sludge system was achieved. Activated (biotic) sludge was used for BPA elimination, whereas inactivated (abiotic) sludge was used during the adsorption study. In each step, six different BPA concentrations (5, 10, 20, 30, 40, and 50 mg L(-1)) were tested, and temperatures were set to 10, 20, and 30 °C in the shakers. Four different activated sludge concentrations (1,000, 2,000, 3,000, and 4,000 mg TSS L(-1)) were applied in the biotic study, and only 2,000 mg TSS L(-1) was used in the abiotic study. After settlement of the sludge in the shakers, supernatants and control groups were filtered and analyzed for BPA using high performance liquid chromatography. In the biotic study, BPA and chemical oxygen demand (COD) concentrations were reduced at 100% and 99% levels, respectively. However, the BPA concentrations during the abiotic study changed slightly at varying temperatures, whereas there was no change of BPA concentration observed in the control groups. Results indicate that the main factor of BPA removal in an activated sludge system is biological. Kinetic studies were also conducted. BPA removal was best fit to zero- and first-order reaction kinetics, and the reaction rate constants are provided in this paper. PMID:26819387

  2. Novel DREB A-5 subgroup transcription factors from desert moss (Syntrichia caninervis) confers multiple abiotic stress tolerance to yeast.

    PubMed

    Li, Haiyan; Zhang, Daoyuan; Li, Xiaoshuang; Guan, Kaiyun; Yang, Honglan

    2016-05-01

    Syntrichia caninervis Mitt. is a typical desiccation tolerant moss from a temperate desert which has been a good resource for stress tolerant gene isolation. Dehydration responsive element binding proteins (DREBs) was proven to play an important role in responding to abiotic stress, which has been identified in many plants, and were rarely reported in moss. In this study, we cloned ten DREB genes from S. caninervis, and investigated their abiotic stress response and stress tolerance. The results showed that ten ScDREB proteins belonged to the A-5 sub-group of the DREB sub-family. Six genes, ScDREB1, ScDREB2, ScDREB4, ScDREB6, ScDREB7, and ScDREB8 were involved in the ABA-dependent signal pathway and the desiccation, salt, and cold stress response. ScDREB3 also responded to desiccation, salt, and cold stresses, but was insensitive to ABA treatment. Another gene, ScDREB5, was involved in an ABA-independent cold stress-responsive signal pathway. Two genes, ScDREB9 and ScDREB10, responded slightly or had no response to neither stress factor or ABA treatment. We transformed four typical genes into yeast cells and the stress tolerance ability of transgenic yeast was evaluated. The results showed that ScDREB3 and ScDREB5 enhanced the yeast's cold and salt tolerance. ScDREB8 and ScDREB10 conferred the osmotic, salt, cold, and high temperature stresses tolerance, especially for osmotic and salt stresses. Our results indicated that A-5 sub-group DREB genes in S. caninervis played important roles in abiotic stresses response and enhanced stress tolerance to transgenic yeast. To our knowledge, this is the first report on DREB genes characterization from desiccation tolerant moss, and this study will not only provide insight into the molecular mechanisms of S. caninervis adaptation to environmental stresses, but also provides valuable gene candidates for plant molecular breeding. PMID:27016184

  3. The wheat transcription factor, TabHLH39, improves tolerance to multiple abiotic stressors in transgenic plants.

    PubMed

    Zhai, Yiqian; Zhang, Lichao; Xia, Chuan; Fu, Silu; Zhao, Guangyao; Jia, Jizeng; Kong, Xiuying

    2016-05-13

    Although bHLH transcription factors play important roles regulating plant development and abiotic stress response and tolerance, few functional studies have been performed in wheat. In this study, we isolated and characterized a bHLH gene, TabHLH39, from wheat. The TabHLH39 gene is located on wheat chromosome 5DL, and the protein localized to the nucleus and activated transcription. TabHLH39 showed variable expression in roots, stems, leaves, glumes, pistils and stamens and was induced by polyethylene glycol, salt and cold treatments. Further analysis revealed that TabHLH39 overexpression in Arabidopsis significantly enhanced tolerance to drought, salt and freezing stress during the seedling stage, which was also demonstrated by enhanced abiotic stress-response gene expression and changes to several physiological indices. Therefore, TabHLH39 has potential in transgenic breeding applications to improve abiotic stress tolerance in crops. PMID:27091431

  4. Inter-annual variability of carbon fluxes in temperate forest ecosystems: effects of biotic and abiotic factors

    NASA Astrophysics Data System (ADS)

    Chen, M.; Keenan, T. F.; Hufkens, K.; Munger, J. W.; Bohrer, G.; Brzostek, E. R.; Richardson, A. D.

    2014-12-01

    Carbon dynamics in terrestrial ecosystems are influenced by both abiotic and biotic factors. Abiotic factors, such as variation in meteorological conditions, directly drive biophysical and biogeochemical processes; biotic factors, referring to the inherent properties of the ecosystem components, reflect the internal regulating effects including temporal dynamics and memory. The magnitude of the effect of abiotic and biotic factors on forest ecosystem carbon exchange has been suggested to vary at different time scales. In this study, we design and conduct a model-data fusion experiment to investigate the role and relative importance of the biotic and abiotic factors for inter-annual variability of the net ecosystem CO2 exchange (NEE) of temperate deciduous forest ecosystems in the Northeastern US. A process-based model (FöBAAR) is parameterized at four eddy-covariance sites using all available flux and biometric measurements. We conducted a "transplant" modeling experiment, that is, cross- site and parameter simulations with different combinations of site meteorology and parameters. Using wavelet analysis and variance partitioning techniques, analysis of model predictions identifies both spatial variant and spatially invariant parameters. Variability of NEE was primarily modulated by gross primary productivity (GPP), with relative contributions varying from hourly to yearly time scales. The inter-annual variability of GPP and NEE is more regulated by meteorological forcing, but spatial variability in certain model parameters (biotic response) has more substantial effects on the inter-annual variability of ecosystem respiration (Reco) through the effects on carbon pools. Both the biotic and abiotic factors play significant roles in modulating the spatial and temporal variability in terrestrial carbon cycling in the region. Together, our study quantifies the relative importance of both, and calls for better understanding of them to better predict regional CO2

  5. Influence of abiotic factors on cathemeral activity: the case of Eulemur fulvus collaris in the littoral forest of Madagascar.

    PubMed

    Donati, Giuseppe; Borgognini-Tarli, Silvana M

    2006-01-01

    The role environmental factors play in influencing circadian rhythms in natural habitats is still poorly described in primates, especially for those taxa with an activity cycle extended over the 24-hour cycle. In this paper, we elucidate the importance of abiotic factors in entraining the activity of cathemeral primates, focussing on results from a long-term study of Eulemur fulvus collaris (collared brown lemur) in south-eastern Malagasy littoral forest. Two groups of lemurs were followed for 60 whole-day and 59 whole-night observation periods over 14 months. Diurnal and nocturnal observations were equally distributed among moon phases and seasons. Temperature and humidity were recorded hourly by automatic data loggers. The littoral forest has a climatic environment where rainfall and humidity are uncorrelated with temperature and photoperiod. Diurnal and nocturnal activity varied seasonally, with the former increasing significantly with extended day length and the latter increasing significantly with shortened day length. Dusk seemed to act as a primary zeitgeber for these lemurs, coordinating the onset of evening activity throughout the entire year. Lunar phase and the nocturnal luminosity index correlated positively with the duration of nocturnal activity and negatively with the length of diurnal activity. Temperature was positively associated with diurnal activity but did not seem to influence lemur rhythms at night. Finally, lemur nocturnal activity significantly decreased when levels of humidity and rainfall were high. Cathemeral biorhythm is triggered by zeitgebers and influenced by masking factors. The activity of collared brown lemurs appears to be seasonally influenced by photoperiod and directly modulated by nocturnal ambient luminosity. These results are discussed by comparing data from other cathemeral species living in various climatic situations. PMID:16415580

  6. Abiotic and biotic factors that influence the bioavailability of gold nanoparticles to aquatic macrophytes.

    PubMed

    Glenn, J Brad; Klaine, Stephen J

    2013-09-17

    This research identified and characterized factors that influenced nanomaterial bioavailability to three aquatic plants: Azolla caroliniana Willd, Egeria densa Planch., and Myriophyllum simulans Orch. Plants were exposed to 4-, 18-, and 30-nm gold nanoparticles. Uptake was influenced by nanoparticle size, the presence of roots on the plant, and dissolved organic carbon in the media. Statistical analysis of the data also revealed that particle uptake was influenced by a 4-way (plant species, plant roots, particle size, and dissolved organic carbon) interaction suggesting nanoparticle bioavailability was a complex result of multiple parameters. Size and species dependent absorption was observed that was dependent on the presence of roots and nanoparticle size. The presence of dissolved organic carbon was found to associate with 4- and 18-nm gold nanoparticles in suspension and form a nanoparticle/organic matter complex that resulted in (1) minimized particle aggregation and (2) a decrease of nanoparticle absorption by the aquatic plants. The same effect was not observed with the 30-nm nanoparticle treatment. These results indicate that multiple factors, both biotic and abiotic, must be taken into account when predicting bioavailability of nanomaterials to aquatic plants. PMID:23947987

  7. Abiotic factors influencing the spatial and temporal variability of juvenile fish in Pamlico Sound, North Carolina

    SciTech Connect

    Pietrafesa, L.J.; Janowitz, G.S.; Miller, J.M.; Noble, E.B.; Ross, S.W.; Epperly, S.P.

    1985-07-01

    A 3-D, time dependent model of the circulation in Pamlico Sound, NC, is used to relate the direction and magnitude of winds to the number of juvenile fish sampled at specified estuarine nursery locations. NC marine sport fishes are known to be spawned in NC continental waters, and then make transit to an through barrier island inlets, into Pamlico Sound. The juveniles then move 40-70 kilometers across the Sound to the nurseries. It is hypothesized that wind driven, pressure gradient induced and topographically steered currents, all abiotic factors, provide the transport mechanisms, during the recruitment period February-April, necessary for the transect. Moreover, the inherent variability in the atmospherically derived physical factors and the influence of topographic irregularities such as a large shoal which laterally bisects the Sound and bifurcates the bottom currents are seen as sources of the temporal and spatial variation observed in the distribution of juvenile fish, while the influence of biological processes is viewed as providing fine-tuned structuring.

  8. Effects of biotic and abiotic factors on the distribution of trout and salmon along a longitudinal stream gradient

    USGS Publications Warehouse

    De La, Hoz, Franco, E. A.; Budy, P.

    2005-01-01

    We examined the influence of biotic and abiotic factors on the distribution, abundance, and condition of salmonid fishes along a stream gradient. We observed a longitudinal change in fish distribution with native cutthroat trout, Oncorhynchus clarki utah, and introduced brown trout, Salmo trutta, demonstrating a distinct pattern of allopatry. Cutthroat trout dominated high elevation reaches, while reaches at lower elevations were dominated by brown trout. A transition zone between these populations was associated with lower total trout abundance, consistent changes in temperature and discharge, and differences in dietary preference. Variation in cutthroat trout abundance was best explained by a model including the abundance of brown trout and diel temperature, whereas variation in brown trout abundance was best explained by a model including the abundance of cutthroat trout and discharge. These results suggest the potential for condition-mediated competition between the two species. The results from our study can aid biologists in prioritizing conservation activities and in developing robust management strategies for cutthroat trout. ?? Springer 2005.

  9. [Biotic and abiotic factors that affect the quality of Schinopsis balansae Engl. and Aspidosperma quebracho-blanco Schltdl. seeds].

    PubMed

    Alzugaray, Claudia; Carnevale, Nélida J; Salinas, Adriana R; Pioli, Rosanna

    2007-06-01

    Aspidosperma quebracho-blanco (white quebracho) and Schinopsis balansae (red quebracho) are distinctive trees of the South American Park in Argentina. Quebrachos are found in forests that have been exploited very intensively. The object of this work was the identification of biotic and abiotic factors specially fungal pathogen that affect the quality of both species and its relation with germination. Seeds where evaluated through germination test and the percentage of the incidence of fungal agents in two different years of harvest was determined. In S. balansae the germination rate was 77% and of 27% in 2000 and 2001 harvests, respectively. Associations fungi-germination were found in 2001 for Alternaria spp., Curvularia spp., and Fusarium spp., showing an coefficient of correlation = -0.84; -0.85 and -0.73 (p < 0.00004), respectively. A high percentage of vane seeds (55%) was also found in 2001 harvest, due to adverse environmental factors, specifically higher precipitations during flowering. In A. quebracho-blanco seeds, the germination rate was 50% and 90% in 2000 and 2003 respectively, with a 42% of immature seeds in 2000 harvest that was associated to high precipitations and high temperatures during flowering and ripping of fruits. The incidence of pathogens was low and did not have association to germination. PMID:17604434

  10. Mycobacterium ulcerans dynamics in aquatic ecosystems are driven by a complex interplay of abiotic and biotic factors

    PubMed Central

    Garchitorena, Andrés; Guégan, Jean-François; Léger, Lucas; Eyangoh, Sara; Marsollier, Laurent; Roche, Benjamin

    2015-01-01

    Host–parasite interactions are often embedded within complex host communities and can be influenced by a variety of environmental factors, such as seasonal variations in climate or abiotic conditions in water and soil, which confounds our understanding of the main drivers of many multi-host pathogens. Here, we take advantage of a combination of large environmental data sets on Mycobacterium ulcerans (MU), an environmentally persistent microorganism associated to freshwater ecosystems and present in a large variety of aquatic hosts, to characterize abiotic and biotic factors driving the dynamics of this pathogen in two regions of Cameroon. We find that MU dynamics are largely driven by seasonal climatic factors and certain physico-chemical conditions in stagnant and slow-flowing ecosystems, with an important role of pH as limiting factor. Furthermore, water conditions can modify the effect of abundance and diversity of aquatic organisms on MU dynamics, which suggests a different contribution of two MU transmission routes for aquatic hosts (trophic vs environmental transmission) depending on local abiotic factors. DOI: http://dx.doi.org/10.7554/eLife.07616.001 PMID:26216042

  11. Combined effects of Corexit EC 9500A with secondary abiotic and biotic factors in the rotifer Brachionus plicatilis.

    PubMed

    Williams, Michael B; Powell, Mickie L; Watts, Stephen A

    2016-10-01

    We examined lethality and behavioral effects of Corexit EC 9500A (C-9500A) exposure on the model marine zooplankton Brachionus plicatilis singularly and in combination with abiotic and biotic factors. C-9500A exposure at standard husbandry conditions (17.5ppt, 24°C, 200 rotifer*mL(-1) density) identified the 24h median lethal concentration, by Probit analysis, to be 107ppm for cultured B. plicatilis. Rotifers surviving exposure to higher concentrations (100 and 150ppm) exhibited a decreased swimming velocity and a reduced net to gross movement ratio. Significant interaction between C-9500A exposure and temperature or salinity was observed. Upper thermal range was reduced and maximal salinity stress was seen as ca. 25ppt. Increased or decreased nutritional availability over the exposure period did not significantly alter mortality of B. plicatilis populations at the concentrations tested. Results from this study may be useful for predicting possible outcomes on marine zooplankton following dispersant application under diverse natural conditions. PMID:27327395

  12. Genomic identification of group A bZIP transcription factors and their responses to abiotic stress in carrot.

    PubMed

    Que, F; Wang, G L; Huang, Y; Xu, Z S; Wang, F; Xiong, A S

    2015-01-01

    The basic-region/leucine-zipper (bZIP) family is one of the major transcription factor (TF) families associated with responses to abiotic stresses. Many members of group A in this family have been extensively examined and are reported to perform significant functions in ABA signaling as well as in responses to abiotic stresses. In this study, 10 bZIP factors in carrot were classified into group A based on their DNA-binding domains. The cis-acting regulatory elements and folding states of these 10 factors were analyzed. Evolutionary analysis of the group A members suggested their importance during the course of evolution in plants. In addition, cis-acting elements and the folding state of proteins were important for DNA binding and could affect gene expression. Quantitative RT-PCR was conducted to investigate the stress response of 10 genes encoding the group A factors. Six genes showed responses to abiotic stresses, while four genes showed other special phenomenon. The current analysis on group A bZIP family TFs in carrot is the first to investigate the TFs of Apiaceae via genome analysis. These results provide new information for future studies on carrot. PMID:26535641

  13. Coupling effects of abiotic and biotic factors on molecular composition of dissolved organic matter in a freshwater wetland.

    PubMed

    He, Wei; Choi, Ilhwan; Lee, Jung-Joon; Hur, Jin

    2016-02-15

    In this study, temporal and spatial variations in five defined molecular size fractions of dissolved organic matter (DOM) were examined for a well preserved wetland (Upo Wetland) and its surrounding areas, and the influencing factors were explored with many biotic and abioic parameters. For each DOM sample, the five size fractions were determined by size-exclusion chromatography coupled with organic carbon detector (SEC-OCD). For 2-year long monthly monitoring, bio-polymers (BP), humic substances (HS), building blocks (BB), low molecular-weight (LMW) neutrals, and LMW acids displayed the median values of 264, 1884, 1070, 1090, and 11 μg-CL(-1), respectively, accounting for 6.2%, 41.7%, 24.5%, 26.4%, and 0.4% of dissolved organic carbon (DOC). The dominant presence of HS indicated that terrestrial input played important roles in DOM composition of the freshwater ecosystem, which contrasted with coastal wetlands in other reports. Both seasonal and periodic patterns in the variations were found only for HS and BB among the size fractions. It was also notable that the sources of HS were seasonally shifted from aquagenic origin in winter to pedogenic origin in summer. The correlations among the size fractions revealed that BB and LMW neutrals might be degradation products from HS and humic-like substances (HS+BB), respectively, while LMW acids, from LMW neutrals. Principle component analysis revealed that the humic-like substances and the aromaticity of DOM were associated with temperature, chlorophyll a, phosphorous, and rainfall, whereas the other fractions and the molecular weight of HS were primarily affected by solar irradiation. Significant correlations between DOM composition and some biotic factors further suggested that DOM may even affect the biological communities, which provides an insight into the potential coupling effects of biotic and abiotic factors on DOM molecular composition in freshwater wetlands. PMID:26674681

  14. Carbon Isotopes of Alkanes in Hydrothermal Abiotic Organic Synthesis Processes at High Temperatures and Pressures: An Experimental Study

    NASA Technical Reports Server (NTRS)

    Fu, Qi; Socki, Richard A.; Niles, Paul B.

    2010-01-01

    Observation of methane in the Martian atmosphere has been reported by different detection techniques [1-4]. With more evidence showing extensive water-rock interaction in Martian history [5-7], abiotic formation by Fischer-Tropsch Type (FTT) synthesis during serpentization reactions may be one possible process responsible for methane generation on Mars [8, 9]. While the experimental studies performed to date leave little doubt that chemical reactions exist for the abiotic synthesis of organic compounds by mineral surface-catalyzed reactions [10-12], little is known about the reaction pathways by which CO2 and/or CO are reduced under hydrothermal conditions. Carbon and hydrogen isotope measurements of alkanes have been used as an effective tool to constrain the origin and reaction pathways of hydrocarbon formation. Alkanes generated by thermal breakdown of high molecular weight organic compounds have carbon and hydrogen isotopic signatures completely distinct from those formed abiotically [13-15]. Recent experimental studies, however, showed that different abiogenic hydrocarbon formation processes (e.g., polymerization vs. depolymerization) may have different carbon and hydrogen isotopic patterns [16]. Results from previous experiments studying decomposition of higher molecular weight organic compounds (lignite) also suggested that pressure could be a crucial factor affecting fractionation of carbon isotopes [17]. Under high pressure conditions, no experimental data are available describing fractionation of carbon isotope during mineral catalyzed FTT synthesis. Thus, hydrothermal experiments present an excellent opportunity to provide the requisite carbon isotope data. Such data can also be used to identify reaction pathways of abiotic organic synthesis under experimental conditions.

  15. Developing standards for environmental toxicants: the need to consider abiotic environmental factors and microbe-mediated ecologic processes.

    PubMed Central

    Babich, H; Stotzky, G

    1983-01-01

    This article suggests and discusses two novel aspects for the formulation of standards for environmental toxicants. First, uniform national standards for each pollutant will be underprotective for some ecosystems and overprotective for others, inasmuch as the toxicity of a pollutant to the indigenous biota is dependent on the physicochemical properties of the recipient environment. As the number of chemicals that need regulation is immense and as microbes appear to respond similarly to pollutant-abiotic factor interactions as do plants and animals, it is suggested that microbial assays be used initially to identify those abiotic factors that most influence the toxicity of specific pollutants. Thereafter, additional studies using plants and animals can focus on these pollutant-abiotic factor interactions, and more meaningful standards can then be formulated more rapidly and inexpensively. Second, it is suggested that the response to pollutants of microbe-mediated ecologic processes be used to quantitate the sensitivity of different ecosystems to various toxicants. Such a quantification, expressed in terms of an "ecological dose 50%" (EcD50), could be easily incorporated into the methodologies currently used to set water quality criteria and would also be applicable to setting criteria for terrestrial ecosystems. PMID:6339225

  16. Effect of abiotic factors on the mercury reduction process by humic acids in aqueous systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mercury (Hg) in the environment can have serious toxic effects on a variety of living organisms, and is a pollutant of concern worldwide. The reduction of mercury from the toxic Hg2+ form to Hg0 is especially important. One pathway for this reduction to occur is through an abiotic process with humic...

  17. TaNAC2, a NAC-type wheat transcription factor conferring enhanced multiple abiotic stress tolerances in Arabidopsis

    PubMed Central

    Mao, Xinguo; Zhang, Hongying; Qian, Xueya; Li, Ang; Zhao, Guangyao; Jing, Ruilian

    2012-01-01

    Environmental stresses such as drought, salinity, and cold are major factors that significantly limit agricultural productivity. NAC transcription factors play essential roles in response to various abiotic stresses. However, the paucity of wheat NAC members functionally characterized to date does not match the importance of this plant as a world staple crop. Here, the function of TaNAC2 was characterized in Arabidopsis thaliana. A fragment of TaNAC2 was obtained from suppression subtractive cDNA libraries of wheat treated with polyethylene glycol, and its full-length cDNA was obtained by searching a full-length wheat cDNA library. Gene expression profiles indicated that TaNAC2 was involved in response to drought, salt, cold, and abscisic acid treatment. To test its function, transgenic Arabidopsis lines overexpressing TaNAC2–GFP controlled by the cauliflower mosaic virus 35S promoter were generated. Overexpression of TaNAC2 resulted in enhanced tolerances to drought, salt, and freezing stresses in Arabidopsis, which were simultaneously demonstrated by enhanced expression of abiotic stress-response genes and several physiological indices. Therefore, TaNAC2 has potential for utilization in transgenic breeding to improve abiotic stress tolerances in crops. PMID:22330896

  18. The Potential for Low-Temperature Abiotic Hydrogen Generation and a Hydrogen-Driven Deep Biosphere

    PubMed Central

    Huang, Shanshan; Thorseth, Ingunn H.

    2011-01-01

    Abstract The release and oxidation of ferrous iron during aqueous alteration of the mineral olivine is known to reduce aqueous solutions to such extent that molecular hydrogen, H2, forms. H2 is an efficient energy carrier and is considered basal to the deep subsurface biosphere. Knowledge of the potential for H2 generation is therefore vital to understanding the deep biosphere on Earth and on extraterrestrial bodies. Here, we provide a review of factors that may reduce the potential for H2 generation with a focus on systems in the core temperature region for thermophilic to hyperthermophilic microbial life. We show that aqueous sulfate may inhibit the formation of H2, whereas redox-sensitive compounds of carbon and nitrogen are unlikely to have significant effect at low temperatures. In addition, we suggest that the rate of H2 generation is proportional to the dissolution rate of olivine and, hence, limited by factors such as reactive surface areas and the access of water to fresh surfaces. We furthermore suggest that the availability of water and pore/fracture space are the most important factors that limit the generation of H2. Our study implies that, because of large heat flows, abundant olivine-bearing rocks, large thermodynamic gradients, and reduced atmospheres, young Earth and Mars probably offered abundant systems where microbial life could possibly have emerged. Key Words: Serpentinization—Olivine—Hydrogen—Deep biosphere—Water—Mars. Astrobiology 11, 711–724. PMID:21923409

  19. Recovery of white sturgeon populations through natural production: Understanding the influence of abiotic and biotic factors on spawning and subsequent recruitment

    USGS Publications Warehouse

    Parsley, M.J.; Anders, P.J.; Miller, A.I.; Beckman, L.G.; McCabe, G.T., Jr.

    2002-01-01

    Recovery or maintenance of sturgeon populations through natural production in perturbed rivers requires adequate knowledge of the abiotic and biotic factors that influence spawning and cause mortality of embryonic, larval, and juvenile life stages. Although it is known that year-class strength of white sturgeon Acipenser transmontanus is determined within 2-3 months after spawning, little is known about specific causes of mortality to early life stages during this period. Initial spawning success is critical in the development of a strong year-class, and maximized recruitment may be dependent upon water temperature and the availability of optimal in-river habitat. Analyses have shown that increased river discharge combined with suitable water temperatures during spawning, egg incubation, yolk sac larvae dispersal, and first exogenous feeding result in greater recruitment. However, little is known about the importance of other variables, such as food availability or losses due to predation that influence year-class strength. ?? 2002 by the American Fisheries Society.

  20. [Variation characteristic in soil respiration of apple orchard and its biotic and abiotic influencing factors].

    PubMed

    Wang, Rui; Guo, Sheng-Li; Liu, Qing-Fang; Zhang, Yan-Jun; Jiang, Ji-Shao; Guo, Hui-Min; Li, Ru-Jian

    2014-05-01

    To evaluate the orchard variability of soil respiration and the response of soil respiration to its influencing factors is helpful for a deep understanding about the effects of converting cropland to apple orchard. A field experiment was conducted in the Changwu State Key Agro-Ecological Station. Soil respiration, soil temperature, soil moisture and roots biomasses were periodically measured in a mature apple orchard during 2011 and 2012. Soil respiration decreased as the distance from the trunk increased. The cumulative soil respiration in the 0.5 m-distance from the trunk was 20% and 31% higher than that in the 2 m-distance from the trunk, respectively in 2011 and 2012. The temperature sensitivity of soil respiration (Q10) was relatively lower in the 2 m-distance than that in the 0. 5 m-distance in both years. Soil temperature and soil moisture were slightly higher in the 2 m-distance, but there was no significant difference between the 2 m-distance and the 0. 5 m-distance. Soil respiration and soil temperature showed a significant exponential relationship, but there was no positive correlation between soil moisture and soil respiration. Soil temperature changes can explain seasonal variation of soil respiration well, but it could not explain its spatial variability. Root density was an important factor for the spatial variability of soil respiration and Q15. Variation of soil respiration coefficient was 23% -31%. Therefore, the distance from the trunk should be considered when estimating orchards soil respiration. PMID:25055686

  1. Abiotic stress of ambient cold temperature regulates the host receptivity to pathogens by cell surfaced sialic acids.

    PubMed

    Moon, Seong-Cheol; Joo, Su-Yeon; Chung, Tae-Wook; Choi, Hee-Jung; Park, Mi-Ju; Choi, Hee-Jin; Bae, Sung-Jin; Kim, Keuk-Jun; Kim, Cheorl-Ho; Joo, Myungsoo; Ha, Ki-Tae

    2016-07-29

    Ambient cold temperature, as an abiotic stress, regulates the survival, stability, transmission, and infection of pathogens. However, the effect of cold temperature on the host receptivity to the pathogens has not been fully studied. In this study, the expression of terminal α-2,3- and α-2,6-sialic acids were increased in murine lung tissues, especially bronchial epithelium, by exposure to cold condition. The expression of several sialyltransferases were also increased by exposure to cold temperature. Furthermore, in human bronchial epithelial BEAS-2B cells, the expressions of α-2,3- and α-2,6-sialic acids, and mRNA levels of sialyltransferases were increased in the low temperature condition at 33 °C. On the other hand, the treatment of Lith-Gly, a sialyltransferase inhibitor, blocked the cold-induced expression of sialic acids on surface of BEAS-2B cells. The binding of influenza H1N1 hemagglutinin (HA) toward BEAS-2B cells cultured at low temperature condition was increased, compared to 37 °C. In contrast, the cold-increased HA binding was blocked by treatment of lithocholicglycine and sialyl-N-acetyl-D-lactosamines harboring α-2,3- and α-2,6-sialyl motive. These results suggest that the host receptivity to virus at cold temperature results from the expressions of α-2,3- and α-2,6-sialic acids through the regulation of sialyltransferase expression. PMID:27181350

  2. Review of Microbial Responses to Abiotic Environmental Factors in the Context of the Proposed Yucca Mountain Repository

    SciTech Connect

    Meike, A.; Stroes-Gascoyne, S.

    2000-08-01

    A workshop on Microbial Activities at Yucca Mountain (May 1995, Lafayette, CA) was held with the intention to compile information on all pertinent aspects of microbial activity for application to a potential repository at Yucca Mountain. The findings of this workshop set off a number of efforts intended to eventually incorporate the impacts of microbial behavior into performance assessment models. One effort was to expand an existing modeling approach to include the distinctive characteristics of a repository at Yucca Mountain (e.g., unsaturated conditions and a significant thermal load). At the same time, a number of experimental studies were initiated as well as a compilation of relevant literature to more thoroughly study the physical, chemical and biological parameters that would affect microbial activity under Yucca Mountain-like conditions. This literature search (completed in 1996) is the subject of the present document. The collected literature can be divided into four categories: (1) abiotic factors, (2) community dynamics and in-situ considerations, (3) nutrient considerations and (4) transport of radionuclides. The complete bibliography represents a considerable resource, but is too large to be discussed in one document. Therefore, the present report focuses on the first category, abiotic factors, and a discussion of these factors in order to facilitate the development of a model for Yucca Mountain.

  3. Abiotic factors control invasion by Argentine ants at the community scale.

    PubMed

    Menke, Sean B; Holway, David A

    2006-03-01

    1. A prominent and unresolved question in ecology concerns why communities differ in their susceptibility to invasion. While studies often emphasize biotic resistance, it is less widely appreciated how the physical environment affects community vulnerability to invasion. 2. In this study we performed field experiments to test how abiotic variation directly and indirectly influences the extent to which Linepithema humile Mayr (Argentine ants) invade seasonally dry environments in southern California. 3. In controlled and replicated experiments involving drip irrigation, we demonstrate (i) that elevated levels of soil moisture increased both the abundance of Argentine ants and their ability to invade native ant communities and (ii) that cessation of irrigation caused declines in the abundance of Argentine ants and led to their withdrawal from previously occupied areas. 4. Because drip irrigation stimulated plant growth, in an additional experiment we manipulated both soil moisture and plant cover to assess the direct vs. indirect effects of added water on the abundance of L. humile. 5. Local abundance of Argentine ants increased in irrigated plots but was 38% higher in irrigated plots with plants compared to irrigated plots where plant growth was suppressed. The results of this experiment thus argue for a direct role of soil moisture in influencing Argentine ant abundance but suggest that that the indirect effects of added water may also be important. 6. Our study illustrates more generally that fine-scale variation in the physical environment can control whether communities become invaded by non-native species and suggests that an understanding of community susceptibility to invasion will be improved by a better appreciation of interactions between the biotic and abiotic environment. PMID:16637990

  4. The Novel Wheat Transcription Factor TaNAC47 Enhances Multiple Abiotic Stress Tolerances in Transgenic Plants

    PubMed Central

    Zhang, Lina; Zhang, Lichao; Xia, Chuan; Zhao, Guangyao; Jia, Jizeng; Kong, Xiuying

    2016-01-01

    NAC transcription factors play diverse roles in plant development and responses to abiotic stresses. However, the biological roles of NAC family members in wheat are not well understood. Here, we reported the isolation and functional characterization of a novel wheat TaNAC47 gene. TaNAC47 encoded protein, localizing in the nucleus, is able to bind to the ABRE cis-element and transactivate transcription in yeast, suggesting that it likely functions as a transcriptional activator. We also showed that TaNAC47 is differentially expressed in different tissues, and its expression was induced by the stress treatments of salt, cold, polyethylene glycol and exogenous abscisic acid. Furthermore, overexpression of TaNAC47 in Arabidopsis resulted in ABA hypersensitivity and enhancing tolerance of transgenic plants to drought, salt, and freezing stresses. Strikingly, overexpression of TaNAC47 was found to activate the expression of downstream genes and change several physiological indices that may enable transgenic plants to overcome unfavorable environments. Taken together, these results uncovered an important role of wheat TaNAC47 gene in response to ABA and abiotic stresses. PMID:26834757

  5. Genome-wide characterization and analysis of bZIP transcription factor gene family related to abiotic stress in cassava.

    PubMed

    Hu, Wei; Yang, Hubiao; Yan, Yan; Wei, Yunxie; Tie, Weiwei; Ding, Zehong; Zuo, Jiao; Peng, Ming; Li, Kaimian

    2016-01-01

    The basic leucine zipper (bZIP) transcription factor family plays crucial roles in various aspects of biological processes. Currently, no information is available regarding the bZIP family in the important tropical crop cassava. Herein, 77 bZIP genes were identified from cassava. Evolutionary analysis indicated that MebZIPs could be divided into 10 subfamilies, which was further supported by conserved motif and gene structure analyses. Global expression analysis suggested that MebZIPs showed similar or distinct expression patterns in different tissues between cultivated variety and wild subspecies. Transcriptome analysis of three cassava genotypes revealed that many MebZIP genes were activated by drought in the root of W14 subspecies, indicating the involvement of these genes in the strong resistance of cassava to drought. Expression analysis of selected MebZIP genes in response to osmotic, salt, cold, ABA, and H2O2 suggested that they might participate in distinct signaling pathways. Our systematic analysis of MebZIPs reveals constitutive, tissue-specific and abiotic stress-responsive candidate MebZIP genes for further functional characterization in planta, yields new insights into transcriptional regulation of MebZIP genes, and lays a foundation for understanding of bZIP-mediated abiotic stress response. PMID:26947924

  6. Genome-wide characterization and analysis of bZIP transcription factor gene family related to abiotic stress in cassava

    PubMed Central

    Hu, Wei; Yang, Hubiao; Yan, Yan; Wei, Yunxie; Tie, Weiwei; Ding, Zehong; Zuo, Jiao; Peng, Ming; Li, Kaimian

    2016-01-01

    The basic leucine zipper (bZIP) transcription factor family plays crucial roles in various aspects of biological processes. Currently, no information is available regarding the bZIP family in the important tropical crop cassava. Herein, 77 bZIP genes were identified from cassava. Evolutionary analysis indicated that MebZIPs could be divided into 10 subfamilies, which was further supported by conserved motif and gene structure analyses. Global expression analysis suggested that MebZIPs showed similar or distinct expression patterns in different tissues between cultivated variety and wild subspecies. Transcriptome analysis of three cassava genotypes revealed that many MebZIP genes were activated by drought in the root of W14 subspecies, indicating the involvement of these genes in the strong resistance of cassava to drought. Expression analysis of selected MebZIP genes in response to osmotic, salt, cold, ABA, and H2O2 suggested that they might participate in distinct signaling pathways. Our systematic analysis of MebZIPs reveals constitutive, tissue-specific and abiotic stress-responsive candidate MebZIP genes for further functional characterization in planta, yields new insights into transcriptional regulation of MebZIP genes, and lays a foundation for understanding of bZIP-mediated abiotic stress response. PMID:26947924

  7. Heat shock factors in carrot: genome-wide identification, classification, and expression profiles response to abiotic stress.

    PubMed

    Huang, Ying; Li, Meng-Yao; Wang, Feng; Xu, Zhi-Sheng; Huang, Wei; Wang, Guang-Long; Ma, Jing; Xiong, Ai-Sheng

    2015-05-01

    Heat shock factors (HSFs) play key roles in the response to abiotic stress in eukaryotes. In this study, 35 DcHSFs were identified from carrot (Daucus carota L.) based on the carrot genome database. All 35 DcHSFs were divided into three classes (A, B, and C) according to the structure and phylogenetic relationships of four different plants, namely, Arabidopsis thaliana, Vitis vinifera, Brassica rapa, and Oryza sativa. Comparative analysis of algae, gymnosperms, and angiosperms indicated that the numbers of HSF transcription factors were related to the plant's evolution. The expression profiles of five DcHsf genes (DcHsf 01, DcHsf 02, DcHsf 09, DcHsf 10, and DcHsf 16), which selected from each subfamily (A, B, and C), were detected by quantitative real-time PCR under abiotic stresses (cold, heat, high salinity, and drought) in two carrot cultivars, D. carota L. cvs. Kurodagosun and Junchuanhong. The expression levels of DcHsfs were markedly increased by heat stress, except that of DcHsf 10, which was down regulated. The expression profiles of different DcHsfs in the same class also differed under various stress treatments. The expression profiles of these DcHsfs were also different in tissues of two carrot cultivars. This study is the first to identify and characterize the DcHSF family transcription factors in plants of Apiaceae using whole-genome analysis. The results of this study provide an in-depth understanding of the DcHSF family transcription factors' structure, function, and evolution in carrot. PMID:25403331

  8. The role of abiotic factors in the Cambrian Substrate Revolution: A review from the benthic community replacements of West Gondwana

    NASA Astrophysics Data System (ADS)

    Álvaro, J. Javier; Zamora, Samuel; Clausen, Sébastien; Vizcaïno, Daniel; Smith, Andrew B.

    2013-03-01

    The Cambrian Substrate Revolution refers to a substantial and "rapid" change to the nature of marine sedimentary substrates in the early Cambrian and is widely interpreted as a biologically-driven event, a direct response to evolutionary innovations in metazoan burrowing and the development of new shelly faunas. However, abiotic factors such as tectonic and climatic evolution also had the potential to restructure Cambrian substrates, and are here shown to be more plausible drivers of change in the benthic faunas of western Gondwana. The western Mediterranean region underwent a southward drift during Cambrian times, which drove a switch from subtropical carbonates to temperate siliciclastic substrates with short-term episodes of temperate carbonate productivity. As a result, microbial and shelly carbonates disappeared diachronously in a stepwise manner across the lower-middle Cambrian boundary interval. Archaeocyathan-microbial reefs were replaced by chancelloriid-eocrinoid-(spiculate) sponge meadows, in which the stepwise immigration of new echinoderm taxa was primarily controlled by extensional tectonic events, first recorded in rifting settings and later in passive-margin platforms. Availability of new kinds of substrate was thus the primary factor that controlled where and when evolutionary innovations in benthic strategies arose. Examples of this include the early Cambrian colonization of phosphatic hardgrounds and thrombolite crusts by chancelloriids, archaeocyathan and spiculate sponges, and the exploitation by benthos to the increasingly widespread availability of shelly grounds and carbonate firmgrounds by early-diagenetic cementation. A microbial mat/epifaunal antagonistic relationship is demonstrated for echinoderm pelmatozoans based on the non-overlapping palaeogeographic distributions of microbial reefs and mats versus mud-sticker pelmatozoans. Cambrian benthic communities thus evolved in parallel with substrates in response to abiotic factors rather

  9. Temperature dependence of an abiotic glucose/air alkaline fuel cell

    NASA Astrophysics Data System (ADS)

    Orton, Dane; Scott, Daniel

    2015-11-01

    The temperature dependence of a previously developed glucose fuel cell is explored. This cell uses a small molecule dye mediator to transport oxidizable electrons from glucose to a carbon felt anode. This reaction is driven by an air breathing MnO2 cathode. This research investigates how the temperature of the system affects the power production of the fuel cell. Cell performance is observed using either methyl viologen, indigo carmine, trypan blue, or hydroquinone as a mediator at temperatures of 15, 19, 27, 32, 37, 42, and 49 °C. Cyclic voltammetry of the cell anode at the given temperatures with the individual dyes is also presented. The highest power production amongst all of the cells occurs at 32 °C. This occurs with the mediator indigo carmine or with the mediator methyl viologen. These sustained powers are 2.31 mW cm-2 and 2.39 mW cm-2, respectively. This is approximately a 350% increase for these cells compared to their power produced at room temperature. This dramatic increase is likely due to increased solubility of the mediator dye at higher temperatures.

  10. Recent Molecular Advances on Downstream Plant Responses to Abiotic Stress

    PubMed Central

    dos Reis, Sávio Pinho; Lima, Aline Medeiros; de Souza, Cláudia Regina Batista

    2012-01-01

    Abiotic stresses such as extremes of temperature and pH, high salinity and drought, comprise some of the major factors causing extensive losses to crop production worldwide. Understanding how plants respond and adapt at cellular and molecular levels to continuous environmental changes is a pre-requisite for the generation of resistant or tolerant plants to abiotic stresses. In this review we aimed to present the recent advances on mechanisms of downstream plant responses to abiotic stresses and the use of stress-related genes in the development of genetically engineered crops. PMID:22942725

  11. Ostreopsis cf. ovata dynamics in the NW Mediterranean Sea in relation to biotic and abiotic factors.

    PubMed

    Carnicer, Olga; Guallar, Carles; Andree, Karl B; Diogène, Jorge; Fernández-Tejedor, Margarita

    2015-11-01

    An expansion of the distribution of Ostreopsis cf. ovata, a dinoflagellate which produces palytoxin-like compounds, has been reported in recent years. Economical and social interests are affected by blooms, as they are responsible for respiratory and skin problems in humans and may cause damage to marine organisms. In order to identify the most influential environmental factors that trigger proliferations of O. cf. ovata in the area of the adjacent shallow rocky coast of the Ebro Delta (NW Mediterranean Sea) a three-year survey was performed on the metaphytic microalgae community growing on the macrophytes Jania rubens and Corallina elongata. Small-size diatoms were more abundant than dinoflagellates; O. cf. ovata was identified as the only species present from the genus. Seawater temperature was the primary driver defining the ecological niche of O. cf. ovata. Freshwater and groundwater fluxes were more pronounced in southern than in northern sites, which may have resulted in a distinct O. cf. ovata spatial distribution, with the highest records of abundance and more frequent blooms in the north. In consequence, negative correlations between the abundance of O. cf. ovata and nitrate concentrations and significant positive correlation with salinity were observed. The temporal pattern of O. cf. ovata dynamics from mid-July to early-November is probably due to the fact that this species is observed only above a certain threshold temperature of seawater. Metaphytic cells of O. cf. ovata were smaller in the northern site than in the south, possibly as a result of an increase in cell division, coinciding with higher abundance, and this could be an indicator of favorable conditions. Toxicity in planktonic cells was negatively correlated with cell abundance in the water column, achieving maximum concentrations of 25pg. PLTX eqcell(-1). PMID:26365038

  12. Biotic and abiotic factors affecting stemflow variability in downy oak and Scots pine stands in Mediterranean conditions

    NASA Astrophysics Data System (ADS)

    Cayuela, Carles; Garcia-Estringana, Pablo; Latron, Jérôme; Llorens, Pilar

    2015-04-01

    Although stemflow is only a small portion of rainfall, it may represent an important local input of water and nutrients at the plant stem. Previous studies have shown that stemflow has a significant influence on hydrological and biogeochemical processes. Stemflow volume is affected by many biotic factors as species, age, branch or bark characteristics. Moreover, the seasonality of the rainfall regime in Mediterranean areas, which includes both frontal rainfall events and short convective storms, can add complexity to the rainfall-stemflow relationship. This work investigates stemflow dynamics and the influence of biotic and abiotic factors on stemflow rates in two Mediterranean stands during the leafed period - from May to October. The monitored stands are a Downy oak forest (Quercus pubescens) and a Scots pine forest (Pinus sylvestris), both located in the Vallcebre research catchments (NE Spain, 42° 12'N, 1° 49'E). The monitoring design of each plot consists of 7 stemflow rings connected to tipping-buckets, bulk rainfall measured in a nearby clearing and meteorological conditions above the canopies. All data were recorded at 5 min interval. Biometric characteristics of the measured trees were also measured. The analysis of 39 rainfall events (65% smaller than 10 mm) shows that stemflow accounted for less than 1% of the bulk rainfall in both stands. Results also show that, on average, the rainfall amount required for the start of the stemflow and the time delay between the beginning of the precipitation and the start of stemflow are higher in the Downy oak forest. As suggested by stemflow funneling ratios, these differences might be linked to the canopy structure and bark water storage capacity of the trees, indicating that during low magnitude events, oaks have more difficulty to reach storage capacity. The role of other biotic and abiotic parameters on stemflow variability in both stands is still under investigation.

  13. Abiotic stress genes in apple (Malus x domestica): response to low temperature and water deficit

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Survival of many crop species depends on their ability to respond to adverse environmental conditions, including low temperature extremes and drought stress. Although dehydration is a common effect of both freezing stress and drought stress, the distinction between the genetic components that respo...

  14. Silicon isotope fractionation during abiotic silica precipitation at low temperatures: Inferences from flow-through experiments

    NASA Astrophysics Data System (ADS)

    Geilert, Sonja; Vroon, Pieter Z.; Roerdink, Desiree L.; Van Cappellen, Philippe; van Bergen, Manfred J.

    2014-10-01

    Silicon isotopes have considerable potential as proxy for (near-) surface processes and environmental conditions. However, unambiguous interpretations of isotope signatures in natural silica deposits are often hampered by a lack of independent quantitative information on isotopic fractionations operating under the environmental conditions of interest. We performed seeded silica precipitation experiments using flow-through reactors in the 10-60 °C temperature range to alleviate this problem. The principal objective was to quantify the silicon isotope fractionations during controlled precipitation of amorphous silica from a flowing aqueous solution. The experiments were designed to simulate silica deposition induced by a temperature drop, with particular relevance for (near-) surface hydrothermal systems associated with steep temperature gradients. Monitored differences in silicon isotope ratios (30Si/28Si and 29Si/28Si) between input and output solutions demonstrated a systematic sequence in behavior. During an initial time interval, that is, before the reaction system reached steady state, the observed isotope shifts were influenced by dissolution of the seed material, the saturation state of the solution and the specific surface area of the seeds. After reaching steady state, the selective incorporation of silicon isotopes by the solid phase exhibited an explicit temperature dependency: the lighter isotopes were preferentially incorporated, and apparent fractionation magnitudes increased with decreasing temperature. Calculated magnitudes of silicon isotope fractionations between precipitated and dissolved silica (Δ30Si = δ30Siprecipitate (calculated) - δ30Siinput solution) were -2.1‰ at 10 °C, -1.2‰ at 20 °C, -1.0‰ at 30 °C, -0.5‰ at 40 °C, 0.1‰ at 50 °C, and 0.2‰ at 60 °C (s.d. ⩽ 0.6‰, based on replicate experiments). Hence, fractionation was nearly insignificant at temperatures ⩾50 °C. Apart from this relationship with temperature

  15. The SsDREB Transcription Factor from the Succulent Halophyte Suaeda salsa Enhances Abiotic Stress Tolerance in Transgenic Tobacco

    PubMed Central

    Zhang, Xu; Liu, Xiaoxue; Wu, Lei; Yu, Guihong; Wang, Xiue; Ma, Hongxiang

    2015-01-01

    Dehydration-responsive element-binding (DREB) transcription factor (TF) plays a key role for abiotic stress tolerance in plants. In this study, a novel cDNA encoding DREB transcription factor, designated SsDREB, was isolated from succulent halophyte Suaeda salsa. This protein was classified in the A-6 group of DREB subfamily based on multiple sequence alignments and phylogenetic characterization. Yeast one-hybrid assays showed that SsDREB protein specifically binds to the DRE sequence and could activate the expression of reporter genes in yeast, suggesting that the SsDREB protein was a CBF/DREB transcription factor. Real-time RT-PCR showed that SsDREB was significantly induced under salinity and drought stress. Overexpression of SsDREB cDNA in transgenic tobacco plants exhibited an improved salt and drought stress tolerance in comparison to the nontransformed controls. The transgenic plants revealed better growth, higher chlorophyll content, and net photosynthesis rate, as well as higher level of proline and soluble sugars. The semiquantitative PCR of transgenics showed higher expression of stress-responsive genes. These data suggest that the SsDREB transcription factor is involved in the regulation of salt stress tolerance in tobacco by the activation of different downstream gene expression. PMID:26504772

  16. The SsDREB Transcription Factor from the Succulent Halophyte Suaeda salsa Enhances Abiotic Stress Tolerance in Transgenic Tobacco.

    PubMed

    Zhang, Xu; Liu, Xiaoxue; Wu, Lei; Yu, Guihong; Wang, Xiue; Ma, Hongxiang

    2015-01-01

    Dehydration-responsive element-binding (DREB) transcription factor (TF) plays a key role for abiotic stress tolerance in plants. In this study, a novel cDNA encoding DREB transcription factor, designated SsDREB, was isolated from succulent halophyte Suaeda salsa. This protein was classified in the A-6 group of DREB subfamily based on multiple sequence alignments and phylogenetic characterization. Yeast one-hybrid assays showed that SsDREB protein specifically binds to the DRE sequence and could activate the expression of reporter genes in yeast, suggesting that the SsDREB protein was a CBF/DREB transcription factor. Real-time RT-PCR showed that SsDREB was significantly induced under salinity and drought stress. Overexpression of SsDREB cDNA in transgenic tobacco plants exhibited an improved salt and drought stress tolerance in comparison to the nontransformed controls. The transgenic plants revealed better growth, higher chlorophyll content, and net photosynthesis rate, as well as higher level of proline and soluble sugars. The semiquantitative PCR of transgenics showed higher expression of stress-responsive genes. These data suggest that the SsDREB transcription factor is involved in the regulation of salt stress tolerance in tobacco by the activation of different downstream gene expression. PMID:26504772

  17. Characterization of a novel wheat NAC transcription factor gene involved in defense response against stripe rust pathogen infection and abiotic stresses.

    PubMed

    Xia, Ning; Zhang, Gang; Liu, Xin-Ying; Deng, Lin; Cai, Gao-Lei; Zhang, Yi; Wang, Xiao-Jie; Zhao, Jie; Huang, Li-Li; Kang, Zhen-Sheng

    2010-12-01

    Proteins encoded by the NAC gene family constitute one of the largest plant-specific transcription factors, which have been identified to play many important roles in both abiotic and biotic stress adaptation, as well as in plant development regulation. In the current paper, a full-length cDNA sequence of a novel wheat NAC gene, designated as TaNAC4, was isolated using in silico cloning and the reverse transcription PCR (RT-PCR) methods. TaNAC4 sharing high homology with rice OsNAC4 gene was predicted to encode a protein of 308 amino acid residues, which contained a plant-specific NAC domain in the N-terminus. Transient expression analysis indicated that the deduced TaNAC4 protein was localized in the nucleus of onion epidemical cells. Yeast one-hybrid assay revealed that the C-terminal region of the TaNAC4 protein had transcriptional activity. The expression of TaNAC4 was largely higher in the wheat seedling roots, than that in leaves and stems. TaNAC4 transcript in wheat leaves was induced by the infection of strip rust pathogen, and also by exogenous applied methyl jasmonate (MeJA), ABA and ethylene. However, salicylic acid (SA) had no obvious effect on TaNAC4 expression. Environmental stimuli, including high salinity, wounding, and low-temperature also induced TaNAC4 expression. These results indicate that this novel TaNAC4 gene functions as a transcriptional activator involved in wheat response to biotic and abiotic stresses. PMID:20213512

  18. Disentangling the relative importance of host tree community, abiotic environment and spatial factors on ectomycorrhizal fungal assemblages along an elevation gradient.

    PubMed

    Matsuoka, Shunsuke; Mori, Akira S; Kawaguchi, Eri; Hobara, Satoru; Osono, Takashi

    2016-05-01

    Recent studies have shown that changes in community compositions of ectomycorrhizal (ECM) fungi along elevation gradients are mainly affected by changes in host tree communities and/or in abiotic environments. However, few studies have taken the effects of processes related to fungal dispersal (i.e. spatial processes) into account and distinguished the effects of host community, abiotic environment and spatial processes on community composition along elevation gradients. This has left unclear the relative importance of these factors in structuring the ECM community assemblages. To address this, we investigated the community composition of ECM fungi along an elevation gradient in northern Japan with 454 meta-barcoding. We found that the community composition of ECM fungi changed along the elevation and that all three factors jointly affected the compositional changes. We separated the magnitude of importance of the three factors in structuring ECM fungal communities and found that most of the spatial variation in ECM fungal community was explained by host communities and abiotic environments. Our results suggest that while biotic and/or abiotic environments can be important factors in determining the ECM fungal community composition along an elevation gradient, spatial processes may also be a primary determinant. PMID:26917782

  19. A wheat WRKY transcription factor TaWRKY10 confers tolerance to multiple abiotic stresses in transgenic tobacco.

    PubMed

    Wang, Chen; Deng, Pengyi; Chen, Liulin; Wang, Xiatian; Ma, Hui; Hu, Wei; Yao, Ningcong; Feng, Ying; Chai, Ruihong; Yang, Guangxiao; He, Guangyuan

    2013-01-01

    WRKY transcription factors are reported to be involved in defense regulation, stress response and plant growth and development. However, the precise role of WRKY transcription factors in abiotic stress tolerance is not completely understood, especially in crops. In this study, we identified and cloned 10 WRKY genes from genome of wheat (Triticum aestivum L.). TaWRKY10, a gene induced by multiple stresses, was selected for further investigation. TaWRKY10 was upregulated by treatment with polyethylene glycol, NaCl, cold and H2O2. Result of Southern blot indicates that the wheat genome contains three copies of TaWRKY10. The TaWRKY10 protein is localized in the nucleus and functions as a transcriptional activator. Overexpression of TaWRKY10 in tobacco (Nicotiana tabacum L.) resulted in enhanced drought and salt stress tolerance, mainly demonstrated by the transgenic plants exhibiting of increased germination rate, root length, survival rate, and relative water content under these stress conditions. Further investigation showed that transgenic plants also retained higher proline and soluble sugar contents, and lower reactive oxygen species and malonaldehyde contents. Moreover, overexpression of the TaWRKY10 regulated the expression of a series of stress related genes. Taken together, our results indicate that TaWRKY10 functions as a positive factor under drought and salt stresses by regulating the osmotic balance, ROS scavenging and transcription of stress related genes. PMID:23762295

  20. Experimental Study of Abiotic Organic Synthesis at High Temperature and Pressure Conditions: Carbon Isotope and Mineral Surface Characterizations

    NASA Technical Reports Server (NTRS)

    Fu, Qi; Socki, R. A.; Niles, P. B.

    2010-01-01

    Abiotic organic synthesis processes have been proposed as potential mechanisms for methane generation in subseafloor hydrothermal systems on Earth, and on other planets. To better understand the detailed reaction pathways and carbon isotope fractionations in this process under a wide range of physical and chemical conditions, hydrothermal experiments at high temperature (750 C) and pressure (0.55 GPa) were performed using piston cylinder apparatus. Formic acid was used as the source of CO2 and H2, and magnetite was the mineral catalyst. The chemical and carbon isotopic compositions of dissolved organic products were determined by GC-C-MS-IRMS, while organic intermediaries on the mineral catalyst were characterized by Pyrolysis-GC-MS. Among experimental products, dissolved CO2 was the dominant carbon species with a relative abundance of 88 mol%. Dissolved CH4 and C2H6 were also identified with a mole ratio of CH4 over C2H6 of 15:1. No dissolved CO was detected in the experiment, which might be attributable to the loss of H2 through the Au capsule used in the experiments at high temperature and pressure conditions and corresponding conversion of CO to CO2 by the water-gas shift reaction. Carbon isotope results showed that the 13C values of CH4 and C2H6 were -50.3% and -39.3% (V-PDB), respectively. CO2 derived from decarboxylation of formic acid had a (sigma)C-13 value of -19.2%, which was 3.2% heavier than its source, formic acid. The (sigma)C-13 difference between CO2 and CH4 was 31.1%, which was higher than the value of 9.4% calculated from theoretical isotopic equilibrium predictions at experimental conditions, suggesting the presence of a kinetic isotope effect. This number was also higher than the values (4.6 to 27.1%) observed in similar experiments previously performed at 400 C and 50 MPa with longer reaction times. CH4 is 11.0% less enriched in C-13 than C2H6. Alcohols were observed as carbon compounds on magnetite surfaces by Pyrolysis-GC-MS, which confirms

  1. Experimental Study of Abiotic Organic Synthesis at High Temperature and Pressure Conditions: Carbon Isotope and Mineral Surface Characterizations

    NASA Astrophysics Data System (ADS)

    Fu, Q.; Socki, R. A.; Niles, P. B.

    2010-12-01

    Abiotic organic synthesis processes have been proposed as potential mechanisms for methane generation in subseafloor hydrothermal systems on Earth, and on other planets. To better understand the detailed reaction pathways and carbon isotope fractionations in this process under a wide range of physical and chemical conditions, hydrothermal experiments at high temperature (750 °C) and pressure (0.55 GPa) were performed using piston cylinder apparatus. Formic acid was used as the source of CO2 and H2, and magnetite was the mineral catalyst. The chemical and carbon isotopic compositions of dissolved organic products were determined by GC-C-MS-IRMS, while organic intermediaries on the mineral catalyst were characterized by Pyrolysis-GC-MS. Among experimental products, dissolved CO2 was the dominant carbon species with a relative abundance of 88 mol%. Dissolved CH4 and C2H6 were also identified with a mole ratio of CH4 over C2H6 of 15:1. No dissolved CO was detected in the experiment, which might be attributable to the loss of H2 through the Au capsule used in the experiments at high temperature and pressure conditions and corresponding conversion of CO to CO2 by the water-gas shift reaction. Carbon isotope results showed that the δ13C values of CH4 and C2H6 were -50.3‰ and -39.3‰ (V-PDB), respectively. CO2 derived from decarboxylation of formic acid had a δ13C value of -19.2‰, which was 3.2‰ heavier than its source, formic acid. The δ13C difference between CO2 and CH4 was 31.1‰, which was higher than the value of 9.4‰ calculated from theoretical isotopic equilibrium predictions at experimental conditions, suggesting the presence of a kinetic isotope effect. This number was also higher than the values (4.6 to 27.1‰) observed in similar experiments previously performed at 400 °C and 50 MPa with longer reaction times. CH4 is 11.0‰ less enriched in 13C than C2H6. Alcohols were observed as carbon compounds on magnetite surfaces by Pyrolysis-GC-MS, which

  2. Use of a Generalized Additive Model to Investigate Key Abiotic Factors Affecting Microcystin Cellular Quotas in Heavy Bloom Areas of Lake Taihu

    PubMed Central

    Tao, Min; Xie, Ping; Chen, Jun; Qin, Boqiang; Zhang, Dawen; Niu, Yuan; Zhang, Meng; Wang, Qing; Wu, Laiyan

    2012-01-01

    Lake Taihu is the third largest freshwater lake in China and is suffering from serious cyanobacterial blooms with the associated drinking water contamination by microcystin (MC) for millions of citizens. So far, most studies on MCs have been limited to two small bays, while systematic research on the whole lake is lacking. To explain the variations in MC concentrations during cyanobacterial bloom, a large-scale survey at 30 sites across the lake was conducted monthly in 2008. The health risks of MC exposure were high, especially in the northern area. Both Microcystis abundance and MC cellular quotas presented positive correlations with MC concentration in the bloom seasons, suggesting that the toxic risks during Microcystis proliferations were affected by variations in both Microcystis density and MC production per Microcystis cell. Use of a powerful predictive modeling tool named generalized additive model (GAM) helped visualize significant effects of abiotic factors related to carbon fixation and proliferation of Microcystis (conductivity, dissolved inorganic carbon (DIC), water temperature and pH) on MC cellular quotas from recruitment period of Microcystis to the bloom seasons, suggesting the possible use of these factors, in addition to Microcystis abundance, as warning signs to predict toxic events in the future. The interesting relationship between macrophytes and MC cellular quotas of Microcystis (i.e., high MC cellular quotas in the presence of macrophytes) needs further investigation. PMID:22384128

  3. Use of a generalized additive model to investigate key abiotic factors affecting microcystin cellular quotas in heavy bloom areas of Lake Taihu.

    PubMed

    Tao, Min; Xie, Ping; Chen, Jun; Qin, Boqiang; Zhang, Dawen; Niu, Yuan; Zhang, Meng; Wang, Qing; Wu, Laiyan

    2012-01-01

    Lake Taihu is the third largest freshwater lake in China and is suffering from serious cyanobacterial blooms with the associated drinking water contamination by microcystin (MC) for millions of citizens. So far, most studies on MCs have been limited to two small bays, while systematic research on the whole lake is lacking. To explain the variations in MC concentrations during cyanobacterial bloom, a large-scale survey at 30 sites across the lake was conducted monthly in 2008. The health risks of MC exposure were high, especially in the northern area. Both Microcystis abundance and MC cellular quotas presented positive correlations with MC concentration in the bloom seasons, suggesting that the toxic risks during Microcystis proliferations were affected by variations in both Microcystis density and MC production per Microcystis cell. Use of a powerful predictive modeling tool named generalized additive model (GAM) helped visualize significant effects of abiotic factors related to carbon fixation and proliferation of Microcystis (conductivity, dissolved inorganic carbon (DIC), water temperature and pH) on MC cellular quotas from recruitment period of Microcystis to the bloom seasons, suggesting the possible use of these factors, in addition to Microcystis abundance, as warning signs to predict toxic events in the future. The interesting relationship between macrophytes and MC cellular quotas of Microcystis (i.e., high MC cellular quotas in the presence of macrophytes) needs further investigation. PMID:22384128

  4. Effect of abiotic factors on initiation of red flour beetle (Coleoptera: Tenebrionidae) flight

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Traps baited with pheromones are used to monitor the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), populations in flour mills to aid in making pest management decisions, but the factors that influence T. castaneum flight aren’t fully understood. We investigated the impa...

  5. Dual involvement of a Medicago truncatula NAC transcription factor in root abiotic stress response and symbiotic nodule senescence.

    PubMed

    de Zélicourt, Axel; Diet, Anouck; Marion, Jessica; Laffont, Carole; Ariel, Federico; Moison, Michaël; Zahaf, Ons; Crespi, Martin; Gruber, Véronique; Frugier, Florian

    2012-04-01

    Legume crops related to the model plant Medicago truncatula can adapt their root architecture to environmental conditions, both by branching and by establishing a symbiosis with rhizobial bacteria to form nitrogen-fixing nodules. Soil salinity is a major abiotic stress affecting plant yield and root growth. Previous transcriptomic analyses identified several transcription factors linked to the M. truncatula response to salt stress in roots, including NAC (NAM/ATAF/CUC)-encoding genes. Over-expression of one of these transcription factors, MtNAC969, induced formation of a shorter and less-branched root system, whereas RNAi-mediated MtNAC969 inactivation promoted lateral root formation. The altered root system of over-expressing plants was able to maintain its growth under high salinity, and roots in which MtNAC969 was down-regulated showed improved growth under salt stress. Accordingly, expression of salt stress markers was decreased or induced in MtNAC969 over-expressing or RNAi roots, respectively, suggesting a repressive function for this transcription factor in the salt-stress response. Expression of MtNAC969 in central symbiotic nodule tissues was induced by nitrate treatment, and antagonistically affected by salt in roots and nodules, similarly to senescence markers. MtNAC969 RNAi nodules accumulated amyloplasts in the nitrogen-fixing zone, and were prematurely senescent. Therefore, the MtNAC969 transcription factor, which is differentially affected by environmental cues in root and nodules, participates in several pathways controlling adaptation of the M. truncatula root system to the environment. PMID:22098255

  6. Combined Effects of Soil Biotic and Abiotic Factors, Influenced by Sewage Sludge Incorporation, on the Incidence of Corn Stalk Rot

    PubMed Central

    Fortes, Nara Lúcia Perondi; Navas-Cortés, Juan A; Silva, Carlos Alberto; Bettiol, Wagner

    2016-01-01

    The objectives of this study were to evaluate the combined effects of soil biotic and abiotic factors on the incidence of Fusarium corn stalk rot, during four annual incorporations of two types of sewage sludge into soil in a 5-years field assay under tropical conditions and to predict the effects of these variables on the disease. For each type of sewage sludge, the following treatments were included: control with mineral fertilization recommended for corn; control without fertilization; sewage sludge based on the nitrogen concentration that provided the same amount of nitrogen as in the mineral fertilizer treatment; and sewage sludge that provided two, four and eight times the nitrogen concentration recommended for corn. Increasing dosages of both types of sewage sludge incorporated into soil resulted in increased corn stalk rot incidence, being negatively correlated with corn yield. A global analysis highlighted the effect of the year of the experiment, followed by the sewage sludge dosages. The type of sewage sludge did not affect the disease incidence. A multiple logistic model using a stepwise procedure was fitted based on the selection of a model that included the three explanatory parameters for disease incidence: electrical conductivity, magnesium and Fusarium population. In the selected model, the probability of higher disease incidence increased with an increase of these three explanatory parameters. When the explanatory parameters were compared, electrical conductivity presented a dominant effect and was the main variable to predict the probability distribution curves of Fusarium corn stalk rot, after sewage sludge application into the soil. PMID:27176597

  7. Interactions of biotic and abiotic environmental factors in an ectomycorrhizal symbiosis, and the potential for selection mosaics

    PubMed Central

    Piculell, Bridget J; Hoeksema, Jason D; Thompson, John N

    2008-01-01

    Background Geographic selection mosaics, in which species exert different evolutionary impacts on each other in different environments, may drive diversification in coevolving species. We studied the potential for geographic selection mosaics in plant-mycorrhizal interactions by testing whether the interaction between bishop pine (Pinus muricata D. Don) and one of its common ectomycorrhizal fungi (Rhizopogon occidentalis Zeller and Dodge) varies in outcome, when different combinations of plant and fungal genotypes are tested under a range of different abiotic and biotic conditions. Results We used a 2 × 2 × 2 × 2 factorial experiment to test the main and interactive effects of plant lineage (two maternal seed families), fungal lineage (two spore collections), soil type (lab mix or field soil), and non-mycorrhizal microbes (with or without) on the performance of plants and fungi. Ecological outcomes, as assessed by plant and fungal performance, varied widely across experimental environments, including interactions between plant or fungal lineages and soil environmental factors. Conclusion These results show the potential for selection mosaics in plant-mycorrhizal interactions, and indicate that these interactions are likely to coevolve in different ways in different environments, even when initially the genotypes of the interacting species are the same across all environments. Hence, selection mosaics may be equally as effective as genetic differences among populations in driving divergent coevolution among populations of interacting species. PMID:18507825

  8. Combined Effects of Soil Biotic and Abiotic Factors, Influenced by Sewage Sludge Incorporation, on the Incidence of Corn Stalk Rot.

    PubMed

    Ghini, Raquel; Fortes, Nara Lúcia Perondi; Navas-Cortés, Juan A; Silva, Carlos Alberto; Bettiol, Wagner

    2016-01-01

    The objectives of this study were to evaluate the combined effects of soil biotic and abiotic factors on the incidence of Fusarium corn stalk rot, during four annual incorporations of two types of sewage sludge into soil in a 5-years field assay under tropical conditions and to predict the effects of these variables on the disease. For each type of sewage sludge, the following treatments were included: control with mineral fertilization recommended for corn; control without fertilization; sewage sludge based on the nitrogen concentration that provided the same amount of nitrogen as in the mineral fertilizer treatment; and sewage sludge that provided two, four and eight times the nitrogen concentration recommended for corn. Increasing dosages of both types of sewage sludge incorporated into soil resulted in increased corn stalk rot incidence, being negatively correlated with corn yield. A global analysis highlighted the effect of the year of the experiment, followed by the sewage sludge dosages. The type of sewage sludge did not affect the disease incidence. A multiple logistic model using a stepwise procedure was fitted based on the selection of a model that included the three explanatory parameters for disease incidence: electrical conductivity, magnesium and Fusarium population. In the selected model, the probability of higher disease incidence increased with an increase of these three explanatory parameters. When the explanatory parameters were compared, electrical conductivity presented a dominant effect and was the main variable to predict the probability distribution curves of Fusarium corn stalk rot, after sewage sludge application into the soil. PMID:27176597

  9. Cork Oak Vulnerability to Fire: The Role of Bark Harvesting, Tree Characteristics and Abiotic Factors

    PubMed Central

    Catry, Filipe X.; Moreira, Francisco; Pausas, Juli G.; Fernandes, Paulo M.; Rego, Francisco; Cardillo, Enrique; Curt, Thomas

    2012-01-01

    Forest ecosystems where periodical tree bark harvesting is a major economic activity may be particularly vulnerable to disturbances such as fire, since debarking usually reduces tree vigour and protection against external agents. In this paper we asked how cork oak Quercus suber trees respond after wildfires and, in particular, how bark harvesting affects post-fire tree survival and resprouting. We gathered data from 22 wildfires (4585 trees) that occurred in three southern European countries (Portugal, Spain and France), covering a wide range of conditions characteristic of Q. suber ecosystems. Post-fire tree responses (tree mortality, stem mortality and crown resprouting) were examined in relation to management and ecological factors using generalized linear mixed-effects models. Results showed that bark thickness and bark harvesting are major factors affecting resistance of Q. suber to fire. Fire vulnerability was higher for trees with thin bark (young or recently debarked individuals) and decreased with increasing bark thickness until cork was 3–4 cm thick. This bark thickness corresponds to the moment when exploited trees are debarked again, meaning that exploited trees are vulnerable to fire during a longer period. Exploited trees were also more likely to be top-killed than unexploited trees, even for the same bark thickness. Additionally, vulnerability to fire increased with burn severity and with tree diameter, and was higher in trees burned in early summer or located in drier south-facing aspects. We provided tree response models useful to help estimating the impact of fire and to support management decisions. The results suggested that an appropriate management of surface fuels and changes in the bark harvesting regime (e.g. debarking coexisting trees in different years or increasing the harvesting cycle) would decrease vulnerability to fire and contribute to the conservation of cork oak ecosystems. PMID:22787521

  10. The effects of biotic and abiotic factors on the spatial heterogeneity of alpine grassland vegetation at a small scale on the Qinghai-Tibet Plateau (QTP), China.

    PubMed

    Wen, Lu; Dong, Shi Kui; Li, Yuan Yuan; Sherman, Ruth; Shi, Jian Jun; Liu, De Mei; Wang, Yan Long; Ma, Yu Shou; Zhu, Lei

    2013-10-01

    Understanding the complex effects of biotic and abiotic factors on the composition of vegetation is very important for developing and implementing strategies for promoting sustainable grassland development. The vegetation-disturbance-environment relationship was examined in degraded alpine grasslands in the headwater areas of three rivers on the Qinghai-Tibet Plateau in this study. The investigated hypotheses were that (1) the heterogeneity of the vegetation of the alpine grassland is due to a combination of biotic and abiotic factors and that (2) at a small scale, biotic factors are more important for the distribution of alpine vegetation. On this basis, four transects were set along altitudinal gradients from 3,770 to 3,890 m on a sunny slope, and four parallel transects were set along altitudinal gradients on a shady slope in alpine grasslands in Guoluo Prefecture of Qinghai Province, China. It was found that biological disturbances were the major forces driving the spatial heterogeneity of the alpine grassland vegetation and abiotic factors were of secondary importance. Heavy grazing and intensive rat activity resulted in increases in unpalatable and poisonous weeds and decreased fine forages in the form of sedges, forbs, and grasses in the vegetation composition. Habitat degradation associated with biological disturbances significantly affected the spatial variation of the alpine grassland vegetation, i.e., more pioneer plants of poisonous or unpalatable weed species, such as Ligularia virgaurea and Euphorbia fischeriana, were found in bare patches. Environmental/abiotic factors were less important than biological disturbances in affecting the spatial distribution of the alpine grassland vegetation at a small scale. It was concluded that rat control and light grazing should be applied first in implementing restoration strategies. The primary vegetation in lightly grazed and less rat-damaged sites should be regarded as a reference for devising vegetation

  11. De Novo Transcriptome Sequence Assembly and Identification of AP2/ERF Transcription Factor Related to Abiotic Stress in Parsley (Petroselinum crispum)

    PubMed Central

    Wang, Feng; Jiang, Qian; Xu, Zhi-Sheng; Tian, Chang; Xiong, Ai-Sheng

    2014-01-01

    Parsley is an important biennial Apiaceae species that is widely cultivated as herb, spice, and vegetable. Previous studies on parsley principally focused on its physiological and biochemical properties, including phenolic compound and volatile oil contents. However, little is known about the molecular and genetic properties of parsley. In this study, 23,686,707 high-quality reads were obtained and assembled into 81,852 transcripts and 50,161 unigenes for the first time. Functional annotation showed that 30,516 unigenes had sequence similarity to known genes. In addition, 3,244 putative simple sequence repeats were detected in curly parsley. Finally, 1,569 of the identified unigenes belonged to 58 transcription factor families. Various abiotic stresses have a strong detrimental effect on the yield and quality of parsley. AP2/ERF transcription factors have important functions in plant development, hormonal regulation, and abiotic response. A total of 88 putative AP2/ERF factors were identified from the transcriptome sequence of parsley. Seven AP2/ERF transcription factors were selected in this study to analyze the expression profiles of parsley under different abiotic stresses. Our data provide a potentially valuable resource that can be used for intensive parsley research. PMID:25268141

  12. Global analysis of WRKY transcription factor superfamily in Setaria identifies potential candidates involved in abiotic stress signaling

    PubMed Central

    Muthamilarasan, Mehanathan; Bonthala, Venkata S.; Khandelwal, Rohit; Jaishankar, Jananee; Shweta, Shweta; Nawaz, Kashif; Prasad, Manoj

    2015-01-01

    Transcription factors (TFs) are major players in stress signaling and constitute an integral part of signaling networks. Among the major TFs, WRKY proteins play pivotal roles in regulation of transcriptional reprogramming associated with stress responses. In view of this, genome- and transcriptome-wide identification of WRKY TF family was performed in the C4model plants, Setaria italica (SiWRKY) and S. viridis (SvWRKY), respectively. The study identified 105 SiWRKY and 44 SvWRKY proteins that were computationally analyzed for their physicochemical properties. Sequence alignment and phylogenetic analysis classified these proteins into three major groups, namely I, II, and III with majority of WRKY proteins belonging to group II (53 SiWRKY and 23 SvWRKY), followed by group III (39 SiWRKY and 11 SvWRKY) and group I (10 SiWRKY and 6 SvWRKY). Group II proteins were further classified into 5 subgroups (IIa to IIe) based on their phylogeny. Domain analysis showed the presence of WRKY motif and zinc finger-like structures in these proteins along with additional domains in a few proteins. All SiWRKY genes were physically mapped on the S. italica genome and their duplication analysis revealed that 10 and 8 gene pairs underwent tandem and segmental duplications, respectively. Comparative mapping of SiWRKY and SvWRKY genes in related C4 panicoid genomes demonstrated the orthologous relationships between these genomes. In silico expression analysis of SiWRKY and SvWRKY genes showed their differential expression patterns in different tissues and stress conditions. Expression profiling of candidate SiWRKY genes in response to stress (dehydration and salinity) and hormone treatments (abscisic acid, salicylic acid, and methyl jasmonate) suggested the putative involvement of SiWRKY066 and SiWRKY082 in stress and hormone signaling. These genes could be potential candidates for further characterization to delineate their functional roles in abiotic stress signaling. PMID:26635818

  13. C2H2 type of zinc finger transcription factors in foxtail millet define response to abiotic stresses.

    PubMed

    Muthamilarasan, Mehanathan; Bonthala, Venkata Suresh; Mishra, Awdhesh Kumar; Khandelwal, Rohit; Khan, Yusuf; Roy, Riti; Prasad, Manoj

    2014-09-01

    C2H2 type of zinc finger transcription factors (TFs) play crucial roles in plant stress response and hormone signal transduction. Hence considering its importance, genome-wide investigation and characterization of C2H2 zinc finger proteins were performed in Arabidopsis, rice and poplar but no such study was conducted in foxtail millet which is a C4 Panicoid model crop well known for its abiotic stress tolerance. The present study identified 124 C2H2-type zinc finger TFs in foxtail millet (SiC2H2) and physically mapped them onto the genome. The gene duplication analysis revealed that SiC2H2s primarily expanded in the genome through tandem duplication. The phylogenetic tree classified these TFs into five groups (I-V). Further, miRNAs targeting SiC2H2 transcripts in foxtail millet were identified. Heat map demonstrated differential and tissue-specific expression patterns of these SiC2H2 genes. Comparative physical mapping between foxtail millet SiC2H2 genes and its orthologs of sorghum, maize and rice revealed the evolutionary relationships of C2H2 type of zinc finger TFs. The duplication and divergence data provided novel insight into the evolutionary aspects of these TFs in foxtail millet and related grass species. Expression profiling of candidate SiC2H2 genes in response to salinity, dehydration and cold stress showed differential expression pattern of these genes at different time points of stresses. PMID:24915771

  14. Global analysis of WRKY transcription factor superfamily in Setaria identifies potential candidates involved in abiotic stress signaling.

    PubMed

    Muthamilarasan, Mehanathan; Bonthala, Venkata S; Khandelwal, Rohit; Jaishankar, Jananee; Shweta, Shweta; Nawaz, Kashif; Prasad, Manoj

    2015-01-01

    Transcription factors (TFs) are major players in stress signaling and constitute an integral part of signaling networks. Among the major TFs, WRKY proteins play pivotal roles in regulation of transcriptional reprogramming associated with stress responses. In view of this, genome- and transcriptome-wide identification of WRKY TF family was performed in the C4model plants, Setaria italica (SiWRKY) and S. viridis (SvWRKY), respectively. The study identified 105 SiWRKY and 44 SvWRKY proteins that were computationally analyzed for their physicochemical properties. Sequence alignment and phylogenetic analysis classified these proteins into three major groups, namely I, II, and III with majority of WRKY proteins belonging to group II (53 SiWRKY and 23 SvWRKY), followed by group III (39 SiWRKY and 11 SvWRKY) and group I (10 SiWRKY and 6 SvWRKY). Group II proteins were further classified into 5 subgroups (IIa to IIe) based on their phylogeny. Domain analysis showed the presence of WRKY motif and zinc finger-like structures in these proteins along with additional domains in a few proteins. All SiWRKY genes were physically mapped on the S. italica genome and their duplication analysis revealed that 10 and 8 gene pairs underwent tandem and segmental duplications, respectively. Comparative mapping of SiWRKY and SvWRKY genes in related C4 panicoid genomes demonstrated the orthologous relationships between these genomes. In silico expression analysis of SiWRKY and SvWRKY genes showed their differential expression patterns in different tissues and stress conditions. Expression profiling of candidate SiWRKY genes in response to stress (dehydration and salinity) and hormone treatments (abscisic acid, salicylic acid, and methyl jasmonate) suggested the putative involvement of SiWRKY066 and SiWRKY082 in stress and hormone signaling. These genes could be potential candidates for further characterization to delineate their functional roles in abiotic stress signaling. PMID:26635818

  15. Disentangling effects of abiotic factors and biotic interactions on cross-taxon congruence in species turnover patterns of plants, moths and beetles

    PubMed Central

    Duan, Meichun; Liu, Yunhui; Yu, Zhenrong; Baudry, Jacques; Li, Liangtao; Wang, Changliu; Axmacher, Jan C.

    2016-01-01

    High cross-taxon congruence in species diversity patterns is essential for the use of surrogate taxa in biodiversity conservation, but presence and strength of congruence in species turnover patterns, and the relative contributions of abiotic environmental factors and biotic interaction towards this congruence, remain poorly understood. In our study, we used variation partitioning in multiple regressions to quantify cross-taxon congruence in community dissimilarities of vascular plants, geometrid and arciinid moths and carabid beetles, subsequently investigating their respective underpinning by abiotic factors and biotic interactions. Significant cross-taxon congruence observed across all taxon pairs was linked to their similar responses towards elevation change. Changes in the vegetation composition were closely linked to carabid turnover, with vegetation structure and associated microclimatic conditions proposed causes of this link. In contrast, moth assemblages appeared to be dominated by generalist species whose turnover was weakly associated with vegetation changes. Overall, abiotic factors exerted a stronger influence on cross-taxon congruence across our study sites than biotic interactions. The weak congruence in turnover observed particularly between plants and moths highlights the importance of multi-taxon approaches based on groupings of taxa with similar turnovers, rather than the use of single surrogate taxa or environmental proxies, in biodiversity assessments. PMID:27032533

  16. Disentangling effects of abiotic factors and biotic interactions on cross-taxon congruence in species turnover patterns of plants, moths and beetles.

    PubMed

    Duan, Meichun; Liu, Yunhui; Yu, Zhenrong; Baudry, Jacques; Li, Liangtao; Wang, Changliu; Axmacher, Jan C

    2016-01-01

    High cross-taxon congruence in species diversity patterns is essential for the use of surrogate taxa in biodiversity conservation, but presence and strength of congruence in species turnover patterns, and the relative contributions of abiotic environmental factors and biotic interaction towards this congruence, remain poorly understood. In our study, we used variation partitioning in multiple regressions to quantify cross-taxon congruence in community dissimilarities of vascular plants, geometrid and arciinid moths and carabid beetles, subsequently investigating their respective underpinning by abiotic factors and biotic interactions. Significant cross-taxon congruence observed across all taxon pairs was linked to their similar responses towards elevation change. Changes in the vegetation composition were closely linked to carabid turnover, with vegetation structure and associated microclimatic conditions proposed causes of this link. In contrast, moth assemblages appeared to be dominated by generalist species whose turnover was weakly associated with vegetation changes. Overall, abiotic factors exerted a stronger influence on cross-taxon congruence across our study sites than biotic interactions. The weak congruence in turnover observed particularly between plants and moths highlights the importance of multi-taxon approaches based on groupings of taxa with similar turnovers, rather than the use of single surrogate taxa or environmental proxies, in biodiversity assessments. PMID:27032533

  17. Abiotic methane flux from the Chimaera seep and Tekirova ophiolites (Turkey): Understanding gas exhalation from low temperature serpentinization and implications for Mars

    NASA Astrophysics Data System (ADS)

    Etiope, Giuseppe; Schoell, Martin; Hosgörmez, Hakan

    2011-10-01

    The emission of abiotic methane (CH 4) into the atmosphere from low temperature serpentinization in ophiolitic rocks is documented to date only in four countries, the Philippines, Oman, New Zealand, and Turkey. Serpentinization produces large amounts of hydrogen (H 2) which in theory may react with CO 2 or CO to form hydrocarbons (Fischer-Tropsch Type synthesis, FTT). Similar mechanisms have been invoked to explain the CH 4 detected on Mars, so that understanding flux and exhalation modality of ophiolitic gas on Earth may contribute to decipher the potential degassing on Mars. This work reports the first direct measurements of gas (CH 4, CO 2) flux ever done on onshore ophiolites with present-day serpentinization. We investigated the Tekirova ophiolites at Çirali, in Turkey, hosting the Chimaera seep, a system of gas vents issuing from fractures in a 5000 m 2 wide ophiolite outcrop. At this site at least 150-190 t of CH 4 is annually released into the atmosphere. The molecular and isotopic compositions of C 1-C 5 alkanes, CO 2, and N 2 combined with source rock maturity data and thermogenic gas formation modelling suggested a dominant abiotic component (~ 80-90%) mixed with thermogenic gas. Abiotic H 2-rich gas is likely formed at temperatures below 50 °C, suggested by the low deuterium/hydrogen isotopic ratio of H 2 (δD H2: - 720‰), consistent with the low geothermal gradient of the area. Abiotic gas synthesis must be very fast and effective in continuously producing an amount of gas equivalent to the long-lasting (> 2 millennia) emission of > 100 t CH 4 yr - 1 , otherwise pressurised gas accumulation must exist. Over the same ophiolitic formation, 3 km away from Chimaera, we detected an invisible microseepage of abiotic CH 4 with fluxes from 0.07 to 1 g m - 2 d - 1 . On Mars similar fluxes could be able to sustain the CH 4 plume apparently recognised in the Northern Summer 2003 (10 4 or 10 5 t yr - 1 ) over the wide olivine bedrock and outcrops of hydrated

  18. Abiotic origin of biopolymers

    NASA Technical Reports Server (NTRS)

    Oro, J.; Stephen-Sherwood, E.

    1976-01-01

    A variety of methods have been investigated in different laboratories for the polymerization of amino acids and nucleotides under abiotic conditions. They include (1) thermal polymerization; (2) direct polymerization of certain amino acid nitriles, amides, or esters; (3) polymerization using polyphosphate esters; (4) polymerization under aqueous or drying conditions at moderate temperatures using a variety of simple catalysts or condensing agents like cyanamide, dicyandiamide, or imidazole; and (5) polymerization under similar mild conditions but employing activated monomers or abiotically synthesized high-energy compounds such as adenosine 5'-triphosphate (ATP). The role and significance of these methods for the synthesis of oligopeptides and oligonucleotides under possible primitive-earth conditions is evaluated. It is concluded that the more recent approach involving chemical processes similar to those used by contemporary living organisms appears to offer a reasonable solution to the prebiotic synthesis of these biopolymers.

  19. Plant available silicon in South-east Asian rice paddy soils - relevance of agricultural practice and of abiotic factors

    NASA Astrophysics Data System (ADS)

    Marxen, A.; Klotzbücher, T.; Vetterlein, D.; Jahn, R.

    2012-12-01

    Background Silicon (Si) plays a crucial role in rice production. Si content of rice plants exceeds the content of other major nutrients such as nitrogen, phosphorous or potassium. Recent studies showed that in some environments external supply of Si can enhance the growth of rice plants. Rice plants express specific Si transporters to absorb Si from soil solutions in form of silicic acid, which precipitates in tissue cells forming amorphous silica bodies, called phytoliths. The phytoliths are returned to soils with plant residues. They might be a main source of plant available silicic acid in soils. Aims In this study we assess the effects of rice paddy cultivation on the stocks of `reactive` Si fractions in mineral topsoils of rice paddy fields in contrasting landscapes. The `reactive` Si fractions are presumed to determine the release of plant-available silicic acid in soils. We consider the relevance of abiotic factors (mineral assemblage; soil weathering status) and agricultural practice for these fractions. Agricultural practices, which were assumed to affect the stocks of `reactive` Si were (i) the usage of different rice varieties (which might differ in Si demand), (ii) straw residue management (i.e., whether straw residues are returned to the fields or removed and used e.g. as fodder), and (iii) yield level and number of crops per year. Material and methods Soils (top horizon of about 0-20 cm depth) were sampled from rice paddy fields in 2 mountainous and 5 lowland landscapes of contrasting geologic conditions in Vietnam and the Philippines. Ten paddy fields were sampled per landscape. The rice paddy management within landscapes differed when different farmers and/or communities managed the fields. We analysed the following fractions of `reactive` Si in the soils: acetate-extractable Si (dissolved and easily exchangeable Si), phosphate-extractable Si (adsorbed Si), oxalate extractable Si (Si associated with poorly-ordered sesquioxides), NaOH extractable Si

  20. FATE OF FENTHION IN SALT-MARSH ENVIRONMENTS: 1. FACTORS AFFECTING BIOTIC AND ABIOTIC DEGRADATION RATES IN WATER AND SEDIMENT

    EPA Science Inventory

    Fenthion (Baytex), an organophosphate insecticide, is frequently applied to salt-marsh environments to control mosquitoes. hake-flask tests were used to study rates of abiotic and biotic degradation of fenthion and the environmental parameters that affect these rates. Water or wa...

  1. mRNA biogenesis-related helicase eIF4AIII from Arabidopsis thaliana is an important factor for abiotic stress adaptation.

    PubMed

    Pascuan, Cecilia; Frare, Romina; Alleva, Karina; Ayub, Nicolás Daniel; Soto, Gabriela

    2016-05-01

    Similar to other plant species, Arabidopsis has a huge repertoire of predicted helicases, including the eIF4AIII factor, a putative component of the exon junction complex related to mRNA biogenesis. In this article, we integrated evolutionary and functional approaches to have a better understanding of eIF4AIII function in plants. Phylogenetic analysis showed that the mRNA biogenesis-related helicase eIF4AIII is the ortholog of the stress-related helicases PDH45 from Pisum sativum and MH1 from Medicago sativa, suggesting evolutionary and probably functional equivalences between mRNA biogenesis and stress-related plant helicases. Molecular and genetic analyses confirmed the relevance of eIF4AIII during abiotic stress adaptation in Arabidopsis. Therefore, in addition to its function in mRNA biogenesis, eIF4AIII can play a role in abiotic stress adaptation. PMID:26883227

  2. Biotic vs. abiotic control of decomposition: a comparison of the effects of simulated extinctions and changes in temperature.

    PubMed

    Boyero, Luz; Cardinale, Bradley J; Bastian, Mikis; Pearson, Richard G

    2014-01-01

    The loss of species is known to have significant effects on ecosystem functioning, but only recently has it been recognized that species loss might rival the effects of other forms of environmental change on ecosystem processes. There is a need for experimental studies that explicitly manipulate species richness and environmental factors concurrently to determine their relative impacts on key ecosystem processes such as plant litter decomposition. It is crucial to understand what factors affect the rate of plant litter decomposition and the relative magnitude of such effects because the rate at which plant litter is lost and transformed to other forms of organic and inorganic carbon determines the capacity for carbon storage in ecosystems and the rate at which greenhouse gasses such as carbon dioxide are outgassed. Here we compared how an increase in water temperature of 5°C and loss of detritivorous invertebrate and plant litter species affect decomposition rates in a laboratory experiment simulating stream conditions. Like some prior studies, we found that species identity, rather than species richness per se, is a key driver of decomposition, but additionally we showed that the loss of particular species can equal or exceed temperature change in its impact on decomposition. Our results indicate that the loss of particular species can be as important a driver of decomposition as substantial temperature change, but also that predicting the relative consequences of species loss and other forms of environmental change on decomposition requires knowledge of assemblages and their constituent species' ecology and ecophysiology. PMID:24466351

  3. Kresoxim-methyl primes Medicago truncatula plants against abiotic stress factors via altered reactive oxygen and nitrogen species signalling leading to downstream transcriptional and metabolic readjustment.

    PubMed

    Filippou, Panagiota; Antoniou, Chrystalla; Obata, Toshihiro; Van Der Kelen, Katrien; Harokopos, Vaggelis; Kanetis, Loukas; Aidinis, Vassilis; Van Breusegem, Frank; Fernie, Alisdair R; Fotopoulos, Vasileios

    2016-03-01

    Biotic and abiotic stresses, such as fungal infection and drought, cause major yield losses in modern agriculture. Kresoxim-methyl (KM) belongs to the strobilurins, one of the most important classes of agricultural fungicides displaying a direct effect on several plant physiological and developmental processes. However, the impact of KM treatment on salt and drought stress tolerance is unknown. In this study we demonstrate that KM pre-treatment of Medicago truncatula plants results in increased protection to drought and salt stress. Foliar application with KM prior to stress imposition resulted in improvement of physiological parameters compared with stressed-only plants. This protective effect was further supported by increased proline biosynthesis, modified reactive oxygen and nitrogen species signalling, and attenuation of cellular damage. In addition, comprehensive transcriptome analysis identified a number of transcripts that are differentially accumulating in drought- and salinity-stressed plants (646 and 57, respectively) after KM pre-treatment compared with stressed plants with no KM pre-treatment. Metabolomic analysis suggests that the priming role of KM in drought- and to a lesser extent in salinity-stressed plants can be attributed to the regulation of key metabolites (including sugars and amino acids) resulting in protection against abiotic stress factors. Overall, the present study highlights the potential use of this commonly used fungicide as a priming agent against key abiotic stress conditions. PMID:26712823

  4. Kresoxim-methyl primes Medicago truncatula plants against abiotic stress factors via altered reactive oxygen and nitrogen species signalling leading to downstream transcriptional and metabolic readjustment

    PubMed Central

    Filippou, Panagiota; Antoniou, Chrystalla; Obata, Toshihiro; Van Der Kelen, Katrien; Harokopos, Vaggelis; Kanetis, Loukas; Aidinis, Vassilis; Van Breusegem, Frank; Fernie, Alisdair R; Fotopoulos, Vasileios

    2016-01-01

    Biotic and abiotic stresses, such as fungal infection and drought, cause major yield losses in modern agriculture. Kresoxim-methyl (KM) belongs to the strobilurins, one of the most important classes of agricultural fungicides displaying a direct effect on several plant physiological and developmental processes. However, the impact of KM treatment on salt and drought stress tolerance is unknown. In this study we demonstrate that KM pre-treatment of Medicago truncatula plants results in increased protection to drought and salt stress. Foliar application with KM prior to stress imposition resulted in improvement of physiological parameters compared with stressed-only plants. This protective effect was further supported by increased proline biosynthesis, modified reactive oxygen and nitrogen species signalling, and attenuation of cellular damage. In addition, comprehensive transcriptome analysis identified a number of transcripts that are differentially accumulating in drought- and salinity-stressed plants (646 and 57, respectively) after KM pre-treatment compared with stressed plants with no KM pre-treatment. Metabolomic analysis suggests that the priming role of KM in drought- and to a lesser extent in salinity-stressed plants can be attributed to the regulation of key metabolites (including sugars and amino acids) resulting in protection against abiotic stress factors. Overall, the present study highlights the potential use of this commonly used fungicide as a priming agent against key abiotic stress conditions. PMID:26712823

  5. A stress-associated NAC transcription factor (SlNAC35) from tomato plays a positive role in biotic and abiotic stresses.

    PubMed

    Wang, Guodong; Zhang, Song; Ma, Xiaocui; Wang, Yong; Kong, Fanying; Meng, Qingwei

    2016-09-01

    The NAC transcription factor family participates in responses to various kinds of environmental stimuli in plants. Responses of NAC genes to abiotic stresses have been widely studied, but their functions in response to biotic stress are little reported in plants, especially in crops. In the present study, we examined the functions of a novel tomato (Solanum lycopersicum) NAC protein (SlNAC35) in abiotic and biotic stress resistance by using transgenic tobacco. Expression analysis found that SlNAC35 expression was induced by drought stress, salt stress, bacterial pathogen, and signaling molecules, suggesting its involvement in plant responses to biotic and abiotic stimuli. Moreover, transgenic lines exhibited a greater number of lateral roots and longer root length compared with Vec lines (empty vector lines) after drought and salt treatment. These results indicate that overexpression of SlNAC35 promoted root growth and development under drought and salt stresses. Higher expressions of NtARF1, NtARF2 and NtARF8 were observed under drought and salt stresses in transgenic lines, suggesting that overexpression of SlNAC35 promoted growth and development of roots in transgenic lines possibly by involving auxin signaling and by regulating NtARF expression. In addition, SlNAC35 overexpression improved resistance to bacterial pathogen in transgenic tobacco, and reactive oxygen species may be in the upstream of salicylic acid (SA) signaling in transgenic tobacco during defense response. PMID:26991441

  6. Transcriptional profiling of Medicago truncatula under salt stress identified a novel CBF transcription factor MtCBF4 that plays an important role in abiotic stress responses

    PubMed Central

    2011-01-01

    Background Salt stress hinders the growth of plants and reduces crop production worldwide. However, different plant species might possess different adaptive mechanisms to mitigate salt stress. We conducted a detailed pathway analysis of transcriptional dynamics in the roots of Medicago truncatula seedlings under salt stress and selected a transcription factor gene, MtCBF4, for experimental validation. Results A microarray experiment was conducted using root samples collected 6, 24, and 48 h after application of 180 mM NaCl. Analysis of 11 statistically significant expression profiles revealed different behaviors between primary and secondary metabolism pathways in response to external stress. Secondary metabolism that helps to maintain osmotic balance was induced. One of the highly induced transcription factor genes was successfully cloned, and was named MtCBF4. Phylogenetic analysis revealed that MtCBF4, which belongs to the AP2-EREBP transcription factor family, is a novel member of the CBF transcription factor in M. truncatula. MtCBF4 is shown to be a nuclear-localized protein. Expression of MtCBF4 in M. truncatula was induced by most of the abiotic stresses, including salt, drought, cold, and abscisic acid, suggesting crosstalk between these abiotic stresses. Transgenic Arabidopsis over-expressing MtCBF4 enhanced tolerance to drought and salt stress, and activated expression of downstream genes that contain DRE elements. Over-expression of MtCBF4 in M. truncatula also enhanced salt tolerance and induced expression level of corresponding downstream genes. Conclusion Comprehensive transcriptomic analysis revealed complex mechanisms exist in plants in response to salt stress. The novel transcription factor gene MtCBF4 identified here played an important role in response to abiotic stresses, indicating that it might be a good candidate gene for genetic improvement to produce stress-tolerant plants. PMID:21718548

  7. Using vegetation model-to-data comparisons to test the role of abiotic factors in the Neogene and Quaternary origins of modern C4 grasslands

    NASA Astrophysics Data System (ADS)

    Fox, D. L.; Strömberg, C.; Pau, S.; Taylor, L.; Lehmann, C.; Osborne, C.; Beerling, D. J.; Still, C. J.

    2014-12-01

    ) of multiple plant functional types (C3 and C4 grasses, evergreen and deciduous trees). Statistical comparisons of the isotopic and paleobotanical databases with the paleoclimate and vegetation model outputs allows us to assess the possible role of abiotic factors in the evolution of modern C4 grasslands during the late Neogene.

  8. Direct and indirect effects of climate on demography and early growth of Pinus sylvestris at the rear edge: changing roles of biotic and abiotic factors.

    PubMed

    Benavides, Raquel; Rabasa, Sonia G; Granda, Elena; Escudero, Adrián; Hódar, José A; Martínez-Vilalta, Jordi; Rincón, Ana M; Zamora, Regino; Valladares, Fernando

    2013-01-01

    Global change triggers shifts in forest composition, with warming and aridification being particularly threatening for the populations located at the rear edge of the species distributions. This is the case of Scots pine (Pinus sylvestris) in the Mediterranean Basin where uncertainties in relation to its dynamics under these changing scenarios are still high. We analysed the relative effect of climate on the recruitment patterns of Scots pine and its interactions with local biotic and abiotic variables at different spatial scales. Number of seedlings and saplings was surveyed, and their annual shoot growth measured in 96 plots located across altitudinal gradients in three different regions in the Iberian Peninsula. We found a significant influence of climate on demography and performance of recruits, with a non-linear effect of temperature on the presence of juveniles, and a positive effect of precipitation on their survival. Abundance of juveniles of P. sylvestris that underwent their first summer drought was skewed towards higher altitudes than the altitudinal mean range of the conspecific adults and the optimum elevation for seedlings' emergence. At local level, light availability did not influence juveniles' density, but it enhanced their growth. Biotic interactions were found between juveniles and the herb cover (competition) and between the number of newly emerged seedlings and shrubs (facilitation). Results also highlighted the indirect effect that climate exerts over the local factors, modulating the interactions with the pre-existing vegetation that were more evident at more stressful sites. This multiscale approach improves our understanding of the dynamics of these marginal populations and some management criteria can be inferred to boost their conservation under the current global warming. PMID:23555794

  9. Direct and Indirect Effects of Climate on Demography and Early Growth of Pinus sylvestris at the Rear Edge: Changing Roles of Biotic and Abiotic Factors

    PubMed Central

    Benavides, Raquel; Rabasa, Sonia G.; Granda, Elena; Escudero, Adrián; Hódar, José A.; Martínez-Vilalta, Jordi; Rincón, Ana M.; Zamora, Regino; Valladares, Fernando

    2013-01-01

    Global change triggers shifts in forest composition, with warming and aridification being particularly threatening for the populations located at the rear edge of the species distributions. This is the case of Scots pine (Pinus sylvestris) in the Mediterranean Basin where uncertainties in relation to its dynamics under these changing scenarios are still high. We analysed the relative effect of climate on the recruitment patterns of Scots pine and its interactions with local biotic and abiotic variables at different spatial scales. Number of seedlings and saplings was surveyed, and their annual shoot growth measured in 96 plots located across altitudinal gradients in three different regions in the Iberian Peninsula. We found a significant influence of climate on demography and performance of recruits, with a non-linear effect of temperature on the presence of juveniles, and a positive effect of precipitation on their survival. Abundance of juveniles of P. sylvestris that underwent their first summer drought was skewed towards higher altitudes than the altitudinal mean range of the conspecific adults and the optimum elevation for seedlings' emergence. At local level, light availability did not influence juveniles' density, but it enhanced their growth. Biotic interactions were found between juveniles and the herb cover (competition) and between the number of newly emerged seedlings and shrubs (facilitation). Results also highlighted the indirect effect that climate exerts over the local factors, modulating the interactions with the pre-existing vegetation that were more evident at more stressful sites. This multiscale approach improves our understanding of the dynamics of these marginal populations and some management criteria can be inferred to boost their conservation under the current global warming. PMID:23555794

  10. The Alfin-like homeodomain finger protein AL5 suppresses multiple negative factors to confer abiotic stress tolerance in Arabidopsis.

    PubMed

    Wei, Wei; Zhang, Yu-Qin; Tao, Jian-Jun; Chen, Hao-Wei; Li, Qing-Tian; Zhang, Wan-Ke; Ma, Biao; Lin, Qing; Zhang, Jin-Song; Chen, Shou-Yi

    2015-03-01

    Plant homeodomain (PHD) finger proteins affect processes of growth and development by changing transcription and reading epigenetic histone modifications, but their functions in abiotic stress responses remain largely unclear. Here we characterized seven Arabidopsis thaliana Alfin1-like PHD finger proteins (ALs) in terms of the responses to abiotic stresses. ALs localized to the nucleus and repressed transcription. Except AL6, all the ALs bound to G-rich elements. Mutations of the amino acids at positions 34 and 35 in AL6 caused loss of ability to bind to G-rich elements. Expression of the AL genes responded differentially to osmotic stress, salt, cold and abscisic acid treatments. AL5-over-expressing plants showed higher tolerance to salt, drought and freezing stress than Col-0. Consistently, al5 mutants showed reduced stress tolerance. We used ChIP-Seq assays to identify eight direct targets of AL5, and found that AL5 binds to the promoter regions of these genes. Knockout mutants of five of these target genes exhibited varying tolerances to stresses. These results indicate that AL5 inhibits multiple signaling pathways to confer stress tolerance. Our study sheds light on mechanisms of AL5-mediated signaling in abiotic stress responses, and provides tools for improvement of stress tolerance in crop plants. PMID:25619813

  11. The influence of top-down, bottom-up and abiotic factors on the moose (Alces alces) population of Isle Royale.

    PubMed

    Vucetich, John A; Peterson, Rolf O

    2004-01-22

    Long-term, concurrent measurement of population dynamics and associated top-down and bottom-up processes are rare for unmanipulated, terrestrial systems. Here, we analyse populations of moose, their predators (wolves, Canis lupus), their primary winter forage (balsam fir, Abies balsamea) and several climatic variables that were monitored for 40 consecutive years in Isle Royale National Park (544 km2), Lake Superior, USA. We judged the relative importance of top-down, bottom-up and abiotic factors on moose population growth rate by constructing multiple linear regression models, and calculating the proportion of interannual variation in moose population growth rate explained by each factor. Our analysis indicates that more variation in population growth rate is explained by bottom-up than top-down processes, and abiotic factors explain more variation than do bottom-up processes. Surprisingly, winter precipitation did not explain any significant variation in population growth rate. Like that detected for two Norwegian ungulate populations, the relationship between population growth rate and the North Atlantic Oscillation was nonlinear. Although this analysis provides significant insight, much remains unknown: of the models examined, the most parsimonious explain little more than half the variation in moose population growth rate. PMID:15058396

  12. The influence of top-down, bottom-up and abiotic factors on the moose (Alces alces) population of Isle Royale.

    PubMed Central

    Vucetich, John A.; Peterson, Rolf O.

    2004-01-01

    Long-term, concurrent measurement of population dynamics and associated top-down and bottom-up processes are rare for unmanipulated, terrestrial systems. Here, we analyse populations of moose, their predators (wolves, Canis lupus), their primary winter forage (balsam fir, Abies balsamea) and several climatic variables that were monitored for 40 consecutive years in Isle Royale National Park (544 km2), Lake Superior, USA. We judged the relative importance of top-down, bottom-up and abiotic factors on moose population growth rate by constructing multiple linear regression models, and calculating the proportion of interannual variation in moose population growth rate explained by each factor. Our analysis indicates that more variation in population growth rate is explained by bottom-up than top-down processes, and abiotic factors explain more variation than do bottom-up processes. Surprisingly, winter precipitation did not explain any significant variation in population growth rate. Like that detected for two Norwegian ungulate populations, the relationship between population growth rate and the North Atlantic Oscillation was nonlinear. Although this analysis provides significant insight, much remains unknown: of the models examined, the most parsimonious explain little more than half the variation in moose population growth rate. PMID:15058396

  13. Ethylene response factor Sl-ERF.B.3 is responsive to abiotic stresses and mediates salt and cold stress response regulation in tomato.

    PubMed

    Klay, Imen; Pirrello, Julien; Riahi, Leila; Bernadac, Anne; Cherif, Ameur; Bouzayen, Mondher; Bouzid, Sadok

    2014-01-01

    Sl-ERF.B.3 (Solanum lycopersicum ethylene response factor B.3) gene encodes for a tomato transcription factor of the ERF (ethylene responsive factor) family. Our results of real-time RT-PCR showed that Sl-ERF.B.3 is an abiotic stress responsive gene, which is induced by cold, heat, and flooding, but downregulated by salinity and drought. To get more insight into the role of Sl-ERF.B.3 in plant response to separate salinity and cold, a comparative study between wild type and two Sl-ERF.B.3 antisense transgenic tomato lines was achieved. Compared with wild type, Sl-ERF.B.3 antisense transgenic plants exhibited a salt stress dependent growth inhibition. This inhibition was significantly enhanced in shoots but reduced in roots, leading to an increased root to shoot ratio. Furthermore, the cold stress essay clearly revealed that introducing antisense Sl-ERF.B.3 in transgenic tomato plants reduces their cell injury and enhances their tolerance against 14 d of cold stress. All these results suggest that Sl-ERF.B.3 gene is involved in plant response to abiotic stresses and may play a role in the layout of stress symptoms under cold stress and in growth regulation under salinity. PMID:25215313

  14. Review of recent transgenic studies on abiotic stress tolerance and future molecular breeding in potato

    PubMed Central

    Kikuchi, Akira; Huynh, Huu Duc; Endo, Tsukasa; Watanabe, Kazuo

    2015-01-01

    Global warming has become a major issue within the last decade. Traditional breeding programs for potato have focused on increasing productivity and quality and disease resistance, thus, modern cultivars have limited tolerance of abiotic stresses. The introgression of abiotic stress tolerance into modern cultivars is essential work for the future. Recently, many studies have investigated abiotic stress using transgenic techniques. This manuscript focuses on the study of abiotic stress, in particular drought, salinity and low temperature, during this century. Dividing studies into these three stress categories for this review was difficult. Thus, based on the study title and the transgene property, transgenic studies were classified into five categories in this review; oxidative scavengers, transcriptional factors, and above three abiotic categories. The review focuses on studies that investigate confer of stress tolerance and the identification of responsible factors, including wild relatives. From a practical application perspective, further evaluation of transgenic potato with abiotic stress tolerance is required. Although potato plants, including wild species, have a large potential for abiotic stress tolerance, exploration of the factors responsible for conferring this tolerance is still developing. Molecular breeding, including genetic engineering and conventional breeding using DNA markers, is expected to develop in the future. PMID:25931983

  15. Marine Invasion in the Mediterranean Sea: The Role of Abiotic Factors When There Is No Biological Resistance

    PubMed Central

    2012-01-01

    The tropical red alga Womersleyella setacea (Rhodomelaceae, Rhodophyta) is causing increasing concern in the Mediterranean Sea because of its invasive behavior. After its introduction it has colonized most Mediterranean areas, but the mechanism underlying its acclimatization and invasion process remains unknown. To understand this process, we decided i) to assess in situ the seasonal biomass and phenological patterns of populations inhabiting the Mediterranean Sea in relation to the main environmental factors, and ii) to experimentally determine if the tolerance of W. setacea to different light and temperature conditions can explain its colonization success, as well as its bathymetric distribution range. The bathymetric distribution, biomass, and phenology of W. setacea were studied at two localities, and related to irradiance and temperature values recorded in situ. Laboratory experiments were set up to study survival, growth and reproduction under contrasting light and temperature conditions in the short, mid, and long term.Results showed that, in the studied area, the bathymetric distribution of W. setacea is restricted to a depth belt between 25 and 40 m deep, reaching maximum biomass values (126 g dw m−2) at 30 m depth. In concordance, although in the short term W. setacea survived and grew in a large range of environmental conditions, its life requirements for the mid and long term were dim light levels and low temperatures. Biomass of Womersleyella setacea did not show any clear seasonal pattern, though minimum values were reported in spring. Reproductive structures were always absent. Bearing in mind that no herbivores feed on Womersleyella setacea and that its thermal preferences are more characteristic of temperate than of tropical seaweeds, low light (50 µmol photon m−2 s−1) and low temperature (12°C) levels are critical for W. setacea survival and growth, thus probably determining its spread and bathymetric distribution across the Mediterranean

  16. Genome Wide Analysis of the Apple MYB Transcription Factor Family Allows the Identification of MdoMYB121 Gene Confering Abiotic Stress Tolerance in Plants

    PubMed Central

    Wang, Rong-Kai; Zhang, Rui-Fen; Hao, Yu-Jin

    2013-01-01

    The MYB proteins comprise one of the largest families of transcription factors (TFs) in plants. Although several MYB genes have been characterized to play roles in secondary metabolism, the MYB family has not yet been identified in apple. In this study, 229 apple MYB genes were identified through a genome-wide analysis and divided into 45 subgroups. A computational analysis was conducted using the apple genomic database to yield a complete overview of the MYB family, including the intron-exon organizations, the sequence features of the MYB DNA-binding domains, the carboxy-terminal motifs, and the chromosomal locations. Subsequently, the expression of 18 MYB genes, including 12 were chosen from stress-related subgroups, while another 6 ones from other subgroups, in response to various abiotic stresses was examined. It was found that several of these MYB genes, particularly MdoMYB121, were induced by multiple stresses. The MdoMYB121 was then further functionally characterized. Its predicted protein was found to be localized in the nucleus. A transgenic analysis indicated that the overexpression of the MdoMYB121 gene remarkably enhanced the tolerance to high salinity, drought, and cold stresses in transgenic tomato and apple plants. Our results indicate that the MYB genes are highly conserved in plant species and that MdoMYB121 can be used as a target gene in genetic engineering approaches to improve the tolerance of plants to multiple abiotic stresses. PMID:23950843

  17. PsAP2 an AP2/ERF family transcription factor from Papaver somniferum enhances abiotic and biotic stress tolerance in transgenic tobacco.

    PubMed

    Mishra, Sonal; Phukan, Ujjal J; Tripathi, Vineeta; Singh, Dhananjay K; Luqman, Suaib; Shukla, Rakesh Kumar

    2015-09-01

    The AP2/ERFs are one of the most important family of transcription factors which regulate multiple responses like stress, metabolism and development in plants. We isolated PsAP2 a novel AP2/ERF from Papaver somniferum which was highly upregulated in response to wounding followed by ethylene, methyl jasmonate and ABA treatment. PsAP2 showed specific binding with both DRE and GCC box elements and it was able to transactivate the reporter genes in yeast. PsAP2 overexpressing transgenic tobacco plants exhibited enhanced tolerance towards both abiotic and biotic stresses . Real time transcript expression analysis showed constitutive upregulation of tobacco Alternative oxidase1a and Myo-inositol-1-phosphate synthase in PsAP2 overexpressing tobacco plants. Further, PsAP2 showed interaction with NtAOX1a promoter in vitro, it also specifically activated the NtAOX1a promoter in yeast and tobacco BY2 cells. The silencing of PsAP2 using VIGS lead to significant reduction in the AOX1 level in P. somniferum. Taken together PsAP2 can directly bind and transcriptionally activate NtAOX1a and its overexpression in tobacco imparted increased tolerance towards both abiotic and biotic stress. PMID:26319514

  18. Biotic and abiotic factors related to lake herring recruitment in the Wisconsin waters of Lake Superior, 1984-1998

    USGS Publications Warehouse

    Hoff, Michael H.

    2004-01-01

    Lake Superior lake herring (Coregonus artedi) recruitment to 13-14 months of age in the Wisconsin waters of Lake Superior varied by a factor of 5,233 during 1984-1998. Management agencies have sought models that accurately predict recruitment, but no satisfactory model had previously been developed. Lake herring recruitment was modeled to determine which factors most explained recruitment variability. The Ricker stock-recruitment model derived from only the paired stock and recruit data explained 35% of the variability in the recruitment data. The functional relationship that explained the greatest amount of recruitment variation (93%) included lake herring stock size, lake trout (Salvelinus namaycush) population size, slimy sculpin (Cottus cognatus) biomass, the interaction of mean daily wind speed in April (month of hatch) and lake herring stock size, and mean air temperature in April (when lake herring are 12-months old). Model results were interpreted to mean that lake herring recruitment was affected negatively by: slimy sculpin predation on lake herring ova; predation on age-0 lake herring by lake trout; and adult cannibalism on lake herring larvae, which was reduced by increased wind speed. April temperature was the variable that explained the least amount of variability in recruitment, but lake herring recruitment was positively affected by a warm April, which shortened winter and apparently reduced first-winter mortality. Stock size caused compensatory, density-dependent mortality on lake herring recruits. Management efforts appear best targeted at stock size protection, and empirical data implies that stock size in the Wisconsin waters of the lake should be maintained at 2.1-15.0 adults/ha in spring, bottom-trawl surveys.

  19. [Factors affecting the temperature of domestic refrigerators].

    PubMed

    Derens, E; Laguerre, O; Palagos, B

    2001-01-01

    A survey was carried out in France in 1999 in order to know the air temperature in domestic refrigerators and the factors which may effect this temperature. Temperatures were recorded at three levels (top, middle and bottom of the refrigerator compartment). A questionnaire was filled to acquire the following information: characteristic of family (number of family members, age, profession, income...), characteristic of refrigerator (trade, type, age, temperature setting, refrigerating type...) and the use condition (room temperature, near by heat source, built in, door opening frequency...). The average temperature of the 119 surveyed refrigerators was 6.6 degrees C. Descriptive analysis and multi dimensional analysis of factors effecting refrigerator temperature were carried out. The classification tree and the segmentation confirm the influence of the use condition (frequency of door opening, temperature setting, near by heat source and built in). There is no direct effect of one factor but the combination of all of them. PMID:11474586

  20. Biotic and abiotic factors affecting the flight activity of Fopius arisanus, an egg-pupal parasitoid of fruit fly pests.

    PubMed

    Rousse, P; Gourdon, F; Roubaud, M; Chiroleu, F; Quilici, S

    2009-06-01

    Climatic conditions and the physiological state of a parasitoid may alter its host selection behavior and thus its efficiency as a biological control agent. We studied the influence of these parameters on the behavior of Fopius arisanus (Sonan), an egg-pupal parasitoid of many Tephritidae. In the first experiment, we assessed in field cage assays the influence of temperature, humidity, light intensity, barometric pressure, and wind speed. Both flight and parasitism were mainly affected by temperature and humidity. However, because these two factors were strongly correlated in our experiments, the direct influence of each one cannot be specified. Flight activity was affected by variations in barometric pressure. In a second set of experiments, we conducted release and recapture assays with dyed insects to determine the influence of sex, mating status, egg load, age, and starvation on attraction toward infested fruit. Males were not attracted, suggesting that fruit are not a mating site. The egg load seemed to be a major parameter of foraging motivation. Finally, we showed that flight activity strongly decreased after 48 h of starvation. We observed a possible switch to food in the foraging motivation of starved females, but this result was impaired by poor recoveries: <10% of released females were recaptured after 96 h of starvation. We finally discuss the importance of these observations on the efficiency of F. arisanus as a biological control agent in tropical humid areas. PMID:19508801

  1. Biotic and abiotic factors influencing the long-term stability of covers on waste rock piles in the uranium mining district of Saxony and Thuringia (Germany)

    SciTech Connect

    Heinze, M.; Koehler, M.; Saenger, H.

    1999-07-01

    This report presents the results of basic investigations of root penetration on various partially covered excavation discard material mounds of the Saxonian-Thuringian uranium mining region (Germany) in comparison to root penetration in autochthonous (native) soils. Bioturbation is an essential, unavoidable impact to consider in addition to root penetration. With increasing age, the functionality of each layer of a cover system becomes diminished through the workings of the local flora and fauna. Pedological cover layers can only temporarily maintain their initial positions and technical functionality. Considering actual prevailing biotic and abiotic influences (e.g., site-specific transpiration rates), the planning and installation of cover systems should take into account (within acceptable balances) factors which are able to at least partially compensate for eventual diminishing of technical functionality.

  2. Spatial patterns of distribution and the influence of seasonal and abiotic factors on demersal ichthyofauna in an estuarine tropical bay.

    PubMed

    da Silva, D R; Paranhos, R; Vianna, M

    2016-07-01

    This study focused on the influence of local-scale environmental factors on key metrics of fish community structure and function at Guanabara Bay, an estuarine system that differs from all other south-western Atlantic estuaries due to the influence of an annual low-intensity upwelling event during late spring and summer, between November and March, when a warm rainy climate prevails. The spatial patterns of the bottom temperature and salinity were more heterogeneous during the rainy season than the dry season, being linked to total precipitation and seasonal oceanographic events. The study identified 130 species and 45 families, placing Guanabara Bay as one of the most species-rich tropical estuarine ecosystems, far exceeding 22 other Brazilian estuaries. These results, in addition to characteristics such as a relatively well-preserved mangrove forest, high productivity and favourable conditions for the growth and reproduction of estuarine species, indicate that Guanabara Bay plays a central role in supporting large populations of fishes, including commercially important species. PMID:27401484

  3. Overexpression of an AP2/ERF Type Transcription Factor OsEREBP1 Confers Biotic and Abiotic Stress Tolerance in Rice

    PubMed Central

    Jisha, V.; Ramanan, Rajeshwari

    2015-01-01

    AP2/ERF–type transcription factors regulate important functions of plant growth and development as well as responses to environmental stimuli. A rice AP2/ERF transcription factor, OsEREBP1 is a downstream component of a signal transduction pathway in a specific interaction between rice (Oryza sativa) and its bacterial pathogen, Xoo (Xanthomonas oryzae pv. oryzae). Constitutive expression of OsEREBP1 in rice driven by maize ubiquitin promoter did not affect normal plant growth. Microarray analysis revealed that over expression of OsEREBP1 caused increased expression of lipid metabolism related genes such as lipase and chloroplastic lipoxygenase as well as several genes related to jasmonate and abscisic acid biosynthesis. PR genes, transcription regulators and Aldhs (alcohol dehydrogenases) implicated in abiotic stress and submergence tolerance were also upregulated in transgenic plants. Transgenic plants showed increase in endogenous levels of α-linolenate, several jasmonate derivatives and abscisic acid but not salicylic acid. Soluble modified GFP (SmGFP)-tagged OsEREBP1 was localized to plastid nucleoids. Comparative analysis of non-transgenic and OsEREBP1 overexpressing genotypes revealed that OsEREBP1 attenuates disease caused by Xoo and confers drought and submergence tolerance in transgenic rice. Our results suggest that constitutive expression of OsEREBP1 activates the jasmonate and abscisic acid signalling pathways thereby priming the rice plants for enhanced survival under abiotic or biotic stress conditions. OsEREBP1 is thus, a good candidate gene for engineering plants for multiple stress tolerance. PMID:26035591

  4. The CarERF genes in chickpea (Cicer arietinum L.) and the identification of CarERF116 as abiotic stress responsive transcription factor.

    PubMed

    Deokar, Amit A; Kondawar, Vishwajith; Kohli, Deshika; Aslam, Mohammad; Jain, Pradeep K; Karuppayil, S Mohan; Varshney, Rajeev K; Srinivasan, Ramamurthy

    2015-01-01

    The AP2/ERF family is one of the largest transcription factor gene families that are involved in various plant processes, especially in response to biotic and abiotic stresses. Complete genome sequences of one of the world's most important pulse crops chickpea (Cicer arietinum L.), has provided an important opportunity to identify and characterize genome-wide ERF genes. In this study, we identified 120 putative ERF genes from chickpea. The genomic organization of the chickpea ERF genes suggested that the gene family might have been expanded through the segmental duplications. The 120 member ERF family was classified into eleven distinct groups (I-X and VI-L). Transcriptional factor CarERF116, which is differentially expressed between drought tolerant and susceptible chickpea cultivar under terminal drought stress has been identified and functionally characterized. The CarERF116 encodes a putative protein of 241 amino acids and classified into group IX of ERF family. An in vitro CarERF116 protein-DNA binding assay demonstrated that CarERF116 protein specifically interacts with GCC box. We demonstrate that CarERF116 is capable of transactivation activity of and show that the functional transcriptional domain lies at the C-terminal region of the CarERF116. In transgenic Arabidopsis plants overexpressing CarERF116, significant up-regulation of several stress related genes were observed. These plants also exhibit resistance to osmotic stress and reduced sensitivity to ABA during seed germination. Based on these findings, we conclude that CarERF116 is an abiotic stress responsive gene, which plays an important role in stress tolerance. In addition, the present study leads to genome-wide identification and evolutionary analyses of chickpea ERF gene family, which will facilitate further research on this important group of genes and provides valuable resources for comparative genomics among the grain legumes. PMID:25274312

  5. The auxin response factor gene family in banana: genome-wide identification and expression analyses during development, ripening, and abiotic stress

    PubMed Central

    Hu, Wei; Zuo, Jiao; Hou, Xiaowan; Yan, Yan; Wei, Yunxie; Liu, Juhua; Li, Meiying; Xu, Biyu; Jin, Zhiqiang

    2015-01-01

    Auxin signaling regulates various auxin-responsive genes via two types of transcriptional regulators, Auxin Response Factors (ARF) and Aux/IAA. ARF transcription factors act as critical components of auxin signaling that play important roles in modulating various biological processes. However, limited information about this gene family in fruit crops is currently available. Herein, 47 ARF genes were identified in banana based on its genome sequence. Phylogenetic analysis of the ARFs from banana, rice, and Arabidopsis suggested that the ARFs could be divided into four subgroups, among which most ARFs from the banana showed a closer relationship with those from rice than those from Arabidopsis. Conserved motif analysis showed that all identified MaARFs had typical DNA-binding and ARF domains, but 12 members lacked the dimerization domain. Gene structure analysis showed that the number of exons in MaARF genes ranged from 5 to 21, suggesting large variation amongst banana ARF genes. The comprehensive expression profiles of MaARF genes yielded useful information about their involvement in diverse tissues, different stages of fruit development and ripening, and responses to abiotic stresses in different varieties. Interaction networks and co-expression assays indicated the strong transcriptional response of banana ARFs and ARF-mediated networks in early fruit development for different varieties. Our systematic analysis of MaARFs revealed robust tissue-specific, development-dependent, and abiotic stress-responsive candidate MaARF genes for further functional assays in planta. These findings could lead to potential applications in the genetic improvement of banana cultivars, and yield new insights into the complexity of the control of MaARF gene expression at the transcriptional level. Finally, they support the hypothesis that ARFs are a crucial component of the auxin signaling pathway, which regulates a wide range of physiological processes. PMID:26442055

  6. The auxin response factor gene family in banana: genome-wide identification and expression analyses during development, ripening, and abiotic stress.

    PubMed

    Hu, Wei; Zuo, Jiao; Hou, Xiaowan; Yan, Yan; Wei, Yunxie; Liu, Juhua; Li, Meiying; Xu, Biyu; Jin, Zhiqiang

    2015-01-01

    Auxin signaling regulates various auxin-responsive genes via two types of transcriptional regulators, Auxin Response Factors (ARF) and Aux/IAA. ARF transcription factors act as critical components of auxin signaling that play important roles in modulating various biological processes. However, limited information about this gene family in fruit crops is currently available. Herein, 47 ARF genes were identified in banana based on its genome sequence. Phylogenetic analysis of the ARFs from banana, rice, and Arabidopsis suggested that the ARFs could be divided into four subgroups, among which most ARFs from the banana showed a closer relationship with those from rice than those from Arabidopsis. Conserved motif analysis showed that all identified MaARFs had typical DNA-binding and ARF domains, but 12 members lacked the dimerization domain. Gene structure analysis showed that the number of exons in MaARF genes ranged from 5 to 21, suggesting large variation amongst banana ARF genes. The comprehensive expression profiles of MaARF genes yielded useful information about their involvement in diverse tissues, different stages of fruit development and ripening, and responses to abiotic stresses in different varieties. Interaction networks and co-expression assays indicated the strong transcriptional response of banana ARFs and ARF-mediated networks in early fruit development for different varieties. Our systematic analysis of MaARFs revealed robust tissue-specific, development-dependent, and abiotic stress-responsive candidate MaARF genes for further functional assays in planta. These findings could lead to potential applications in the genetic improvement of banana cultivars, and yield new insights into the complexity of the control of MaARF gene expression at the transcriptional level. Finally, they support the hypothesis that ARFs are a crucial component of the auxin signaling pathway, which regulates a wide range of physiological processes. PMID:26442055

  7. Abiotic formation of volatile organic compounds from plant biomass and its dependence on temperature and UV radiation

    NASA Astrophysics Data System (ADS)

    Derendorp, L.; Holzinger, R.; Röckmann, T.

    2009-04-01

    The emissions of volatile organic compounds (VOCs) from living vegetation are measured for many different plant species. However, almost no research has been performed on the VOC emissions from plant litter and senescent leaves. The few studies that are done on plant litter indicate that the VOC emissions from this material can be significant for atmospheric chemistry and the global budgets of those VOCs. Recently, research showed that methane is emitted from dead and senescent leaves, and that the emission rates are influenced by temperature and ultraviolet (UV) radiation. It is also observed that not only methane, but also ethane and ethylene were emitted from leaf material under the influence of UV radiation. In this study, the emissions of ethane, ethylene, acetylene, propane, propylene, i-butane, n-butane and methyl chloride are measured with a gas chromatograph with a flame ionization detector. The effect of temperature and UV radiation on the emission rates of the different VOCs is measured for leaves of several plant species. The emission rates of ethane, ethylene, propane, propylene, and methylchloride increased exponentially with increasing temperature for all measured plant species, while a linear increase of the emission rates was observed for increasing intensity of the UV radiation. Emissions of acetylene, i-butane, and n-butane were not observed.

  8. Simultaneous Expression of Abiotic Stress Responsive Transcription Factors, AtDREB2A, AtHB7 and AtABF3 Improves Salinity and Drought Tolerance in Peanut (Arachis hypogaea L.)

    PubMed Central

    Pruthvi, Vittal; Narasimhan, Rama; Nataraja, Karaba N.

    2014-01-01

    Drought, salinity and extreme temperatures are the most common abiotic stresses, adversely affecting plant growth and productivity. Exposure of plants to stress activates stress signalling pathways that induce biochemical and physiological changes essential for stress acclimation. Stress tolerance is governed by multiple traits, and importance of a few traits in imparting tolerance has been demonstrated. Under drought, traits linked to water mining and water conservation, water use efficiency and cellular tolerance (CT) to desiccation are considered to be relevant. In this study, an attempt has been made to improve CT in drought hardy crop, peanut (Arachis hypogaea L., cv. TMV2) by co-expressing stress-responsive transcription factors (TFs), AtDREB2A, AtHB7 and AtABF3, associated with downstream gene expression. Transgenic plants simultaneously expressing these TFs showed increased tolerance to drought, salinity and oxidative stresses compared to wild type, with an increase in total plant biomass. The transgenic plants exhibited improved membrane and chlorophyll stability due to enhanced reactive oxygen species scavenging and osmotic adjustment by proline synthesis under stress. The improvement in stress tolerance in transgenic lines were associated with induced expression of various CT related genes like AhGlutaredoxin, AhAldehyde reductase, AhSerine threonine kinase like protein, AhRbx1, AhProline amino peptidase, AhHSP70, AhDIP and AhLea4. Taken together the results indicate that co-expression of stress responsive TFs can activate multiple CT pathways, and this strategy can be employed to improve abiotic stress tolerance in crop plants. PMID:25474740

  9. Simultaneous expression of abiotic stress responsive transcription factors, AtDREB2A, AtHB7 and AtABF3 improves salinity and drought tolerance in peanut (Arachis hypogaea L.).

    PubMed

    Pruthvi, Vittal; Narasimhan, Rama; Nataraja, Karaba N

    2014-01-01

    Drought, salinity and extreme temperatures are the most common abiotic stresses, adversely affecting plant growth and productivity. Exposure of plants to stress activates stress signalling pathways that induce biochemical and physiological changes essential for stress acclimation. Stress tolerance is governed by multiple traits, and importance of a few traits in imparting tolerance has been demonstrated. Under drought, traits linked to water mining and water conservation, water use efficiency and cellular tolerance (CT) to desiccation are considered to be relevant. In this study, an attempt has been made to improve CT in drought hardy crop, peanut (Arachis hypogaea L., cv. TMV2) by co-expressing stress-responsive transcription factors (TFs), AtDREB2A, AtHB7 and AtABF3, associated with downstream gene expression. Transgenic plants simultaneously expressing these TFs showed increased tolerance to drought, salinity and oxidative stresses compared to wild type, with an increase in total plant biomass. The transgenic plants exhibited improved membrane and chlorophyll stability due to enhanced reactive oxygen species scavenging and osmotic adjustment by proline synthesis under stress. The improvement in stress tolerance in transgenic lines were associated with induced expression of various CT related genes like AhGlutaredoxin, AhAldehyde reductase, AhSerine threonine kinase like protein, AhRbx1, AhProline amino peptidase, AhHSP70, AhDIP and AhLea4. Taken together the results indicate that co-expression of stress responsive TFs can activate multiple CT pathways, and this strategy can be employed to improve abiotic stress tolerance in crop plants. PMID:25474740

  10. Genome-wide analysis of AP2/ERF transcription factors in carrot (Daucus carota L.) reveals evolution and expression profiles under abiotic stress.

    PubMed

    Li, Meng-Yao; Xu, Zhi-Sheng; Huang, Ying; Tian, Chang; Wang, Feng; Xiong, Ai-Sheng

    2015-12-01

    AP2/ERF is a large transcription factor family that regulates plant physiological processes, such as plant development and stress response. Carrot (Daucus carota L.) is an important economical crop with a genome size of 480 Mb; the draft genome sequencing of this crop has been completed by our group. However, little is known about the AP2/ERF factors in carrot. In this study, a total of 267 putative AP2/ERF factors were identified from the whole-genome sequence of carrot. These AP2/ERF proteins were phylogenetically clustered into five subfamilies based on their similarity to the amino acid sequences from Arabidopsis. The distribution and comparative genome analysis of the AP2/ERF factors among plants showed the AP2/ERF factors had expansion during the evolutionary process, and the AP2 domain was highly conserved during evolution. The number of AP2/ERF factors in land plants expanded during their evolution. A total of 60 orthologous and 145 coorthologous AP2/ERF gene pairs between carrot and Arabidopsis were identified, and the interaction network of orthologous genes was constructed. The expression patterns of eight AP2/ERF family genes from each subfamily (DREB, ERF, AP2, and RAV) were related to abiotic stresses. Yeast one-hybrid and β-galactosidase activity assays confirmed the DRE and GCC box-binding activities of DREB subfamily genes. This study is the first to identify and characterize the AP2/ERF transcription factors in carrot using whole-genome analysis, and the findings may serve as references for future functional research on the transcription factors in carrot. PMID:25971861

  11. Effect of elevated CO2 and temperature on abiotic and biologically-driven basalt weathering and C sequestration

    NASA Astrophysics Data System (ADS)

    Dontsova, K.; Juarez, S.; Le Galliard, J. F.; Chollet, S.; Cros, A.; Llavata, M.; Massol, F.; Barré, P.; Gelabert, A.; Daval, D.; Corvisier, J.; Troch, P. A. A.; Barron-Gafford, G.; Van Haren, J. L. M.; Ferrière, R.

    2015-12-01

    Weathering of primary silicates is one of the mechanisms involved in carbon removal from the atmosphere, affecting the carbon cycle at geologic timescales with basalt significantly contributing to the global weathering CO2 flux. Mineral weathering can be enhanced by microbiota and plants. Increase in both temperature and amount of CO2 in the atmosphere can directly increase weathering and can also affect weathering through impact on biological systems. This would result in possible negative feedback on climate change. The goal of this research was to quantify direct and indirect effects of temperature and elevated CO2 on basalt weathering and carbon sequestration. In order to achieve this goal we performed controlled-environment mesocosm experiments at Ecotron Ile-de-France. Granular basalt collected in Flagstaff, AZ was exposed to rainfall at equilibrium with two different CO2 concentrations in the air, ambient (400 ppm) and elevated (800 ppm); and kept at two climate regimes, with ambient and elevated (+ 4° C) temperature. Four biological treatments were superimposed on this design: a plant-free control; N-fixing grass (alfalfa, Medicago sativa), N-fixing tree (Velvet mesquite, Prosopis velutina); and grass that does not form symbiotic relationships with N fixers (Green Sprangletop, Leptochloa dubia). All used basalt had native microbial community. Mesocosms were equipped with solution and gas samplers. To monitor biogenic and lithogenic weathering product concentrations, soil solution samples were collected under vacuum after each rainfall event and analyzed to determine pH, electrical conductivity, major and trace elements concentrations, anions concentrations, and aqueous phase organic matter chemistry. Soil gases were monitored for CO2 using porous Teflon gas samplers connected to the Vaisala probes. Plant biomass was collected at the end of the experiment to determine dry weight, as well as removal of N and lithogenic elements by the plants. Solid samples

  12. Effect of elevated CO2 and temperature on abiotic and biologically-driven basalt weathering and C sequestration

    NASA Astrophysics Data System (ADS)

    Juarez, Sabrina; Dontsova, Katerina; Le Galliard, Jean-François; Chollet, Simon; Llavata, Mathieu; Massol, Florent; Cros, Alexis; Barré, Pierre; Gelabert, Alexandre; Daval, Damien; Corvisier, Jérôme; Troch, Peter; Barron-Gafford, Greg; Van Haren, Joost; Ferrière, Régis

    2016-04-01

    Weathering of primary silicates is one of the mechanisms involved in carbon removal from the atmosphere, affecting the carbon cycle at geologic timescales with basalt significantly contributing to the global weathering CO2 flux. Mineral weathering can be enhanced by microbiota and plants. Increase in both temperature and amount of CO2 in the atmosphere can directly increase weathering and can also affect weathering through impact on biological systems. This would result in possible negative feedback on climate change. The goal of this research was to quantify direct and indirect effects of temperature and elevated CO2 on basalt weathering and carbon sequestration. In order to achieve this goal we performed controlled-environment mesocosm experiments at Ecotron Ile-de-France (France). Granular basalt collected in Flagstaff (AZ, USA) was exposed to rainfall at equilibrium with two different CO2 concentrations in the air, ambient (400 ppm) and elevated (800 ppm); and kept at two climate regimes, with ambient and elevated (+ 4° C) temperature. Four biological treatments were superimposed on this design: a plant-free control; N-fixing grass (Alfalfa, Medicago sativa), N-fixing tree (Velvet mesquite, Prosopis velutina); and grass that does not form symbiotic relationships with N fixers (Green Sprangletop, Leptochloa dubia). All used basalt had native microbial community. Mesocosms were equipped with solution and gas samplers. To monitor biogenic and lithogenic weathering product concentrations, soil solution samples were collected under vacuum after each rainfall event and analyzed to determine pH, electrical conductivity, major and trace elements concentrations, anions concentrations, and aqueous phase organic matter chemistry. Soil gases were monitored for CO2 using porous Teflon gas samplers connected to the Vaisala probes. Plant biomass was collected at the end of the experiment to determine dry weight, as well as removal of N and lithogenic elements by the plants

  13. Recent advances in polyamine metabolism and abiotic stress tolerance.

    PubMed

    Rangan, Parimalan; Subramani, Rajkumar; Kumar, Rajesh; Singh, Amit Kumar; Singh, Rakesh

    2014-01-01

    Global warming is an alarming problem in agriculture and its effect on yield loss has been estimated to be five per cent for every degree centigrade rise in temperature. Plants exhibit multiple mechanisms like optimizing signaling pathway, involvement of secondary messengers, production of biomolecules specifically in response to stress, modulation of various metabolic networks in accordance with stress, and so forth, in order to overcome abiotic stress factors. Many structural genes and networks of pathway were identified and reported in plant systems for abiotic stress tolerance. One such crucial metabolic pathway that is involved in normal physiological function and also gets modulated during stress to impart tolerance is polyamine metabolic pathway. Besides the role of structural genes, it is also important to know the mechanism by which these structural genes are regulated during stress. Present review highlights polyamine biosynthesis, catabolism, and its role in abiotic stress tolerance with special reference to plant systems. Additionally, a system based approach is discussed as a potential strategy to dissect the existing variation in crop species in unraveling the interacting regulatory components/genetic determinants related to PAs mediated abiotic stress tolerance. PMID:25136565

  14. Plastid transformation for abiotic stress tolerance in plants.

    PubMed

    Bansal, K C; Singh, A K; Wani, S H

    2012-01-01

    Abiotic stresses such as drought, salinity, and extreme temperatures are major limiting factors in plant growth and development and pose serious threat to global agricultural production. Here we describe a procedure, using a tobacco plastid transformation vector, to generate transplastomic plants with an enhanced ability to tolerate abiotic stresses such as salinity, drought, or cold stress. The procedure involves biolistic delivery of a plastid transformation vector into explants, antibiotic selection procedures, and -identification of transplastomic lines. The plastid transformation vector contains an aadA gene that encodes resistance to spectinomycin as a selectable marker along with the gene of interest for developing transplastomic plants that are tolerant to abiotic stresses. Shoot buds appear over the surface of bombarded explants following spectinomycin selection. Transplastomic shoots are multiplied following several rounds of -spectinomycin selection. Homoplasmic transplastomic lines are confirmed by spectinomycin and streptomycin double selection over a period of 4-5 weeks. The available reports suggest that transplastomic technology is a useful tool for expressing genes in plastids or chloroplasts for enhancing abiotic stress tolerance in plants. PMID:22895771

  15. Recent Advances in Polyamine Metabolism and Abiotic Stress Tolerance

    PubMed Central

    Rangan, Parimalan; Subramani, Rajkumar; Singh, Amit Kumar

    2014-01-01

    Global warming is an alarming problem in agriculture and its effect on yield loss has been estimated to be five per cent for every degree centigrade rise in temperature. Plants exhibit multiple mechanisms like optimizing signaling pathway, involvement of secondary messengers, production of biomolecules specifically in response to stress, modulation of various metabolic networks in accordance with stress, and so forth, in order to overcome abiotic stress factors. Many structural genes and networks of pathway were identified and reported in plant systems for abiotic stress tolerance. One such crucial metabolic pathway that is involved in normal physiological function and also gets modulated during stress to impart tolerance is polyamine metabolic pathway. Besides the role of structural genes, it is also important to know the mechanism by which these structural genes are regulated during stress. Present review highlights polyamine biosynthesis, catabolism, and its role in abiotic stress tolerance with special reference to plant systems. Additionally, a system based approach is discussed as a potential strategy to dissect the existing variation in crop species in unraveling the interacting regulatory components/genetic determinants related to PAs mediated abiotic stress tolerance. PMID:25136565

  16. Biotic and abiotic drivers of phenotypic plasticity of wing dimorphism in Sclerodermus pupariae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wing phenotype polymorphism is commonly observed in insects, yet little is known about the influence of environmental cues on the development or expression of the alternative phenotypes. Here, we examined the effects of biotic and abiotic factors including temperature, photoperiod, light intensity,...

  17. Temperature controls on sediment production in the Oregon Coast Range - abiotic frost-cracking processes vs. biotic-dominated processes over the last 40 ka

    NASA Astrophysics Data System (ADS)

    Marshall, J. A.; Roering, J. J.; Praskievicz, S. J.; Hales, T. C.; Gavin, D. G.; Bartlein, P. J.

    2012-12-01

    The Oregon Coast Range (OCR) is a mid-latitude soil-mantled landscape wherein measured uplift rates are broadly consistent with long-term measured erosion rates. The OCR was unglaciated during the last glacial period (~ 26 to 13 ka) and therefore is considered an ideal steady-state landscape to study and model geomorphic processes. However, previously published paleoclimate data inferred from a 42 ka paleolake fossil archive in the OCR Little Lake watershed (3 km2) strongly suggest that temperatures in the OCR during the last glacial were well within the frost cracking temperature window of -3 to -8 °C. Therefore, we suggest that while present-day OCR sediment production is dominated by biota, specifically trees, frost-driven abiotic processes may have played a significant role in modulating erosion rates and landscape evolution during the last glacial interval. A new sediment core from the Little Lake basin at the lake's edge, centered proximal to hillslopes, spans ~ 50 ka to 20 ka. We observe a fourfold increase in sediment accumulation rates from the non-glacial interval (~50 ka to ~ 26 ka) to the last glacial interval (~ 26 ka to ~ 20 ka), including > 12 m of sediment from the last glacial maximum, dated at 23,062 - 23,581 cal yr B.P. The decreased inferred temperatures and increased sedimentation rates suggest increased sediment production and transport via frost processes during the last glacial interval, in contrast to sediment production and erosion rates controlled by biotic processes in the non-glacial intervals. We present a climate-time series scenario of likely frost-cracking intensity across the entire Oregon Coast Range from the non-glacial interval (at least 3 °C cooler than present-day temperatures) through the glacial interval (7 to 14 °C cooler) and into the Holocene (January temperatures ~ 5 °C). We use the PRISM dataset, which consists of monthly temperature and precipitation for the contiguous United States, to calculate local monthly

  18. EsDREB2B, a novel truncated DREB2-type transcription factor in the desert legume Eremosparton songoricum, enhances tolerance to multiple abiotic stresses in yeast and transgenic tobacco

    PubMed Central

    2014-01-01

    Background Dehydration-Responsive Element-Binding Protein2 (DREB2) is a transcriptional factor which regulates the expression of several stress-inducible genes. DREB2-type proteins are particularly important in plant responses to drought, salt and heat. DREB2 genes have been identified and characterized in a variety of plants, and DREB2 genes are promising candidate genes for the improvement of stress tolerance in plants. However, little is known about these genes in plants adapted to water-limiting environments. Results In this study, we describe the characterization of EsDREB2B, a novel DREB2B gene identified from the desert plant Eremosparton songoricum. Phylogenetic analysis and motif prediction indicate that EsDREB2B encodes a truncated DREB2 polypeptide that belongs to a legume-specific DREB2 group. In E. songoricum, EsDREB2B transcript accumulation was induced by a variety of abiotic stresses, including drought, salinity, cold, heat, heavy metal, mechanical wounding, oxidative stress and exogenous abscisic acid (ABA) treatment. Consistent with the predicted role as a transcription factor, EsDREB2B was targeted to the nucleus of onion epidermal cells and exhibited transactivation activity of a GAL4-containing reporter gene in yeast. In transgenic yeast, overexpression of EsDREB2B increased tolerance to multiple abiotic stresses. Our findings indicate that EsDREB2B can enhance stress tolerance in other plant species. Heterologous expression of EsDREB2B in tobacco showed improved tolerance to multiple abiotic stresses, and the transgenic plants exhibited no reduction in foliar growth. We observed that EsDREB2B is a functional DREB2-orthologue able to influence the physiological and biochemical response of transgenic tobacco to stress. Conclusions Based upon these findings, EsDREB2B encodes an abiotic stress-inducible, transcription factor which confers abiotic stress-tolerance in yeast and transgenic tobacco. PMID:24506952

  19. Temperature Dependence of Factors Controlling Isoprene Emissions

    NASA Technical Reports Server (NTRS)

    Duncan, Bryan N.; Yoshida, Yasuko; Damon, Megan R.; Douglass, Anne R.; Witte, Jacquelyn C.

    2009-01-01

    We investigated the relationship of variability in the formaldehyde (HCHO) columns measured by the Aura Ozone Monitoring Instrument (OMI) to isoprene emissions in the southeastern United States for 2005-2007. The data show that the inferred, regional-average isoprene emissions varied by about 22% during summer and are well correlated with temperature, which is known to influence emissions. Part of the correlation with temperature is likely associated with other causal factors that are temperature-dependent. We show that the variations in HCHO are convolved with the temperature dependence of surface ozone, which influences isoprene emissions, and the dependence of the HCHO column to mixed layer height as OMI's sensitivity to HCHO increases with altitude. Furthermore, we show that while there is an association of drought with the variation in HCHO, drought in the southeastern U.S. is convolved with temperature.

  20. [Role of the NO Synthase System in Response to Abiotic Stress Factors for Basidiomycetes Lentinula edodes and Grifola frondosa].

    PubMed

    Loshchinina, E A; Nikitina, V E

    2016-01-01

    Effect of stressors (unfavorable pH and temperature or carbon and nitrogen limitation) on the synthesis of the components of the NO synthase signaling system was studied in submerged cultures of xylotrophic basidiomycetes Lentinula edodes and Grifola frondosa. Marker compounds of the NO synthase signaling system were found in both cultures. A simultaneous increase of the concentrations of NO and citrulline in the culture liquid of the basidiomycetes grown at superoptimal pH and in nitrogen-limited medium indicates the activation of the NO synthase signaling system under such stress conditions. PMID:27476203

  1. ZmGOLS2, a target of transcription factor ZmDREB2A, offers similar protection against abiotic stress as ZmDREB2A.

    PubMed

    Gu, Lei; Zhang, Yumin; Zhang, Mingshuai; Li, Tao; Dirk, Lynnette M A; Downie, Bruce; Zhao, Tianyong

    2016-01-01

    GALACTINOL SYNTHASE is the first committed enzyme in the raffinose biosynthetic pathway. We have previously characterized the maize (Zea mays) GALACTINOL SYNTHASE2 gene (ZmGOLS2) as abiotic stress induced. To further investigate the regulation of ZmGOLS2 gene expression, individual luciferase expression vectors,in which the luciferase gene was controlled by different lengths of the ZmGOLS2 promoter, were co-transfected into maize protoplasts with either a ZmDREB2A- or a GFP-expression vector. Over-expression of ZmDREB2A up-regulated both the expression of the luciferase gene controlled by the ZmGOLS2 promoter and the endogenous ZmGOLS2 gene in protoplasts. Only one of the two DRE elements in the ZmGOLS2 promoter was identified as necessary for this up-regulation. Expression vectors of GFP, ZmGOLS2 or ZmDREB2A were stably transformed into Arabidopsis. Expression of ZmDREB2A up-regulated the AtGOLS3 gene but only over-expression of ZmGOLS2 resulted in hyper-accumulation of galactinol and raffinose. Regardless, under drought-, heat shock-, high osmotic- or salinity-stress conditions, both the ZmGOLS2- and the ZmDREB2A- expressing plants had greater germination percentages, greater percentages of seedlings becoming autotropic, and/or greater survival percentages during/after stress than the control plants. Under normal growing conditions, transgenic Arabidopsis plants expressing the ZmGOLS2 gene had similar growth to that of untransformed wild type or GFP-expressing control plants, whereas ZmDREB2A over-expressing plants exhibited retarded growth relative to either of the controls. These data suggest that over-expression of ZmGOLS2, rather than the transcription factor ZmDREB2A, is a more practical target for generation of abiotic-stress tolerant crops. PMID:26584560

  2. Interactions among biotic and abiotic factors affect the reliability of tungsten microneedles puncturing in vitro and in vivo peripheral nerves: A hybrid computational approach.

    PubMed

    Sergi, Pier Nicola; Jensen, Winnie; Yoshida, Ken

    2016-02-01

    Tungsten is an elective material to produce slender and stiff microneedles able to enter soft tissues and minimize puncture wounds. In particular, tungsten microneedles are used to puncture peripheral nerves and insert neural interfaces, bridging the gap between the nervous system and robotic devices (e.g., hand prostheses). Unfortunately, microneedles fail during the puncture process and this failure is not dependent on stiffness or fracture toughness of the constituent material. In addition, the microneedles' performances decrease during in vivo trials with respect to the in vitro ones. This further effect is independent on internal biotic effects, while it seems to be related to external biotic causes. Since the exact synergy of phenomena decreasing the in vivo reliability is still not known, this work explored the connection between in vitro and in vivo behavior of tungsten microneedles through the study of interactions between biotic and abiotic factors. A hybrid computational approach, simultaneously using theoretical relationships and in silico models of nerves, was implemented to model the change of reliability varying the microneedle diameter, and to predict in vivo performances by using in vitro reliability and local differences between in vivo and in vitro mechanical response of nerves. PMID:26652468

  3. Aquatic macroinvertebrates associated with Eichhornia azurea (Swartz) Kunth and relationships with abiotic factors in marginal lentic ecosystems (São Paulo, Brazil).

    PubMed

    Silva, C V; Henry, R

    2013-02-01

    Marginal lakes are characterised by their having high biological diversity due to the presence of aquatic macrophytes in their coastal zones, providing habitats for refuge and food for animal community members. Among the fauna components associated with macrophytes, aquatic macroinvertebrates are important because they are an energy source for predators and fish. In six lakes and two different seasons (March and August 2009), the ecological attributes of aquatic macroinvertebrate community associated with Eichhornia azurea were compared and the controlling environmental factors were identified. Since the attributes of macroinvertebrate community are strictly associated with abiotic variables of each distinct habitat, our hypothesis was that each site associated with the same floating aquatic macrophyte (E. azurea) should have a typical composition and density of organisms. We identified 50 taxa of macroinvertebrates, with greater taxa richness for aquatic insects (37 taxa) divided into eight orders; the order Diptera being the most abundant in the two study periods. On the other hand, higher values of total taxa richness were recorded in August. Dissolved oxygen and pH presented the greatest number of significant positive correlations with the different taxa. The animals most frequently collected in the six lakes in March and August 2009 were Hirudinea, Oligochaeta, Hydrachnidae, Conchostraca, Ostracoda, Noteridae, Ceratopogonidae, Chironomidae, Culicidae, Caenidae, Pleidae, Aeshnidae, Libellulidae, Coenagrionidae and Nematoda. Only densities of Trichoptera, Ostracoda and Conchostraca presented the highest significant differences between lakes in both study periods and considering the composition of macroinvertebrates no significant differences were registered for macroinvertebrate composition. PMID:23644797

  4. The heat shock factor gene family in Salix suchowensis: a genome-wide survey and expression profiling during development and abiotic stresses

    PubMed Central

    Zhang, Jin; Li, Yu; Jia, Hui-Xia; Li, Jian-Bo; Huang, Juan; Lu, Meng-Zhu; Hu, Jian-Jun

    2015-01-01

    Heat shock transcription factors (Hsfs), which act as important transcriptional regulatory proteins, play crucial roles in plant developmental processes, and stress responses. Recently, the genome of the shrub willow Salix suchowensis was fully sequenced. In this study, a total of 27 non-redundant Hsf genes were identified from the S. suchowensis genome. Phylogenetic analysis revealed that the members of the SsuHsf family can be divided into three groups (class A, B, and C) based on their structural characteristics. Promoter analysis indicated that the SsuHsfs promoters included various cis-acting elements related to hormone and/or stress responses. Furthermore, the expression profiles of 27 SsuHsfs were analyzed in different tissues and under various stresses (heat, drought, salt, and ABA treatment) using RT-PCR. The results demonstrated that the SsuHsfs were involved in abiotic stress responses. Our results contribute to a better understanding of the complexity of the SsuHsf gene family, and will facilitate functional characterization in future studies. PMID:26442061

  5. The cowpea RING ubiquitin ligase VuDRIP interacts with transcription factor VuDREB2A for regulating abiotic stress responses.

    PubMed

    Sadhukhan, Ayan; Panda, Sanjib Kumar; Sahoo, Lingaraj

    2014-10-01

    Cowpea (Vigna unguiculata L. Walp) is an important grain legume cultivated in drought-prone parts of the world, having higher tolerance to heat and drought than many other crops. The transcription factor, Dehydration-Responsive Element-Binding protein 2A (DREB2A), controls expression of many genes involved in osmotic and heat stress responses of plants. In Arabidopsis, DREB2A-interacting proteins (DRIPs), which function as E3 ubiquitin ligases (EC 6.3.2.19), regulate the stability of DREB2A by targeting it for proteasome-mediated degradation. In this study, we cloned the cowpea ortholog of DRIP (VuDRIP) using PCR based methods. The 1614 bp long VuDRIP mRNA encoded a protein of 433 amino acids having a C3HC4-type Really Interesting New Gene (RING) domain in the N-terminus and a C-terminal conserved region, similar to Arabidopsis DRIP1 and DRIP2. We found VuDRIP up-regulation in response to various abiotic stresses and phytohormones. Using yeast (Saccharomyces cerevisae) two-hybrid analysis, VuDRIP was identified as a VuDREB2A-interacting protein. The results indicate negative regulation of VuDREB2A by ubiquitin ligases in cowpea similar to Arabidopsis along with their other unknown roles in stress and hormone signaling pathways. PMID:25090086

  6. Biotic and abiotic factors related to rainbow smelt recruitment in the Wisconsin waters of Lake Superior, 1978-1997

    USGS Publications Warehouse

    Hoff, Michael H.

    2004-01-01

    Lake Superior rainbow smelt (Osmerus mordax) recruitment to 12-13 months of age in the Wisconsin waters of Lake Superior varied by a factor of 9.3 during 1978-1997. Management agencies have sought models that accurately predict recruitment, but no satisfactory models had previously been developed. In this study, modeling was conducted to determine which factors best explained recruitment variability. The Ricker stock-recruitment model derived from only the paired stock and recruit data accounted for 63% of the variability in recruitment data. The functional relationship that accounted for the greatest amount of recruitment variation (81%) included rainbow smelt stock size, May rainfall, and bloater (Coregonus hoyi) biomass. Model results were interpreted to mean that recruitment was affected negatively by increased river flows from increased rainfall, and affected positively by the biomass of bloater, and those results were interpreted to mean that bloater mediated the effects of lake trout predation on rainbow smelt recruits. Model results were also interpreted to mean that stock size caused compensatory, density-dependent mortality on rainbow smelt recruits. Correlations observed here may be of value to managers seeking approaches to either enhance or control populations of this species, which is not indigenous to the Great Lakes.

  7. Abiotic and biotic stress tolerance in Arabidopsis overexpressing the multiprotein bridging factor 1a (MBF1a) transcriptional coactivator gene.

    PubMed

    Kim, Min-Jung; Lim, Gah-Hyun; Kim, Eun-Seon; Ko, Chang-Beom; Yang, Kwang-Yeol; Jeong, Jin-An; Lee, Myung-Chul; Kim, Cheol Soo

    2007-03-01

    We conducted a genetic yeast screen to identify salt tolerance (SAT) genes in a maize kernel cDNA library. During the screening, we identified a maize clone (SAT41) that seemed to confer elevated salt tolerance in comparison to control cells. SAT41 cDNA encodes a 16-kDa protein which is 82.4% identical to the Arabidopsis Multiprotein bridging factor 1a (MBF1a) transcriptional coactivator gene. To further examine salinity tolerance in Arabidopsis, we functionally characterized the MBF1a gene and found that dehydration as well as heightened glucose (Glc) induced MBF1a expression. Constitutive expression of MBF1a in Arabidopsis led to elevated salt tolerance in transgenic lines. Interestingly, plants overexpressing MBF1a exhibited insensitivity to Glc and resistance to fungal disease. Our results suggest that MBF1a is involved in stress tolerance as well as in ethylene and Glc signaling in Arabidopsis. PMID:17234157

  8. The influence of biotic and abiotic factors on (137)Cs accumulation in higher fungi after the accident at Chernobyl NPP.

    PubMed

    Zarubina, N

    2016-09-01

    Levels of soil contamination with (137)Cs, the belonging of fungi to a certain ecological group, the localization depth of the main part of mycelium in soil are the primary factors influencing the value of (137)Cs specific activity in higher fungi after the accident at Chernobyl NPP. It has been found that the value of (137)Cs specific activity in fungi of one species could vary by more than 10 times during a vegetation period. A correlation between the changes of (137)Cs content in fungi during the vegetation period and the amount of precipitates during various periods preceding the collection of samples has not been determined. An assumption has been proposed stating dependence between peculiarities of mycelium growth during the vegetation period and the changes of (137)Cs specific activity in fungi. PMID:26690320

  9. Molecular cloning and expression profile of an abiotic stress and hormone responsive MYB transcription factor gene from Panax ginseng.

    PubMed

    Afrin, Sadia; Zhu, Jie; Cao, Hongzhe; Huang, Jingjia; Xiu, Hao; Luo, Tiao; Luo, Zhiyong

    2015-04-01

    The v-myb avian myeloblastosis viral oncogene homolog (MYB) family constitutes one of the most abundant groups of transcription factors and plays vital roles in developmental processes and defense responses in plants. A ginseng (Panax ginseng C.A. Meyer) MYB gene was cloned and designated as PgMYB1. The cDNA of PgMYB1 is 762 base pairs long and encodes the R2R3-type protein consisting 238 amino acids. Subcellular localization showed that PgMYB1-mGFP5 fusion protein was specifically localized in the nucleus. To understand the functional roles of PgMYB1, we investigated the expression patterns of PgMYB1 in different tissues and under various conditions. Quantitative real-time polymerase chain reaction and western blot analysis showed that PgMYB1 was expressed at higher level in roots, leaves, and lateral roots than in stems and seeds. The expression of PgMYB1 was up-regulated by abscisic acid, salicylic acid, NaCl, and cold (chilling), and down-regulated by methyl jasmonate. These results suggest that PgMYB1 might be involved in responding to environmental stresses and hormones. PMID:25791525

  10. Effect of Biotic and Abiotic Factors on In Vitro Proliferation, Encystment, and Excystment of Pfiesteria piscicida▿ †

    PubMed Central

    Saito, Keiko; Drgon, Tomás; Krupatkina, Danara N.; Drgonova, Jana; Terlizzi, Daniel E.; Mercer, Natalia; Vasta, Gerardo R.

    2007-01-01

    Pfiesteria spp. are mixotrophic armored dinoflagellates populating the Atlantic coastal waters of the United States. They have been a focus of intense research due to their reported association with several fish mortality events. We have now used a clonal culture of Pfiesteria piscicida and several new environmental isolates to describe growth characteristics, feeding, and factors contributing to the encystment and germination of the organism in both laboratory and environmental samples. We also discuss applied methods of detection of the different morphological forms of Pfiesteria in environmental samples. In summary, Pfiesteria, when grown with its algal prey, Rhodomonas sp., presents a typical growth curve with lag, exponential, and stationary phases, followed by encystment. The doubling time in exponential phase is about 12 h. The profiles of proliferation under a standard light cycle and in the dark were similar, although the peak cell densities were markedly lower when cells were grown in the dark. The addition of urea, chicken manure, and soil extracts did not enhance Pfiesteria proliferation, but crude unfiltered spent aquarium water did. Under conditions of food deprivation or cold (4°C), Pfiesteria readily formed harvestable cysts that were further analyzed by PCR and scanning electron microscopy. The germination of Pfiesteria cysts in environmental sediment was enhanced by the presence of live fish: dinospores could be detected 13 to 15 days earlier and reached 5- to 10-times-higher peak cell densities with live fish than with artificial seawater or f/2 medium alone. The addition of ammonia, urea, nitrate, phosphate, or surprisingly, spent fish aquarium water had no effect. PMID:17704277

  11. Mulberry Transcription Factor MnDREB4A Confers Tolerance to Multiple Abiotic Stresses in Transgenic Tobacco

    PubMed Central

    Guo, Qing; Zhang, Meng; Cao, Bo-Ning; Xiang, Zhong-Huai; Zhao, Ai-Chun

    2015-01-01

    The dehydration responsive element binding (DREB) transcription factors have been reported to be involved in stress responses. Most studies have focused on DREB genes in subgroups A-1 and A-2 in herbaceous plants, but there have been few reports on the functions of DREBs from the A-3–A-6 subgroups and in woody plants. Moreover, mulberry trees are ecologically and economically important perennial woody plants, but there has been little research on its stress physiology, biochemistry and molecular biology. In this study, a DREB gene from the mulberry tree, designated as MnDREB4A, classified into the A-4 subgroup by our previous study, was selected for further characterization. Our results showed that the MnDREB4A protein was localized to the nucleus where it activated transcription. The promoter of MnDREB4A can direct prominent expression downstream of the β-glucuronidase (GUS) gene under heat, cold, drought and salt stress, and GUS staining was deepest after 12 h of stress treatment. The MnDREB4A-overexpression transgenic tobacco showed the improved growth phenotype under untreated conditions, such as greener leaves, longer roots, and lower water loss and senescence rates. Overexpression of MnDREB4A in tobacco can significantly enhance tolerance to heat, cold, drought, and salt stresses in transgenic plants. The leaf discs and seedlings of transgenic plants reduced leaf wilting and senescence rates compared to the wild type plants under the different stress conditions. Further investigation showed that transgenic plants also had higher water contents and proline contents, and lower malondialdehyde contents under untreated condition and stress conditions. Our results indicate that the MnDREB4A protein plays an important role in plant stress tolerance. PMID:26695076

  12. Mulberry Transcription Factor MnDREB4A Confers Tolerance to Multiple Abiotic Stresses in Transgenic Tobacco.

    PubMed

    Liu, Xue-Qin; Liu, Chang-Ying; Guo, Qing; Zhang, Meng; Cao, Bo-Ning; Xiang, Zhong-Huai; Zhao, Ai-Chun

    2015-01-01

    The dehydration responsive element binding (DREB) transcription factors have been reported to be involved in stress responses. Most studies have focused on DREB genes in subgroups A-1 and A-2 in herbaceous plants, but there have been few reports on the functions of DREBs from the A-3-A-6 subgroups and in woody plants. Moreover, mulberry trees are ecologically and economically important perennial woody plants, but there has been little research on its stress physiology, biochemistry and molecular biology. In this study, a DREB gene from the mulberry tree, designated as MnDREB4A, classified into the A-4 subgroup by our previous study, was selected for further characterization. Our results showed that the MnDREB4A protein was localized to the nucleus where it activated transcription. The promoter of MnDREB4A can direct prominent expression downstream of the β-glucuronidase (GUS) gene under heat, cold, drought and salt stress, and GUS staining was deepest after 12 h of stress treatment. The MnDREB4A-overexpression transgenic tobacco showed the improved growth phenotype under untreated conditions, such as greener leaves, longer roots, and lower water loss and senescence rates. Overexpression of MnDREB4A in tobacco can significantly enhance tolerance to heat, cold, drought, and salt stresses in transgenic plants. The leaf discs and seedlings of transgenic plants reduced leaf wilting and senescence rates compared to the wild type plants under the different stress conditions. Further investigation showed that transgenic plants also had higher water contents and proline contents, and lower malondialdehyde contents under untreated condition and stress conditions. Our results indicate that the MnDREB4A protein plays an important role in plant stress tolerance. PMID:26695076

  13. Diagnosing Abiotic Degradation

    EPA Science Inventory

    The abiotic degradation of chlorinated solvents in ground water can be difficult to diagnose. Under current practice, most of the “evidence” is negative; specifically the apparent disappearance of chlorinated solvents with an accumulation of vinyl chloride, ethane, ethylene, or ...

  14. Influence of abiotic stress signals on secondary metabolites in plants

    PubMed Central

    Ramakrishna, Akula; Ravishankar, Gokare Aswathanarayana

    2011-01-01

    Plant secondary metabolites are unique sources for pharmaceuticals, food additives, flavors, and industrially important biochemicals. Accumulation of such metabolites often occurs in plants subjected to stresses including various elicitors or signal molecules. Secondary metabolites play a major role in the adaptation of plants to the environment and in overcoming stress conditions. Environmental factors viz. temperature, humidity, light intensity, the supply of water, minerals, and CO2 influence the growth of a plant and secondary metabolite production. Drought, high salinity, and freezing temperatures are environmental conditions that cause adverse effects on the growth of plants and the productivity of crops. Plant cell culture technologies have been effective tools for both studying and producing plant secondary metabolites under in vitro conditions and for plant improvement. This brief review summarizes the influence of different abiotic factors include salt, drought, light, heavy metals, frost etc. on secondary metabolites in plants. The focus of the present review is the influence of abiotic factors on secondary metabolite production and some of important plant pharmaceuticals. Also, we describe the results of in vitro cultures and production of some important secondary metabolites obtained in our laboratory. PMID:22041989

  15. FACTORS AND PRACTICES THAT INFLUENCE LIVESTOCK DISTRIBUTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Inconsistent livestock distribution in extensive rangeland pastures continues as a vexing problem for land and livestock managers. Dispersal patterns of cattle are affected by abiotic factors like degree of slope, distance from water, shade, physical barriers, temperature extremes and precipitation...

  16. Improved abiotic stress tolerance of bermudagrass by exogenous small molecules.

    PubMed

    Chan, Zhulong; Shi, Haitao

    2015-01-01

    As a widely used warm-season turfgrass in landscapes and golf courses, bermudagrass encounters multiple abiotic stresses during the growth and development. Physiology analysis indicated that abiotic stresses induced the accumulation of ROS and decline of photosynthesis, resulting in increased cell damage and inhibited growth. Proteomic and metabolomic approaches showed that antioxidant enzymes and osmoprotectant contents (sugar, sucrose, dehydrin, proline) were extensively changed under abiotic stress conditions. Exogenous application of small molecules, such as ABA, NO, CaCl2, H2S, polyamine and melatonin, could effectively alleviate damages caused by multiple abiotic stresses, including drought, salt, heat and cold. Based on high through-put RNA seq analysis, genes involved in ROS, transcription factors, hormones, and carbohydrate metabolisms were largely enriched. The data indicated that small molecules induced the accumulation of osmoprotectants and antioxidants, kept cell membrane integrity, increased photosynthesis and kept ion homeostasis, which protected bermudagrass from damages caused by abiotic stresses. PMID:25757363

  17. The AaDREB1 Transcription Factor from the Cold-Tolerant Plant Adonis amurensis Enhances Abiotic Stress Tolerance in Transgenic Plant

    PubMed Central

    Zong, Jun-Mei; Li, Xiao-Wei; Zhou, Yuan-Hang; Wang, Fa-Wei; Wang, Nan; Dong, Yuan-Yuan; Yuan, Yan-Xi; Chen, Huan; Liu, Xiu-Ming; Yao, Na; Li, Hai-Yan

    2016-01-01

    Dehydration-responsive element binding (DREB) transcription factors (TFs) play important roles in the regulation of plant resistance to environmental stresses and can specifically bind to dehydration-responsive element/C-repeat element (DRE/CRT) proteins (G/ACCGAC) and activate expression of many stress-inducible genes. Here, we cloned and characterized a novel gene (AaDREB1) encoding the DREB1 transcription factor from the cold-tolerant plant Adonis amurensis. Quantitative real-time (qRT)-PCR results indicated that AaDREB1 expression was induced by salt, drought, cold stress, and abscisic acid application. A yeast one-hybrid assay demonstrated that AaDREB1 encodes a transcription activator and specifically binds to DRE/CRT. Furthermore, transgenic Arabidopsis and rice harboring AaDREB1 showed enhanced tolerance to salt, drought, and low temperature. These results indicated that AaDREB1 might be useful in genetic engineering to improve plant stress tolerance. PMID:27110776

  18. The AaDREB1 Transcription Factor from the Cold-Tolerant Plant Adonis amurensis Enhances Abiotic Stress Tolerance in Transgenic Plant.

    PubMed

    Zong, Jun-Mei; Li, Xiao-Wei; Zhou, Yuan-Hang; Wang, Fa-Wei; Wang, Nan; Dong, Yuan-Yuan; Yuan, Yan-Xi; Chen, Huan; Liu, Xiu-Ming; Yao, Na; Li, Hai-Yan

    2016-01-01

    Dehydration-responsive element binding (DREB) transcription factors (TFs) play important roles in the regulation of plant resistance to environmental stresses and can specifically bind to dehydration-responsive element/C-repeat element (DRE/CRT) proteins (G/ACCGAC) and activate expression of many stress-inducible genes. Here, we cloned and characterized a novel gene (AaDREB1) encoding the DREB1 transcription factor from the cold-tolerant plant Adonis amurensis. Quantitative real-time (qRT)-PCR results indicated that AaDREB1 expression was induced by salt, drought, cold stress, and abscisic acid application. A yeast one-hybrid assay demonstrated that AaDREB1 encodes a transcription activator and specifically binds to DRE/CRT. Furthermore, transgenic Arabidopsis and rice harboring AaDREB1 showed enhanced tolerance to salt, drought, and low temperature. These results indicated that AaDREB1 might be useful in genetic engineering to improve plant stress tolerance. PMID:27110776

  19. Biotic and Abiotic Factors Controlling Respiration Rates of Above- and Belowground Woody Debris of Fagus crenata and Quercus crispula in Japan

    PubMed Central

    Jomura, Mayuko; Akashi, Yuhei; Itoh, Hiromu; Yuki, Risa; Sakai, Yoshimi; Maruyama, Yutaka

    2015-01-01

    As a large, long-term pool and source of carbon and nutrients, woody litter is an important component of forest ecosystems. The objective of this study was to estimate the effect of the factors that regulate the rate of decomposition of coarse and fine woody debris (CFWD) of dominant tree species in a cool-temperate forest in Japan. Respiration rates of dead stems, branches, and coarse and fine roots of Fagus crenata and Quercus crispula felled 4 years prior obtained in situ ranged from 20.9 to 500.1 mg CO2 [kg dry wood]–1 h–1 in a one-time measurement in summer. Respiration rate had a significant negative relationship with diameter; in particular, that of a sample of Q. crispula with a diameter of >15 cm and substantial heartwood was low. It also had a significant positive relationship with moisture content. The explanatory variables diameter, [N], wood density, and moisture content were interrelated. The most parsimonious path model showed 14 significant correlations among 8 factors and respiration. Diameter and [C] had large negative direct effects on CFWD respiration rate, and moisture content and species had medium positive direct effects. [N] and temperature did not have direct or indirect effects, and position and wood density had indirect effects. The model revealed some interrelationships between controlling factors. We discussed the influence of the direct effects of explanatory variables and the influence especially of species and position. We speculate that the small R2 value of the most parsimonious model was probably due to the omission of microbial biomass and activity. These direct and indirect effects and interrelationships between explanatory variables could be used to develop a process-based CFWD decomposition model. PMID:26658727

  20. Biotic and Abiotic Factors Controlling Respiration Rates of Above- and Belowground Woody Debris of Fagus crenata and Quercus crispula in Japan.

    PubMed

    Jomura, Mayuko; Akashi, Yuhei; Itoh, Hiromu; Yuki, Risa; Sakai, Yoshimi; Maruyama, Yutaka

    2015-01-01

    As a large, long-term pool and source of carbon and nutrients, woody litter is an important component of forest ecosystems. The objective of this study was to estimate the effect of the factors that regulate the rate of decomposition of coarse and fine woody debris (CFWD) of dominant tree species in a cool-temperate forest in Japan. Respiration rates of dead stems, branches, and coarse and fine roots of Fagus crenata and Quercus crispula felled 4 years prior obtained in situ ranged from 20.9 to 500.1 mg CO2 [kg dry wood](-1) h(-1) in a one-time measurement in summer. Respiration rate had a significant negative relationship with diameter; in particular, that of a sample of Q. crispula with a diameter of >15 cm and substantial heartwood was low. It also had a significant positive relationship with moisture content. The explanatory variables diameter, [N], wood density, and moisture content were interrelated. The most parsimonious path model showed 14 significant correlations among 8 factors and respiration. Diameter and [C] had large negative direct effects on CFWD respiration rate, and moisture content and species had medium positive direct effects. [N] and temperature did not have direct or indirect effects, and position and wood density had indirect effects. The model revealed some interrelationships between controlling factors. We discussed the influence of the direct effects of explanatory variables and the influence especially of species and position. We speculate that the small R2 value of the most parsimonious model was probably due to the omission of microbial biomass and activity. These direct and indirect effects and interrelationships between explanatory variables could be used to develop a process-based CFWD decomposition model. PMID:26658727

  1. Genome-Wide Analysis of C2H2 Zinc-Finger Family Transcription Factors and Their Responses to Abiotic Stresses in Poplar (Populus trichocarpa)

    PubMed Central

    Liu, Quangang; Wang, Zhanchao; Xu, Xuemei; Zhang, Haizhen; Li, Chenghao

    2015-01-01

    Background C2H2 zinc-finger (C2H2-ZF) proteins are a large gene family in plants that participate in various aspects of normal plant growth and development, as well as in biotic and abiotic stress responses. To date, no overall analysis incorporating evolutionary history and expression profiling of the C2H2-ZF gene family in model tree species poplar (Populus trichocarpa) has been reported. Principal Findings Here, we identified 109 full-length C2H2-ZF genes in P. trichocarpa, and classified them into four groups, based on phylogenetic analysis. The 109 C2H2-ZF genes were distributed unequally on 19 P. trichocarpa linkage groups (LGs), with 39 segmental duplication events, indicating that segmental duplication has been important in the expansion of the C2H2-ZF gene family. Promoter cis-element analysis indicated that most of the C2H2-ZF genes contain phytohormone or abiotic stress-related cis-elements. The expression patterns of C2H2-ZF genes, based on heatmap analysis, suggested that C2H2-ZF genes are involved in tissue and organ development, especially root and floral development. Expression analysis based on quantitative real-time reverse transcription polymerase chain reaction indicated that C2H2-ZF genes are significantly involved in drought, heat and salt response, possibly via different mechanisms. Conclusions This study provides a thorough overview of the P. trichocarpa C2H2-ZF gene family and presents a new perspective on the evolution of this gene family. In particular, some C2H2-ZF genes may be involved in environmental stress tolerance regulation. PtrZFP2, 19 and 95 showed high expression levels in leaves and/or roots under environmental stresses. Additionally, this study provided a solid foundation for studying the biological roles of C2H2-ZF genes in Populus growth and development. These results form the basis for further investigation of the roles of these candidate genes and for future genetic engineering and gene functional studies in Populus. PMID

  2. Regulation of Photosynthesis during Abiotic Stress-Induced Photoinhibition.

    PubMed

    Gururani, Mayank Anand; Venkatesh, Jelli; Tran, Lam Son Phan

    2015-09-01

    Plants as sessile organisms are continuously exposed to abiotic stress conditions that impose numerous detrimental effects and cause tremendous loss of yield. Abiotic stresses, including high sunlight, confer serious damage on the photosynthetic machinery of plants. Photosystem II (PSII) is one of the most susceptible components of the photosynthetic machinery that bears the brunt of abiotic stress. In addition to the generation of reactive oxygen species (ROS) by abiotic stress, ROS can also result from the absorption of excessive sunlight by the light-harvesting complex. ROS can damage the photosynthetic apparatus, particularly PSII, resulting in photoinhibition due to an imbalance in the photosynthetic redox signaling pathways and the inhibition of PSII repair. Designing plants with improved abiotic stress tolerance will require a comprehensive understanding of ROS signaling and the regulatory functions of various components, including protein kinases, transcription factors, and phytohormones, in the responses of photosynthetic machinery to abiotic stress. Bioenergetics approaches, such as chlorophyll a transient kinetics analysis, have facilitated our understanding of plant vitality and the assessment of PSII efficiency under adverse environmental conditions. This review discusses the current understanding and indicates potential areas of further studies on the regulation of the photosynthetic machinery under abiotic stress. PMID:25997389

  3. Abiotic Buildup of Ozone

    NASA Astrophysics Data System (ADS)

    Domagal-Goldman, S. D.; Meadows, V. S.

    2010-10-01

    Two of the best biosignature gases for remote detection of life on extrasolar planets are oxygen (O2) and its photochemical byproduct, ozone (O3). The main reason for their prominence as biosignatures is that large abiotic fluxes of O2 and O3 are not considered sustainable on geological and astronomical timescales. We show here how buildup of O3 can occur on planets orbiting M stars, even in the absence of the large biological fluxes. This is possible because the destruction of O2 and O3 is driven by UV photochemistry. This chemistry is much slower on planets around these stars, due to the smaller incident UV flux. Because the destruction of these gases is slower, O3 can build up to detectable levels even if the O3 source is small. We will present atmospheric profiles of these gases for planets around AD Leo (an M dwarf) as well as spectra that show the implications for missions such as Darwin and the Terrestrial Planet Finder (TPF).

  4. Reactive oxygen species in abiotic stress signaling.

    PubMed

    Jaspers, Pinja; Kangasjärvi, Jaakko

    2010-04-01

    Reactive oxygen species (ROS) are known to accumulate during abiotic stresses, and different cellular compartments respond to them by distinctive profiles of ROS formation. In contrast to earlier views, it is becoming increasingly evident that even during stress, ROS production is not necessarily a symptom of cellular dysfunction but might represent a necessary signal in adjusting the cellular machinery to the altered conditions. ROS can modulate many signal transduction pathways, such as mitogen-activated protein kinase cascades, and ultimately influence the activity of transcription factors. However, the picture of ROS-mediated signaling is still fragmentary and the issues of ROS perception as well as the signaling specificity remain open. Here, we review some of the recent advances in plant abiotic stress signaling with emphasis on processes known to be affected heavily by ROS. PMID:20028478

  5. Water temperature-influential factors, field measurement, and data presentation

    USGS Publications Warehouse

    Stevens, Herbert H.; Ficke, John F.; Smoot, George F.

    1975-01-01

    This manual contains suggested procedures for collecting and reporting of water-temperature data on streams, lakes and reservoirs, estuaries, and ground water. Among the topics discussed are the selection of equipment and measuring sites, objectives and accuracy of measurements, and data processing and presentation. Background information on the influence of temperature on water quality and the factors influencing water temperature are also presented.

  6. Circadian regulation of abiotic stress tolerance in plants

    PubMed Central

    Grundy, Jack; Stoker, Claire; Carré, Isabelle A.

    2015-01-01

    Extremes of temperatures, drought and salinity cause widespread crop losses throughout the world and impose severe limitations on the amount of land that can be used for agricultural purposes. Hence, there is an urgent need to develop crops that perform better under such abiotic stress conditions. Here, we discuss intriguing, recent evidence that circadian clock contributes to plants’ ability to tolerate different types of environmental stress, and to acclimate to them. The clock controls expression of a large fraction of abiotic stress-responsive genes, as well as biosynthesis and signaling downstream of stress response hormones. Conversely, abiotic stress results in altered expression and differential splicing of the clock genes, leading to altered oscillations of downstream stress-response pathways. We propose a range of mechanisms by which this intimate coupling between the circadian clock and environmental stress-response pathways may contribute to plant growth and survival under abiotic stress. PMID:26379680

  7. Roles of melatonin in abiotic stress resistance in plants.

    PubMed

    Zhang, Na; Sun, Qianqian; Zhang, Haijun; Cao, Yunyun; Weeda, Sarah; Ren, Shuxin; Guo, Yang-Dong

    2015-02-01

    In recent years melatonin has emerged as a research highlight in plant studies. Melatonin has different functions in many aspects of plant growth and development. The most frequently mentioned functions of melatonin are related to abiotic stresses such as drought, radiation, extreme temperature, and chemical stresses. This review mainly focuses on the regulatory effects of melatonin when plants face harsh environmental conditions. Evidence indicates that environmental stress can increase the level of endogenous melatonin in plants. Overexpression of the melatonin biosynthetic genes elevates melatonin levels in transgenic plants. The transgenic plants show enhanced tolerance to abiotic stresses. Exogenously applied melatonin can also improve the ability of plants to tolerate abiotic stresses. The mechanisms by which melatonin alleviates abiotic stresses are discussed. PMID:25124318

  8. The Tomato Hoffman’s Anthocyaninless Gene Encodes a bHLH Transcription Factor Involved in Anthocyanin Biosynthesis That Is Developmentally Regulated and Induced by Low Temperatures

    PubMed Central

    Gao, Jianchang; Guo, Yanmei; Huang, Zejun; Du, Yongchen

    2016-01-01

    Anthocyanin pigments play many roles in plants, including providing protection against biotic and abiotic stresses. Many of the genes that mediate anthocyanin accumulation have been identified through studies of flowers and fruits; however, the mechanisms of genes involved in anthocyanin regulation in seedlings under low-temperature stimulus are less well understood. Genetic characterization of a tomato inbred line, FMTT271, which showed no anthocyanin pigmentation, revealed a mutation in a bHLH transcription factor (TF) gene, which corresponds to the ah (Hoffman's anthocyaninless) locus, and so the gene in FMTT271 at that locus was named ah. Overexpression of the wild type allele of AH in FMTT271 resulted in greater anthocyanin accumulation and increased expression of several genes in the anthocyanin biosynthetic pathway. The expression of AH and anthocyanin accumulation in seedlings was shown to be developmentally regulated and induced by low-temperature stress. Additionally, transcriptome analyses of hypocotyls and leaves from the near-isogenic lines seedlings revealed that AH not only influences the expression of anthocyanin biosynthetic genes, but also genes associated with responses to abiotic stress. Furthermore, the ah mutation was shown to cause accumulation of reactive oxidative species and the constitutive activation of defense responses under cold conditions. These results suggest that AH regulates anthocyanin biosynthesis, thereby playing a protective role, and that this function is particularly important in young seedlings that are particularly vulnerable to abiotic stresses. PMID:26943362

  9. Genome-wide analysis and expression patterns of ZF-HD transcription factors under different developmental tissues and abiotic stresses in Chinese cabbage.

    PubMed

    Wang, Wenli; Wu, Peng; Li, Ying; Hou, XiLin

    2016-06-01

    The ZF-HD gene family plays an important role in plant developmental processes and stress responses. However, the function of the ZF-HD genes in Chinese cabbage remains largely unknown. Chinese cabbage (Brassica rapa ssp. pekinensis) is a member of one of the most important leaf vegetables grown worldwide. The entire Chinese cabbage genome sequence has been determined, and more than forty thousand proteins have been identified to date. In this study, 31 ZF-HD genes were identified in Chinese cabbage. We show here that the BraZF-HD genes could be categorized into ZHD and MIF subfamilies. Among them, ZHD genes are plant-specific, nearly all intronless, and related to MINI ZINC FINGER genes that possess only the zinc finger. Phylogenetic analysis suggested that ZHDs have expanded considerably during angiosperm evolution. In addition, the ZHD group has 24 members, which is twice as much as the Arabidopsis ZHD group, indicating that the Chinese cabbage ZHD genes have been retained more frequently than other group genes. Real-time PCR analysis showed that most of BraZF-HD genes are preferentially expressed in flower. Furthermore, most of these genes are significantly induced under photoperiod or vernalization conditions, as well as abiotic stresses. Thereby implying that they may play important roles in these processes. This study provides insight into the evolution of ZF-HD genes in Chinese cabbage genome and may aid efforts to further characterize the function of these predicted ZF-HD genes in flowering and resistance. PMID:26546019

  10. Abiotic and biotic factors influencing the mobility of arsenic in groundwater of a through-flow island in the Okavango Delta, Botswana

    NASA Astrophysics Data System (ADS)

    Mladenov, Natalie; Wolski, Piotr; Hettiarachchi, Ganga M.; Murray-Hudson, Michael; Enriquez, Hersy; Damaraju, Sivaramakrishna; Galkaduwa, Madhubhashini B.; McKnight, Diane M.; Masamba, Wellington

    2014-10-01

    The Okavango Delta of Botswana is a large arid-zone wetland comprising 20,000 km2 of permanent and seasonal floodplains and over 100,000 islands. It has been shown that island groundwater can have very high dissolved arsenic (As) concentration, but the abiotic and biotic controls on As mobility are not well understood in this setting. At New Island, an island located in the seasonal swamp, dissolved As concentration increased from below detection limits in the surface water to 180 μg/L in groundwater, present as As(III) species. We investigated the relative importance of hydrologic, geochemical, and geomicrobial processes, as well as influences of recent extreme flooding events, in mobilizing and sequestering As in the shallow groundwater system under this island. Our results suggest that evapotranspiration and through-flow conditions control the location of the high arsenic zone. A combination of processes is hypothesized to control elevated As in the concentration zone of New Island: high evapotranspiration rates concentrate As and other solutes, more alkaline pH leads to desorption of arsenic or dissolution of arsenic sulfides, and formation of thioarsenic complexes acts to keep arsenic in solution. Evidence from X-ray absorption near-edge structure spectroscopy (XANES) and sulfate reducing bacteria (SRB) measurements further suggests that SRBs influence arsenic sequestration as orpiment (As2S3). Although dissolved organic matter (DOM) was not significantly correlated to dissolved As in the groundwater, our results suggest that DOM may serve as an electron donor for sulfate reduction or other microbial reactions that influence redox state and As mobility. These results have important implications for water management in the region and in other large wetland environments. The processes evaluated in this study are also relevant for arsenic removal in subsurface constructed wetland systems that may exhibit rapidly changing processes over small spatial scales.

  11. MicroRNAs As Potential Targets for Abiotic Stress Tolerance in Plants

    PubMed Central

    Shriram, Varsha; Kumar, Vinay; Devarumath, Rachayya M.; Khare, Tushar S.; Wani, Shabir H.

    2016-01-01

    The microRNAs (miRNAs) are small (20–24 nt) sized, non-coding, single stranded riboregulator RNAs abundant in higher organisms. Recent findings have established that plants assign miRNAs as critical post-transcriptional regulators of gene expression in sequence-specific manner to respond to numerous abiotic stresses they face during their growth cycle. These small RNAs regulate gene expression via translational inhibition. Usually, stress induced miRNAs downregulate their target mRNAs, whereas, their downregulation leads to accumulation and function of positive regulators. In the past decade, investigations were mainly aimed to identify plant miRNAs, responsive to individual or multiple environmental factors, profiling their expression patterns and recognizing their roles in stress responses and tolerance. Altered expressions of miRNAs implicated in plant growth and development have been reported in several plant species subjected to abiotic stress conditions such as drought, salinity, extreme temperatures, nutrient deprivation, and heavy metals. These findings indicate that miRNAs may hold the key as potential targets for genetic manipulations to engineer abiotic stress tolerance in crop plants. This review is aimed to provide recent updates on plant miRNAs, their biogenesis and functions, target prediction and identification, computational tools and databases available for plant miRNAs, and their roles in abiotic stress-responses and adaptive mechanisms in major crop plants. Besides, the recent case studies for overexpressing the selected miRNAs for miRNA-mediated enhanced abiotic stress tolerance of transgenic plants have been discussed. PMID:27379117

  12. MicroRNAs As Potential Targets for Abiotic Stress Tolerance in Plants.

    PubMed

    Shriram, Varsha; Kumar, Vinay; Devarumath, Rachayya M; Khare, Tushar S; Wani, Shabir H

    2016-01-01

    The microRNAs (miRNAs) are small (20-24 nt) sized, non-coding, single stranded riboregulator RNAs abundant in higher organisms. Recent findings have established that plants assign miRNAs as critical post-transcriptional regulators of gene expression in sequence-specific manner to respond to numerous abiotic stresses they face during their growth cycle. These small RNAs regulate gene expression via translational inhibition. Usually, stress induced miRNAs downregulate their target mRNAs, whereas, their downregulation leads to accumulation and function of positive regulators. In the past decade, investigations were mainly aimed to identify plant miRNAs, responsive to individual or multiple environmental factors, profiling their expression patterns and recognizing their roles in stress responses and tolerance. Altered expressions of miRNAs implicated in plant growth and development have been reported in several plant species subjected to abiotic stress conditions such as drought, salinity, extreme temperatures, nutrient deprivation, and heavy metals. These findings indicate that miRNAs may hold the key as potential targets for genetic manipulations to engineer abiotic stress tolerance in crop plants. This review is aimed to provide recent updates on plant miRNAs, their biogenesis and functions, target prediction and identification, computational tools and databases available for plant miRNAs, and their roles in abiotic stress-responses and adaptive mechanisms in major crop plants. Besides, the recent case studies for overexpressing the selected miRNAs for miRNA-mediated enhanced abiotic stress tolerance of transgenic plants have been discussed. PMID:27379117

  13. [Seasonal dynamics of genus Alexandrium (potentially toxic dinoflagellate) in the lagoon of Bizerte (North of Tunisia) and controls by the abiotic factors].

    PubMed

    Bouchouicha Smida, Donia; Sahraoui, Inès; Mabrouk, Hassine Hadj; Sakka Hlaili, Asma

    2012-06-01

    Some species of the genus Alexandrium are known as potential producers of saxitoxin, a neurotoxin that causes the paralytic shellfish poisoning (PSP) syndrome. Blooming of these species, especially in shellfish farms can affect the aquaculture production and harm human health. Seasonal dynamics of Alexandrium spp. abundance in relationship to environmental factors was investigated from November 2007 to February 2009 at six stations in the Bizerte lagoon, an important shellfish farming area situated in SW Mediterranean. The sampling stations represented different hydrological and trophic conditions: one station TJ (Tinja) is affected by the river plume; two stations (Chaara [Ch] and Canal [Ca]) are influenced by marine inflow (particularly in summer), industrial and urban effluents; and the three other stations (Menzel Abdelrahmen [MA], Menzel Jemil [MJ] and Douaouda [Do]) are located close to shellfish farms. Cell abundance of Alexandrium spp. varied among stations and months. Species of this genus showed a sporadic appearance, but they reached high concentration (0.67-7 × 10(5)cells L(-1)). Maximal cell density was detected in autumn (November 2007; station MA), at salinity of 37.5, temperature of 16 °C and NH(4)(+) level of 55.45 μM. During this month, Alexandrium spp. abundance accounted for a large fraction (61%) of the harmful phytoplankton. The statistical analysis revealed that Alexandrium concentrations were positively correlated with N:P ratio and NH4+ levels. Thus, the eutrophic waters of the lagoon favour the growth of Alexandrium, which seemed to have preference for N-nutrient loading from antrophogenic activities, as ammonium. Blooms of these potential harmful algae may constitute a potential threat in this coastal lagoon of the southern Mediterranean. Consequently, it is necessary to be well vigilant and to do regular monitoring of Alexandrium species. PMID:22721562

  14. Biological Networks Underlying Abiotic Stress Tolerance in Temperate Crops—A Proteomic Perspective

    PubMed Central

    Kosová, Klára; Vítámvás, Pavel; Urban, Milan Oldřich; Klíma, Miroslav; Roy, Amitava; Prášil, Ilja Tom

    2015-01-01

    Abiotic stress factors, especially low temperatures, drought, and salinity, represent the major constraints limiting agricultural production in temperate climate. Under the conditions of global climate change, the risk of damaging effects of abiotic stresses on crop production increases. Plant stress response represents an active process aimed at an establishment of novel homeostasis under altered environmental conditions. Proteins play a crucial role in plant stress response since they are directly involved in shaping the final phenotype. In the review, results of proteomic studies focused on stress response of major crops grown in temperate climate including cereals: common wheat (Triticum aestivum), durum wheat (Triticum durum), barley (Hordeum vulgare), maize (Zea mays); leguminous plants: alfalfa (Medicago sativa), soybean (Glycine max), common bean (Phaseolus vulgaris), pea (Pisum sativum); oilseed rape (Brassica napus); potato (Solanum tuberosum); tobacco (Nicotiana tabaccum); tomato (Lycopersicon esculentum); and others, to a wide range of abiotic stresses (cold, drought, salinity, heat, imbalances in mineral nutrition and heavy metals) are summarized. The dynamics of changes in various protein functional groups including signaling and regulatory proteins, transcription factors, proteins involved in protein metabolism, amino acid metabolism, metabolism of several stress-related compounds, proteins with chaperone and protective functions as well as structural proteins (cell wall components, cytoskeleton) are briefly overviewed. Attention is paid to the differences found between differentially tolerant genotypes. In addition, proteomic studies aimed at proteomic investigation of multiple stress factors are discussed. In conclusion, contribution of proteomic studies to understanding the complexity of crop response to abiotic stresses as well as possibilities to identify and utilize protein markers in crop breeding processes are discussed. PMID:26340626

  15. Biological Networks Underlying Abiotic Stress Tolerance in Temperate Crops--A Proteomic Perspective.

    PubMed

    Kosová, Klára; Vítámvás, Pavel; Urban, Milan Oldřich; Klíma, Miroslav; Roy, Amitava; Prášil, Ilja Tom

    2015-01-01

    Abiotic stress factors, especially low temperatures, drought, and salinity, represent the major constraints limiting agricultural production in temperate climate. Under the conditions of global climate change, the risk of damaging effects of abiotic stresses on crop production increases. Plant stress response represents an active process aimed at an establishment of novel homeostasis under altered environmental conditions. Proteins play a crucial role in plant stress response since they are directly involved in shaping the final phenotype. In the review, results of proteomic studies focused on stress response of major crops grown in temperate climate including cereals: common wheat (Triticum aestivum), durum wheat (Triticum durum), barley (Hordeum vulgare), maize (Zea mays); leguminous plants: alfalfa (Medicago sativa), soybean (Glycine max), common bean (Phaseolus vulgaris), pea (Pisum sativum); oilseed rape (Brassica napus); potato (Solanum tuberosum); tobacco (Nicotiana tabaccum); tomato (Lycopersicon esculentum); and others, to a wide range of abiotic stresses (cold, drought, salinity, heat, imbalances in mineral nutrition and heavy metals) are summarized. The dynamics of changes in various protein functional groups including signaling and regulatory proteins, transcription factors, proteins involved in protein metabolism, amino acid metabolism, metabolism of several stress-related compounds, proteins with chaperone and protective functions as well as structural proteins (cell wall components, cytoskeleton) are briefly overviewed. Attention is paid to the differences found between differentially tolerant genotypes. In addition, proteomic studies aimed at proteomic investigation of multiple stress factors are discussed. In conclusion, contribution of proteomic studies to understanding the complexity of crop response to abiotic stresses as well as possibilities to identify and utilize protein markers in crop breeding processes are discussed. PMID:26340626

  16. Soil respiration in the cold desert environment of the Colorado Plateau (USA): Abiotic regulators and thresholds

    USGS Publications Warehouse

    Fernandez, D.P.; Neff, J.C.; Belnap, J.; Reynolds, R.L.

    2006-01-01

    Decomposition is central to understanding ecosystem carbon exchange and nutrient-release processes. Unlike mesic ecosystems, which have been extensively studied, xeric landscapes have received little attention; as a result, abiotic soil-respiration regulatory processes are poorly understood in xeric environments. To provide a more complete and quantitative understanding about how abiotic factors influence soil respiration in xeric ecosystems, we conducted soil- respiration and decomposition-cloth measurements in the cold desert of southeast Utah. Our study evaluated when and to what extent soil texture, moisture, temperature, organic carbon, and nitrogen influence soil respiration and examined whether the inverse-texture hypothesis applies to decomposition. Within our study site, the effect of texture on moisture, as described by the inverse texture hypothesis, was evident, but its effect on decomposition was not. Our results show temperature and moisture to be the dominant abiotic controls of soil respiration. Specifically, temporal offsets in temperature and moisture conditions appear to have a strong control on soil respiration, with the highest fluxes occurring in spring when temperature and moisture were favorable. These temporal offsets resulted in decomposition rates that were controlled by soil moisture and temperature thresholds. The highest fluxes of CO2 occurred when soil temperature was between 10 and 16??C and volumetric soil moisture was greater than 10%. Decomposition-cloth results, which integrate decomposition processes across several months, support the soil-respiration results and further illustrate the seasonal patterns of high respiration rates during spring and low rates during summer and fall. Results from this study suggest that the parameters used to predict soil respiration in mesic ecosystems likely do not apply in cold-desert environments. ?? Springer 2006.

  17. Diverse roles of jasmonates and ethylene in abiotic stress tolerance.

    PubMed

    Kazan, Kemal

    2015-04-01

    Jasmonates (JAs) and ethylene (ET), often acting cooperatively, play essential roles in regulating plant defense against pests and pathogens. Recent research reviewed here has revealed mechanistic new insights into the mode of action of these hormones in plant abiotic stress tolerance. During cold stress, JAs and ET differentially regulate the C-repeat binding factor (CBF) pathway. Major JA and ET signaling hubs such as JAZ proteins, CTR1, MYC2, components of the mediator complex, EIN2, EIN3, and several members of the AP2/ERF transcription factor gene family all have complex regulatory roles during abiotic stress adaptation. Better understanding the roles of these phytohormones in plant abiotic stress tolerance will contribute to the development of crop plants tolerant to a wide range of stressful environments. PMID:25731753

  18. Temperature regulation of virulence factors in the pathogen Vibrio coralliilyticus

    PubMed Central

    Kimes, Nikole E; Grim, Christopher J; Johnson, Wesley R; Hasan, Nur A; Tall, Ben D; Kothary, Mahendra H; Kiss, Hajnalka; Munk, A Christine; Tapia, Roxanne; Green, Lance; Detter, Chris; Bruce, David C; Brettin, Thomas S; Colwell, Rita R; Morris, Pamela J

    2012-01-01

    Sea surface temperatures (SST) are rising because of global climate change. As a result, pathogenic Vibrio species that infect humans and marine organisms during warmer summer months are of growing concern. Coral reefs, in particular, are already experiencing unprecedented degradation worldwide due in part to infectious disease outbreaks and bleaching episodes that are exacerbated by increasing SST. For example, Vibrio coralliilyticus, a globally distributed bacterium associated with multiple coral diseases, infects corals at temperatures above 27 °C. The mechanisms underlying this temperature-dependent pathogenicity, however, are unknown. In this study, we identify potential virulence mechanisms using whole genome sequencing of V. coralliilyticus ATCC (American Type Culture Collection) BAA-450. Furthermore, we demonstrate direct temperature regulation of numerous virulence factors using proteomic analysis and bioassays. Virulence factors involved in motility, host degradation, secretion, antimicrobial resistance and transcriptional regulation are upregulated at the higher virulent temperature of 27 °C, concurrent with phenotypic changes in motility, antibiotic resistance, hemolysis, cytotoxicity and bioluminescence. These results provide evidence that temperature regulates multiple virulence mechanisms in V. coralliilyticus, independent of abundance. The ecological and biological significance of this temperature-dependent virulence response is reinforced by climate change models that predict tropical SST to consistently exceed 27 °C during the spring, summer and fall seasons. We propose V. coralliilyticus as a model Gram-negative bacterium to study temperature-dependent pathogenicity in Vibrio-related diseases. PMID:22158392

  19. Calibration of Gyros with Temperature Dependent Scale Factors

    NASA Technical Reports Server (NTRS)

    Belur, Sheela V.; Harman, Richard

    2001-01-01

    The general problem of gyro calibration can be stated as the estimation of the scale factors, misalignments, and drift-rate biases of the gyro using the on-orbit sensor measurements. These gyro parameters have been traditionally treated as temperature-independent in the operational flight dynamics ground systems at NASA Goddard Space Flight Center (GSFC), a scenario which has been successfully applied in the gyro calibration of a large number of missions. A significant departure from this is the Microwave Anisotropy Probe (MAP) mission where, due to the high thermal variations expected during the mission phase, it is necessary to model the scale factors as functions of temperature. This paper addresses the issue of gyro calibration for the MAP gyro model using a manufacturer-supplied model of the variation of scale factors with temperature. The problem is formulated as a least squares problem and solved using the Levenberg-Marquardt algorithm in the MATLAB(R) library function NLSQ. The algorithm was tested on simulated data with Gaussian noise for the quaternions as well as the gyro rates and was found to consistently converge close to the true values. Significant improvement in accuracy was noticed due to the estimation of the temperature-dependent scale factors as against constant scale factors.

  20. Functional Analysis of the Maize C-Repeat/DRE Motif-Binding Transcription Factor CBF3 Promoter in Response to Abiotic Stress

    PubMed Central

    Liu, Jinliang; Wang, Fengting; Yu, Gang; Zhang, Xianghui; Jia, Chengguo; Qin, Jianchun; Pan, Hongyu

    2015-01-01

    The ZmCBF3 gene is a member of AP2/ERF transcription factor family, which is a large family of plant-specific transcription factors that share a well-conserved DNA-binding domain. To understand the regulatory mechanism of ZmCBF3 gene expression, we isolated and characterized the ZmCBF3 promoter (PZmCBF3). Three deletion fragments of PZmCBF3 were generated, C1–C3, from the translation start codon at position −1079, −638, and −234, and fused to the GUS reporter gene. Each deletion construct was analyzed by Agrobacterium-mediated stable transformation and expression in Arabidopsis thaliana. GUS expression assays indicated that the PZmCBF3 exhibited root-specific expression activity. A 234-bp fragment upstream of the ZmCBF3 gene conferred a high level of GUS activity in Arabidopsis. Some cis-acting elements involved in the down-regulation of gene expression were detected in the promoter, encompassing positions −1079 to −234. PZmCBF3 was activated by cold stress. The MYCCONSENSUSAT elements (CANNTG) were responsible for the ability of PZmCBF3 to respond to cold stress. The results of the present study suggest that PZmCBF3 might play a role in cold tolerance in maize. PMID:26030672

  1. Functional Analysis of the Maize C-Repeat/DRE Motif-Binding Transcription Factor CBF3 Promoter in Response to Abiotic Stress.

    PubMed

    Liu, Jinliang; Wang, Fengting; Yu, Gang; Zhang, Xianghui; Jia, Chengguo; Qin, Jianchun; Pan, Hongyu

    2015-01-01

    The ZmCBF3 gene is a member of AP2/ERF transcription factor family, which is a large family of plant-specific transcription factors that share a well-conserved DNA-binding domain. To understand the regulatory mechanism of ZmCBF3 gene expression, we isolated and characterized the ZmCBF3 promoter (PZmCBF3). Three deletion fragments of PZmCBF3 were generated, C1-C3, from the translation start codon at position -1079, -638, and -234, and fused to the GUS reporter gene. Each deletion construct was analyzed by Agrobacterium-mediated stable transformation and expression in Arabidopsis thaliana. GUS expression assays indicated that the PZmCBF3 exhibited root-specific expression activity. A 234-bp fragment upstream of the ZmCBF3 gene conferred a high level of GUS activity in Arabidopsis. Some cis-acting elements involved in the down-regulation of gene expression were detected in the promoter, encompassing positions -1079 to -234. PZmCBF3 was activated by cold stress. The MYCCONSENSUSAT elements (CANNTG) were responsible for the ability of PZmCBF3 to respond to cold stress. The results of the present study suggest that PZmCBF3 might play a role in cold tolerance in maize. PMID:26030672

  2. Fall Colors, Temperature, and Day Length

    ERIC Educational Resources Information Center

    Burton, Stephen; Miller, Heather; Roossinck, Carrie

    2007-01-01

    Along with the bright hues of orange, red, and yellow, the season of fall represents significant changes, such as day length and temperature. These changes provide excellent opportunities for students to use science process skills to examine how abiotic factors such as weather and temperature impact organisms. In this article, the authors describe…

  3. Deviation Factor and Temperature-Compensation Factor of Simple Industrial Ultrasonic Solution-Concentration Sensor Which Automatically Eliminates Temperature Dependence

    NASA Astrophysics Data System (ADS)

    Ikeda, Kiyoshi

    2002-05-01

    In this study, the author analyzed the deviation factor and the temperature-compensation factor of a new simple ultrasonic solution-concentration sensor which automatically eliminates temperature dependence using the phase-locked loop method (PLLM) and the phase difference method (PDM). The deviation factor is an essential specification for designing a voltage-controlled oscillator (VCO), a phase detector (PD) and an acoustic cell (AC). It was proved that the deviation factor obtained using the empirical equation is always the same, regardless of the center frequency (fO) of the VCO in the PLLM and the frequency of the driving oscillator (OSC) (fD) for the transmitter in the PDM. The deviation factor for a 0.0-1.0% NaCl solution determined by both PLLM and PDM was 0.0078. Moreover, it became clear that the same temperature-compensation factor can be used for determining the concentrations of both NaCl and sugar solutions; this factor is derived from the empirical equations of sound velocity. Specifically, its value in a 0.0-1.0% NaCl solution at fO=2.15 MHz for PLLM is 3.381 kHz/°C, and that in a 0.0-5.0% sugar solution is 3.379 kHz/°C.

  4. Establishment of non-native plant species after wildfires: Effects of fuel treatments, abiotic and biotic factors, and post-fire grass seeding treatments

    USGS Publications Warehouse

    Hunter, M.E.; Omi, P.N.; Martinson, E.J.; Chong, G.W.

    2006-01-01

    Establishment and spread of non-native species following wildfires can pose threats to long-term native plant recovery. Factors such as disturbance severity, resource availability, and propagule pressure may influence where non-native species establish in burned areas. In addition, pre- and post-fire management activities may influence the likelihood of non-native species establishment. In the present study we examine the establishment of non-native species after wildfires in relation to native species richness, fire severity, dominant native plant cover, resource availability, and pre- and post-fire management actions (fuel treatments and post-fire rehabilitation treatments). We used an information-theoretic approach to compare alternative hypotheses. We analysed post-fire effects at multiple scales at three wildfires in Colorado and New Mexico. For large and small spatial scales at all fires, fire severity was the most consistent predictor of non-native species cover. Non-native species cover was also correlated with high native species richness, low native dominant species cover, and high seeded grass cover. There was a positive, but non-significant, association of non-native species with fuel-treated areas at one wildfire. While there may be some potential for fuels treatments to promote non-native species establishment, wildfire and post-fire seeding treatments seem to have a larger impact on non-native species. ?? IAWF 2006.

  5. Temperature can interact with landscape factors to affect songbird productivity.

    PubMed

    Cox, W Andrew; Thompson, Frank R; Reidy, Jennifer L; Faaborg, John

    2013-04-01

    Increased temperatures and more extreme weather patterns associated with global climate change can interact with other factors that regulate animal populations, but many climate change studies do not incorporate other threats to wildlife in their analyses. We used 20 years of nest-monitoring data from study sites across a gradient of habitat fragmentation in Missouri, USA, to investigate the relative influence of weather variables (temperature and precipitation) and landscape factors (forest cover and edge density) on the number of young produced per nest attempt (i.e., productivity) for three species of songbirds. We detected a strong forest cover × temperature interaction for the Acadian Flycatcher (Empidonax virescens) on productivity. Greater forest cover resulted in greater productivity because of reduced brood parasitism and increased nest survival, whereas greater temperatures reduced productivity in highly forested landscapes because of increased nest predation but had no effect in less forested landscapes. The Indigo Bunting (Passerina cyanea) exhibited a similar pattern, albeit with a marginal forest cover × temperature interaction. By contrast, productivity of the Northern Cardinal (Cardinalis cardinalis) was not influenced by landscape effects or temperature. Our results highlight a potential difficulty of managing wildlife in response to global change such as habitat fragmentation and climate warming, as the habitat associated with the greatest productivity for flycatchers was also that most negatively influenced by high temperatures. The influence of high temperatures on nest predation (and therefore, nest predators) underscores the need to acknowledge the potential complexity of species' responses to climate change by incorporating a more thorough consideration of community ecology in the development of models of climate impacts on wildlife. PMID:23504884

  6. Patterns of maximum body size evolution in Cenozoic land mammals: eco-evolutionary processes and abiotic forcing

    PubMed Central

    Saarinen, Juha J.; Boyer, Alison G.; Brown, James H.; Costa, Daniel P.; Ernest, S. K. Morgan; Evans, Alistair R.; Fortelius, Mikael; Gittleman, John L.; Hamilton, Marcus J.; Harding, Larisa E.; Lintulaakso, Kari; Lyons, S. Kathleen; Okie, Jordan G.; Sibly, Richard M.; Stephens, Patrick R.; Theodor, Jessica; Uhen, Mark D.; Smith, Felisa A.

    2014-01-01

    There is accumulating evidence that macroevolutionary patterns of mammal evolution during the Cenozoic follow similar trajectories on different continents. This would suggest that such patterns are strongly determined by global abiotic factors, such as climate, or by basic eco-evolutionary processes such as filling of niches by specialization. The similarity of pattern would be expected to extend to the history of individual clades. Here, we investigate the temporal distribution of maximum size observed within individual orders globally and on separate continents. While the maximum size of individual orders of large land mammals show differences and comprise several families, the times at which orders reach their maximum size over time show strong congruence, peaking in the Middle Eocene, the Oligocene and the Plio-Pleistocene. The Eocene peak occurs when global temperature and land mammal diversity are high and is best explained as a result of niche expansion rather than abiotic forcing. Since the Eocene, there is a significant correlation between maximum size frequency and global temperature proxy. The Oligocene peak is not statistically significant and may in part be due to sampling issues. The peak in the Plio-Pleistocene occurs when global temperature and land mammal diversity are low, it is statistically the most robust one and it is best explained by global cooling. We conclude that the macroevolutionary patterns observed are a result of the interplay between eco-evolutionary processes and abiotic forcing. PMID:24741007

  7. Abiotic stress in crops: candidate genes, osmolytes, polyamines and biotechnological intervention

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural production and quality are adversely affected by various abiotic stresses including water deficit conditions (drought), salinity, extreme temperatures (heat, cold), light intensities beyond those saturating for photosynthesis and radiation (UVB,C). This is exacerbated when such exposure...

  8. Abiotic Organic Chemistry in Hydrothermal Systems.

    NASA Astrophysics Data System (ADS)

    Simoneit, B. R.; Rushdi, A. I.

    2004-12-01

    Abiotic organic chemistry in hydrothermal systems is of interest to biologists, geochemists and oceanographers. This chemistry consists of thermal alteration of organic matter and minor prebiotic synthesis of organic compounds. Thermal alteration has been extensively documented to yield petroleum and heavy bitumen products from contemporary organic detritus. Carbon dioxide, carbon monoxide, ammonia and sulfur species have been used as precursors in prebiotic synthesis experiments to organic compounds. These inorganic species are common components of hot spring gases and marine hydrothermal systems. It is of interest to further test their reactivities in reductive aqueous thermolysis. We have synthesized organic compounds (lipids) in aqueous solutions of oxalic acid, and with carbon disulfide or ammonium bicarbonate at temperatures from 175-400° C. The synthetic lipids from oxalic acid solutions consisted of n-alkanols, n-alkanoic acids, n-alkyl formates, n-alkanones, n-alkenes and n-alkanes, typically to C30 with no carbon number preferences. The products from CS2 in acidic aqueous solutions yielded cyclic thioalkanes, alkyl polysulfides, and thioesters with other numerous minor compounds. The synthesis products from oxalic acid and ammonium bicarbonate solutions were homologous series of n-alkyl amides, n-alkyl amines, n-alkanes and n-alkanoic acids, also to C30 with no carbon number predominance. Condensation (dehydration) reactions also occur under elevated temperatures in aqueous medium as tested by model reactions to form amide, ester and nitrile bonds. It is concluded that the abiotic formation of aliphatic lipids, condensation products (amides, esters, nitriles, and CS2 derivatives (alkyl polysulfides, cyclic polysulfides) is possible under hydrothermal conditions and warrants further studies.

  9. Dynamical structure factor of magnetic Bloch oscillations at finite temperatures

    NASA Astrophysics Data System (ADS)

    Syljuåsen, Olav F.

    2015-10-01

    Domain-walls in one-dimensional Ising ferromagnets can undergo Bloch oscillations when subjected to a skew magnetic field. Such oscillations imply finite temperature non-dispersive low-frequency peaks in the dynamical structure factor which can be probed in neutron scattering. We study in detail the spectral weight of these peaks. Using an analytical approach based on an approximate treatment of a gas of spin-cluster excitations we give an explicit expression for the momentum- and temperature-dependence of the spectral weights. Generally the spectral weights increase with temperature T and approaches the same order of magnitude as the spin-wave spectral weights at high temperatures. We compare the analytical expression to numerical exact diagonalizations and find that it can, without any adjustable parameters, account for the T and momentum-transfer dependence of the numerically obtained spectral weights in the parameter regime where the ratio of magnetic fields h x / h z ≪ 1 and the temperature is h x < T < ˜ J z /2. We also carry out numerical calculations pertinent to the material CoNb2O6, and find qualitatively similar results.

  10. Abiotic Methane Synthesis: Caveats and New Results

    NASA Astrophysics Data System (ADS)

    Zou, R.; Sharma, A.

    2005-12-01

    The role of mineral interaction with geochemical fluids under hydrothermal conditions has invoked models of geochemical synthesis of organic molecules at deep crustal conditions. Since Thomas Gold's (1992) hypothesis of the possibility of an abiotic organic synthesis, there have been several reports of hydrocarbon formation under high pressure and temperature conditions. Several previous experimental studies have recognized that small amounts of methane (and other light HC compounds) can be synthesized via catalysis by transition metals: Fe, Ni (Horita and Berndt, 1999 Science) and Cr (Foustavous and Seyfried, 2004 Science). In light of these pioneering experiments, an investigation of the feasibility of abiotic methane synthesis at higher pressure conditions in deep geological setting and the possible role of catalysis warrants a closer look. We conducted three sets of experiments in hydrothermal diamond anvil cell using FeO nanopowder, CaCO 3 and water at 300° - 600° C and 0.5 - 5 GPa : (a) with stainless steel gasket, (b) gold-lined gasket, and (c) gold-lined gasket with added Fe and Ni nanopowder. The reactions were monitored in-situ using micro-Raman spectroscopy with 532nm and 632nm lasers. The solids phases were characterized in-situ using synchrotron X-ray diffraction at CHESS-Cornell and quenched products with an electron microprobe. Interestingly, a variable amount of hydrocarbon was observed only in runs with stainless steel gasket and with Fe, Ni nanoparticles. Experiments with gold-lined reactors did not show any hydrocarbon formation. Added high resolution microscopy of the products and their textural relationship within the diamond cell with Raman spectroscopy data show that the hydrocarbon (methane and other light fractions) synthesis is a direct result of transition metal catalysis, rather than wustite - calcium carbonate reaction as recently reported by Scott et al (2004, PNAS). The author will further present new results highlighting abiotic

  11. Adaptation to abiotic conditions drives local adaptation in bacteria and viruses coevolving in heterogeneous environments

    PubMed Central

    Scanlan, Pauline D.; Buckling, Angus

    2016-01-01

    Parasite local adaptation, the greater performance of parasites on their local compared with foreign hosts, has important consequences for the maintenance of diversity and epidemiology. While the abiotic environment may significantly affect local adaptation, most studies to date have failed either to incorporate the effects of the abiotic environment, or to separate them from those of the biotic environment. Here, we tease apart biotic and abiotic components of local adaptation using the bacterium Pseudomonas fluorescens and its viral parasite bacteriophage Φ2. We coevolved replicate populations of bacteria and phages at three different temperatures, and determined their performance against coevolutionary partners from the same and different temperatures. Crucially, we measured performance at different assay temperatures, which allowed us to disentangle adaptation to biotic and abiotic habitat components. Our results show that bacteria and phages are more resistant and infectious, respectively, at the temperature at which they previously coevolved, confirming that local adaptation to abiotic conditions can play a crucial role in determining parasite infectivity and host resistance. Our work underlines the need to assess host–parasite interactions across multiple relevant abiotic environments, and suggests that microbial adaption to local temperatures can create ecological barriers to dispersal across temperature gradients. PMID:26888914

  12. A membraneless single compartment abiotic glucose fuel cell

    NASA Astrophysics Data System (ADS)

    Slaughter, Gymama; Sunday, Joshua

    2014-09-01

    A simple energy harvesting strategy has been developed to selectively catalyze glucose in the presence of oxygen in a glucose/O2 fuel cell. The anode consists of an abiotic catalyst Al/Au/ZnO, in which ZnO seed layer was deposited on the surface of Al/Au substrate using hydrothermal method. The cathode is constructed from a single rod of platinum with an outer diameter of 500 μm. The abiotic glucose fuel cell was studied in phosphate buffer solution (pH 7.4) containing 5 mM glucose at a temperature of 22 °C. The cell is characterized according to its open-circuit voltage, polarization profile, and power density plot. Under these conditions, the abiotic glucose fuel cell possesses an open-circuit voltage of 840 mV and delivered a maximum power density of 16.2 μW cm-2 at a cell voltage of 495 mV. These characteristics are comparable to biofuel cell utilizing a much more complex system design. Such low-cost lightweight abiotic catalyzed glucose fuel cells have a great promise to be optimized, miniaturized to power bio-implantable devices.

  13. Physical factors in cataractogenesis: ambient ultraviolet radiation and temperature

    SciTech Connect

    Sliney, D.H.

    1986-05-01

    A number of environmental cofactors have been implicated in cataracto-genesis. Two have received the greatest attention: ultraviolet radiation (UVR) and ambient temperature. Unfortunately, both temperature and UVR levels vary similarly with geographical latitude. Careful attention to several more refined physical variables and the geometry of exposure may permit investigators to separate the contributory effects of these two physical agents. This paper briefly reviews the available data, estimates the variation of lenticular temperature with ambient temperature, and provides measurements of short-wavelength (UV-B) UVR exposure to the human eye with different meterological conditions. The study attempts to provide epidemiological investigators with more detailed information necessary to perform more accurate studies of cataract and other ocular pathologies that appear to be related to environmental factors. Ocular UV-B radiation exposure levels were measured at nine locations in the USA near 40 degrees latitude at elevations from sea level to 8000 ft. Terrain reflectance is shown to be much more important than terrain elevation; cloud cover and haze may actually increase ocular exposure; and the value of wearing brimmed hats and spectacles varies with the environment. Several avenues for future research are suggested.

  14. Separating temperature from other factors in phenological measurements

    NASA Astrophysics Data System (ADS)

    Schwartz, Mark D.; Hanes, Jonathan M.; Liang, Liang

    2014-09-01

    Phenological observations offer a simple and effective way to measure climate change effects on the biosphere. While some species in northern mixed forests show a highly sensitive site preference to microenvironmental differences (i.e., the species is present in certain areas and absent in others), others with a more plastic environmental response (e.g., Acer saccharum, sugar maple) allow provisional separation of the universal "background" phenological variation caused by in situ (possibly biological/genetic) variation from the microclimatic gradients in air temperature. Moran's I tests for spatial autocorrelation among the phenological data showed significant ( α ≤ 0.05) clustering across the study area, but random patterns within the microclimates themselves, with isolated exceptions. In other words, the presence of microclimates throughout the study area generally results in spatial autocorrelation because they impact the overall phenological development of sugar maple trees. However, within each microclimate (where temperature conditions are relatively uniform) there is little or no spatial autocorrelation because phenological differences are due largely to randomly distributed in situ factors. The phenological responses from 2008 and 2009 for two sugar maple phenological stages showed the relationship between air temperature degree-hour departure and phenological change ranged from 0.5 to 1.2 days earlier for each additional 100 degree-hours. Further, the standard deviations of phenological event dates within individual microclimates (for specific events and years) ranged from 2.6 to 3.8 days. Thus, that range of days is inferred to be the "background" phenological variation caused by factors other than air temperature variations, such as genetic differences between individuals.

  15. Integrating omic approaches for abiotic stress tolerance in soybean

    PubMed Central

    Deshmukh, Rupesh; Sonah, Humira; Patil, Gunvant; Chen, Wei; Prince, Silvas; Mutava, Raymond; Vuong, Tri; Valliyodan, Babu; Nguyen, Henry T.

    2014-01-01

    Soybean production is greatly influenced by abiotic stresses imposed by environmental factors such as drought, water submergence, salt, and heavy metals. A thorough understanding of plant response to abiotic stress at the molecular level is a prerequisite for its effective management. The molecular mechanism of stress tolerance is complex and requires information at the omic level to understand it effectively. In this regard, enormous progress has been made in the omics field in the areas of genomics, transcriptomics, and proteomics. The emerging field of ionomics is also being employed for investigating abiotic stress tolerance in soybean. Omic approaches generate a huge amount of data, and adequate advancements in computational tools have been achieved for effective analysis. However, the integration of omic-scale information to address complex genetics and physiological questions is still a challenge. In this review, we have described advances in omic tools in the view of conventional and modern approaches being used to dissect abiotic stress tolerance in soybean. Emphasis was given to approaches such as quantitative trait loci (QTL) mapping, genome-wide association studies (GWAS), and genomic selection (GS). Comparative genomics and candidate gene approaches are also discussed considering identification of potential genomic loci, genes, and biochemical pathways involved in stress tolerance mechanism in soybean. This review also provides a comprehensive catalog of available online omic resources for soybean and its effective utilization. We have also addressed the significance of phenomics in the integrated approaches and recognized high-throughput multi-dimensional phenotyping as a major limiting factor for the improvement of abiotic stress tolerance in soybean. PMID:24917870

  16. Genetic diversity in pollen abiotic stress tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genetic diversity in reproductive abiotic stress tolerance has been investigated by cotton breeders throughout the public and private sectors. The primary focus of these studies has been the evaluation of abiotic stress responses during the development of the flower prior to anthesis. Sterility in...

  17. Genetic Diversity in Pollen Abiotic Stress Tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genetic diversity in reproductive abiotic stress tolerance has been investigated by cotton breeders throughout the public and private sectors. The primary focus of these studies has been the evaluation of abiotic stress responses during the development of the flower prior to anthesis. Sterility in...

  18. 49 CFR 192.115 - Temperature derating factor (T) for steel pipe.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Temperature derating factor (T) for steel pipe... § 192.115 Temperature derating factor (T) for steel pipe. The temperature derating factor to be used in the design formula in § 192.105 is determined as follows: Gas temperature in degrees...

  19. 49 CFR 192.115 - Temperature derating factor (T) for steel pipe.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Temperature derating factor (T) for steel pipe... § 192.115 Temperature derating factor (T) for steel pipe. The temperature derating factor to be used in the design formula in § 192.105 is determined as follows: Gas temperature in...

  20. 49 CFR 192.115 - Temperature derating factor (T) for steel pipe.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Temperature derating factor (T) for steel pipe... § 192.115 Temperature derating factor (T) for steel pipe. The temperature derating factor to be used in the design formula in § 192.105 is determined as follows: Gas temperature in...

  1. 49 CFR 192.115 - Temperature derating factor (T) for steel pipe.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Temperature derating factor (T) for steel pipe... § 192.115 Temperature derating factor (T) for steel pipe. The temperature derating factor to be used in the design formula in § 192.105 is determined as follows: Gas temperature in...

  2. Microarray: gateway to unravel the mystery of abiotic stresses in plants.

    PubMed

    Gul, Ambreen; Ahad, Ammara; Akhtar, Sidra; Ahmad, Zarnab; Rashid, Bushra; Husnain, Tayyab

    2016-04-01

    Environmental factors, such as drought, salinity, extreme temperature, ozone poisoning, metal toxicity etc., significantly affect crops. To study these factors and to design a possible remedy, biological experimental data concerning these crops requires the quantification of gene expression and comparative analyses at high throughput level. Development of microarrays is the platform to study the differential expression profiling of the targeted genes. This technology can be applied to gene expression studies, ranging from individual genes to whole genome level. It is now possible to perform the quantification of the differential expression of genes on a glass slide in a single experiment. This review documents recently published reports on the use of microarrays for the identification of genes in different plant species playing their role in different cellular networks under abiotic stresses. The regulation pattern of differentially-expressed genes, individually or in group form, may help us to study different pathways and functions at the cellular and molecular level. These studies can provide us with a lot of useful information to unravel the mystery of abiotic stresses in important crop plants. PMID:26667130

  3. Polyamines and abiotic stress tolerance in plants

    PubMed Central

    Gill, Sarvajeet Singh

    2010-01-01

    Environmental stresses including climate change, especially global warming, are severely affecting plant growth and productivity worldwide. It has been estimated that two-thirds of the yield potential of major crops are routinely lost due to the unfavorable environmental factors. On the other hand, the world population is estimated to reach about 10 billion by 2050, which will witness serious food shortages. Therefore, crops with enhanced vigour and high tolerance to various environmental factors should be developed to feed the increasing world population. Maintaining crop yields under adverse environmental stresses is probably the major challenge facing modern agriculture where polyamines can play important role. Polyamines (PAs)(putrescine, spermidine and spermine) are group of phytohormone-like aliphatic amine natural compounds with aliphatic nitrogen structure and present in almost all living organisms including plants. Evidences showed that polyamines are involved in many physiological processes, such as cell growth and development and respond to stress tolerance to various environmental factors. In many cases the relationship of plant stress tolerance was noted with the production of conjugated and bound polyamines as well as stimulation of polyamine oxidation. Therefore, genetic manipulation of crop plants with genes encoding enzymes of polyamine biosynthetic pathways may provide better stress tolerance to crop plants. Furthermore, the exogenous application of PAs is also another option for increasing the stress tolerance potential in plants. Here, we have described the synthesis and role of various polyamines in abiotic stress tolerance in plants. PMID:20592804

  4. Effects of temperature on rates and mineral products of microbial Fe(II) oxidation by Leptothrix cholodnii at microaerobic conditions

    NASA Astrophysics Data System (ADS)

    Vollrath, Susann; Behrends, Thilo; Koch, Christian Bender; Cappellen, Philippe Van

    2013-05-01

    Oxygen concentrations are important in constraining the geochemical niche of neutrophilic iron oxidizers. However, other factors like temperature may affect the competition between microbial and abiotic Fe(II) oxidation and may cause community changes. Here, rates and mineral products of Fe(II) oxidation (initial concentration 150 μmol Fe(II)/l) by the Fe(II) oxidizing bacterial strain Leptothrix cholodnii Appels were compared to those of abiotic oxidation in the temperature range 11-37 °C. Experiments were carried out in a batch reactor at 12-13 μmol O2/l (0.92-1% O2 saturation), pH 7 and, for the microbial experiments, a cell density of around 108 cells/ml. The iron precipitates formed at the different temperatures were characterized by SEM, XRD, FTIR and Mössbauer spectroscopy. Abiotic and microbial Fe(II) oxidation proceeded in two stages. During the initial stage, rates of microbial oxidation exhibited a temperature optimum curve. In contrast, the temperature dependency of abiotic Fe(II) oxidation rate followed the Arrhenius equation. As a consequence, microbial oxidation rates were about 10 times higher compared to the abiotic oxidation at 30 °C. During the second stage, microbial and abiotic rates and their temperature dependencies were similar. Independent of temperature or presence of bacteria, lepidocrocite and ferrihydrite were identified as reaction products, but the characteristics of the precipitates differed. At 37 °C, less lepidocrocite was precipitated in microbial and abiotic experiments due to high oxidation rates. Abiotic oxidation produced larger lepidocrocite crystals mixed with smaller, less crystalline oxides. Large crystals were absent in the microbial products, possibly due to growth inhibition of the minerals by EPS substances. Nevertheless, Mössbauer spectra revealed a better crystal structure of the smaller, microbial precipitates compared to the abiotically formed oxides.

  5. Factors affecting characterization of bulk high-temperature superconductors

    SciTech Connect

    Hull, J.R.

    1997-11-01

    Three major factors affect the characterization of bulk high-temperature superconductors in terms of their levitation properties during interaction with permanent magnets. First, the appropriate parameter for the permanent magnet is internal magnetization, not the value of the magnetic field measured at the magnet`s surface. Second, although levitation force grows with superconductor thickness and surface area, for a given permanent magnet size, comparison of levitation force between samples is meaningful when minimum values are assigned to the superconductor size parameters. Finally, the effect of force creep must be considered when time-averaging the force measurements. In addition to levitational force, the coefficient of friction of a levitated rotating permanent magnet may be used to characterize the superconductor.

  6. Arbuscular mycorrhizal fungal responses to abiotic stresses: A review.

    PubMed

    Lenoir, Ingrid; Fontaine, Joël; Lounès-Hadj Sahraoui, Anissa

    2016-03-01

    The majority of plants live in close collaboration with a diversity of soil organisms among which arbuscular mycorrhizal fungi (AMF) play an essential role. Mycorrhizal symbioses contribute to plant growth and plant protection against various environmental stresses. Whereas the resistance mechanisms induced in mycorrhizal plants after exposure to abiotic stresses, such as drought, salinity and pollution, are well documented, the knowledge about the stress tolerance mechanisms implemented by the AMF themselves is limited. This review provides an overview of the impacts of various abiotic stresses (pollution, salinity, drought, extreme temperatures, CO2, calcareous, acidity) on biodiversity, abundance and development of AMF and examines the morphological, biochemical and molecular mechanisms implemented by AMF to survive in the presence of these stresses. PMID:26803396

  7. Demonstration of significant abiotic iron isotope fractionation in nature

    USGS Publications Warehouse

    Bullen, T.D.; White, A.F.; Childs, C.W.; Vivit, D.V.; Schultz, M.S.

    2001-01-01

    Field and laboratory studies reveal that the mineral ferrihydrite, formed as a result of abiotic oxidation of aqueous ferrous to ferric Fe, contains Fe that is isotopically heavy relative to coexisting aqueous Fe. Because the electron transfer step of the oxidation process at pH >5 is essentially irreversible and should favor the lighter Fe isotopes in the ferric iron product, this result suggests that relatively heavy Fe isotopes are preferentially partitioned into the readily oxidized Fe(II)(OH)x(aq) species or their transition complexes prior to oxidation. The apparent Fe isotope fractionation factor, ??ferrihydrite-water, depends primarily on the relative abundances of the Fe(II)(aq) species. This study demonstrates that abiotic processes can fractionate the Fe isotopes to the same extent as biotic processes, and thus Fe isotopes on their own do not provide an effective biosignature.

  8. 49 CFR 192.115 - Temperature derating factor (T) for steel pipe.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Temperature derating factor (T) for steel pipe. 192.115 Section 192.115 Transportation Other Regulations Relating to Transportation (Continued... § 192.115 Temperature derating factor (T) for steel pipe. The temperature derating factor to be used...

  9. Abiotic gas formation drives nitrogen loss from a desert ecosystem.

    PubMed

    McCalley, Carmody K; Sparks, Jed P

    2009-11-01

    In arid environments such as deserts, nitrogen is often the most limiting nutrient for biological activity. The majority of the ecosystem nitrogen flux is typically thought to be driven by production and loss of reactive nitrogen species by microorganisms in the soil. We found that high soil-surface temperatures (greater than 50 degrees C), driven by solar radiation, are the primary cause of nitrogen loss in Mojave Desert soils. This abiotic pathway not only enables the balancing of arid ecosystem nitrogen budgets, but also changes our view of global nitrogen cycling and the predicted impact of climate change and increased temperatures on nitrogen bioavailability. PMID:19892980

  10. Analysis and modeling for fiber-optic gyroscope scale factor based on environment temperature.

    PubMed

    Shen, Chong; Chen, Xiyuan

    2012-05-10

    To explore and reduce the nonlinear error and temperature dependency of fiber-optic gyroscope (FOG) scale factor, a scale factor modeling method based on temperature is presented in this paper. A hyperbolic curve fitting is proposed according to the characteristic of scale factor under stable temperature at first. Compared to traditional modeling methods, it shows that a higher precision model of scale factor can be obtained. Then the influence of temperature on scale factor is analyzed and then the hyperbolic curve fitting method is extended based on temperature, making it possible to work over the whole potential temperature range of the FOG without degrading the performance. This paper also provides the experimental and verification results. It can be seen that a high precision model of scale factor has been established, the temperature dependency of scale factor has been reduced effectively, and the error due to environment temperature is reduced by one order at least. PMID:22614471

  11. Biotic and abiotic controls of argentine ant invasion success at local and landscape scales

    USGS Publications Warehouse

    Menke, S.B.; Fisher, R.N.; Jetz, W.; Holway, D.A.

    2007-01-01

    Although the ecological success of introduced species hinges on biotic interactions and physical conditions, few experimental studies - especially on animals - have simultaneously investigated the relative importance of both types of factors. The lack of such research may stem from the common assumption that native and introduced species exhibit similar environmental tolerances. Here we combine experimental and spatial modeling approaches (1) to determine the relative importance of biotic and abiotic controls of Argentine ant (Linepithema humile) invasion success, (2) to examine how the importance of these factors changes with spatial scale in southern California (USA), and (3) to assess how Argentine ants differ from native ants in their environmental tolerances. A factorial field experiment that combined native ant removal with irrigation revealed that Argentine ants failed to invade any dry plots (even those lacking native ants) but readily invaded all moist plots. Native ants slowed the spread of Argentine ants into irrigated plots but did not prevent invasion. In areas without Argentine ants, native ant species showed variable responses to irrigation. At the landscape scale, Argentine ant occurrence was positively correlated with minimum winter temperature (but not precipitation), whereas native ant diversity increased with precipitation and was negatively correlated with minimum winter temperature. These results are of interest for several reasons. First, they demonstrate that fine-scale differences in the physical environment can eclipse biotic resistance from native competitors in determining community susceptibility to invasion. Second, our results illustrate surprising complexities with respect to how the abiotic factors limiting invasion can change with spatial scale, and third, how native and invasive species can differ in their responses to the physical environment. Idiosyncratic and scale-dependent processes complicate attempts to forecast where

  12. Identification and expression analysis of WRKY family genes under biotic and abiotic stresses in Brassica rapa.

    PubMed

    Kayum, Md Abdul; Jung, Hee-Jeong; Park, Jong-In; Ahmed, Nasar Uddin; Saha, Gopal; Yang, Tae-Jin; Nou, Ill-Sup

    2015-02-01

    WRKY proteins constitute one of the largest transcription factor families in higher plants, and they are involved in multiple biological processes such as plant development, metabolism, and responses to biotic and abiotic stresses. Genes of this family have been well documented in response to many abiotic and biotic stresses in many plant species, but not yet against Pectobacterium carotovorum subsp. carotovorum and Fusarium oxysporum f.sp. conglutinans in any of the plants. Moreover, potentiality of a specific gene may vary depending on stress conditions and genotypes. To identify stress resistance-related potential WRKY genes of Brassica rapa, we analyzed their expressions against above-mentioned pathogens and cold, salt, and drought stresses in B. rapa. Stress resistance-related functions of all Brassica rapa WRKY (BrWRKY) genes were firstly analyzed through homology study with existing biotic and abiotic stress resistance-related WRKY genes of other plant species and found a high degree of homology. We then identified all BrWRKY genes in a Br135K microarray dataset, which was created by applying low-temperature stresses to two contrasting Chinese cabbage doubled haploid (DH) lines, Chiifu and Kenshin, and selected 41 BrWRKY genes with high and differential transcript abundance levels. These selected genes were further investigated under cold, salt, and drought stresses as well as after infection with P. carotovorum subsp. carotovorum and F. oxysporum f.sp. conglutinans in B. rapa. The selected genes showed an organ-specific expression, and 22 BrWRKY genes were differentially expressed in Chiifu compared to Kenshin under cold and drought stresses. Six BrWRKY genes were more responsive in Kenshin compared to Chiffu under salt stress. In addition, eight BrWRKY genes showed differential expression after P. carotovorum subsp. carotovorum infection and five genes after F. oxysporum f.sp. conglutinans infection in B. rapa. Thus, the differentially expressed Br

  13. Lipid signalling in plant responses to abiotic stress.

    PubMed

    Hou, Quancan; Ufer, Guido; Bartels, Dorothea

    2016-05-01

    Lipids are one of the major components of biological membranes including the plasma membrane, which is the interface between the cell and the environment. It has become clear that membrane lipids also serve as substrates for the generation of numerous signalling lipids such as phosphatidic acid, phosphoinositides, sphingolipids, lysophospholipids, oxylipins, N-acylethanolamines, free fatty acids and others. The enzymatic production and metabolism of these signalling molecules are tightly regulated and can rapidly be activated upon abiotic stress signals. Abiotic stress like water deficit and temperature stress triggers lipid-dependent signalling cascades, which control the expression of gene clusters and activate plant adaptation processes. Signalling lipids are able to recruit protein targets transiently to the membrane and thus affect conformation and activity of intracellular proteins and metabolites. In plants, knowledge is still scarce of lipid signalling targets and their physiological consequences. This review focuses on the generation of signalling lipids and their involvement in response to abiotic stress. We describe lipid-binding proteins in the context of changing environmental conditions and compare different approaches to determine lipid-protein interactions, crucial for deciphering the signalling cascades. PMID:26510494

  14. Overexpression of a novel cold-responsive transcript factor LcFIN1 from sheepgrass enhances tolerance to low temperature stress in transgenic plants.

    PubMed

    Gao, Qiong; Li, Xiaoxia; Jia, Junting; Zhao, Pincang; Liu, Panpan; Liu, Zhujiang; Ge, Liangfa; Chen, Shuangyan; Qi, Dongmei; Deng, Bo; Lee, Byung-Hyun; Liu, Gongshe; Cheng, Liqin

    2016-03-01

    As a perennial forage crop broadly distributed in eastern Eurasia, sheepgrass (Leymus chinensis (Trin.) Tzvel) is highly tolerant to low-temperature stress. Previous report indicates that sheepgrass is able to endure as low as -47.5 °C,allowing it to survive through the cold winter season. However, due to the lack of sufficient studies, the underlying mechanism towards the extraordinary low-temperature tolerance is unclear. Although the transcription profiling has provided insight into the transcriptome response to cold stress, more detailed studies are required to dissect the molecular mechanism regarding the excellent abiotic stress tolerance. In this work, we report a novel transcript factor LcFIN1 (L. chinensis freezing-induced 1) from sheepgrass. LcFIN1 showed no homology with other known genes and was rapidly and highly induced by cold stress, suggesting that LcFIN1 participates in the early response to cold stress. Consistently, ectopic expression of LcFIN1 significantly increased cold stress tolerance in the transgenic plants, as indicated by the higher survival rate, fresh weight and other stress-related indexes after a freezing treatment. Transcriptome analysis showed that numerous stress-related genes were differentially expressed in LcFIN1-overexpressing plants, suggesting that LcFIN1 may enhance plant abiotic stress tolerance by transcriptional regulation. Electrophoretic mobility shift assays and CHIP-qPCR showed that LcCBF1 can bind to the CRT/DRE cis-element located in the promoter region of LcFIN1, suggesting that LcFIN1 is directly regulated by LcCBF1. Taken together, our results suggest that LcFIN1 positively regulates plant adaptation response to cold stress and is a promising candidate gene to improve crop cold tolerance. PMID:26234381

  15. Evaluation of abiotic stresses of temperate estuaries by using resident zooplankton: A community vs. population approach

    NASA Astrophysics Data System (ADS)

    Paul, Sourav; Wooldridge, Tris; Perissinotto, Renzo

    2016-03-01

    By using permanently resident zooplankton, we assessed the ecological level (i.e. community and or population) that provides more in-depth indication of the stress related to salinity and temperature fluctuations in temperate estuaries. In the semi-arid warm temperate South Africa, the Gamtoos estuary experiences a full salinity gradient maintained by irregular but relatively frequent freshwater pulses, whereas the Kromme estuary is euhaline throughout its extent and receives only occasional freshwater inputs when the storage reservoir six km upstream overtops. Changes in the species evenness index of Pielou and the abundances of estuarine resident zooplankton species were modelled against salinity and temperature variations of respective estuaries. In the Gamtoos estuary, response of individual populations provided more in-depth information regarding zooplankton variability. However the most abundant resident zooplankton i.e. Acartia longipatella a copepod was not the best predictor of the salinity and temperature fluctuations. Conversely, the Kromme estuary study provided insights into the potential vulnerability of the resident estuarine zooplankton community to cold. Further, the population level study exposed responses of specific species against salinity changes. We discuss the pros and cons of designing ecological indicators of abiotic stress based on specific species, targeted to specific ecological level, and needs of considering the frequency and magnitude of fresh water inflow in an estuary. A suggestion is to use specific taxonomic group(s) (e.g. Copepods) to better understand the abiotic stress factors of specific set of estuaries (e.g. freshwater rich/starved) until a 'one size fits all' indicator is found for temperate estuaries.

  16. Salicylic acid-induced abiotic stress tolerance and underlying mechanisms in plants

    PubMed Central

    Khan, M. Iqbal R.; Fatma, Mehar; Per, Tasir S.; Anjum, Naser A.; Khan, Nafees A.

    2015-01-01

    Abiotic stresses (such as metals/metalloids, salinity, ozone, UV-B radiation, extreme temperatures, and drought) are among the most challenging threats to agricultural system and economic yield of crop plants. These stresses (in isolation and/or combination) induce numerous adverse effects in plants, impair biochemical/physiological and molecular processes, and eventually cause severe reductions in plant growth, development and overall productivity. Phytohormones have been recognized as a strong tool for sustainably alleviating adverse effects of abiotic stresses in crop plants. In particular, the significance of salicylic acid (SA) has been increasingly recognized in improved plant abiotic stress-tolerance via SA-mediated control of major plant-metabolic processes. However, the basic biochemical/physiological and molecular mechanisms that potentially underpin SA-induced plant-tolerance to major abiotic stresses remain least discussed. Based on recent reports, this paper: (a) overviews historical background and biosynthesis of SA under both optimal and stressful environments in plants; (b) critically appraises the role of SA in plants exposed to major abiotic stresses; (c) cross-talks potential mechanisms potentially governing SA-induced plant abiotic stress-tolerance; and finally (d) briefly highlights major aspects so far unexplored in the current context. PMID:26175738

  17. Distinguishing Biotic from Abiotic Phosphate Oxygen Isotopic Signatures

    NASA Astrophysics Data System (ADS)

    Blake, R.; Moyer, C.; Colman, A.; Liang, Y.; Dogru, D.

    2006-05-01

    On earth, phosphate has a strong biological oxygen isotope signature due to its concentration and intense cycling by living organisms as an essential nutrient. Phosphate does not undergo oxygen isotope exchange with water at low temperature without enzymatic catalysis, making the oxygen isotope ratio (18O/16O) of phosphate, δ18OP, an attractive biosignature in the search for early and extraterrestrial life. Recent laboratory and field studies have demonstrated that the δ18OP value of dissolved inorganic phosphate (PO4) records specific microbial activity and enzymatic reaction pathways in both laboratory cultures and natural waters/sediments (Blake et al., 2005; Colman et al 2005; Liang and Blake, 2005). Phosphate oxygen isotope biosignatures may be distinguished from abiotic signatures by: (1) evaluating the degree of temperature-dependent PO4-water oxygen isotope exchange in aqueous systems and deviation from equilibrium; and (2) evolution from an abiotic P reservoir signature towards a biotic P reservoir signature. Important abiotic processes potentially affecting phosphate δ18OP values include dissolution/precipitation, adsorption/desorption, recrystallization of PO4 mineral phases, diagenesis and metamorphism. For most of these processes, the recording, retention and alteration of δ18OP biosignatures have not been evaluated. Deep-sea hydrothermal vent fields are an ideal system in which to study the preservation and alteration of δ18OP biosignatures, as well as potential look-alikes produced by heat-promoted PO4 -water oxygen isotope exchange. Results from recent studies of δ18OP biosignatures in hydrothermal deposits near 9 and 21 degrees N. EPR and at Loihi seamount will be presented.

  18. Research advances in major cereal crops for adaptation to abiotic stresses.

    PubMed

    Maiti, R K; Satya, Pratik

    2014-01-01

    With devastating increase in population there is a great necessity to increase crop productivity of staple crops but the productivity is greatly affected by various abiotic stress factors such as drought, salinity. An attempt has been made a brief account on abiotic stress resistance of major cereal crops viz. In spite of good successes obtained on physiological and use molecular biology, the benefits of this high cost technology are beyond the reach of developing countries. This review discusses several morphological, anatomical, physiological, biochemical and molecular mechanisms of major cereal crops related to the adaptation of these crop to abiotic stress factors. It discusses the effect of abiotic stresses on physiological processes such as flowering, grain filling and maturation and plant metabolisms viz. photosynthesis, enzyme activity, mineral nutrition, and respiration. Though significant progress has been attained on the physiological, biochemical basis of resistance to abiotic stress factors, very little progress has been achieved to increase productivity under sustainable agriculture. Therefore, there is a great necessity of inter-disciplinary research to address this issue and to evolve efficient technology and its transfer to the farmers' fields. PMID:25523172

  19. Factors affecting rectal temperature measurement using commonly available digital thermometers.

    PubMed

    Naylor, Jonathan M; Streeter, Renee M; Torgerson, Paul

    2012-02-01

    Rectal temperature measurement is an essential part of physical examination of cattle and some physiological experiments. Modern digital thermometers are often used to measure rectal temperatures by students; this study describes their reliability and appropriate use. Students measured rectal temperature on 53 occasions using their personal digital thermometer and techniques gained from previous instruction, rectal temperature was also measured by an experienced person using a Cornell mercury thermometer completely inserted in the rectum. Cornell mercury thermometers values were 38.95±0.05°C (mean±1 SE, n=53). Student rectal temperature measurements using their initial technique were nearly 0.5°C lower, 38.46±0.07°C. After receiving instruction to insert the digital thermometer to the window, student obtained values were 38.77±0.06°C; these are significantly higher than with the student's initial technique and closer to those obtained with a Cornell thermometer. In a series of 53 water bath tests, student owned thermometers recorded similar mean values to those of a traceable (reference) digital thermometer, Cornell mercury thermometer readings were 0.2°C higher. 10 individual digital thermometers were repeatedly tested against a traceable thermometer in a water bath, one was inaccurate. In a separate experiment a trained clinician tested the effect of angle of insertion of a digital thermometer on temperature readings and the affect was <0.1°C. We conclude that accurate temperature measurements using digital thermometers are only likely if the thermometer is inserted to the beginning of the window and the thermometer's accuracy is checked periodically. PMID:21147490

  20. Abiotic stress modifies the synthesis of alpha-tocopherol and beta-carotene in phytoplankton species.

    PubMed

    Häubner, Norbert; Sylvander, Peter; Vuori, Kristiina; Snoeijs, Pauline

    2014-08-01

    We performed laboratory experiments to investi-gate whether the synthesis of the antioxidants α-tocopherol (vitamin E) and β-carotene in phytoplankton depends on changes in abiotic factors. Cultures of Nodularia spumigena, Phaeodactylum tricornutum, Skeletonema costatum, Dunaliella tertiolecta, Prorocentrum cordatum, and Rhodomonas salina were incubated at different tempe-ratures, photon flux densities and salinities for 48 h. We found that abiotic stress, within natural ecological ranges, affects the synthesis of the two antioxidants in different ways in different species. In most cases antioxidant production was stimulated by increased abiotic stress. In P. tricornutum KAC 37 and D. tertiolecta SCCAP K-0591, both good producers of this compound, α-tocopherol accumulation was negatively affected by environmentally induced higher photosystem II efficiency (Fv /Fm ). On the other hand, β-carotene accumulation was positively affected by higher Fv /Fm in N. spumigena KAC 7, P. tricornutum KAC 37, D. tertiolecta SCCAP K-0591 and R. salina SCCAP K-0294. These different patterns in the synthesis of the two compounds may be explained by their different locations and functions in the cell. While α-tocopherol is heavily involved in the protection of prevention of lipid peroxidation in membranes, β-carotene performs immediate photo-oxidative protection in the antennae complex of photosystem II. Overall, our results suggest a high variability in the antioxidant pool of natural aquatic ecosystems, which can be subject to short-term temperature, photon flux density and salinity fluctuations. The antioxidant levels in natural phytoplankton communities depend on species composition, the physiological condition of the species, and their respective strategies to deal with reactive oxygen species. Since α-tocopherol and β-carotene, as well as many other nonenzymatic antioxidants, are exclusively produced by photo-synthetic organisms, and are required by higher

  1. Basic factors controlling pest in high temperature systems

    NASA Technical Reports Server (NTRS)

    Berkowitz-Mattuck, J.; Rossetti, M.

    1971-01-01

    The catastrophic disintegration in air at intermediate temperatures of refractory materials which are very resistant to oxidation at high temperatures is known as pest. A study was undertaken to determine whether the mechanism proposed for pest failure in silicides might also be responsible for pest failure in NbAl3. The aim was to correlate oxidation kinetics in the range where disintegration of NbAl3 is observed with delayed failure data obtained under similar conditions. Studies were also undertaken to develop some understanding of deformation mechanisms in both silicides and aluminides.

  2. ABIOTIC ORGANIC REACTIONS AT MINERAL SURFACES

    EPA Science Inventory

    Abiotic organic reactions, such as hydrolysis, elimination, substitution, redox, and polymerization reactions, can be influenced by surfaces of clay and primary minerals, and of metal oxides. This influence is due to adsorption of the reactants to surface Lewis and Bronsted sites...

  3. Abiotic Bromination of Soil Organic Matter.

    PubMed

    Leri, Alessandra C; Ravel, Bruce

    2015-11-17

    Biogeochemical transformations of plant-derived soil organic matter (SOM) involve complex abiotic and microbially mediated reactions. One such reaction is halogenation, which occurs naturally in the soil environment and has been associated with enzymatic activity of decomposer organisms. Building on a recent finding that naturally produced organobromine is ubiquitous in SOM, we hypothesized that inorganic bromide could be subject to abiotic oxidations resulting in bromination of SOM. Through lab-based degradation treatments of plant material and soil humus, we have shown that abiotic bromination of particulate organic matter occurs in the presence of a range of inorganic oxidants, including hydrogen peroxide and assorted forms of ferric iron, producing both aliphatic and aromatic forms of organobromine. Bromination of oak and pine litter is limited primarily by bromide concentration. Fresh plant material is more susceptible to bromination than decayed litter and soil humus, due to a labile pool of mainly aliphatic compounds that break down during early stages of SOM formation. As the first evidence of abiotic bromination of particulate SOM, this study identifies a mechanistic source of the natural organobromine in humic substances and the soil organic horizon. Formation of organobromine through oxidative treatments of plant material also provides insights into the relative stability of aromatic and aliphatic components of SOM. PMID:26468620

  4. PHYSICOCHEMICAL FACTORS AFFECTING TOXICITY IN FRESHWATER: HARDNESS, PH, AND TEMPERATURE

    EPA Science Inventory

    A search of the literature for effects of hardness, pH, or temperature on the toxicity of chemicals to freshwater organisms suggested that the amount of reliable and useful data is limited. uch of the disparity among results reported in the literature was caused by improperly des...

  5. Factors determining the distribution and abundance of Dreissena polymorpha in lakes, dam reserviors and channels

    SciTech Connect

    Karatayev, A.

    1995-06-01

    This article addresses the several factors affecting the distribution and abundance of Dreissena polymorphia in bodies of water. Factors covered include: (1) salinity, (2) oxygen level, (3) temperature, (4) substrate, (5) depth, and (6) water chemistry. The analysis of the data allowed the specification of limiting or optimal concentrations of the principle abiotic parameters.

  6. Factors Controlling Elevated Temperature Strength Degradation of Silicon Carbide Composites

    NASA Technical Reports Server (NTRS)

    2005-01-01

    For 5 years, the cooperative agreement NCC3-763 has focused on the development and understanding of Sic-based composites. Most of the work was performed in the area of SiC fiber-reinforced composites for UEET and NGLT and in collaboration with Goodrich Corporation under a partially reimbursable Space Act Agreement. A smaller amount of work was performed on C fiber-reinforced SiC matrix composites for NGLT. Major accomplishments during this agreement included: Improvements to the interphase used in melt-infiltrated (MI) SiC/SiC composites which increases the life under stressed-oxidation at intermediate temperatures referred to as "outside-debonding". This concept is currently in the patent process and received a Space Act Award. Mechanistic-based models of intermediate temperature degradation for MI SiC/SiC Quantification and relatively robust relationships for matrix crack evolution under stress in SiC/SiC composites which serve as the basis for stress-strain and elevated temperature life models The furthering of acoustic emission as a useful tool in composite damage evolution and the extension of the technique to other composite systems Development of hybrid C-SiC fiber-reinforced SiC matrix composites Numerous presentations at conferences, industry partners, and government centers and publications in recognized proceedings and journals. Other recognition of the author's accomplishments by NASA with a TGIR award (2004), NASA's Medal for Public Service (2004), and The American Ceramic Society s Richard M. Fulrath Award (2005). The following will briefly describe the work of the past five years in the three areas of interest: SiC/SiC composite development, mechanistic understanding and modeling of SiC/SiC composites, and environmental durability of C/SiC composites. More detail can be found in the publications cited at the end of this report.

  7. Salicylic acid-induced abiotic stress tolerance and underlying mechanisms in plants.

    PubMed

    Khan, M Iqbal R; Fatma, Mehar; Per, Tasir S; Anjum, Naser A; Khan, Nafees A

    2015-01-01

    Abiotic stresses (such as metals/metalloids, salinity, ozone, UV-B radiation, extreme temperatures, and drought) are among the most challenging threats to agricultural system and economic yield of crop plants. These stresses (in isolation and/or combination) induce numerous adverse effects in plants, impair biochemical/physiological and molecular processes, and eventually cause severe reductions in plant growth, development and overall productivity. Phytohormones have been recognized as a strong tool for sustainably alleviating adverse effects of abiotic stresses in crop plants. In particular, the significance of salicylic acid (SA) has been increasingly recognized in improved plant abiotic stress-tolerance via SA-mediated control of major plant-metabolic processes. However, the basic biochemical/physiological and molecular mechanisms that potentially underpin SA-induced plant-tolerance to major abiotic stresses remain least discussed. Based on recent reports, this paper: (a) overviews historical background and biosynthesis of SA under both optimal and stressful environments in plants; (b) critically appraises the role of SA in plants exposed to major abiotic stresses; PMID:26175738

  8. Mantle hydrocarbons: Abiotic or biotic?

    SciTech Connect

    Sugisaki, Ryuichi; Mimura, Koichi

    1994-06-01

    Analyses of 227 rocks from fifty localities throughout the world showed that mantle derived rocks such as tectonized peridotites in ophiolite sequences (tectonites) and peridotite xenoliths in alkali basalts contain heavier hydrocarbons (n-alkanes), whereas igneous rocks produced by magmas such as gabbro and granite lack them. The occurrence of hydrocarbons indicates that they were not derived either from laboratory contamination or from field contamination; these compounds found in the mantle-derived rocks are called here {open_quotes}mantle hydrocarbons.{close_quotes} The existence of hydrocarbons correlates with petrogenesis. For example, peridotite cumulates produced by magmatic differentiation lack hydrocarbons whereas peridotite xenoliths derived from the mantle contain them. Gas chromatographic-mass spectrometric records of the mantle hydrocarbons resemble those of aliphatics in meteorites and in petroleum. Features of the hydrocarbons are that (a) the mantle hydrocarbons reside mainly along grain boundaries and in fluid inclusions of minerals; (b) heavier isoprenoids such as pristane and phytane are present; and (c) {delta}{sup 13}C of the mantle hydrocarbons is uniform (about {minus}27{per_thousand}). Possible origins for the mantle hydrocarbons are as follows. (1) They were inorganically synthesized by Fischer-Tropsch type reaction in the mantle. (2) They were delivered by meteorites and comets to the early Earth. (3) They were recycled by subduction. The mantle hydrocarbons in the cases of (1) and (2) are abiogenic and those in (3) are mainly biogenic. It appears that hydrocarbons may survive high pressures and temperatures in the mantle, but they are decomposed into lighter hydrocarbon gases such as CH{sub 4} at lower pressures when magmas intrude into the crust; consequently, peridotite cumulates do not contain heavier hydrocarbons but possess hydrocarbon gases up to C{sub 4}H{sub 10}. 76 refs., 5 figs., 3 tabs.

  9. Mantle hydrocarbons: abiotic or biotic?

    PubMed

    Sugisaki, R; Mimura, K

    1994-06-01

    Analyses of 227 rocks from fifty localities throughout the world showed that mantle derived rocks such as tectonized peridotites in ophiolite sequences (tectonites) arid peridotite xenoliths in alkali basalts contain heavier hydrocarbons (n-alkanes), whereas igneous rocks produced by magmas such as gabbro arid granite lack them. The occurrence of hydrocarbons indicates that they were not derived either from laboratory contamination or from held contamination; these compounds found in the mantle-derived rocks are called here "mantle hydrocarbons." The existence of hydrocarbons correlates with petrogenesis. For example, peridotite cumulates produced by magmatic differentiation lack hydrocarbons whereas peridotite xenoliths derived from the mantle contain them. Gas chromatographic-mass spectrometric records of the mantle hydrocarbons resemble those of aliphatics in meteorites and in petroleum. Features of the hydrocarbons are that (a) the mantle hydrocarbons reside mainly along grain boundaries and in fluid inclusions of minerals; (b) heavier isoprenoids such as pristane and phytane are present; and (c) delta 13C of the mantle hydrocarbons is uniform (about -27%). Possible origins for the mantle hydrocarbons are as follows. (1) They were in organically synthesized by Fischer-Tropsch type reaction in the mantle. (2) They were delivered by meteorites and comets to the early Earth. (3) They were recycled by subduction. The mantle hydrocarbons in the cases of (1) and (2) are abiogenic and those in (3) are mainly biogenic. It appears that hydrocarbons may survive high pressures and temperatures in the mantle, but they are decomposed into lighter hydrocarbon gases such as CH4 at lower pressures when magmas intrude into the crust; consequently, peridotite cumulates do not contain heavier hydrocarbons but possess hydrocarbon gases up to C4H10. PMID:11541663

  10. Mantle hydrocarbons: Abiotic or biotic?

    NASA Astrophysics Data System (ADS)

    Sugisaki, Ryuichi; Mimura, Koichi

    1994-06-01

    Analyses of 227 rocks from fifty localities throughout the world showed that mantle derived rocks such as tectonized peridotites in ophiolite sequences (tectonites) and peridotite xenoliths in alkali basalts contain heavier hydrocarbons ( n-alkanes), whereas igneous rocks produced by magmas such as gabbro and granite lack them. The occurrence of hydrocarbons indicates that they were not derived either from laboratory contamination or from field contamination; these compounds found in the mantle-derived rocks are called here "mantle hydrocarbons." The existence of hydrocarbons correlates with petrogenesis. For example, peridotite cumulates produced by magmatic differentiation lack hydrocarbons whereas peridotite xenoliths derived from the mantle contain them. Gas Chromatographic—mass spectrometric records of the mantle hydrocarbons resemble those of aliphatics in meteorites and in petroleum. Features of the hydrocarbons are that (a) the mantle hydrocarbons reside mainly along grain boundaries and in fluid inclusions of minerals (b) heavier isoprenoids such as pristane and phytane are present (c) δ13C of the mantle hydrocarbons is uniform (about -27%.). Possible origins for the mantle hydrocarbons are as follows. (1) They were inorganically synthesized by Fischer-Tropsch type reaction in the mantle. (2) They were delivered by meteorites and comets to the early Earth. (3) They were recycled by subduction. The mantle hydrocarbons in the cases of (1) and (2) are abiogenic and those in (3) are mainly biogenic. It appears that hydrocarbons may survive high pressures and temperatures in the mantle, but they are decomposed into lighter hydrocarbon gases such as CH 4 at lower pressures when magmas intrude into the crust; consequently, peridotite cumulates do not contain heavier hydrocarbons but possess hydrocarbon gases up to C 4H 10.

  11. Abiotic immobilization/detoxification of recalcitrant organics

    SciTech Connect

    Whelan, G. ); Sims, R.C. )

    1990-11-01

    In contrast to many remedial techniques that simply transfer hazardous wastes from one part of the environment to another (e.g., off-site landfilling), in situ restoration may offer a safe and cost-effective solution through transformation (to less hazardous products) or destruction of recalcitrant organics. Currently, the US Environmental Protection Agency and US Department of Energy are encouraging research that addresses the development of innovative alternatives for hazardous-waste control. One such alternative is biotic and abiotic immobilization and detoxification of polynuclear aromatic hydrocarbons (PNAs) as associated with the soil humification process. This paper discusses (1) the possibility of using abiotic catalysis (with manganese dioxide) to polymerize organic substances; (2) aspects associated with the thermodynamics and kinetics of the process, and (3) a simple model upon which analyses may be based. 36 refs., 7 figs., 3 tabs.

  12. Assessing Utilization and Environmental Risks of Important Genes in Plant Abiotic Stress Tolerance.

    PubMed

    Khan, Mohammad S; Khan, Muhammad A; Ahmad, Dawood

    2016-01-01

    Transgenic plants with improved salt and drought stress tolerance have been developed with a large number of abiotic stress-related genes. Among these, the most extensively used genes are the glycine betaine biosynthetic codA, the DREB transcription factors, and vacuolar membrane Na(+)/H(+) antiporters. The use of codA, DREBs, and Na(+)/H(+) antiporters in transgenic plants has conferred stress tolerance and improved plant phenotype. However, the future deployment and commercialization of these plants depend on their safety to the environment. Addressing environmental risk assessment is challenging since mechanisms governing abiotic stress tolerance are much more complex than that of insect resistance and herbicide tolerance traits, which have been considered to date. Therefore, questions arise, whether abiotic stress tolerance genes need additional considerations and new measurements in risk assessment and, whether these genes would have effects on weediness and invasiveness potential of transgenic plants? While considering these concerns, the environmental risk assessment of abiotic stress tolerance genes would need to focus on the magnitude of stress tolerance, plant phenotype and characteristics of the potential receiving environment. In the present review, we discuss environmental concerns and likelihood of concerns associated with the use of abiotic stress tolerance genes. Based on our analysis, we conclude that the uses of these genes in domesticated crop plants are safe for the environment. Risk assessment, however, should be carefully conducted on biofeedstocks and perennial plants taking into account plant phenotype and the potential receiving environment. PMID:27446095

  13. A NAP-Family Histone Chaperone Functions in Abiotic Stress Response and Adaptation.

    PubMed

    Tripathi, Amit K; Pareek, Ashwani; Singla-Pareek, Sneh Lata

    2016-08-01

    Modulation of gene expression is one of the most significant molecular mechanisms of abiotic stress response in plants. Via altering DNA accessibility, histone chaperones affect the transcriptional competence of genomic loci. However, in contrast to other factors affecting chromatin dynamics, the role of plant histone chaperones in abiotic stress response and adaptation remains elusive. Here, we studied the physiological function of a stress-responsive putative rice (Oryza sativa) histone chaperone of the NAP superfamily: OsNAPL6. We show that OsNAPL6 is a nuclear-localized H3/H4 histone chaperone capable of assembling a nucleosome-like structure. Utilizing overexpression and knockdown approaches, we found a positive correlation between OsNAPL6 expression levels and adaptation to multiple abiotic stresses. Results of comparative transcriptome profiling and promoter-recruitment studies indicate that OsNAPL6 functions during stress response via modulation of expression of various genes involved in diverse functions. For instance, we show that OsNAPL6 is recruited to OsRad51 promoter, activating its expression and leading to more efficient DNA repair and abrogation of programmed cell death under salinity and genotoxic stress conditions. These results suggest that the histone chaperone OsNAPL6 may serve a regulatory role in abiotic stress physiology possibly via modulating nucleosome dynamics at various stress-associated genomic loci. Taken together, our findings establish a hitherto unknown link between histone chaperones and abiotic stress response in plants. PMID:27342307

  14. A NAP-Family Histone Chaperone Functions in Abiotic Stress Response and Adaptation1[OPEN

    PubMed Central

    Pareek, Ashwani; Singla-Pareek, Sneh Lata

    2016-01-01

    Modulation of gene expression is one of the most significant molecular mechanisms of abiotic stress response in plants. Via altering DNA accessibility, histone chaperones affect the transcriptional competence of genomic loci. However, in contrast to other factors affecting chromatin dynamics, the role of plant histone chaperones in abiotic stress response and adaptation remains elusive. Here, we studied the physiological function of a stress-responsive putative rice (Oryza sativa) histone chaperone of the NAP superfamily: OsNAPL6. We show that OsNAPL6 is a nuclear-localized H3/H4 histone chaperone capable of assembling a nucleosome-like structure. Utilizing overexpression and knockdown approaches, we found a positive correlation between OsNAPL6 expression levels and adaptation to multiple abiotic stresses. Results of comparative transcriptome profiling and promoter-recruitment studies indicate that OsNAPL6 functions during stress response via modulation of expression of various genes involved in diverse functions. For instance, we show that OsNAPL6 is recruited to OsRad51 promoter, activating its expression and leading to more efficient DNA repair and abrogation of programmed cell death under salinity and genotoxic stress conditions. These results suggest that the histone chaperone OsNAPL6 may serve a regulatory role in abiotic stress physiology possibly via modulating nucleosome dynamics at various stress-associated genomic loci. Taken together, our findings establish a hitherto unknown link between histone chaperones and abiotic stress response in plants. PMID:27342307

  15. Assessing Utilization and Environmental Risks of Important Genes in Plant Abiotic Stress Tolerance

    PubMed Central

    Khan, Mohammad S.; Khan, Muhammad A.; Ahmad, Dawood

    2016-01-01

    Transgenic plants with improved salt and drought stress tolerance have been developed with a large number of abiotic stress-related genes. Among these, the most extensively used genes are the glycine betaine biosynthetic codA, the DREB transcription factors, and vacuolar membrane Na+/H+ antiporters. The use of codA, DREBs, and Na+/H+ antiporters in transgenic plants has conferred stress tolerance and improved plant phenotype. However, the future deployment and commercialization of these plants depend on their safety to the environment. Addressing environmental risk assessment is challenging since mechanisms governing abiotic stress tolerance are much more complex than that of insect resistance and herbicide tolerance traits, which have been considered to date. Therefore, questions arise, whether abiotic stress tolerance genes need additional considerations and new measurements in risk assessment and, whether these genes would have effects on weediness and invasiveness potential of transgenic plants? While considering these concerns, the environmental risk assessment of abiotic stress tolerance genes would need to focus on the magnitude of stress tolerance, plant phenotype and characteristics of the potential receiving environment. In the present review, we discuss environmental concerns and likelihood of concerns associated with the use of abiotic stress tolerance genes. Based on our analysis, we conclude that the uses of these genes in domesticated crop plants are safe for the environment. Risk assessment, however, should be carefully conducted on biofeedstocks and perennial plants taking into account plant phenotype and the potential receiving environment. PMID:27446095

  16. Hexagonal Lyotropic Liquid Crystal from Simple "Abiotic" Foldamers.

    PubMed

    Chen, Yu; Zhao, Zhiqiang; Bian, Zheng; Jin, Rizhe; Kang, Chuanqing; Qiu, Xuepeng; Guo, Haiquan; Du, Zhijun; Gao, Lianxun

    2016-08-01

    The motivation of foldamer chemistry is to identify novel building blocks that have the potential to imitate natural species. Peptides and peptide mimetics can form stable helical conformations and further self-assemble into diverse aggregates in water, where it is difficult to isolate a single helix. In contrast, most "abiotic" foldamers may fold into helical structures in solution, but are difficult to assemble into tertiary ones. It remains a challenge to obtain "abiotic" species similar to peptides. In this paper, a novel foldamer scaffold, in which p-phenyleneethynylene units are linked by chiral carbon atoms, was designed and prepared. In very dilute solutions, these oligomers were random coils. The hexamer and octamers could form a hexagonal lyotropic liquid crystal (LC) in CH2Cl2 when the concentrations reached the critical values. The microscopic observations indicated that they could assemble into the nanofibers in the LC. Interestingly, after some LC phases were diluted at room temperature, the nanofibers could be preserved. The good stabilities of the assemblies are possibly attributed to a more compact backbone and more rigid side chains. PMID:27547649

  17. Temperature factor for magnetic instability conditions of type - II superconductors

    NASA Astrophysics Data System (ADS)

    Romanovskii, V.

    2014-10-01

    The macroscopic development of interrelated electrodynamics and thermal states taking place both before and after instability onset in type-II superconductors are studied using the critical state and the flux creep concepts. The physical mechanisms of the non-isothermal formation of the critical state are discussed solving the set of unsteady thermo-electrodynamics equations taking into consideration the unknown moving penetration boundary of the magnetic flux. To make it, the numerical method, which allows to study diffusion phenomena with unknown moving phase-two boundary, is developed. The corresponding non-isothermal flux jump criteria are written. It is proved for the first time that, first, the diffusion phenomena in superconductors have the fission-chain-reaction nature, second, the stability conditions, losses in superconductor and its stable overheating before instability onset are mutually dependent. The results are compared with those following from the existing magnetic instability theory, which does not take into consideration the stable temperature increase of superconductor before the instability onset. It is shown that errors of isothermal approximation are significant for modes closed to adiabatic ones. Therefore, the well-known adiabatic flux jump criterion limits the range of possible stable superconducting states since a correct determination of their stability states must take into account the thermal prehistory of the stable magnetic flux penetration. As a result, the calculation errors in the isothermal approximation will rise when the sweep rate of an external magnetic field or the size of the superconductor’s cross-sectional area increase. The basic conclusions formulated in the framework of the critical state model are verified comparing the experimental results and the numerical analysis of the stability conditions and the temperature dynamics of the helicoid-type superconducting current-carrying element having real voltage

  18. Abiotic emissions of methane and reduced organic compounds from organic matter

    NASA Astrophysics Data System (ADS)

    Roeckmann, T.; Keppler, F.; Vigano, I.; Derendorp, L.; Holzinger, R.

    2012-12-01

    Recent laboratory studies show that the important greenhouse gas methane, but also other reduced atmospheric trace gases, can be emitted by abiotic processes from organic matter, such as plants, pure organic compounds and soils. It is very difficult to distinguish abiotic from biotic emissions in field studies, but in laboratory experiments this is easier because it is possible to carefully prepare/sterilize samples, or to control external parameters. For example, the abiotic emissions always show a strong increase with temperature when temperatures are increased to 70C or higher, well above the temperature optimum for bacterial activity. UV radiation has also been clearly shown to lead to emission of methane and other reduced gases from organic matter. Interesting information on the production mechanism has been obtained from isotope studies, both at natural abundance and with isotope labeling. For example, the methoxyl groups of pectin were clearly identified to produce methane. However, analysis of the isotopic composition of methane from natural samples clearly indicates that there must be other molecular mechanisms that lead to methane production. Abiotic methane generation could be a ubiquitous process that occurs naturally at low rates from many different sources.

  19. Abiotic Stresses Antagonize the Rice Defence Pathway through the Tyrosine-Dephosphorylation of OsMPK6

    PubMed Central

    Kishi-Kaboshi, Mitsuko; Matsushita, Akane; Jiang, Chang-Jie; Goto, Shingo; Takahashi, Akira; Hirochika, Hirohiko; Takatsuji, Hiroshi

    2015-01-01

    Plants, as sessile organisms, survive environmental changes by prioritizing their responses to the most life-threatening stress by allocating limited resources. Previous studies showed that pathogen resistance was suppressed under abiotic stresses. Here, we show the mechanism underlying this phenomenon. Phosphorylation of WRKY45, the central transcription factor in salicylic-acid (SA)-signalling-dependent pathogen defence in rice, via the OsMKK10-2–OsMPK6 cascade, was required to fully activate WRKY45. The activation of WRKY45 by benzothiadiazole (BTH) was reduced under low temperature and high salinity, probably through abscisic acid (ABA) signalling. An ABA treatment dephosphorylated/inactivated OsMPK6 via protein tyrosine phosphatases, OsPTP1/2, leading to the impaired activation of WRKY45 and a reduction in Magnaporthe oryzae resistance, even after BTH treatment. BTH induced a strong M. oryzae resistance in OsPTP1/2 knockdown rice, even under cold and high salinity, indicating that OsPTP1/2 is the node of SA-ABA signalling crosstalk and its down-regulation makes rice disease resistant, even under abiotic stresses. These results points to one of the directions to further improve crops by managing the tradeoffs between different stress responses of plants. PMID:26485146

  20. Temperature dependence of the electron Landé g-factor in cubic GaN

    NASA Astrophysics Data System (ADS)

    Buß, J. H.; Schupp, T.; As, D. J.; Hägele, D.; Rudolph, J.

    2015-12-01

    The temperature dependence of the electron Landé g-factor in bulk cubic GaN is investigated over an extremely broad temperature range from 15 K up to 500 K by time-resolved Kerr-rotation spectroscopy. The g-factor is found to be approximately constant over the full investigated temperature range. Calculations by k .p -theory predict a negligible temperature dependence g(T) in complete agreement with the experiment as a consequence of the large band-gap and small spin orbit splitting in cubic GaN.

  1. Low temperature coefficient of resistance and high gage factor in beryllium-doped silicon

    NASA Technical Reports Server (NTRS)

    Robertson, J. B.; Littlejohn, M. A.

    1974-01-01

    The gage factor and resistivity of p-type silicon doped with beryllium was studied as a function of temperature, crystal orientation, and beryllium doping concentration. It was shown that the temperature coefficient of resistance can be varied and reduced to zero near room temperature by varying the beryllium doping level. Similarly, the magnitude of the piezoresistance gage factor for beryllium-doped silicon is slightly larger than for silicon doped with a shallow acceptor impurity such as boron, whereas the temperature coefficient of piezoresistance is about the same for material containing these two dopants. These results are discussed in terms of a model for the piezoresistance of compensated p-type silicon.

  2. Abiotic transformation of dinitrophenols under sulfate-reducing conditions

    SciTech Connect

    Gui, L.; Bouwer, E.J.

    1996-10-01

    Dinitrophenols are hazardous chemicals commonly detected in the environment. Little is known about their fate under sulfate-reducing conditions (SRC) where H{sub 2}S level is elevated due to microbial activity. Dinitrophenols are susceptible to both biotic and abiotic transformation under SRC. The objectives of this research are to investigate dinitrophenol transformation using hydrogen sulfide as a reductant, and to determine factors that affect the abiotic transformation kinetics under SRC. Dinitrophenols studied were 2,4-dinitrophenol (DNP), 4,6-dinitro-o-cresol (DNOC), and 2-sec-butyl-4,6-dinitrophenol (dinoseb). All three dinitrophenols were transformed through an ortho-nitroreduction pathway. In the presence of H{sub 2}S as the bulk reductant and a small amount of trace metals (10{sup -6} to 10{sup -7} M), pseudo-first-order kinetics was observed. Addition of yeast extract (YE, 0.02%) enhanced dinoseb transformation rate significantly. An increase in HS concentration resulted in Michaelis-Menton type kinetics for dinoseb in the presence of trace metals and YE, suggesting that trace metals and YE functioned as electron mediators.

  3. Leaf ontogeny strongly influences photosynthetic tolerance to drought and high temperature in Gossypium hirsutum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Temperature and drought are major abiotic limitations to crop productivity worldwide. While abiotic stress physiology research has focused primarily on fully expanded leaves, no studies have investigated photosynthetic tolerance to concurrent drought and high temperature during leaf ontogeny. To add...

  4. Identification of Arabidopsis Candidate Genes in Response to Biotic and Abiotic Stresses Using Comparative Microarrays

    PubMed Central

    Sham, Arjun; Moustafa, Khaled; Al-Ameri, Salma; Al-Azzawi, Ahmed; Iratni, Rabah; AbuQamar, Synan

    2015-01-01

    Plants have evolved with intricate mechanisms to cope with multiple environmental stresses. To adapt with biotic and abiotic stresses, plant responses involve changes at the cellular and molecular levels. The current study was designed to investigate the effects of combinations of different environmental stresses on the transcriptome level of Arabidopsis genome using public microarray databases. We investigated the role of cyclopentenones in mediating plant responses to environmental stress through TGA (TGACG motif-binding factor) transcription factor, independently from jasmonic acid. Candidate genes were identified by comparing plants inoculated with Botrytis cinerea or treated with heat, salt or osmotic stress with non-inoculated or non-treated tissues. About 2.5% heat-, 19% salinity- and 41% osmotic stress-induced genes were commonly upregulated by B. cinerea-treatment; and 7.6%, 19% and 48% of genes were commonly downregulated by B. cinerea-treatment, respectively. Our results indicate that plant responses to biotic and abiotic stresses are mediated by several common regulatory genes. Comparisons between transcriptome data from Arabidopsis stressed-plants support our hypothesis that some molecular and biological processes involved in biotic and abiotic stress response are conserved. Thirteen of the common regulated genes to abiotic and biotic stresses were studied in detail to determine their role in plant resistance to B. cinerea. Moreover, a T-DNA insertion mutant of the Responsive to Dehydration gene (rd20), encoding for a member of the caleosin (lipid surface protein) family, showed an enhanced sensitivity to B. cinerea infection and drought. Overall, the overlapping of plant responses to abiotic and biotic stresses, coupled with the sensitivity of the rd20 mutant, may provide new interesting programs for increased plant resistance to multiple environmental stresses, and ultimately increases its chances to survive. Future research directions towards a

  5. Identification of Arabidopsis candidate genes in response to biotic and abiotic stresses using comparative microarrays.

    PubMed

    Sham, Arjun; Moustafa, Khaled; Al-Ameri, Salma; Al-Azzawi, Ahmed; Iratni, Rabah; AbuQamar, Synan

    2015-01-01

    Plants have evolved with intricate mechanisms to cope with multiple environmental stresses. To adapt with biotic and abiotic stresses, plant responses involve changes at the cellular and molecular levels. The current study was designed to investigate the effects of combinations of different environmental stresses on the transcriptome level of Arabidopsis genome using public microarray databases. We investigated the role of cyclopentenones in mediating plant responses to environmental stress through TGA (TGACG motif-binding factor) transcription factor, independently from jasmonic acid. Candidate genes were identified by comparing plants inoculated with Botrytis cinerea or treated with heat, salt or osmotic stress with non-inoculated or non-treated tissues. About 2.5% heat-, 19% salinity- and 41% osmotic stress-induced genes were commonly upregulated by B. cinerea-treatment; and 7.6%, 19% and 48% of genes were commonly downregulated by B. cinerea-treatment, respectively. Our results indicate that plant responses to biotic and abiotic stresses are mediated by several common regulatory genes. Comparisons between transcriptome data from Arabidopsis stressed-plants support our hypothesis that some molecular and biological processes involved in biotic and abiotic stress response are conserved. Thirteen of the common regulated genes to abiotic and biotic stresses were studied in detail to determine their role in plant resistance to B. cinerea. Moreover, a T-DNA insertion mutant of the Responsive to Dehydration gene (rd20), encoding for a member of the caleosin (lipid surface protein) family, showed an enhanced sensitivity to B. cinerea infection and drought. Overall, the overlapping of plant responses to abiotic and biotic stresses, coupled with the sensitivity of the rd20 mutant, may provide new interesting programs for increased plant resistance to multiple environmental stresses, and ultimately increases its chances to survive. Future research directions towards a

  6. Abiotic CO2 reduction during geologic carbon sequestration facilitated by Fe(II)-bearing minerals

    NASA Astrophysics Data System (ADS)

    Nielsen, L. C.; Maher, K.; Bird, D. K.; Brown, G. E.; Thomas, B.; Johnson, N. C.; Rosenbauer, R. J.

    2012-12-01

    Redox reactions involving subsurface minerals and fluids and can lead to the abiotic generation of hydrocarbons from CO2 under certain conditions. Depleted oil reservoirs and saline aquifers targeted for geologic carbon sequestration (GCS) can contain significant quantities of minerals such as ferrous chlorite, which could facilitate the abiotic reduction of carbon dioxide to n-carboxylic acids, hydrocarbons, and amorphous carbon (C0). If such reactions occur, the injection of supercritical CO2 (scCO2) could significantly alter the oxidation state of the reservoir and cause extensive reorganization of the stable mineral assemblage via dissolution and reprecipitation reactions. Naturally occurring iron oxide minerals such as magnetite are known to catalyze CO2 reduction, resulting in the synthesis of organic compounds. Magnetite is thermodynamically stable in Fe(II) chlorite-bearing mineral assemblages typical of some reservoir formations. Thermodynamic calculations demonstrate that GCS reservoirs buffered by the chlorite-kaolinite-carbonate(siderite/magnesite)-quartz assemblage favor the reduction of CO2 to n-carboxylic acids, hydrocarbons, and C0, although the extent of abiotic CO2 reduction may be kinetically limited. To investigate the rates of abiotic CO2 reduction in the presence of magnetite, we performed batch abiotic CO2 reduction experiments using a Dickson-type rocking hydrothermal apparatus at temperatures (373 K) and pressures (100 bar) within the range of conditions relevant to GCS. Blank experiments containing CO2 and H2 were used to rule out the possibility of catalytic activity of the experimental apparatus. Reaction of brine-suspended magnetite nanoparticles with scCO2 at H2 partial pressures typical of reservoir rocks - up to 100 and 0.1 bars respectively - was used to investigate the kinetics of magnetite-catalyzed abiotic CO2 reduction. Later experiments introducing ferrous chlorite (ripidolite) were carried out to determine the potential for

  7. Attachment of Escherichia coli O157:H7 to abiotic surfaces of cooking utensils.

    PubMed

    Tsuji, Makiko; Yokoigawa, Kumio

    2012-04-01

    We examined the attachment of enterohemorrhagic Escherichia coli O157:H7 to abiotic surfaces of cooking utensils. When the cell suspension in 0.85% NaCl (about 100 cells/mL, 10 mL) was contacted with various abiotic surfaces (square pieces, 25 cm²) at 25 °C for 20 min, the number of attached cells varied depending on the types of abiotic materials. The pathogen well attached to stainless steel (about 50 cells/25 cm²), pure titanium (35 to 45 cells/25 cm²), and glass (about 20 cells/25 cm²), but little attached to aluminum foil and plastics, irrespective of strains used. Fewer cells (below 10 cells/25 cm²) attached to stainless steel, pure titanium, and glass surfaces conditioned with aseptically sliced beef (sirloin) and autoclaved beef tallow at 25 °C for 20 min, but bovine serum albumin did not reduce the number of attached cells. The cells grown at 15 °C to the stationary phase (OD660 = about 2.8) less attached to the abiotic surfaces than those grown at 25 °C and 37 °C. When we pretreated the cells at 37 °C for 2 h with 50 μM N-hexanoyl-L-homoserine lactone (HHL), the number of cells attached to stainless steel was reduced by 70%. The number of cells attached to cooking utensils seemed to change depending on types of abiotic materials, adhesion of beef tallow to abiotic surfaces, growth temperature of the pathogen, and HHL-producing bacteria. PMID:22515247

  8. Abiotic synthesis of acylglycerols under simulated hydrothermal conditions and micelle formation

    NASA Astrophysics Data System (ADS)

    Simoneit, B.; Rushdi, A.; Deamer, D.

    Abiotic formation of aliphatic lipid compounds i e fatty acids alcohols and acylglycerols has been reported to occur at elevated temperatures and pressures under simulated hydrothermal conditions McCollom et al 1999 Rushdi and Simoneit 2001 2006 Although abiotic chemistry may occur at these conditions the prebiotic self-assembly of micelles to bilayer to vesicles protocells may have occurred elsewhere Amphipathic compounds such as fatty acids and acylglycerols are important candidates for micelle bilayer vesicle formation Thus it is of interest to demonstrate that abiotic lipids amphiphiles precursor compounds for abiotic cellular membranes Deamer 1997 can be synthesized under hydrothermal conditions Hydrothermal experiments were conducted to study condensation reactions of model lipid precursors in aqueous media to form acylglycerols glyceryl alkanoates at elevated temperatures under confining pressures Stainless steel vessels 316SS Sno-Trik high pressure couplings with internal capacities of 286 underline 2 mu l were used for the condensation reactions using a mixture of 0 14 mM glycerol and 0 35 mM of n-alkanoic acid Nine different alkanoic acids ranging from C 7 to C 16 except C 8 were used in these experiments The condensation products were two isomers each of monoacylglycerols and diacylglycerols as well as the corresponding triacylglycerol The product yields were 13-28 for monoacylglycerols 6-13 for diacylglycerols and 1-4 for triacylglycerols The results indicated that 1

  9. Regulatory roles of serotonin and melatonin in abiotic stress tolerance in plants.

    PubMed

    Kaur, Harmeet; Mukherjee, Soumya; Baluska, Frantisek; Bhatla, Satish C

    2015-01-01

    Understanding the physiological and biochemical basis of abiotic stress tolerance in plants has always been one of the major aspects of research aiming to enhance plant productivity in arid and semi-arid cultivated lands all over the world. Growth of stress-tolerant transgenic crops and associated agricultural benefits through increased productivity, and related ethical issues, are also the major concerns of current research in various laboratories. Interesting data on the regulation of abiotic stress tolerance in plants by serotonin and melatonin has accumulated in the recent past. These two indoleamines possess antioxidative and growth-inducing properties, thus proving beneficial for stress acclimatization. Present review shall focus on the modes of serotonin and melatonin-induced regulation of abiotic stress tolerance in plants. Complex molecular interactions of serotonin and auxin-responsive genes have suggested their antagonistic nature. Data from genomic and metabolomic analyses of melatonin-induced abiotic stress signaling have lead to an understanding of the regulation of stress tolerance through the modulation of transcription factors, enzymes and various signaling molecules. Melatonin, nitric oxide (NO) and calmodulin interactions have provided new avenues for research on the molecular aspects of stress physiology in plants. Investigations on the characterization of receptors associated with serotonin and melatonin responses, are yet to be undertaken in plants. Patenting of biotechnological inventions pertaining to serotonin and melatonin formulations (through soil application or foliar spray) are expected to be some of the possible ways to regulate abiotic stress tolerance in plants. The present review, thus, summarizes the regulatory roles of serotonin and melatonin in modulating the signaling events accompanying abiotic stress in plants. PMID:26633566

  10. Regulatory roles of serotonin and melatonin in abiotic stress tolerance in plants

    PubMed Central

    Kaur, Harmeet; Mukherjee, Soumya; Baluska, Frantisek; Bhatla, Satish C

    2015-01-01

    Understanding the physiological and biochemical basis of abiotic stress tolerance in plants has always been one of the major aspects of research aiming to enhance plant productivity in arid and semi-arid cultivated lands all over the world. Growth of stress-tolerant transgenic crops and associated agricultural benefits through increased productivity, and related ethical issues, are also the major concerns of current research in various laboratories. Interesting data on the regulation of abiotic stress tolerance in plants by serotonin and melatonin has accumulated in the recent past. These two indoleamines possess antioxidative and growth-inducing properties, thus proving beneficial for stress acclimatization. Present review shall focus on the modes of serotonin and melatonin-induced regulation of abiotic stress tolerance in plants. Complex molecular interactions of serotonin and auxin-responsive genes have suggested their antagonistic nature. Data from genomic and metabolomic analyses of melatonin-induced abiotic stress signaling have lead to an understanding of the regulation of stress tolerance through the modulation of transcription factors, enzymes and various signaling molecules. Melatonin, nitric oxide (NO) and calmodulin interactions have provided new avenues for research on the molecular aspects of stress physiology in plants. Investigations on the characterization of receptors associated with serotonin and melatonin responses, are yet to be undertaken in plants. Patenting of biotechnological inventions pertaining to serotonin and melatonin formulations (through soil application or foliar spray) are expected to be some of the possible ways to regulate abiotic stress tolerance in plants. The present review, thus, summarizes the regulatory roles of serotonin and melatonin in modulating the signaling events accompanying abiotic stress in plants. PMID:26633566

  11. Temperature dependence of Debye-Waller factor in dye-doped polymers

    NASA Astrophysics Data System (ADS)

    Saikan, S.; Imaoka, A.; Kanematsu, Y.; Sakoda, K.; Kominami, K.; Iwamoto, M.

    1990-02-01

    The temperature dependence of the Debye-Waller factor in dye-doped polymers has been investigated with femtosecond accumulated photon echo. The superiority of polyvinyl alcohol as the host polymer for the optical-memory material is ascribed to the higher phonon sideband frequency in this sample. It is pointed out that the temperature dependence of the Debye-Waller factor, in particular the phonon sideband frequency, is of fundamental importance to finding out the best polymer for high-temperature optical memory based on photochemical hole burning.

  12. Temporal dynamics of biotic and abiotic drivers of litter decomposition.

    PubMed

    García-Palacios, Pablo; Shaw, E Ashley; Wall, Diana H; Hättenschwiler, Stephan

    2016-05-01

    Climate, litter quality and decomposers drive litter decomposition. However, little is known about whether their relative contribution changes at different decomposition stages. To fill this gap, we evaluated the relative importance of leaf litter polyphenols, decomposer communities and soil moisture for litter C and N loss at different stages throughout the decomposition process. Although both microbial and nematode communities regulated litter C and N loss in the early decomposition stages, soil moisture and legacy effects of initial differences in litter quality played a major role in the late stages of the process. Our results provide strong evidence for substantial shifts in how biotic and abiotic factors control litter C and N dynamics during decomposition. Taking into account such temporal dynamics will increase the predictive power of decomposition models that are currently limited by a single-pool approach applying control variables uniformly to the entire decay process. PMID:26947573

  13. WRKY Proteins: Signaling and Regulation of Expression during Abiotic Stress Responses

    PubMed Central

    Banerjee, Aditya

    2015-01-01

    WRKY proteins are emerging players in plant signaling and have been thoroughly reported to play important roles in plants under biotic stress like pathogen attack. However, recent advances in this field do reveal the enormous significance of these proteins in eliciting responses induced by abiotic stresses. WRKY proteins act as major transcription factors, either as positive or negative regulators. Specific WRKY factors which help in the expression of a cluster of stress-responsive genes are being targeted and genetically modified to induce improved abiotic stress tolerance in plants. The knowledge regarding the signaling cascade leading to the activation of the WRKY proteins, their interaction with other proteins of the signaling pathway, and the downstream genes activated by them are altogether vital for justified targeting of the WRKY genes. WRKY proteins have also been considered to generate tolerance against multiple abiotic stresses with possible roles in mediating a cross talk between abiotic and biotic stress responses. In this review, we have reckoned the diverse signaling pattern and biological functions of WRKY proteins throughout the plant kingdom along with the growing prospects in this field of research. PMID:25879071

  14. Overexpression of wheat ubiquitin gene, Ta-Ub2, improves abiotic stress tolerance of Brachypodium distachyon.

    PubMed

    Kang, Hanhan; Zhang, Meng; Zhou, Shumei; Guo, Qifang; Chen, Fengjuan; Wu, Jiajie; Wang, Wei

    2016-07-01

    Ubiquitination plays an important role in regulating plant's development and adaptability to abiotic stress. To investigate the possible functions of a wheat monoubiquitin gene Ta-Ub2 in abiotic stress in monocot and compare it with that in dicot, we generated transgenic Brachypodium plants overexpressing Ta-Ub2 under the control of CaMV35s and stress-inducible RD29A promoters. The constitutive expression of Ta-Ub2 displayed slight growth inhibition in the growth of transgenic Brachypodium distachyon under the control conditions. However, this inhibition was minimized by expression of Ta-Ub2 under the control of stress-inducible RD29A promoter. Compared with WT, the transgenic plants preserved more water and showed higher enzymatic antioxidants under drought stress, which might be related to the change in the expression of some antioxidant genes. The expression of C-repeat binding factors transcription factor genes in the transgenic B. distachyon lines were upregulated under water stress. Salt and cold tolerances of transgenic B. distachyon were also improved. Although the phenotypic changes in the transgenic plants were different, overexpression of Ta-Ub2 improved the abiotic stress tolerance in both dicot and monocot plants. The improvement in Ta-Ub2 transgenic plants in abiotic stress tolerance might be, at least partly, through regulating the gene expression and increasing the enzymatic antioxidants. PMID:27181952

  15. Electrode impedance analysis of chronic tungsten microwire neural implants: understanding abiotic vs. biotic contributions.

    PubMed

    Sankar, Viswanath; Patrick, Erin; Dieme, Robert; Sanchez, Justin C; Prasad, Abhishek; Nishida, Toshikazu

    2014-01-01

    Changes in biotic and abiotic factors can be reflected in the complex impedance spectrum of the microelectrodes chronically implanted into the neural tissue. The recording surface of the tungsten electrode in vivo undergoes abiotic changes due to recording site corrosion and insulation delamination as well as biotic changes due to tissue encapsulation as a result of the foreign body immune response. We reported earlier that large changes in electrode impedance measured at 1 kHz were correlated with poor electrode functional performance, quantified through electrophysiological recordings during the chronic lifetime of the electrode. There is a need to identity the factors that contribute to the chronic impedance variation. In this work, we use numerical simulation and regression to equivalent circuit models to evaluate both the abiotic and biotic contributions to the impedance response over chronic implant duration. COMSOL® simulation of abiotic electrode morphology changes provide a possible explanation for the decrease in the electrode impedance at long implant duration while biotic changes play an important role in the large increase in impedance observed initially. PMID:24847248

  16. Electrode impedance analysis of chronic tungsten microwire neural implants: understanding abiotic vs. biotic contributions

    PubMed Central

    Sankar, Viswanath; Patrick, Erin; Dieme, Robert; Sanchez, Justin C.; Prasad, Abhishek; Nishida, Toshikazu

    2014-01-01

    Changes in biotic and abiotic factors can be reflected in the complex impedance spectrum of the microelectrodes chronically implanted into the neural tissue. The recording surface of the tungsten electrode in vivo undergoes abiotic changes due to recording site corrosion and insulation delamination as well as biotic changes due to tissue encapsulation as a result of the foreign body immune response. We reported earlier that large changes in electrode impedance measured at 1 kHz were correlated with poor electrode functional performance, quantified through electrophysiological recordings during the chronic lifetime of the electrode. There is a need to identity the factors that contribute to the chronic impedance variation. In this work, we use numerical simulation and regression to equivalent circuit models to evaluate both the abiotic and biotic contributions to the impedance response over chronic implant duration. COMSOL® simulation of abiotic electrode morphology changes provide a possible explanation for the decrease in the electrode impedance at long implant duration while biotic changes play an important role in the large increase in impedance observed initially. PMID:24847248

  17. The Effect of Temperature Dependent Frequency Factor on the Evaluated Trapping Parameters of TSL Glow Curves

    NASA Astrophysics Data System (ADS)

    Yazici, A. N.; Öztürk, Z.

    1998-01-01

    The effect of temperature dependency on frequency factor and its relationship to trapping parameters is discussed by using the peak shape method. The coefficients appearing in the peak shape formula for the calculation of the activation energy have been determined and tabulated for the symmetry factor mg(X) for x=0.50 and 0.75 of the peak intensity. It is found that significant errors occur in the value of the trapping parameters if the temperature dependecy of the frequency factor is not consider.

  18. Nitrogen isotopic fractionation during abiotic synthesis of organic solid particles

    NASA Astrophysics Data System (ADS)

    Kuga, Maïa; Carrasco, Nathalie; Marty, Bernard; Marrocchi, Yves; Bernard, Sylvain; Rigaudier, Thomas; Fleury, Benjamin; Tissandier, Laurent

    2014-05-01

    The formation of organic compounds is generally assumed to result from abiotic processes in the Solar System, with the exception of biogenic organics on Earth. Nitrogen-bearing organics are of particular interest, notably for prebiotic perspectives but also for overall comprehension of organic formation in the young Solar System and in planetary atmospheres. We have investigated abiotic synthesis of organics upon plasma discharge, with special attention to N isotope fractionation. Organic aerosols were synthesized from N2-CH4 and N2-CO gaseous mixtures using low-pressure plasma discharge experiments, aimed at simulating chemistry occurring in Titan's atmosphere and in the protosolar nebula, respectively. The nitrogen content, the N speciation and the N isotopic composition were analyzed in the resulting organic aerosols. Nitrogen is efficiently incorporated into the synthesized solids, independently of the oxidation degree, of the N2 content of the starting gas mixture, and of the nitrogen speciation in the aerosols. The aerosols are depleted in 15N by 15-25‰ relative to the initial N2 gas, whatever the experimental setup is. Such an isotopic fractionation is attributed to mass-dependent kinetic effect(s). Nitrogen isotope fractionation upon electric discharge cannot account for the large N isotope variations observed among Solar System objects and reservoirs. Extreme N isotope signatures in the Solar System are more likely the result of self-shielding during N2 photodissociation, exotic effect during photodissociation of N2 and/or low temperature ion-molecule isotope exchange. Kinetic N isotope fractionation may play a significant role in the Titan's atmosphere. On the Titan's night side, 15N-depletion resulting from electron driven reactions may counterbalance photo-induced 15N enrichments occurring on the day's side. We also suggest that the low δ15N values of Archaean organic matter (Beaumont and Robert, 1999) are partly the result of abiotic synthesis of

  19. Unveiling the Redox Control of Plant Reproductive Development during Abiotic Stress

    PubMed Central

    Zinta, Gaurav; Khan, Asif; AbdElgawad, Hamada; Verma, Vipasha; Srivastava, Ashish Kumar

    2016-01-01

    Plants being sessile in nature are often challenged to various abiotic stresses including temperature fluctuations, water supply, salinity, and nutrient availability. Exposure of plants to such environmental perturbations result in the formation of reactive oxygen species (ROS) in cells. To scavenge ROS, enzymatic and molecular antioxidants are produced at a cellular level. ROS act as a signaling entity at lower concentrations maintaining normal growth and development, but if their levels increase beyond certain threshold, they produce toxic effects in plants. Some developmental stages, such as development of reproductive organs are more sensitive to abiotic stress than other stages of growth. As success of plant reproductive development is directly correlated with grain yield, stresses coinciding with reproductive phase results in the higher yield losses. In this article, we summarize the redox control of plant reproductive development, and elaborate how redox homeostasis is compromised during abiotic stress exposure. We highlight why more emphasis should be given to understand redox control of plant reproductive organ development during abiotic stress exposure96to engineer crops with better crop yield. We specifically discuss the role of ROS as a signaling molecule and its cross-talk with other signaling molecules such as hormones and sugars. PMID:27379102

  20. Unveiling the Redox Control of Plant Reproductive Development during Abiotic Stress.

    PubMed

    Zinta, Gaurav; Khan, Asif; AbdElgawad, Hamada; Verma, Vipasha; Srivastava, Ashish Kumar

    2016-01-01

    Plants being sessile in nature are often challenged to various abiotic stresses including temperature fluctuations, water supply, salinity, and nutrient availability. Exposure of plants to such environmental perturbations result in the formation of reactive oxygen species (ROS) in cells. To scavenge ROS, enzymatic and molecular antioxidants are produced at a cellular level. ROS act as a signaling entity at lower concentrations maintaining normal growth and development, but if their levels increase beyond certain threshold, they produce toxic effects in plants. Some developmental stages, such as development of reproductive organs are more sensitive to abiotic stress than other stages of growth. As success of plant reproductive development is directly correlated with grain yield, stresses coinciding with reproductive phase results in the higher yield losses. In this article, we summarize the redox control of plant reproductive development, and elaborate how redox homeostasis is compromised during abiotic stress exposure. We highlight why more emphasis should be given to understand redox control of plant reproductive organ development during abiotic stress exposure96to engineer crops with better crop yield. We specifically discuss the role of ROS as a signaling molecule and its cross-talk with other signaling molecules such as hormones and sugars. PMID:27379102

  1. Study of temperature factors in cubic crystals by high-voltage electron diffraction.

    PubMed

    Matsumura, S; Tomokiyo, Y; Oki, K

    1989-07-01

    The critical voltages for systematic reflections and splits of Kikuchi lines were measured using a high-voltage electron microscope to investigate the atomic temperature factors in cubic crystals. The split of the Kikuchi line at the intersection with the forbidden 222 Kikuchi line as well as the critical voltage of the 333 reflection for Si and Ge decreased steeply with temperature. The temperature dependence showed that the anharmonic contribution to the atomic-temperature factor for Si and Ge is extremely weak in the temperature range 300 approximately 1078 K. On the contrary, the B factors obtained from the measured critical voltages for Al, Cu, and Fe varied nonlinearly with temperature, suggesting the importance of the anharmonic effect in the vibration of atoms. The observed temperature dependence of the critical voltages for the metals were compared with calculations based on harmonic, quasi-harmonic, and anharmonic approximations. The quasi-harmonic approximation that takes into account the thermal expansion modification reproduces well the observed values for Fe but not those for Al and Cu. The effect of intrinsic anharmonic vibration should be considered for reproducing the results for Al and Cu. Fitting the measured critical voltages with the calculated ones, we estimated the values for coefficients of the isolated atom potentials. The results are in good agreement with those obtained by neutron and X-ray diffraction. PMID:2795232

  2. Influence of environmental factors on infrared eye temperature measurements in cattle.

    PubMed

    Church, J S; Hegadoren, P R; Paetkau, M J; Miller, C C; Regev-Shoshani, G; Schaefer, A L; Schwartzkopf-Genswein, K S

    2014-02-01

    Environmental factors were evaluated to determine potential limitations in using cattle eye temperatures obtained through infrared thermography (IRT) for early disease detection systems or in animal welfare research studies. The effects of the following factors on IRT eye temperatures in cattle and a fabricated surrogate "eye" were evaluated: camera to object distance, wind speed, camera settings (distance, emissivity, and humidity), and solar loading. Wind speed in both live animals and using a surrogate "eye" was found to decrease the IRT temperature. In the presence of ∼ 7 km/h wind, the mean IRT eye temperature decreased by 0.43 ± 0.13 °C and; at higher wind speeds (∼ 12 km/h), the temperature decreased by 0.78 ± 0.33 °C. Direct sunlight was found to increase the IRT eye temperature by 0.56 ± 0.36 °C. It was determined that environmental factors impact IRT temperature measurements significantly and therefore must be managed to ensure reproducible and accurate readings. PMID:24290729

  3. Oxidation of Black Carbon by Biotic and Abiotic Processes

    SciTech Connect

    Cheng, Chih-hsin; Lehmann, Johannes C.; Thies, Janice E.; Burton, Sarah D.; Engelhard, Mark H.

    2006-11-01

    The objectives of this study were to quantify the relative importance of either biotic or abiotic oxidation of biomass-derived black carbon (BC) and to characterize the surface properties and charge characteristics of oxidized particulate BC. We incubated BC and BC-soil mixtures at two different temperatures (30 C and 70 C) with and without microbial inoculation, nutrient additions, or manure amendments for four months. Abiotic processes were more important for oxidation of BC than biotic processes during this short-term incubation, as inoculation with microorganisms did not change any of the measured parameters. Black C incubated at both 30 C and 70 C without microbial activity showed dramatic decreases in pH (in water) from 5.4 to 5.2 and 3.4, as well as increases in cation exchange capacity (CEC at pH 7) by 53% and 538% and in oxygen (O) contents by 4% and 38%, respectively. Boehm titration and Fourier transform infrared (FTIR) spectroscopy suggested that the formation of carboxylic functional groups was the reason for the enhanced CEC during oxidation. The analyses of BC surface properties by X-ray photoelectron spectroscopy (XPS) indicated that the oxidation of BC particles initiated on the surface. Incubation at 30 C only enhanced oxidation on particle surfaces, while oxidation during incubation at 70 C penetrated into the interior of particles. Such short-term oxidation of BC has great significance for the stability of BC in soils as well as for its effects on soil fertility and biogeochemistry.

  4. Formation of Intermediate Carbon Phases in Hydrothermal Abiotic Organic Synthesis

    NASA Astrophysics Data System (ADS)

    Fu, Q.; Foustoukos, D. I.; Seyfried, W. E.

    2005-12-01

    With high dissolved concentrations of methane and other hydrocarbon species revealed at the Rainbow and Logatchev vent systems on the Mid-Atlantic Ridge, it is essential to better understand reaction pathways of abiotic organic synthesis in hydrothermal systems. Thus, we performed a hydrothermal carbon reduction experiment with 13C labeled carbon source at temperature and pressure conditions that approximate those inferred for ultramafic-hosted hydrothermal systems. Pentlandite, a common alteration mineral phase in subseafloor reaction zones, acted as a potential catalyst. Surface analysis techniques (XPS and ToF-SIMS) were used to characterize intermediate carbon species within this process. Time series dissolved H2 and H2S concentrations indicated thermodynamic equilibrium. Dissolved H2 and H2S concentrations of 13 and 2 mmol/kg, respectively, are approximately equivalent to measured values in Rainbow and Logatchev hydrothermal systems. Isotopically pure 13C methane and other alkane species (C2H6 and C3H8) were observed throughout the experiment, and attained steady state conditions. XPS analysis on mineral product surface indicated carbon enrichment on mineral surface following reaction. The majority of surface carbon involves species containing C-C or C-H bonds, such as alkyl or methylene groups. Alcohol and carboxyl groups in fewer amounts were also observed. ToF-SIMS analysis, which can offer isotope identification with high mass resolution, showed that most of these carbon species were 13C-labeled. Unlike gas phase Fischer-Tropsch synthesis, no carbide was observed on mineral product surface during the experiment. Therefore, a reaction pathway is proposed for formation of dissolved linear alkane species in hydrothermal abiotic organic synthesis, where oxygen-bearing organic compounds are expected to form in aqueous products by way of alcohol and carboxyl groups on mineral catalyst surface.

  5. Generation of RNA in abiotic conditions.

    NASA Astrophysics Data System (ADS)

    di Mauro, Ernesto

    Generation of RNA in abiotic conditions. Ernesto Di Mauro Dipartimento di Genetica Bi-ologia Molecolare, Universit` "Sapienza" Roma, Italy. a At least four conditions must be satisfied for the spontaneous generation of (pre)-genetic poly-mers: 1) availability of precursors that are activated enough to spontaneously polymerize. Preliminary studies showed that (a) nucleic bases and acyclonucleosides can be synthesized from formamide H2NCOH by simply heating with prebiotically available mineral catalysts [last reviewed in (1)], and that b) nucleic bases can be phosphorylated in every possible posi-tion [2'; 3'; 5'; cyclic 2',3'; cyclic 3',5' (2)]. The higher stability of the cyclic forms allows their accumulation. 2) A polymerization mechanism. A reaction showing the formation of RNA polymers starting from prebiotically plausible precursors (3',5' cyclic GMP and 3', 5'cyclic AMP) was recently reported (3). Polymerization in these conditions is thermodynamically up-hill and an equilibrium is attained that limits the maximum length of the polymer produced to about 40 nucleotides for polyG and 100 nucleotides for polyA. 3) Ligation of the synthesized oligomers. If this type of reaction could occur according to a terminal-joining mechanism and could generate canonical 3',5' phosphodiester bonds, exponential growth would be obtained of the generated oligomers. This type of reaction has been reported (4) , limited to homogeneous polyA sequences and leading to the production of polyA dimers and tetramers. What is still missing are: 4) mechanisms that provide the proof of principle for the generation of sequence complexity. We will show evidence for two mechanisms providing this proof of principle for simple complementary sequences. Namely: abiotic sequence complementary-driven terminal ligation and sequence-complementary terminal growth. In conclusion: all the steps leading to the generation of RNA in abiotic conditions are satisfied. (1) R Saladino, C Crestini, F

  6. Unraveling the role of fungal symbionts in plant abiotic stress tolerance

    PubMed Central

    Singh, Lamabam Peter

    2011-01-01

    Fungal symbionts have been found to be associated with every plant studied in the natural ecosystem, where they colonize and reside entirely or partially in the internal tissues of their host plant. Fungal endophytes can express/form a range of different lifestyle/relationships with different host including symbiotic, mutualistic, commensalistic and parasitic in response to host genotype and environmental factors. In mutualistic association fungal endophyte can enhance growth, increase reproductive success and confer biotic and abiotic stress tolerance to its host plant. Since abiotic stress such as, drought, high soil salinity, heat, cold, oxidative stress and heavy metal toxicity is the common adverse environmental conditions that affect and limit crop productivity worldwide. It may be a promising alternative strategy to exploit fungal endophytes to overcome the limitations to crop production brought by abiotic stress. There is an increasing interest in developing the potential biotechnological applications of fungal endophytes for improving plant stress tolerance and sustainable production of food crops. Here we have described the fungal symbioses, fungal symbionts and their role in abiotic stress tolerance. A putative mechanism of stress tolerance by symbionts has also been covered. PMID:21512319

  7. Enhancing crop resilience to combined abiotic and biotic stress through the dissection of physiological and molecular crosstalk

    PubMed Central

    Kissoudis, Christos; van de Wiel, Clemens; Visser, Richard G. F.; van der Linden, Gerard

    2014-01-01

    Plants growing in their natural habitats are often challenged simultaneously by multiple stress factors, both abiotic and biotic. Research has so far been limited to responses to individual stresses, and understanding of adaptation to combinatorial stress is limited, but indicative of non-additive interactions. Omics data analysis and functional characterization of individual genes has revealed a convergence of signaling pathways for abiotic and biotic stress adaptation. Taking into account that most data originate from imposition of individual stress factors, this review summarizes these findings in a physiological context, following the pathogenesis timeline and highlighting potential differential interactions occurring between abiotic and biotic stress signaling across the different cellular compartments and at the whole plant level. Potential effects of abiotic stress on resistance components such as extracellular receptor proteins, R-genes and systemic acquired resistance will be elaborated, as well as crosstalk at the levels of hormone, reactive oxygen species, and redox signaling. Breeding targets and strategies are proposed focusing on either manipulation and deployment of individual common regulators such as transcription factors or pyramiding of non- (negatively) interacting components such as R-genes with abiotic stress resistance genes. We propose that dissection of broad spectrum stress tolerance conferred by priming chemicals may provide an insight on stress cross regulation and additional candidate genes for improving crop performance under combined stress. Validation of the proposed strategies in lab and field experiments is a first step toward the goal of achieving tolerance to combinatorial stress in crops. PMID:24904607

  8. High-temperature measurements of Q-factor in rotated X-cut quartz resonators

    NASA Technical Reports Server (NTRS)

    Fritz, I. J.

    1981-01-01

    The Q-factors of piezoelectric resonators fabricated from natural and synthetic quartz with a 34 deg rotated X-cut orientation were measured at temperatures up to 325 C. The synthetic material, which was purified by electrolysis, retains a higher enough Q to be suitable for high temperature pressure-transducer applications, whereas the natural quartz is excessively lossy above 200 C for this application. The results are compared to results obtained previously at AT-cut resonators.

  9. Temperature and donor concentration dependence of the conduction electron Lande g-factor in silicon

    NASA Astrophysics Data System (ADS)

    Konakov, Anton A.; Ezhevskii, Alexander A.; Soukhorukov, Andrey V.; Guseinov, Davud V.; Popkov, Sergey A.; Burdov, Vladimir A.

    2013-12-01

    Temperature and donor concentration dependence of the conduction electron g-factor in silicon has been investigated both experimentally and theoretically. We performed electron spin resonance experiments on Si samples doped with different densities of phosphorus and lithium. Theoretical consideration is based on the renormalization of the electron energy in a weak magnetic field by the interaction with possible perturbing agents, such as phonons and impurity centers. In the second-order perturbation theory interaction of the electron subsystem with the lattice vibrations as well as ionized donors results in decreasing the conduction electron g-factor, which becomes almost linear function both of temperature and impurity concentration.

  10. Genetic Dissection of Abiotic Stress Tolerance in Sorghum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sorghum, the fifth most important cereal crop in the world is a highly versatile crop and an excellent model species due to its overall tolerance to a number of abiotic stress conditions. To gain a better understanding of the physiological and genetic basis of abiotic stress tolerance in sorghum w...

  11. Identification of possible factors influencing temperatures elevation during implant site preparation with piezoelectric technique

    PubMed Central

    Lamazza, Luca; Laurito, Domenica; Lollobrigida, Marco; Brugnoletti, Orlando; Garreffa, Girolamo; De Biase, Alberto

    2014-01-01

    Summary Background Overheating during implant site preparation negatively affects the osseointegration process as well the final outcome of implant rehabilitations. Piezoelectric techniques seem to provide to a gentle implant preparation although few scientific reports have investigated the heat generation and its underlying factors. Purpose To investigate, through a proper methodological approach, the main factors influencing temperature rise during piezoelectric implant site preparation. Materials and methods Different piezoelectric tips (IM1s, IM2, P2-3, IM3, Mectron Medical Technology, Carasco, Italy) have been tested. The experimental set-up consisted in a mechanical positioning device equipped with a load cell and a fluoroptic thermometer. Results The first tip of the sequence (IM1s) generated the highest temperature increasing (ΔT). The diamond tips (IM1s and P2-3) determined higher ΔT values than the smooth tips (IM2 and IM3). Further tests with IM1s suggested that the temperature elevation during the first thirty seconds may be predictive of the maximal temperature as well as of the overall thermal impact. Conclusions Working load, working movements management and bone features resulted to be the main factors influencing temperature rise during piezoelectric implant site preparation. Irrigant temperature and clogging effect may also synergically contribute to the heat generation. PMID:25774245

  12. Cell wall remodeling under abiotic stress

    PubMed Central

    Tenhaken, Raimund

    2015-01-01

    Plants exposed to abiotic stress respond to unfavorable conditions on multiple levels. One challenge under drought stress is to reduce shoot growth while maintaining root growth, a process requiring differential cell wall synthesis and remodeling. Key players in this process are the formation of reactive oxygen species (ROS) and peroxidases, which initially cross-link phenolic compounds and glycoproteins of the cell walls causing stiffening. The function of ROS shifts after having converted all the peroxidase substrates in the cell wall. If ROS-levels remain high during prolonged stress, OH°-radicals are formed which lead to polymer cleavage. In concert with xyloglucan modifying enzymes and expansins, the resulting cell wall loosening allows further growth of stressed organs. PMID:25709610

  13. Proline accumulation is a general response to abiotic stress in the date palm tree (Phoenix dactylifera L.).

    PubMed

    Yaish, M W

    2015-01-01

    Plants exposed to certain abiotic stress conditions tend to produce the amino acid proline, which acts as an active osmolyte, a metal chelator, an antioxidant, and a signaling molecule. There is increasing evidence that proline accumulates in plants due to a wide range of abiotic stress, in particular high soil salinity and drought. Therefore, proline content is often used as a marker-assisted breeding tool aimed at improving drought and salinity tolerance. In this study, it was investigated whether proline accumulation in date palm (Phoenix dactylifera L.) seedlings occurs solely due to high salinity and drought stresses or due to other unspecified abiotic stresses, including salinity and salinity shock, drought, extreme temperatures, and abscisic acid. The free proline assays revealed that this amino acid over-accumulated in the roots and leaves of each stress-treated plant, and was remarkably high when leaves were exposed to suboptimum temperatures and salinity stress. These results indicate that the production of proline is a common response to various abiotic stresses and its differential accumulation cannot be used as a molecular marker in date palm breeding programs aimed at improving drought or salinity tolerance traits in date palms. This conclusion is consistent with the theory that the molecular outcomes of abiotic stresses are often non-specific. PMID:26345930

  14. Mass spectrometry-based plant metabolomics: Metabolite responses to abiotic stress.

    PubMed

    Jorge, Tiago F; Rodrigues, João A; Caldana, Camila; Schmidt, Romy; van Dongen, Joost T; Thomas-Oates, Jane; António, Carla

    2016-09-01

    Metabolomics is one omics approach that can be used to acquire comprehensive information on the composition of a metabolite pool to provide a functional screen of the cellular state. Studies of the plant metabolome include analysis of a wide range of chemical species with diverse physical properties, from ionic inorganic compounds to biochemically derived hydrophilic carbohydrates, organic and amino acids, and a range of hydrophobic lipid-related compounds. This complexitiy brings huge challenges to the analytical technologies employed in current plant metabolomics programs, and powerful analytical tools are required for the separation and characterization of this extremely high compound diversity present in biological sample matrices. The use of mass spectrometry (MS)-based analytical platforms to profile stress-responsive metabolites that allow some plants to adapt to adverse environmental conditions is fundamental in current plant biotechnology research programs for the understanding and development of stress-tolerant plants. In this review, we describe recent applications of metabolomics and emphasize its increasing application to study plant responses to environmental (stress-) factors, including drought, salt, low oxygen caused by waterlogging or flooding of the soil, temperature, light and oxidative stress (or a combination of them). Advances in understanding the global changes occurring in plant metabolism under specific abiotic stress conditions are fundamental to enhance plant fitness and increase stress tolerance. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 35:620-649, 2016. PMID:25589422

  15. Global Patterns of Stem CO2 Efflux in Forests and its Biotic and Abiotic Controls

    NASA Astrophysics Data System (ADS)

    Yang, J.

    2015-12-01

    Forest stem CO2 efflux (ES) plays an important role in the carbon balance of forest ecosystems. However, its primary controls at the global scale are poorly understood and observation-based global estimates are lacking. We synthesized data from XX published studies across global forest ecosystems and examined the relationships between annual ES and abiotic factors (mean annual temperature (MAT), mean annual precipitation (MAP)) and biotic factors (gross primary production (GPP), net primary production (NPP), leaf area index (LAI), soil CO2 efflux (RS), root CO2 efflux (RA), foliar CO2 efflux, basal area, and stand age). Based on our compiled datasets, the mean annual ES was 90 ± 43 g C m-2 yr-1, 160 ± 79 g C m-2 yr-1 and 501 ± 363 g C m-2 yr-1 for boreal, temperate, and tropical forest ecosystems, respectively. Average apparent Q10 of ES for boreal forests was 1.85, 2.29 for temperate forests, and 2.26 for tropical forests. Globally, MAT and MAP explained 32% and 24% of the variation in annual ES, respectively. Positive linear relationships exist between ES and forest production (GPP and NPP), LAI, RS, and RA in different forest ecosystems. These correlations hold for the global dataset, as well as for temperate and tropical forest ecosystems independently. In addition, we found no correlation between ES and both RS and RA after accounting for temperature and GPP effects. The predicted a global annual ES was about 6.1Pg C yr-1.

  16. Relations of Tualatin River water temperatures to natural and human-caused factors

    USGS Publications Warehouse

    Risley, John C.

    1997-01-01

    Aquatic research has long shown that the survival of cold-water fish, such as salmon and trout, decreases markedly as water temperatures increase above a critical threshold, particularly during sensitive life stages of the fish. In an effort to improve the overall health of aquatic ecosystems, the State of Oregon in 1996 adopted a maximum water-temperature standard of 17.8 degrees Celsius (68 degrees Fahrenheit), based on a 7-day moving average of daily maximum temperatures, for most water bodies in the State. Anthropogenic activities are not permitted to raise the temperature of a water body above this level. In the Tualatin River, a tributary of the Willamette River located in northwestern Oregon, water temperatures periodically surpass this threshold during the low-flow summer and fall months.An investigation by the U.S. Geological Survey quantified existing seasonal, diel, and spatial patterns of water temperatures in the main stem of the river, assessed the relation of water temperatures to natural climatic conditions and anthropogenic factors (such as wastewater-treatment-plant effluent and modification of riparian shading), and assessed the impact of various flow management practices on stream temperatures. Half-hourly temperature measurements were recorded at 13 monitoring sites from river mile (RM) 63.9 to RM 3.4 from May to November of 1994. Four synoptic water- temperature surveys also were conducted in the upstream and downstream vicinities of two wastewater-treatment-plant outfalls. Temperature and streamflow time-series data were used to calibrate two dynamic-flow heat-transfer models, DAFLOW-BLTM (RM 63.9-38.4) and CE-QUAL-W2 (RM 38.4-3.4). Simulations from the models provided a basis for approximating 'natural' historical temperature patterns, performing effluent and riparian-shading sensitivity analyses, and evaluating mitigation management scenarios under 1994 climatic conditions. Findings from the investigation included (1) under 'natural

  17. Temperature trumps light: Teasing apart interactive factors controlling non-indigenous Zostera japonica growth

    EPA Science Inventory

    In the Pacific Northwest Zostera marina and Z. japonica co-exist by occupying separate elevation niches. We conducted two mesocosm experiments to evaluate light and temperature as factors controlling the disjunct distribution of congeners. The first study tests the hypothesis t...

  18. Temperature as a determinant factor for increased and reproducible in vitro pollen germination in Arabidopsis thaliana

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite much effort, a robust protocol for in vitro germination of Arabidopsis thaliana pollen was still elusive. Here we show that controlled temperatures, a largely disregarded factor in previous studies, and a simple optimized medium, solidified or liquid, yielded pollen germination rates above 8...

  19. Temperature-Related Risk Factors for the Occurrence of Campylobacter in Broilers in Iceland

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Introduction A summertime increased risk of Campylobacter is well-established in humans and broilers. Our objective was to identify temperature-related risk factors for the colonization of broiler flocks with Campylobacter in Iceland, with an assumption that flies play a role in the epidemiology an...

  20. Biotic and Abiotic Degradation of CL-20 and RDX in Soils

    SciTech Connect

    Crocker, Fiona H.; Thompson, Karen T.; Szecsody, Jim E.; Fredrickson, Herbert L.

    2005-11-01

    The caged cyclic nitramine 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) is a new explosive that has the potential to replace existing military explosives, but little is known about its environmental toxicity, transport, and fate. We quantified and compared the aerobic environmental fate of CL-20 to the widely used cyclic nitramine explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in surface and subsurface soil microcosms. Soil-free controls and biologically mediated processes. Both abiotic and biological processes significantly degraded CL-20 in all soils examined. Apparent abiotic, first-order degradation rates (k) for CL-20 were not significantly different between soil-free controls (0.018 < k < 0.030 d-1) and biologically attenuated soil controls (0.003 abiotic degradation rates of RDX were generally slower (0 < k < 0.032 d-1) than abiotic CL-20 degradation rates. In biologically active soil microcosms amended with glucose aerobic RDX degradation rates varied between 0.010 and 0.474 d-1. Biodegradation was a key factor in determining the environmental fate of RDX, while a combination of biotic and abiotic processes was important with CL-20. Our data suggest that CL-20 should be less recalcitrant than RDX in aerobic soils.

  1. Abiotic stress QTL in lettuce crop–wild hybrids: comparing greenhouse and field experiments

    PubMed Central

    Hartman, Yorike; Hooftman, Danny A P; Uwimana, Brigitte; Schranz, M Eric; van de Wiel, Clemens C M; Smulders, Marinus J M; Visser, Richard G F; Michelmore, Richard W; van Tienderen, Peter H

    2014-01-01

    The development of stress-tolerant crops is an increasingly important goal of current crop breeding. A higher abiotic stress tolerance could increase the probability of introgression of genes from crops to wild relatives. This is particularly relevant to the discussion on the risks of new GM crops that may be engineered to increase abiotic stress resistance. We investigated abiotic stress QTL in greenhouse and field experiments in which we subjected recombinant inbred lines from a cross between cultivated Lactuca sativa cv. Salinas and its wild relative L. serriola to drought, low nutrients, salt stress, and aboveground competition. Aboveground biomass at the end of the rosette stage was used as a proxy for the performance of plants under a particular stress. We detected a mosaic of abiotic stress QTL over the entire genome with little overlap between QTL from different stresses. The two QTL clusters that were identified reflected general growth rather than specific stress responses and colocated with clusters found in earlier studies for leaf shape and flowering time. Genetic correlations across treatments were often higher among different stress treatments within the same experiment (greenhouse or field), than among the same type of stress applied in different experiments. Moreover, the effects of the field stress treatments were more correlated with those of the greenhouse competition treatments than to those of the other greenhouse stress experiments, suggesting that competition rather than abiotic stress is a major factor in the field. In conclusion, the introgression risk of stress tolerance (trans-)genes under field conditions cannot easily be predicted based on genomic background selection patterns from controlled QTL experiments in greenhouses, especially field data will be needed to assess potential (negative) ecological effects of introgression of these transgenes into wild relatives. PMID:25360276

  2. Factors contributing to the temperature beneath plaster or fiberglass cast material

    PubMed Central

    Hutchinson, Michael J; Hutchinson, Mark R

    2008-01-01

    Background Most cast materials mature and harden via an exothermic reaction. Although rare, thermal injuries secondary to casting can occur. The purpose of this study was to evaluate factors that contribute to the elevated temperature beneath a cast and, more specifically, evaluate the differences of modern casting materials including fiberglass and prefabricated splints. Methods The temperature beneath various types (plaster, fiberglass, and fiberglass splints), brands, and thickness of cast material were measured after they were applied over thermometer which was on the surface of a single diameter and thickness PVC tube. A single layer of cotton stockinette with variable layers and types of cast padding were placed prior to application of the cast. Serial temperature measurements were made as the cast matured and reached peak temperature. Time to peak, duration of peak, and peak temperature were noted. Additional tests included varying the dip water temperature and assessing external insulating factors. Ambient temperature, ambient humidity and dip water freshness were controlled. Results Outcomes revealed that material type, cast thickness, and dip water temperature played key roles regarding the temperature beneath the cast. Faster setting plasters achieved peak temperature quicker and at a higher level than slower setting plasters. Thicker fiberglass and plaster casts led to greater peak temperature levels. Likewise increasing dip-water temperature led to elevated temperatures. The thickness and type of cast padding had less of an effect for all materials. With a definition of thermal injury risk of skin injury being greater than 49 degrees Celsius, we found that thick casts of extra fast setting plaster consistently approached dangerous levels (greater than 49 degrees for an extended period). Indeed a cast of extra-fast setting plaster, 20 layers thick, placed on a pillow during maturation maintained temperatures over 50 degrees of Celsius for over 20

  3. A New Method to Measure Temperature and Burner Pattern Factor Sensing for Active Engine Control

    NASA Technical Reports Server (NTRS)

    Ng, Daniel

    1999-01-01

    The determination of the temperatures of extended surfaces which exhibit non-uniform temperature variation is very important for a number of applications including the "Burner Pattern Factor" (BPF) of turbine engines. Exploratory work has shown that use of BPF to control engine functions can result in many benefits, among them reduction in engine weight, reduction in operating cost, increase in engine life, while attaining maximum engine efficiency. Advanced engines are expected to operate at very high temperature to achieve high efficiency. Brief exposure of engine components to higher than design temperatures due to non-uniformity in engine burner pattern can reduce engine life. The engine BPF is a measure of engine temperature uniformity. Attainment of maximum temperature uniformity and high temperatures is key to maximum efficiency and long life. A new approach to determine through the measurement of just one radiation spectrum by a multiwavelength pyrometer is possible. This paper discusses a new temperature sensing approach and its application to determine the BPF.

  4. The abiotic contribution to total CO2 flux for soils in arid zone

    NASA Astrophysics Data System (ADS)

    Ma, J.; Li, Y.; Liu, R.

    2015-07-01

    As an important component of ecosystem carbon budgets, soil carbon dioxide (CO2) flux is determined by a combination of a series of biotic and abiotic processes. Although there is evidence that the abiotic component can be important in total soil CO2 flux, its relative importance has never been systematically assessed. In this study, the total soil CO2 flux (Rtotal) was partitioned into biotic (Rbiotic) and abiotic (Rabiotic) components over eight typical landscapes in a desert-oasis ecotone, including cotton field, hops field, halophyte garden, reservoir edge, native saline desert, alkaline soil, dune crest and interdune lowland in the Gurbantunggut Desert, and the relative importance of these two components was analyzed. Results showed that Rabiotic always contributed to Rtotal for the eight landscapes, but the degree of contribution varied greatly. In the cotton and hops fields, the ratio of Rabiotic to Rtotal was extremely low (< 10 %); whereas Rabiotic was dominant in the alkaline soil and dune crest. Statistically, Rabiotic/Rtotal decreased logarithmically with rising Rbiotic, suggesting that Rabiotic strongly affected Rtotal when Rbiotic was low. This pattern confirms that soil CO2 flux is predominantly biological in most ecosystems, but Rabiotic can dominate when biological processes are weak. On a diurnal basis, Rabiotic resulted in no net gain or loss of carbon but its effect on instantaneous CO2 flux was significant. Temperature dependence of Rtotal varied among the eight landscapes, determined by the predominant components of CO2 flux: with Rbiotic driven by soil temperature and Rabiotic regulated by the rate of change in temperature. Namely, declining temperature resulted in negative Rabiotic (CO2 went into soil), while rising temperature resulted in a positive Rabiotic (CO2 released from soil). Furthermore, without recognition of Rabiotic, Rbiotic would have been either overestimated (for daytime) or underestimated (for nighttime). Thus, recognition

  5. On the use of abiotic surrogates to describe marine benthic biodiversity

    NASA Astrophysics Data System (ADS)

    McArthur, M. A.; Brooke, B. P.; Przeslawski, R.; Ryan, D. A.; Lucieer, V. L.; Nichol, S.; McCallum, A. W.; Mellin, C.; Cresswell, I. D.; Radke, L. C.

    2010-06-01

    A growing need to manage marine biodiversity sustainably at local, regional and global scales cannot be met by applying existing biological data. Abiotic surrogates of biodiversity are thus increasingly valuable in filling the gaps in our knowledge of biodiversity patterns, especially identification of hotspots, habitats needed by endangered or commercially valuable species and systems or processes important to the sustained provision of ecosystem services. This review examines the use of abiotic variables as surrogates for patterns in benthic biodiversity with particular regard to how variables are tied to processes affecting species richness and how easily those variables can be measured at scales relevant to resource management decisions. Direct gradient variables such as salinity, oxygen concentration and temperature can be strong predictive variables for larger systems, although local stability of water quality may prevent usefulness of these factors at fine spatial scales. Biological productivity has complex relationships with benthic biodiversity and although the development of local and regional models cannot accurately predict outside the range of their biological sampling, remote sensing may provide useful information. Indeed, interpolated values are available for much of the world's seas, and these are continually being refined by the collection of remote sensing and field data. Sediment variables often exhibit complex relationships with benthic biodiversity. The strength of the relationship between any one sediment variable and biodiversity may depend on the state of another sediment variable in that system. Percentage mud, percentage gravel, rugosity and compaction hold the strongest independent predictive power. Rugosity and the difference between gravel and finer sediments can be established using acoustic methods, but to quantify grain size and measure compaction, a sample is necessary. Pure spatial variables such as latitude, longitude and depth

  6. Induction temperature of human heat shock factor is reprogrammed in a Drosophila cell environment

    NASA Astrophysics Data System (ADS)

    Clos, Joachim; Rabindran, Sridhar; Wisniewski, Jan; Wu, Carl

    1993-07-01

    HEAT shock factor (HSF)1,2, the transcriptional activator of eukaryotic heat shock genes, is induced to bind DNA by a monomer to trimer transition involving leucine zipper interactions3,4. Although this mode of regulation is shared among many eukaryotic species, there is variation in the temperature at which HSF binding activity is induced. We investigated the basis of this variation by analysing the response of a human HSF expressed in Drosophila cells and Drosophila HSF expressed in human cells. We report here that the temperature that induces DNA binding and trimerization of human HSF in Drosophila was decreased by ~10 °C to the induction temperature for the host cell, whereas Drosophila HSF expressed in human cells was constitutively active. The results indicate that the activity of HSF in vivo is not a simple function of the absolute environmental temperature.

  7. Biomass allocation and C-N-P stoichiometry in C3 and C4 crops under abiotic stress

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biomass allocation to structural, metabolic and reproductive organs as well as their carbon, nitrogen and phosphorus (C-N-P) profiles and ratios (C:N, C:P, and N:P) were estimated in C3 and C4 crop plants subjected to multiple abiotic stresses (i.e., combination of temperature and water stress level...

  8. Topological characteristics of target genes regulated by abiotic-stress-responsible miRNAs in a rice interactome network.

    PubMed

    Zhang, Linzhong; Xuan, Hongdong; Zuo, Yongchun; Xu, Gaojian; Wang, Ping; Song, Youhong; Zhang, Shihua

    2016-05-01

    A great number of microRNAs (miRNAs) have been identified in responding and acting in gene regulatory networks associated with plant tolerance to abiotic stress conditions, such as drought, salinity, and high temperature. The topological exploration of target genes regulated by abiotic-stress-responsible miRNAs (ASRmiRs) in a network facilitates to discover the molecular basis of plant abiotic stress response. This study was based on the staple food rice (Oryza sativa) in which ASRmiRs were manually curated. After having compared the topological properties of target genes (stress-miR-targets) with those (non-stress-miR-targets) not regulated by ASRmiRs in a rice interactome network, we found that stress-miR-targets exhibited distinguishable topological properties. The interaction probability analysis and k-core decomposition showed that stress-miR-targets preferentially interacted with non-stress-miR-targets and located at the peripheral positions in the network. Our results indicated an obvious topological distinction between the two types of genes, reflecting the specific mechanisms of action of stress-miR-targets in rice abiotic stress response. Also, the results may provide valuable clues to elucidate molecular mechanisms of crop response to abiotic stress. PMID:26830287

  9. Managing Abiotic Factors of Compost to Increase Soilborne Disease Suppression

    ERIC Educational Resources Information Center

    Griffin, Deirdre E.

    2012-01-01

    Soilborne pathogens can devastate crops, causing economic losses for farmers due to reduced yields and expensive management practices. Fumigants and fungicides have harmful impacts on the surrounding environment and can be toxic to humans. Therefore, alternative methods of disease management are important. The disease suppressive abilities of…

  10. Chemical Priming of Plants Against Multiple Abiotic Stresses: Mission Possible?

    PubMed

    Savvides, Andreas; Ali, Shawkat; Tester, Mark; Fotopoulos, Vasileios

    2016-04-01

    Crop plants are subjected to multiple abiotic stresses during their lifespan that greatly reduce productivity and threaten global food security. Recent research suggests that plants can be primed by chemical compounds to better tolerate different abiotic stresses. Chemical priming is a promising field in plant stress physiology and crop stress management. We review here promising chemical agents such as sodium nitroprusside, hydrogen peroxide, sodium hydrosulfide, melatonin, and polyamines that can potentially confer enhanced tolerance when plants are exposed to multiple abiotic stresses. The challenges and opportunities of chemical priming are addressed, with the aim to boost future research towards effective application in crop stress management. PMID:26704665

  11. Temperature dependence of the electron spin g factor in CdTe and InP

    NASA Astrophysics Data System (ADS)

    Pfeffer, Pawel; Zawadzki, Wlodek

    2012-04-01

    Temperature dependence of the electron spin g factors in bulk CdTe and InP is calculated and compared with experiment. It is assumed that the only modification of the band structure related to temperature is a dilatation change in the fundamental energy gap. The dilatation changes of fundamental gaps are calculated for both materials using available experimental data. Computations of the band structures in the presence of a magnetic field are carried out employing five-level P.p model appropriate for medium-gap semiconductors. In particular, the model takes into account spin splitting due to bulk inversion asymmetry (BIA) of the materials. The resulting theoretical effective masses and g factors increase with electron energy due to band nonparabolicity. Average g values are calculated by summing over populated Landau and spin levels properly accounting for the thermal distribution of electrons in the band. It is shown that the spin splitting due to BIA in the presence of a magnetic field gives observable contributions to g values. Our calculations are in good agreement with experiments in the temperature range of 0 K to 300 K for CdTe and 0 K to 180 K for InP. The temperature dependence of g is stronger in CdTe than in InP due to different signs of band-edge g values in the two materials. Good agreement between the theory and experiments strongly indicates that the temperature dependence of spin g factors is correctly explained. In addition, we discuss formulas for the energy dependence of spin g factor due to band nonparabolicity, which are liable to misinterpretation.

  12. Environmental hazard assessment of chemicals and products. Part VI. Abiotic degradation in the troposphere.

    PubMed

    Klöpffer, W

    1996-09-01

    The atmosphere constitutes an important sink for many volatile and semivolatile organic compounds (Part II). Even non-volatile compounds may enter the troposphere due to incomplete burning of fuel and industrial, agricultural and traffic-related processes. Depending on vapour pressure, temperature and content of aerosol particles, chemicals prefer the free gas phase, the surface of the particles, or both compartments. Polar compounds (low Henry-coefficient) may dissolve in cloud- and fog droplets. Clearly, the prefered compartment influences the dominant abiotic degradation path. In this paper, a survey is given about the distribution and degradation pathways of chemicals in the troposphere. In the free gas phase of the troposphere, the reaction with OH-radicals is the dominant degradation path. In addition, the reactions with ozone and nitrate-radicals, and direct photochemical reactions also play a role in abiotic degradation. PMID:8784998

  13. Abiotic uptake of gases by organic soils

    NASA Astrophysics Data System (ADS)

    Smagin, A. V.

    2007-12-01

    Methodological and experimental studies of the abiotic uptake of gaseous substances by organic soils were performed. The static adsorption method of closed vessels for assessing the interaction of gases with the solid and liquid soil phases and the dynamic method of determining the sorption isotherms of gases by soils were analyzed. The theoretical substantiation of the methods and their practical implementations on the basis of a PGA-7 portable gas analyzer (Russia) were considered. Good agreement between the equilibrium sorption isotherms of the gases and the Langmuir model was revealed; for the real ranges of natural gas concentrations, this model can be reduced to the linear Henry equation. The limit values of the gas sorption (Langmuir monolayer capacity) are typical for dry samples; they vary from 670 4000 g/m3 for methane and oxygen to 20 000 25 000 g/m3 for carbon dioxide. The linear distribution coefficients of gases between the solid and gas phases of organic soils (Henry constants) are 8 18 units for poorly sorbed gases (O2, CH4) and 40 60 units for CO2. The kinetics of the chemicophysical uptake of gases by the soil studied is linear in character and obeys the relaxation kinetic model of the first order with the corresponding relaxation constants, which vary from 1 h -1 in wet samples to 10 h -1 in dry samples.

  14. Genome-Wide Analysis of the AP2/ERF Superfamily Genes and their Responses to Abiotic Stress in Medicago truncatula

    PubMed Central

    Shu, Yongjun; Liu, Ying; Zhang, Jun; Song, Lili; Guo, Changhong

    2016-01-01

    The AP2/ERF superfamily is a large, plant-specific transcription factor family that is involved in many important processes, including plant growth, development, and stress responses. Using Medicago truncatula genome information, we identified and characterized 123 putative AP2/ERF genes, which were named as MtERF1–123. These genes were classified into four families based on phylogenetic analysis, which is consistent with the results of other plant species. MtERF genes are distributed throughout all chromosomes but are clustered on various chromosomes due to genomic tandem and segmental duplication. Using transcriptome, high-throughput sequencing data, and qRT-PCR analysis, we assessed the expression patterns of the MtERF genes in tissues during development and under abiotic stresses. In total, 87 MtERF genes were expressed in plant tissues, most of which were expressed in specific tissues during development or under specific abiotic stress treatments. These results support the notion that MtERF genes are involved in developmental regulation and environmental responses in M. truncatula. Furthermore, a cluster of DREB subfamily members on chromosome 6 was induced by both cold and freezing stress, representing a positive gene regulatory response under low temperature stress, which suggests that these genes might contribute to freezing tolerance to M. truncatula. In summary, our genome-wide characterization, evolutionary analysis, and expression pattern analysis of MtERF genes in M. truncatula provides valuable information for characterizing the molecular functions of these genes and utilizing them to improve stress tolerance in plants. PMID:26834762

  15. Olivine Weathering: Abiotic Versus Biotic Processes as Possible Biosignatures

    NASA Technical Reports Server (NTRS)

    Longazo, T. G.; Wentworth, S. J.; McKay, D. S.; Southam, G.; Clemett, S. J.

    2001-01-01

    A preliminary study to determine how abiotic versus biotic processes affect the weathering of olivine crystals. Perhaps the differences between these weathering processes could be used as biosignatures. Additional information is contained in the original extended abstract.

  16. Abiotic stress responses in plant roots: a proteomics perspective

    PubMed Central

    Ghosh, Dipanjana; Xu, Jian

    2014-01-01

    Abiotic stress conditions adversely affect plant growth, resulting in significant decline in crop productivity. To mitigate and recover from the damaging effects of such adverse environmental conditions, plants have evolved various adaptive strategies at cellular and metabolic levels. Most of these strategies involve dynamic changes in protein abundance that can be best explored through proteomics. This review summarizes comparative proteomic studies conducted with roots of various plant species subjected to different abiotic stresses especially drought, salinity, flood, and cold. The main purpose of this article is to highlight and classify the protein level changes in abiotic stress response pathways specifically in plant roots. Shared as well as stressor-specific proteome signatures and adaptive mechanism(s) are simultaneously described. Such a comprehensive account will facilitate the design of genetic engineering strategies that enable the development of broad-spectrum abiotic stress-tolerant crops. PMID:24478786

  17. Relative Importance of Biotic and Abiotic Forces on the Composition and Dynamics of a Soft-Sediment Intertidal Community

    PubMed Central

    Barbeau, Myriam A.

    2016-01-01

    Top-down, bottom-up, middle-out and abiotic factors are usually viewed as main forces structuring biological communities, although assessment of their relative importance, in a single study, is rarely done. We quantified, using multivariate methods, associations between abiotic and biotic (top-down, bottom-up and middle-out) variables and infaunal population/community variation on intertidal mudflats in the Bay of Fundy, Canada, over two years. Our analysis indicated that spatial structural factors like site and plot accounted for most of the community and population variation. Although we observed a significant relationship between the community/populations and the biotic and abiotic variables, most were of minor importance relative to the structural factors. We suggest that community and population structure were relatively uncoupled from the structuring influences of biotic and abiotic factors in this system because of high concentrations of resources that sustain high densities of infauna and limit exploitative competition. Furthermore, we hypothesize that the infaunal community primarily reflects stochastic spatial events, namely a “first come, first served” process. PMID:26790098

  18. ROS-mediated abiotic stress-induced programmed cell death in plants

    PubMed Central

    Petrov, Veselin; Hille, Jacques; Mueller-Roeber, Bernd; Gechev, Tsanko S.

    2015-01-01

    During the course of their ontogenesis plants are continuously exposed to a large variety of abiotic stress factors which can damage tissues and jeopardize the survival of the organism unless properly countered. While animals can simply escape and thus evade stressors, plants as sessile organisms have developed complex strategies to withstand them. When the intensity of a detrimental factor is high, one of the defense programs employed by plants is the induction of programmed cell death (PCD). This is an active, genetically controlled process which is initiated to isolate and remove damaged tissues thereby ensuring the survival of the organism. The mechanism of PCD induction usually includes an increase in the levels of reactive oxygen species (ROS) which are utilized as mediators of the stress signal. Abiotic stress-induced PCD is not only a process of fundamental biological importance, but also of considerable interest to agricultural practice as it has the potential to significantly influence crop yield. Therefore, numerous scientific enterprises have focused on elucidating the mechanisms leading to and controlling PCD in response to adverse conditions in plants. This knowledge may help develop novel strategies to obtain more resilient crop varieties with improved tolerance and enhanced productivity. The aim of the present review is to summarize the recent advances in research on ROS-induced PCD related to abiotic stress and the role of the organelles in the process. PMID:25741354

  19. Impacts of biotic and abiotic stress on major quality attributing metabolites of coffee beans.

    PubMed

    Vaddadi, Sridevi; Parvatam, Giridhar

    2015-03-01

    Biotic stress factors such as Rhizopus oligosporus and Aspergillus niger mycelial extracts and abiotic elements methyljasmonate (MJ) and salicylic acid (SA), when administered through floral spray to Coffea canephora, showed significant influence on major bioactive metabolites of beans. Up to 42% caffeine, 39% theobromine and 46% trigonelline, along with 32% cafestol and kahweol content elevation was evident under respective elicitor treatments. Over all, the surge in respective metabolites depends on elicitor stress type and concentration. Abiotic factors MJ and SA were found to be efficient at 1 to 5 microM concentration in augmenting all the metabolites, compared to R. oligosporus and A. niger spray at 0.5-2.0% wherein the response was moderate as compared to abiotic stress, however significant compared to control. Though this elevation in caffeine, theobromine, cafestol and kahweol is not warranted from quality point of view, increase in trigonelline improves coffee quality. Besides increase in metabolites, stress mediated augmentation of bioactive compounds in coffee has a wide scope for studying gene expression pattern. PMID:25895259

  20. Abiotic Stresses: Insight into Gene Regulation and Protein Expression in Photosynthetic Pathways of Plants.

    PubMed

    Nouri, Mohammad-Zaman; Moumeni, Ali; Komatsu, Setsuko

    2015-01-01

    Global warming and climate change intensified the occurrence and severity of abiotic stresses that seriously affect the growth and development of plants,especially, plant photosynthesis. The direct impact of abiotic stress on the activity of photosynthesis is disruption of all photosynthesis components such as photosystem I and II, electron transport, carbon fixation, ATP generating system and stomatal conductance. The photosynthetic system of plants reacts to the stress differently, according to the plant type, photosynthetic systems (C₃ or C₄), type of the stress, time and duration of the occurrence and several other factors. The plant responds to the stresses by a coordinate chloroplast and nuclear gene expression. Chloroplast, thylakoid membrane, and nucleus are the main targets of regulated proteins and metabolites associated with photosynthetic pathways. Rapid responses of plant cell metabolism and adaptation to photosynthetic machinery are key factors for survival of plants in a fluctuating environment. This review gives a comprehensive view of photosynthesis-related alterations at the gene and protein levels for plant adaptation or reaction in response to abiotic stress. PMID:26343644

  1. Abiotic Stresses: Insight into Gene Regulation and Protein Expression in Photosynthetic Pathways of Plants

    PubMed Central

    Nouri, Mohammad-Zaman; Moumeni, Ali; Komatsu, Setsuko

    2015-01-01

    Global warming and climate change intensified the occurrence and severity of abiotic stresses that seriously affect the growth and development of plants, especially, plant photosynthesis. The direct impact of abiotic stress on the activity of photosynthesis is disruption of all photosynthesis components such as photosystem I and II, electron transport, carbon fixation, ATP generating system and stomatal conductance. The photosynthetic system of plants reacts to the stress differently, according to the plant type, photosynthetic systems (C3 or C4), type of the stress, time and duration of the occurrence and several other factors. The plant responds to the stresses by a coordinate chloroplast and nuclear gene expression. Chloroplast, thylakoid membrane, and nucleus are the main targets of regulated proteins and metabolites associated with photosynthetic pathways. Rapid responses of plant cell metabolism and adaptation to photosynthetic machinery are key factors for survival of plants in a fluctuating environment. This review gives a comprehensive view of photosynthesis-related alterations at the gene and protein levels for plant adaptation or reaction in response to abiotic stress. PMID:26343644

  2. Comparative study of biogenic and abiotic iron-containing materials

    NASA Astrophysics Data System (ADS)

    Cherkezova-Zheleva, Z.; Shopska, M.; Paneva, D.; Kovacheva, D.; Kadinov, G.; Mitov, I.

    2016-12-01

    Series of iron-based biogenic materials prepared by cultivation of Leptothrix group of bacteria in different feeding media ( Sphaerotilus-Leptothrix group of bacteria isolation medium, Adler, Lieske and silicon-iron-glucose-peptone) were studied. Control samples were obtained in the same conditions and procedures but the nutrition media were not infected with bacteria, i.e. they were sterile. Room and low temperature Mössbauer spectroscopy, powder X-ray diffraction (XRD), and infrared spectroscopy (IRS) were used to reveal the composition and physicochemical properties of biomass and respective control samples. Comparative analysis showed differences in their composition and dispersity of present phases. Sample composition included different ratio of nanodimensional iron oxyhydroxide and oxide phases. Relaxation phenomena such as superparamagnetism or collective magnetic excitation behaviour were registered for some of them. The experimental data showed that the biogenic materials were enriched in oxyhydroxides of high dispersion. Catalytic behaviour of a selected biomass and abiotic material were studied in the reaction of CO oxidation. In situ diffuse-reflectance (DR) IRS was used to monitor the phase transformations in the biomass and CO conversion.

  3. Uptake of inorganic phosphate is a limiting factor for Saccharomyces cerevisiae during growth at low temperatures.

    PubMed

    Vicent, Isabel; Navarro, Alfonso; Mulet, Jose M; Sharma, Sukesh; Serrano, Ramón

    2015-05-01

    The fermenting ability of Saccharomyces at low temperatures is crucial for the development of alcoholic beverages, but the key factors for the cold tolerance of yeast are not well known. In this report, we present the results of a screening for genes able to confer cold tolerance by overexpression in a laboratory yeast strain auxotrophic for tryptophan. We identified genes of tryptophan permeases (TAT1 and TAT2), suggesting that the first limiting factor in the growth of tryptophan auxotrophic yeast at low temperatures is tryptophan uptake. This fact is of little relevance to industrial strains which are prototrophic for tryptophan. Then, we screened for genes able to confer growth at low temperatures in tryptophan-rich media and found several genes related to phosphate uptake (PHO84, PHO87, PHO90 and GTR1). This suggests that without tryptophan limitation, uptake of inorganic phosphate becomes the limiting factor. We have found that overexpression of the previously uncharacterized ORF YCR015c/CTO1 increases the uptake of inorganic phosphate. Also, genes involved in ergosterol biosynthesis (NSG2) cause improvement of growth at 10°C, dependent on tryptophan uptake, while the gluconeogenesis gene PCK1 and the proline biosynthesis gene PRO2 cause an improvement in growth at 10°C, independent of tryptophan and phosphate uptake. PMID:25725023

  4. Radiation Component Characteristic under Consideration of Biberman Factor in Wavelength emitted from High Temperature Argon

    NASA Astrophysics Data System (ADS)

    Honda, Satoshi; Iwao, Toru; Yumoto, Motoshige; Inaba, Tsuginori

    When a reduction of the waste and dissolution of the iron are carried out by using a high temperature medium, the radiant power emitted from the medium should be suppressed. On the contrary, it is useful for lighting and treatment of hazardous wastes because it has a highly intense radiant energy. In this paper, we tried to calculate the number density and radiant power density under consideration of atmospheric high temperature pure argon (Ar) which is frequently used for a plasma arc to know the basic theory of radiant power density for the development of the plasma treatment by using radiant power. Considering kinds of particles: ArI˜ArIV and e, temperature domain: 1,000K˜30,000K and wavelength domain: 200nm˜1,000nm, and Biberman factor: changeable in wavelength, we calculated the line and continuum radiant power density as ingredients of the radiant power, and mentioned the above characteristics in every temperature, particle and wavelength range. As a result, a dominant wavelength area became ultraviolet to visibile by making Biberman factor change.

  5. Soluble sugars—Metabolism, sensing and abiotic stress

    PubMed Central

    Rosa, Mariana; Prado, Carolina; Podazza, Griselda; Interdonato, Roque; González, Juan A; Hilal, Mirna

    2009-01-01

    Plants are autotrophic and photosynthetic organisms that both produce and consume sugars. Soluble sugars are highly sensitive to environmental stresses, which act on the supply of carbohydrates from source organs to sink ones. Sucrose and hexoses both play dual functions in gene regulation as exemplified by the upregulation of growth-related genes and downregulation of stress-related genes. Although coordinately regulated by sugars, these growth- and stress-related genes are upregulated or downregulated through HXK-dependent and/or HXK-independent pathways. Sucrose-non-fermenting-1- (SNF1-) related protein pathway, analogue to the protein kinase (SNF-) yeast-signalling pathway, seems also involved in sugar sensing and transduction in plants. However, even if plants share with yeast some elements involved in sugar sensing, several aspects of sugar perception are likely to be peculiar to higher plants. In this paper, we have reviewed recent evidences how plants sense and respond to environmental factors through sugar-sensing mechanisms. However, we think that forward and reverse genetic analysis in combination with expression profiling must be continued to uncover many signalling components, and a full biochemical characterization of the signalling complexes will be required to determine specificity and cross-talk in abiotic stress signalling pathways. PMID:19816104

  6. Abiotic and Microbial Interactions during Anaerobic Transformations of Fe(II) and NOX-

    PubMed Central

    Picardal, Flynn

    2012-01-01

    Microbial Fe(II) oxidation using NO3- as the terminal electron acceptor [nitrate-dependent Fe(II) oxidation, NDFO] has been studied for over 15 years. Although there are reports of autotrophic isolates and stable enrichments, many of the bacteria capable of NDFO are known organotrophic NO3--reducers that require the presence of an organic, primary substrate, e.g., acetate, for significant amounts of Fe(II) oxidation. Although the thermodynamics of Fe(II) oxidation are favorable when coupled to either NO3- or NO2- reduction, the kinetics of abiotic Fe(II) oxidation by NO3- are relatively slow except under special conditions. NDFO is typically studied in batch cultures containing millimolar concentrations of Fe(II), NO3-, and the primary substrate. In such systems, NO2- is often observed to accumulate in culture media during Fe(II) oxidation. Compared to NO3-, abiotic reactions of biogenic NO2- and Fe(II) are relatively rapid. The kinetics and reaction pathways of Fe(II) oxidation by NO2- are strongly affected by medium composition and pH, reactant concentration, and the presence of Fe(II)-sorptive surfaces, e.g., Fe(III) oxyhydroxides and cellular surfaces. In batch cultures, the combination of abiotic and microbial Fe(II) oxidation can alter product distribution and, more importantly, results in the formation of intracellular precipitates and extracellular Fe(III) oxyhydroxide encrustations that apparently limit further cell growth and Fe(II) oxidation. Unless steps are taken to minimize or account for potential abiotic reactions, results of microbial NDFO studies can be obfuscated by artifacts of the chosen experimental conditions, the use of inappropriate analytical methods, and the resulting uncertainties about the relative importance of abiotic and microbial reactions. In this manuscript, abiotic reactions of NO3- and NO2- with aqueous Fe2+, chelated Fe(II), and solid-phase Fe(II) are reviewed along with factors that can influence overall NDFO reaction rates

  7. Interactive effects of xenobiotic, abiotic and biotic stressors on Daphnia pulex--results from a multiple stressor experiment with a fractional multifactorial design.

    PubMed

    Scherer, Christian; Seeland, Anne; Oehlmann, Jörg; Müller, Ruth

    2013-08-15

    Pollutant effects on aquatic key species are confounded by multiple abiotic and biotic stressors. To better discriminate and understand the intrinsic and environmental correlates of changing aquatic ecosystems, we untangle in present study how the effects of a low-dosed fungicide on daphnids (via different exposure routes) becomes modified by increasing temperature and the presence of a predator. Using a fractional multifactorial test design, the individual growth, reproduction and population growth rate of Daphnia pulex were investigated under exposure to the fungicide pyrimethanil at an environmental relevant concentration--either directly (via the water phase), indirectly (via food), dually (via water and food) or for multiple generations (fungicide treated source population)--at three temperatures and in presence/absence of the predator kairomones of Chaoborus flavicans. Our results clearly illustrate that multiple stress factors can modify the response of an aquatic key species to pollutants. The environmentally relevant exposure of the contaminant via food or the medium is of same importance. Nevertheless, temperature and the presence of a predator are the dominant factors controlling the reproduction of D. pulex. We conclude that sublethal pyrimethanil pollution can disturb the zooplankton community at suboptimal temperature conditions, but the effects will become masked by low temperatures or if chaoborid larvae are present. PMID:23727598

  8. Quantifying the influences of various ecological factors on land surface temperature of urban forests.

    PubMed

    Ren, Yin; Deng, Lu-Ying; Zuo, Shu-Di; Song, Xiao-Dong; Liao, Yi-Lan; Xu, Cheng-Dong; Chen, Qi; Hua, Li-Zhong; Li, Zheng-Wei

    2016-09-01

    Identifying factors that influence the land surface temperature (LST) of urban forests can help improve simulations and predictions of spatial patterns of urban cool islands. This requires a quantitative analytical method that combines spatial statistical analysis with multi-source observational data. The purpose of this study was to reveal how human activities and ecological factors jointly influence LST in clustering regions (hot or cool spots) of urban forests. Using Xiamen City, China from 1996 to 2006 as a case study, we explored the interactions between human activities and ecological factors, as well as their influences on urban forest LST. Population density was selected as a proxy for human activity. We integrated multi-source data (forest inventory, digital elevation models (DEM), population, and remote sensing imagery) to develop a database on a unified urban scale. The driving mechanism of urban forest LST was revealed through a combination of multi-source spatial data and spatial statistical analysis of clustering regions. The results showed that the main factors contributing to urban forest LST were dominant tree species and elevation. The interactions between human activity and specific ecological factors linearly or nonlinearly increased LST in urban forests. Strong interactions between elevation and dominant species were generally observed and were prevalent in either hot or cold spots areas in different years. In conclusion, quantitative studies based on spatial statistics and GeogDetector models should be conducted in urban areas to reveal interactions between human activities, ecological factors, and LST. PMID:27321883

  9. Proteomic comparison of Ralstonia solanacearum strains reveals temperature dependent virulence factors

    PubMed Central

    2014-01-01

    Background Ralstonia solanacearum, the causal agent of bacterial wilt, is a genetically diverse bacterial plant pathogen present in tropical and subtropical regions of the world that infects more than 200 plant species, including economically important solanaceous crops. Most strains of R. solanacearum are only pathogenic at temperatures between 25 to 30°C with strains that can cause disease below 20°C considered a threat to agriculture in temperate areas. Identifying key molecular factors that distinguish strains virulent at cold temperatures from ones that are not is needed to develop effective management tools for this pathogen. We compared protein profiles of two strains virulent at low temperature and two strains not virulent at low temperature when incubated in the rhizosphere of tomato seedlings at 30 and 18°C using quantitative 2D DIGE gel methods. Spot intensities were quantified and compared, and differentially expressed proteins were sequenced and identified by mass spectrometry (MS/MS). Results Four hundred and eighteen (418) differentially expressed protein spots sequenced produced 101 unique proteins. The identified proteins were classified in the Gene Ontology biological processes categories of metabolism, cell processes, stress response, transport, secretion, motility, and virulence. Identified virulence factors included catalase (KatE), exoglucanase A (ChbA), drug efflux pump, and twitching motility porin (PilQ). Other proteins identified included two components of a putative type VI secretion system. We confirmed differential expression of 13 candidate genes using real time PCR techniques. Global regulators HrpB and HrpG also had temperature dependent expression when quantified by real time PCR. Conclusions The putative involvement of the identified proteins in virulence at low temperature is discussed. The discovery of a functional type VI secretion system provides a new potential virulence mechanism to explore. The global regulators HrpG and

  10. Factors influencing the temperature sensitivity of PMMA based optical fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Webb, David J.

    2014-05-01

    The Bragg wavelength of a PMMA based fiber grating is determined by the effective core index and the grating pitch, which, in temperature sensing, depend on the thermo-optic and thermal expansion coefficients of PMMA. These two coefficients are a function of surrounding temperature and humidity. Amorphous polymers including PMMA exhibit a certain degree of anisotropic thermal expansion. The anisotropic nature of expansion mainly depends on the polymer processing history. The expansion coefficient is believed to be lower in the direction of the molecular orientation than in the direction perpendicular to the draw direction. Such anisotropic behavior of polymers can be expected in drawn PMMA based optical fiber, and will lead to a reduced thermal expansion coefficient and larger temperature sensitivity than would be the case were the fiber to be isotropic. Extensive work has been carried out to identify these factors. The temperature responses of gratings have been measured at different relative humidity. Gratings fabricated on annealed and non-annealed PMMA optical fibers are used to compare the sensitivity performance as annealing is considered to be able to mitigate the anisotropic effect in PMMA optical fiber. Furthermore an experiment has been designed to eliminate the thermal expansion contribution to the grating wavelength change, leading to increased temperature sensitivity and improved response linearity.

  11. Roots Withstanding their Environment: Exploiting Root System Architecture Responses to Abiotic Stress to Improve Crop Tolerance

    PubMed Central

    Koevoets, Iko T.; Venema, Jan Henk; Elzenga, J. Theo. M.; Testerink, Christa

    2016-01-01

    To face future challenges in crop production dictated by global climate changes, breeders and plant researchers collaborate to develop productive crops that are able to withstand a wide range of biotic and abiotic stresses. However, crop selection is often focused on shoot performance alone, as observation of root properties is more complex and asks for artificial and extensive phenotyping platforms. In addition, most root research focuses on development, while a direct link to the functionality of plasticity in root development for tolerance is often lacking. In this paper we review the currently known root system architecture (RSA) responses in Arabidopsis and a number of crop species to a range of abiotic stresses, including nutrient limitation, drought, salinity, flooding, and extreme temperatures. For each of these stresses, the key molecular and cellular mechanisms underlying the RSA response are highlighted. To explore the relevance for crop selection, we especially review and discuss studies linking root architectural responses to stress tolerance. This will provide a first step toward understanding the relevance of adaptive root development for a plant’s response to its environment. We suggest that functional evidence on the role of root plasticity will support breeders in their efforts to include root properties in their current selection pipeline for abiotic stress tolerance, aimed to improve the robustness of crops.

  12. Organ-specific proteome analysis for identification of abiotic stress response mechanism in crop

    PubMed Central

    Komatsu, Setsuko; Hossain, Zahed

    2013-01-01

    Abiotic stresses, such as flooding, drought, salinity, and high/low temperatures, are the major constraints that global crop production faces at present. Plants respond to a stress by modulating abundance of candidate proteins, either by up-regulating expression or by the synthesizing novel proteins primarily associated with plant defense system. The cellular mechanisms of stress sensing and signal transduction into cellular organelles have been reported. Nevertheless, the responses of plant cells to abiotic stresses differ in each organ. As the correlation between the expression of mRNAs and the abundance of their corresponding proteins is difficult to assess in specific organs, proteomics techniques provide one of the best options for the functional analysis of translated regions of the genome. The present review summarizes the organ-specific proteome analyses for better understanding of the response mechanisms of crops to abiotic stresses, including flooding, drought, and salinity. The differential organ-specific responses against each of these stresses are discussed in detail to provide new insights into plant stress response mechanisms at protein level. PMID:23565117

  13. The Ascorbate-glutathione-α-tocopherol Triad in Abiotic Stress Response

    PubMed Central

    Szarka, András; Tomasskovics, Bálint; Bánhegyi, Gábor

    2012-01-01

    The life of any living organism can be defined as a hurdle due to different kind of stresses. As with all living organisms, plants are exposed to various abiotic stresses, such as drought, salinity, extreme temperatures and chemical toxicity. These primary stresses are often interconnected, and lead to the overproduction of reactive oxygen species (ROS) in plants, which are highly reactive and toxic and cause damage to proteins, lipids, carbohydrates and DNA, which ultimately results in oxidative stress. Stress-induced ROS accumulation is counteracted by enzymatic antioxidant systems and non-enzymatic low molecular weight metabolites, such as ascorbate, glutathione and α-tocopherol. The above mentioned low molecular weight antioxidants are also capable of chelating metal ions, reducing thus their catalytic activity to form ROS and also scavenge them. Hence, in plant cells, this triad of low molecular weight antioxidants (ascorbate, glutathione and α-tocopherol) form an important part of abiotic stress response. In this work we are presenting a review of abiotic stress responses connected to these antioxidants. PMID:22605990

  14. The ascorbate-glutathione-α-tocopherol triad in abiotic stress response.

    PubMed

    Szarka, András; Tomasskovics, Bálint; Bánhegyi, Gábor

    2012-01-01

    The life of any living organism can be defined as a hurdle due to different kind of stresses. As with all living organisms, plants are exposed to various abiotic stresses, such as drought, salinity, extreme temperatures and chemical toxicity. These primary stresses are often interconnected, and lead to the overproduction of reactive oxygen species (ROS) in plants, which are highly reactive and toxic and cause damage to proteins, lipids, carbohydrates and DNA, which ultimately results in oxidative stress. Stress-induced ROS accumulation is counteracted by enzymatic antioxidant systems and non-enzymatic low molecular weight metabolites, such as ascorbate, glutathione and α-tocopherol. The above mentioned low molecular weight antioxidants are also capable of chelating metal ions, reducing thus their catalytic activity to form ROS and also scavenge them. Hence, in plant cells, this triad of low molecular weight antioxidants (ascorbate, glutathione and α-tocopherol) form an important part of abiotic stress response. In this work we are presenting a review of abiotic stress responses connected to these antioxidants. PMID:22605990

  15. Stress-related hormones and glycinebetaine interplay in protection of photosynthesis under abiotic stress conditions.

    PubMed

    Kurepin, Leonid V; Ivanov, Alexander G; Zaman, Mohammad; Pharis, Richard P; Allakhverdiev, Suleyman I; Hurry, Vaughan; Hüner, Norman P A

    2015-12-01

    Plants subjected to abiotic stresses such as extreme high and low temperatures, drought or salinity, often exhibit decreased vegetative growth and reduced reproductive capabilities. This is often associated with decreased photosynthesis via an increase in photoinhibition, and accompanied by rapid changes in endogenous levels of stress-related hormones such as abscisic acid (ABA), salicylic acid (SA) and ethylene. However, certain plant species and/or genotypes exhibit greater tolerance to abiotic stress because they are capable of accumulating endogenous levels of the zwitterionic osmolyte-glycinebetaine (GB). The accumulation of GB via natural production, exogenous application or genetic engineering, enhances plant osmoregulation and thus increases abiotic stress tolerance. The final steps of GB biosynthesis occur in chloroplasts where GB has been shown to play a key role in increasing the protection of soluble stromal and lumenal enzymes, lipids and proteins, of the photosynthetic apparatus. In addition, we suggest that the stress-induced GB biosynthesis pathway may well serve as an additional or alternative biochemical sink, one which consumes excess photosynthesis-generated electrons, thus protecting photosynthetic apparatus from overreduction. Glycinebetaine biosynthesis in chloroplasts is up-regulated by increases in endogenous ABA or SA levels. In this review, we propose and discuss a model describing the close interaction and synergistic physiological effects of GB and ABA in the process of cold acclimation of higher plants. PMID:25823797

  16. Determination of the Effects of Speed, Temperature, and Fuel Factors on Exhaust Emissions

    NASA Astrophysics Data System (ADS)

    Chou, Chia-Yang David

    1995-11-01

    This study provided a comprehensive approach to examining the relative significance and possible synergistic effects of speed, temperature, and fuel on mobile source emissions modeling. Eleven passenger vehicles from three fuel delivery system control groups were tested, namely, three from carburetor (CARBU), three from throttle body injection (TBI), and five from multi-port fuel injection (MPFI) group. A minimum of 90 tests were conducted on each vehicle with a random combination of three fuel types (Phase 1, Phase 2, and Indolene), three temperatures (50 F, 75 F, and 100 F), and ten speed cycles. Each vehicle was repeated for ten speed cycles (75 F and Indolene). In general, exhaust emissions descended in the order of CARBU, TBI, and MPFI. All vehicles in the CARBU group contained a "dead" catalyst, which probably explained why vehicles in CARBU were "high emitters.". Results from the paired t-test indicated that exhaust emissions difference between Phase 1 and Phase 2 fuels for all vehicles was significant. The net exhaust emissions reduction of Phase 2 over Phase 1 fuel for HC and NOx was 21% and 12%, respectively; which is in good agreements with the CARB projected 17% HC (including evaporative and exhaust emissions) and 11% CO emissions reduction based on 1996 calendar year when Phase 2 fuel is introduced. Temperature had minimal effects on exhaust emissions especially the test cycles were in hot-stabilized mode. Nevertheless, exhaust emissions from cold-start mode were higher than hot-start mode because the catalyst had not reached to optimal operating temperature during the cold-start mode. The relative contributions of speed, temperature, and fuel to exhaust emissions were determined using analysis of variance (ANOVA) and it was found interaction terms among fuel, speed, and temperature were statistically insignificant. Individually, the temperature and fuel factor played a minor role in exhaust emission modeling. Speed and vehicle type were the two

  17. Detection of Abiotic Methane in Terrestrial Continental Hydrothermal Systems: Implications for Methane on Mars

    NASA Technical Reports Server (NTRS)

    Socki, Richard A.; Niles, Paul B.; Gibson, Everett K., Jr.; Romanek, Christopher S.; Zhang, Chuanlun L.; Bissada, Kadry K.

    2008-01-01

    The recent detection of methane in the Martian atmosphere and the possibility that its origin could be attributed to biological activity, have highlighted the importance of understanding the mechanisms of methane formation and its usefulness as a biomarker. Much debate has centered on the source of the methane in hydrothermal fluids, whether it is formed biologically by microorganisms, diagenetically through the decomposition of sedimentary organic matter, or inorganically via reduction of CO2 at high temperatures. Ongoing research has now shown that much of the methane present in sea-floor hydrothermal systems is probably formed through inorganic CO2 reduction processes at very high temperatures (greater than 400 C). Experimental results have indicated that methane might form inorganically at temperatures lower still, however these results remain controversial. Currently, methane in continental hydrothermal systems is thought to be formed mainly through the breakdown of sedimentary organic matter and carbon isotope equilibrium between CO2 and CH4 is thought to be rarely present if at all. Based on isotopic measurements of CO2 and CH4 in two continental hydrothermal systems, we suggest that carbon isotope equilibration exists at temperatures as low as 155 C. This would indicate that methane is forming through abiotic CO2 reduction at lower temperatures than previously thought and could bolster arguments for an abiotic origin of the methane detected in the martian atmosphere.

  18. Improved Tolerance to Various Abiotic Stresses in Transgenic Sweet Potato (Ipomoea batatas) Expressing Spinach Betaine Aldehyde Dehydrogenase

    PubMed Central

    Fan, Weijuan; Zhang, Min; Zhang, Hongxia; Zhang, Peng

    2012-01-01

    Abiotic stresses are critical delimiters for the increased productivity and cultivation expansion of sweet potato (Ipomoea batatas), a root crop with worldwide importance. The increased production of glycine betaine (GB) improves plant tolerance to various abiotic stresses without strong phenotypic changes, providing a feasible approach to improve stable yield production under unfavorable conditions. The gene encoding betaine aldehyde dehydrogenase (BADH) is involved in the biosynthesis of GB in plants, and the accumulation of GB by the heterologous overexpression of BADH improves abiotic stress tolerance in plants. This study is to improve sweet potato, a GB accumulator, resistant to multiple abiotic stresses by promoted GB biosynthesis. A chloroplastic BADH gene from Spinacia oleracea (SoBADH) was introduced into the sweet potato cultivar Sushu-2 via Agrobacterium-mediated transformation. The overexpression of SoBADH in the transgenic sweet potato improved tolerance to various abiotic stresses, including salt, oxidative stress, and low temperature. The increased BADH activity and GB accumulation in the transgenic plant lines under normal and multiple environmental stresses resulted in increased protection against cell damage through the maintenance of cell membrane integrity, stronger photosynthetic activity, reduced reactive oxygen species (ROS) production, and induction or activation of ROS scavenging by the increased activity of free radical-scavenging enzymes. The increased proline accumulation and systemic upregulation of many ROS-scavenging genes in stress-treated transgenic plants also indicated that GB accumulation might stimulate the ROS-scavenging system and proline biosynthesis via an integrative mechanism. This study demonstrates that the enhancement of GB biosynthesis in sweet potato is an effective and feasible approach to improve its tolerance to multiple abiotic stresses without causing phenotypic defects. This strategy for trait improvement in

  19. MICROSCALE METABOLIC, REDOX AND ABIOTIC REACTIONS IN HANFORD 300 AREA SUBSURFACE SEDIMENTS

    SciTech Connect

    Beyenal, Haluk; McLEan, Jeff; Majors, Paul; Fredrickson, Jim

    2013-11-14

    The Hanford 300 Area is a unique site due to periodic hydrologic influence of river water resulting in changes in groundwater elevation and flow direction. This area is also highly subject to uranium remobilization, the source of which is currently believed to be the region at the base of the vadose zone that is subject to period saturation due to the changes in the water levels in the Columbia River. We found that microbial processes and redox and abiotic reactions which operate at the microscale were critical to understanding factors controlling the macroscopic fate and transport of contaminants in the subsurface. The combined laboratory and field research showed how microscale conditions control uranium mobility and how biotic, abiotic and redox reactions relate to each other. Our findings extended the current knowledge to examine U(VI) reduction and immobilization using natural 300 Area communities as well as selected model organisms on redox-sensitive and redox-insensitive minerals. Using innovative techniques developed specifically to probe biogeochemical processes at the microscale, our research expanded our current understanding of the roles played by mineral surfaces, bacterial competition, and local biotic, abiotic and redox reaction rates on the reduction and immobilization of uranium.

  20. Integrated biomarker responses of an estuarine invertebrate to high abiotic stress and decreased metal contamination.

    PubMed

    Rodrigues, Aurélie Pinto; Oliva-Teles, Teresa; Mesquita, Sofia Raquel; Delerue-Matos, Cristina; Guimarães, Laura

    2014-10-01

    An integrated chemical-biological effects monitoring was performed in 2010 and 2012 in two NW Iberian estuaries under different anthropogenic pressure. One is low impacted and the other is contaminated by metals. The aim was to verify the usefulness of a multibiomarker approach, using Carcinus maenas as bioindicator species, to reflect diminishing environmental contamination and improved health status under abiotic variation. Sampling sites were assessed for metal levels in sediments and C. maenas, water abiotic factors and biomarkers (neurotoxicity, energy metabolism, biotransformation, anti-oxidant defences, oxidative damage). High inter-annual and seasonal abiotic variation was observed. Metal levels in sediments and crab tissues were markedly higher in 2010 than in 2012 in the contaminated estuary. Biomarkers indicated differences between the study sites and seasons and an improvement of effects measured in C. maenas from the polluted estuary in 2012. Integrated Biomarker Response (IBR) index depicted sites with higher stress levels whereas Principal Component Analysis (PCA) showed associations between biomarker responses and environmental variables. The multibiomarker approach and integrated assessments proved to be useful to the early diagnosis of remediation measures in impacted sites. PMID:25314018

  1. Distribution of vascular epiphytes along a tropical elevational gradient: disentangling abiotic and biotic determinants.

    PubMed

    Ding, Yi; Liu, Guangfu; Zang, Runguo; Zhang, Jian; Lu, Xinghui; Huang, Jihong

    2016-01-01

    Epiphytic vascular plants are common species in humid tropical forests. Epiphytes are influenced by abiotic and biotic variables, but little is known about the relative importance of direct and indirect effects on epiphyte distribution. We surveyed 70 transects (10 m × 50 m) along an elevation gradient (180 m-1521 m) and sampled all vascular epiphytes and trees in a typical tropical forest on Hainan Island, south China. The direct and indirect effects of abiotic factors (climatic and edaphic) and tree community characteristics on epiphytes species diversity were examined. The abundance and richness of vascular epiphytes generally showed a unimodal curve with elevation and reached maximum value at ca. 1300 m. The species composition in transects from high elevation (above 1200 m) showed a more similar assemblage. Climate explained the most variation in epiphytes species diversity followed by tree community characteristics and soil features. Overall, climate (relative humidity) and tree community characteristics (tree size represented by basal area) had the strongest direct effects on epiphyte diversity while soil variables (soil water content and available phosphorus) mainly had indirect effects. Our study suggests that air humidity is the most important abiotic while stand basal area is the most important biotic determinants of epiphyte diversity along the tropical elevational gradient. PMID:26796667

  2. Distribution of vascular epiphytes along a tropical elevational gradient: disentangling abiotic and biotic determinants

    PubMed Central

    Ding, Yi; Liu, Guangfu; Zang, Runguo; Zhang, Jian; Lu, Xinghui; Huang, Jihong

    2016-01-01

    Epiphytic vascular plants are common species in humid tropical forests. Epiphytes are influenced by abiotic and biotic variables, but little is known about the relative importance of direct and indirect effects on epiphyte distribution. We surveyed 70 transects (10 m × 50 m) along an elevation gradient (180 m–1521 m) and sampled all vascular epiphytes and trees in a typical tropical forest on Hainan Island, south China. The direct and indirect effects of abiotic factors (climatic and edaphic) and tree community characteristics on epiphytes species diversity were examined. The abundance and richness of vascular epiphytes generally showed a unimodal curve with elevation and reached maximum value at ca. 1300 m. The species composition in transects from high elevation (above 1200 m) showed a more similar assemblage. Climate explained the most variation in epiphytes species diversity followed by tree community characteristics and soil features. Overall, climate (relative humidity) and tree community characteristics (tree size represented by basal area) had the strongest direct effects on epiphyte diversity while soil variables (soil water content and available phosphorus) mainly had indirect effects. Our study suggests that air humidity is the most important abiotic while stand basal area is the most important biotic determinants of epiphyte diversity along the tropical elevational gradient. PMID:26796667

  3. Polyamines and abiotic stress in plants: a complex relationship.

    PubMed

    Minocha, Rakesh; Majumdar, Rajtilak; Minocha, Subhash C

    2014-01-01

    The physiological relationship between abiotic stress in plants and polyamines was reported more than 40 years ago. Ever since there has been a debate as to whether increased polyamines protect plants against abiotic stress (e.g., due to their ability to deal with oxidative radicals) or cause damage to them (perhaps due to hydrogen peroxide produced by their catabolism). The observation that cellular polyamines are typically elevated in plants under both short-term as well as long-term abiotic stress conditions is consistent with the possibility of their dual effects, i.e., being protectors from as well as perpetrators of stress damage to the cells. The observed increase in tolerance of plants to abiotic stress when their cellular contents are elevated by either exogenous treatment with polyamines or through genetic engineering with genes encoding polyamine biosynthetic enzymes is indicative of a protective role for them. However, through their catabolic production of hydrogen peroxide and acrolein, both strong oxidizers, they can potentially be the cause of cellular harm during stress. In fact, somewhat enigmatic but strong positive relationship between abiotic stress and foliar polyamines has been proposed as a potential biochemical marker of persistent environmental stress in forest trees in which phenotypic symptoms of stress are not yet visible. Such markers may help forewarn forest managers to undertake amelioration strategies before the appearance of visual symptoms of stress and damage at which stage it is often too late for implementing strategies for stress remediation and reversal of damage. This review provides a comprehensive and critical evaluation of the published literature on interactions between abiotic stress and polyamines in plants, and examines the experimental strategies used to understand the functional significance of this relationship with the aim of improving plant productivity, especially under conditions of abiotic stress. PMID:24847338

  4. Polyamines and abiotic stress in plants: a complex relationship1

    PubMed Central

    Minocha, Rakesh; Majumdar, Rajtilak; Minocha, Subhash C.

    2014-01-01

    The physiological relationship between abiotic stress in plants and polyamines was reported more than 40 years ago. Ever since there has been a debate as to whether increased polyamines protect plants against abiotic stress (e.g., due to their ability to deal with oxidative radicals) or cause damage to them (perhaps due to hydrogen peroxide produced by their catabolism). The observation that cellular polyamines are typically elevated in plants under both short-term as well as long-term abiotic stress conditions is consistent with the possibility of their dual effects, i.e., being protectors from as well as perpetrators of stress damage to the cells. The observed increase in tolerance of plants to abiotic stress when their cellular contents are elevated by either exogenous treatment with polyamines or through genetic engineering with genes encoding polyamine biosynthetic enzymes is indicative of a protective role for them. However, through their catabolic production of hydrogen peroxide and acrolein, both strong oxidizers, they can potentially be the cause of cellular harm during stress. In fact, somewhat enigmatic but strong positive relationship between abiotic stress and foliar polyamines has been proposed as a potential biochemical marker of persistent environmental stress in forest trees in which phenotypic symptoms of stress are not yet visible. Such markers may help forewarn forest managers to undertake amelioration strategies before the appearance of visual symptoms of stress and damage at which stage it is often too late for implementing strategies for stress remediation and reversal of damage. This review provides a comprehensive and critical evaluation of the published literature on interactions between abiotic stress and polyamines in plants, and examines the experimental strategies used to understand the functional significance of this relationship with the aim of improving plant productivity, especially under conditions of abiotic stress. PMID:24847338

  5. Abiotic stress responses in plants: roles of calmodulin-regulated proteins

    PubMed Central

    Virdi, Amardeep S.; Singh, Supreet; Singh, Prabhjeet

    2015-01-01

    Intracellular changes in calcium ions (Ca2+) in response to different biotic and abiotic stimuli are detected by various sensor proteins in the plant cell. Calmodulin (CaM) is one of the most extensively studied Ca2+-sensing proteins and has been shown to be involved in transduction of Ca2+ signals. After interacting with Ca2+, CaM undergoes conformational change and influences the activities of a diverse range of CaM-binding proteins. A number of CaM-binding proteins have also been implicated in stress responses in plants, highlighting the central role played by CaM in adaptation to adverse environmental conditions. Stress adaptation in plants is a highly complex and multigenic response. Identification and characterization of CaM-modulated proteins in relation to different abiotic stresses could, therefore, prove to be essential for a deeper understanding of the molecular mechanisms involved in abiotic stress tolerance in plants. Various studies have revealed involvement of CaM in regulation of metal ions uptake, generation of reactive oxygen species and modulation of transcription factors such as CAMTA3, GTL1, and WRKY39. Activities of several kinases and phosphatases have also been shown to be modulated by CaM, thus providing further versatility to stress-associated signal transduction pathways. The results obtained from contemporary studies are consistent with the proposed role of CaM as an integrator of different stress signaling pathways, which allows plants to maintain homeostasis between different cellular processes. In this review, we have attempted to present the current state of understanding of the role of CaM in modulating different stress-regulated proteins and its implications in augmenting abiotic stress tolerance in plants. PMID:26528296

  6. Factor Study for the Separator Plate of Mcfc Having Uniform Stiffness at Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Wook; Kim, Jung-Hyun; Jun, Joong-Hwan

    A molten carbonate fuel cell (MCFC) is composed of several stacks of unit cells. A unit cell is composed of two electrodes and a matrix that is inserted between separator plates. Separator plates should properly contact the electrodes to reduce the electricity loss arising from contact resistance. To this end, a pressure of about 2 kgf/cm2 is usually applied on the top of the stack, which results in the separator plates being somewhat compacted. Furthermore, the stiffness of the separator plates becomes degraded at elevated temperatures due to softening of the plate materials. Therefore, a nonuniform temperature distribution across the separator plates induced by exothermic reactions of the oxidant and reactant gases leads to a non-uniform plate stiffness. This study has firstly evaluated the change in separator plate stiffness as temperature changes by applying pressure to the plates. Secondly, using the Taguchi method, several design factors that affect stiffness have been investigated to determine which has the most influence. Based on these results, a new design for the separators, which allows for uniform stiffness at elevated temperatures, has been proposed.

  7. Impurity temperature correction factors for the transmission grating spectrometer in the TJ-II stellarator

    SciTech Connect

    Arevalo, J.; McCarthy, K. J.; Carmona, J. M.; Fontdecaba, J. M.

    2010-10-15

    Impurity ion temperature and velocity profiles are obtained across plasmas in the TJ-II stellarator by performing charge-exchange recombination spectroscopy with a diagnostic neutral beam injector. For this, a tridirectional (toroidal plus two poloidal opposing views) multichannel spectroscopic diagnostic, incorporating 12-way fiber arrays, a compact f/1.8 spectrograph, and a back-illuminated CCD, permits Doppler line shifts and widths (of the C VI line at 529.05 nm) to be determined with 1-2 cm spatial resolution. For good photon counting statistics under Li-coated wall conditions, 600 {mu}m diameter fibers collect and transmit light to curved 100 {mu}m wide input slits. When calibrated with a neon pencil lamp this entrance slit width results in a non-Gaussian instrumental function that, if not handled correctly, can result in systematically underestimated impurity temperatures. Here we develop and present correction factors for this effect for a range of conditions.

  8. The role of abiotic conditions in shaping the long-term patterns of a high-elevation Argentine ant invasion

    USGS Publications Warehouse

    Krushelnycky, P.D.; Joe, S.M.; Medeiros, A.C.; Daehler, C.C.; Loope, L.L.

    2005-01-01

    Analysis of long-term patterns of invasion can reveal the importance of abiotic factors in influencing invasion dynamics, and can help predict future patterns of spread. In the case of the invasive Argentine ant (Linepithema humile), most prior studies have investigated this species' limitations in hot and dry climates. However, spatial and temporal patterns of spread involving two ant populations over the course of 30 years at a high elevation site in Hawaii suggest that cold and wet conditions have influenced both the ant's distribution and its rate of invasion. In Haleakala National Park on Maui, we found that a population invading at lower elevation is limited by increasing rainfall and presumably by associated decreasing temperatures. A second, higher elevation population has spread outward in all directions, but rates of spread in different directions appear to have been strongly influenced by differences in elevation and temperature. Patterns of foraging activity were strongly tied to soil temperatures, supporting the hypothesis that variation in temperature can influence rates of spread. Based on past patterns of spread, we predicted a total potential range that covers nearly 50% of the park and 75% of the park's subalpine habitats. We compared this rough estimate with point predictions derived from a degree-day model for Argentine ant colony reproduction, and found that the two independent predictions match closely when soil temperatures are used in the model. The cold, wet conditions that have influenced Argentine ant invasion at this site are likely to be influential at other locations in this species' current and future worldwide distribution. ?? 2005 Blackwell Publishing Ltd.

  9. Extremely high Q-factor mechanical modes in quartz bulk acoustic wave resonators at millikelvin temperature

    SciTech Connect

    Goryachev, M.; Creedon, D. L.; Ivanov, E. N.; Tobar, M. E.; Galliou, S.; Bourquin, R.

    2014-12-04

    We demonstrate that Bulk Acoustic Wave (BAW) quartz resonator cooled down to millikelvin temperatures are excellent building blocks for hybrid quantum systems with extremely long coherence times. Two overtones of the longitudinal mode at frequencies of 15.6 and 65.4 MHz demonstrate a maximum f.Q product of 7.8×10{sup 16} Hz. With this result, the Q-factor in such devices near the quantum ground state can be four orders of magnitude better than previously attained in other mechanical systems. Tested quartz resonators possess the ultra low acoustic losses crucial for electromagnetic cooling to the phonon ground state.

  10. ROS Regulation During Abiotic Stress Responses in Crop Plants

    PubMed Central

    You, Jun; Chan, Zhulong

    2015-01-01

    Abiotic stresses such as drought, cold, salt and heat cause reduction of plant growth and loss of crop yield worldwide. Reactive oxygen species (ROS) including hydrogen peroxide (H2O2), superoxide anions (O2•-), hydroxyl radical (OH•) and singlet oxygen (1O2) are by-products of physiological metabolisms, and are precisely controlled by enzymatic and non-enzymatic antioxidant defense systems. ROS are significantly accumulated under abiotic stress conditions, which cause oxidative damage and eventually resulting in cell death. Recently, ROS have been also recognized as key players in the complex signaling network of plants stress responses. The involvement of ROS in signal transduction implies that there must be coordinated function of regulation networks to maintain ROS at non-toxic levels in a delicate balancing act between ROS production, involving ROS generating enzymes and the unavoidable production of ROS during basic cellular metabolism, and ROS-scavenging pathways. Increasing evidence showed that ROS play crucial roles in abiotic stress responses of crop plants for the activation of stress-response and defense pathways. More importantly, manipulating ROS levels provides an opportunity to enhance stress tolerances of crop plants under a variety of unfavorable environmental conditions. This review presents an overview of current knowledge about homeostasis regulation of ROS in crop plants. In particular, we summarize the essential proteins that are involved in abiotic stress tolerance of crop plants through ROS regulation. Finally, the challenges toward the improvement of abiotic stress tolerance through ROS regulation in crops are discussed. PMID:26697045

  11. Incubation at room temperature may be an independent factor that induces chlamydospore production in Candida dubliniensis.

    PubMed

    Sancak, Banu; Colakoglu, Sule; Acikgoz, Ziya Cibali; Arikan, Sevtap

    2005-08-01

    Production of chlamydospores is one of the phenotypic features used to differentiate Candida albicans and Candida dubliniensis. C. albicans produces few chlamydospores on only cornmeal/rice-Tween agar at room temperature, whereas C. dubliniensis produces abundant chlamydospores at this temperature both on cornmeal agar and some other commonly used media. We tried to determine whether the room temperature is the main factor that induces chlamydospore production of C. dubliniensis, regardless of the medium used. For this purpose, 100 C. albicans and 24 C. dubliniensis isolates were tested for chlamydospore production at room temperature and at 37 degrees C on some routinely used media, including eosin-methylene blue agar (EMB), nutrient agar (NA), nutrient broth (NB), and also on an investigational medium, phenol red agar (PR). At 37 degrees C, none of the isolates produced chlamydospores on any of the tested media. At 26 degrees C, all C. dubliniensis isolates produced abundant chlamydospores and pseudohyphae after 24-48 h on all tested media. At this incubation temperature, all C. albicans isolates failed to produce chlamydospores and pseudohyphae on EMB, NA, and NB, whereas 2 of the C. albicans isolates produced a few chlamydospores on PR. We also observed that all C. dubliniensis isolates tested on EMB and PR produced rough colonies with a hyphal fringe around the colonies, whereas none of the C. albicans isolates showed this property. In conclusion, incubation at 26 degrees C may play the key role for production of abundant chlamydospores and pseudohyphae by C. dubliniensis. Comprehensive molecular studies are needed to clarify the genetic basis of this observation. Using EMB and PR may be an inexpensive, a time-saving, and a simple way of presumptive identification of C. dubliniensis based on chlamydospore formation and colony morphology. PMID:16054328

  12. Abiotic Methane in Land-Based Serpentinized Peridotites: New Discoveries and Isotope Surprises

    NASA Astrophysics Data System (ADS)

    Whiticar, M. J.; Etiope, G.

    2014-12-01

    Until 2008, abiotic methane in land-based serpentinized ultramafic rocks was documented (including gas and C- and H- isotope compositions) only at sites in Oman, Philippines, New Zealand and Turkey. Methane emanates from seeps and/or hyperalkaline water springs along faults and is associated with molecular hydrogen. These were considered to be very unusual and rare occurrences of gas. Now, methane is documented for peridotite-based springs or seeps (in ophiolites, orogenic massifs or intrusions) in US, Canada, Costa Rica, Greece, Italy, Japan, New Caledonia, Portugal, Spain and United Arab Emirates. Gas flux measurements are indicating that methane can also flux as invisible microseepages from the ground, through fractured peridotites, even far removed from seeps and springs. Methane C-isotope ratios range from -6 to -37 permil (VPDB) for dominantly abiotic methane. The more 13-C depleted values, e.g., California, are likely mixed with biotic gas (microbial and thermogenic gas). Methane H-isotope ratios cover a wide range from -118 to -333 permil (VSMOW). The combination of C- and H-isotopes clearly distinguish biotic from abiotic methane. Radiocarbon (14-C) analysis from bubbling seeps in Italian peridotites indicate that the methane is fossil (pMC <0.2), i.e., older than 50,000 years, similar to the Chimaera seeps in Turkey. So, methane observed in the hyperalkaline waters cannot be produced in the same waters because these are only a few thousands years old. The low temperatures of land-based peridotites (generally <100 °C at depths of 3-4 km) also constrain methane production. We discuss some hypotheses concerning gas generation in water vs. dry systems, i.e., in deeper, older, waters or in unsaturated rocks). We also discuss low vs. high temperatures, i.e., at the present-day low T conditions or at higher temperatures eventually occurring in the early stages of peridotite emplacement on land.

  13. Abiotic transformation of carbon tetrachloride at mineral surfaces. Final report, September 1990-September 1993

    SciTech Connect

    Kriegman-King, M.; Reinhard, M.

    1994-02-01

    The report addresses the ability of natural mineral surfaces to abiotically transform halogenated organic compounds in subsurface environments. The research focuses on carbon tetrachloride (CC14) as the halogenated organic and biotite, vermiculite, and pyrite as the mineral surfaces. The CCl4 transformation rates and products were quantified under different environmental conditions. The disappearance of CCl4 was significantly faster in the presence of mineral surfaces than in homogeneous solution. In systems containing the sheet silicates and HS-, the rate of reaction was dependent on the temperature, hydrogen sulfide ion concentration, surface concentration, and Fe(II) content in the minerals.

  14. Factors Affecting Process Temperature and Biogas Production in Small-scale Rural Biogas Digesters in Winter in Northern Vietnam.

    PubMed

    Pham, C H; Vu, C C; Sommer, S G; Bruun, S

    2014-07-01

    This study investigated the main factors influencing digester temperature and methods to reduce heat losses during the cold season in the subtropics. Four composite digesters (two insulated and two uninsulated) were buried underground to measure their internal temperature (°C) at a depth of 140 cm and 180 cm, biogas production and methane (CH4) concentration in biogas from August to February. In parallel the temperature of the air (100 cm above ground), in the slurry mixing tank and in the soil (10, 100, 140, and 180 cm depth) was measured by thermocouple. The influent amount was measured daily and the influent chemical composition was measured monthly during the whole experimental period. Seasonal variations in air temperature significantly affected the temperature in the soil, mixing tank and digester. Consequently, biogas production, which is temperature dependent, was influenced by the season. The main factors determining the internal temperature in the digesters were insulation with Styrofoam, air temperature and temperature of slurry in the mixing tank. Biogas production is low due to the cold climate conditions in winter in Northern Vietnam, but the study proved that storing slurry in the mixing tank until its temperature peak at around 14:00 h will increase the temperature in the digester and thus increase potential biogas production. Algorithms are provided linking digester temperature to the temperature of slurry in the mixing tank. PMID:25050049

  15. Factors Affecting Process Temperature and Biogas Production in Small-scale Rural Biogas Digesters in Winter in Northern Vietnam

    PubMed Central

    Pham, C. H.; Vu, C. C.; Sommer, S. G.; Bruun, S.

    2014-01-01

    This study investigated the main factors influencing digester temperature and methods to reduce heat losses during the cold season in the subtropics. Four composite digesters (two insulated and two uninsulated) were buried underground to measure their internal temperature (°C) at a depth of 140 cm and 180 cm, biogas production and methane (CH4) concentration in biogas from August to February. In parallel the temperature of the air (100 cm above ground), in the slurry mixing tank and in the soil (10, 100, 140, and 180 cm depth) was measured by thermocouple. The influent amount was measured daily and the influent chemical composition was measured monthly during the whole experimental period. Seasonal variations in air temperature significantly affected the temperature in the soil, mixing tank and digester. Consequently, biogas production, which is temperature dependent, was influenced by the season. The main factors determining the internal temperature in the digesters were insulation with Styrofoam, air temperature and temperature of slurry in the mixing tank. Biogas production is low due to the cold climate conditions in winter in Northern Vietnam, but the study proved that storing slurry in the mixing tank until its temperature peak at around 14:00 h will increase the temperature in the digester and thus increase potential biogas production. Algorithms are provided linking digester temperature to the temperature of slurry in the mixing tank. PMID:25050049

  16. Current perspectives in proteomic analysis of abiotic stress in Grapevines

    PubMed Central

    George, Iniga S.; Haynes, Paul A.

    2014-01-01

    Grapes are an important crop plant which forms the basis of a globally important industry. Grape and wine production is particularly vulnerable to environmental and climatic fluctuations, which makes it essential for us to develop a greater understanding of the molecular level responses of grape plants to various abiotic stresses. The completion of the initial grape genome sequence in 2007 has led to a significant increase in research on grapes using proteomics approaches. In this article, we discuss some of the current research on abiotic stress in grapevines, in the context of abiotic stress research in other plant species. We also highlight some of the current limitations in grapevine proteomics and identify areas with promising scope for potential future research. PMID:25538720

  17. Buildup of Abiotic Oxygen and Ozone in Atmospheres of Temperate Terrestrial Exoplanets

    NASA Astrophysics Data System (ADS)

    Kleinboehl, Armin; Willacy, Karen; Friedson, Andrew James; Swain, Mark R.

    2015-12-01

    The last two decades have seen a rapid increase in the detection and characterization of exoplanets. A focus of future missions will be on the subset of transiting, terrestrial, temperate exoplanets as they are the strongest candidates to harbor life as we know it.An important bioindicator for life as we know it is the existence of significant amounts of oxygen, and its photochemical byproduct ozone, in the exoplanet’s atmosphere. However, abiotic processes also produce oxygen and ozone, and the amount of oxygen abiotically produced in an atmosphere will largely depend on other atmospheric parameters. Constraining this parameter space will be essential to avoid ‘false positive’ detections of life, that is the interpretation of oxygen or ozone as a bioindicator despite being produced abiotically.Based on 1D radiative-convective model calculations, Wordsworth and Pierrehumbert (ApJL, 2014) recently pointed out that the formation and buildup of abiotic oxygen on water-rich planets largely depends on the amount of non-condensable gases in the atmosphere. The amount of non-condensable gases determines whether an atmosphere will develop a 'cold-trap' (similar to the tropopause on Earth) that contains most of the water in the lower atmosphere and dries out the upper atmosphere. If water vapor is a major constituent of the atmosphere, this cold-trapping is inhibited, leading to a much moister upper atmosphere. Water vapor in the upper atmosphere is photolyzed due to the availability of hard UV radiation, yielding oxygen.We use a photochemical model coupled to a 1D radiative-convective climate model to self-consistently study this effect in atmospheres with N2, CO2 and H2O as the main constituents. These are typical constituents for secondary, oxidized atmospheres, and they can exist in a wide range of ratios. We calculate the amounts of abiotically produced oxygen and ozone and determine the vertical structure of temperature and constituent mixing ratios for various

  18. Abiotic Stresses Downregulate Key Genes Involved in Nitrogen Uptake and Assimilation in Brassica juncea L.

    PubMed Central

    Goel, Parul; Singh, Anil Kumar

    2015-01-01

    Abiotic stresses such as salinity, drought and extreme temperatures affect nitrogen (N) uptake and assimilation in plants. However, little is known about the regulation of N pathway genes at transcriptional level under abiotic stress conditions in Brassica juncea. In the present work, genes encoding nitrate transporters (NRT), ammonium transporters (AMT), nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthase (GOGAT), glutamate dehydrogenase (GDH), asparagines synthetase (ASN) were cloned from Brassica juncea L. var. Varuna. The deduced protein sequences were analyzed to predict their subcellular localization, which confirmed localization of all the proteins in their respective cellular organelles. The protein sequences were also subjected to conserved domain identification, which confirmed presence of characteristic domains in all the proteins, indicating their putative functions. Moreover, expression of these genes was studied after 1h and 24h of salt (150 mM NaCl), osmotic (250 mM Mannitol), cold (4°C) and heat (42°C) stresses. Most of the genes encoding nitrate transporters and enzymes responsible for N assimilation and remobilization were found to be downregulated under abiotic stresses. The expression of BjAMT1.2, BjAMT2, BjGS1.1, BjGDH1 and BjASN2 was downregulated after 1hr, while expression of BjNRT1.1, BjNRT2.1, BjNiR1, BjAMT2, BjGDH1 and BjASN2 was downregulated after 24h of all the stress treatments. However, expression of BjNRT1.1, BjNRT1.5 and BjGDH2 was upregulated after 1h of all stress treatments, while no gene was found to be upregulated after 24h of stress treatments, commonly. These observations indicate that expression of most of the genes is adversely affected under abiotic stress conditions, particularly under prolonged stress exposure (24h), which may be one of the reasons of reduction in plant growth and development under abiotic stresses. PMID:26605918

  19. The transition from abiotic to biotic chemistry: When and where?

    NASA Astrophysics Data System (ADS)

    Bada, J. L.

    2001-12-01

    /product molecules survived long enough to be part of the reaction chain although most researchers who have advanced this scenario favor hydrothermal temperatures. Of the various reactions that have so far been proposed and investigated none have been demonstrated to be autocatalytic. In addition, the reactions are probably not unique to hydrothermal temperatures and would also occur at lower temperatures albeit at slower rates. Based on the estimated Arrhenius activation energies for the synthesis/decomposition reactions of the reactant/product molecules it is likely that they would have been more favorable at lower temperatures. This stability argument is especially important as the autocatalytic reactions advanced to the point of synthesizing informational molecules such as nucleic acids which have very short life times at elevated temperatures. Thus even "metabolic life" as it evolved into biochemistry as we know it would likely only have been feasible if the early Earth was cool. If the transition from abiotic chemistry to biochemistry on the early Earth indeed required cool temperatures, the transition could have occurred during cold, quiescent periods between large bolide impacts. The first life that arose, regardless of the process, may not have survived subsequent bolide impacts, however. Life may have originated several times before surface conditions became tranquil enough for periods sufficiently long to permit the survival and evolution of the first living entities into the first cellular organisms found in the fossil record 3.5 billion years ago. 1. C. Wills and J. L. Bada, 2000. "The Spark of Life: Darwin and the Primeval Soup" (Perseus Publishing, Cambridge MA) 291 pp.

  20. Mechanism and Influencing Factors of Iron Nuggets Forming in Rotary Hearth Furnace Process at Lower Temperature

    NASA Astrophysics Data System (ADS)

    Han, Hongliang; Duan, Dongping; Chen, Siming; Yuan, Peng

    2015-10-01

    In order to improve the efficiency of slag and iron separation, a new idea of "the separation of slag (solid state) and iron (molten state) in rotary hearth furnace process at lower temperature" is put forward. In this paper, the forming process of iron nuggets has been investigated. Based on those results, the forming mechanisms and influencing factors of iron nugget at low temperature are discussed experimentally using an electric resistance furnace simulating a rotary hearth furnace process. Results show that the reduction of iron ore, carburization of reduced iron, and the composition and quantity of slag are very important for producing iron nuggets at lower temperature. Reduction reaction of carbon-containing pellets is mainly at 1273 K and 1473 K (1000 °C and 1200 °C). When the temperature is above 1473 K (1200 °C), the metallization rate of carbon-containing pellets exceeds 93 pct, and the reduction reaction is substantially complete. Direct carburization is the main method for carburization of reduced iron. This reaction occurs above 1273 K (1000 °C), with carburization degree increasing greatly at 1473 K and 1573 K (1200 °C and 1300 °C) after particular holding times. Besides, to achieve the "slag (solid state) and iron (molten state) separation," the melting point of the slag phase should be increased. Slag (solid state) and iron (molten state) separation can be achieved below 1573 K (1300 °C), and when the holding time is 20 minutes, C/O is 0.7, basicity is less than 0.5 and a Na2CO3 level of 3 pct, the recovery rate of iron can reach 90 pct, with a proportion of iron nuggets more than 3.15 mm of nearly 90 pct. This study can provide theoretical and technical basis for iron nugget production.

  1. A Practical Methodology to Measure Unbiased Gas Chromatographic Retention Factor vs. Temperature Relationships

    PubMed Central

    Peng, Baijie; Kuo, Mei-Yi; Yang, Panhia; Hewitt, Joshua T.; Boswell, Paul G.

    2014-01-01

    Compound identification continues to be a major challenge. Gas chromatography-mass spectrometry (GC-MS) is a primary tool used for this purpose, but the GC retention information it provides is underutilized because existing retention databases are experimentally restrictive and unreliable. A methodology called “retention projection” has the potential to overcome these limitations, but it requires the retention factor (k) vs. T relationship of a compound to calculate its retention time. Direct methods of measuring k vs. T relationships from a series of isothermal runs are tedious and time-consuming. Instead, a series of temperature programs can be used to quickly measure the k vs. T relationships, but they are generally not as accurate when measured this way because they are strongly biased by non-ideal behavior of the GC system in each of the runs. In this work, we overcome that problem by using the retention times of 25 n-alkanes to back-calculate the effective temperature profile and hold-up time vs. T profiles produced in each of six temperature programs. When the profiles were measured this way and taken into account, the k vs. T relationships measured from each of two different GC-MS instruments were nearly as accurate as the ones measured isothermally, showing less than 2-fold more error. Furthermore, temperature-programmed retention times calculated in five other labs from the new k vs. T relationships had the same distribution of error as when they were calculated from k vs. T relationships measured isothermally. Free software was developed to make the methodology easy to use. The new methodology potentially provides a relatively fast and easy way to measure unbiased k vs. T relationships. PMID:25496658

  2. Mismatch in microbial food webs: predators but not prey perform better in their local biotic and abiotic conditions.

    PubMed

    Parain, Elodie C; Gravel, Dominique; Rohr, Rudolf P; Bersier, Louis-Félix; Gray, Sarah M

    2016-07-01

    Understanding how trophic levels respond to changes in abiotic and biotic conditions is key for predicting how food webs will react to environmental perturbations. Different trophic levels may respond disproportionately to change, with lower levels more likely to react faster, as they typically consist of smaller-bodied species with higher reproductive rates. This response could cause a mismatch between trophic levels, in which predators and prey will respond differently to changing abiotic or biotic conditions. This mismatch between trophic levels could result in altered top-down and bottom-up control and changes in interaction strength. To determine the possibility of a mismatch, we conducted a reciprocal-transplant experiment involving Sarracenia purpurea food webs consisting of bacterial communities as prey and a subset of six morphologically similar protozoans as predators. We used a factorial design with four temperatures, four bacteria and protozoan biogeographic origins, replicated four times. This design allowed us to determine how predator and prey dynamics were altered by abiotic (temperature) conditions and biotic (predators paired with prey from either their local or non-local biogeographic origin) conditions. We found that prey reached higher densities in warmer temperature regardless of their temperature of origin. Conversely, predators achieved higher densities in the temperature condition and with the prey from their origin. These results confirm that predators perform better in abiotic and biotic conditions of their origin while their prey do not. This mismatch between trophic levels may be especially significant under climate change, potentially disrupting ecosystem functioning by disproportionately affecting top-down and bottom-up control. PMID:27547320

  3. Abiotic constraints eclipse biotic resistance in determining invasibility along experimental vernal pool gradients.

    PubMed

    Gerhardt, Fritz; Collinge, Sharon K

    2007-04-01

    Effective management of invasive species requires that we understand the mechanisms determining community invasibility. Successful invaders must tolerate abiotic conditions and overcome resistance from native species in invaded habitats. Biotic resistance to invasions may reflect the diversity, abundance, or identity of species in a community. Few studies, however, have examined the relative importance of abiotic and biotic factors determining community invasibility. In a greenhouse experiment, we simulated the abiotic and biotic gradients typically found in vernal pools to better understand their impacts on invasibility. Specifically, we invaded plant communities differing in richness, identity, and abundance of native plants (the "plant neighborhood") and depth of inundation to measure their effects on growth, reproduction, and survival of five exotic plant species. Inundation reduced growth, reproduction, and survival of the five exotic species more than did plant neighborhood. Inundation reduced survival of three species and growth and reproduction of all five species. Neighboring plants reduced growth and reproduction of three species but generally did not affect survival. Brassica rapa, Centaurea solstitialis, and Vicia villosa all suffered high mortality due to inundation but were generally unaffected by neighboring plants. In contrast, Hordeum marinum and Lolium multiflorum, whose survival was unaffected by inundation, were more impacted by neighboring plants. However, the four measures describing plant neighborhood differed in their effects. Neighbor abundance impacted growth and reproduction more than did neighbor richness or identity, with growth and reproduction generally decreasing with increasing density and mass of neighbors. Collectively, these results suggest that abiotic constraints play the dominant role in determining invasibility along vernal pool and similar gradients. By reducing survival, abiotic constraints allow only species with the

  4. Deep level observation in InP by temperature dependence of the van der Pauw`s symmetry factor

    SciTech Connect

    Somogyi, K.

    1996-12-31

    One of the most convenient methods of the basic characterization of the semiconductors is the Hall effect measurement by van der Pauw`s geometry. As a by-product, the symmetry factor and a function of the symmetry factor is calculated. It is supposed that temperature dependent changes in the value of the symmetry factor indicate inhomogeneities of the sample, since this factor describes an electrical symmetry of the sample, not simply a geometrical one. Otherwise this factor is not assumed as an important information. In this work the author wishes to demonstrate that this factor can indicate quite important properties of the sample.

  5. Environmental factors affecting the low temperature isomerization of homohopanes in acidic peat deposits, central China

    NASA Astrophysics Data System (ADS)

    Huang, Xianyu; Meyers, Philip A.; Xue, Jiantao; Gong, Linfeng; Wang, Xinxin; Xie, Shucheng

    2015-04-01

    Progressively more evidence reveals the abundant occurrence of the C31 homohopane with a 17α, 21β-configuration (C31 αβ) in immature peats. This compound is commonly considered to be an indicator of thermal maturity in petroleum source rocks, but in peats it has also been interpreted to reflect the oxidation and subsequent decarboxylation reactions of bacteriohopanepolyols with microbially mediated epimerization at C-17 that is catalyzed by the acidic peat conditions. To learn more about the environmental factors that affect the low-temperature isomerization of homohopanes, we investigated the distribution patterns of homohopanes in a well-studied peat core from the Dajiuhu peatland, central China, together with data from modern surface peat samples from Dajiuhu and three other locations. From comparison with paleotemperature and paleohydrologic records in the peat core, we hypothesize that the ratio of C31 αβ hopane relative to the ββ isomer (C31 αβ/ββ) is mainly influenced on a centennial to millennial timescale by ambient temperature with a secondary effect from redox conditions that are defined by peatland water levels. The surface peat samples revealed that relatively high C31 αβ/ββ values occurred under pH < 6. These results suggest that pH is indeed an important factor in the low-temperature isomerization of C31 homohopanes, although the magnitude of the pH effect may be less than those of ambient temperature and redox conditions. In both surface peat and peat horizons from the Dajiuhu peatland, the amount of the C31 αβ compound with R configuration relative to that with S configuration (C31 R/S) varied closely with C31 αβ/ββ, suggesting that the epimerization at both C-17 and C-22 may happen synchronously and at similar rates. This study reveals that the isomerization of homohopanes has the potential to reflect paleoenvironmental changes in acidic peat deposits. In addition, acidic peat samples investigated in this and previous studies

  6. Abiotic controls on H{sub 2} production from basalt-water reactions and implications for aquifer biogeochemistry

    SciTech Connect

    Stevens, T.O.; McKinley, J.P.

    2000-03-01

    Abiotic production of H{sub 2} from basalt reactions in aqueous solutions is hypothesized to support microbial ecosystems in deep subsurface aquifers, such as those found in the Columbia River Basalt group (CRB). The authors investigated factors controlling this phenomenon, including rock composition, pH, temperature, sterilization method, reducing agents, and product removal. Ferrous silicate minerals were found to be the basalt components responsible for H{sub 2} production from anaerobic water-rock interactions. H{sub 2} evolution was faster at pH < 7 but occurred from pH 5 to pH 11, which covers the pH range (7--10) measured in CRB groundwaters. The onset of H{sub 2} evolution coincided with the appearance of dissolved Fe{sup 2+}, and an apparent alkaline inhibition could be alleviated by the addition of excess FeCl{sub 2}. This may reflect, in part, the low redox conditions needed for H{sub 2} evolution and suggests that H{sub 2} may be controlled by reaction rates of ferrous silicate minerals. Rates were higher at 60 C than at 30 C, suggesting that the geothermal gradient may lead to increased H{sub 2} production at depth. The results were consistent with the hypothesis at depth. The results were consistent with the hypothesis that basalt-redox reactions support primary production by microorganisms in some terrestrial subsurface environments.

  7. Low temperature resistivity, thermoelectricity, and power factor of Nb doped anatase TiO2

    NASA Astrophysics Data System (ADS)

    Jaćimović, J.; Gaál, R.; Magrez, A.; Piatek, J.; Forró, L.; Nakao, S.; Hirose, Y.; Hasegawa, T.

    2013-01-01

    The resistivity of a very high quality anatase TiO2 doped with 6% of Nb was measured from 300 K down to 40 mK. No sign of superconductivity was detected. Instead, a minute quantity of cation vacancies resulted in a Kondo scattering. Measurements of thermo-electric power and resistivity were extended up to 600 K. The calculated power factor has a peak value of 14 μW/(K2cm) at 350 K, which is comparable to that of Bi2Te3 [Venkatasubramanian et al., Nature 413, 597 (2001)], the archetype thermolectrics. Taking the literature value for the thermal conductivity of Nb doped TiO2 thin films, the calculated figure of merit (ZT) is in the range of 0.1 above 300 K. This value is encouraging for further engineering of the material in order to reach ZT of 1 suitable for high temperature thermoelectrics.

  8. ABIOTIC DEGRADATION OF TRICHLOROETHYLENE UNDER THERMAL REMEDIATION CONDITIONS

    EPA Science Inventory

    The degradation of TCE (C2HCl3) to carbon dioxide (CO2) and chloride (Cl-) has been reported to occur during thermal remediation of subsurface environments. The overall goal of this study was to evaluate abiotic degradation of TCE at el...

  9. ABIOTIC REDUCTION OF NITRO AROMATIC PESTICIDES IN ANAEROBIC LABORATORY SYSTEMS

    EPA Science Inventory

    Rapid abiotic reduction of nitro aromatic pesticides occurs in homogeneous solutions of quinone redox couples, which were selected to model the redox-labile functianal groups in natural organic matter. he kinetics of methyl parathion disappearance are first order in methyl parath...

  10. Adaptation of Extremophilic Proteins with Temperature and Pressure: Evidence from Initiation Factor 6.

    PubMed

    Calligari, Paolo A; Calandrini, Vania; Ollivier, Jacques; Artero, Jean-Baptiste; Härtlein, Michael; Johnson, Mark; Kneller, Gerald R

    2015-06-25

    In this work, we study dynamical properties of an extremophilic protein, Initiation Factor 6 (IF6), produced by the archeabacterium Methanocaldococcus jannascii, which thrives close to deep-sea hydrothermal vents where temperatures reach 80 °C and the pressure is up to 750 bar. Molecular dynamics simulations (MD) and quasi-elastic neutron scattering (QENS) measurements give new insights into the dynamical properties of this protein with respect to its eukaryotic and mesophilic homologue. Results obtained by MD are supported by QENS data and are interpreted within the framework of a fractional Brownian dynamics model for the characterization of protein relaxation dynamics. IF6 from M. jannaschii at high temperature and pressure shares similar flexibility with its eukaryotic homologue from S. cerevisieae under ambient conditions. This work shows for the first time, to our knowledge, that the very common pattern of corresponding states for thermophilic protein adaptation can be extended to thermo-barophilic proteins. A detailed analysis of dynamic properties and of local structural fluctuations reveals a complex pattern for "corresponding" structural flexibilities. In particular, in the case of IF6, the latter seems to be strongly related to the entropic contribution given by an additional, C-terminal, 20 amino-acid tail which is evolutionary conserved in all mesophilic IF6s. PMID:25996652

  11. Genetic Diversity In Abiotic Stress Tolerances Among Wheat Species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Landraces and close related species of hexaploid wheat (Triticum aestivum L.) offer a vast reservoir of genetic resources for wheat improvement to production on abiotic stressed soils. In order to utilize the wheat landrace and close relative gene pools, the evaluation of wheat landrace and close r...

  12. Are karrikins involved in plant abiotic stress responses?

    PubMed

    Li, Weiqiang; Tran, Lam-Son Phan

    2015-09-01

    Recent reports have shown that strigolactones play a positive role in plant responses to drought and salt stress through MAX2 (More Axillary Growth 2). Increasing evidence suggests that MAX2 is also involved in karrikin signaling, raising the question whether karrikins play any role in plant adaptation to abiotic stresses. PMID:26255855

  13. ABIOTIC TRANSFORMATION PATHWAYS OF ORGANIC CHEMICALS IN AQUATIC ECOSYSTEMS

    EPA Science Inventory

    Information is presented for assessing the potential of an organic chemical to undergo abiotic transformation in aquatic ecosystems. hen predicting the environmental fate of an organic chemical, two primary questions must be addressed. irst, what are the reaction kinetics for the...

  14. Daily and Interannual Variability of Air Temperature and Precipitation As Agricultural Factor

    NASA Astrophysics Data System (ADS)

    Sourkova, G.; Pona, C.

    The problem investigated concerns wheat growing process sensitivity to the changes in climate variability. For the sensitivity analysis five CERES-model runs are held for three stations in Italy: Decimomannu (Sardinia), Brindisi (Apulia) and Ghedi (Padana valley, Veneto). The only difference between these five experiments for each station is a weather input. All five weather inputs for each location are simulated by weather generator WXGEN. First run ("base") is forced by weather input having tempera- ture and precipitation variance equal to the present-day values (1960-1990). Then two crop simulations are made with changed "base" interannual variance of monthly to- tal precipitation by multiplicative factors 0.5 and 2. Temperature variability remains unchanged. Last two model runs are carried out with daily halved and doubled temper- ature variance, precipitation variability is the same as in "base" simulation. Investiga- tion showed that doubled precipitation variability is accompanied at all three locations by the largest amounts of yield variability for all five scenarios. Decreased precipi- tation variability is followed by yield decline and, at the same time the amplitude of yield change is the least compared with other forcings. Decreasing of precipitation variability results in noticeably raised harvest index for the years of minimum yield. For Decimomannu and Brindisi it is almost equal to that of the maximum yield years. In general, more significantly expressed response of the yield amounts occurs for pre- cipitation variability forcings. The influence of temperature variability changes seems to be less for all three locations.

  15. Weighing Abiotic and Biotic Influences on Weed Seed Predation Rates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weed seed predation is an important ecosystem service supporting weed management in low-external-input agroecosystems. Current knowledge of weed seed predation focuses on biotic mechanisms, with less understood about the relative impact of abiotic variables. In order to quantify relative contributio...

  16. Weighing Abiotic and Biotic Influences on Weed Seed Predation Rates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weed seed predation is an important ecosystem service supporting weed management in low-external-input agroecosystems. Current knowledge of weed seed predation in arable systems focuses on biotic mechanisms, with less understood about the relative impact of abiotic variables on this process. In orde...

  17. Genetic mapping of abiotic stress responses in sorghum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Due to rich genetic diversity for tolerance to various abiotic stress conditions, sorghum is an ideal system for genetic mapping and elucidation of genome regions that confer such response among cereal crops. Coupled with the development of DNA marker technologies and most recently the sequencing o...

  18. The abiotic and biotic drivers of rapid diversification in Andean bellflowers (Campanulaceae).

    PubMed

    Lagomarsino, Laura P; Condamine, Fabien L; Antonelli, Alexandre; Mulch, Andreas; Davis, Charles C

    2016-06-01

    The tropical Andes of South America, the world's richest biodiversity hotspot, are home to many rapid radiations. While geological, climatic, and ecological processes collectively explain such radiations, their relative contributions are seldom examined within a single clade. We explore the contribution of these factors by applying a series of diversification models that incorporate mountain building, climate change, and trait evolution to the first dated phylogeny of Andean bellflowers (Campanulaceae: Lobelioideae). Our framework is novel for its direct incorporation of geological data on Andean uplift into a macroevolutionary model. We show that speciation and extinction are differentially influenced by abiotic factors: speciation rates rose concurrently with Andean elevation, while extinction rates decreased during global cooling. Pollination syndrome and fruit type, both biotic traits known to facilitate mutualisms, played an additional role in driving diversification. These abiotic and biotic factors resulted in one of the fastest radiations reported to date: the centropogonids, whose 550 species arose in the last 5 million yr. Our study represents a significant advance in our understanding of plant evolution in Andean cloud forests. It further highlights the power of combining phylogenetic and Earth science models to explore the interplay of geology, climate, and ecology in generating the world's biodiversity. PMID:26990796

  19. Surface temperature-controlling factors during transaction of Mexican monsoon in the Sonoran Desert, North-West Mexico

    NASA Astrophysics Data System (ADS)

    Tereshchenko, I.; Zolotokrilin, A.; Titkova, T.; Brito, L.; Monzon, C.

    2009-12-01

    Correlation between albedo and dry land surface temperature can serve as an indicator of processes, which control the temperature. The term dry land is used in reference to arid, semi-arid and dry subhumid regions, whose humidification coefficient ranges between 0.05 and 0.65 according to United Nations Convention to combat desertification in those countries experiencing serious drought and desertification, particularly in Africa. Geneva, 1994. The three main competing factors of underlying surface temperature control are an inherent feature of dry lands: first - radiation, second - evapotranspiration, third - aerodynamic control. This study is focused on seasonal cycle of parameters, which control surface temperature in the Sonora desert (North-West Mexico). The understanding of this process is important for monitoring of desertification. This is so because in a certain year, the time span of the period, during which the radiation factor is predominant, is an important factor in the desertification process. One indirect characteristic of prevalence of the radiation factor is Normalized Difference Vegetation Index (NDVI), which is an indicator of green phytomass. The main features of the ratio between albedo and surface temperature are discussed in terms of analysis of monthly means (albedo, temperature, NDVI) in the state of Sonora (29-32N, 111-115W), in particular, within the box 30-31N, 112-113W. The analysis of synchronous time series of albedo, surface temperature and NDVI has shown that the dominating temperature-controlling factors can switch within the year in the study area. The radiation factor is dominant in dry months (April - May) and the surface temperature is negatively correlated with albedo. This can cause generation of positive albedo-precipitation feedback, which in turn contributes to the desertification process.

  20. Transcriptome Analysis Reveals Crosstalk of Responsive Genes to Multiple Abiotic Stresses in Cotton (Gossypium hirsutum L.)

    PubMed Central

    Zhu, Ya-Na; Shi, Dong-Qiao; Ruan, Meng-Bin; Zhang, Li-Li; Meng, Zhao-Hong; Liu, Jie; Yang, Wei-Cai

    2013-01-01

    Abiotic stress is a major environmental factor that limits cotton growth and yield, moreover, this problem has become more and more serious recently, as multiple stresses often occur simultaneously due to the global climate change and environmental pollution. In this study, we sought to identify genes involved in diverse stresses including abscisic acid (ABA), cold, drought, salinity and alkalinity by comparative microarray analysis. Our result showed that 5790, 3067, 5608, 778 and 6148 transcripts, were differentially expressed in cotton seedlings under treatment of ABA (1μM ABA), cold (4°C), drought (200mM mannitol), salinity (200mM NaCl) and alkalinity (pH=11) respectively. Among the induced or suppressed genes, 126 transcripts were shared by all of the five kinds of abiotic stresses, with 64 up-regulated and 62 down-regulated. These common members are grouped as stress signal transduction, transcription factors (TFs), stress response/defense proteins, metabolism, transport facilitation, as well as cell wall/structure, according to the function annotation. We also noticed that large proportion of significant differentially expressed genes specifically regulated in response to different stress. Nine of the common transcripts of multiple stresses were selected for further validation with quantitative real time RT-PCR (qRT-PCR). Furthermore, several well characterized TF families, for example, WRKY, MYB, NAC, AP2/ERF and zinc finger were shown to be involved in different stresses. As an original report using comparative microarray to analyze transcriptome of cotton under five abiotic stresses, valuable information about functional genes and related pathways of anti-stress, and/or stress tolerance in cotton seedlings was unveiled in our result. Besides this, some important common factors were focused for detailed identification and characterization. According to our analysis, it suggested that there was crosstalk of responsive genes or pathways to multiple abiotic

  1. TRANSFORMATIONS OF HALOGENATED ALIPHATIC COMPOUNDS: OXIDATION, REDUCTION, SUBSTITUTION, AND DEHYDROHALOGENATION REACTIONS OCCUR ABIOTICALLY OR IN MICROBIAL AND MAMMALIAN SYSTEMS

    EPA Science Inventory

    The current understanding of abiotic and biotic chemistry of halogenated aliphatic compounds is systematized and summarized. Knowledge of abiotic transformations can provide a conceptual framework for understanding biologically mediated transformations. Most abiotic transformatio...

  2. Influence of abiotic stress, flower morphology, and pollen dehydration sensitivity on cotton out-crossing potential

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genetic diversity in reproductive abiotic stress tolerance has been reported for cotton [Gossypium hirsutum (L.)] based upon the percentage of anther dehiscence of mature pollen in adverse environments. This study investigated the abiotic stress tolerance of mature pollen and identified ...

  3. Abiotic Condensation Synthesis of Glyceride Lipids and Wax Esters Under Simulated Hydrothermal Conditions

    NASA Astrophysics Data System (ADS)

    Rushdi, Ahmed I.; Simoneit, Bernd R. T.

    2006-04-01

    Precursor compounds for abiotic proto cellular membranes are necessary for the origin of life. Amphipathic compounds such as fatty acids and acyl glycerols are important candidates for micelle/bilayer/vesicle formation. Two sets of experiments were conducted to study dehydration reactions of model lipid precursors in aqueous media to form acyl polyols and wax esters, and to evaluate the stability and reactions of the products at elevated temperatures. In the first set, mixtures of n-nonadecanoic acid and ethylene glycol in water, with and without oxalic acid, were heated at discrete temperatures from 150 ∘C to 300 ∘C for 72 h. The products were typically alkyl alkanoates, ethylene glycolyl alkanoates, ethylene glycolyl bis-alkanoates and alkanols. The condensation products had maximum yields between 150 ∘C and 250 ∘C, and were detectable and thus stable under hydrothermal conditions to temperatures < 300 ∘C. In the second set of experiments, mixtures of n-heptanoic acid and glycerol were heated using the same experimental conditions, with and without oxalic acid, between 100 ∘C and 250 ∘C. The main condensation products were two isomers each of monoacylglycerols and diacylglycerols at all temperatures, as well as minor amounts of the fatty acid anhydride and methyl ester. The yield of glyceryl monoheptanoates generally increased with increasing temperature and glyceryl diheptanoates decreased noticeably with increasing temperature. The results indicate that condensation reactions and abiotic synthesis of organic lipid compounds under hydrothermal conditions occur easily, provided precursor concentrations are sufficiently high.

  4. Abiotic ozone and oxygen in atmospheres similar to prebiotic Earth

    SciTech Connect

    Domagal-Goldman, Shawn D.; Segura, Antígona; Claire, Mark W.; Robinson, Tyler D.; Meadows, Victoria S.

    2014-09-10

    The search for life on planets outside our solar system will use spectroscopic identification of atmospheric biosignatures. The most robust remotely detectable potential biosignature is considered to be the detection of oxygen (O{sub 2}) or ozone (O{sub 3}) simultaneous to methane (CH{sub 4}) at levels indicating fluxes from the planetary surface in excess of those that could be produced abiotically. Here we use an altitude-dependent photochemical model with the enhanced lower boundary conditions necessary to carefully explore abiotic O{sub 2} and O{sub 3} production on lifeless planets with a wide variety of volcanic gas fluxes and stellar energy distributions. On some of these worlds, we predict limited O{sub 2} and O{sub 3} buildup, caused by fast chemical production of these gases. This results in detectable abiotic O{sub 3} and CH{sub 4} features in the UV-visible, but no detectable abiotic O{sub 2} features. Thus, simultaneous detection of O{sub 3} and CH{sub 4} by a UV-visible mission is not a strong biosignature without proper contextual information. Discrimination between biological and abiotic sources of O{sub 2} and O{sub 3} is possible through analysis of the stellar and atmospheric context—particularly redox state and O atom inventory—of the planet in question. Specifically, understanding the spectral characteristics of the star and obtaining a broad wavelength range for planetary spectra should allow more robust identification of false positives for life. This highlights the importance of wide spectral coverage for future exoplanet characterization missions. Specifically, discrimination between true and false positives may require spectral observations that extend into infrared wavelengths and provide contextual information on the planet's atmospheric chemistry.

  5. Stable carbon isotope analysis to distinguish biotic and abiotic degradation of 1,1,1-trichloroethane in groundwater sediments.

    PubMed

    Broholm, Mette M; Hunkeler, Daniel; Tuxen, Nina; Jeannottat, Simon; Scheutz, Charlotte

    2014-08-01

    The fate and treatability of 1,1,1-TCA by natural and enhanced reductive dechlorination was studied in laboratory microcosms. The study shows that compound-specific isotope analysis (CSIA) identified an alternative 1,1,1-TCA degradation pathway that cannot be explained by assuming biotic reductive dechlorination. In all biotic microcosms 1,1,1-TCA was degraded with no apparent increase in the biotic degradation product 1,1-DCA. 1,1,1-TCA degradation was documented by a clear enrichment in (13)C in all biotic microcosms, but not in the abiotic control, which suggests biotic or biotically mediated degradation. Biotic degradation by reductive dechlorination of 1,1-DCA to CA only occurred in bioaugmented microcosms and in donor stimulated microcosms with low initial 1,1,1-TCA or after significant decrease in 1,1,1-TCA concentration (after∼day 200). Hence, the primary degradation pathway for 1,1,1-TCA does not appear to be reductive dechlorination via 1,1-DCA. In the biotic microcosms, the degradation of 1,1,1-TCA occurred under iron and sulfate reducing conditions. Biotic reduction of iron and sulfate likely resulted in formation of FeS, which can abiotically degrade 1,1,1-TCA. Hence, abiotic degradation of 1,1,1-TCA mediated by biotic FeS formation constitute an explanation for the observed 1,1,1-TCA degradation. This is supported by a high 1,1,1-TCA (13)C enrichment factor consistent with abiotic degradation in biotic microcosms. 1,1-DCA carbon isotope field data suggest that this abiotic degradation of 1,1,1-TCA is a relevant process also at the field site. PMID:24559936

  6. Adsorbate migration effects on continuous and discontinuous temperature-dependent transitions in the quality factors of graphene nanoresonators.

    PubMed

    Jiang, Jin-Wu; Wang, Bing-Shen; Park, Harold S; Rabczuk, Timon

    2014-01-17

    We perform classical molecular dynamics simulation to investigate the mechanisms underpinning the unresolved, experimentally observed temperature-dependent scaling transition in the quality factors of graphene nanomechanical resonators (GNMRs). Our simulations reveal that the mechanism underlying this temperature scaling phenomenon is the out-of-plane migration of adsorbates on GNMRs. Specifically, the migrating adsorbate undergoes frequent collisions with the GNMR, which strongly influences the resulting mechanical oscillation, and thus the quality factors. We also predict a discontinuous transition in the quality factor at a lower critical temperature, which results from the in-plane migration of the adsorbate. Overall, our work clearly demonstrates the strong effect of adsorbate migration on the quality factors of GNMRs. PMID:24334407

  7. Abiotic Versus Biotic Pathogens: Replicative Growth in Host Tissues Key to Discriminating Between Biotoxic Injury and Active Pathogenesis

    NASA Technical Reports Server (NTRS)

    Schuerger, Andrew C.; Ming, Douglas W.; Golden, D. C.

    2012-01-01

    Life can be defined as a self-sustaining chemical system capable of undergoing Darwinian evolution; a self-bounded, self-replicating, and self-perpetuating entity [1]. This definition should hold for terrestrial as well as extraterrestrial life-forms. Although, it is reasonable to expect that a Mars life-form would be more adaptable to Mars-like conditions than to Earth-like environments, it remains possible that negative ecological or host interactions might occur if Mars microbiota were to be inadvertently released into the terrestrial environment. A biogenic infectious agent can be defined as a self-sustaining chemical system capable of undergoing Darwinian evolution and derives its sustenance from a living cell or from the by-products of cell death. Disease can be de-fined as the detrimental alteration of one or more ordered metabolic processes in a living host caused by the continued irritation of a primary causal factor or factors; disease is a dynamic process [2]. In contrast, an injury is due to an instantaneous event; injury is not a dynamic process [2]. A causal agent of disease is defined as a pathogen, and can be either abiotic or biotic in nature. Diseases incited by biotic pathogens are the exceptions, not the norms, in terrestrial host-microbe interactions. Disease induction in a plant host can be conceptually characterized using the Disease Triangle (Fig. 1) in which disease occurs only when all host, pathogen, and environ-mental factors that contribute to the development of disease are within conducive ranges for a necessary minimum period of time. For example, plant infection and disease caused by the wheat leaf rust fungus, Puccinia recondita, occur only if virulent spores adhere to genetically susceptible host tissues for at least 4-6 hours under favorable conditions of temperature and moisture [3]. As long as one or more conditions required for disease initiation are not available, disease symptoms will not develop.

  8. Using thermodynamics to assess biotic and abiotic impediments to root water uptake

    NASA Astrophysics Data System (ADS)

    Bechmann, Marcel; Hildebrandt, Anke; Kleidon, Axel

    2016-04-01

    Root water uptake has been the subject of extensive research, dealing with understanding the processes limiting transpiration and understanding strategies of plants to avoid water stress. Many of those studies use models of water flow from the soil through the plant into the atmosphere to learn about biotic and abiotic factors affecting plant water relations. One important question in this context is to identify those processes that are most limiting to water transport, and specifically whether these processes lie within the plant or the soil? Here, we propose to use a thermodynamic formulation of root water uptake to answer this question. The method allows us to separate the energy exported at the root collar into a sum of energy fluxes related to all processes along the flow path, notably including the effect of increasing water retention in drier soils. Evaluation of the several contributions allows us to identify and rank the processes by how much these impede water flow from the soil to the atmosphere. The application of this approach to a complex 3-dimensional root water uptake model reveals insights on the role of root versus soil resistances to limit water flow. We investigate the efficiency of root water uptake in an ensemble of root systems with varying root hydraulic properties. While root morphology is kept the same, root radial and axial resistances are artificially varied. Starting with entirely young systems (uptake roots, high radial, low axial conductance) we increasingly add older roots (transport roots, high axial, low radial conductance) to improve transport within root systems. This yields a range of root hydraulic architectures, where the extremes are limited either by radial uptake capacity or low capacity to transport water along the root system. We model root water uptake in this range of root systems with a 3-dimensional root water uptake model in two different soils, applying constant flux boundary conditions in a dry down experiment and

  9. Abiotic Nitrous Oxide Production in Natural and Artificial Seawater

    NASA Astrophysics Data System (ADS)

    Ochoa, H.; Stanton, C. L.; Cavazos, A. R.; Ostrom, N. E.; Glass, J. B.

    2014-12-01

    The ocean contributes approximately one third of global sources of nitrous oxide (N2O) to the atmosphere. While nitrification is thought to be the dominant pathway for marine N2O production, mechanisms remain unresolved. Previous studies have carried the implicit assumption that marine N2O originates directly from enzymatic sources. However, abiotic production of N2O is possible via chemical reactions between nitrogenous intermediates and redox active trace metals in seawater. In this study, we investigated N2O production and isotopic composition in treatments with and without added hydroxylamine (NH2OH) and nitric oxide (NO), intermediates in microbial oxidation of ammonia to nitrite, and Fe(III). Addition of substrates to sterile artificial seawater was compared with filtered and unfiltered seawater from Sapelo Island, coastal Georgia, USA. N2O production was observed immediately after addition of Fe(III) in the presence of NH2OH at pH 8 in sterile artificial seawater. Highest N2O production was observed in the presence of Fe(III), NO, and NH2OH. The isotopomer site preference of abiotically produced N2O was consistent with previous studies (31 ± 2 ‰). Higher abiotic N2O production was observed in sterile artificial seawater (salinity: 35 ppt) than filtered Sapelo Island seawater (salinity: 25 ppt) whereas diluted sterile artificial seawater (18 ppt) showed lowest N2O production, suggesting that higher salinity promotes enhanced abiotic N2O production. Addition of Fe(III) to unfiltered Sapelo Island seawater stimulated N2O production. The presence of ammonia-oxidizing archaea (AOA), which lack known N2O producing enzymes, in Sapelo Island seawater was confirmed by successful amplification of the archaeal amoA gene, whereas ammonia-oxidizing bacteria (AOB), which contain N2O-producing enzymes were undetected. Given the few Fe-containing proteins present in AOA, it is likely that Fe(III) addition promoted N2O production via an abiotic vs. enzymatic N2O mechanism

  10. Molecular genetic perspectives on cross-talk and specificity in abiotic stress signalling in plants.

    PubMed

    Chinnusamy, Viswanathan; Schumaker, Karen; Zhu, Jian-Kang

    2004-01-01

    The perception of abiotic stresses and signal transduction to switch on adaptive responses are critical steps in determining the survival and reproduction of plants exposed to adverse environments. Plants have stress-specific adaptive responses as well as responses which protect the plants from more than one environmental stress. There are multiple stress perception and signalling pathways, some of which are specific, but others may cross-talk at various steps. Recently, progress has been made in identifying components of signalling pathways involved in salt, drought and cold stresses. Genetic analysis has defined the Salt-Overly-Sensitive (SOS) pathway, in which a salt stress-induced calcium signal is probably sensed by the calcium-binding protein SOS3 which then activates the protein kinase SOS2. The SOS3-SOS2 kinase complex regulates the expression and activity of ion transporters such as SOS1 to re-establish cellular ionic homeostasis under salinity. The ICE1 (Inducer of CBF Expression 1)-CBF (C-Repeat Binding Protein) pathway is critical for the regulation of the cold-responsive transcriptome and acquired freezing tolerance, although at present the signalling events that activate the ICE1 transcription factor during cold stress are not known. Both ABA-dependent and -independent signalling pathways appear to be involved in osmotic stress tolerance. Components of mitogen-activated protein kinase (MAPK) cascades may act as converging points of multiple abiotic as well as biotic stress signalling pathways. Forward and reverse genetic analysis in combination with expression profiling will continue to uncover many signalling components, and biochemical characterization of the signalling complexes will be required to determine specificity and cross-talk in abiotic stress signalling pathways. PMID:14673035

  11. Combined effects of metal contamination and abiotic parameters on biomarker responses in clam Ruditapes decussatus gills: an integrated approach in biomonitoring of Tunis lagoon.

    PubMed

    Chalghmi, Houssem; Zrafi, Ines; Gourves, Pierre-Yves; Bourdineaud, Jean-Paul; Saidane-Mosbahi, Dalila

    2016-07-13

    The spatial and seasonal alteration in a battery of biomarkers responses (enzymatic activity of glutathione-S-transferase, catalase and acetylcholinesterase and lipid peroxidation) were investigated to assess the metal derived effects in clam (Ruditapes decussatus) gills, collected from Tunis lagoon (Tunisia). Trace metals (Ag, As, Cd, Cu, Hg, Mn, Ni, Pb, V and Zn) concentrations were assessed seasonally in sediments and tissues of R. decussatus from three different sites (S1, S2 and S3). Bioaccumulation factor (BAF) analysis showed a spatio-temporal variation of metal uptake rates in clams through sediments. Likewise, the multibiomarker approach enabled a time-site trend differentiation between sites with distinctive degrees of anthropogenic contamination. Site S2 was identified as the most impacted region due to the presence of different contamination sources (shipping and industrial activities). The results suggest that biomarker's seasonal variation arises from a complex interaction between environmental conditions (e.g. temperature, salinity) and probably biological factors (mainly the reproduction process) along with anthropogenic pressure. The general biological response measured with the IBR index at all the sampling sites revealed the highest metabolic stress in summer. The combined effects of metal contamination and increased temperature and salinity in summer appear to induce the highest metabolic adaptation response. The selected biomarkers provided an integrated response, which is useful for the assessment of the combined effects of metal contamination and abiotic parameters in clams and the environmental status of coastal lagoon ecosystem. PMID:27337063

  12. Maternal, social and abiotic environmental effects on growth vary across life stages in a cooperative mammal.

    PubMed

    English, Sinead; Bateman, Andrew W; Mares, Rafael; Ozgul, Arpat; Clutton-Brock, Tim H

    2014-03-01

    Resource availability plays a key role in driving variation in somatic growth and body condition, and the factors determining access to resources vary considerably across life stages. Parents and carers may exert important influences in early life, when individuals are nutritionally dependent, with abiotic environmental effects having stronger influences later in development as individuals forage independently. Most studies have measured specific factors influencing growth across development or have compared relative influences of different factors within specific life stages. Such studies may not capture whether early-life factors continue to have delayed effects at later stages, or whether social factors change when individuals become nutritionally independent and adults become competitors for, rather than providers of, food. Here, we examined variation in the influence of the abiotic, social and maternal environment on growth across life stages in a wild population of cooperatively breeding meerkats. Cooperatively breeding vertebrates are ideal for investigating environmental influences on growth. In addition to experiencing highly variable abiotic conditions, cooperative breeders are typified by heterogeneity both among breeders, with mothers varying in age and social status, and in the number of carers present. Recent rainfall had a consistently marked effect on growth across life stages, yet other seasonal terms only influenced growth during stages when individuals were growing fastest. Group size and maternal dominance status had positive effects on growth during the period of nutritional dependence on carers, but did not influence mass at emergence (at 1 month) or growth at independent stages (>4 months). Pups born to older mothers were lighter at 1 month of age and subsequently grew faster as subadults. Males grew faster than females during the juvenile and subadult stage only. Our findings demonstrate the complex ways in which the external environment

  13. Abiotic formation of acylglycerols under simulated hydrothermal conditions and self-assembly properties of such lipid products

    NASA Astrophysics Data System (ADS)

    Simoneit, Bernd R. T.; Rushdi, Ahmed I.; Deamer, David W.

    The abiotic formation of aliphatic lipid compounds (i.e., fatty acids, alcohols, and acylglycerols) has been reported to occur at elevated temperatures and pressures under simulated hydrothermal conditions. Although abiotic synthetic chemistry can occur under these conditions, the prebiotic self-assembly of micelles to bilayer to vesicles (protocells) may have occurred elsewhere. Amphiphilic compounds such as fatty acids are important candidates for micelle/bilayer/vesicle formation, because they are abundant products of Fischer-Tropsch-type reactions and are also found in carbonaceous meteorites. Thus, it is of interest to determine whether more complex amphiphilic precursor compounds, capable of assembling into stable membrane structures, can be synthesized under hydrothermal conditions. Hydrothermal experiments were conducted to study condensation reactions of model lipid precursors in aqueous media, i.e., glycerol and alkanoic acids, to form acylglycerols (glyceryl alkanoates) at elevated temperature under confining pressure. Nine different alkanoic acids ranging from C 7 to C 16 (except C 8) were used in these experiments. The condensation products were two isomers each of monoacylglycerols and diacylglycerols, as well as the corresponding triacylglycerol. The results indicated that: (1) condensation (dehydration) reactions are possible under aqueous pyrolysis conditions; (2) abiotic synthesis and subsequent condensation reactions of aliphatic lipid compounds are possible under hydrothermal conditions; and (3) such molecules have robust properties of self-assembly into membranous structures that would be suitable boundary structures for primitive forms of cellular life.

  14. Improvement of Polyunsaturated Fatty Acid Production in Echium acanthocarpum Transformed Hairy Root Cultures by Application of Different Abiotic Stress Conditions

    PubMed Central

    Zárate, Rafael; Cequier-Sánchez, Elena; Rodríguez, Covadonga; Dorta-Guerra, Roberto; El Jaber-Vazdekis, Nabil; Ravelo, Ángel G.

    2013-01-01

    Fatty acids are of great nutritional, therapeutic, and physiological importance, especially the polyunsaturated n-3 fatty acids, possessing larger carbon chains and abundant double bonds or their immediate precursors. A few higher plant species are able to accumulate these compounds, like those belonging to the Echium genus. Here, the novel E. acanthocarpum hairy root system, which is able to accumulate many fatty acids, including stearidonic and α-linolenic acids, was optimized for a better production. The application of abiotic stress resulted in larger yields of stearidonic and α-linolenic acids, 60 and 35%, respectively, with a decrease in linoleic acid, when grown in a nutrient medium consisting of B5 basal salts, sucrose or glucose, and, more importantly, at a temperature of 15°C. The application of osmotic stress employing sorbitol showed no positive influence on the fatty acid yields; furthermore, the combination of a lower culture temperature and glucose did not show a cumulative boosting effect on the yield, although this carbon source was similarly attractive. The abiotic stress also influenced the lipid profile of the cultures, significantly increasing the phosphatidylglycerol fraction but not the total lipid neither their biomass, proving the appropriateness of applying various abiotic stress in this culture to achieve larger yields. PMID:25937970

  15. Solar wind: A possible factor driving the interannual sea surface temperature tripolar mode over North Atlantic

    NASA Astrophysics Data System (ADS)

    Xiao, Ziniu; Li, Delin

    2016-06-01

    The effect of solar wind (SW) on the North Atlantic sea surface temperature (SST) in boreal winter is examined through an analysis of observational data during 1964-2013. The North Atlantic SSTs show a pronounced meridional tripolar pattern in response to solar wind speed (SWS) variations. This pattern is broadly similar to the leading empirical orthogonal function (EOF) mode of interannual variations in the wintertime SSTs over North Atlantic. The time series of this leading EOF mode of SST shows a significant interannual period, which is the same as that of wintertime SWS. This response also appears as a compact north-south seesaw of sea level pressure and a vertical tripolar structure of zonal wind, which simultaneously resembles the North Atlantic Oscillation (NAO) in the overlying atmosphere. As compared with the typical low SWS winters, during the typical high SWS winters, the stratospheric polar night jet (PNJ) is evidently enhanced and extends from the stratosphere to the troposphere, even down to the North Atlantic Ocean surface. Notably, the North Atlantic Ocean is an exclusive region in which the SW signal spreads downward from the stratosphere to the troposphere. Thus, it seems that the SW is a possible factor for this North Atlantic SST tripolar mode. The dynamical process of stratosphere-troposphere coupling, together with the global atmospheric electric circuit-cloud microphysical process, probably accounts for the particular downward propagation of the SW signal.

  16. Integrated biomarker responses of the invasive species Corbicula fluminea in relation to environmental abiotic conditions: a potential indicator of the likelihood of clam's summer mortality syndrome.

    PubMed

    Oliveira, Cristiana; Vilares, Pedro; Guilhermino, Lúcia

    2015-04-01

    The aim of this study was to investigate the variation of several biomarkers in wild populations of Corbicula fluminea in relation to abiotic condition changes to identify environmental factors associated with increased stress in this species potentially leading to massive mortality events. The study was carried out from July to October in the freshwater tidal areas of the estuaries of Minho and Lima Rivers (NW Iberian Peninsula). Monthly, 7 biomarkers (biotransformation, energy production, anti-oxidant defenses and lipid peroxidation damages) were determined in C. fluminea and 17 abiotic parameters were determined in water or sediments in 4 sampling sites: M1, M2 and M3 in Minho (up=> downstream); and L in Lima estuaries. The results of biomarkers were integrated using the Integrated Biomarker Response (IBR), Index and also analysed in relation to environmental parameters by Redundancy Analysis (RDA). Overall, the findings of the present study indicate that July and August are particularly stressful months for the studied C. fluminea populations, especially at downstream sites; the increase of nutrients and ammonium water concentrations, water temperature and conductivity are major contributors for this increased stress; the biomarkers indicated that in July/August C. fluminea is exposed to oxidative stress inducers, environmental chemical contaminants biotransformed by esterases and glutathione S-transferase enzymes, and that organisms need additional energy to cope with the chemical and/or thermally-induced stress. The findings of the present study stress the importance of biomonitoring the health condition of C. fluminea because it may allow determining the likelihood of summer/post summer mortality syndrome in this species. PMID:25499240

  17. Effects of abiotic stress on plants: a systems biology perspective

    PubMed Central

    2011-01-01

    The natural environment for plants is composed of a complex set of abiotic stresses and biotic stresses. Plant responses to these stresses are equally complex. Systems biology approaches facilitate a multi-targeted approach by allowing one to identify regulatory hubs in complex networks. Systems biology takes the molecular parts (transcripts, proteins and metabolites) of an organism and attempts to fit them into functional networks or models designed to describe and predict the dynamic activities of that organism in different environments. In this review, research progress in plant responses to abiotic stresses is summarized from the physiological level to the molecular level. New insights obtained from the integration of omics datasets are highlighted. Gaps in our knowledge are identified, providing additional focus areas for crop improvement research in the future. PMID:22094046

  18. Abiotic mediation of a mutualism drives herbivore abundance.

    PubMed

    Mooney, Emily H; Phillips, Joseph S; Tillberg, Chadwick V; Sandrow, Cheryl; Nelson, Annika S; Mooney, Kailen A

    2016-01-01

    Species abundance is typically determined by the abiotic environment, but the extent to which such effects occur through the mediation of biotic interactions, including mutualisms, is unknown. We explored how light environment (open meadow vs. shaded understory) mediates the abundance and ant tending of the aphid Aphis helianthi feeding on the herb Ligusticum porteri. Yearly surveys consistently found aphids to be more than 17-fold more abundant on open meadow plants than on shaded understory plants. Manipulations demonstrated that this abundance pattern was not due to the direct effects of light environment on aphid performance, or indirectly through host plant quality or the effects of predators. Instead, open meadows had higher ant abundance and per capita rates of aphid tending and, accordingly, ants increased aphid population growth in meadow but not understory environments. The abiotic environment thus drives the abundance of this herbivore exclusively through the mediation of a protection mutualism. PMID:26563752

  19. Trends of abiotic damage in forest ecosystems in Germany at regional scale under SRES A1B, B1

    NASA Astrophysics Data System (ADS)

    Panferov, O.; Doering, C.; Sogachev, A.; Merklein, J.; Ahrends, B.

    2009-09-01

    Current climate projections indicate that the ongoing climate change may cause an increase of frequency of weather extremes (Leckebusch et al., 2008), which can result in wide area abiotic and consequent biotic damage events (e.g. drought and following insect attacks) within forest ecosystems. The type and degree of damage depends not only on the strength of a primary driving force itself (e.g. wind speed) but also on complex interactions between combinations of effecting agents with above- and belowground forest structure characteristics. The present study investigates the projected trends of abiotic risks factors and their combinations on coniferous and deciduous forests during the 21st Century under conditions of SRES scenarios A1B and B1. The downscaling of ECHAM5-MPIOM by the regional climate model (CLM) to the spatial resolution of 0.2° x 0.2° with daily time-steps is used for the analysis of future climate extremes and their combinations. With these input data the small-scale modeling with coupled process based sub-models (Jansen et al., 2008) was carried out for Solling region, (Central Germany) calculating the water and energy balance of spruce and beech forest ecosystems on cambisols and podzols with BROOK90 (Federer et al. 2003) and wind loading on trees with 3D ABL model SCADIS (Panferov and Sogachev, 2008). The risks of drought or wind damage for a certain forest stand result from combinations of soil water characteristics, static and gust wind loads, which in turn depend on current above- and belowground tree structure and on soil texture. The actual soil water content and forest structure depends on climate-soil-vegetation interactions in previous years. Therefore, differences of microclimatological conditions in the remaining stand after changes in forest structure are taken into account. Model outputs are aggregated to 30-years periods and compared to "present” conditions of 1971-2000. The results demonstrate an increment of abiotic risks

  20. Spatial variability of biotic and abiotic tree establishment constraints across a treeline ecotone in the Alaska Range

    USGS Publications Warehouse

    Stueve, K.M.; Isaacs, R.E.; Tyrrell, L.E.; Densmore, R.V.

    2011-01-01

    Throughout interior Alaska (USA), a gradual warming trend in mean monthly temperatures occurred over the last few decades (;2-48C). The accompanying increases in woody vegetation at many alpine treeline (hereafter treeline) locations provided an opportunity to examine how biotic and abiotic local site conditions interact to control tree establishment patterns during warming. We devised a landscape ecological approach to investigate these relationships at an undisturbed treeline in the Alaska Range. We identified treeline changes between 1953 (aerial photography) and 2005 (satellite imagery) in a geographic information system (GIS) and linked them with corresponding local site conditions derived from digital terrain data, ancillary climate data, and distance to 1953 trees. Logistic regressions enabled us to rank the importance of local site conditions in controlling tree establishment. We discovered a spatial transition in the importance of tree establishment controls. The biotic variable (proximity to 1953 trees) was the most important tree establishment predictor below the upper tree limit, providing evidence of response lags with the abiotic setting and suggesting that tree establishment is rarely in equilibrium with the physical environment or responding directly to warming. Elevation and winter sun exposure were important predictors of tree establishment at the upper tree limit, but proximity to trees persisted as an important tertiary predictor, indicating that tree establishment may achieve equilibrium with the physical environment. However, even here, influences from the biotic variable may obscure unequivocal correlations with the abiotic setting (including temperature). Future treeline expansion will likely be patchy and challenging to predict without considering the spatial variability of influences from biotic and abiotic local site conditions. ?? 2011 by the Ecological Society of America.

  1. Homeologous genes involved in mannitol synthesis reveal unequal contributions in response to abiotic stress in Coffea arabica.

    PubMed

    de Carvalho, Kenia; Petkowicz, Carmen L O; Nagashima, Getulio T; Bespalhok Filho, João C; Vieira, Luiz G E; Pereira, Luiz F P; Domingues, Douglas S

    2014-10-01

    Polyploid plants can exhibit transcriptional modulation in homeologous genes in response to abiotic stresses. Coffea arabica, an allotetraploid, accounts for 75% of the world's coffee production. Extreme temperatures, salinity and drought limit crop productivity, which includes coffee plants. Mannitol is known to be involved in abiotic stress tolerance in higher plants. This study aimed to investigate the transcriptional responses of genes involved in mannitol biosynthesis and catabolism in C. arabica leaves under water deficit, salt stress and high temperature. Mannitol concentration was significantly increased in leaves of plants under drought and salinity, but reduced by heat stress. Fructose content followed the level of mannitol only in heat-stressed plants, suggesting the partitioning of the former into other metabolites during drought and salt stress conditions. Transcripts of the key enzymes involved in mannitol biosynthesis, CaM6PR, CaPMI and CaMTD, were modulated in distinct ways depending on the abiotic stress. Our data suggest that changes in mannitol accumulation during drought and salt stress in leaves of C. arabica are due, at least in part, to the increased expression of the key genes involved in mannitol biosynthesis. In addition, the homeologs of the Coffea canephora subgenome did not present the same pattern of overall transcriptional response, indicating differential regulation of these genes by the same stimulus. In this way, this study adds new information on the differential expression of C. arabica homeologous genes under adverse environmental conditions showing that abiotic stresses can influence the homeologous gene regulation pattern, in this case, mainly on those involved in mannitol pathway. PMID:24861101

  2. Wheat EST resources for functional genomics of abiotic stress

    PubMed Central

    Houde, Mario; Belcaid, Mahdi; Ouellet, François; Danyluk, Jean; Monroy, Antonio F; Dryanova, Ani; Gulick, Patrick; Bergeron, Anne; Laroche, André; Links, Matthew G; MacCarthy, Luke; Crosby, William L; Sarhan, Fathey

    2006-01-01

    Background Wheat is an excellent species to study freezing tolerance and other abiotic stresses. However, the sequence of the wheat genome has not been completely characterized due to its complexity and large size. To circumvent this obstacle and identify genes involved in cold acclimation and associated stresses, a large scale EST sequencing approach was undertaken by the Functional Genomics of Abiotic Stress (FGAS) project. Results We generated 73,521 quality-filtered ESTs from eleven cDNA libraries constructed from wheat plants exposed to various abiotic stresses and at different developmental stages. In addition, 196,041 ESTs for which tracefiles were available from the National Science Foundation wheat EST sequencing program and DuPont were also quality-filtered and used in the analysis. Clustering of the combined ESTs with d2_cluster and TGICL yielded a few large clusters containing several thousand ESTs that were refractory to routine clustering techniques. To resolve this problem, the sequence proximity and "bridges" were identified by an e-value distance graph to manually break clusters into smaller groups. Assembly of the resolved ESTs generated a 75,488 unique sequence set (31,580 contigs and 43,908 singletons/singlets). Digital expression analyses indicated that the FGAS dataset is enriched in stress-regulated genes compared to the other public datasets. Over 43% of the unique sequence set was annotated and classified into functional categories according to Gene Ontology. Conclusion We have annotated 29,556 different sequences, an almost 5-fold increase in annotated sequences compared to the available wheat public databases. Digital expression analysis combined with gene annotation helped in the identification of several pathways associated with abiotic stress. The genomic resources and knowledge developed by this project will contribute to a better understanding of the different mechanisms that govern stress tolerance in wheat and other cereals. PMID

  3. Role of Extracellular Structures of Escherichia coli O157:H7 in Initial Attachment to Biotic and Abiotic Surfaces

    PubMed Central

    Nagy, Attila; Mowery, Joseph; Bauchan, Gary R.; Wang, Lili; Nichols-Russell, Lydia

    2015-01-01

    Infection by human pathogens through the consumption of fresh, minimally processed produce and solid plant-derived foods is a major concern of the U.S. and global food industries and of public health services. Enterohemorrhagic Escherichia coli O157:H7 is a frequent and potent foodborne pathogen that causes severe disease in humans. Biofilms formed by E. coli O157:H7 facilitate cross-contamination by sheltering pathogens and protecting them from cleaning and sanitation operations. The objective of this research was to determine the role that several surface structures of E. coli O157:H7 play in adherence to biotic and abiotic surfaces. A set of isogenic deletion mutants lacking major surface structures was generated. The mutant strains were inoculated onto fresh spinach and glass surfaces, and their capability to adhere was assessed by adherence assays and fluorescence microscopy methods. Our results showed that filament-deficient mutants bound to the spinach leaves and glass surfaces less strongly than the wild-type strain did. We mimicked the switch to the external environment—during which bacteria leave the host organism and adapt to lower ambient temperatures of cultivation or food processing—by decreasing the temperature from 37°C to 25°C and 4°C. We concluded that flagella and some other cell surface proteins are important factors in the process of initial attachment and in the establishment of biofilms. A better understanding of the specific roles of these structures in early stages of biofilm formation can help to prevent cross-contaminations and foodborne disease outbreaks. PMID:25956766

  4. The effective quality factor at low temperatures in dynamic force microscopes with Fabry-Pérot interferometer detection

    NASA Astrophysics Data System (ADS)

    Hölscher, Hendrik; Milde, Peter; Zerweck, Ulrich; Eng, Lukas M.; Hoffmann, Regina

    2009-06-01

    The oscillation of a cantilever in ultrahigh vacuum dynamic force microscopy is sometimes measured with the help of a Fabry-Pérot interferometer. We show that the photoinduced forces present in such an interferometer can artificially increase or decrease the effective quality factor of the cantilever. We examine this effect on the basis of a PtIr-coated rectangular silicon cantilever at temperatures between 7.7 and 30 K. By measuring resonance curves we demonstrate that the magnitude of the effective quality factor changes with cantilever-fiber distance, laser power, and temperature.

  5. Temperature and substrate chemistry as major drivers of interregional variability of leaf microbial decomposition and cellulolytic activity in headwater streams.

    PubMed

    Fenoy, Encarnación; Casas, J Jesús; Díaz-López, Manuel; Rubio, Juan; Guil-Guerrero, J Luís; Moyano-López, Francisco J

    2016-11-01

    Abiotic factors, substrate chemistry and decomposers community composition are primary drivers of leaf litter decomposition. In soil, much of the variation in litter decomposition is explained by climate and substrate chemistry, but with a significant contribution of the specialisation of decomposer communities to degrade specific substrates (home-field advantage, HFA). In streams, however, HFA effects on litter decomposition have not been explicitly tested. We evaluated responses of microbial decomposition and β-glucosidase activity to abiotic factors, substrate and decomposer assemblages, using a reciprocal litter transplant experiment: 'ecosystem type' (mountain vs lowland streams) × 'litter chemistry' (alder vs reed). Temperature, pH and ionic concentration were higher in lowland streams. Decomposition for both species was faster in lowland streams. Decomposition of reed was more accelerated in lowland compared with mountain streams than that of alder, suggesting higher temperature sensitivity of decomposition in reed. Q10 (5°C-15°C) values of β-glucosidase activity were over 2. The alkaline pH and high ionic concentration of lowland streams depleted enzyme activity. We found similar relationships of decomposition or enzyme activity with abiotic factors for both species, suggesting limited support to the HFA hypothesis. Overall, our results suggest a prime role of temperature interacting with substrate chemistry on litter decomposition. PMID:27515735

  6. Abiotic carbonate dissolution traps carbon in a semiarid desert

    NASA Astrophysics Data System (ADS)

    Fa, Keyu; Liu, Zhen; Zhang, Yuqing; Qin, Shugao; Wu, Bin; Liu, Jiabin

    2016-03-01

    It is generally considered that desert ecosystems release CO2 to the atmosphere, but recent studies in drylands have shown that the soil can absorb CO2 abiotically. However, the mechanisms and exact location of abiotic carbon absorption remain unclear. Here, we used soil sterilization, 13CO2 addition, and detection methods to trace 13C in the soil of the Mu Us Desert, northern China. After 13CO2 addition, a large amount of 13CO2 was absorbed by the sterilised soil, and 13C was found enriched both in the soil gaseous phase and dissolved inorganic carbon (DIC). Further analysis indicated that about 79.45% of the total 13C absorbed by the soil was trapped in DIC, while the amount of 13C in the soil gaseous phase accounted for only 0.22% of the total absorbed 13C. However, about 20.33% of the total absorbed 13C remained undetected. Our results suggest that carbonate dissolution might occur predominately, and the soil liquid phase might trap the majority of abiotically absorbed carbon. It is possible that the trapped carbon in the soil liquid phase leaches into the groundwater; however, further studies are required to support this hypothesis.

  7. Biotic and abiotic mercury methylation and demethylation in sediments

    SciTech Connect

    Zhang, L.; Planas, D. )

    1994-05-01

    Inorganic mercury (Hg(II)) methylation and methylmercury (MeHg) demethylation may occur in the water column, sediment-water interface and subsurficial sediment of aquatic ecosystems. These transformations involve mainly microbial mechanisms, although abiotic methylation may play a more important role in the water compartment. The relative importance of biotic versus abiotic mechanisms of methylation has not been determined however, and abiotic demethylation remains unknown. Little quantitative information is available on the role of bacterial activity in mercury transformations. It has been reported that at least 16 genera of aerobic and anaerobic microorganisms are able to methylate HG(II), and that a greater number are able to demethylate MeHg. Nevertheless, not all populations of these species are capable of methyl- and demethyl-transformations. The actual concentration of MeHg in the aquatic environment is regulated by the relative production and decomposition rates. This, in turn, depends on the availability of Hg(II), MeHg, and bacteria as well as on the physico-chemical properties of the sample. The objective of this study was to compare mercury methylation and demethylation rates in sediment samples with and without active bacterial populations. We therefore performed experiments to follow bacterial evolution during the course of Hg(II) methylation and MeHg demethylation in sediment slurries containing both sterile and non-sterile sediments.

  8. Abiotic Deposition of Fe Complexes onto Leptothrix Sheaths

    PubMed Central

    Kunoh, Tatsuki; Hashimoto, Hideki; McFarlane, Ian R.; Hayashi, Naoaki; Suzuki, Tomoko; Taketa, Eisuke; Tamura, Katsunori; Takano, Mikio; El-Naggar, Mohamed Y.; Kunoh, Hitoshi; Takada, Jun

    2016-01-01

    Bacteria classified in species of the genus Leptothrix produce extracellular, microtubular, Fe-encrusted sheaths. The encrustation has been previously linked to bacterial Fe oxidases, which oxidize Fe(II) to Fe(III) and/or active groups of bacterial exopolymers within sheaths to attract and bind aqueous-phase inorganics. When L. cholodnii SP-6 cells were cultured in media amended with high Fe(II) concentrations, Fe(III) precipitates visibly formed immediately after addition of Fe(II) to the medium, suggesting prompt abiotic oxidation of Fe(II) to Fe(III). Intriguingly, these precipitates were deposited onto the sheath surface of bacterial cells as the population was actively growing. When Fe(III) was added to the medium, similar precipitates formed in the medium first and were abiotically deposited onto the sheath surfaces. The precipitates in the Fe(II) medium were composed of assemblies of globular, amorphous particles (ca. 50 nm diameter), while those in the Fe(III) medium were composed of large, aggregated particles (≥3 µm diameter) with a similar amorphous structure. These precipitates also adhered to cell-free sheaths. We thus concluded that direct abiotic deposition of Fe complexes onto the sheath surface occurs independently of cellular activity in liquid media containing Fe salts, although it remains unclear how this deposition is associated with the previously proposed mechanisms (oxidation enzyme- and/or active group of organic components-involved) of Fe encrustation of the Leptothrix sheaths. PMID:27271677

  9. Abiotic Deposition of Fe Complexes onto Leptothrix Sheaths.

    PubMed

    Kunoh, Tatsuki; Hashimoto, Hideki; McFarlane, Ian R; Hayashi, Naoaki; Suzuki, Tomoko; Taketa, Eisuke; Tamura, Katsunori; Takano, Mikio; El-Naggar, Mohamed Y; Kunoh, Hitoshi; Takada, Jun

    2016-01-01

    Bacteria classified in species of the genus Leptothrix produce extracellular, microtubular, Fe-encrusted sheaths. The encrustation has been previously linked to bacterial Fe oxidases, which oxidize Fe(II) to Fe(III) and/or active groups of bacterial exopolymers within sheaths to attract and bind aqueous-phase inorganics. When L. cholodnii SP-6 cells were cultured in media amended with high Fe(II) concentrations, Fe(III) precipitates visibly formed immediately after addition of Fe(II) to the medium, suggesting prompt abiotic oxidation of Fe(II) to Fe(III). Intriguingly, these precipitates were deposited onto the sheath surface of bacterial cells as the population was actively growing. When Fe(III) was added to the medium, similar precipitates formed in the medium first and were abiotically deposited onto the sheath surfaces. The precipitates in the Fe(II) medium were composed of assemblies of globular, amorphous particles (ca. 50 nm diameter), while those in the Fe(III) medium were composed of large, aggregated particles (≥3 µm diameter) with a similar amorphous structure. These precipitates also adhered to cell-free sheaths. We thus concluded that direct abiotic deposition of Fe complexes onto the sheath surface occurs independently of cellular activity in liquid media containing Fe salts, although it remains unclear how this deposition is associated with the previously proposed mechanisms (oxidation enzyme- and/or active group of organic components-involved) of Fe encrustation of the Leptothrix sheaths. PMID:27271677

  10. Titania may produce abiotic oxygen atmospheres on habitable exoplanets.

    PubMed

    Narita, Norio; Enomoto, Takafumi; Masaoka, Shigeyuki; Kusakabe, Nobuhiko

    2015-01-01

    The search for habitable exoplanets in the Universe is actively ongoing in the field of astronomy. The biggest future milestone is to determine whether life exists on such habitable exoplanets. In that context, oxygen in the atmosphere has been considered strong evidence for the presence of photosynthetic organisms. In this paper, we show that a previously unconsidered photochemical mechanism by titanium (IV) oxide (titania) can produce abiotic oxygen from liquid water under near ultraviolet (NUV) lights on the surface of exoplanets. Titania works as a photocatalyst to dissociate liquid water in this process. This mechanism offers a different source of a possibility of abiotic oxygen in atmospheres of exoplanets from previously considered photodissociation of water vapor in upper atmospheres by extreme ultraviolet (XUV) light. Our order-of-magnitude estimation shows that possible amounts of oxygen produced by this abiotic mechanism can be comparable with or even more than that in the atmosphere of the current Earth, depending on the amount of active surface area for this mechanism. We conclude that titania may act as a potential source of false signs of life on habitable exoplanets. PMID:26354078

  11. Titania may produce abiotic oxygen atmospheres on habitable exoplanets

    PubMed Central

    Narita, Norio; Enomoto, Takafumi; Masaoka, Shigeyuki; Kusakabe, Nobuhiko

    2015-01-01

    The search for habitable exoplanets in the Universe is actively ongoing in the field of astronomy. The biggest future milestone is to determine whether life exists on such habitable exoplanets. In that context, oxygen in the atmosphere has been considered strong evidence for the presence of photosynthetic organisms. In this paper, we show that a previously unconsidered photochemical mechanism by titanium (IV) oxide (titania) can produce abiotic oxygen from liquid water under near ultraviolet (NUV) lights on the surface of exoplanets. Titania works as a photocatalyst to dissociate liquid water in this process. This mechanism offers a different source of a possibility of abiotic oxygen in atmospheres of exoplanets from previously considered photodissociation of water vapor in upper atmospheres by extreme ultraviolet (XUV) light. Our order-of-magnitude estimation shows that possible amounts of oxygen produced by this abiotic mechanism can be comparable with or even more than that in the atmosphere of the current Earth, depending on the amount of active surface area for this mechanism. We conclude that titania may act as a potential source of false signs of life on habitable exoplanets. PMID:26354078

  12. Abiotic carbonate dissolution traps carbon in a semiarid desert

    PubMed Central

    Fa, Keyu; Liu, Zhen; Zhang, Yuqing; Qin, Shugao; Wu, Bin; Liu, Jiabin

    2016-01-01

    It is generally considered that desert ecosystems release CO2 to the atmosphere, but recent studies in drylands have shown that the soil can absorb CO2 abiotically. However, the mechanisms and exact location of abiotic carbon absorption remain unclear. Here, we used soil sterilization, 13CO2 addition, and detection methods to trace 13C in the soil of the Mu Us Desert, northern China. After 13CO2 addition, a large amount of 13CO2 was absorbed by the sterilised soil, and 13C was found enriched both in the soil gaseous phase and dissolved inorganic carbon (DIC). Further analysis indicated that about 79.45% of the total 13C absorbed by the soil was trapped in DIC, while the amount of 13C in the soil gaseous phase accounted for only 0.22% of the total absorbed 13C. However, about 20.33% of the total absorbed 13C remained undetected. Our results suggest that carbonate dissolution might occur predominately, and the soil liquid phase might trap the majority of abiotically absorbed carbon. It is possible that the trapped carbon in the soil liquid phase leaches into the groundwater; however, further studies are required to support this hypothesis. PMID:27020762

  13. Abiotic Reductive Immobilization of U(VI) by Biogenic Mackinawite

    SciTech Connect

    Veeramani, Harish; Scheinost, Andreas; Monsegue, Niven; Qafoku, Nikolla; Kukkadapu, Ravi K.; Newville, Mathew; Lanzirotti, Anthony; Pruden, Amy; Murayama, Mitsuhiro; Hochella, Michael F.

    2013-03-01

    During subsurface bioremediation of uranium-contaminated sites, indigenous metal and sulfate-reducing bacteria may utilize a variety of electron acceptors, including ferric iron and sulfate that could lead to the formation of various biogenic minerals in-situ. Sulfides, as well as structural and adsorbed Fe(II) associated with biogenic Fe(II)-sulfide phases, can potentially catalyze abiotic U6+ reduction via direct electron transfer processes. In the present work, the propensity of biogenic mackinawite (Fe1+xS, x = 0 to 0.11) to reduce U6+ abiotically was investigated. The biogenic mackinawite produced by Shewanella putrefaciens strain CN32 was characterized by employing a suite of analytical techniques including TEM, SEM, XAS and Mössbauer analyses. Nanoscale and bulk analyses (microscopic and spectroscopic techniques, respectively) of biogenic mackinawite after exposure to U6+ indicate the formation of nanoparticulate UO2. This study suggests the relevance of Fe(II) and sulfide bearing biogenic minerals in mediating abiotic U6+ reduction, an alternative pathway in addition to direct enzymatic U6+ reduction.

  14. Abscisic Acid and Abiotic Stress Tolerance in Crop Plants

    PubMed Central

    Sah, Saroj K.; Reddy, Kambham R.; Li, Jiaxu

    2016-01-01

    Abiotic stress is a primary threat to fulfill the demand of agricultural production to feed the world in coming decades. Plants reduce growth and development process during stress conditions, which ultimately affect the yield. In stress conditions, plants develop various stress mechanism to face the magnitude of stress challenges, although that is not enough to protect them. Therefore, many strategies have been used to produce abiotic stress tolerance crop plants, among them, abscisic acid (ABA) phytohormone engineering could be one of the methods of choice. ABA is an isoprenoid phytohormone, which regulates various physiological processes ranging from stomatal opening to protein storage and provides adaptation to many stresses like drought, salt, and cold stresses. ABA is also called an important messenger that acts as the signaling mediator for regulating the adaptive response of plants to different environmental stress conditions. In this review, we will discuss the role of ABA in response to abiotic stress at the molecular level and ABA signaling. The review also deals with the effect of ABA in respect to gene expression. PMID:27200044

  15. Titania may produce abiotic oxygen atmospheres on habitable exoplanets

    NASA Astrophysics Data System (ADS)

    Narita, Norio; Enomoto, Takafumi; Masaoka, Shigeyuki; Kusakabe, Nobuhiko

    2015-12-01

    The search for habitable exoplanets in the Universe is actively ongoing in the field of astronomy. The biggest future milestone is to determine whether life exists on such habitable exoplanets. In that context, oxygen in the atmosphere has been considered strong evidence for the presence of photosynthetic organisms. In this paper, we show that a previously unconsidered photochemical mechanism by titanium (IV) oxide (titania) can produce abiotic oxygen from liquid water under near ultraviolet (NUV) lights on the surface of exoplanets. Titania works as a photocatalyst to dissociate liquid water in this process. This mechanism offers a different source of a possibility of abiotic oxygen in atmospheres of exoplanets from previously considered photodissociation of water vapor in upper atmospheres by extreme ultraviolet (XUV) light. Our order-of-magnitude estimation shows that possible amounts of oxygen produced by this abiotic mechanism can be comparable with or even more than that in the atmosphere of the current Earth, depending on the amount of active surface area for this mechanism. We conclude that titania may act as a potential source of false signs of life on habitable exoplanets.Reference:Narita N. et al.,Scientific Reports 5, Article number: 13977 (2015)http://www.nature.com/articles/srep13977

  16. Cell Wall Metabolism in Response to Abiotic Stress

    PubMed Central

    Gall, Hyacinthe Le; Philippe, Florian; Domon, Jean-Marc; Gillet, Françoise; Pelloux, Jérôme; Rayon, Catherine

    2015-01-01

    This review focuses on the responses of the plant cell wall to several abiotic stresses including drought, flooding, heat, cold, salt, heavy metals, light, and air pollutants. The effects of stress on cell wall metabolism are discussed at the physiological (morphogenic), transcriptomic, proteomic and biochemical levels. The analysis of a large set of data shows that the plant response is highly complex. The overall effects of most abiotic stress are often dependent on the plant species, the genotype, the age of the plant, the timing of the stress application, and the intensity of this stress. This shows the difficulty of identifying a common pattern of stress response in cell wall architecture that could enable adaptation and/or resistance to abiotic stress. However, in most cases, two main mechanisms can be highlighted: (i) an increased level in xyloglucan endotransglucosylase/hydrolase (XTH) and expansin proteins, associated with an increase in the degree of rhamnogalacturonan I branching that maintains cell wall plasticity and (ii) an increased cell wall thickening by reinforcement of the secondary wall with hemicellulose and lignin deposition. Taken together, these results show the need to undertake large-scale analyses, using multidisciplinary approaches, to unravel the consequences of stress on the cell wall. This will help identify the key components that could be targeted to improve biomass production under stress conditions. PMID:27135320

  17. Cell Wall Metabolism in Response to Abiotic Stress.

    PubMed

    Le Gall, Hyacinthe; Philippe, Florian; Domon, Jean-Marc; Gillet, Françoise; Pelloux, Jérôme; Rayon, Catherine

    2015-01-01

    This review focuses on the responses of the plant cell wall to several abiotic stresses including drought, flooding, heat, cold, salt, heavy metals, light, and air pollutants. The effects of stress on cell wall metabolism are discussed at the physiological (morphogenic), transcriptomic, proteomic and biochemical levels. The analysis of a large set of data shows that the plant response is highly complex. The overall effects of most abiotic stress are often dependent on the plant species, the genotype, the age of the plant, the timing of the stress application, and the intensity of this stress. This shows the difficulty of identifying a common pattern of stress response in cell wall architecture that could enable adaptation and/or resistance to abiotic stress. However, in most cases, two main mechanisms can be highlighted: (i) an increased level in xyloglucan endotransglucosylase/hydrolase (XTH) and expansin proteins, associated with an increase in the degree of rhamnogalacturonan I branching that maintains cell wall plasticity and (ii) an increased cell wall thickening by reinforcement of the secondary wall with hemicellulose and lignin deposition. Taken together, these results show the need to undertake large-scale analyses, using multidisciplinary approaches, to unravel the consequences of stress on the cell wall. This will help identify the key components that could be targeted to improve biomass production under stress conditions. PMID:27135320

  18. On the discharge capability and its limiting factors of commercial 18650 Li-ion cell at low temperatures

    NASA Astrophysics Data System (ADS)

    Fan, Jiang

    We here study the discharge capability of commercial 18650 cylindrical lithium-ion cells at low temperatures. The discharge capacity at -20 °C ranges from 67 to 88% of the rated capacity at 0.2 C rate, which is good. However, the cell discharge capacity varies substantially at -30 and -40 °C among the studied cells. It ranges from 2 to 70% of the rated capacity at -30 °C, and 0 to 30% at -40 °C at 0.2 C rate. The cell impedance at 1 kHz increases very little from room temperature down to -20 or -30 °C in general, which does not correlate with the cell discharge capability. However, the dc impedance is increased by a factor of about ten at -30 °C and about twenty at -40 °C from room temperature. The discharge capability at low temperature correlates well with the dc resistance at both room and low temperatures. The limiting factors in the discharge capability at low temperatures and the direction for the future improvement are discussed according to the cell discharge capability, the electrode geometric area, the cell impedance at 1 kHz, and the dc impedance at various temperatures. It appears that the ionic conductivity of the electrolyte and lithium solid diffusion in the electrode do not limit the cell discharge capability, while the lithium diffusion in the SEI layer on the positive surface may be the limiting factor. Cell discharge capability at low temperature does not correlate with cycle life at room temperature.

  19. Monte Carlo Simulation Using Johnson Potential on Gd-Mg Alloy for Debye-Waller Factor and Debye Temperature

    NASA Astrophysics Data System (ADS)

    Chitra, S.; Ramachandran, K.

    Monte Carlo simulation (MCS) on the thermal properties in Gd-Mg alloy becomes essential as there are only limited experiments available. A realistic Johnson potential is used to workout the specific heats for various temperatures and hence the Debye temperature. The results from the present simulation technique are very well compared with our shell model calculation. The need of better X-ray measurements for Debye-Waller factor and Debye temperature other than the measurements of Subadhra and Sirdeshmukh, is discussed in detail.

  20. The spliceosome assembly factor GEMIN2 attenuates the effects of temperature on alternative splicing and circadian rhythms

    PubMed Central

    Schlaen, Rubén Gustavo; Mancini, Estefanía; Sanchez, Sabrina Elena; Perez-Santángelo, Soledad; Rugnone, Matías L.; Simpson, Craig G.; Brown, John W. S.; Zhang, Xu; Chernomoretz, Ariel; Yanovsky, Marcelo J.

    2015-01-01

    The mechanisms by which poikilothermic organisms ensure that biological processes are robust to temperature changes are largely unknown. Temperature compensation, the ability of circadian rhythms to maintain a relatively constant period over the broad range of temperatures resulting from seasonal fluctuations in environmental conditions, is a defining property of circadian networks. Temperature affects the alternative splicing (AS) of several clock genes in fungi, plants, and flies, but the splicing factors that modulate these effects to ensure clock accuracy throughout the year remain to be identified. Here we show that GEMIN2, a spliceosomal small nuclear ribonucleoprotein assembly factor conserved from yeast to humans, modulates low temperature effects on a large subset of pre-mRNA splicing events. In particular, GEMIN2 controls the AS of several clock genes and attenuates the effects of temperature on the circadian period in Arabidopsis thaliana. We conclude that GEMIN2 is a key component of a posttranscriptional regulatory mechanism that ensures the appropriate acclimation of plants to daily and seasonal changes in temperature conditions. PMID:26170331

  1. Temperature-averaged and total free-free Gaunt factors for κ and Maxwellian distributions of electrons

    NASA Astrophysics Data System (ADS)

    de Avillez, Miguel A.; Breitschwerdt, Dieter

    2015-08-01

    Aims: Optically thin plasmas may deviate from thermal equilibrium and thus, electrons (and ions) are no longer described by the Maxwellian distribution. Instead they can be described by κ-distributions. The free-free spectrum and radiative losses depend on the temperature-averaged (over the electrons distribution) and total Gaunt factors, respectively. Thus, there is a need to calculate and make available these factors to be used by any software that deals with plasma emission. Methods: We recalculated the free-free Gaunt factor for a wide range of energies and frequencies using hypergeometric functions of complex arguments and the Clenshaw recurrence formula technique combined with approximations whenever the difference between the initial and final electron energies is smaller than 10-10 in units of z2Ry. We used double and quadruple precisions. The temperature-averaged and total Gaunt factors calculations make use of the Gauss-Laguerre integration with 128 nodes. Results: The temperature-averaged and total Gaunt factors depend on the κ parameter, which shows increasing deviations (with respect to the results obtained with the use of the Maxwellian distribution) with decreasing κ. Tables of these Gaunt factors are provided. Appendices are available in electronic form at http://www.aanda.org

  2. MusaWRKY71 overexpression in banana plants leads to altered abiotic and biotic stress responses.

    PubMed

    Shekhawat, Upendra K S; Ganapathi, Thumballi R

    2013-01-01

    WRKY transcription factors are specifically involved in the transcriptional reprogramming following incidence of abiotic or biotic stress on plants. We have previously documented a novel WRKY gene from banana, MusaWRKY71, which was inducible in response to a wide array of abiotic or biotic stress stimuli. The present work details the effects of MusaWRKY71 overexpression in transgenic banana plants. Stable integration and overexpression of MusaWRKY71 in transgenic banana plants was proved by Southern blot analysis and quantitative real time PCR. Transgenic banana plants overexpressing MusaWRKY71 displayed enhanced tolerance towards oxidative and salt stress as indicated by better photosynthesis efficiency (Fv/Fm) and lower membrane damage of the assayed leaves. Further, differential regulation of putative downstream genes of MusaWRKY71 was investigated using real-time RT-PCR expression analysis. Out of a total of 122 genes belonging to WRKY, pathogenesis-related (PR) protein genes, non-expressor of pathogenesis-related genes 1 (NPR1) and chitinase families analyzed, 10 genes (six belonging to WRKY family, three belonging to PR proteins family and one belonging to chitinase family) showed significant differential regulation in MusaWRKY71 overexpressing lines. These results indicate that MusaWRKY71 is an important constituent in the transcriptional reprogramming involved in diverse stress responses in banana. PMID:24116051

  3. MusaWRKY71 Overexpression in Banana Plants Leads to Altered Abiotic and Biotic Stress Responses

    PubMed Central

    Shekhawat, Upendra K. S.; Ganapathi, Thumballi R.

    2013-01-01

    WRKY transcription factors are specifically involved in the transcriptional reprogramming following incidence of abiotic or biotic stress on plants. We have previously documented a novel WRKY gene from banana, MusaWRKY71, which was inducible in response to a wide array of abiotic or biotic stress stimuli. The present work details the effects of MusaWRKY71 overexpression in transgenic banana plants. Stable integration and overexpression of MusaWRKY71 in transgenic banana plants was proved by Southern blot analysis and quantitative real time PCR. Transgenic banana plants overexpressing MusaWRKY71 displayed enhanced tolerance towards oxidative and salt stress as indicated by better photosynthesis efficiency (Fv/Fm) and lower membrane damage of the assayed leaves. Further, differential regulation of putative downstream genes of MusaWRKY71 was investigated using real-time RT-PCR expression analysis. Out of a total of 122 genes belonging to WRKY, pathogenesis-related (PR) protein genes, non-expressor of pathogenesis-related genes 1 (NPR1) and chitinase families analyzed, 10 genes (six belonging to WRKY family, three belonging to PR proteins family and one belonging to chitinase family) showed significant differential regulation in MusaWRKY71 overexpressing lines. These results indicate that MusaWRKY71 is an important constituent in the transcriptional reprogramming involved in diverse stress responses in banana. PMID:24116051

  4. Abiotic influences on the biomass of Vallisneria americana Michx. In the Upper Mississippi River

    USGS Publications Warehouse

    Kreiling, Rebecca M.; Yin, Y.; Gerber, D.T.

    2007-01-01

    American wildcelery, Vallisneria americana Michx. is an ecologically important component of aquatic communities in the Upper Mississippi River (UMR). We conducted a study in 2002 to determine the association of several abiotic factors on the vegetative growth of Vallisneria in Navigation Pool 8 (Pool 8) of the UMR. We measured turbidity, percent light absorbance, surface water ammonium, surface water nitrate, current velocity, conductivity, pH and water depth throughout one growing season at 56 stratified sites based on where Vallisneria occurred in previous years. Sediment and aboveground biomass samples were collected during peak growth. Sediment was analysed for organic content, particle size, pore water nitrate and pore water ammonium. Vallisneria biomass samples were dried to constant mass. Because some sites were without water for much of the growing season, only data from 52 sites were reported. Biomass was associated with depth, percent light absorbance, turbidity and wind fetch. Vallisneria was abundant in the depth range of 0.55 to 1.03 m, in areas receiving at least 38% of surface light and in areas exposed to greater wind fetch (>2000 m). Our results suggest that the primary abiotic variable associated with Vallisneria americana in the UMR is light, not nutrients.

  5. Cyclone Tolerance in New World Arecaceae: Biogeographic Variation and Abiotic Natural Selection

    PubMed Central

    Griffith, M. Patrick; Noblick, Larry R.; Dowe, John L.; Husby, Chad E.; Calonje, Michael A.

    2008-01-01

    Background and Aims Consistent abiotic factors can affect directional selection; cyclones are abiotic phenomena with near-discrete geographic limits. The current study investigates selective pressure of cyclones on plants at the species level, testing for possible natural selection. Methods New World Arecaceae (palms) are used as a model system, as plants with monopodial, unbranched arborescent form are most directly affected by the selective pressure of wind load. Living specimens of known provenance grown at a common site were affected by the same cyclone. Data on percentage mortality were compiled and analysed in biogeographic and phylogenetic contexts. Key Results Palms of cyclone-prone provenance exhibited a much lower (one order of magnitude) range in cyclone tolerance, and significantly lower (P < 0·001) mean percentage mortality than collections from cyclone-free areas. Palms of cyclone-free provenance had much greater variation in tolerance, and significantly greater mean percentage mortality. A test for serial independence recovered no significant phylogenetic autocorrelation of percentage mortality. Conclusions Variation in cyclone tolerance in New World Arecaceae correlates with biogeography, and is not confounded with phylogeny. These results suggest natural selection of cyclone tolerance in cyclone-prone areas. PMID:18669575

  6. Influence of sky view factor on outdoor thermal environment and physiological equivalent temperature

    NASA Astrophysics Data System (ADS)

    He, Xiaodong; Miao, Shiguang; Shen, Shuanghe; Li, Ju; Zhang, Benzhi; Zhang, Ziyue; Chen, Xiujie

    2015-03-01

    Sky view factor (SVF), which is an indicator of urban canyon geometry, affects the surface energy balance, local air circulation, and outdoor thermal comfort. This study focused on a continuous and long-term meteorological observation system to investigate the effects of SVF on outdoor thermal conditions and physiological equivalent temperature (PET) in the central business district (CBD) of Beijing (which is located within Chaoyang District), specifically addressed current knowledge gaps for SVF-PET relationships in cities with typical continental/microthermal climates. An urban sub-domain scale model and the RayMan model were used to diagnose wind fields and to calculate SVF and long-term PET, respectively. Analytical results show that the extent of shading contributes to variations in thermal perception distribution. Highly shaded areas (SVF <0.3) typically exhibit less frequent hot conditions during summer, while enduring longer periods of cold discomfort in winter than moderately shaded areas (0.3< SVF <0.5) and slightly shaded areas (SVF >0.5), and vice versa. Because Beijing has a monsoon-influenced humid continental climate with hot summers and long, cold, windy, and dry winters, a design project that ideally provides moderate shading should be planned to balance hot discomfort in summer and cold discomfort in winter, which effectively prolongs the comfort periods in outdoor spaces throughout the entire year. This research indicate that climate zone characteristics, urban environmental conditions, and thermal comfort requirements of residents must be accounted for in local-scale scientific planning and design, i.e., for urban canyon streets and residential estates.

  7. Factors affecting quality of temperature models for the pre-appearance interval of forensically useful insects.

    PubMed

    Matuszewski, Szymon; Mądra, Anna

    2015-02-01

    In the case of many forensically important insects an interval preceding appearance of an insect stage on a corpse (called the pre-appearance interval or PAI) is strongly temperature-dependent. Accordingly, it was proposed to estimate PAI from temperature by using temperature models for PAI of particular insect species and temperature data specific for a given case. The quality of temperature models for PAI depends on the protocols for PAI field studies. In this article we analyze effects of sampling frequency and techniques, temperature data, as well as the size of a sample on the quality of PAI models. Models were created by using data from a largely replicated PAI field study, and their performance in estimation was tested with external body of PAI data. It was found that low frequency of insect sampling distinctly deteriorated temperature models for PAI. The effect of sampling techniques was clearly smaller. Temperature data from local weather station gave models of poor quality, however their retrospective correction clearly improved the models. Most importantly, current results demonstrate that sample size in PAI field studies may be substantially reduced, with no model deterioration. Samples consisting of 11-14 carcasses gave models of high quality, as long as the whole range of relevant temperatures was studied. Moreover, it was found that carcasses exposed in forests and carcasses exposed in early spring are particularly important, as they ensure that PAI data is collected at low temperatures. A preliminary best practice model for PAI field studies is given. PMID:25541074

  8. Abiotic Versus Biotic Weathering Of Olivine As Possible Biosignatures

    NASA Technical Reports Server (NTRS)

    Longazo, Teresa G.; Wentworth, Susan J.; Clemett, Simon J.; Southam, Gordon; McKay, David S.

    2001-01-01

    We are investigating the weathering of silicate minerals by both purely inorganic, and biologically mediated processes using field-emission scanning electron microscopy (FESEM) and energy dispersive x-ray spectroscopy (EDS). By resolving surface textures and chemical compositions of weathered surfaces at the sub-micron scale we hope to be able to distinguish abiotic from biotic weathering processes and so establish a new biosignature applicable to the study of astromaterials including but not limited to the Martian meteorites. Sterilized olivine grains (San Carlos, Arizona) no more than 1-2 mm in their longest dimension were optically assayed to be uniform in color and free of inclusions were selected as weathering subjects. Prior to all experiments surface morphologies and Fe/Mg ratios were determined for each grain using FE-SEM and EDS. Experiments were divided into two categories abiotic and biotic and were compared with "naturally" weathered samples. For the preliminary experiments, two trials (open and closed to the ambient laboratory environment) were performed under abiotic conditions, and three trials under biotic conditions (control, day 1 and day 2). The open system abiotic trials used sterile grains heated at 98 C and 200 C for both 24 and 48 hours in 1L double distilled de-ionized water. The closed system abiotic trials were conducted under the same conditions but in a sealed two layer steel/Teflon "bomb" apparatus. The biotic trials used sterile grains mounted in a flow-through device attached to a wellhead on the Columbia River aquifer. Several discolored, altered, grains were selected to document "natural" weathering surface textures for comparison with the experimental samples. Preliminary results indicate there are qualitative differences in weathered surface textures among all the designed experiments. The olivine grains in abiotic trials displayed etching, pitting, denticulate margins, dissolution and clay formation. The scale of the features

  9. Experimental investigation of the factors influencing temperature dependence of radiation-induced attenuation in optical fiber

    NASA Astrophysics Data System (ADS)

    Jin, Jing; Xu, Raomei; Liu, Jixun; Song, Ningfang

    2014-03-01

    The effects of transmission wavelength, total dose and light source power on temperature dependence of radiation-induced attenuation (RIA) in Ge-P co-doped fibers were investigated. Three fibers irradiated up to total dose of 100 Gy and 10,000 Gy were used as test samples. A test system for temperature dependence of RIA was built up. The influence of transmission wavelength, total dose and light power on temperature sensitivity and linearity of RIA in three irradiated fibers were researched. The test results show that temperature sensitivity and linearity of RIA in optical fibers could be improved by adjusting total dose and selecting transmission wavelength. The light source power does not have obvious influence on temperature sensitivity and linearity. The Ge-P co-doped fiber at 850 nm transmission wavelength with higher total dose is a very promising candidate for fiber-optic temperature sensor.

  10. Temperature-dependent magnetostriction as the key factor for martensite reorientation in magnetic field

    NASA Astrophysics Data System (ADS)

    L’vov, Victor A.; Kosogor, Anna

    2016-09-01

    The magnetic field application leads to spatially inhomogeneous magnetostriction of twinned ferromagnetic martensite. When the increasing field and magnetostrictive strain reach certain threshold values, the motion of twin boundaries and magnetically induced reorientation (MIR) of twinned martensite start. The MIR leads to giant magnetically induced deformation of twinned martensite. In the present article, the threshold field (TF) and temperature range of observability of MIR were calculated for the Ni–Mn–Ga martensite assuming that the threshold strain (TS) is temperature-independent. The calculations show that if the TS is of the order of 10‑4, the TF strongly depends on temperature and MIR can be observed only above the limiting temperature (~220 K). If the TS is of the order of 10‑6, the TF weakly depends on temperature and MIR can be observed at extremely low temperatures. The obtained theoretical results are in agreement with available experimental data.

  11. Profile correction to electron temperature and enhancement factor in soft x-ray pulse-height-analysis measurements in tokamaks

    SciTech Connect

    Sesnic, S.; Diesso, M.; Hill, K.; Holland, A.; Pohl, F.

    1988-04-01

    Because soft x-ray pulse-height-analysis (PHA) spectra contain chordal information, the electron temperature and the radiation intensity (enhancement factor) measurements do not represent the local values. Assuming that the profile Ansatz for the electron temperature and density is of the form n/sub eo/(1-(ra)/sup 2/)/sup ..cap alpha../ and kT/sub eo/(1--(ra)/sup 2/)/sup ..beta../, we obtain the correction factors for the electron temperature and the enhancement factor as a function of the profile coefficients ..cap alpha.. and ..beta.. and the energy at which the evaluation was made. The corrected values of the temperature are typically between 1 to 10% higher than the values derived from the raw chordal spectra. We also correct the measured radiation intensity for the profile effects. Finally, the spectrum distortion due to pulse pile-up effects is evaluated. A set of curves is given from which the distortion of the spectrum can be obtained, if the electron temperature, the Be or Al filter thickness, and the electronic parameters of the acquisition system are known. 7 refs., 23 figs.

  12. Survival of manure-borne and fecal coliforms in soil: temperature dependence as affected by site-specific factors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding pathogenic and indicator bacteria survival in soils is essential for assessing the potential of microbial contamination of water and produce, and making appropriate management decisions. The objective of this work was to evaluate effects of soil and management factors on temperature de...

  13. Photo-oxidative stress markers as a measure of abiotic stress-induced leaf senescence: advantages and limitations.

    PubMed

    Pintó-Marijuan, Marta; Munné-Bosch, Sergi

    2014-07-01

    Inside chloroplasts, several abiotic stresses (including drought, high light, salinity, or extreme temperatures) induce a reduction in CO2 assimilation rates with a consequent increase in reactive oxygen species (ROS) production, ultimately leading to leaf senescence and yield loss. Photo-oxidation processes should therefore be mitigated to prevent leaf senescence, and plants have evolved several mechanisms to either prevent the formation of ROS or eliminate them. Technology evolution during the past decade has brought faster and more precise methodologies to quantify ROS production effects and damage, and the capacities of plants to withstand oxidative stress. Nevertheless, it is very difficult to disentangle photo-oxidative processes that bring leaf defence and acclimation, from those leading to leaf senescence (and consequently death). It is important to avoid the mistake of discussing results on leaf extracts as being equivalent to chloroplast extracts without taking into account that other organelles, such as peroxisomes, mitochondria, or the apoplast also significantly contribute to the overall ROS production within the cell. Another important aspect is that studies on abiotic stress-induced leaf senescence in crops do not always include a time-course evolution of studied processes, which limits our knowledge about what photo-oxidative stress processes are required to irreversibly induce the senescence programme. This review will summarize the current technologies used to evaluate the extent of photo-oxidative stress in plants, and discuss their advantages and limitations in characterizing abiotic stress-induced leaf senescence in crops. PMID:24683180

  14. Improvement of lipid production in the marine strains Alexandrium minutum and Heterosigma akashiwo by utilizing abiotic parameters.

    PubMed

    Fuentes-Grünewald, C; Garcés, E; Alacid, E; Sampedro, N; Rossi, S; Camp, J

    2012-01-01

    Two different strains of microalgae, one raphidophyte and one dinoflagellate, were tested under different abiotic conditions with the goal of enhancing lipid production. Whereas aeration was crucial for biomass production, nitrogen deficiency and temperature were found to be the main abiotic parameters inducing the high-level cellular accumulation of neutral lipids. Net neutral lipid production and especially triacylglycerol (TAG) per cell were higher in microalgae (>200% in Alexandrium minutum, and 30% in Heterosigma akashiwo) under treatment conditions (25°C; 330 μM NaNO(3)) than under control conditions (20°C; 880 μM NaNO(3)). For both algal species, oil production (free fatty acids plus TAG fraction) was also higher under treatment conditions (57 mg L(-1) in A. minutum and 323 mg L(-1) in H. akashiwo). Despite the increased production and accumulation of lipids in microalgae, the different conditions did not significantly change the fatty acids profiles of the species analyzed. These profiles consisted of saturated fatty acids (SAFA) and polyunsaturated fatty acids (PUFA) in significant proportions. However, during the stationary phase, the concentrations per cell of some PUFAs, especially arachidonic acid (C20:4n6), were higher in treated than in control algae. These results suggest that the adjustment of abiotic parameters is a suitable and one of the cheapest alternatives to obtain sufficient quantities of microalgal biomass, with high oil content and minimal changes in the fatty acid profile of the strains under consideration. PMID:21766212

  15. Thermodynamic Potential for the Abiotic Synthesis of Adenine, Cytosine, Guanine, Thymine, Uracil, Ribose, and Deoxyribose in Hydrothermal Systems

    NASA Astrophysics Data System (ADS)

    Larowe, Douglas E.; Regnier, Pierre

    2008-10-01

    The thermodynamic potential for the abiotic synthesis of the five common nucleobases (adenine, cytosine, guanine, thymine, and uracil) and two monosaccharides (ribose and deoxyribose) from formaldehyde and hydrogen cyanide has been quantified under temperature, pressure, and bulk composition conditions that are representative of hydrothermal systems. The activities of the precursor molecules (formaldehyde and hydrogen cyanide) required to evaluate the thermodynamics of biomolecule synthesis were computed using the concentrations of aqueous N2, CO, CO2 and H2 reported in the modern Rainbow hydrothermal system. The concentrations of precursor molecules that can be synthesized are strongly dependent on temperature with larger concentrations prevailing at lower temperatures. Similarly, the thermodynamic drive to synthesize nucleobases, ribose and deoxyribose varies considerably as a function of temperature: all of the biomolecules considered in this study are thermodynamically favored to be synthesized throughout the temperature range from 0°C to between 150°C and 250°C, depending on the biomolecule. Furthermore, activity diagrams have been generated to illustrate that activities in the range of 10-2- 10-6 for nucleobases, ribose and deoxyribose can be in equilibrium with a range of precursor molecule activities at 150°C and 500 bars. The results presented here support the notion that hydrothermal systems could have played a fundamental role in the origin of life, and can be used to plan and constrain experimental investigation of the abiotic synthesis of nucleic-acid related biomolecules.

  16. The net effect of abiotic conditions and biotic interactions in a semi-arid ecosystem NE Spain: implications for the management and restoration.

    NASA Astrophysics Data System (ADS)

    Pueyo, Yolanda; Arroyo, Antonio I.; Saiz, Hugo; Alados, Concepción L.

    2014-05-01

    Degradation in arid and semiarid lands can be irreversible without human intervention, due to a positive plant-soil feedback where the loss of vegetation cover leads to soil degradation, which in turn hampers plant establishment. Human intervention in restoration actions usually involves the amendment of the degraded abiotic conditions, revegetation of bare areas, or both. However, abiotic amelioration is often expensive and too intrusive, and revegetation is not successful in many cases. Biotic interactions between plants, and more specifically facilitation by a "nurse" plant, have been proposed as a new via to take profit of improved abiotic conditions without intervention, and to increase the success rate of revegetation actions. But "nurse" plants can also interfere with others (i.e. by competition for resources or the release of allelopathic compounds), and the net balance between facilitation and interference could depend on plant types involved. We present recent observational and experimental studies performed in the semiarid ecosystems of the Middle Ebro Valley (NE Spain) about the role of abiotic conditions and biotic interactions in the productivity, dynamics and diversity of plant communities under different stress conditions (aridity and grazing). We found that all plant types studied (shrubs and perennial grasses) improved abiotic conditions (soil temperature and water availability for plants) with respect to open areas. However, only some shrubs (mainly Salsola vermiculata) had a positive net balance in the biotic interactions between plants, while other shrubs (Artemisia herba-alba) and perennial grasses (Lygeum spartum) showed interference with other plants. Moreover, the net balance between facilitation and interference among plants in the community shifted from competitive to neutral or from neutral to facilitative with increasing aridity. Grazing status did not strongly change the net biotic interactions between plants. Our results suggest that

  17. SUMMER STREAM TEMPERATURES, JUVENILE COHO CONDITION FACTORS AND BLACK SPOT INFECTION IN THE OREGON COAST RANGE

    EPA Science Inventory

    We monitored stream temperatures at 35 locations throughout the West Fork Smith River watershed in the Oregon Coast Range during the summer of 2002. Between July 24 and August 24, maximum seven-day moving average high daily temperatures ranged from 21.8 C near the catchment's mo...

  18. A hypothesis about factors that affect maximum stream temperatures across montane landscapes

    USGS Publications Warehouse

    Isaak, D.J.; Hubert, W.A.

    2001-01-01

    Temperature is an important variable structuring lotic biotas, but little is known about how montane landscapes function to determine stream temperatures. We developed an a priori hypothesis that was used to predict how watershed elements would interact to affect stream temperatures. The hypothesis was tested in a series of path analyses using temperature data from 26 sites on second-order to fourth-order streams across a fifth-order Rocky Mountain watershed. Based on the performance of the first hypothesis, two revised versions of the hypothesis were developed and tested that proved to be more accurate than the original hypothesis. The most plausible of the revised hypotheses accounted for 82 percent of the variation in maximum stream temperature, had a predicted data structure that did not deviate from the empirical data structure, and was the most parsimonious. The final working hypothesis suggested that stream temperature maxima were directly controlled by a large negative effect from mean basin elevation (direct effect = -0.57, p < 0.01) and smaller effects from riparian tree abundance (direct effect = -0.28, p = 0.03), and cattle density (direct effect = 0.24, p = 0.05). Watershed slope, valley constraint, and the abundance of grass across a watershed also affected temperature maxima, but these effects were indirect and mediated through cattle density and riparian trees. Three variables included in the a priori hypothesis - watershed aspect, stream width, and watershed size - had negligible effects on maximum stream temperatures and were omitted from the final working hypothesis.

  19. Effect of design factors on surface temperature and wear in disk brakes

    NASA Technical Reports Server (NTRS)

    Santini, J. J.; Kennedy, F. E.; Ling, F. F.

    1976-01-01

    The temperatures, friction, wear and contact conditions that occur in high energy disk brakes are studied. Surface and near surface temperatures were monitored at various locations in a caliper disk brake during drag type testing, with friction coefficient and wear rates also being determined. The recorded transient temperature distributions in the friction pads and infrared photographs of the rotor disk surface both showed that contact at the friction surface was not uniform, with contact areas constantly shifting due to nonuniform thermal expansion and wear. The effect of external cooling and of design modifications on friction, wear and temperatures was also investigated. It was found that significant decreases in surface temperature and in wear rate can be achieved without a reduction in friction either by slotting the contacting face of the brake pad or by modifying the design of the pad support to improve pad compliance. Both design changes result in more uniform contact conditions on the friction surface.

  20. Dominant factors affecting temperature rise in simulations of human thermoregulation during RF exposure.

    PubMed

    Laakso, Ilkka; Hirata, Akimasa

    2011-12-01

    Numerical models of the human thermoregulatory system can be used together with realistic voxel models of the human anatomy to simulate the body temperature increases caused by the power absorption from radio-frequency electromagnetic fields. In this paper, the Pennes bioheat equation with a thermoregulatory model is used for calculating local peak temperatures as well as the body-core-temperature elevation in a realistic human body model for grounded plane-wave exposures at frequencies 39, 800 and 2400 MHz. The electromagnetic power loss is solved by the finite-difference time-domain (FDTD) method, and the discretized bioheat equation is solved by the geometric multigrid method. Human thermoregulatory models contain numerous thermophysiological and computational parameters--some of which may be subject to considerable uncertainty--that affect the simulated core and local temperature elevations. The goal of this paper is to find how greatly the computed temperature is influenced by changes in various modelling parameters, such as the skin blood flow rate, models for vasodilation and sweating, and clothing and air movement. The results show that the peak temperature rises are most strongly affected by the modelling of tissue blood flow and its temperature dependence, and mostly unaffected by the central control mechanism for vasodilation and sweating. Almost the opposite is true for the body-core-temperature rise, which is however typically greatly lower than the peak temperature rise. It also seems that ignoring the thermoregulation and the blood temperature increase is a good approximation when the local 10 g averaged specific absorption rate is smaller than 10 W kg(-1). PMID:22080753

  1. Dominant factors affecting temperature rise in simulations of human thermoregulation during RF exposure

    NASA Astrophysics Data System (ADS)

    Laakso, Ilkka; Hirata, Akimasa

    2011-12-01

    Numerical models of the human thermoregulatory system can be used together with realistic voxel models of the human anatomy to simulate the body temperature increases caused by the power absorption from radio-frequency electromagnetic fields. In this paper, the Pennes bioheat equation with a thermoregulatory model is used for calculating local peak temperatures as well as the body-core-temperature elevation in a realistic human body model for grounded plane-wave exposures at frequencies 39, 800 and 2400 MHz. The electromagnetic power loss is solved by the finite-difference time-domain (FDTD) method, and the discretized bioheat equation is solved by the geometric multigrid method. Human thermoregulatory models contain numerous thermophysiological and computational parameters—some of which may be subject to considerable uncertainty—that affect the simulated core and local temperature elevations. The goal of this paper is to find how greatly the computed temperature is influenced by changes in various modelling parameters, such as the skin blood flow rate, models for vasodilation and sweating, and clothing and air movement. The results show that the peak temperature rises are most strongly affected by the modelling of tissue blood flow and its temperature dependence, and mostly unaffected by the central control mechanism for vasodilation and sweating. Almost the opposite is true for the body-core-temperature rise, which is however typically greatly lower than the peak temperature rise. It also seems that ignoring the thermoregulation and the blood temperature increase is a good approximation when the local 10 g averaged specific absorption rate is smaller than 10 W kg-1.

  2. Temperature dependence of the lattice parameter and Debye-Waller factor of a high-chromium pressure-vessel steel

    NASA Astrophysics Data System (ADS)

    Sumin, V. V.; Simkin, V. G.; Sheverev, S. G.; Leont'eva-Smirnova, M. V.; Chernov, V. M.

    2009-12-01

    The method of thermal neutron diffraction has been used to study samples of the EK-181 steel at temperatures of 15 to 973 K in an IBR-2 reactor (Joint Institute for Nuclear Research (JINR)). Temperature dependences of the lattice parameter, internal textural stresses (of the third kind), and the Debye-Waller factor of this steel have been calculated from diffraction spectra by the Rietveld method. It has been found that at low temperatures the temperature dependence of the lattice parameter in the EK-181 steel (RUSFER EK-181) differs from the corresponding dependence in pure iron and binary iron-chromium alloys containing 12 and 16% Cr. Also, a broadening of the ( 200) reflection has been observed in the diffraction spectra of the EK-181 steel and the Fe-12Cr alloy, while it is not detected in the spectra of Fe-16Cr and pure iron.

  3. Abiotic stressors and stress responses: What commonalities appear between species across biological organization levels?

    PubMed

    Sulmon, Cécile; van Baaren, Joan; Cabello-Hurtado, Francisco; Gouesbet, Gwenola; Hennion, Françoise; Mony, Cendrine; Renault, David; Bormans, Myriam; El Amrani, Abdelhak; Wiegand, Claudia; Gérard, Claudia

    2015-07-01

    Organisms are regularly subjected to abiotic stressors related to increasing anthropogenic activities, including chemicals and climatic changes that induce major stresses. Based on various key taxa involved in ecosystem functioning (photosynthetic microorganisms, plants, invertebrates), we review how organisms respond and adapt to chemical- and temperature-induced stresses from molecular to population level. Using field-realistic studies, our integrative analysis aims to compare i) how molecular and physiological mechanisms related to protection, repair and energy allocation can impact life history traits of stressed organisms, and ii) to what extent trait responses influence individual and population responses. Common response mechanisms are evident at molecular and cellular scales but become rather difficult to define at higher levels due to evolutionary distance and environmental complexity. We provide new insights into the understanding of the impact of molecular and cellular responses on individual and population dynamics and assess the potential related effects on communities and ecosystem functioning. PMID:25813422

  4. Carbonyl sulfide produced by abiotic thermal and photodegradation of soil organic matter from wheat field substrate

    NASA Astrophysics Data System (ADS)

    Whelan, Mary E.; Rhew, Robert C.

    2015-01-01

    sulfide (COS) is a reduced sulfur gas that is taken up irreversibly in plant leaves proportionally with CO2, allowing its potential use as a tracer for gross primary production. Recently, wheat field soil at the Southern Great Plains Atmospheric Radiation Measurement site in Lamont, Oklahoma, was found to be a measureable source of COS to the atmosphere. To understand the mechanism of COS production, soil and root samples were collected from the site and incubated in the laboratory over a range of temperatures (15-34°C) and light conditions (light and dark). Samples exhibited mostly COS net uptake from the atmosphere in dark and cool (<22-25°C) trials. COS emission was observed during dark incubations at high temperatures (>25°C), consistent with field observations, and at a lower temperature (19°C) when a full spectrum lamp (max wavelength 600 nm) was applied. Sterilized soil and root samples yielded only COS production that increased with temperature, supporting the hypothesis that (a) COS production in these samples is abiotic, (b) production is directly influenced by temperature and light, and (c) some COS consumption in soil and root samples is biotic.

  5. Resource supply overrides temperature as a controlling factor of marine phytoplankton growth.

    PubMed

    Marañón, Emilio; Cermeño, Pedro; Huete-Ortega, María; López-Sandoval, Daffne C; Mouriño-Carballido, Beatriz; Rodríguez-Ramos, Tamara

    2014-01-01

    The universal temperature dependence of metabolic rates has been used to predict how ocean biology will respond to ocean warming. Determining the temperature sensitivity of phytoplankton metabolism and growth is of special importance because this group of organisms is responsible for nearly half of global primary production, sustains most marine food webs, and contributes to regulate the exchange of CO2 between the ocean and the atmosphere. Phytoplankton growth rates increase with temperature under optimal growth conditions in the laboratory, but it is unclear whether the same degree of temperature dependence exists in nature, where resources are often limiting. Here we use concurrent measurements of phytoplankton biomass and carbon fixation rates in polar, temperate and tropical regions to determine the role of temperature and resource supply in controlling the large-scale variability of in situ metabolic rates. We identify a biogeographic pattern in phytoplankton metabolic rates, which increase from the oligotrophic subtropical gyres to temperate regions and then coastal waters. Variability in phytoplankton growth is driven by changes in resource supply and appears to be independent of seawater temperature. The lack of temperature sensitivity of realized phytoplankton growth is consistent with the limited applicability of Arrhenius enzymatic kinetics when substrate concentrations are low. Our results suggest that, due to widespread resource limitation in the ocean, the direct effect of sea surface warming upon phytoplankton growth and productivity may be smaller than anticipated. PMID:24921945

  6. Response of plant tundra communities to changes in abiotic and biotic environments: Importance of the temporal dimension

    NASA Astrophysics Data System (ADS)

    Saccone, P.; Virtanen, R.

    2015-12-01

    Understanding of ecosystem response to changing environment have been improved by the convergence of observational and experimental approaches that allow disentangling mechanisms involved and large scale subsequent patterns. However, such approaches often face context-dependence of underlying processes, and a major challenge of community ecology is to deepen our understanding of this context-dependency for reliable upscaling. Here we used the results from several transplant experiments of heath communities in the Northern Fennoscandian during the last two decades to investigate the relative importance of abiotic and biotic drivers and the plant functional response. The plant community composition of blocks of heath vegetation from diverse origins transplanted in contrasted abiotic and biotic conditions was monitored from 6 to 23 years depending on the design. Considering both abiotic severity and biotic environment, the transplantation along altitudinal gradient constituted major habitat perturbation, in particular for communities from the mountain tundra vulnerable to strong functional shift. In addition, the joint effects of multiple drivers associated to grazing pressure and abiotic micro heterogeneity resulted in divergent community in the long-term. However, the different factors operated on different temporal scales. The vegetation depending on their origin and functional type also showed contrasted patterns from immediate and transient response to strong biological inertia. Our results reveal the potential for alternative response of plant communities depending on the interplay between the multiple drivers and the functional attributes of the vegetation. This interplay should drive plant communities toward divergent alternative states, but our ability to extrapolate longer-term trajectories from partial dynamics is challenged by the temporal differences in drivers pressure and plant response. The responses to manipulation appear as successional processes and

  7. Pathways for abiotic organic synthesis at submarine hydrothermal fields

    PubMed Central

    McDermott, Jill M.; Seewald, Jeffrey S.; German, Christopher R.; Sylva, Sean P.

    2015-01-01

    Arguments for an abiotic origin of low-molecular weight organic compounds in deep-sea hot springs are compelling owing to implications for the sustenance of deep biosphere microbial communities and their potential role in the origin of life. Theory predicts that warm H2-rich fluids, like those emanating from serpentinizing hydrothermal systems, create a favorable thermodynamic drive for the abiotic generation of organic compounds from inorganic precursors. Here, we constrain two distinct reaction pathways for abiotic organic synthesis in the natural environment at the Von Damm hydrothermal field and delineate spatially where inorganic carbon is converted into bioavailable reduced carbon. We reveal that carbon transformation reactions in a single system can progress over hours, days, and up to thousands of years. Previous studies have suggested that CH4 and higher hydrocarbons in ultramafic hydrothermal systems were dependent on H2 generation during active serpentinization. Rather, our results indicate that CH4 found in vent fluids is formed in H2-rich fluid inclusions, and higher n-alkanes may likely be derived from the same source. This finding implies that, in contrast with current paradigms, these compounds may form independently of actively circulating serpentinizing fluids in ultramafic-influenced systems. Conversely, widespread production of formate by ΣCO2 reduction at Von Damm occurs rapidly during shallow subsurface mixing of the same fluids, which may support anaerobic methanogenesis. Our finding of abiogenic formate in deep-sea hot springs has significant implications for microbial life strategies in the present-day deep biosphere as well as early life on Earth and beyond. PMID:26056279

  8. Pathways for abiotic organic synthesis at submarine hydrothermal fields.

    PubMed

    McDermott, Jill M; Seewald, Jeffrey S; German, Christopher R; Sylva, Sean P

    2015-06-23

    Arguments for an abiotic origin of low-molecular weight organic compounds in deep-sea hot springs are compelling owing to implications for the sustenance of deep biosphere microbial communities and their potential role in the origin of life. Theory predicts that warm H2-rich fluids, like those emanating from serpentinizing hydrothermal systems, create a favorable thermodynamic drive for the abiotic generation of organic compounds from inorganic precursors. Here, we constrain two distinct reaction pathways for abiotic organic synthesis in the natural environment at the Von Damm hydrothermal field and delineate spatially where inorganic carbon is converted into bioavailable reduced carbon. We reveal that carbon transformation reactions in a single system can progress over hours, days, and up to thousands of years. Previous studies have suggested that CH4 and higher hydrocarbons in ultramafic hydrothermal systems were dependent on H2 generation during active serpentinization. Rather, our results indicate that CH4 found in vent fluids is formed in H2-rich fluid inclusions, and higher n-alkanes may likely be derived from the same source. This finding implies that, in contrast with current paradigms, these compounds may form independently of actively circulating serpentinizing fluids in ultramafic-influenced systems. Conversely, widespread production of formate by ΣCO2 reduction at Von Damm occurs rapidly during shallow subsurface mixing of the same fluids, which may support anaerobic methanogenesis. Our finding of abiogenic formate in deep-sea hot springs has significant implications for microbial life strategies in the present-day deep biosphere as well as early life on Earth and beyond. PMID:26056279

  9. Temperature dependent barrier height and ideality factor of electrodeposited n-CdSe/Cu Schottky barrier diode

    SciTech Connect

    Mahato, S. Shiwakoti, N.; Kar, A. K.

    2015-06-24

    This article reports the measurement of temperature-dependent barrier height and ideality factor of n-CdSe/Cu Schottky barrier diode. The Cadmium Selenide (CdSe) thin films have been deposited by simple electrodeposition technique. The XRD measurements ravels the deposited single phase CdSe films are highly oriented on (002) plane and the average particle size has been calculated to be ~18 nm. From SEM characterization, it is clear that the surface of CdSe thin films are continuous, homogeneous and the film is well adhered to the substrate and consists of fine grains which are irregular in shape and size. Current-Voltage characteristics have been measured at different temperatures in the range (298 K – 353 K). The barrier height and ideality factor are found to be strongly temperature dependent. The inhomogenious barrier height increases and ideality factor decreases with increase in temperature. The expectation value has been calculated and its value is 0.30 eV.

  10. Model Comparison for Abiotic versus Biotic Pollen Dispersal.

    PubMed

    Foster, Erich L; Chan, David M; Dyer, Rodney J

    2016-10-01

    An agent-based model with a correlated random walk is used to explore pollination within a forest. For abiotic dispersal, say via the wind, we use a purely random walk where there is no correlation between consecutive steps and for biotic dispersal, say via insect, we use a moderate or highly correlated random walk. In particular, we examine the differences in a number of biological measurement between a purely random walk and a correlated random walk in terms of gene dispersal in low and high plant densities. PMID:27550704

  11. Coupled Abiotic-Biotic Degradation of Bisphenol A

    NASA Astrophysics Data System (ADS)

    Im, J.; Prevatte, C.; Campagna, S. R.; Loeffler, F.

    2014-12-01

    Bisphenol A (BPA) is a ubiquitous environmental contaminant with weak estrogenic activity. BPA is readily biodegradable with oxygen available, but is recalcitrant to microbial degradation under anoxic conditions. However, BPA is susceptible to abiotic transformation under anoxic conditions. To better understand the fate of BPA in anoxic environments, the kinetics of BPA transformation by manganese oxide (d-MnO2) were investigated. BPA was rapidly transformed by MnO2 with a pseudo-first-order rate constant of 0.413 min-1. NMR and LC-MS analyses identified 4-hydroxycumyl alcohol (HCA) as a major intermediate. Up to 64% of the initial amount of BPA was recovered as HCA within 5 min, but the conversion efficiency decreased with time, suggesting that HCA was further degraded by MnO2. Further experiments confirmed that HCA was also susceptible to transformation by MnO2, albeit at 5-fold lower rates than BPA transformation. Mass balance approaches suggested that HCA was the major BPA transformation intermediate, but other compounds may also be formed. The abiotic transformation of BPA by MnO2 was affected by pH, and 10-fold higher transformation rates were observed at pH 4.5 than at pH 10. Compared to BPA, HCA has a lower octanol-water partitioning coefficient (Log Kow) of 0.76 vs 2.76 for BPA and a higher aqueous solubility of 2.65 g L-1 vs 0.31 g L-1 for BPA, suggesting higher mobility of HCA in the environment. Microcosms established with freshwater sediment materials collected from four geographically distinct locations and amended with HCA demonstrated rapid HCA biodegradation under oxic, but not under anoxic conditions. These findings suggest that BPA is not inert under anoxic conditions and abiotic reactions with MnO2 generate HCA, which has increased mobility and is susceptible to aerobic degradation. Therefore, coupled abiotic-biotic processes can affect the fate and longevity of BPA in terrestrial environments.

  12. May Cyclic Nucleotides Be a Source for Abiotic RNA Synthesis?

    NASA Astrophysics Data System (ADS)

    Costanzo, Giovanna; Pino, Samanta; Botta, Giorgia; Saladino, Raffaele; di Mauro, Ernesto

    2011-12-01

    Nucleic bases are obtained by heating formamide in the presence of various catalysts. Formamide chemistry also allows the formation of acyclonucleosides and the phosphorylation of nucleosides in every possible position, also affording 2',3' and 3',5' cyclic forms. We have reported that 3',5' cyclic GMP and 3',5' cyclic AMP polymerize in abiotic conditions yielding short oligonucleotides. The characterization of this reaction is being pursued, several of its parameters have been determined and experimental caveats are reported. The yield of non-enzymatic polymerization of cyclic purine nucleotides is very low. Polymerization is strongly enhanced by the presence of base-complementary RNA sequences.

  13. Tomato plants acclimate better to elevated temperature and high light than to treatment with each factor separately.

    PubMed

    Gerganova, Milena; Popova, Antoaneta V; Stanoeva, Daniela; Velitchkova, Maya

    2016-07-01

    The influence of two factors - high temperature and high light intensity, acting separately or simultaneously on the pigment composition, fluorescent characteristics, membrane integrity and synthesis of protective substances was investigated in tomato plants (Solanum lycopersicum cv. M 82). Moderate elevated temperatures (38/29 °C) were applied under optimum or high light intensity for 2 and 6 days and after that the plants are allowed to recover for 5 days at optimum conditions. Parameters of chlorophyll fluorescence were used to evaluate the alterations of photosystem I and photosystem II activity and malondialdehyde content was determined as a measure of stress-induced peroxidation of membrane lipids. The response of treated plants to high light and elevated temperature was estimated by analyzing the accumulation of anthocyanins. Both stress factors exhibit different impact on studied parameters - high light intensity influences considerably quantum yield of photosystem II and photochemical quenching that is compensated to some extent when applied at elevated temperature. High temperature reduces strongly non-photochemical quenching. Data obtained show that after two days under particular conditions, the plants tend to acclimate, but this is achieved after longer treatment - 6 days. During the recovery period the activity of photosystem I and the quantum yield of photosystem II recover almost completely, while the values of non-photochemical quenching although slightly higher, did not reach the levels at the beginning of treatment. PMID:27038602

  14. Lattice dynamical calculations of anisotropic temperature factors of atoms in quartz, and the structure of β-quartz

    NASA Astrophysics Data System (ADS)

    Kihara, Kuniaki

    1993-02-01

    Temperature factors for oxygen and silicon atoms in β-quartz were calculated on a Born-von Karman lattice dynamical model of an ordered structure. The calculated thermal ellipsoids were in excellent agreements with those of the previous structure refinements of the order model, for both magnitudes and orientations of the principal axes. The temperature factors are contributed mainly by the soft optic modes in Γ-M and the lowest-lying acoustic modes along Γ-A, which are also strongly temperature-dependent. The cusp-shaped temperature dependence of mean square displacements, , of oxygen atom, observed previously around the α- β transition, are resulted from the softening of these modes. The temperature-dependent modes in Γ-A were also found to cause diffuse scattering extending along ±c* of the fourth hexagon of the hk0 reciprocal lattice plane. The negative expansion known in β-quartz were interpreted in terms of asymmetrical forces exerting on oxygen atoms in Si-O-Si bending modes. In β-quartz, librational motions of oxygen atoms around Si-Si lines with large amplitudes, whose center is just on the β-position of high symmetry, must be possible under the condition that bending tetrahedral O-Si-O angles is energetically more favourable than compressing or stretching Si-O bonds.

  15. Abiotic-biotic characterization of Pt/Ir microelectrode arrays in chronic implants.

    PubMed

    Prasad, Abhishek; Xue, Qing-Shan; Dieme, Robert; Sankar, Viswanath; Mayrand, Roxanne C; Nishida, Toshikazu; Streit, Wolfgang J; Sanchez, Justin C

    2014-01-01

    Pt/Ir electrodes have been extensively used in neurophysiology research in recent years as they provide a more inert recording surface as compared to tungsten or stainless steel. While floating microelectrode arrays (FMA) consisting of Pt/Ir electrodes are an option for neuroprosthetic applications, long-term in vivo functional performance characterization of these FMAs is lacking. In this study, we have performed comprehensive abiotic-biotic characterization of Pt/Ir arrays in 12 rats with implant periods ranging from 1 week up to 6 months. Each of the FMAs consisted of 16-channel, 1.5 mm long, and 75 μm diameter microwires with tapered tips that were implanted into the somatosensory cortex. Abiotic characterization included (1) pre-implant and post-explant scanning electron microscopy (SEM) to study recording site changes, insulation delamination and cracking, and (2) chronic in vivo electrode impedance spectroscopy. Biotic characterization included study of microglial responses using a panel of antibodies, such as Iba1, ED1, and anti-ferritin, the latter being indicative of blood-brain barrier (BBB) disruption. Significant structural variation was observed pre-implantation among the arrays in the form of irregular insulation, cracks in insulation/recording surface, and insulation delamination. We observed delamination and cracking of insulation in almost all electrodes post-implantation. These changes altered the electrochemical surface area of the electrodes and resulted in declining impedance over the long-term due to formation of electrical leakage pathways. In general, the decline in impedance corresponded with poor electrode functional performance, which was quantified via electrode yield. Our abiotic results suggest that manufacturing variability and insulation material as an important factor contributing to electrode failure. Biotic results show that electrode performance was not correlated with microglial activation (neuroinflammation) as we were able

  16. Abiotic-biotic characterization of Pt/Ir microelectrode arrays in chronic implants

    PubMed Central

    Prasad, Abhishek; Xue, Qing-Shan; Dieme, Robert; Sankar, Viswanath; Mayrand, Roxanne C.; Nishida, Toshikazu; Streit, Wolfgang J.; Sanchez, Justin C.

    2014-01-01

    Pt/Ir electrodes have been extensively used in neurophysiology research in recent years as they provide a more inert recording surface as compared to tungsten or stainless steel. While floating microelectrode arrays (FMA) consisting of Pt/Ir electrodes are an option for neuroprosthetic applications, long-term in vivo functional performance characterization of these FMAs is lacking. In this study, we have performed comprehensive abiotic-biotic characterization of Pt/Ir arrays in 12 rats with implant periods ranging from 1 week up to 6 months. Each of the FMAs consisted of 16-channel, 1.5 mm long, and 75 μm diameter microwires with tapered tips that were implanted into the somatosensory cortex. Abiotic characterization included (1) pre-implant and post-explant scanning electron microscopy (SEM) to study recording site changes, insulation delamination and cracking, and (2) chronic in vivo electrode impedance spectroscopy. Biotic characterization included study of microglial responses using a panel of antibodies, such as Iba1, ED1, and anti-ferritin, the latter being indicative of blood-brain barrier (BBB) disruption. Significant structural variation was observed pre-implantation among the arrays in the form of irregular insulation, cracks in insulation/recording surface, and insulation delamination. We observed delamination and cracking of insulation in almost all electrodes post-implantation. These changes altered the electrochemical surface area of the electrodes and resulted in declining impedance over the long-term due to formation of electrical leakage pathways. In general, the decline in impedance corresponded with poor electrode functional performance, which was quantified via electrode yield. Our abiotic results suggest that manufacturing variability and insulation material as an important factor contributing to electrode failure. Biotic results show that electrode performance was not correlated with microglial activation (neuroinflammation) as we were able

  17. Factors affecting temperature variation and habitat use in free-ranging diamondback terrapins.

    PubMed

    Akins, C D; Ruder, C D; Price, S J; Harden, L A; Gibbons, J W; Dorcas, M E

    2014-08-01

    Measuring the thermal conditions of aquatic reptiles with temperature dataloggers is a cost-effective way to study their behavior and habitat use. Temperature dataloggers are a particularly useful and informative approach to studying organisms such as the estuarine diamondback terrapin (Malaclemys terrapin) that inhabits a dynamic environment often inaccessible to researchers. We used carapace-mounted dataloggers to measure hourly carapace temperature (Tc) of free-ranging terrapins in South Carolina from October 2007 to 2008 to examine the effects of month, sex, creek site, and tide on Tc and to determine the effects of month, sex, and time of day on terrapin basking frequency. Simultaneous measurements of environmental temperatures (Te; shallow mud, deep mud, water) allowed us to make inferences about terrapin microhabitat use. Terrapin Tc differed significantly among months and creek and between sexes. Terrapin microhabitat use also varied monthly, with shallow mud temperature being the best predictor of Tc November-March and water temperature being the best predictor of Tc April-October. Terrapins basked most frequently in spring and fall and males basked more frequently than females. Our study contributes to a fuller understanding of terrapin thermal biology and provides support for using dataloggers to investigate behavior and habitat use of aquatic ectotherms inhabiting dynamic environments. PMID:25086975

  18. Metabolite profiling and transcript analysis reveal specificities in the response of a berry derived cell culture to abiotic stresses

    PubMed Central

    Ayenew, Biruk; Degu, Asfaw; Manela, Neta; Perl, Avichai; Shamir, Michal O.; Fait, Aaron

    2015-01-01

    As climate changes, there is a need to understand the expected effects on viticulture. In nature, stresses exist in a combined manner, hampering the elucidation of the effect of individual cues on grape berry metabolism. Cell suspension culture originated from pea-size Gamy Red grape berry was used to harness metabolic response to high light (HL; 2500 μmol m-2s-1), high temperature (HT; 40°C) and their combination in comparison to 25°C and 100 μmol m-2s-1 under controlled condition. When LC–MS and GC–MS based metabolite profiling was implemented and integrated with targeted RT-qPCR transcript analysis specific responses were observed to the different cues. HL enhanced polyphenol metabolism while HT and its combination with HL induced amino acid and organic acid metabolism with additional effect on polyphenols. The trend of increment in TCA cycle genes like ATCs, ACo1, and IDH in the combined treatment might support the observed increment in organic acids, GABA shunt, and their derivatives. The apparent phenylalanine reduction with polyphenol increment under HL suggests enhanced fueling of the precursor toward the downstream phenylpropanoid pathway. In the polyphenol metabolism, a differential pattern of expression of flavonoid 3′,5′ hydroxylase and flavonoid 3′ hydroxylase was observed under high light (HL) and combined cues which were accompanied by characteristic metabolite profiles. HT decreased glycosylated cyanidin and peonidin forms while the combined cues increased acetylated and coumarylated peonidin forms. Transcription factors regulating anthocyanin metabolism and their methylation, MYB, OMT, UFGT, and DFR, were expressed differentially among the treatments, overall in agreement with the metabolite profiles. Taken together these data provide insights into the coordination of central and secondary metabolism in relation to multiple abiotic stresses. PMID:26442042

  19. Abiotic effects on effluent dissolved organic nitrogen along an estuarine transect.

    PubMed

    Funkey, Carolina P; Latour, Robert J; Bronk, Deborah A

    2015-03-01

    Biological nutrient removal is a process commonly used in water resource recovery facilities to reduce dissolved inorganic nitrogen (DIN) concentrations in effluent; this process is less effective at removing all of the effluent dissolved organic nitrogen (EDON). The goal of this study was to investigate the fate of EDON after it undergoes the disinfection process and enters receiving waters. The authors quantified the abiotic effects of effluent exposure to sunlight, increased salinity, and a combination of the two factors. Effluent dissolved organic nitrogen showed significant breakdown during the disinfection process (UV and chlorine) and when exposed to sunlight and increasing salinity. Approximately 7% of the EDON was transformed to DIN and dissolved primary amines after exposure to 9 hours of sunlight and a salinity increase from 0 to 33. The production of DIN and primary amines should be taken into account when considering sources of labile nitrogen to aquatic ecosystems. PMID:25842537

  20. Small RNAs in Plant Responses to Abiotic Stresses: Regulatory Roles and Study Methods

    PubMed Central

    Ku, Yee-Shan; Wong, Johanna Wing-Hang; Mui, Zeta; Liu, Xuan; Hui, Jerome Ho-Lam; Chan, Ting-Fung; Lam, Hon-Ming

    2015-01-01

    To survive under abiotic stresses in the environment, plants trigger a reprogramming of gene expression, by transcriptional regulation or translational regulation, to turn on protective mechanisms. The current focus of research on how plants cope with abiotic stresses has transitioned from transcriptomic analyses to small RNA investigations. In this review, we have summarized and evaluated the current methodologies used in the identification and validation of small RNAs and their targets, in the context of plant responses to abiotic stresses. PMID:26501263

  1. WRKY transcription factors

    PubMed Central

    Bakshi, Madhunita; Oelmüller, Ralf

    2014-01-01

    WRKY transcription factors are one of the largest families of transcriptional regulators found exclusively in plants. They have diverse biological functions in plant disease resistance, abiotic stress responses, nutrient deprivation, senescence, seed and trichome development, embryogenesis, as well as additional developmental and hormone-controlled processes. WRKYs can act as transcriptional activators or repressors, in various homo- and heterodimer combinations. Here we review recent progress on the function of WRKY transcription factors in Arabidopsis and other plant species such as rice, potato, and parsley, with a special focus on abiotic, developmental, and hormone-regulated processes. PMID:24492469

  2. Relationship between calcium decoding elements and plant abiotic-stress resistance

    PubMed Central

    Song, Wei-Yi; Zhang, Zheng-Bin; Shao, Hong-Bo; Guo, Xiu-Lin; Cao, Hong-Xing; Zhao, Hong-Bin; Fu, Zheng-Yan; Hu, Xiao-Jun

    2008-01-01

    Serving as an important second messenger, calcium ion has unique properties and universal ability to transmit diverse signals that trigger primary physiological actions in cells in response to hormones, pathogens, light, gravity, and stress factors. Being a second messenger of paramount significance, calcium is required at almost all stages of plant growth and development, playing a fundamental role in regulating polar growth of cells and tissues and participating in plant adaptation to various stress factors. Many researches showed that calcium signals decoding elements are involved in ABA-induced stomatal closure and plant adaptation to drought, cold, salt and other abiotic stresses. Calcium channel proteins like AtTPC1 and TaTPC1 can regulate stomatal closure. Recently some new studies show that Ca2+ is dissolved in water in the apoplast and transported primarily from root to shoot through the transpiration stream. The oscillating amplitudes of [Ca2+]o and [Ca2+]i are controlled by soil Ca2+ concentrations and transpiration rates. Because leaf water use efficiency (WUE) is determined by stomatal closure and transpiration rate, so there may be a close relationship between Ca2+ transporters and stomatal closure as well as WUE, which needs to be studied. The selection of varieties with better drought resistance and high WUE plays an increasing role in bio-watersaving in arid and semi-arid areas on the globe. The current paper reviews the relationship between calcium signals decoding elements and plant drought resistance as well as other abiotic stresses for further study. PMID:18463716

  3. Effects of abiotic stressors on lutein production in the green microalga Dunaliella salina

    PubMed Central

    2014-01-01

    Background Recent years have witnessed a rising trend in exploring microalgae for valuable carotenoid products as the demand for lutein and many other carotenoids in global markets has increased significantly. In green microalgae lutein is a major carotenoid protecting cellular components from damage incurred by reactive oxygen species under stress conditions. In this study, we investigated the effects of abiotic stressors on lutein accumulation in a strain of the marine microalga D. salina which had been selected for growth under stress conditions of combined blue and red lights by adaptive laboratory evolution. Results Nitrate concentration, salinity and light quality were selected as three representative influencing factors and their impact on lutein production in batch cultures of D. salina was evaluated using response surface analysis. D. salina was found to be more tolerant to hyper-osmotic stress than to hypo-osmotic stress which caused serious cell damage and death in a high proportion of cells while hyper-osmotic stress increased the average cell size of D. salina only slightly. Two models were developed to explain how lutein productivity depends on the stress factors and for predicting the optimal conditions for lutein productivity. Among the three stress variables for lutein production, stronger interactions were found between nitrate concentration and salinity than between light quality and the other two. The predicted optimal conditions for lutein production were close to the original conditions used for adaptive evolution of D. salina. This suggests that the conditions imposed during adaptive evolution may have selected for the growth optima arrived at. Conclus