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Sample records for rubisco activities properties

  1. The differential response of photosynthesis to high temperature for a boreal and temperate Populus species relates to differences in Rubisco activation and Rubisco activase properties.

    PubMed

    Hozain, Moh'd I; Salvucci, Michael E; Fokar, Mohamed; Holaday, A Scott

    2010-01-01

    Significant inhibition of photosynthesis occurs at temperatures only a few degrees (activation state of Rubisco and correlated with a higher ATPase activity of Rubisco activase. The temperature response of minimal chlorophyll a fluorescence for darkened leaves was similar for both species and was not consistent with a thylakoid lipid phase change contributing to the decline in A in the range of 30-40 degrees C. Taken together, these data support the idea that the differences in the temperature response of A for the two Populus species could be attributed to the differences in the response of Rubisco activation and ultimately to the thermal properties of Rubisco activase. That the primary sequence of Rubisco activase differed between the species, especially in regions associated with ATPase activity and Rubisco recognition, indicates that the genotypic differences in Rubisco activase might underlie the differences in the heat sensitivity of Rubisco activase and photosynthesis at moderately high temperatures.

  2. The differential response of photosynthesis to high temperature for a boreal and temperate Populus species relates to differences in Rubisco activation and Rubisco activase properties.

    PubMed

    Hozain, Moh'd I; Salvucci, Michael E; Fokar, Mohamed; Holaday, A Scott

    2010-01-01

    Significant inhibition of photosynthesis occurs at temperatures only a few degrees (activation state of Rubisco and correlated with a higher ATPase activity of Rubisco activase. The temperature response of minimal chlorophyll a fluorescence for darkened leaves was similar for both species and was not consistent with a thylakoid lipid phase change contributing to the decline in A in the range of 30-40 degrees C. Taken together, these data support the idea that the differences in the temperature response of A for the two Populus species could be attributed to the differences in the response of Rubisco activation and ultimately to the thermal properties of Rubisco activase. That the primary sequence of Rubisco activase differed between the species, especially in regions associated with ATPase activity and Rubisco recognition, indicates that the genotypic differences in Rubisco activase might underlie the differences in the heat sensitivity of Rubisco activase and photosynthesis at moderately high temperatures. PMID:19864261

  3. Rubisco activity and regulation as targets for crop improvement.

    PubMed

    Parry, Martin A J; Andralojc, P John; Scales, Joanna C; Salvucci, Michael E; Carmo-Silva, A Elizabete; Alonso, Hernan; Whitney, Spencer M

    2013-01-01

    Rubisco (ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase) enables net carbon fixation through the carboxylation of RuBP. However, some characteristics of Rubisco make it surprisingly inefficient and compromise photosynthetic productivity. For example, Rubisco catalyses a wasteful reaction with oxygen that leads to the release of previously fixed CO(2) and NH(3) and the consumption of energy during photorespiration. Furthermore, Rubisco is slow and large amounts are needed to support adequate photosynthetic rates. Consequently, Rubisco has been studied intensively as a prime target for manipulations to 'supercharge' photosynthesis and improve both productivity and resource use efficiency. The catalytic properties of Rubiscos from diverse sources vary considerably, suggesting that changes in turnover rate, affinity, or specificity for CO(2) can be introduced to improve Rubisco performance in specific crops and environments. While attempts to manipulate plant Rubisco by nuclear transformation have had limited success, modifying its catalysis by targeted changes to its catalytic large subunit via chloroplast transformation have been much more successful. However, this technique is still in need of development for most major food crops including maize, wheat, and rice. Other bioengineering approaches for improving Rubisco performance include improving the activity of its ancillary protein, Rubisco activase, in addition to modulating the synthesis and degradation of Rubisco's inhibitory sugar phosphate ligands. As the rate-limiting step in carbon assimilation, even modest improvements in the overall performance of Rubisco pose a viable pathway for obtaining significant gains in plant yield, particularly under stressful environmental conditions.

  4. The activity of Rubisco's molecular chaperone, Rubisco activase, in leaf extracts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rubisco frequently undergoes unproductive interactions with its sugar-phosphate substrate that stabilize active sites in an inactive conformation. Restoring catalytic competence to these sites requires the “molecular chiropractic” activity of Rubisco activase (activase). To make the study of activas...

  5. Rubisco Catalytic Properties and Temperature Response in Crops.

    PubMed

    Hermida-Carrera, Carmen; Kapralov, Maxim V; Galmés, Jeroni

    2016-08-01

    Rubisco catalytic traits and their thermal dependence are two major factors limiting the CO2 assimilation potential of plants. In this study, we present the profile of Rubisco kinetics for 20 crop species at three different temperatures. The results largely confirmed the existence of significant variation in the Rubisco kinetics among species. Although some of the species tended to present Rubisco with higher thermal sensitivity (e.g. Oryza sativa) than others (e.g. Lactuca sativa), interspecific differences depended on the kinetic parameter. Comparing the temperature response of the different kinetic parameters, the Rubisco Km for CO2 presented higher energy of activation than the maximum carboxylation rate and the CO2 compensation point in the absence of mitochondrial respiration. The analysis of the Rubisco large subunit sequence revealed the existence of some sites under adaptive evolution in branches with specific kinetic traits. Because Rubisco kinetics and their temperature dependency were species specific, they largely affected the assimilation potential of Rubisco from the different crops, especially under those conditions (i.e. low CO2 availability at the site of carboxylation and high temperature) inducing Rubisco-limited photosynthesis. As an example, at 25°C, Rubisco from Hordeum vulgare and Glycine max presented, respectively, the highest and lowest potential for CO2 assimilation at both high and low chloroplastic CO2 concentrations. In our opinion, this information is relevant to improve photosynthesis models and should be considered in future attempts to design more efficient Rubiscos. PMID:27329223

  6. Activation of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) by rubisco activase : effects of some sugar phosphates.

    PubMed

    Lilley, R M; Portis, A R

    1990-09-01

    The activation of purified ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) has been studied in the presence of sugar phosphates, and the effect of rubisco activase on this process determined. During an 11-minute time course at pH 7.7 and 11 micromolar CO(2), the activation of rubisco was strongly inhibited by ribulose-1,5-bisphosphate (4 millimolar), fructose-1,6-bisphosphate (1 millimolar) and ribose 5-phosphate (5 millimolar), but this inhibition was overcome by the addition of rubisco activase and activation then proceeded to a greater extent than spontaneous activation of rubisco. Glycerate 3-phosphate (20 millomolar) slowed the initial rate but not the extent of activation and rubisco activase had no effect on this. The activation of rubisco was shown to be affected by phosphoenolpyruvate (3 millimolar) but not by creatine phosphate (3 millimolar) or ATP (3 millimolar), and the creatine-phosphate/creatine phosphokinase system was used to generate the high ATP/ADP quotients required for rubisco activase to function. ATP was shown to be required for the rubisco activase-dependent rubisco activation in the presence of fructose-1,6-bisphosphate (1 millimolar). It is concluded that rubisco activase has a mixed specificity for some sugar phosphate-bound forms of rubisco, but has low or no activity with others. Some possible bases for these differences among sugar phosphates are discussed but remain to be established.

  7. Variation in Rubisco content and activity under variable climatic factors.

    PubMed

    Galmés, Jeroni; Aranjuelo, Iker; Medrano, Hipólito; Flexas, Jaume

    2013-11-01

    The main objective of the present review is to provide a compilation of published data of the effects of several climatic conditions on Rubisco, particularly its activity, state of activation, and concentration, and its influence on leaf gas exchange and photosynthesis. The environmental conditions analyzed include drought, salinity, heavy metals, growth temperature, and elevated [O3], [CO2], and ultraviolet-B irradiance. The results show conclusive evidence for a major negative effect on activity of Rubisco with increasing intensity of a range of abiotic stress factors. This decrease in the activity of Rubisco is associated with down-regulation of the activation state of the enzyme (e.g., by de-carbamylation and/or binding of inhibitory sugar phosphates) in response to drought or high temperature. On the contrary, the negative effects of low temperature, heavy metal stress (cadmium), ozone, and UV-B stress on Rubisco activity are associated with changes in the concentration of Rubisco. Notably, in response to all environmental factors, the regulation of in vivo CO2 assimilation rate was related to Rubisco in vitro parameters, either concentration and/or carboxylation, depending on the particular stress. The importance of the loss of Rubisco activity and its repercussion on plant photosynthesis are discussed in the context of climate change. It is suggested that decreased Rubisco activity will be a major effect induced by climate change, which will need to be considered in any prediction model on plant productivity in the near future.

  8. Enhanced expression of Rubisco activase splicing variants differentially affects Rubisco activity during low temperature treatment in Lolium perenne.

    PubMed

    Jurczyk, Barbara; Pociecha, Ewa; Grzesiak, Maciej; Kalita, Katarzyna; Rapacz, Marcin

    2016-07-01

    Alternative splicing of the Rubisco activase gene was shown to be a point for optimization of photosynthetic carbon assimilation. It can be expected to be a stress-regulated event that depends on plant freezing tolerance. The aim of the study was to examine the relationships among Rubisco activity, the expression of two Rubisco activase splicing variants and photoacclimation to low temperature. The experiment was performed on two Lolium perenne genotypes with contrasting levels of freezing tolerance. The study investigated the effect of pre-hardening (15°C) and cold acclimation (4°C) on net photosynthesis, photosystem II photochemical activity, Rubisco activity and the expression of two splicing variants of the Rubisco activase gene. The results showed an induction of Rubisco activity at both 15°C and 4°C only in a highly freezing-tolerant genotype. The enhanced Rubisco activity after pre-hardening corresponded to increased expression of the splicing variant representing the large isoform, while the increase in Rubisco activity during cold acclimation was due to the activation of both transcript variants. These boosts in Rubisco activity also corresponded to an activation of non-photochemical mechanism of photoacclimation induced at low temperature exclusively in the highly freezing-tolerant genotype. In conclusion, enhanced expression of Rubisco activase splicing variants caused an increase in Rubisco activity during pre-hardening and cold acclimation in the more freezing-tolerant Lolium perenne genotype. The induction of the transcript variant representing the large isoform may be an important element of increasing the carbon assimilation rate supporting the photochemical mechanism of photosynthetic acclimation to cold. PMID:27152456

  9. Can the cold tolerance of C4 photosynthesis in MiscanthusXgiganteus relative to Zea mays be explained by differences in activities and thermal properties of Rubisco?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The chilling-tolerant and biofuel feedstock Miscanthus x giganteus (M. x giganteus) is exceptionally productive among C4 grasses in cold climates. It is able to develop photosynthetically active leaves at temperatures 6°C below the minimum for maize. Rubisco exerts metabolic control over the light-s...

  10. The plastid casein kinase 2 phosphorylates Rubisco activase at the Thr-78 site but is not essential for regulation of Rubisco activation state

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rubisco activase (RCA) is essential for the activation of Rubisco, the carboxylating enzyme of photosynthesis. In Arabidopsis, RCA is encoded by a single gene (At2g39730) that is alternatively spliced to form a large alpha-RCA and small beta-RCA isoform. The activity of Rubisco is controlled in res...

  11. A function-based screen for seeking RubisCO active clones from metagenomes: novel enzymes influencing RubisCO activity.

    PubMed

    Böhnke, Stefanie; Perner, Mirjam

    2015-03-01

    Ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) is a key enzyme of the Calvin cycle, which is responsible for most of Earth's primary production. Although research on RubisCO genes and enzymes in plants, cyanobacteria and bacteria has been ongoing for years, still little is understood about its regulation and activation in bacteria. Even more so, hardly any information exists about the function of metagenomic RubisCOs and the role of the enzymes encoded on the flanking DNA owing to the lack of available function-based screens for seeking active RubisCOs from the environment. Here we present the first solely activity-based approach for identifying RubisCO active fosmid clones from a metagenomic library. We constructed a metagenomic library from hydrothermal vent fluids and screened 1056 fosmid clones. Twelve clones exhibited RubisCO activity and the metagenomic fragments resembled genes from Thiomicrospira crunogena. One of these clones was further analyzed. It contained a 35.2 kb metagenomic insert carrying the RubisCO gene cluster and flanking DNA regions. Knockouts of twelve genes and two intergenic regions on this metagenomic fragment demonstrated that the RubisCO activity was significantly impaired and was attributed to deletions in genes encoding putative transcriptional regulators and those believed to be vital for RubisCO activation. Our new technique revealed a novel link between a poorly characterized gene and RubisCO activity. This screen opens the door to directly investigating RubisCO genes and respective enzymes from environmental samples.

  12. Rubisco activity and regulation as targets for crop improvement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rubisco (ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase) enables net carbon fixation through the carboxylation of RuBP. However, some characteristics of Rubisco make it surprisingly inefficient and compromise photosynthetic productivity. For example, Rubisco catalyses a wasteful reaction wit...

  13. Rubisco catalytic properties of wild and domesticated relatives provide scope for improving wheat photosynthesis.

    PubMed

    Prins, Anneke; Orr, Douglas J; Andralojc, P John; Reynolds, Matthew P; Carmo-Silva, Elizabete; Parry, Martin A J

    2016-03-01

    Rubisco is a major target for improving crop photosynthesis and yield, yet natural diversity in catalytic properties of this enzyme is poorly understood. Rubisco from 25 genotypes of the Triticeae tribe, including wild relatives of bread wheat (Triticum aestivum), were surveyed to identify superior enzymes for improving photosynthesis in this crop. In vitro Rubisco carboxylation velocity (V c), Michaelis-Menten constants for CO2 (K c) and O2 (K o) and specificity factor (S c/o) were measured at 25 and 35 °C. V c and K c correlated positively, while V c and S c/o were inversely related. Rubisco large subunit genes (rbcL) were sequenced, and predicted corresponding amino acid differences analysed in relation to the corresponding catalytic properties. The effect of replacing native wheat Rubisco with counterparts from closely related species was analysed by modelling the response of photosynthesis to varying CO2 concentrations. The model predicted that two Rubisco enzymes would increase photosynthetic performance at 25 °C while only one of these also increased photosynthesis at 35 °C. Thus, under otherwise identical conditions, catalytic variation in the Rubiscos analysed is predicted to improve photosynthetic rates at physiological CO2 concentrations. Naturally occurring Rubiscos with superior properties amongst the Triticeae tribe can be exploited to improve wheat photosynthesis and crop productivity. PMID:26798025

  14. Rubisco catalytic properties of wild and domesticated relatives provide scope for improving wheat photosynthesis.

    PubMed

    Prins, Anneke; Orr, Douglas J; Andralojc, P John; Reynolds, Matthew P; Carmo-Silva, Elizabete; Parry, Martin A J

    2016-03-01

    Rubisco is a major target for improving crop photosynthesis and yield, yet natural diversity in catalytic properties of this enzyme is poorly understood. Rubisco from 25 genotypes of the Triticeae tribe, including wild relatives of bread wheat (Triticum aestivum), were surveyed to identify superior enzymes for improving photosynthesis in this crop. In vitro Rubisco carboxylation velocity (V c), Michaelis-Menten constants for CO2 (K c) and O2 (K o) and specificity factor (S c/o) were measured at 25 and 35 °C. V c and K c correlated positively, while V c and S c/o were inversely related. Rubisco large subunit genes (rbcL) were sequenced, and predicted corresponding amino acid differences analysed in relation to the corresponding catalytic properties. The effect of replacing native wheat Rubisco with counterparts from closely related species was analysed by modelling the response of photosynthesis to varying CO2 concentrations. The model predicted that two Rubisco enzymes would increase photosynthetic performance at 25 °C while only one of these also increased photosynthesis at 35 °C. Thus, under otherwise identical conditions, catalytic variation in the Rubiscos analysed is predicted to improve photosynthetic rates at physiological CO2 concentrations. Naturally occurring Rubiscos with superior properties amongst the Triticeae tribe can be exploited to improve wheat photosynthesis and crop productivity.

  15. Rubisco catalytic properties of wild and domesticated relatives provide scope for improving wheat photosynthesis

    PubMed Central

    Prins, Anneke; Orr, Douglas J.; Andralojc, P. John; Reynolds, Matthew P.; Carmo-Silva, Elizabete; Parry, Martin A. J.

    2016-01-01

    Rubisco is a major target for improving crop photosynthesis and yield, yet natural diversity in catalytic properties of this enzyme is poorly understood. Rubisco from 25 genotypes of the Triticeae tribe, including wild relatives of bread wheat (Triticum aestivum), were surveyed to identify superior enzymes for improving photosynthesis in this crop. In vitro Rubisco carboxylation velocity (V c), Michaelis–Menten constants for CO2 (K c) and O2 (K o) and specificity factor (S c/o) were measured at 25 and 35 °C. V c and K c correlated positively, while V c and S c/o were inversely related. Rubisco large subunit genes (rbcL) were sequenced, and predicted corresponding amino acid differences analysed in relation to the corresponding catalytic properties. The effect of replacing native wheat Rubisco with counterparts from closely related species was analysed by modelling the response of photosynthesis to varying CO2 concentrations. The model predicted that two Rubisco enzymes would increase photosynthetic performance at 25 °C while only one of these also increased photosynthesis at 35 °C. Thus, under otherwise identical conditions, catalytic variation in the Rubiscos analysed is predicted to improve photosynthetic rates at physiological CO2 concentrations. Naturally occurring Rubiscos with superior properties amongst the Triticeae tribe can be exploited to improve wheat photosynthesis and crop productivity. PMID:26798025

  16. The regulatory properties of rubisco activase differ among species and affect photosynthetic induction during light transitions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rubisco’s catalytic chaperone, Rubisco activase (Rca), uses the energy from ATP hydrolysis to restore catalytic competence to Rubisco. In Arabidopsis, inhibition of Rca activity by ADP is fine-tuned by redox regulation of the a-isoform. To elucidate the mechanism for Rca regulation in species contai...

  17. Structural mechanism of RuBisCO activation by carbamylation of the active site lysine

    PubMed Central

    Stec, Boguslaw

    2012-01-01

    Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is a crucial enzyme in carbon fixation and the most abundant protein on earth. It has been studied extensively by biochemical and structural methods; however, the most essential activation step has not yet been described. Here, we describe the mechanistic details of Lys carbamylation that leads to RuBisCO activation by atmospheric CO2. We report two crystal structures of nitrosylated RuBisCO from the red algae Galdieria sulphuraria with O2 and CO2 bound at the active site. G. sulphuraria RuBisCO is inhibited by cysteine nitrosylation that results in trapping of these gaseous ligands. The structure with CO2 defines an elusive, preactivation complex that contains a metal cation Mg2+ surrounded by three H2O/OH molecules. Both structures suggest the mechanism for discriminating gaseous ligands by their quadrupole electric moments. We describe conformational changes that allow for intermittent binding of the metal ion required for activation. On the basis of these structures we propose the individual steps of the activation mechanism. Knowledge of all these elements is indispensable for engineering RuBisCO into a more efficient enzyme for crop enhancement or as a remedy to global warming. PMID:23112176

  18. A tomato chloroplast-targeted DnaJ protein protects Rubisco activity under heat stress.

    PubMed

    Wang, Guodong; Kong, Fanying; Zhang, Song; Meng, Xia; Wang, Yong; Meng, Qingwei

    2015-06-01

    Photosynthesis is one of the biological processes most sensitive to heat stress in plants. Carbon assimilation, which depends on ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), is one of the major sites sensitive to heat stress in photosynthesis. In this study, the roles of a tomato (Solanum lycopersicum) chloroplast-targeted DnaJ protein (SlCDJ2) in resisting heat using sense and antisense transgenic tomatoes were examined. SlCDJ2 was found to be uniformly distributed in the thylakoids and stroma of the chloroplasts. Under heat stress, sense plants exhibited higher chlorophyll contents and fresh weights, and lower accumulation of reactive oxygen species (ROS) and membrane damage. Moreover, Rubisco activity, Rubisco large subunit (RbcL) content, and CO2 assimilation capacity were all higher in sense plants and lower in antisense plants compared with wild-type plants. Thus, SlCDJ2 contributes to maintenance of CO2 assimilation capacity mainly by protecting Rubisco activity under heat stress. SlCDJ2 probably achieves this by keeping the levels of proteolytic enzymes low, which prevents accelerated degradation of Rubisco under heat stress. Furthermore, a chloroplast heat-shock protein 70 was identified as a binding partner of SlCDJ2 in yeast two-hybrid assays. Taken together, these findings establish a role for SlCDJ2 in maintaining Rubisco activity in plants under heat stress. PMID:25801077

  19. A tomato chloroplast-targeted DnaJ protein protects Rubisco activity under heat stress.

    PubMed

    Wang, Guodong; Kong, Fanying; Zhang, Song; Meng, Xia; Wang, Yong; Meng, Qingwei

    2015-06-01

    Photosynthesis is one of the biological processes most sensitive to heat stress in plants. Carbon assimilation, which depends on ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), is one of the major sites sensitive to heat stress in photosynthesis. In this study, the roles of a tomato (Solanum lycopersicum) chloroplast-targeted DnaJ protein (SlCDJ2) in resisting heat using sense and antisense transgenic tomatoes were examined. SlCDJ2 was found to be uniformly distributed in the thylakoids and stroma of the chloroplasts. Under heat stress, sense plants exhibited higher chlorophyll contents and fresh weights, and lower accumulation of reactive oxygen species (ROS) and membrane damage. Moreover, Rubisco activity, Rubisco large subunit (RbcL) content, and CO2 assimilation capacity were all higher in sense plants and lower in antisense plants compared with wild-type plants. Thus, SlCDJ2 contributes to maintenance of CO2 assimilation capacity mainly by protecting Rubisco activity under heat stress. SlCDJ2 probably achieves this by keeping the levels of proteolytic enzymes low, which prevents accelerated degradation of Rubisco under heat stress. Furthermore, a chloroplast heat-shock protein 70 was identified as a binding partner of SlCDJ2 in yeast two-hybrid assays. Taken together, these findings establish a role for SlCDJ2 in maintaining Rubisco activity in plants under heat stress.

  20. Decline of rubisco activity and net photosynthesis in ozone-treated potato foliage. [Solanum tuberosum

    SciTech Connect

    Dann, M.S.; Pell, E.J.

    1987-04-01

    The effect of O/sub 3/ on rubisco activity in Solanum tuberosum L. cv Norland foliage was studied as related to oxidant-induced premature senescence. Plants, 25 days old, were exposed to O/sub 3/ increasing from 0.06 to 0.08 ..mu..1/L for 6 h/day for 4 days in a controlled environment chamber. On day 5 plants were exposed to a 6 h simulated inversion in which O/sub 3/ peaked at 0.12 /sup +/1/L. The authors measured initial and total rubisco activities and net photosynthesis of leaves at full expansion on days 0,3,5,6,9 and 12. These parameters declined in both ozone and control plants throughout the course of the experiment. O/sub 3/ exacerbated the decline and produced a significantly greater decrease following the inversion. The enhanced reduction in rubisco activity over time may be an important characteristics of ozone-induced premature senescence. Rubisco activation (initial/total activity) did not change with the treatment. The decrease in activity is most likely due to a decrease in available protein rather than a decrease in the percentage of rubisco activated in vivo.

  1. Effects of CO/sub 2/ concentration on rubisco amount, activity, and photosynthesis in soybean leaves

    SciTech Connect

    Campbell, W.J.; Allen, L.H. Jr.; Bowes, G.

    1987-04-01

    Soybeans were grown at CO/sub 2/ concentrations ranging from 160 to 990 ..mu..l L/sup -1/ in outdoor chambers receiving natural sunlight. Leaf soluble protein and total rubisco activity decreased with increasing growth CO/sub 2/, when expressed on a dry weight basis, but no decrease occurred on an area basis. On an area basis, leaf photosynthetic rates of plants grown at 330 and 660 ..mu..l CO/sub 2/ L/sup -1/, and measured over a range of intercellular CO/sub 2/ of 50 to 680 ..mu..l CO/sub 2/ L/sup -1/, were always greater in the high CO/sub 2/ grown plants. Rubisco content (percent of soluble protein) and total activity (soluble protein basis), remained unchanged over the range of growth CO/sub 2/. Since rubisco content and total activity per m/sup 2/ were independent of growth CO/sub 2/ concentration, the enhanced rate of photosynthesis of leaves grown at high CO/sub 2/ was apparently not due to an increase in rubisco amount or activity. Soybean grown at high CO/sub 2/ has an extra palisade cell layer per unit leaf area. Thus, the greater photosynthetic rates of high CO/sub 2/ grown leaves may result from an enhanced ability of CO/sub 2/ to gain access to rubisco via increased total mesophyll cell surface area.

  2. The regulatory properties of Rubisco activase differ among species and affect photosynthetic induction during light transitions.

    PubMed

    Carmo-Silva, A Elizabete; Salvucci, Michael E

    2013-04-01

    Rubisco's catalytic chaperone, Rubisco activase (Rca), uses the energy from ATP hydrolysis to restore catalytic competence to Rubisco. In Arabidopsis (Arabidopsis thaliana), inhibition of Rca activity by ADP is fine tuned by redox regulation of the α-isoform. To elucidate the mechanism for Rca regulation in species containing only the redox-insensitive β-isoform, the response of activity to ADP was characterized for different Rca forms. When assayed in leaf extracts, Rubisco activation was significantly inhibited by physiological ratios of ADP to ATP in species containing both α-Rca and β-Rca (Arabidopsis and camelina [Camelina sativa]) or just the β-Rca (tobacco [Nicotiana tabacum]). However, Rca activity was insensitive to ADP inhibition in an Arabidopsis transformant, rwt43, which expresses only Arabidopsis β-Rca, although not in a transformant of Arabidopsis that expresses a tobacco-like β-Rca. ATP hydrolysis by recombinant Arabidopsis β-Rca was much less sensitive to inhibition by ADP than recombinant tobacco β-Rca. Mutation of 17 amino acids in the tobacco β-Rca to the corresponding Arabidopsis residues reduced ADP sensitivity. In planta, Rubisco deactivated at low irradiance except in the Arabidopsis rwt43 transformant containing an ADP-insensitive Rca. Induction of CO2 assimilation after transition from low to high irradiance was much more rapid in the rwt43 transformant compared with plants containing ADP-sensitive Rca forms. The faster rate of photosynthetic induction and a greater enhancement of growth under a fluctuating light regime by the rwt43 transformant compared with wild-type Arabidopsis suggests that manipulation of Rca regulation might provide a strategy for enhancing photosynthetic performance in certain variable light environments.

  3. Rubisco Activity in Guard Cells Compared with the Solute Requirement for Stomatal Opening 1

    PubMed Central

    Reckmann, Udo; Scheibe, Renate; Raschke, Klaus

    1990-01-01

    We investigated whether the reductive pentose phosphate path in guard cells of Pisum sativum had the capacity to contribute significantly to the production of osmotica during stomatal opening in the light. Amounts of ribulose 1,5-bisphophate carboxylase/oxygenase (Rubisco) were determined by the [14C]carboxyarabinitol bisphosphate assay. A guard cell contained about 1.2 and a mesophyll cell about 324 picograms of the enzyme; the ratio was 1:270. The specific activities of Rubisco in guard cells and in mesophyll cells were equal; there was no indication of a specific inhibitor of Rubisco in guard cells. Rubisco activity was 115 femtomol per guard-cell protoplast and hour. This value was different from zero with a probability of 0.99. After exposure of guard-cell protoplasts to 14CO2 for 2 seconds in the light, about one-half of the radioactivity was in phosphorylated compounds and <10% in malate. Guard cells in epidermal strips produced a different labelling pattern; in the light, <10% of the label was in phosphorylated compounds and about 60% in malate. The rate of solute accumulation in intact guard cells was estimated to have been 900 femto-osmol per cell and hour. If Rubisco operated at full capacity in guard cells, and hexoses were produced as osmotica, solutes could be supplied at a rate of 19 femto-osmol per cell and hour, which would constitute 2% of the estimated requirement. The capacity of guard-cell Rubisco to meet the solute requirement for stomatal opening in leaves of Pisum sativum is insignificant. Images Figure 1 PMID:16667255

  4. Rubisco activity in guard cells compared with the solute requirement for stomatal opening. [Pisum sativum

    SciTech Connect

    Reckmann, U.; Scheibe, R.; Raschke, K. )

    1990-01-01

    We investigated whether the reductive pentose phosphate path in guard cells of Pisum sativum had the capacity to contribute significantly to the production of osmotica during stomatal opening in the light. Amounts of ribulose 1,5-bisphophate carboxylase/oxygenase (Rubisco) were determined by the ({sup 14}C) carboxyarabinitol bisphosphate assay. A guard cell contained about 1.2 and a mesophyll cell about 324 picograms of the enzyme; the ratio was 1:270. The specific activities of Rubisco in guard cells and in mesophyll cells were equal; there was no indication of a specific inhibitor of Rubisco in guard cells. Rubisco activity was 115 femtomol per guard-cell protoplast and hour. This value was different from zero with a probability of 0.99. After exposure of guard-cell protoplasts to {sup 14}CO{sub 2} for 2 seconds in the light, about one-half of the radioactivity was in phosphorylated compounds and <10% in malate. Guard cells in epidermal strips produced a different labelling pattern; in the light, <10% of the label was in phosphorylated compounds and about 60% in malate. The rate of solute accumulation in intact guard cells was estimated to have been 900 femto-osmol per cell and hour. If Rubisco operated at full capacity in guard cells, and hexoses were produced as osmotica, solutes could be supplied at a rate of 19femto-osmol per cell and hour, which would constitute 2% of the estimated requirement. The capacity of guard-cell Rubisco to meet the solute requirement for stomatal opening in leaves of Pisum sativum is insignificant.

  5. The Plastid Casein Kinase 2 Phosphorylates Rubisco Activase at the Thr-78 Site but Is Not Essential for Regulation of Rubisco Activation State

    PubMed Central

    Kim, Sang Y.; Bender, Kyle W.; Walker, Berkley J.; Zielinski, Raymond E.; Spalding, Martin H.; Ort, Donald R.; Huber, Steven C.

    2016-01-01

    Rubisco activase (RCA) is essential for the activation of Rubisco, the carboxylating enzyme of photosynthesis. In Arabidopsis, RCA is composed of a large RCAα and small RCAβ isoform that are formed by alternative splicing of a single gene (At2g39730). The activity of Rubisco is controlled in response to changes in irradiance by regulation of RCA activity, which is known to involve a redox-sensitive disulfide bond located in the carboxy-terminal extension of the RCAα subunit. Additionally, phosphorylation of RCA threonine-78 (Thr-78) has been reported to occur in the dark suggesting that phosphorylation may also be associated with dark-inactivation of RCA and deactivation of Rubisco. In the present study, we developed site-specific antibodies to monitor phosphorylation of RCA at the Thr-78 site and used non-reducing SDS-PAGE to monitor the redox status of the RCAα subunit. By immunoblotting, phosphorylation of both RCA isoforms occurred at low light and in the dark and feeding peroxide or DTT to leaf segments indicated that redox status of the chloroplast stroma was a critical factor controlling RCA phosphorylation. Use of a knockout mutant identified the plastid-targeted casein kinase 2 (cpCK2α) as the major protein kinase involved in RCA phosphorylation. Studies with recombinant cpCK2α and synthetic peptide substrates identified acidic residues at the –1, +2, and +3 positions surrounding Thr-78 as strong positive recognition elements. The cpck2 knockout mutant had strongly reduced phosphorylation at the Thr-78 site but was similar to wild type plants in terms of induction kinetics of photosynthesis following transfer from darkness or low light to high light, suggesting that if phosphorylation of RCA Thr-78 plays a direct role it would be redundant to redox regulation for control of Rubisco activation state under normal conditions. PMID:27064346

  6. The catalytic properties of hybrid Rubisco comprising tobacco small and sunflower large subunits mirror the kinetically equivalent source Rubiscos and can support tobacco growth.

    PubMed

    Sharwood, Robert Edward; von Caemmerer, Susanne; Maliga, Pal; Whitney, Spencer Michael

    2008-01-01

    Plastomic replacement of the tobacco (Nicotiana tabacum) Rubisco large subunit gene (rbcL) with that from sunflower (Helianthus annuus; rbcL(S)) produced tobacco(Rst) transformants that produced a hybrid Rubisco consisting of sunflower large and tobacco small subunits (L(s)S(t)). The tobacco(Rst) plants required CO(2) (0.5% v/v) supplementation to grow autotrophically from seed despite the substrate saturated carboxylation rate, K(m), for CO(2) and CO(2)/O(2) selectivity of the L(s)S(t) enzyme mirroring the kinetically equivalent tobacco and sunflower Rubiscos. Consequently, at the onset of exponential growth when the source strength and leaf L(s)S(t) content were sufficient, tobacco(Rst) plants grew to maturity without CO(2) supplementation. When grown under a high pCO(2), the tobacco(Rst) seedlings grew slower than tobacco and exhibited unique growth phenotypes: Juvenile plants formed clusters of 10 to 20 structurally simple oblanceolate leaves, developed multiple apical meristems, and the mature leaves displayed marginal curling and dimpling. Depending on developmental stage, the L(s)S(t) content in tobacco(Rst) leaves was 4- to 7-fold less than tobacco, and gas exchange coupled with chlorophyll fluorescence showed that at 2 mbar pCO(2) and growth illumination CO(2) assimilation in mature tobacco(Rst) leaves remained limited by Rubisco activity and its rate (approximately 11 micromol m(-2) s(-1)) was half that of tobacco controls. (35)S-methionine labeling showed the stability of assembled L(s)S(t) was similar to tobacco Rubisco and measurements of light transient CO(2) assimilation rates showed L(s)S(t) was adequately regulated by tobacco Rubisco activase. We conclude limitations to tobacco(Rst) growth primarily stem from reduced rbcL(S) mRNA levels and the translation and/or assembly of sunflower large with the tobacco small subunits that restricted L(s)S(t) synthesis.

  7. Substitutions at the opening of the Rubisco central solvent channel affect holoenzyme stability and CO2/O 2 specificity but not activation by Rubisco activase.

    PubMed

    Esquivel, M Gloria; Genkov, Todor; Nogueira, Ana S; Salvucci, Michael E; Spreitzer, Robert J

    2013-12-01

    Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the initial step of carbon metabolism in photosynthesis. The holoenzyme comprises eight large subunits, arranged as a tetramer of dimers around a central solvent channel that defines a fourfold axis of symmetry, and eight small subunits, arranged as two tetramers at the poles of the axis. The phylogenetically divergent small-subunit loops between β-strands A and B form the entrance to the solvent channel. In the green alga Chlamydomonas reinhardtii, Ile-58 from each of the four small-subunit βA-βB loops defines the minimal diameter of the channel opening. To understand the role of the central solvent channel in Rubisco function, directed mutagenesis and transformation of Chlamydomonas were employed to replace Ile-58 with Ala, Lys, Glu, Trp, or three Trp residues (I58W3) to close the entrance to the channel. The I58E, I58K, and I58W substitutions caused only small decreases in photosynthetic growth at 25 and 35 °C, whereas I58W3 had a substantial effect at both temperatures. The mutant enzymes had decreased carboxylation rates, but the I58W3 enzyme had decreases in both carboxylation and CO2/O2 specificity. The I58E, I58W, and I58W3 enzymes were inactivated at lower temperatures than wild-type Rubisco, and were degraded at slower rates under oxidative stress. However, these mutant enzymes were activated by Rubisco activase at normal rates, indicating that the structural transition required for carboxylation is not affected by altering the solvent channel opening. Structural dynamics alone may not be responsible for these distant effects on the Rubisco active site.

  8. Brassinosteroids promote photosynthesis and growth by enhancing activation of Rubisco and expression of photosynthetic genes in Cucumis sativus.

    PubMed

    Xia, Xiao-Jian; Huang, Li-Feng; Zhou, Yan-Hong; Mao, Wei-Hua; Shi, Kai; Wu, Jian-Xiang; Asami, Tadao; Chen, Zhixiang; Yu, Jing-Quan

    2009-11-01

    Brassinosteroids (BRs) are a new group of plant growth substances that promote plant growth and productivity. We showed in this study that improved growth of cucumber (Cucumis sativus) plants after treatment with 24-epibrassinolide (EBR), an active BR, was associated with increased CO(2) assimilation and quantum yield of PSII (Phi(PSII)). Treatment of brassinazole (Brz), a specific inhibitor for BR biosynthesis, reduced plant growth and at the same time decreased CO(2) assimilation and Phi(PSII). Thus, the growth-promoting activity of BRs can be, at least partly, attributed to enhanced plant photosynthesis. To understand how BRs enhance photosynthesis, we have analyzed the effects of EBR and Brz on a number of photosynthetic parameters and their affecting factors, including the contents and activity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Northern and Western blotting demonstrated that EBR upregulated, while Brz downregulated, the expressions of rbcL, rbcS and other photosynthetic genes. In addition, EBR had a positive effect on the activation of Rubisco based on increased maximum Rubisco carboxylation rates (V (c,max)), total Rubisco activity and, to a greater extent, initial Rubisco activity. The accumulation patterns of Rubisco activase (RCA) based on immunogold-labeling experiments suggested a role of RCA in BR-regulated activation state of Rubisco. Enhanced expression of genes encoding other Calvin cycle genes after EBR treatment may also play a positive role in RuBP regeneration (J (max)), thereby increasing maximum carboxylation rate of Rubisco (V (c,max)). Thus, BRs promote photosynthesis and growth by positively regulating synthesis and activation of a variety of photosynthetic enzymes including Rubisco in cucumber.

  9. Development of an activity-directed selection system enabled significant improvement of the carboxylation efficiency of Rubisco.

    PubMed

    Cai, Zhen; Liu, Guoxia; Zhang, Junli; Li, Yin

    2014-07-01

    Photosynthetic CO(2) fixation is the ultimate source of organic carbon on earth and thus is essential for crop production and carbon sequestration. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyzes the first step of photosynthetic CO(2) fixation. However, the extreme low carboxylation efficiency of Rubisco makes it the most attractive target for improving photosynthetic efficiency. Extensive studies have focused on re-engineering a more efficient enzyme, but the effort has been impeded by the limited understanding of its structure-function relationships and the lack of an efficient selection system towards its activity. To address the unsuccessful molecular engineering of Rubisco, we developed an Escherichia coli-based activity-directed selection system which links the growth of host cell solely to the Rubisco activity therein. A Synechococcus sp. PCC7002 Rubisco mutant with E49V and D82G substitutions in the small subunit was selected from a total of 15,000 mutants by one round of evolution. This mutant showed an 85% increase in specific carboxylation activity and a 45% improvement in catalytic efficiency towards CO(2). The small-subunit E49V mutation was speculated to influence holoenzyme catalysis through interaction with the large-subunit Q225. This interaction is conserved among various Rubisco from higher plants and Chlamydomonas reinhardtii. Knowledge of these might provide clues for engineering Rubisco from higher plants, with the potential of increasing the crop yield.

  10. Changes of mesophyll and the rubisco activity in pea plants grown in clinostat

    NASA Astrophysics Data System (ADS)

    Adamchuk, N. I.

    In earlier research, it was found that microgravity causes alteration of mesophyll cell parameters and dislication at the ultrastructural level (Kordyum et al., 1989, Nedukha et al., 1991, Kordyum, 1997, Adamchuk et al., 2002). Also, destruction of the fine structure of chloroplasts was reported by Abilov et al. (1986), Aliev et al. (1987), Kordyum et al. (1989), and Adamchuk et al. (1999). In addition, Abilov et al. (1986), Aliev et al. (1987), Brown et al. (1993) have discovered the decrease in starch volume. The objective of this work was to compare quantitative ultrastructural parameters of mesophyll cells (including properties of their chloroplasts) and the level of Rubisco activity detected in clinorotated and control plants of pea (Pisum sativum L.). Plants were grown for 12 days in the nutritional medium of Hogland on a clinostat (with 2 rev. min-1 speed of rotation) at a temperature of 23-25°C and illumination 230 μ mol per m-2s-1. The comparison of transversal cross-sections of leaves has revealed a significant increase of mesophyll cell volume and intercellular space under experimental conditions. This expansion of mesophyll cells has correlated with an increase of the number of chloroplasts. Essential ultrastructural changes have affected the total volume of thylakoids. Also, the value of the photosynthetic membranes development in the clinorotated plants was higher 17.11 ± 1.94 μ m3 then in control -- 12.65 ± 1.83 μ m3 due to extension of destacking thylakoids. Increase of the volume density of plastoglobuli in the clinorotated plants on the 1.63-fold suggested the effect of either greater accumulation of lipid or acceleration of chloroplasts senescence. Under influence of clinorotation, the partial volume of starch inclusions significantly decreased in the spongy mesophyll chloroplasts -- 10.46 ± 1.80 % to compare with control -- 31.34 ± 2.37 %. However, the clinorotation of plants resulted in an increase of the Rubisco activity. Intensities

  11. Temperature responses of the Rubisco maximum carboxylase activity across domains of life: phylogenetic signals, trade-offs, and importance for carbon gain.

    PubMed

    Galmés, J; Kapralov, M V; Copolovici, L O; Hermida-Carrera, C; Niinemets, Ü

    2015-02-01

    Temperature response of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalytic properties directly determines the CO2 assimilation capacity of photosynthetic organisms as well as their survival in environments with different thermal conditions. Despite unquestionable importance of Rubisco, the comprehensive analysis summarizing temperature responses of Rubisco traits across lineages of carbon-fixing organisms is lacking. Here, we present a review of the temperature responses of Rubisco carboxylase specific activity (c(cat)(c)) within and across domains of life. In particular, we consider the variability of temperature responses, and their ecological, physiological, and evolutionary controls. We observed over two-fold differences in the energy of activation (ΔH(a)) among different groups of photosynthetic organisms, and found significant differences between C3 plants from cool habitats, C3 plants from warm habitats and C4 plants. According to phylogenetically independent contrast analysis, ΔH(a) was not related to the species optimum growth temperature (T growth), but was positively correlated with Rubisco specificity factor (S(c/o)) across all organisms. However, when only land plants were analyzed, ΔH(a) was positively correlated with both T(growth) and S(c/o), indicating different trends for these traits in plants versus unicellular aquatic organisms, such as algae and bacteria. The optimum temperature (T(opt)) for k(cat)(c) correlated with S(c/o) for land plants and for all organisms pooled, but the effect of T growth on T(opt) was driven by species phylogeny. The overall phylogenetic signal was significant for all analyzed parameters, stressing the importance of considering the evolutionary framework and accounting for shared ancestry when deciphering relationships between Rubisco kinetic parameters. We argue that these findings have important implications for improving global photosynthesis models.

  12. Photosynthesis and regulation of rubisco activity in net phytoplankton from Delaware Bay

    SciTech Connect

    MacIntyre, H.L.; Geider, R.J.; McKay, R.M.

    1996-10-01

    Net phytoplankton (>20 {mu}m) comprised 51 {plus_minus} 9% of the total chlorophyll (Chl) in a Skeletonema costatum-dominated spring bloom in Delaware Bay. The net phytoplankton had low C:N and high protein:carbohydrate ratios, indicating that their growth was nutrient-replete. Their photosynthetic responses were characterized by low specific absorption, low light-limited and light-saturated rates of photosynthesis, and high quantum yields, indicative of acclimation to low irradiance and internal self-shading. High fucoxanthin: Chl ratios also indicated low light acclimation, but high photoprotective xanthophyll: Chl ratios suggested a high capacity for photoprotective energy dissipation. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) could be activated and deactivated in response to changes in irradiance and was fully activated at the surface of the water column and fully deactivated in aphotic deep water. Maximum Rubisco activity was correlated with Rubisco content and bulk protein content of the phytoplankton and with light-saturated rates of photosynthesis measured in short (<20-min) incubations. Long (60-min) incubations caused a decrease in the light-saturated rate of photosynthesis, possibly because of feedback limitation. While feedback limitation is unlikely to occur in the water column it should be considered when estimating productivity in well-mixed waters from fixed light-depth incubations. 90 refs., 7 figs., 2 tabs.

  13. The temperature response of CO2 assimilation, photochemical activities and Rubisco activation in Camelina sativa, a potential bioenergy crop with limited capacity for acclimation to heat stress.

    PubMed

    Carmo-Silva, A Elizabete; Salvucci, Michael E

    2012-11-01

    The temperature optimum of photosynthesis coincides with the average daytime temperature in a species' native environment. Moderate heat stress occurs when temperatures exceed the optimum, inhibiting photosynthesis and decreasing productivity. In the present study, the temperature response of photosynthesis and the potential for heat acclimation was evaluated for Camelina sativa, a bioenergy crop. The temperature optimum of net CO(2) assimilation rate (A) under atmospheric conditions was 30-32 °C and was only slightly higher under non-photorespiratory conditions. The activation state of Rubisco was closely correlated with A at supra-optimal temperatures, exhibiting a parallel decrease with increasing leaf temperature. At both control and elevated temperatures, the modeled response of A to intercellular CO(2) concentration was consistent with Rubisco limiting A at ambient CO(2). Rubisco activation and photochemical activities were affected by moderate heat stress at lower temperatures in camelina than in the warm-adapted species cotton and tobacco. Growth under conditions that imposed a daily interval of moderate heat stress caused a 63 % reduction in camelina seed yield. Levels of cpn60 protein were elevated under the higher growth temperature, but acclimation of photosynthesis was minimal. Inactivation of Rubisco in camelina at temperatures above 35 °C was consistent with the temperature response of Rubisco activase activity and indicated that Rubisco activase was a prime target of inhibition by moderate heat stress in camelina. That photosynthesis exhibited no acclimation to moderate heat stress will likely impact the development of camelina and other cool season Brassicaceae as sources of bioenergy in a warmer world.

  14. Regulation of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) activase: product inhibition, cooperativity, and magnesium activation.

    PubMed

    Hazra, Suratna; Henderson, J Nathan; Liles, Kevin; Hilton, Matthew T; Wachter, Rebekka M

    2015-10-01

    In many photosynthetic organisms, tight-binding Rubisco inhibitors are released by the motor protein Rubisco activase (Rca). In higher plants, Rca plays a pivotal role in regulating CO2 fixation. Here, the ATPase activity of 0.005 mm tobacco Rca was monitored under steady-state conditions, and global curve fitting was utilized to extract kinetic constants. The kcat was best fit by 22.3 ± 4.9 min(-1), the Km for ATP by 0.104 ± 0.024 mm, and the Ki for ADP by 0.037 ± 0.007 mm. Without ADP, the Hill coefficient for ATP hydrolysis was extracted to be 1.0 ± 0.1, indicating noncooperative behavior of homo-oligomeric Rca assemblies. However, the addition of ADP was shown to introduce positive cooperativity between two or more subunits (Hill coefficient 1.9 ± 0.2), allowing for regulation via the prevailing ATP/ADP ratio. ADP-mediated activation was not observed, although larger amounts led to competitive product inhibition of hydrolytic activity. The catalytic efficiency increased 8.4-fold upon cooperative binding of a second magnesium ion (Hill coefficient 2.5 ± 0.5), suggesting at least three conformational states (ATP-bound, ADP-bound, and empty) within assemblies containing an average of about six subunits. The addition of excess Rubisco (24:1, L8S8/Rca6) and crowding agents did not modify catalytic rates. However, high magnesium provided for thermal Rca stabilization. We propose that magnesium mediates the formation of closed hexameric toroids capable of high turnover rates and amenable to allosteric regulation. We suggest that in vivo, the Rca hydrolytic activity is tuned by fluctuating [Mg(2+)] in response to changes in available light.

  15. Regulation of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) activase: product inhibition, cooperativity, and magnesium activation.

    PubMed

    Hazra, Suratna; Henderson, J Nathan; Liles, Kevin; Hilton, Matthew T; Wachter, Rebekka M

    2015-10-01

    In many photosynthetic organisms, tight-binding Rubisco inhibitors are released by the motor protein Rubisco activase (Rca). In higher plants, Rca plays a pivotal role in regulating CO2 fixation. Here, the ATPase activity of 0.005 mm tobacco Rca was monitored under steady-state conditions, and global curve fitting was utilized to extract kinetic constants. The kcat was best fit by 22.3 ± 4.9 min(-1), the Km for ATP by 0.104 ± 0.024 mm, and the Ki for ADP by 0.037 ± 0.007 mm. Without ADP, the Hill coefficient for ATP hydrolysis was extracted to be 1.0 ± 0.1, indicating noncooperative behavior of homo-oligomeric Rca assemblies. However, the addition of ADP was shown to introduce positive cooperativity between two or more subunits (Hill coefficient 1.9 ± 0.2), allowing for regulation via the prevailing ATP/ADP ratio. ADP-mediated activation was not observed, although larger amounts led to competitive product inhibition of hydrolytic activity. The catalytic efficiency increased 8.4-fold upon cooperative binding of a second magnesium ion (Hill coefficient 2.5 ± 0.5), suggesting at least three conformational states (ATP-bound, ADP-bound, and empty) within assemblies containing an average of about six subunits. The addition of excess Rubisco (24:1, L8S8/Rca6) and crowding agents did not modify catalytic rates. However, high magnesium provided for thermal Rca stabilization. We propose that magnesium mediates the formation of closed hexameric toroids capable of high turnover rates and amenable to allosteric regulation. We suggest that in vivo, the Rca hydrolytic activity is tuned by fluctuating [Mg(2+)] in response to changes in available light. PMID:26283786

  16. Catalytic roles of flexible regions at the active site of ribulose-bisphosphate carboxylase/oxygenase (Rubisco)

    SciTech Connect

    Hartman, F.C.; Harpel, M.R.; Chen, Yuh-Ru; Larson, E.M.; Larimer, F.W.

    1995-12-31

    Chemical and mutagenesis studies of Rubisco have identified Lys329 and Glu48 as active-site residues that are located in distinct, interacting domains from adjacent subunits. Crystallographic analyses have shown that Lys329 is the apical residue in a 12-residue flexible loop (loop 6) of the {Beta},{alpha}-barrel domain of the active site and that Glu48 resides at the end of helix B of the N-terminal domain of the active site. When phosphorylated ligands are bound by the enzyme, loop 6 adopts a closed conformation and, in concert with repositioning of helix B, thereby occludes the active site from the external environment. In this closed conformation, the {gamma}-carboxylate of Glu48 and the {epsilon}-amino group of Lys329 engage in intersubunit electrostatic interaction. By use of appropriate site-directed mutants of Rhodospirillum rubrum Rubisco, we are addressing several issues: the catalytic roles of Lys329 and Glu48, the functional significance of the intersubunit salt bridge comprised of these two residues, and the roles of loop 6 and helix B in stabilizing labile reaction intermediates. Characterization of novel products derived from misprocessing of D-ribulose-1,5-bisphosphate (RuBP) by the mutant proteins have illuminated the structure of the key intermediate in the normal oxygenase pathway.

  17. Isolation and kinetic characterisation of hydrophobically distinct populations of form I Rubisco

    PubMed Central

    2014-01-01

    Background Rubisco (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is a Calvin Cycle enzyme involved in CO2 assimilation. It is thought to be a major cause of photosynthetic inefficiency, suffering from both a slow catalytic rate and lack of specificity due to a competing reaction with oxygen. Revealing and understanding the engineering rules that dictate Rubisco’s activity could have a significant impact on photosynthetic efficiency and crop yield. Results This paper describes the purification and characterisation of a number of hydrophobically distinct populations of Rubisco from both Spinacia oleracea and Brassica oleracea extracts. The populations were obtained using a novel and rapid purification protocol that employs hydrophobic interaction chromatography (HIC) as a form I Rubisco enrichment procedure, resulting in distinct Rubisco populations of expected enzymatic activities, high purities and integrity. Conclusions We demonstrate here that HIC can be employed to isolate form I Rubisco with purities and activities comparable to those obtained via ion exchange chromatography (IEC). Interestingly, and in contrast to other published purification methods, HIC resulted in the isolation of a number of hydrophobically distinct Rubisco populations. Our findings reveal a so far unaccounted diversity in the hydrophobic properties within form 1 Rubisco. By employing HIC to isolate and characterise Spinacia oleracea and Brassica oleracea, we show that the presence of these distinct Rubisco populations is not species specific, and we report for the first time the kinetic properties of Rubisco from Brassica oleracea extracts. These observations may aid future studies concerning Rubisco’s structural and functional properties. PMID:24987448

  18. Modified rubisco large subunit n-methyltransferase useful for targeting molecules to the active-site vicinity of ribulose-1,5-bisphosphate

    DOEpatents

    Houtz, Robert L.

    2012-03-20

    The present invention generally relates to a modified Rubisco large subunit .sup..epsilon.N-Methyltransferase (Rubisco LSMT, or RLSMT). The present invention also relates to a modified RLSMT-carbonic anhydrase (RLSMT-CA). This modified RLSMT-CA improves the efficiency of the reduction of CO.sub.2 during photosynthesis, which may increase plant growth rates. The present invention also relates to nucleic acids encoding the modified RLSMT-CA or modified RLSMT. Also, the present invention relates to cells including the modified RLSMT-CA or modified RLSMT, plants containing the modified RLSMT-CA or modified RLSMT, and methods using compositions of the present invention. In addition, the present invention relates to antibodies conjugated to CA which may bind to Rubisco, and antibodies which bind a modified RLSMT-CA. The invention also relates to modified forms of the LS and SS of Rubisco where the modified forms are fusions with CA or biologically active fragments thereof. The present invention provides methods of altering Rubisco carboxylase activity and altering plant growth.

  19. Biophysical characterization of higher plant Rubisco activase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rubisco activase (Rca) is a chaperone-like protein of the AAA+ family, which uses mechanochemical energy derived from ATP hydrolysis to release tightly bound inhibitors from the active site of the primary carbon fixing enzyme ribulose 1,5-bisphosphate oxygenase/carboxylase (Rubisco). Mechanistic and...

  20. Rubisco mutagenesis provides new insight into limitations on photosynthesis and growth in Synechocystis PCC6803.

    PubMed

    Marcus, Yehouda; Altman-Gueta, Hagit; Wolff, Yael; Gurevitz, Michael

    2011-08-01

    Orthophosphate (Pi) stimulates the activation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) while paradoxically inhibiting its catalysis. Of three Pi-binding sites, the roles of the 5P- and latch sites have been documented, whereas that of the 1P-site remained unclear. Conserved residues at the 1P-site of Rubisco from the cyanobacterium Synechocystis PCC6803 were substituted and the kinetic properties of the enzyme derivatives and effects on cell photosynthesis and growth were examined. While Pi-stimulated Rubisco activation diminished for enzyme mutants T65A/S and G404A, inhibition of catalysis by Pi remained unchanged. Together with previous studies, the results suggest that all three Pi-binding sites are involved in stimulation of Rubisco activation, whereas only the 5P-site is involved in inhibition of catalysis. While all the mutations reduced the catalytic turnover of Rubisco (K(cat)) between 6- and 20-fold, the photosynthesis and growth rates under saturating irradiance and inorganic carbon (Ci) concentrations were only reduced 40-50% (in the T65A/S mutants) or not at all (G404A mutant). Analysis of the mutant cells revealed a 3-fold increase in Rubisco content that partially compensated for the reduced K(cat) so that the carboxylation rate per chlorophyll was one-third of that in the wild type. Correlation between the kinetic properties of Rubisco and the photosynthetic rate (P(max)) under saturating irradiance and Ci concentrations indicate that a >60% reduction in K(cat) can be tolerated before P(max) in Synechocystsis PCC6803 is affected. These results indicate that the limitation of Rubisco activity on the rate of photosynthesis in Synechocystis is low. Determination of Calvin cycle metabolites revealed that unlike in higher plants, cyanobacterial photosynthesis is constrained by phosphoglycerate reduction probably due to limitation of ATP or NADPH. PMID:21551078

  1. Rubisco mutagenesis provides new insight into limitations on photosynthesis and growth in Synechocystis PCC6803.

    PubMed

    Marcus, Yehouda; Altman-Gueta, Hagit; Wolff, Yael; Gurevitz, Michael

    2011-08-01

    Orthophosphate (Pi) stimulates the activation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) while paradoxically inhibiting its catalysis. Of three Pi-binding sites, the roles of the 5P- and latch sites have been documented, whereas that of the 1P-site remained unclear. Conserved residues at the 1P-site of Rubisco from the cyanobacterium Synechocystis PCC6803 were substituted and the kinetic properties of the enzyme derivatives and effects on cell photosynthesis and growth were examined. While Pi-stimulated Rubisco activation diminished for enzyme mutants T65A/S and G404A, inhibition of catalysis by Pi remained unchanged. Together with previous studies, the results suggest that all three Pi-binding sites are involved in stimulation of Rubisco activation, whereas only the 5P-site is involved in inhibition of catalysis. While all the mutations reduced the catalytic turnover of Rubisco (K(cat)) between 6- and 20-fold, the photosynthesis and growth rates under saturating irradiance and inorganic carbon (Ci) concentrations were only reduced 40-50% (in the T65A/S mutants) or not at all (G404A mutant). Analysis of the mutant cells revealed a 3-fold increase in Rubisco content that partially compensated for the reduced K(cat) so that the carboxylation rate per chlorophyll was one-third of that in the wild type. Correlation between the kinetic properties of Rubisco and the photosynthetic rate (P(max)) under saturating irradiance and Ci concentrations indicate that a >60% reduction in K(cat) can be tolerated before P(max) in Synechocystsis PCC6803 is affected. These results indicate that the limitation of Rubisco activity on the rate of photosynthesis in Synechocystis is low. Determination of Calvin cycle metabolites revealed that unlike in higher plants, cyanobacterial photosynthesis is constrained by phosphoglycerate reduction probably due to limitation of ATP or NADPH.

  2. Effect of CO sub 2 enrichment and high photosynthetic photon flux densities (PPFD) on rubisco and PEP-case activities of in vitro cultured strawberry plants

    SciTech Connect

    Desjardins, Y.; Beeson, R.; Gosselin, A. )

    1989-04-01

    Standard growing conditions in vitro (low light and CO{sub 2}) are not conducive to autotrophy. An experiment was conducted to improve photosynthesis in vitro in the hope of increasing survival in acclimatization. A factorial experiment was elaborated where CO{sub 2} and PPFD were supplied to in vitro cultured strawberry plants in the rooting stage. Activities of carboxylating enzymes were determined after 4 weeks of culture. The activities of non-activated and activated rubisco and PEP-Case were measured after extraction of the enzymes and a reaction with NaH{sup 14}CO{sub 3} followed by scintillation counting spectroscopy. High CO{sub 2} concentration significantly increased net assimilation rates (NAR) by 165% over the control for both 1650 and 3000 ppm CO{sub 2}. High PPFD only increased NAR by 12 and 35% for 150 and 250 {mu}mol{center dot}m{sup {minus}2}{center dot}s{sup {minus}1} respectively over the control. Plants grown at 3000 ppm CO{sub 2} had the highest level of chlorophyll/g FW with 97% more than the control. The activity of PEP-Case was the highest at high light levels and high CO{sub 2} with rates of 1.65 for 1650 ppm versus 1.22 mmol CO{sub 2} mg{sup {minus}1} chl. h{sup {minus}1} at 250 {mu}mol{center dot}m{sup {minus}2}{center dot}s{sup {minus}1}. There was no difference in PEP activity at low light levels. The rubisco activity was lower at 1650 and 3000 ppm CO{sub 2}. Increases in NAR correlate more closely to the PEP-Case than to Rubisco activity. Physiological significance of high activity of PEP-Case over rubisco will be discussed.

  3. Evolving Methanococcoides burtonii archaeal Rubisco for improved photosynthesis and plant growth.

    PubMed

    Wilson, Robert H; Alonso, Hernan; Whitney, Spencer M

    2016-03-01

    In photosynthesis Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyses the often rate limiting CO2-fixation step in the Calvin cycle. This makes Rubisco both the gatekeeper for carbon entry into the biosphere and a target for functional improvement to enhance photosynthesis and plant growth. Encumbering the catalytic performance of Rubisco is its highly conserved, complex catalytic chemistry. Accordingly, traditional efforts to enhance Rubisco catalysis using protracted "trial and error" protein engineering approaches have met with limited success. Here we demonstrate the versatility of high throughput directed (laboratory) protein evolution for improving the carboxylation properties of a non-photosynthetic Rubisco from the archaea Methanococcoides burtonii. Using chloroplast transformation in the model plant Nicotiana tabacum (tobacco) we confirm the improved forms of M. burtonii Rubisco increased photosynthesis and growth relative to tobacco controls producing wild-type M. burtonii Rubisco. Our findings indicate continued directed evolution of archaeal Rubisco offers new potential for enhancing leaf photosynthesis and plant growth.

  4. Atomic resolution x-ray structure of the substrate recognition domain of higher plant rubisco activase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rapid release of tight-binding inhibitors from dead-end Rubisco complexes requires the activity of Rubisco activase, an AAA+ ATPase that utilizes chemo-mechanical energy to catalyze the reactivation of Rubisco. Activase is thought to play a central role in coordinating the rate of CO2 fixation w...

  5. Exogenous sucrose supply changes sugar metabolism and reduces photosynthesis of sugarcane through the down-regulation of Rubisco abundance and activity.

    PubMed

    Lobo, Ana Karla Moreira; de Oliveira Martins, Marcio; Lima Neto, Milton Costa; Machado, Eduardo Caruso; Ribeiro, Rafael Vasconcelos; Silveira, Joaquim Albenisio Gomes

    2015-05-01

    Photosynthetic modulation by sugars has been known for many years, but the biochemical and molecular comprehension of this process is lacking. We studied how the exogenous sucrose supplied to leaves could affect sugar metabolism in leaf, sheath and stalk and inhibit photosynthesis in four-month old sugarcane plants. Exogenous sucrose 50mM sprayed on attached leaves strongly impaired the net CO2 assimilation (PN) and decreased the instantaneous carboxylation efficiency (PN/Ci), suggesting that the impairment in photosynthesis was caused by biochemical restrictions. The photosystem II activity was also affected by excess sucrose as indicated by the reduction in the apparent electron transport rate, effective quantum yield and increase in non-photochemical quenching. In leaf segments, sucrose accumulation was related to increases in the activities of soluble acid and neutral invertases, sucrose synthase and sucrose phosphate synthase, whereas the contents of fructose increased and glucose slightly decreased. Changes in the activities of sucrose hydrolyzing and synthesizing enzymes in leaf, sheath and stalk and sugar profile in intact plants were not enough to identify which sugar(s) or enzyme(s) were directly involved in photosynthesis modulation. However, exogenous sucrose was able to trigger down-regulation in the Rubisco abundance, activation state and enzymatic activity. Despite the fact that PN/Ci had been notably decreased by sucrose, in vitro activity and abundance of PEPCase did not change, suggesting an in vivo modulation of this enzyme. The data reveal that sucrose and/or other derivative sugars in leaves inhibited sugarcane photosynthesis by down-regulation of Rubisco synthesis and activity. Our data also suggest that sugar modulation was not exerted by a feedback mechanism induced by the accumulation of sugars in immature sugarcane stalk. PMID:25863283

  6. Exogenous sucrose supply changes sugar metabolism and reduces photosynthesis of sugarcane through the down-regulation of Rubisco abundance and activity.

    PubMed

    Lobo, Ana Karla Moreira; de Oliveira Martins, Marcio; Lima Neto, Milton Costa; Machado, Eduardo Caruso; Ribeiro, Rafael Vasconcelos; Silveira, Joaquim Albenisio Gomes

    2015-05-01

    Photosynthetic modulation by sugars has been known for many years, but the biochemical and molecular comprehension of this process is lacking. We studied how the exogenous sucrose supplied to leaves could affect sugar metabolism in leaf, sheath and stalk and inhibit photosynthesis in four-month old sugarcane plants. Exogenous sucrose 50mM sprayed on attached leaves strongly impaired the net CO2 assimilation (PN) and decreased the instantaneous carboxylation efficiency (PN/Ci), suggesting that the impairment in photosynthesis was caused by biochemical restrictions. The photosystem II activity was also affected by excess sucrose as indicated by the reduction in the apparent electron transport rate, effective quantum yield and increase in non-photochemical quenching. In leaf segments, sucrose accumulation was related to increases in the activities of soluble acid and neutral invertases, sucrose synthase and sucrose phosphate synthase, whereas the contents of fructose increased and glucose slightly decreased. Changes in the activities of sucrose hydrolyzing and synthesizing enzymes in leaf, sheath and stalk and sugar profile in intact plants were not enough to identify which sugar(s) or enzyme(s) were directly involved in photosynthesis modulation. However, exogenous sucrose was able to trigger down-regulation in the Rubisco abundance, activation state and enzymatic activity. Despite the fact that PN/Ci had been notably decreased by sucrose, in vitro activity and abundance of PEPCase did not change, suggesting an in vivo modulation of this enzyme. The data reveal that sucrose and/or other derivative sugars in leaves inhibited sugarcane photosynthesis by down-regulation of Rubisco synthesis and activity. Our data also suggest that sugar modulation was not exerted by a feedback mechanism induced by the accumulation of sugars in immature sugarcane stalk.

  7. Rubisco mutants of Chlamydomonas reinhardtii enhance photosynthetic hydrogen production.

    PubMed

    Pinto, T S; Malcata, F X; Arrabaça, J D; Silva, J M; Spreitzer, R J; Esquível, M G

    2013-06-01

    Molecular hydrogen (H2) is an ideal fuel characterized by high enthalpy change and lack of greenhouse effects. This biofuel can be released by microalgae via reduction of protons to molecular hydrogen catalyzed by hydrogenases. The main competitor for the reducing power required by the hydrogenases is the Calvin cycle, and rubisco plays a key role therein. Engineered Chlamydomonas with reduced rubisco levels, activity and stability was used as the basis of this research effort aimed at increasing hydrogen production. Biochemical monitoring in such metabolically engineered mutant cells proceeded in Tris/acetate/phosphate culture medium with S-depletion or repletion, both under hypoxia. Photosynthetic activity, maximum photochemical efficiency, chlorophyll and protein levels were all measured. In addition, expression of rubisco, hydrogenase, D1 and Lhcb were investigated, and H2 was quantified. At the beginning of the experiments, rubisco increased followed by intense degradation. Lhcb proteins exhibited monomeric isoforms during the first 24 to 48 h, and D1 displayed sensitivity under S-depletion. Rubisco mutants exhibited a significant decrease in O2 evolution compared with the control. Although the S-depleted medium was much more suitable than its complete counterpart for H2 production, hydrogen release was observed also in sealed S-repleted cultures of rubisco mutated cells under low-moderate light conditions. In particular, the rubisco mutant Y67A accounted for 10-15-fold higher hydrogen production than the wild type under the same conditions and also displayed divergent metabolic parameters. These results indicate that rubisco is a promising target for improving hydrogen production rates in engineered microalgae.

  8. Widespread positive selection in the photosynthetic Rubisco enzyme

    PubMed Central

    Kapralov, Maxim V; Filatov, Dmitry A

    2007-01-01

    Background Rubisco enzyme catalyzes the first step in net photosynthetic CO2 assimilation and photorespiratory carbon oxidation and is responsible for almost all carbon fixation on Earth. The large subunit of Rubisco is encoded by the chloroplast rbcL gene, which is widely used for reconstruction of plant phylogenies due to its conservative nature. Plant systematicists have mainly used rbcL paying little attention to its function, and the question whether it evolves under Darwinian selection has received little attention. The purpose of our study was to evaluate how common is positive selection in Rubisco among the phototrophs and where in the Rubisco structure does positive selection occur. Results We searched for positive selection in rbcL sequences from over 3000 species representing all lineages of green plants and some lineages of other phototrophs, such as brown and red algae, diatoms, euglenids and cyanobacteria. Our molecular phylogenetic analysis found the presence of positive selection in rbcL of most analyzed land plants, but not in algae and cyanobacteria. The mapping of the positively selected residues on the Rubisco tertiary structure revealed that they are located in regions important for dimer-dimer, intradimer, large subunit-small subunit and Rubisco-Rubisco activase interactions, and that some of the positively selected residues are close to the active site. Conclusion Our results demonstrate that despite its conservative nature, Rubisco evolves under positive selection in most lineages of land plants, and after billions of years of evolution Darwinian selection still fine-tunes its performance. Widespread positive selection in rbcL has to be taken into account when this gene is used for phylogenetic reconstructions. PMID:17498284

  9. Large variation in the Rubisco kinetics of diatoms reveals diversity among their carbon-concentrating mechanisms.

    PubMed

    Young, Jodi N; Heureux, Ana M C; Sharwood, Robert E; Rickaby, Rosalind E M; Morel, François M M; Whitney, Spencer M

    2016-05-01

    While marine phytoplankton rival plants in their contribution to global primary productivity, our understanding of their photosynthesis remains rudimentary. In particular, the kinetic diversity of the CO2-fixing enzyme, Rubisco, in phytoplankton remains unknown. Here we quantify the maximum rates of carboxylation (k cat (c)), oxygenation (k cat (o)), Michaelis constants (K m) for CO2 (K C) and O2 (K O), and specificity for CO2 over O2 (SC/O) for Form I Rubisco from 11 diatom species. Diatom Rubisco shows greater variation in K C (23-68 µM), SC/O (57-116mol mol(-1)), and K O (413-2032 µM) relative to plant and algal Rubisco. The broad range of K C values mostly exceed those of C4 plant Rubisco, suggesting that the strength of the carbon-concentrating mechanism (CCM) in diatoms is more diverse, and more effective than previously predicted. The measured k cat (c) for each diatom Rubisco showed less variation (2.1-3.7s(-1)), thus averting the canonical trade-off typically observed between K C and k cat (c) for plant Form I Rubisco. Uniquely, a negative relationship between K C and cellular Rubisco content was found, suggesting variation among diatom species in how they allocate their limited cellular resources between Rubisco synthesis and their CCM. The activation status of Rubisco in each diatom was low, indicating a requirement for Rubisco activase. This work highlights the need to better understand the correlative natural diversity between the Rubisco kinetics and CCM of diatoms and the underpinning mechanistic differences in catalytic chemistry among the Form I Rubisco superfamily. PMID:27129950

  10. Large variation in the Rubisco kinetics of diatoms reveals diversity among their carbon-concentrating mechanisms

    PubMed Central

    Young, Jodi N.; Heureux, Ana M.C.; Sharwood, Robert E.; Rickaby, Rosalind E.M.; Morel, François M.M.; Whitney, Spencer M.

    2016-01-01

    While marine phytoplankton rival plants in their contribution to global primary productivity, our understanding of their photosynthesis remains rudimentary. In particular, the kinetic diversity of the CO2-fixing enzyme, Rubisco, in phytoplankton remains unknown. Here we quantify the maximum rates of carboxylation (k cat c), oxygenation (k cat o), Michaelis constants (K m) for CO2 (K C) and O2 (K O), and specificity for CO2 over O2 (SC/O) for Form I Rubisco from 11 diatom species. Diatom Rubisco shows greater variation in K C (23–68 µM), SC/O (57–116mol mol−1), and K O (413–2032 µM) relative to plant and algal Rubisco. The broad range of K C values mostly exceed those of C4 plant Rubisco, suggesting that the strength of the carbon-concentrating mechanism (CCM) in diatoms is more diverse, and more effective than previously predicted. The measured k cat c for each diatom Rubisco showed less variation (2.1–3.7s−1), thus averting the canonical trade-off typically observed between K C and k cat c for plant Form I Rubisco. Uniquely, a negative relationship between K C and cellular Rubisco content was found, suggesting variation among diatom species in how they allocate their limited cellular resources between Rubisco synthesis and their CCM. The activation status of Rubisco in each diatom was low, indicating a requirement for Rubisco activase. This work highlights the need to better understand the correlative natural diversity between the Rubisco kinetics and CCM of diatoms and the underpinning mechanistic differences in catalytic chemistry among the Form I Rubisco superfamily. PMID:27129950

  11. Large variation in the Rubisco kinetics of diatoms reveals diversity among their carbon-concentrating mechanisms.

    PubMed

    Young, Jodi N; Heureux, Ana M C; Sharwood, Robert E; Rickaby, Rosalind E M; Morel, François M M; Whitney, Spencer M

    2016-05-01

    While marine phytoplankton rival plants in their contribution to global primary productivity, our understanding of their photosynthesis remains rudimentary. In particular, the kinetic diversity of the CO2-fixing enzyme, Rubisco, in phytoplankton remains unknown. Here we quantify the maximum rates of carboxylation (k cat (c)), oxygenation (k cat (o)), Michaelis constants (K m) for CO2 (K C) and O2 (K O), and specificity for CO2 over O2 (SC/O) for Form I Rubisco from 11 diatom species. Diatom Rubisco shows greater variation in K C (23-68 µM), SC/O (57-116mol mol(-1)), and K O (413-2032 µM) relative to plant and algal Rubisco. The broad range of K C values mostly exceed those of C4 plant Rubisco, suggesting that the strength of the carbon-concentrating mechanism (CCM) in diatoms is more diverse, and more effective than previously predicted. The measured k cat (c) for each diatom Rubisco showed less variation (2.1-3.7s(-1)), thus averting the canonical trade-off typically observed between K C and k cat (c) for plant Form I Rubisco. Uniquely, a negative relationship between K C and cellular Rubisco content was found, suggesting variation among diatom species in how they allocate their limited cellular resources between Rubisco synthesis and their CCM. The activation status of Rubisco in each diatom was low, indicating a requirement for Rubisco activase. This work highlights the need to better understand the correlative natural diversity between the Rubisco kinetics and CCM of diatoms and the underpinning mechanistic differences in catalytic chemistry among the Form I Rubisco superfamily.

  12. Biochemical characterization of predicted Precambrian RuBisCO.

    PubMed

    Shih, Patrick M; Occhialini, Alessandro; Cameron, Jeffrey C; Andralojc, P John; Parry, Martin A J; Kerfeld, Cheryl A

    2016-01-01

    The antiquity and global abundance of the enzyme, RuBisCO, attests to the crucial and longstanding role it has played in the biogeochemical cycles of Earth over billions of years. The counterproductive oxygenase activity of RuBisCO has persisted over billions of years of evolution, despite its competition with the carboxylase activity necessary for carbon fixation, yet hypotheses regarding the selective pressures governing RuBisCO evolution have been limited to speculation. Here we report the resurrection and biochemical characterization of ancestral RuBisCOs, dating back to over one billion years ago (Gyr ago). Our findings provide an ancient point of reference revealing divergent evolutionary paths taken by eukaryotic homologues towards improved specificity for CO2, versus the evolutionary emphasis on increased rates of carboxylation observed in bacterial homologues. Consistent with these distinctions, in vivo analysis reveals the propensity of ancestral RuBisCO to be encapsulated into modern-day carboxysomes, bacterial organelles central to the cyanobacterial CO2 concentrating mechanism.

  13. Biochemical characterization of predicted Precambrian RuBisCO

    PubMed Central

    Shih, Patrick M.; Occhialini, Alessandro; Cameron, Jeffrey C.; Andralojc, P John; Parry, Martin A. J.; Kerfeld, Cheryl A.

    2016-01-01

    The antiquity and global abundance of the enzyme, RuBisCO, attests to the crucial and longstanding role it has played in the biogeochemical cycles of Earth over billions of years. The counterproductive oxygenase activity of RuBisCO has persisted over billions of years of evolution, despite its competition with the carboxylase activity necessary for carbon fixation, yet hypotheses regarding the selective pressures governing RuBisCO evolution have been limited to speculation. Here we report the resurrection and biochemical characterization of ancestral RuBisCOs, dating back to over one billion years ago (Gyr ago). Our findings provide an ancient point of reference revealing divergent evolutionary paths taken by eukaryotic homologues towards improved specificity for CO2, versus the evolutionary emphasis on increased rates of carboxylation observed in bacterial homologues. Consistent with these distinctions, in vivo analysis reveals the propensity of ancestral RuBisCO to be encapsulated into modern-day carboxysomes, bacterial organelles central to the cyanobacterial CO2 concentrating mechanism. PMID:26790750

  14. Biochemical characterization of predicted Precambrian RuBisCO.

    PubMed

    Shih, Patrick M; Occhialini, Alessandro; Cameron, Jeffrey C; Andralojc, P John; Parry, Martin A J; Kerfeld, Cheryl A

    2016-01-01

    The antiquity and global abundance of the enzyme, RuBisCO, attests to the crucial and longstanding role it has played in the biogeochemical cycles of Earth over billions of years. The counterproductive oxygenase activity of RuBisCO has persisted over billions of years of evolution, despite its competition with the carboxylase activity necessary for carbon fixation, yet hypotheses regarding the selective pressures governing RuBisCO evolution have been limited to speculation. Here we report the resurrection and biochemical characterization of ancestral RuBisCOs, dating back to over one billion years ago (Gyr ago). Our findings provide an ancient point of reference revealing divergent evolutionary paths taken by eukaryotic homologues towards improved specificity for CO2, versus the evolutionary emphasis on increased rates of carboxylation observed in bacterial homologues. Consistent with these distinctions, in vivo analysis reveals the propensity of ancestral RuBisCO to be encapsulated into modern-day carboxysomes, bacterial organelles central to the cyanobacterial CO2 concentrating mechanism. PMID:26790750

  15. Evolving Methanococcoides burtonii archaeal Rubisco for improved photosynthesis and plant growth

    PubMed Central

    Wilson, Robert H.; Alonso, Hernan; Whitney, Spencer M.

    2016-01-01

    In photosynthesis Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyses the often rate limiting CO2-fixation step in the Calvin cycle. This makes Rubisco both the gatekeeper for carbon entry into the biosphere and a target for functional improvement to enhance photosynthesis and plant growth. Encumbering the catalytic performance of Rubisco is its highly conserved, complex catalytic chemistry. Accordingly, traditional efforts to enhance Rubisco catalysis using protracted “trial and error” protein engineering approaches have met with limited success. Here we demonstrate the versatility of high throughput directed (laboratory) protein evolution for improving the carboxylation properties of a non-photosynthetic Rubisco from the archaea Methanococcoides burtonii. Using chloroplast transformation in the model plant Nicotiana tabacum (tobacco) we confirm the improved forms of M. burtonii Rubisco increased photosynthesis and growth relative to tobacco controls producing wild-type M. burtonii Rubisco. Our findings indicate continued directed evolution of archaeal Rubisco offers new potential for enhancing leaf photosynthesis and plant growth. PMID:26926260

  16. Expanding knowledge of the Rubisco kinetics variability in plant species: environmental and evolutionary trends.

    PubMed

    Galmés, Jeroni; Kapralov, Maxim V; Andralojc, P John; Conesa, Miquel À; Keys, Alfred J; Parry, Martin A J; Flexas, Jaume

    2014-09-01

    The present study characterizes the kinetic properties of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from 28 terrestrial plant species, representing different phylogenetic lineages, environmental adaptations and photosynthetic mechanisms. Our findings confirm that past atmospheric CO(2)/O(2) ratio changes and present environmental pressures have influenced Rubisco kinetics. One evolutionary adaptation to a decreasing atmospheric CO(2)/O(2) ratio has been an increase in the affinity of Rubisco for CO(2) (Kc falling), and a consequent decrease in the velocity of carboxylation (kcat (c)), which in turn has been ameliorated by an increase in the proportion of leaf protein accounted by Rubisco. The trade-off between K(c) and k(cat)(c) was not universal among the species studied and deviations from this relationship occur in extant forms of Rubisco. In species adapted to particular environments, including carnivorous plants, crassulacean acid metabolism species and C(3) plants from aquatic and arid habitats, Rubisco has evolved towards increased efficiency, as demonstrated by a higher k(cat)(c)/K(c) ratio. This variability in kinetics was related to the amino acid sequence of the Rubisco large subunit. Phylogenetic analysis identified 13 residues under positive selection during evolution towards specific Rubisco kinetic parameters. This crucial information provides candidate amino acid replacements, which could be implemented to optimize crop photosynthesis under a range of environmental conditions. PMID:24689692

  17. Evolving Methanococcoides burtonii archaeal Rubisco for improved photosynthesis and plant growth.

    PubMed

    Wilson, Robert H; Alonso, Hernan; Whitney, Spencer M

    2016-01-01

    In photosynthesis Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) catalyses the often rate limiting CO2-fixation step in the Calvin cycle. This makes Rubisco both the gatekeeper for carbon entry into the biosphere and a target for functional improvement to enhance photosynthesis and plant growth. Encumbering the catalytic performance of Rubisco is its highly conserved, complex catalytic chemistry. Accordingly, traditional efforts to enhance Rubisco catalysis using protracted "trial and error" protein engineering approaches have met with limited success. Here we demonstrate the versatility of high throughput directed (laboratory) protein evolution for improving the carboxylation properties of a non-photosynthetic Rubisco from the archaea Methanococcoides burtonii. Using chloroplast transformation in the model plant Nicotiana tabacum (tobacco) we confirm the improved forms of M. burtonii Rubisco increased photosynthesis and growth relative to tobacco controls producing wild-type M. burtonii Rubisco. Our findings indicate continued directed evolution of archaeal Rubisco offers new potential for enhancing leaf photosynthesis and plant growth. PMID:26926260

  18. Expanding knowledge of the Rubisco kinetics variability in plant species: environmental and evolutionary trends.

    PubMed

    Galmés, Jeroni; Kapralov, Maxim V; Andralojc, P John; Conesa, Miquel À; Keys, Alfred J; Parry, Martin A J; Flexas, Jaume

    2014-09-01

    The present study characterizes the kinetic properties of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from 28 terrestrial plant species, representing different phylogenetic lineages, environmental adaptations and photosynthetic mechanisms. Our findings confirm that past atmospheric CO(2)/O(2) ratio changes and present environmental pressures have influenced Rubisco kinetics. One evolutionary adaptation to a decreasing atmospheric CO(2)/O(2) ratio has been an increase in the affinity of Rubisco for CO(2) (Kc falling), and a consequent decrease in the velocity of carboxylation (kcat (c)), which in turn has been ameliorated by an increase in the proportion of leaf protein accounted by Rubisco. The trade-off between K(c) and k(cat)(c) was not universal among the species studied and deviations from this relationship occur in extant forms of Rubisco. In species adapted to particular environments, including carnivorous plants, crassulacean acid metabolism species and C(3) plants from aquatic and arid habitats, Rubisco has evolved towards increased efficiency, as demonstrated by a higher k(cat)(c)/K(c) ratio. This variability in kinetics was related to the amino acid sequence of the Rubisco large subunit. Phylogenetic analysis identified 13 residues under positive selection during evolution towards specific Rubisco kinetic parameters. This crucial information provides candidate amino acid replacements, which could be implemented to optimize crop photosynthesis under a range of environmental conditions.

  19. Kranz and single-cell forms of C4 plants in the subfamily Suaedoideae show kinetic C4 convergence for PEPC and Rubisco with divergent amino acid substitutions

    PubMed Central

    Rosnow, Josh J.; Evans, Marc A.; Kapralov, Maxim V.; Cousins, Asaph B.; Edwards, Gerald E.; Roalson, Eric H.

    2015-01-01

    The two carboxylation reactions performed by phosphoenolpyruvate carboxylase (PEPC) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) are vital in the fixation of inorganic carbon for C4 plants. The abundance of PEPC is substantially elevated in C4 leaves, while the location of Rubisco is restricted to one of two chloroplast types. These differences compared with C3 leaves have been shown to result in convergent enzyme optimization in some C4 species. Investigation into the kinetic properties of PEPC and Rubisco from Kranz C4, single cell C4, and C3 species in Chenopodiaceae s. s. subfamily Suaedoideae showed that these major carboxylases in C4 Suaedoideae species lack the same mutations found in other C4 systems which have been examined; but still have similar convergent kinetic properties. Positive selection analysis on the N-terminus of PEPC identified residues 364 and 368 to be under positive selection with a posterior probability >0.99 using Bayes empirical Bayes. Compared with previous analyses on other C4 species, PEPC from C4 Suaedoideae species have different convergent amino acids that result in a higher K m for PEP and malate tolerance compared with C3 species. Kinetic analysis of Rubisco showed that C4 species have a higher catalytic efficiency of Rubisco (k catc in mol CO2 mol–1 Rubisco active sites s–1), despite lacking convergent substitutions in the rbcL gene. The importance of kinetic changes to the two-carboxylation reactions in C4 leaves related to amino acid selection is discussed. PMID:26417023

  20. Functional metagenomic selection of RubisCOs from uncultivated bacteria

    USGS Publications Warehouse

    Varaljay, Vanessa A; Satagopan, Sriram; North, Justin A.; Witteveen, Briana; Dourado, Manuella N.; Anantharaman, Karthik; Arbing, Mark A.; McCann, Shelley; Oremland, Ronald S.; Banfield, Jillian F.; Wrighton, Kelly C.; Tabita, F. Robert

    2016-01-01

    Ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) is a critical yet severely inefficient enzyme that catalyses the fixation of virtually all of the carbon found on Earth. Here, we report a functional metagenomic selection that recovers physiologically active RubisCO molecules directly from uncultivated and largely unknown members of natural microbial communities. Selection is based on CO2-dependent growth in a host strain capable of expressing environmental deoxyribonucleic acid (DNA), precluding the need for pure cultures or screening of recombinant clones for enzymatic activity. Seventeen functional RubisCO-encoded sequences were selected using DNA extracted from soil and river autotrophic enrichments, a photosynthetic biofilm and a subsurface groundwater aquifer. Notably, three related form II RubisCOs were recovered which share high sequence similarity with metagenomic scaffolds from uncultivated members of theGallionellaceae family. One of the Gallionellaceae RubisCOs was purified and shown to possessCO2/O2 specificity typical of form II enzymes. X-ray crystallography determined that this enzyme is a hexamer, only the second form II multimer ever solved and the first RubisCO structure obtained from an uncultivated bacterium. Functional metagenomic selection leverages natural biological diversity and billions of years of evolution inherent in environmental communities, providing a new window into the discovery of CO2-fixing enzymes not previously characterized.

  1. Differential Expression of Rubisco in Sporophytes and Gametophytes of Some Marine Macroalgae

    PubMed Central

    Wang, Guangce; Niu, Jianfeng; Zhou, Baicheng

    2011-01-01

    Rubisco (ribulose-1, 5-bisphosphate carboxylase/oxygenase), a key enzyme of photosynthetic CO2 fixation, is one of the most abundant proteins in both higher plants and algae. In this study, the differential expression of Rubisco in sporophytes and gametophytes of four seaweed species — Porphyra yezoensis, P. haitanensis, Bangia fuscopurpurea (Rhodophyte) and Laminaria japonica (Phaeophyceae) — was studied in terms of the levels of transcription, translation and enzyme activity. Results indicated that both the Rubisco content and the initial carboxylase activity were notably higher in algal gametophytes than in the sporophytes, which suggested that the Rubisco content and the initial carboxylase activity were related to the ploidy of the generations of the four algal species. PMID:21283730

  2. Surveying Rubisco Diversity and Temperature Response to Improve Crop Photosynthetic Efficiency1[OPEN

    PubMed Central

    Andralojc, P. John

    2016-01-01

    The threat to global food security of stagnating yields and population growth makes increasing crop productivity a critical goal over the coming decades. One key target for improving crop productivity and yields is increasing the efficiency of photosynthesis. Central to photosynthesis is Rubisco, which is a critical but often rate-limiting component. Here, we present full Rubisco catalytic properties measured at three temperatures for 75 plants species representing both crops and undomesticated plants from diverse climates. Some newly characterized Rubiscos were naturally “better” compared to crop enzymes and have the potential to improve crop photosynthetic efficiency. The temperature response of the various catalytic parameters was largely consistent across the diverse range of species, though absolute values showed significant variation in Rubisco catalysis, even between closely related species. An analysis of residue differences among the species characterized identified a number of candidate amino acid substitutions that will aid in advancing engineering of improved Rubisco in crop systems. This study provides new insights on the range of Rubisco catalysis and temperature response present in nature, and provides new information to include in models from leaf to canopy and ecosystem scale. PMID:27342312

  3. Photosynthetic characterization of Rubisco transplantomic lines reveals alterations on photochemistry and mesophyll conductance.

    PubMed

    Galmés, Jeroni; Perdomo, Juan Alejandro; Flexas, Jaume; Whitney, Spencer M

    2013-07-01

    Improving Rubisco catalysis is considered a promising way to enhance C3-photosynthesis and photosynthetic water use efficiency (WUE) provided the introduced changes have little or no impact on other processes affecting photosynthesis such as leaf photochemistry or leaf CO2 diffusion conductances. However, the extent to which the factors affecting photosynthetic capacity are co-regulated is unclear. The aim of the present study was to characterize the photochemistry and CO2 transport processes in the leaves of three transplantomic tobacco genotypes expressing hybrid Rubisco isoforms comprising different Flaveria L-subunits that show variations in catalysis and differing trade-offs between the amount of Rubisco and its activation state. Stomatal conductance (g s) in each transplantomic tobacco line matched wild-type, while their photochemistry showed co-regulation with the variations in Rubisco catalysis. A tight co-regulation was observed between Rubisco activity and mesophyll conductance (g m) that was independent of g s thus producing plants with varying g m/g s ratios. Since the g m/g s ratio has been shown to positively correlate with intrinsic WUE, the present results suggest that altering photosynthesis by modifying Rubisco catalysis may also be useful for targeting WUE.

  4. Rubisco activase is a key regulator of non-steady-state photosynthesis at any leaf temperature and, to a lesser extent, of steady-state photosynthesis at high temperature.

    PubMed

    Yamori, Wataru; Masumoto, Chisato; Fukayama, Hiroshi; Makino, Amane

    2012-09-01

    The role of Rubisco activase in steady-state and non-steady-state photosynthesis was analyzed in wild-type (Oryza sativa) and transgenic rice that expressed different amounts of Rubisco activase. Below 25°C, the Rubisco activation state and steady-state photosynthesis were only affected when Rubisco activase was reduced by more than 70%. However, at 40°C, smaller reductions in Rubisco activase content were linked to a reduced Rubisco activation state and steady-state photosynthesis. As a result, overexpression of maize Rubisco activase in rice did not lead to an increase of the Rubisco activation state, nor to an increase in photosynthetic rate below 25°C, but had a small stimulatory effect at 40°C. On the other hand, the rate at which photosynthesis approached the steady state following an increase in light intensity was rapid in Rubisco activase-overexpressing plants, intermediate in the wild-type, and slowest in antisense plants at any leaf temperature. In Rubisco activase-overexpressing plants, Rubisco activation state at low light was maintained at higher levels than in the wild-type. Thus, rapid regulation by Rubisco activase following an increase in light intensity and/or maintenance of a high Rubisco activation state at low light would result in a rapid increase in Rubisco activation state and photosynthetic rate following an increase in light intensity. It is concluded that Rubisco activase plays an important role in the regulation of non-steady-state photosynthesis at any leaf temperature and, to a lesser extent, of steady-state photosynthesis at high temperature.

  5. A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling.

    PubMed

    Galmés, Jeroni; Hermida-Carrera, Carmen; Laanisto, Lauri; Niinemets, Ülo

    2016-09-01

    The present study provides a synthesis of the in vitro and in vivo temperature responses of Rubisco Michaelis-Menten constants for CO2 (Kc) and O2 (Ko), specificity factor (Sc,o) and maximum carboxylase turnover rate (kcatc) for 49 species from all the main photosynthetic kingdoms of life. Novel correction routines were developed for in vitro data to remove the effects of study-to-study differences in Rubisco assays. The compilation revealed differences in the energy of activation (∆Ha) of Rubisco kinetics between higher plants and other photosynthetic groups, although photosynthetic bacteria and algae were under-represented and very few species have been investigated so far. Within plants, the variation in Rubisco temperature responses was related to species' climate and photosynthetic mechanism, with differences in ∆Ha for kcatc among C3 plants from cool and warm environments, and in ∆Ha for kcatc and Kc among C3 and C4 plants. A negative correlation was observed among ∆Ha for Sc/o and species' growth temperature for all data pooled, supporting the convergent adjustment of the temperature sensitivity of Rubisco kinetics to species' thermal history. Simulations of the influence of varying temperature dependences of Rubisco kinetics on Rubisco-limited photosynthesis suggested improved photosynthetic performance of C3 plants from cool habitats at lower temperatures, and C3 plants from warm habitats at higher temperatures, especially at higher CO2 concentration. Thus, variation in Rubisco kinetics for different groups of photosynthetic organisms might need consideration to improve prediction of photosynthesis in future climates. Comparisons between in vitro and in vivo data revealed common trends, but also highlighted a large variability among both types of Rubisco kinetics currently used to simulate photosynthesis, emphasizing the need for more experimental work to fill in the gaps in Rubisco datasets and improve scaling from enzyme kinetics to realized

  6. A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling.

    PubMed

    Galmés, Jeroni; Hermida-Carrera, Carmen; Laanisto, Lauri; Niinemets, Ülo

    2016-09-01

    The present study provides a synthesis of the in vitro and in vivo temperature responses of Rubisco Michaelis-Menten constants for CO2 (Kc) and O2 (Ko), specificity factor (Sc,o) and maximum carboxylase turnover rate (kcatc) for 49 species from all the main photosynthetic kingdoms of life. Novel correction routines were developed for in vitro data to remove the effects of study-to-study differences in Rubisco assays. The compilation revealed differences in the energy of activation (∆Ha) of Rubisco kinetics between higher plants and other photosynthetic groups, although photosynthetic bacteria and algae were under-represented and very few species have been investigated so far. Within plants, the variation in Rubisco temperature responses was related to species' climate and photosynthetic mechanism, with differences in ∆Ha for kcatc among C3 plants from cool and warm environments, and in ∆Ha for kcatc and Kc among C3 and C4 plants. A negative correlation was observed among ∆Ha for Sc/o and species' growth temperature for all data pooled, supporting the convergent adjustment of the temperature sensitivity of Rubisco kinetics to species' thermal history. Simulations of the influence of varying temperature dependences of Rubisco kinetics on Rubisco-limited photosynthesis suggested improved photosynthetic performance of C3 plants from cool habitats at lower temperatures, and C3 plants from warm habitats at higher temperatures, especially at higher CO2 concentration. Thus, variation in Rubisco kinetics for different groups of photosynthetic organisms might need consideration to improve prediction of photosynthesis in future climates. Comparisons between in vitro and in vivo data revealed common trends, but also highlighted a large variability among both types of Rubisco kinetics currently used to simulate photosynthesis, emphasizing the need for more experimental work to fill in the gaps in Rubisco datasets and improve scaling from enzyme kinetics to realized

  7. A compendium of temperature responses of Rubisco kinetic traits: variability among and within photosynthetic groups and impacts on photosynthesis modeling

    PubMed Central

    Galmés, Jeroni; Hermida-Carrera, Carmen; Laanisto, Lauri; Niinemets, Ülo

    2016-01-01

    The present study provides a synthesis of the in vitro and in vivo temperature responses of Rubisco Michaelis–Menten constants for CO2 (Kc) and O2 (Ko), specificity factor (Sc,o) and maximum carboxylase turnover rate (kcatc) for 49 species from all the main photosynthetic kingdoms of life. Novel correction routines were developed for in vitro data to remove the effects of study-to-study differences in Rubisco assays. The compilation revealed differences in the energy of activation (∆Ha) of Rubisco kinetics between higher plants and other photosynthetic groups, although photosynthetic bacteria and algae were under-represented and very few species have been investigated so far. Within plants, the variation in Rubisco temperature responses was related to species’ climate and photosynthetic mechanism, with differences in ∆Ha for kcatc among C3 plants from cool and warm environments, and in ∆Ha for kcatc and Kc among C3 and C4 plants. A negative correlation was observed among ∆Ha for Sc/o and species’ growth temperature for all data pooled, supporting the convergent adjustment of the temperature sensitivity of Rubisco kinetics to species’ thermal history. Simulations of the influence of varying temperature dependences of Rubisco kinetics on Rubisco-limited photosynthesis suggested improved photosynthetic performance of C3 plants from cool habitats at lower temperatures, and C3 plants from warm habitats at higher temperatures, especially at higher CO2 concentration. Thus, variation in Rubisco kinetics for different groups of photosynthetic organisms might need consideration to improve prediction of photosynthesis in future climates. Comparisons between in vitro and in vivo data revealed common trends, but also highlighted a large variability among both types of Rubisco kinetics currently used to simulate photosynthesis, emphasizing the need for more experimental work to fill in the gaps in Rubisco datasets and improve scaling from enzyme kinetics to

  8. Molecular Evolution of the Substrate Specificity of Chloroplastic Aldolases/Rubisco Lysine Methyltransferases in Plants.

    PubMed

    Ma, Sheng; Martin-Laffon, Jacqueline; Mininno, Morgane; Gigarel, Océane; Brugière, Sabine; Bastien, Olivier; Tardif, Marianne; Ravanel, Stéphane; Alban, Claude

    2016-04-01

    Rubisco and fructose-1,6-bisphosphate aldolases (FBAs) are involved in CO2 fixation in chloroplasts. Both enzymes are trimethylated at a specific lysine residue by the chloroplastic protein methyltransferase LSMT. Genes coding LSMT are present in all plant genomes but the methylation status of the substrates varies in a species-specific manner. For example, chloroplastic FBAs are naturally trimethylated in both Pisum sativum and Arabidopsis thaliana, whereas the Rubisco large subunit is trimethylated only in the former species. The in vivo methylation status of aldolases and Rubisco matches the catalytic properties of AtLSMT and PsLSMT, which are able to trimethylate FBAs or FBAs and Rubisco, respectively. Here, we created chimera and site-directed mutants of monofunctional AtLSMT and bifunctional PsLSMT to identify the molecular determinants responsible for substrate specificity. Our results indicate that the His-Ala/Pro-Trp triad located in the central part of LSMT enzymes is the key motif to confer the capacity to trimethylate Rubisco. Two of the critical residues are located on a surface loop outside the methyltransferase catalytic site. We observed a strict correlation between the presence of the triad motif and the in vivo methylation status of Rubisco. The distribution of the motif into a phylogenetic tree further suggests that the ancestral function of LSMT was FBA trimethylation. In a recent event during higher plant evolution, this function evolved in ancestors of Fabaceae, Cucurbitaceae, and Rosaceae to include Rubisco as an additional substrate to the archetypal enzyme. Our study provides insight into mechanisms by which SET-domain protein methyltransferases evolve new substrate specificity. PMID:26785049

  9. Adaptive signals in algal Rubisco reveal a history of ancient atmospheric carbon dioxide.

    PubMed

    Young, J N; Rickaby, R E M; Kapralov, M V; Filatov, D A

    2012-02-19

    Rubisco, the most abundant enzyme on the Earth and responsible for all photosynthetic carbon fixation, is often thought of as a highly conserved and sluggish enzyme. Yet, different algal Rubiscos demonstrate a range of kinetic properties hinting at a history of evolution and adaptation. Here, we show that algal Rubisco has indeed evolved adaptively during ancient and distinct geological periods. Using DNA sequences of extant marine algae of the red and Chromista lineage, we define positive selection within the large subunit of Rubisco, encoded by rbcL, to occur basal to the radiation of modern marine groups. This signal of positive selection appears to be responding to changing intracellular concentrations of carbon dioxide (CO(2)) triggered by physiological adaptations to declining atmospheric CO(2). Within the ecologically important Haptophyta (including coccolithophores) and Bacillariophyta (diatoms), positive selection occurred consistently during periods of falling Phanerozoic CO(2) and suggests emergence of carbon-concentrating mechanisms. During the Proterozoic, a strong signal of positive selection after secondary endosymbiosis occurs at the origin of the Chromista lineage (approx. 1.1 Ga), with further positive selection events until 0.41 Ga, implying a significant and continuous decrease in atmospheric CO(2) encompassing the Cryogenian Snowball Earth events. We surmise that positive selection in Rubisco has been caused by declines in atmospheric CO(2) and hence acts as a proxy for ancient atmospheric CO(2).

  10. Identification and characterization of multiple rubisco activases in chemoautotrophic bacteria

    PubMed Central

    Tsai, Yi-Chin Candace; Lapina, Maria Claribel; Bhushan, Shashi; Mueller-Cajar, Oliver

    2015-01-01

    Ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) is responsible for almost all biological CO2 assimilation, but forms inhibited complexes with its substrate ribulose-1,5-bisphosphate (RuBP) and other sugar phosphates. The distantly related AAA+ proteins rubisco activase and CbbX remodel inhibited rubisco complexes to effect inhibitor release in plants and α-proteobacteria, respectively. Here we characterize a third class of rubisco activase in the chemolithoautotroph Acidithiobacillus ferrooxidans. Two sets of isoforms of CbbQ and CbbO form hetero-oligomers that function as specific activases for two structurally diverse rubisco forms. Mutational analysis supports a model wherein the AAA+ protein CbbQ functions as motor and CbbO is a substrate adaptor that binds rubisco via a von Willebrand factor A domain. Understanding the mechanisms employed by nature to overcome rubisco's shortcomings will increase our toolbox for engineering photosynthetic carbon dioxide fixation. PMID:26567524

  11. Identification and characterization of multiple rubisco activases in chemoautotrophic bacteria.

    PubMed

    Tsai, Yi-Chin Candace; Lapina, Maria Claribel; Bhushan, Shashi; Mueller-Cajar, Oliver

    2015-01-01

    Ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) is responsible for almost all biological CO2 assimilation, but forms inhibited complexes with its substrate ribulose-1,5-bisphosphate (RuBP) and other sugar phosphates. The distantly related AAA+ proteins rubisco activase and CbbX remodel inhibited rubisco complexes to effect inhibitor release in plants and α-proteobacteria, respectively. Here we characterize a third class of rubisco activase in the chemolithoautotroph Acidithiobacillus ferrooxidans. Two sets of isoforms of CbbQ and CbbO form hetero-oligomers that function as specific activases for two structurally diverse rubisco forms. Mutational analysis supports a model wherein the AAA+ protein CbbQ functions as motor and CbbO is a substrate adaptor that binds rubisco via a von Willebrand factor A domain. Understanding the mechanisms employed by nature to overcome rubisco's shortcomings will increase our toolbox for engineering photosynthetic carbon dioxide fixation. PMID:26567524

  12. Rubisco small-subunit α-helices control pyrenoid formation in Chlamydomonas.

    PubMed

    Meyer, Moritz T; Genkov, Todor; Skepper, Jeremy N; Jouhet, Juliette; Mitchell, Madeline C; Spreitzer, Robert J; Griffiths, Howard

    2012-11-20

    The pyrenoid is a subcellular microcompartment in which algae sequester the primary carboxylase, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). The pyrenoid is associated with a CO(2)-concentrating mechanism (CCM), which improves the operating efficiency of carbon assimilation and overcomes diffusive limitations in aquatic photosynthesis. Using the model alga Chlamydomonas reinhardtii, we show that pyrenoid formation, Rubisco aggregation, and CCM activity relate to discrete regions of the Rubisco small subunit (SSU). Specifically, pyrenoid occurrence was shown to be conditioned by the amino acid composition of two surface-exposed α-helices of the SSU: higher plant-like helices knock out the pyrenoid, whereas native algal helices establish a pyrenoid. We have also established that pyrenoid integrity was essential for the operation of an active CCM. With the algal CCM being functionally analogous to the terrestrial C(4) pathway in higher plants, such insights may offer a route toward transforming algal and higher plant productivity for the future.

  13. The rate of photosynthesis remains relatively high at moderately high temperatures in Arabidopsis thaliana rca mutant expressing thermostable chimeric Rubisco activase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rate of photosynthesis declines at moderately high temperatures (30-42 deg C) in temperate plants like Arabidopsis. The decline is due to deactivation of Rubisco which in turn is due to a reduced ability of activase to activate Rubisco (Crafts-Brandner and Salvucci, PNAS 97:13430-13435, 2000). W...

  14. The rate of Photosynthesis remains relatively high at moderately high temperatures in Arabidopsis thaliana rca mutant expressing thermostable chimeric Rubisco Activase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rate of photosynthesis declines at moderately high temperatures (30-42 deg C) in temperate plants like Arabidopsis. The decline is due to deactivation of Rubisco which in turn is due to a reduced ability of activase to activate Rubisco (Crafts-Brandner and Salvucci, PNAS 97:13430-13435, 2000). W...

  15. Characterization of a barley Rubisco activase gene promoter

    SciTech Connect

    Strickland, J.A.; Rundle, S.J.; Zielinski, R. )

    1990-05-01

    Barley Rubisco Activase (Rca) is a nuclear encoded chloroplast enzyme that activates Rubisco to catalytic competence. Rca mRNA accumulation in barley is light-regulated; the 5{prime}-flanking region of a highly expressed barley Rca gene (HvRca-1) contains several sequence motifs similar to those found in the promoter of other light-regulated, nuclear genes. We have characterized the cis-acting regulatory regions of HvRca-1 by deletion analysis of the 5{prime} flanking region of a cloned gene. These constructs have been assayed in vitro by gel mobility shift assays, as well as by DNA footprinting. Putative regulatory sequences detected in vitro have also been tested in vivo by constructing chimeric genes consisting of deletion mutant promoters fused to a promoterless {beta}-glucuronidase reporter gene. Comparison of results obtained from complimentary parallel in vitro and in vivo assays of identical promoter deletions have provided information on cis-acting regulatory regions of HvRca-1.

  16. CONSEQUENCES OF ALTERING RUBISCO REGULATION

    SciTech Connect

    Salvucci, Michael

    2013-12-31

    Research examined the thermal stability and propensity for aggregation of wild type and the C- and N-terminally modified forms of activase to determine if loss of activity under heat stress is dependent on protein aggregation. The results showed that 1) loss of activity at high temperature is independent of aggregation; 2) activase with both C- and N-terminal S-Tags are more susceptible to aggregation than wild type activase, 3) aggregation is highly dependent on the concentration of Mg2+ and 4) the ATP analog, ATPgammaS, protects against both thermal inactivation and aggregation.

  17. The mechanism of Rubisco-catalysed oxygenation.

    PubMed

    Tcherkez, Guillaume

    2016-05-01

    Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the cornerstone of photosynthetic carbon assimilation because it catalyses the fixation of CO2 onto ribulose-1,5-bisphosphate (RuBP). The enzyme also catalyses RuBP oxygenation, thereby evolving phosphoglycolate which is recycled along the photorespiratory pathway. Oxygenation is quantitatively important, because under ordinary gaseous conditions, more than one third of RuBP molecules are oxygenated rather than carboxylated. However, contrary to carboxylation, the chemical mechanism of oxygenation is not well known, and little progress has been made since the early 80s. Here, I review recent experimental data that provide some new insights into the reaction mechanism, and carry out simple calculations of kinetic parameters. Isotope effects suggest that oxygenation is less likely initiated by a redox phenomenon (such as superoxide production) and more likely involves concerted chemical events that imply interactions with protons. A possible energy profile of the reaction is drawn which suggests that the generation of the oxygenated reaction intermediate (peroxide) is irreversible. Possible changes in oxygenation-associated rate constants between Rubisco forms are discussed. PMID:26286702

  18. Rubisco decrease is involved in chloroplast protrusion and Rubisco-containing body formation in soybean (Glycine max.) under salt stress.

    PubMed

    He, Yi; Yu, Chenliang; Zhou, Li; Chen, Yue; Liu, Ao; Jin, Junhua; Hong, Jian; Qi, Yanhua; Jiang, Dean

    2014-01-01

    Salt stress often induces declination of net photosynthetic rate (Pn), partially resulted from Rubisco degradation. The chloroplast protrusions (CPs) is one of the pathways of Rubisco exclusion from chloroplasts. To explore the relationship between the Rubisco contents and CPs under salt stress, Pn, maximum photochemical efficiency of PSII (F(v)/F(m)), carboxylation efficiency (CE) and concentration of Rubisco, number of CPs and Rubisco-containing Body (RCBs) were investigated with two differently salt-responding varieties in this experiment. We observed that 150 mM salt treatment resulted in not only significant decrease in Pn, CE and Rubisco content, but also obvious increase in the number of CPs and RCBs in salt-sensitive variety. Under salt stress formation of CPs resulted in production of much more RCBs, which could immigrate into and combine with vacuole. It may be a kind of important mechanism for rapid degradation of Rubisco under salt stress. Our conclusion provides a new sight for how Rubisco can be fast degraded under salt stress.

  19. Transgenic tobacco plants with improved cyanobacterial Rubisco expression but no extra assembly factors grow at near wild-type rates if provided with elevated CO2.

    PubMed

    Occhialini, Alessandro; Lin, Myat T; Andralojc, P John; Hanson, Maureen R; Parry, Martin A J

    2016-01-01

    Introducing a carbon-concentrating mechanism and a faster Rubisco enzyme from cyanobacteria into higher plant chloroplasts may improve photosynthetic performance by increasing the rate of CO2 fixation while decreasing losses caused by photorespiration. We previously demonstrated that tobacco plants grow photoautotrophically using Rubisco from Synechococcus elongatus, although the plants exhibited considerably slower growth than wild-type and required supplementary CO2 . Because of concerns that vascular plant assembly factors may not be adequate for assembly of a cyanobacterial Rubisco, prior transgenic plants included the cyanobacterial chaperone RbcX or the carboxysomal protein CcmM35. Here we show that neither RbcX nor CcmM35 is needed for assembly of active cyanobacterial Rubisco. Furthermore, by altering the gene regulatory sequences on the Rubisco transgenes, cyanobacterial Rubisco expression was enhanced and the transgenic plants grew at near wild-type growth rates, although still requiring elevated CO2 . We performed detailed kinetic characterization of the enzymes produced with and without the RbcX and CcmM35 cyanobacterial proteins. These transgenic plants exhibit photosynthetic characteristics that confirm the predicted benefits of introduction of non-native forms of Rubisco with higher carboxylation rate constants in vascular plants and the potential nitrogen-use efficiency that may be achieved provided that adequate CO2 is available near the enzyme.

  20. Transgenic tobacco plants with improved cyanobacterial Rubisco expression but no extra assembly factors grow at near wild-type rates if provided with elevated CO2.

    PubMed

    Occhialini, Alessandro; Lin, Myat T; Andralojc, P John; Hanson, Maureen R; Parry, Martin A J

    2016-01-01

    Introducing a carbon-concentrating mechanism and a faster Rubisco enzyme from cyanobacteria into higher plant chloroplasts may improve photosynthetic performance by increasing the rate of CO2 fixation while decreasing losses caused by photorespiration. We previously demonstrated that tobacco plants grow photoautotrophically using Rubisco from Synechococcus elongatus, although the plants exhibited considerably slower growth than wild-type and required supplementary CO2 . Because of concerns that vascular plant assembly factors may not be adequate for assembly of a cyanobacterial Rubisco, prior transgenic plants included the cyanobacterial chaperone RbcX or the carboxysomal protein CcmM35. Here we show that neither RbcX nor CcmM35 is needed for assembly of active cyanobacterial Rubisco. Furthermore, by altering the gene regulatory sequences on the Rubisco transgenes, cyanobacterial Rubisco expression was enhanced and the transgenic plants grew at near wild-type growth rates, although still requiring elevated CO2 . We performed detailed kinetic characterization of the enzymes produced with and without the RbcX and CcmM35 cyanobacterial proteins. These transgenic plants exhibit photosynthetic characteristics that confirm the predicted benefits of introduction of non-native forms of Rubisco with higher carboxylation rate constants in vascular plants and the potential nitrogen-use efficiency that may be achieved provided that adequate CO2 is available near the enzyme. PMID:26662726

  1. Characterization of heat-set gels from RuBisCO in comparison to those from other proteins.

    PubMed

    Martin, Anneke H; Nieuwland, Maaike; de Jong, Govardus A H

    2014-11-01

    To anticipate a future shortage in functional proteins, it is important to study the functionality of new alternative protein sources. Native RuBisCO was extracted from spinach, and its gelation behavior was compared to other native proteins from animal and plant origins. Protein gels were analyzed for their mechanical gel properties during small and large deformation and for their microstructure. Heat-induced aggregation and network formation of RuBisCO resulted in gels with unique characteristics compared to, for example, whey protein and egg white protein. Having a very low critical gelling concentration and low denaturation temperature, RuBisCO readily forms a network with a very high gel strength (G', fracture stress), but upon deformation it has a brittle character (low critical strain, low fracture strain). This breakdown behavior can be explained by the dominant role of hydrophobic and hydrogen bonds between RuBisCO molecules during network formation and by the coarse microstructure. RuBisCO was shown to exhibit high potential as a functional ingredient giving opportunities for the design of new textures at low protein concentration. PMID:25314325

  2. Diverse nucleotide compositions and sequence fluctuation in Rubisco protein genes

    NASA Astrophysics Data System (ADS)

    Holden, Todd; Dehipawala, S.; Cheung, E.; Bienaime, R.; Ye, J.; Tremberger, G., Jr.; Schneider, P.; Lieberman, D.; Cheung, T.

    2011-10-01

    The Rubisco protein-enzyme is arguably the most abundance protein on Earth. The biology dogma of transcription and translation necessitates the study of the Rubisco genes and Rubisco-like genes in various species. Stronger correlation of fractal dimension of the atomic number fluctuation along a DNA sequence with Shannon entropy has been observed in the studied Rubisco-like gene sequences, suggesting a more diverse evolutionary pressure and constraints in the Rubisco sequences. The strategy of using metal for structural stabilization appears to be an ancient mechanism, with data from the porphobilinogen deaminase gene in Capsaspora owczarzaki and Monosiga brevicollis. Using the chi-square distance probability, our analysis supports the conjecture that the more ancient Rubisco-like sequence in Microcystis aeruginosa would have experienced very different evolutionary pressure and bio-chemical constraint as compared to Bordetella bronchiseptica, the two microbes occupying either end of the correlation graph. Our exploratory study would indicate that high fractal dimension Rubisco sequence would support high carbon dioxide rate via the Michaelis- Menten coefficient; with implication for the control of the whooping cough pathogen Bordetella bronchiseptica, a microbe containing a high fractal dimension Rubisco-like sequence (2.07). Using the internal comparison of chi-square distance probability for 16S rRNA (~ E-22) versus radiation repair Rec-A gene (~ E-05) in high GC content Deinococcus radiodurans, our analysis supports the conjecture that high GC content microbes containing Rubisco-like sequence are likely to include an extra-terrestrial origin, relative to Deinococcus radiodurans. Similar photosynthesis process that could utilize host star radiation would not compete with radiation resistant process from the biology dogma perspective in environments such as Mars and exoplanets.

  3. Structural Analysis of the Rubisco-Assembly Chaperone RbcX-II from Chlamydomonas reinhardtii

    PubMed Central

    Liu, Cuimin; Hartl, F. Ulrich; Hayer-Hartl, Manajit

    2015-01-01

    The most prevalent form of the Rubisco enzyme is a complex of eight catalytic large subunits (RbcL) and eight regulatory small subunits (RbcS). Rubisco biogenesis depends on the assistance by specific molecular chaperones. The assembly chaperone RbcX stabilizes the RbcL subunits after folding by chaperonin and mediates their assembly to the RbcL8 core complex, from which RbcX is displaced by RbcS to form active holoenzyme. Two isoforms of RbcX are found in eukaryotes, RbcX-I, which is more closely related to cyanobacterial RbcX, and the more distant RbcX-II. The green algae Chlamydomonas reinhardtii contains only RbcX-II isoforms, CrRbcX-IIa and CrRbcX-IIb. Here we solved the crystal structure of CrRbcX-IIa and show that it forms an arc-shaped dimer with a central hydrophobic cleft for binding the C-terminal sequence of RbcL. Like other RbcX proteins, CrRbcX-IIa supports the assembly of cyanobacterial Rubisco in vitro, albeit with reduced activity relative to cyanobacterial RbcX-I. Structural analysis of a fusion protein of CrRbcX-IIa and the C-terminal peptide of RbcL suggests that the peptide binding mode of RbcX-II may differ from that of cyanobacterial RbcX. RbcX homologs appear to have adapted to their cognate Rubisco clients as a result of co-evolution. PMID:26305355

  4. Rubisco small-subunit α-helices control pyrenoid formation in Chlamydomonas

    PubMed Central

    Meyer, Moritz T.; Genkov, Todor; Skepper, Jeremy N.; Jouhet, Juliette; Mitchell, Madeline C.; Spreitzer, Robert J.; Griffiths, Howard

    2012-01-01

    The pyrenoid is a subcellular microcompartment in which algae sequester the primary carboxylase, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). The pyrenoid is associated with a CO2-concentrating mechanism (CCM), which improves the operating efficiency of carbon assimilation and overcomes diffusive limitations in aquatic photosynthesis. Using the model alga Chlamydomonas reinhardtii, we show that pyrenoid formation, Rubisco aggregation, and CCM activity relate to discrete regions of the Rubisco small subunit (SSU). Specifically, pyrenoid occurrence was shown to be conditioned by the amino acid composition of two surface-exposed α-helices of the SSU: higher plant-like helices knock out the pyrenoid, whereas native algal helices establish a pyrenoid. We have also established that pyrenoid integrity was essential for the operation of an active CCM. With the algal CCM being functionally analogous to the terrestrial C4 pathway in higher plants, such insights may offer a route toward transforming algal and higher plant productivity for the future. PMID:23112177

  5. Mobilization of Rubisco and Stroma-Localized Fluorescent Proteins of Chloroplasts to the Vacuole by an ATG Gene-Dependent Autophagic Process1[W][OA

    PubMed Central

    Ishida, Hiroyuki; Yoshimoto, Kohki; Izumi, Masanori; Reisen, Daniel; Yano, Yuichi; Makino, Amane; Ohsumi, Yoshinori; Hanson, Maureen R.; Mae, Tadahiko

    2008-01-01

    During senescence and at times of stress, plants can mobilize needed nitrogen from chloroplasts in leaves to other organs. Much of the total leaf nitrogen is allocated to the most abundant plant protein, Rubisco. While bulk degradation of the cytosol and organelles in plants occurs by autophagy, the role of autophagy in the degradation of chloroplast proteins is still unclear. We have visualized the fate of Rubisco, stroma-targeted green fluorescent protein (GFP) and DsRed, and GFP-labeled Rubisco in order to investigate the involvement of autophagy in the mobilization of stromal proteins to the vacuole. Using immunoelectron microscopy, we previously demonstrated that Rubisco is released from the chloroplast into Rubisco-containing bodies (RCBs) in naturally senescent leaves. When leaves of transgenic Arabidopsis (Arabidopsis thaliana) plants expressing stroma-targeted fluorescent proteins were incubated with concanamycin A to inhibit vacuolar H+-ATPase activity, spherical bodies exhibiting GFP or DsRed fluorescence without chlorophyll fluorescence were observed in the vacuolar lumen. Double-labeled immunoelectron microscopy with anti-Rubisco and anti-GFP antibodies confirmed that the fluorescent bodies correspond to RCBs. RCBs could also be visualized using GFP-labeled Rubisco directly. RCBs were not observed in leaves of a T-DNA insertion mutant in ATG5, one of the essential genes for autophagy. Stroma-targeted DsRed and GFP-ATG8 fusion proteins were observed together in autophagic bodies in the vacuole. We conclude that Rubisco and stroma-targeted fluorescent proteins can be mobilized to the vacuole through an ATG gene-dependent autophagic process without prior chloroplast destruction. PMID:18614709

  6. Mechanistic Diversity in the RuBisCO Superfamily: The Enolase in the Methionine

    SciTech Connect

    Imker,H.; Fedorov, A.; Fedorov, E.; Almo, S.; Gerlt, J.

    2007-01-01

    D-Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO), the most abundant enzyme, is the paradigm member of the recently recognized mechanistically diverse RuBisCO superfamily. The RuBisCO reaction is initiated by abstraction of the proton from C3 of the D-ribulose 1,5-bisphosphate substrate by a carbamate oxygen of carboxylated Lys 201 (spinach enzyme). Heterofunctional homologues of RuBisCO found in species of Bacilli catalyze the tautomerization ('enolization') of 2,3-diketo-5-methylthiopentane 1-phosphate (DK-MTP 1-P) in the methionine salvage pathway in which 5-methylthio-D-ribose (MTR) derived from 5'-methylthioadenosine is converted to methionine [Ashida, H., Saito, Y., Kojima, C., Kobayashi, K., Ogasawara, N., and Yokota, A. (2003) A functional link between RuBisCO-like protein of Bacillus and photosynthetic RuBisCO, Science 302, 286-290]. The reaction catalyzed by this 'enolase' is accomplished by abstraction of a proton from C1 of the DK-MTP 1-P substrate to form the tautomerized product, a conjugated enol. Because the RuBisCO- and 'enolase'-catalyzed reactions differ in the regiochemistry of proton abstraction but are expected to share stabilization of an enolate anion intermediate by coordination to an active site Mg{sup 2+}, we sought to establish structure-function relationships for the 'enolase' reaction so that the structural basis for the functional diversity could be established. We determined the stereochemical course of the reaction catalyzed by the 'enolases' from Bacillus subtilis and Geobacillus kaustophilus. Using stereospecifically deuterated samples of an alternate substrate derived from D-ribose (5-OH group instead of the 5-methylthio group in MTR) as well as of the natural DK-MTP 1-P substrate, we determined that the 'enolase'-catalyzed reaction involves abstraction of the 1-proS proton. We also determined the structure of the activated 'enolase' from G. kaustophilus (carboxylated on Lys 173) liganded with Mg{sup 2+} and 2

  7. Structure and expression of nuclear genes encoding rubisco activase. Final technical report

    SciTech Connect

    Zielinski, R.E.

    1994-06-01

    Rubisco activase (Rca) is a soluble chloroplast protein that catalyzes the activation of rubisco, the enzyme that initiates the photosynthetic carbon reduction cycle, to catalytic competency. Rca in barley consists of three polypeptides, one of 46- and two of 42-kDa, but the quaternary structure of the protein is not known. The authors have isolated and completely sequenced 8.8 kb of barley genomic DNA containing two, tandemly oriented activase genes (RcaA and RcaB) and three different cDNAs encoding the 42- and 46-kDa Rca polypeptide isoforms. Genomic Southern blot assays indicate that these sequences represent the entire Rca gene family in barley. Pre-mRNAs transcribed from the RcaA gene are alternatively spliced to give mRNAs encoding both 46- (RcaA1) and 42-kDa (RcaA2) Rca isoforms. The RcaB gene encodes a single polypeptide of 42 kDa. Primer extension and northern blot assays indicate that RcaB mRNA is expressed at a level that is 10- to 100-fold lower than RcaA mRNA. Analyses at the mRNA and protein level showed that Rca gene expression is coordinated by that of the rubisco subunits during barley leaf development.

  8. (Structure and expression of nuclear genes encoding rubisco activase): Progress report

    SciTech Connect

    Not Available

    1989-01-01

    Our first year's activities include: (1) completing a survey of the basic characteristics of activase gene expression in barley; and (2) isolating and structurally characterizing cDNA and genomic DNA sequences encoding activase from barley. Our goal was to determine whether activase mRNA and protein accumulation are coordinated with those of the rubisco subunits. We utilized the first leaves of barley as an experimental system for these studies because they can be used in two ways to study the expression of leaf genes: by following the naturally occurring differentiation of leaf cells, which occurs acropetally along the barley leaf; and by following the photomorphogenesis of etiolated barley seedlings. In the acropetal gradient of leaf cell differentiation, activase mRNA and mRNA and polypeptide expression is tightly coordinated with rubisco subunit mRNA and polypeptide expression. Although we have not measured their precise stoichiometry at each stage of leaf differentiation, activase protein is expressed at the level of about one polypeptide per rubisco holoenzyme in mature regions of the leaf. Coordination of the expression of activase mRNAs and polypeptides indicates that in the barley leaf gradient, activase gene expression is largely controlled at the level of transcription. However, translational controls may play a role in regulating activase expression on a short term basis.

  9. The RUBISCO to Photosystem II Ratio Limits the Maximum Photosynthetic Rate in Picocyanobacteria

    PubMed Central

    Zorz, Jackie K.; Allanach, Jessica R.; Murphy, Cole D.; Roodvoets, Mitchell S.; Campbell, Douglas A.; Cockshutt, Amanda M.

    2015-01-01

    Marine Synechococcus and Prochlorococcus are picocyanobacteria predominating in subtropical, oligotrophic marine environments, a niche predicted to expand with climate change. When grown under common low light conditions Synechococcus WH 8102 and Prochlorococcus MED 4 show similar Cytochrome b6f and Photosystem I contents normalized to Photosystem II content, while Prochlorococcus MIT 9313 has twice the Cytochrome b6f content and four times the Photosystem I content of the other strains. Interestingly, the Prochlorococcus strains contain only one third to one half of the RUBISCO catalytic subunits compared to the marine Synechococcus strain. The maximum Photosystem II electron transport rates were similar for the two Prochlorococcus strains but higher for the marine Synechococcus strain. Photosystem II electron transport capacity is highly correlated to the molar ratio of RUBISCO active sites to Photosystem II but not to the ratio of cytochrome b6f to Photosystem II, nor to the ratio of Photosystem I: Photosystem II. Thus, the catalytic capacity for the rate-limiting step of carbon fixation, the ultimate electron sink, appears to limit electron transport rates. The high abundance of Cytochrome b6f and Photosystem I in MIT 9313, combined with the slower flow of electrons away from Photosystem II and the relatively low level of RUBISCO, are consistent with cyclic electron flow around Photosystem I in this strain. PMID:25658887

  10. Stable Carbon Isotope Discrimination by Form IC Rubisco Enzymes of the Extremely Metabolically Versatile Rhodobacter sphaeroides and Ralstonia eutropha}

    NASA Astrophysics Data System (ADS)

    Thomas, P. J.; Boller, A. J.; Zhao, Z.; Tabita, F. R.; Cavanaugh, C. M.; Scott, K. M.

    2006-12-01

    Variations in the relative amounts of 12C and 13C in microbial biomass can be used to infer the pathway(s) autotrophs use to fix and assimilate dissolved inorganic carbon. Discrimination against 13C by the enzymes catalyzing autotrophic carbon fixation is a major factor dictating biomass stable carbon isotopic compositions (δ13C = {[13C/12Csample/13C/12Cstandard] - 1} × 1000). Five different forms of RubisCO (IA, IB, IC, ID, and II) are utilized by algae and autotrophic bacteria reliant on the Calvin-Benson cycle for carbon fixation. To date, isotope discrimination has been measured for form IA, IB, and II RubisCOs, and their ɛ values (={[12k/13k] - 1} × 1000; 12k and 13k = rates of 12C and 13C fixation) range from 18 to 29‰, explaining the variation in biomass δ13C values of autotrophs utilizing these enzymes. Isotope discrimination by form IC RubisCO has not been measured, despite the presence of this enzyme in many proteobacteria of ecological interest, including marine manganese-oxidizing bacteria, some nitrifying and nitrogen-fixing bacteria, and extremely metabolically versatile organisms such as Rhodobacter sphaeroides and Ralstonia eutropha. The purpose of this work was to determine the ɛ values for form IC RubisCO enzymes from R. sphaeroides and R. eutropha. Recombinant form IC RubisCOs were purified by conventional column chromatography procedures. Assay conditions (pH, dissolved inorganic carbon concentration) were tested to determine which parameters were conducive to the high rates of carbon fixation necessary for ɛ determination. Under standard conditions (pH 8.5 and 5 mM DIC), form IC RubisCO activities were sufficient for ɛ determination. Experiments are currently being conducted to measure the ɛ values of these enzymes. Sampling the full phylogenetic breadth of RubisCO enzymes for isotopic discrimination makes it possible to constrain the range of δ13C values of organisms fixing carbon via the Calvin-Benson cycle. These results are

  11. Rubisco activase and wheat productivity under heat stress conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rubisco activase (RCA) constrains the photosynthetic potential of plants at high temperature (heat stress). We hypothesized that endogenous levels of RCA could serve as an important determinant of plant productivity under heat stress conditions. In this study, we investigated the possible relation...

  12. Regulation of Ribulose-1,5-bisphosphate Carboxylase/Oxygenase (Rubisco) Activase

    PubMed Central

    Hazra, Suratna; Henderson, J. Nathan; Liles, Kevin; Hilton, Matthew T.; Wachter, Rebekka M.

    2015-01-01

    In many photosynthetic organisms, tight-binding Rubisco inhibitors are released by the motor protein Rubisco activase (Rca). In higher plants, Rca plays a pivotal role in regulating CO2 fixation. Here, the ATPase activity of 0.005 mm tobacco Rca was monitored under steady-state conditions, and global curve fitting was utilized to extract kinetic constants. The kcat was best fit by 22.3 ± 4.9 min−1, the Km for ATP by 0.104 ± 0.024 mm, and the Ki for ADP by 0.037 ± 0.007 mm. Without ADP, the Hill coefficient for ATP hydrolysis was extracted to be 1.0 ± 0.1, indicating noncooperative behavior of homo-oligomeric Rca assemblies. However, the addition of ADP was shown to introduce positive cooperativity between two or more subunits (Hill coefficient 1.9 ± 0.2), allowing for regulation via the prevailing ATP/ADP ratio. ADP-mediated activation was not observed, although larger amounts led to competitive product inhibition of hydrolytic activity. The catalytic efficiency increased 8.4-fold upon cooperative binding of a second magnesium ion (Hill coefficient 2.5 ± 0.5), suggesting at least three conformational states (ATP-bound, ADP-bound, and empty) within assemblies containing an average of about six subunits. The addition of excess Rubisco (24:1, L8S8/Rca6) and crowding agents did not modify catalytic rates. However, high magnesium provided for thermal Rca stabilization. We propose that magnesium mediates the formation of closed hexameric toroids capable of high turnover rates and amenable to allosteric regulation. We suggest that in vivo, the Rca hydrolytic activity is tuned by fluctuating [Mg2+] in response to changes in available light. PMID:26283786

  13. The single-process biochemical reaction of Rubisco: a unified theory and model with the effects of irradiance, CO₂ and rate-limiting step on the kinetics of C₃ and C₄ photosynthesis from gas exchange.

    PubMed

    Farazdaghi, Hadi

    2011-02-01

    Photosynthesis is the origin of oxygenic life on the planet, and its models are the core of all models of plant biology, agriculture, environmental quality and global climate change. A theory is presented here, based on single process biochemical reactions of Rubisco, recognizing that: In the light, Rubisco activase helps separate Rubisco from the stored ribulose-1,5-bisphosphate (RuBP), activates Rubisco with carbamylation and addition of Mg²(+), and then produces two products, in two steps: (Step 1) Reaction of Rubisco with RuBP produces a Rubisco-enediol complex, which is the carboxylase-oxygenase enzyme (Enco) and (Step 2) Enco captures CO₂ and/or O₂ and produces intermediate products leading to production and release of 3-phosphoglycerate (PGA) and Rubisco. PGA interactively controls (1) the carboxylation-oxygenation, (2) electron transport, and (3) triosephosphate pathway of the Calvin-Benson cycle that leads to the release of glucose and regeneration of RuBP. Initially, the total enzyme participates in the two steps of the reaction transitionally and its rate follows Michaelis-Menten kinetics. But, for a continuous steady state, Rubisco must be divided into two concurrently active segments for the two steps. This causes a deviation of the steady state from the transitional rate. Kinetic models are developed that integrate the transitional and the steady state reactions. They are tested and successfully validated with verifiable experimental data. The single-process theory is compared to the widely used two-process theory of Farquhar et al. (1980. Planta 149, 78-90), which assumes that the carboxylation rate is either Rubisco-limited at low CO₂ levels such as CO₂ compensation point, or RuBP regeneration-limited at high CO₂. Since the photosynthesis rate cannot increase beyond the two-process theory's Rubisco limit at the CO₂ compensation point, net photosynthesis cannot increase above zero in daylight, and since there is always respiration at

  14. Electron flow to oxygen in higher plants and algae: rates and control of direct photoreduction (Mehler reaction) and rubisco oxygenase.

    PubMed

    Badger, M R; von Caemmerer, S; Ruuska, S; Nakano, H

    2000-10-29

    mechanism and under conditions that are clearly limiting with respect to inorganic carbon supply. A part explanation for this could be that many algal rubsicos have considerably different oxygenase kinetic properties and exhibit far less oxygenase activity in air. This would lead to the conclusion that perhaps a greater proportion of the observed O2 uptake may be due to a Mehler reaction and less to rubisco, compared with C3 plants. In contrast to algae and higher plants, cyanobacteria appear to have a high capacity for Mehler O2 uptake, which appears to be not well coupled or limited by ATP consumption. It is likely that in all higher plants and algae, which have a well-developed non-photochemical quenching mechanism, non-radiative energy dissipation is the major mechanism for dissipating excess photons absorbed by the light-harvesting complexes under stressful conditions. However, for cyanobacteria, with a lack of significant non-photochemical quenching, the situation may well be different. PMID:11127997

  15. Quantum chemical modeling of the kinetic isotope effect of the carboxylation step in RuBisCO.

    PubMed

    Götze, Jan Philipp; Saalfrank, Peter

    2012-05-01

    Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), the most important enzyme for the assimilation of carbon into biomass, features a well-known isotope effect with regards to the CO(2) carbon atom. This kinetic isotope effect α = k(12)/k(13) for the carboxylation step of the RuBisCO reaction sequence, and its microscopic origin, was investigated with the help of cluster models and quantum chemical methods [B3LYP/6-31G(d,p)]. We use a recently proposed model for the RuBisCO active site, in which a water molecule remains close to the reaction center during carboxylation of ribulose-1,5-bisphosphate [B. Kannappan, J.E. Gready, J. Am. Chem. Soc. 130 (2008), 15063]. Alternative active-site models and/or computational approaches were also tested. An isotope effect alpha for carboxylation is found, which is reasonably close to the one measured for the overall reaction, and which originates from a simple frequency shift of the bending vibration of (12)CO(2) compared to (13)CO(2). The latter is the dominant mode for the product formation at the transition state.

  16. Role of the Rubisco small subunit. Final report for period May 1, 1997--April 30,2000

    SciTech Connect

    Spreitzer, Robert J.

    2000-10-04

    CO{sub 2} and O{sub 2} are mutually competitive at the active site of ribulose-1,5-biphosphate (RuBP) carboxylase/oxygenase (Rubisco). Rubisco contains two subunits, each present in eight copies. The 15-kD small subunit is coded by a family of nuclear RbcS genes. Until now, the role of the small subunit in Rubisco structure or catalytic efficiency is not known. Because of other work in eliminating the two RbcS genes in the green algo Chlamydomonas reinhardtii, it is now possible to address questions about the structure-function relationships of the eukaryotic small subunit. There are three specific aims in this project: (1) Alanine scanning mutagenesis is being used to dissect the importance of the {beta}A/{beta}B loop, a feature unique to the eukaryotic small subunit. (2) Random mutagenesis is being used to identify additional residues or regions of the small subunit that are important for holoenzyme assembly and function. (3) Attempts are being made to express foreign small subunits in Chlamydomonas to examine the contribution of small subunits to holoenzyme assembly, catalytic efficiency, and CO{sub 2}/O{sub 2} specificity.

  17. Relationship between rubisco sulfhydryl content and relative sensitivity of potato cultivars to ozone

    SciTech Connect

    Enyedi, A.J.; Pell, E.J. )

    1989-04-01

    Ozone (O{sub 3}) induced a reduction in quantity of rubisco in potato foliage. In vitro, O{sub 3} predisposed purified rubisco to elevated proteolysis; reagents which protected sulfhydryl (SH) groups suppressed this effect. We hypothesized that rubisco SH content correlated directly with foliar O{sub 3} sensitivity. Rubisco was purified from Solanum tuberosum L. O{sub 3}-tolerant cv. Superior (SP) and Norgold Russet (NR), and O{sub 3}-susceptible cv. Norland (NL) and Cherokee (CK). When native rubisco was titrated with DTNB, protein of NL contained 1.33 and 1.26 times more SH groups than SP and NR, respectively. Rubisco from CK also contained more SH groups than SP and NR, but the difference was not significant. Rubisco of SP, NR and CK denatured by SDS exhibited identical number of SH groups, however, NL exhibited 1.15 times more SH groups. The greater number of SH groups in rubisco from NL versus SP and NR may explain its relative sensitivity to ozone. The role of SH groups in ozone-sensitivity of CK will require further study.

  18. The kinetics of conformation change as determinant of Rubisco's specificity.

    PubMed

    Schlitter, J; Wildner, G F

    2000-01-01

    The molecular basis of Rubisco's specificity is investigated in terms of the structure and kinetics of the enzyme. We propose that the rates of the conformational changes (closing/opening) of the binding niche exert a crucial influence on apparent binding rates and the enzyme's specificity. An extended reaction scheme for binding and conformational kinetics is presented and expressed in a mathematical model. The closed conformation, known from X-ray structures, is assumed to be necessary for binding of the gaseous substrates (carbon dioxide and oxygen) and for catalysis. Opening the niche interrupts catalysis and enables a fast exchange of those molecules between the internal cavity and the surrounding solvent. Our model predicts that specificity of Rubisco for CO(2) increases with the rate by which the niche opens. This is due to the fact that binding of the carbon dioxide is faster than oxygen binding, which is hampered by spin inversion. The apparent rate of carbon dioxide binding correlates with the repetition rate of the conformational change, and the rate of oxygen binding with the probability of the closed state. PMID:16228466

  19. A repeat protein links Rubisco to form the eukaryotic carbon-concentrating organelle.

    PubMed

    Mackinder, Luke C M; Meyer, Moritz T; Mettler-Altmann, Tabea; Chen, Vivian K; Mitchell, Madeline C; Caspari, Oliver; Freeman Rosenzweig, Elizabeth S; Pallesen, Leif; Reeves, Gregory; Itakura, Alan; Roth, Robyn; Sommer, Frederik; Geimer, Stefan; Mühlhaus, Timo; Schroda, Michael; Goodenough, Ursula; Stitt, Mark; Griffiths, Howard; Jonikas, Martin C

    2016-05-24

    Biological carbon fixation is a key step in the global carbon cycle that regulates the atmosphere's composition while producing the food we eat and the fuels we burn. Approximately one-third of global carbon fixation occurs in an overlooked algal organelle called the pyrenoid. The pyrenoid contains the CO2-fixing enzyme Rubisco and enhances carbon fixation by supplying Rubisco with a high concentration of CO2 Since the discovery of the pyrenoid more that 130 y ago, the molecular structure and biogenesis of this ecologically fundamental organelle have remained enigmatic. Here we use the model green alga Chlamydomonas reinhardtii to discover that a low-complexity repeat protein, Essential Pyrenoid Component 1 (EPYC1), links Rubisco to form the pyrenoid. We find that EPYC1 is of comparable abundance to Rubisco and colocalizes with Rubisco throughout the pyrenoid. We show that EPYC1 is essential for normal pyrenoid size, number, morphology, Rubisco content, and efficient carbon fixation at low CO2 We explain the central role of EPYC1 in pyrenoid biogenesis by the finding that EPYC1 binds Rubisco to form the pyrenoid matrix. We propose two models in which EPYC1's four repeats could produce the observed lattice arrangement of Rubisco in the Chlamydomonas pyrenoid. Our results suggest a surprisingly simple molecular mechanism for how Rubisco can be packaged to form the pyrenoid matrix, potentially explaining how Rubisco packaging into a pyrenoid could have evolved across a broad range of photosynthetic eukaryotes through convergent evolution. In addition, our findings represent a key step toward engineering a pyrenoid into crops to enhance their carbon fixation efficiency. PMID:27166422

  20. A repeat protein links Rubisco to form the eukaryotic carbon-concentrating organelle

    PubMed Central

    Mackinder, Luke C. M.; Meyer, Moritz T.; Mettler-Altmann, Tabea; Chen, Vivian K.; Mitchell, Madeline C.; Caspari, Oliver; Freeman Rosenzweig, Elizabeth S.; Pallesen, Leif; Reeves, Gregory; Itakura, Alan; Roth, Robyn; Sommer, Frederik; Geimer, Stefan; Mühlhaus, Timo; Schroda, Michael; Goodenough, Ursula; Stitt, Mark; Griffiths, Howard; Jonikas, Martin C.

    2016-01-01

    Biological carbon fixation is a key step in the global carbon cycle that regulates the atmosphere's composition while producing the food we eat and the fuels we burn. Approximately one-third of global carbon fixation occurs in an overlooked algal organelle called the pyrenoid. The pyrenoid contains the CO2-fixing enzyme Rubisco and enhances carbon fixation by supplying Rubisco with a high concentration of CO2. Since the discovery of the pyrenoid more that 130 y ago, the molecular structure and biogenesis of this ecologically fundamental organelle have remained enigmatic. Here we use the model green alga Chlamydomonas reinhardtii to discover that a low-complexity repeat protein, Essential Pyrenoid Component 1 (EPYC1), links Rubisco to form the pyrenoid. We find that EPYC1 is of comparable abundance to Rubisco and colocalizes with Rubisco throughout the pyrenoid. We show that EPYC1 is essential for normal pyrenoid size, number, morphology, Rubisco content, and efficient carbon fixation at low CO2. We explain the central role of EPYC1 in pyrenoid biogenesis by the finding that EPYC1 binds Rubisco to form the pyrenoid matrix. We propose two models in which EPYC1’s four repeats could produce the observed lattice arrangement of Rubisco in the Chlamydomonas pyrenoid. Our results suggest a surprisingly simple molecular mechanism for how Rubisco can be packaged to form the pyrenoid matrix, potentially explaining how Rubisco packaging into a pyrenoid could have evolved across a broad range of photosynthetic eukaryotes through convergent evolution. In addition, our findings represent a key step toward engineering a pyrenoid into crops to enhance their carbon fixation efficiency. PMID:27166422

  1. Rubiscolytics: fate of Rubisco after its enzymatic function in a cell is terminated.

    PubMed

    Feller, Urs; Anders, Iwona; Mae, Tadahiko

    2008-01-01

    Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the predominant protein in photosynthesizing plant parts and the most abundant protein on earth. Amino acids deriving from its net degradation during senescence are transported to sinks (e.g. developing leaves, fruits). Rubisco catabolism is not controlled only by the overall sink demand. An accumulation of carbohydrates may also accelerate senescence and Rubisco degradation under certain conditions. Amino acids produced by proteolysis are rapidly redistributed in plants with proper source-sink relationships. In leaves of wheat plants with reduced sink capacity (e.g. sink removal, phloem interruption by steam girdling at the leaf base), Rubisco is degraded and free amino acids accumulate. They may be washed out in the rain during late senescence. In leaves of depodded soybeans, Rubisco is degraded and amino acids can be reutilized in these leaves for the synthesis of special vacuolar proteins in the paraveinal mesophyll (vegetative storage proteins). Nitrogen deriving from Rubisco degradation in older (senescing) leaves of annual crops is integrated to some extent again in newly synthesized Rubisco in younger leaves or photosynthesizing tissues of fruits. Finally, a high percentage of this nitrogen is accumulated in protein bodies (storage proteins). At the subcellular level, Rubisco can be degraded in intact chloroplasts. Reactive oxygen species may directly cleave the large subunit or modify it to become more susceptible to proteolysis. A metalloendopeptidase may play an important role in Rubisco degradation within intact chloroplasts. Additionally, the involvement of vacuolar endopeptidase(s) in Rubisco catabolism (at least under certain conditions) was postulated by various laboratories.

  2. Diversity and Expression of RubisCO Genes in a Perennially Ice-Covered Antarctic Lake during the Polar Night Transition

    PubMed Central

    Kong, Weidong; Ream, David C.; Priscu, John C.

    2012-01-01

    The autotrophic communities in the lakes of the McMurdo Dry Valleys, Antarctica, have generated interest since the early 1960s owing to low light transmission through the permanent ice covers, a strongly bimodal seasonal light cycle, constant cold water temperatures, and geographical isolation. Previous work has shown that autotrophic carbon fixation in these lakes provides an important source of organic matter to this polar desert. Lake Bonney has two lobes separated by a shallow sill and is one of several chemically stratified lakes in the dry valleys that support year-round biological activity. As part of an International Polar Year initiative, we monitored the diversity and abundance of major isoforms of RubisCO in Lake Bonney by using a combined sequencing and quantitative PCR approach during the transition from summer to polar winter. Form ID RubisCO genes related to a stramenopile, a haptophyte, and a cryptophyte were identified, while primers specific for form IA/B RubisCO detected a diverse autotrophic community of chlorophytes, cyanobacteria, and chemoautotrophic proteobacteria. Form ID RubisCO dominated phytoplankton communities in both lobes of the lake and closely matched depth profiles for photosynthesis and chlorophyll. Our results indicate a coupling between light availability, photosynthesis, and rbcL mRNA levels in deep phytoplankton populations. Regulatory control of rbcL in phytoplankton living in nutrient-deprived shallow depths does not appear to be solely light dependent. The distinct water chemistries of the east and west lobes have resulted in depth- and lobe-dependent variability in RubisCO diversity, which plays a role in transcriptional activity of the key gene responsible for carbon fixation. PMID:22492447

  3. Property Blocks: Games and Activities.

    ERIC Educational Resources Information Center

    Humphreys, Alan, Ed.; Dailey, Jean, Ed.

    This pamphlet describes the property blocks produced by MINNEMAST, and discusses their use in the development of thinking processes. Classification systems, including block diagrams and tree diagrams, are discussed. Sixteen classroom activities and eleven games which use the blocks are described. Suggestions to the teacher for further reading are…

  4. In Vivo Studies in Rhodospirillum rubrum Indicate That Ribulose-1,5-bisphosphate Carboxylase/Oxygenase (Rubisco) Catalyzes Two Obligatorily Required and Physiologically Significant Reactions for Distinct Carbon and Sulfur Metabolic Pathways.

    PubMed

    Dey, Swati; North, Justin A; Sriram, Jaya; Evans, Bradley S; Tabita, F Robert

    2015-12-25

    All organisms possess fundamental metabolic pathways to ensure that needed carbon and sulfur compounds are provided to the cell in the proper chemical form and oxidation state. For most organisms capable of using CO2 as sole source of carbon, ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco) catalyzes primary carbon dioxide assimilation. In addition, sulfur salvage pathways are necessary to ensure that key sulfur-containing compounds are both available and, where necessary, detoxified in the cell. Using knock-out mutations and metabolomics in the bacterium Rhodospirillum rubrum, we show here that Rubisco concurrently catalyzes key and essential reactions for seemingly unrelated but physiologically essential central carbon and sulfur salvage metabolic pathways of the cell. In this study, complementation and mutagenesis studies indicated that representatives of all known extant functional Rubisco forms found in nature are capable of simultaneously catalyzing reactions required for both CO2-dependent growth as well as growth using 5-methylthioadenosine as sole sulfur source under anaerobic photosynthetic conditions. Moreover, specific inactivation of the CO2 fixation reaction did not affect the ability of Rubisco to support anaerobic 5-methylthioadenosine metabolism, suggesting that the active site of Rubisco has evolved to ensure that this enzyme maintains both key functions. Thus, despite the coevolution of both functions, the active site of this protein may be differentially modified to affect only one of its key functions.

  5. Improving recombinant Rubisco biogenesis, plant photosynthesis and growth by coexpressing its ancillary RAF1 chaperone.

    PubMed

    Whitney, Spencer M; Birch, Rosemary; Kelso, Celine; Beck, Jennifer L; Kapralov, Maxim V

    2015-03-17

    Enabling improvements to crop yield and resource use by enhancing the catalysis of the photosynthetic CO2-fixing enzyme Rubisco has been a longstanding challenge. Efforts toward realization of this goal have been greatly assisted by advances in understanding the complexities of Rubisco's biogenesis in plastids and the development of tailored chloroplast transformation tools. Here we generate transplastomic tobacco genotypes expressing Arabidopsis Rubisco large subunits (AtL), both on their own (producing tob(AtL) plants) and with a cognate Rubisco accumulation factor 1 (AtRAF1) chaperone (producing tob(AtL-R1) plants) that has undergone parallel functional coevolution with AtL. We show AtRAF1 assembles as a dimer and is produced in tob(AtL-R1) and Arabidopsis leaves at 10-15 nmol AtRAF1 monomers per square meter. Consistent with a postchaperonin large (L)-subunit assembly role, the AtRAF1 facilitated two to threefold improvements in the amount and biogenesis rate of hybrid L8(A)S8(t) Rubisco [comprising AtL and tobacco small (S) subunits] in tob(AtL-R1) leaves compared with tob(AtL), despite >threefold lower steady-state Rubisco mRNA levels in tob(AtL-R1). Accompanying twofold increases in photosynthetic CO2-assimilation rate and plant growth were measured for tob(AtL-R1) lines. These findings highlight the importance of ancillary protein complementarity during Rubisco biogenesis in plastids, the possible constraints this has imposed on Rubisco adaptive evolution, and the likely need for such interaction specificity to be considered when optimizing recombinant Rubisco bioengineering in plants. PMID:25733857

  6. Effects of in vitro ozone treatment on proteolysis of purified rubisco from two hybrid poplar clones. [Populus maximowizii x trichocarpa

    SciTech Connect

    Landry, L.G.; Pell, E.J. )

    1989-04-01

    Plants exposed to ozone (O{sub 3}) exhibited symptoms of premature senescence, including early decline in quantity of rubisco. O{sub 3}-induced oxidation may cause changes in protein conformation of rubisco, resulting in enhanced proteolysis. To test this hypothesis, rubisco was purified from two hybrid clones of Populus maximowizii x trichocarpa, clones 388 and 245, and treated in vitro with O{sub 3} or air. Rubisco was then challenged with bromelain, papain, chymotrypsin, carboxypeptidase A, or endoproteinase Glu-C and percent degradation measured by SDS-PAGE and densitometric scanning of the gels. Degree of rubisco sensitivity to oxidation may be related to available sulfhydryl (SH) groups on the protein. The number of SH groups in native and denatured rubisco was measured for purified rubisco of both clones by DTNB titration method. The relationship between sensitivity to proteolysis and number and availability of SH groups is discussed.

  7. Prospects for improving CO2 fixation in C3-crops through understanding C4-Rubisco biogenesis and catalytic diversity.

    PubMed

    Sharwood, Robert E; Ghannoum, Oula; Whitney, Spencer M

    2016-06-01

    By operating a CO2 concentrating mechanism, C4-photosynthesis offers highly successful solutions to remedy the inefficiency of the CO2-fixing enzyme Rubisco. C4-plant Rubisco has characteristically evolved faster carboxylation rates with low CO2 affinity. Owing to high CO2 concentrations in bundle sheath chloroplasts, faster Rubisco enhances resource use efficiency in C4 plants by reducing the energy and carbon costs associated with photorespiration and lowering the nitrogen investment in Rubisco. Here, we show that C4-Rubisco from some NADP-ME species, such as maize, are also of potential benefit to C3-photosynthesis under current and future atmospheric CO2 pressures. Realizing this bioengineering endeavour necessitates improved understanding of the biogenesis requirements and catalytic variability of C4-Rubisco, as well as the development of transformation capabilities to engineer Rubisco in a wider variety of food and fibre crops. PMID:27131319

  8. Identification of Putative RuBisCo Activase (TaRca1)-The Catalytic Chaperone Regulating Carbon Assimilatory Pathway in Wheat (Triticum aestivum) under the Heat Stress.

    PubMed

    Kumar, Ranjeet R; Goswami, Suneha; Singh, Khushboo; Dubey, Kavita; Singh, Shweta; Sharma, Renu; Verma, Neeraj; Kala, Yugal K; Rai, Gyanendra K; Grover, Monendra; Mishra, Dwijesh C; Singh, Bhupinder; Pathak, Himanshu; Chinnusamy, Viswanathan; Rai, Anil; Praveen, Shelly

    2016-01-01

    RuBisCo activase (Rca) is a catalytic chaperone involved in modulating the activity of RuBisCo (key enzyme of photosynthetic pathway). Here, we identified eight novel transcripts from wheat through data mining predicted to be Rca and cloned a transcript of 1.4 kb from cv. HD2985, named as TaRca1 (GenBank acc. no. KC776912). Single copy number of TaRca1 was observed in wheat genome. Expression analysis in diverse wheat genotypes (HD2985, Halna, PBW621, and HD2329) showed very high relative expression of TaRca1 in Halna under control and HS-treated, as compared to other cultivars at different stages of growth. TaRca1 protein was predicted to be chloroplast-localized with numerous potential phosphorylation sites. Northern blot analysis showed maximum accumulation of TaRca1 transcript in thermotolerant cv. during mealy-ripe stage, as compared to thermosusceptible. Decrease in the photosynthetic parameters was observed in all the cultivars, except PBW621 in response to HS. We observed significant increase in the Rca activity in all the cultivars under HS at different stages of growth. HS causes decrease in the RuBisCo activity; maximum reduction was observed during pollination stage in thermosusceptible cvs. as validated through immunoblotting. We observed uniform carbon distribution in different tissues of thermotolerant cvs., as compared to thermosusceptible. Similarly, tolerance level of leaf was observed maximum in Halna having high Rca activity under HS. A positive correlation was observed between the transcript and activity of TaRca1 in HS-treated Halna. Similarly, TaRca1 enzyme showed positive correlation with the activity of RuBisCo. There is, however, need to manipulate the thermal stability of TaRca1 enzyme through protein engineering for sustaining the photosynthetic rate under HS-a novel approach toward development of "climate-smart" crop. PMID:27462325

  9. Identification of Two bZIP Transcription Factors Interacting with the Promoter of Soybean Rubisco Activase Gene (GmRCAα)

    PubMed Central

    Zhang, Jinyu; Du, Hongyang; Chao, Maoni; Yin, Zhitong; Yang, Hui; Li, Yakai; Huang, Fang; Yu, Deyue

    2016-01-01

    Rubisco activase (RCA), a key photosynthetic protein, catalyses the activation of Rubisco and thus plays an important role in photosynthesis. Although the RCA gene has been characterized in a variety of species, the molecular mechanism regulating its transcription remains unclear. Our previous studies on RCA gene expression in soybean suggested that expression of this gene is regulated by trans-acting factors. In the present study, we verified activity of the GmRCAα promoter in both soybean and Arabidopsis and used a yeast one-hybrid (Y1H) system for screening a leaf cDNA expression library to identify transcription factors (TFs) interacting with the GmRCAα promoter. Four basic leucine zipper (bZIP) TFs, GmbZIP04g, GmbZIP07g, GmbZIP1, and GmbZIP71, were isolated, and GmbZIP04g and GmbZIP07g were confirmed as able to bind to a 21-nt G-box-containing sequence. Additionally, the expression patterns of GmbZIP04g, GmbZIp07g, and GmRCAα were analyzed in response to abiotic stresses and during a 24-h period. Our study will help to advance elucidation of the network regulating GmRCAα transcription. PMID:27242832

  10. Arabidopsis thaliana ggt1 photorespiratory mutants maintain leaf carbon/nitrogen balance by reducing RuBisCO content and plant growth.

    PubMed

    Dellero, Younès; Lamothe-Sibold, Marlène; Jossier, Mathieu; Hodges, Michael

    2015-09-01

    Metabolic and physiological analyses of glutamate:glyoxylate aminotransferase 1 (GGT1) mutants were performed at the global leaf scale to elucidate the mechanisms involved in their photorespiratory growth phenotype. Air-grown ggt1 mutants showed retarded growth and development, that was not observed at high CO2 (3000 μL L(-1) ). When compared to wild-type (WT) plants, air-grown ggt1 plants exhibited glyoxylate accumulation, global changes in amino acid amounts including a decrease in serine content, lower organic acid levels, and modified ATP/ADP and NADP(+) /NADPH ratios. When compared to WT plants, their net CO2 assimilation rates (An ) were 50% lower and this mirrored decreases in ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) contents. High CO2 -grown ggt1 plants transferred to air revealed a rapid decrease of An and photosynthetic electron transfer rate while maintaining a high energetic state. Short-term (a night period and 4 h of light) transferred ggt1 leaves accumulated glyoxylate and exhibited low serine contents, while other amino acid levels were not modified. RuBisCO content, activity and activation state were not altered after a short-term transfer while the ATP/ADP ratio was lowered in ggt1 rosettes. However, plant growth and RuBisCO levels were both reduced in ggt1 leaves after a long-term (12 days) acclimation to air from high CO2 when compared to WT plants. The data are discussed with respect to a reduced photorespiratory carbon recycling in the mutants. It is proposed that the low An limits nitrogen-assimilation, this decreases leaf RuBisCO content until plants attain a new homeostatic state that maintains a constant C/N balance and leads to smaller, slower growing plants. PMID:26216646

  11. Arabidopsis thaliana ggt1 photorespiratory mutants maintain leaf carbon/nitrogen balance by reducing RuBisCO content and plant growth.

    PubMed

    Dellero, Younès; Lamothe-Sibold, Marlène; Jossier, Mathieu; Hodges, Michael

    2015-09-01

    Metabolic and physiological analyses of glutamate:glyoxylate aminotransferase 1 (GGT1) mutants were performed at the global leaf scale to elucidate the mechanisms involved in their photorespiratory growth phenotype. Air-grown ggt1 mutants showed retarded growth and development, that was not observed at high CO2 (3000 μL L(-1) ). When compared to wild-type (WT) plants, air-grown ggt1 plants exhibited glyoxylate accumulation, global changes in amino acid amounts including a decrease in serine content, lower organic acid levels, and modified ATP/ADP and NADP(+) /NADPH ratios. When compared to WT plants, their net CO2 assimilation rates (An ) were 50% lower and this mirrored decreases in ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) contents. High CO2 -grown ggt1 plants transferred to air revealed a rapid decrease of An and photosynthetic electron transfer rate while maintaining a high energetic state. Short-term (a night period and 4 h of light) transferred ggt1 leaves accumulated glyoxylate and exhibited low serine contents, while other amino acid levels were not modified. RuBisCO content, activity and activation state were not altered after a short-term transfer while the ATP/ADP ratio was lowered in ggt1 rosettes. However, plant growth and RuBisCO levels were both reduced in ggt1 leaves after a long-term (12 days) acclimation to air from high CO2 when compared to WT plants. The data are discussed with respect to a reduced photorespiratory carbon recycling in the mutants. It is proposed that the low An limits nitrogen-assimilation, this decreases leaf RuBisCO content until plants attain a new homeostatic state that maintains a constant C/N balance and leads to smaller, slower growing plants.

  12. Rubisco in marine symbiotic dinoflagellates: form II enzymes in eukaryotic oxygenic phototrophs encoded by a nuclear multigene family.

    PubMed

    Rowan, R; Whitney, S M; Fowler, A; Yellowlees, D

    1996-03-01

    Genes encoding ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) were cloned from dinoflagellate symbionts (Symbiodinium spp) of the giant clam Tridacna gigas and characterized. Strikingly, Symbiodinium Rubisco is completely different from other eukaryotic (form I) Rubiscos: it is a form II enzyme that is approximately 65% identical to Rubisco from Rhodospirillum rubrum (Rubisco forms I and II are approximately 25 to 30% identical); it is nuclear encoded by a multigene family; and the predominantly expressed Rubisco is encoded as a precursor polyprotein. One clone appears to contain a predominantly expressed Rubisco locus (rbcA), as determined by RNA gel blot analysis of Symbiodinium RNA and sequencing of purified Rubisco protein. Another contains an enigmatic locus (rbcG) that exhibits an unprecedented pattern of amino acid replacement but does not appear to be a pseudogene. The expression of rbcG has not been analyzed; it was detected only in the minor of two taxa of Symbiodinium that occur together in T. gigas. This study confirms and describes a previously unrecognized branch of Rubisco's evolution: a eukaryotic form II enzyme that participates in oxygenic photosynthesis and is encoded by a diverse, nuclear multigene family.

  13. Methane, oxygen, photosynthesis, rubisco and the regulation of the air through time.

    PubMed

    Nisbet, Euan G; Nisbet, R Ellen R

    2008-08-27

    Rubisco I's specificity, which today may be almost perfectly tuned to the task of cultivating the global garden, controlled the balance of carbon gases and O(2) in the Precambrian ocean and hence, by equilibration, in the air. Control of CO(2) and O(2) by rubisco I, coupled with CH(4) from methanogens, has for the past 2.9 Ga directed the global greenhouse warming, which maintains liquid oceans and sustains microbial ecology.Both rubisco compensation controls and the danger of greenhouse runaway (e.g. glaciation) put limits on biological productivity. Rubisco may sustain the air in either of two permissible stable states: either an anoxic system with greenhouse warming supported by both high methane mixing ratios as well as carbon dioxide, or an oxygen-rich system in which CO(2) largely fulfils the role of managing greenhouse gas, and in which methane is necessarily only a trace greenhouse gas, as is N(2)O. Transition from the anoxic to the oxic state risks glaciation. CO(2) build-up during a global snowball may be an essential precursor to a CO(2)-dominated greenhouse with high levels of atmospheric O(2). Photosynthetic and greenhouse-controlling competitions between marine algae, cyanobacteria, and terrestrial C3 and C4 plants may collectively set the CO(2) : O(2) ratio of the modern atmosphere (last few million years ago in a mainly glacial epoch), maximizing the productivity close to rubisco compensation and glacial limits.

  14. Methane, oxygen, photosynthesis, rubisco and the regulation of the air through time.

    PubMed

    Nisbet, Euan G; Nisbet, R Ellen R

    2008-08-27

    Rubisco I's specificity, which today may be almost perfectly tuned to the task of cultivating the global garden, controlled the balance of carbon gases and O(2) in the Precambrian ocean and hence, by equilibration, in the air. Control of CO(2) and O(2) by rubisco I, coupled with CH(4) from methanogens, has for the past 2.9 Ga directed the global greenhouse warming, which maintains liquid oceans and sustains microbial ecology.Both rubisco compensation controls and the danger of greenhouse runaway (e.g. glaciation) put limits on biological productivity. Rubisco may sustain the air in either of two permissible stable states: either an anoxic system with greenhouse warming supported by both high methane mixing ratios as well as carbon dioxide, or an oxygen-rich system in which CO(2) largely fulfils the role of managing greenhouse gas, and in which methane is necessarily only a trace greenhouse gas, as is N(2)O. Transition from the anoxic to the oxic state risks glaciation. CO(2) build-up during a global snowball may be an essential precursor to a CO(2)-dominated greenhouse with high levels of atmospheric O(2). Photosynthetic and greenhouse-controlling competitions between marine algae, cyanobacteria, and terrestrial C3 and C4 plants may collectively set the CO(2) : O(2) ratio of the modern atmosphere (last few million years ago in a mainly glacial epoch), maximizing the productivity close to rubisco compensation and glacial limits. PMID:18487133

  15. Rubisco without the Calvin cycle improves the carbon efficiency of developing green seeds.

    PubMed

    Schwender, Jörg; Goffman, Fernando; Ohlrogge, John B; Shachar-Hill, Yair

    2004-12-01

    Efficient storage of carbon in seeds is crucial to plant fitness and to agricultural productivity. Oil is a major reserve material in most seeds, and these oils provide the largest source of renewable reduced carbon chains available from nature. However, the conversion of carbohydrate to oil through glycolysis results in the loss of one-third of the carbon as CO2. Here we show that, in developing embryos of Brassica napus L. (oilseed rape), Rubisco (ribulose 1,5-bisphosphate carboxylase/oxygenase) acts without the Calvin cycle and in a previously undescribed metabolic context to increase the efficiency of carbon use during the formation of oil. In comparison with glycolysis, the metabolic conversion we describe provides 20% more acetyl-CoA for fatty-acid synthesis and results in 40% less loss of carbon as CO2. Our conclusions are based on measurements of mass balance, enzyme activity and stable isotope labelling, as well as an analysis of elementary flux modes.

  16. Temperature dependence of in vitro Rubisco kinetics in species of Flaveria with different photosynthetic mechanisms.

    PubMed

    Perdomo, Juan Alejandro; Cavanagh, Amanda P; Kubien, David S; Galmés, Jeroni

    2015-04-01

    There is general consensus in the literature that plants with different photosynthetic mechanisms (i.e. C3 vs. C4) have Rubiscos characterised by different kinetic performances. However, potential differences in the temperature dependencies of Rubisco kinetic parameters between C3 and C4 plants are uncertain. Accordingly, six species of Flaveria with contrasting photosynthetic mechanisms (C3, C3/C4 and C4) were selected and their Rubisco Michaelis-Menten constants for CO2 and RuBP (K c and K RuBP), carboxylase catalytic turnover rate ([Formula: see text]) and CO2/O2 specificity factor (S c/o) were measured between 10 and 40 °C. The results confirmed different Rubisco characteristics between C3 and C4 plants. Rubisco from the C3 species had higher E a for K c and [Formula: see text] than that from C4 species, which were translated into differences in the temperature response of the carboxylase catalytic efficiency ([Formula: see text]/K c). However, E a did not differ for S c/o or K RuBP. Although a mechanism remains uncertain, it appears that the Asp/Glu-149-Ala and Met-309-Ile substitutions lead to differences in the temperature responses of catalysis between C3 and C4 Rubiscos in Flaveria. Therefore, the above observations are consistent with the fact that C3 species have a higher photosynthetic efficiency and ecological dominance in cool environments, with respect to C4 species in temperate environments. PMID:25663529

  17. Structure and Identification of a Pterin Dehydratase-like Protein as a Ribulose-bisphosphate Carboxylase/Oxygenase (RuBisCO) Assembly Factor in the α-Carboxysome*

    PubMed Central

    Wheatley, Nicole M.; Sundberg, Christopher D.; Gidaniyan, Soheil D.; Cascio, Duilio; Yeates, Todd O.

    2014-01-01

    Carboxysomes are proteinaceous bacterial microcompartments that increase the efficiency of the rate-limiting step in carbon fixation by sequestering reaction substrates. Typically, α-carboxysomes are genetically encoded as a single operon expressing the structural proteins and the encapsulated enzymes of the microcompartment. In addition, depending on phylogeny, as many as 13 other genes are found to co-occur near or within α-carboxysome operons. One of these genes codes for a protein with distant homology to pterin-4α-carbinolamine dehydratase (PCD) enzymes. It is present in all α-carboxysome containing bacteria and has homologs in algae and higher plants. Canonical PCDs play an important role in amino acid hydroxylation, a reaction not associated with carbon fixation. We determined the crystal structure of an α-carboxysome PCD-like protein from the chemoautotrophic bacterium Thiomonas intermedia K12, at 1.3-Å resolution. The protein retains a three-dimensional fold similar to canonical PCDs, although the prominent active site cleft present in PCD enzymes is disrupted in the α-carboxysome PCD-like protein. Using a cell-based complementation assay, we tested the PCD-like proteins from T. intermedia and two additional bacteria, and found no evidence for PCD enzymatic activity. However, we discovered that heterologous co-expression of the PCD-like protein from Halothiobacillus neapolitanus with RuBisCO and GroELS in Escherichia coli increased the amount of soluble, assembled RuBisCO recovered from cell lysates compared with co-expression of RuBisCO with GroELS alone. We conclude that this conserved PCD-like protein, renamed here α-carboxysome RuBisCO assembly factor (or acRAF), is a novel RuBisCO chaperone integral to α-carboxysome function. PMID:24459150

  18. Effect of Nd{sup 3+} ion on carboxylation activity of ribulose-1,5-bisphosphate carboxylase/oxygenase of spinach

    SciTech Connect

    Liu Chao; Hong Fashui . E-mail: Hongfsh_cn@sina.com; Wu Kang; Ma, Hong-bing; Zhang Xueguang; Hong Chengjiao; Wu Cheng; Gao Fengqing; Yang Fan; Zheng Lei; Wang Xuefeng; Liu Tao; Xie Yaning; Xu Jianhua; Li Zhongrui

    2006-03-31

    Neodymium (Nd), as a member of rare earth elements, proved to enhance the photosynthesis rate and organic substance accumulation of spinach through the increase in carboxylation activity of Rubisco. Although the oxygenase activity of spinach Rubisco was slightly changed with the Nd{sup 3+} treatment, the specific factor of Rubisco was greatly increased. It was partially due to the promotion of Rubisco activase (R-A) activity but mainly to the formation of Rubisco-Rubisco activase super-complex, a heavier molecular mass protein (about 1200 kD) comprising both Rubisco and Rubisco activase. This super-complex was found during the extraction procedure of Rubisco by the gel electrophoresis and Western-blot studies. The formation of Rubisco-R-A super-complex suggested that the secondary structure of the protein purified from the Nd{sup 3+}-treated spinach was different from that of the control. Extended X-ray absorption fine structure study of the 'Rubisco' purified from the Nd{sup 3+}-treated spinach revealed that Nd was bound with four oxygen atoms and two sulfur atoms of amino acid residues at the Nd-O and Nd-S bond lengths of 2.46 and 2.89 A, respectively.

  19. Expression of a foreign Rubisco small subunit in tobacco with reduced levels of the native protein

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The cDNA, ArRbcS3, for the small subunit of Rubisco from Amaranthus retroflexus (pigweed) was expressed in tobacco (Nicotiana tabacum) under the control of a strong leaf-specific Lhcb promoter. The coding region of the ArRbcS3 was fused to the plastid targeting sequence of the native tobacco rbcS to...

  20. Structural and evolutionary relationships among RuBisCOs inferred from their large and small subunits.

    PubMed

    Xiang, Fu; Fang, Yuanping; Xiang, Jun

    2016-01-01

    Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is the key enzyme to assimilate CO(2) into the biosphere. The nonredundant structural data sets for three RuBisCO domain superfamilies, i.e. large subunit C-terminal domain (LSC), large subunit N-terminal domain (LSN) and small subunit domain (SS), were selected using QR factorization based on the structural alignment with QH as the similarity measure. The structural phylogenies were then constructed to investigate a possible functional significance of the evolutionary diversification. The LSC could have occurred in both bacteria and archaea, and has evolved towards increased complexity in both bacteria and eukaryotes with a 4-helix-2-helix-2-helix bundle being extended into a 5-helix-3-helix-3-helix one at the LSC carboxyl-terminus. The structural variations of LSN could have originated not only in bacteria with a short coil, but also in eukaryotes with a long one. Meanwhile, the SS dendrogram can be contributed to the structural variations at the βA-βB-loop region. All the structural variations observed in the coil regions have influence on catalytic performance or CO(2)/O(2) selectivities of RuBisCOs from different species. Such findings provide insights on RuBisCO improvements. PMID:27049618

  1. Isolated spinach ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit .sup..epsilon. N-methyltransferase and method of inactivating ribulose-1,5-bisphosphatase carboxylase/oxygenase large subunit .sup..epsilon. N-methyltransferase activity

    DOEpatents

    Houtz, Robert L.

    1999-01-01

    The gene sequence for ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) large subunit (LS) .sup..epsilon. N-methyltransferase (protein methylase III or Rubisco LSMT) from a plant which has a des(methyl) lysyl residue in the LS is disclosed. In addition, the full-length cDNA clones for Rubisco LSMT are disclosed. Transgenic plants and methods of producing same which have the Rubisco LSMT gene inserted into the DNA are also provided. Further, methods of inactivating the enzymatic activity of Rubisco LSMT are also disclosed.

  2. Isolated spinach ribulose-1,5-bisphosphate carboxylase/oxgenase large subunit .epsilon. n-methyltransferase and method of inactivating ribulose-1,5-bishosphatase .epsilon. n-methyltransferase activity

    DOEpatents

    Houtz, Robert L.

    2001-01-01

    The gene sequence for ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) large subunit (LS) .sup..epsilon. N-methyltansferase (protein methylase III or Rubisco LSMT) from a plant which has a des(methyl) lysyl residue in the LS is disclosed. In addition, the full-length cDNA clones for Rubisco LSMT are disclosed. Transgenic plants and methods of producing same which have the Rubisco LSMT gene inserted into the DNA are also provided. Further, methods of inactivating the enzymatic activity of Rubisco LSMT are also disclosed.

  3. The transport properties of activated carbon fibers

    SciTech Connect

    di Vittorio, S.L. . Dept. of Materials Science and Engineering); Dresselhaus, M.S. . Dept. of Electrical Engineering and Computer Science Massachusetts Inst. of Tech., Cambridge, MA . Dept. of Physics); Endo, M. . Dept. of Electrical Engineering); Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons. 19 refs., 4 figs.

  4. The Transport Properties of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    di Vittorio, S. L.; Dresselhaus, M. S.; Endo, M.; Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons.

  5. The impact of ozone on juvenile maize (Zea mays L.) plant photosynthesis: effects on vegetative biomass, pigmentation, and carboxylases (PEPc and Rubisco).

    PubMed

    Leitao, L; Bethenod, O; Biolley, J-P

    2007-07-01

    The impact of ozone on crops was more studied in C (3) than in C (4) species. In C (3) plants, ozone is known to induce a photosynthesis impairment that can result in significant depressions in biomass and crop yields. To investigate the impact of O (3) on C (4) plant species, maize seedlings ( ZEA MAYS L. cv. Chambord) were exposed to 5 atmospheres in open-top chambers: non-filtered air (NF, 48 nL L (-1) O (3)) and NF supplied with 20 (+ 20), 40 (+ 40), 60 (+ 60), and 80 (+ 80) nL L (-1) ozone. An unchambered plot was also available. Leaf area, vegetative biomass, and leaf dry mass per unit leaf area (LMA) were evaluated 33 days after seedling emergence in OTCs. At the same time, photosynthetic pigments as well as carboxylase (PEPc and Rubisco) activities and amounts were also examined in the 5th leaf. Ozone enhanced visible symptoms characterizing foliar senescence. Across NF, + 20, + 40, and + 60 atmospheres, both chlorophylls and carotenoids were found to be linearly decreased against increasing AOT40 ( CA. - 50 % in + 60). No supplementary decrease was observed between + 60 and + 80. Total above-ground biomass was reduced by 26 % in + 80 atmosphere; leaf dry matter being more depressed by ozone than leaf area. In some cases, LMA index was consistent to reflect low negative effects caused by a moderate increase in ozone concentration. PEPc and Rubisco were less sensitive to ozone than pigments: only the two highest external ozone doses reduced their activities by about 20 - 30 %. These changes might be connected to losses in PEPc and Rubisco proteins that were decreased by about one-third. The underlying mechanisms for these results were discussed with special reference to C (3) species. To conclude, we showed that both light and dark reactions of C (4) photosynthesis can be impaired by realistic ozone doses.

  6. Identification of Putative RuBisCo Activase (TaRca1)—The Catalytic Chaperone Regulating Carbon Assimilatory Pathway in Wheat (Triticum aestivum) under the Heat Stress

    PubMed Central

    Goswami, Suneha; Singh, Khushboo; Dubey, Kavita; Singh, Shweta; Sharma, Renu; Verma, Neeraj; Kala, Yugal K.; Rai, Gyanendra K.; Grover, Monendra; Mishra, Dwijesh C.; Singh, Bhupinder; Pathak, Himanshu; Chinnusamy, Viswanathan; Rai, Anil; Praveen, Shelly

    2016-01-01

    RuBisCo activase (Rca) is a catalytic chaperone involved in modulating the activity of RuBisCo (key enzyme of photosynthetic pathway). Here, we identified eight novel transcripts from wheat through data mining predicted to be Rca and cloned a transcript of 1.4 kb from cv. HD2985, named as TaRca1 (GenBank acc. no. KC776912). Single copy number of TaRca1 was observed in wheat genome. Expression analysis in diverse wheat genotypes (HD2985, Halna, PBW621, and HD2329) showed very high relative expression of TaRca1 in Halna under control and HS-treated, as compared to other cultivars at different stages of growth. TaRca1 protein was predicted to be chloroplast-localized with numerous potential phosphorylation sites. Northern blot analysis showed maximum accumulation of TaRca1 transcript in thermotolerant cv. during mealy-ripe stage, as compared to thermosusceptible. Decrease in the photosynthetic parameters was observed in all the cultivars, except PBW621 in response to HS. We observed significant increase in the Rca activity in all the cultivars under HS at different stages of growth. HS causes decrease in the RuBisCo activity; maximum reduction was observed during pollination stage in thermosusceptible cvs. as validated through immunoblotting. We observed uniform carbon distribution in different tissues of thermotolerant cvs., as compared to thermosusceptible. Similarly, tolerance level of leaf was observed maximum in Halna having high Rca activity under HS. A positive correlation was observed between the transcript and activity of TaRca1 in HS-treated Halna. Similarly, TaRca1 enzyme showed positive correlation with the activity of RuBisCo. There is, however, need to manipulate the thermal stability of TaRca1 enzyme through protein engineering for sustaining the photosynthetic rate under HS—a novel approach toward development of “climate-smart” crop. PMID:27462325

  7. Active Microwave Properties of Vegetation Canopies

    NASA Technical Reports Server (NTRS)

    Paris, J. F. (Principal Investigator)

    1985-01-01

    Potential users of radar imagery need a better fundamental understanding of the capabilities of radar systems for vegetation studies than past studies provide. One approach is the use of theoretical models to predict observable active microwave properties of vegetation. This in turn requires accurate observations of backscattering coefficients and other active microwave properties in field research studies. The background document for the SRAEC program emphasizes the need to relate electromagnetic parameters to classical biophysical descriptors and to understand the role of polarization, especially cross-polarization. The broad goal of this study is to increase the understanding of the effects of canopy structure on the active microwave properties of vegetation canopies, with particular attention to polarization.

  8. (Structure and expression of nuclear genes encoding rubisco activase)

    SciTech Connect

    Zielinski, R.E.

    1990-01-01

    Our activities during the past year have centered around two basic aspects of the project: describing more thoroughly the diurnal and light irradiance effects on activase gene expression in barley; and isolating and structurally characterizing cDNA and genomic DNA sequences encoding activase from barley. Three appendices are included that summarize these activities.

  9. Isotopic discrimination and kinetic parameters of RubisCO from the marine bloom-forming diatom, Skeletonema costatum.

    PubMed

    Boller, A J; Thomas, P J; Cavanaugh, C M; Scott, K M

    2015-01-01

    The cosmopolitan, bloom-forming diatom, Skeletonema costatum, is a prominent primary producer in coastal oceans, fixing CO2 with ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) that is phylogenetically distinct from terrestrial plant RubisCO. RubisCOs are subdivided into groups based on sequence similarity of their large subunits (IA-ID, II, and III). ID is present in several major oceanic primary producers, including diatoms such as S. costatum, coccolithophores, and some dinoflagellates, and differs substantially in amino acid sequence from the well-studied IB enzymes present in most cyanobacteria and in green algae and plants. Despite this sequence divergence, and differences in isotopic discrimination apparent in other RubisCO enzymes, stable carbon isotope compositions of diatoms and other marine phytoplankton are generally interpreted assuming enzymatic isotopic discrimination similar to spinach RubisCO (IB). To interpret phytoplankton δ(13) C values, S. costatum RubisCO was characterized via sequence analysis, and measurement of its KCO2 and Vmax , and degree of isotopic discrimination. The sequence of this enzyme placed it among other diatom ID RubisCOs. Michaelis-Menten parameters were similar to other ID enzymes (KCO2 = 48.9 ± 2.8 μm; Vmax = 165.1 ± 6.3 nmol min(-1 ) mg(-1) ). However, isotopic discrimination (ε = [(12) k/(13) k - 1] × 1000) was low (18.5‰; 17.0-19.9, 95% CI) when compared to IA and IB RubisCOs (22-29‰), though not as low as ID from coccolithophore, Emiliania huxleyi (11.1‰). Variability in ε-values among RubisCOs from primary producers is likely reflected in δ(13) C values of oceanic biomass. Currently, δ(13) C variability is ascribed to physical or chemical factors (e.g. illumination, nutrient availability) and physiological responses to these factors (e.g. carbon-concentrating mechanisms). Estimating the importance of these factors from δ(13) C measurements requires an accurate ε-value, and a mass

  10. Isotopic discrimination and kinetic parameters of RubisCO from the marine bloom-forming diatom, Skeletonema costatum.

    PubMed

    Boller, A J; Thomas, P J; Cavanaugh, C M; Scott, K M

    2015-01-01

    The cosmopolitan, bloom-forming diatom, Skeletonema costatum, is a prominent primary producer in coastal oceans, fixing CO2 with ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) that is phylogenetically distinct from terrestrial plant RubisCO. RubisCOs are subdivided into groups based on sequence similarity of their large subunits (IA-ID, II, and III). ID is present in several major oceanic primary producers, including diatoms such as S. costatum, coccolithophores, and some dinoflagellates, and differs substantially in amino acid sequence from the well-studied IB enzymes present in most cyanobacteria and in green algae and plants. Despite this sequence divergence, and differences in isotopic discrimination apparent in other RubisCO enzymes, stable carbon isotope compositions of diatoms and other marine phytoplankton are generally interpreted assuming enzymatic isotopic discrimination similar to spinach RubisCO (IB). To interpret phytoplankton δ(13) C values, S. costatum RubisCO was characterized via sequence analysis, and measurement of its KCO2 and Vmax , and degree of isotopic discrimination. The sequence of this enzyme placed it among other diatom ID RubisCOs. Michaelis-Menten parameters were similar to other ID enzymes (KCO2 = 48.9 ± 2.8 μm; Vmax = 165.1 ± 6.3 nmol min(-1 ) mg(-1) ). However, isotopic discrimination (ε = [(12) k/(13) k - 1] × 1000) was low (18.5‰; 17.0-19.9, 95% CI) when compared to IA and IB RubisCOs (22-29‰), though not as low as ID from coccolithophore, Emiliania huxleyi (11.1‰). Variability in ε-values among RubisCOs from primary producers is likely reflected in δ(13) C values of oceanic biomass. Currently, δ(13) C variability is ascribed to physical or chemical factors (e.g. illumination, nutrient availability) and physiological responses to these factors (e.g. carbon-concentrating mechanisms). Estimating the importance of these factors from δ(13) C measurements requires an accurate ε-value, and a mass

  11. Chloroplast EF-Tu and thermal aggregation of Rubisco activase

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chloroplast protein synthesis elongation factor, EF-Tu, has been implicated in heat tolerance in maize. The recombinant precursor of this protein, pre-EF-Tu, has been found to exhibit chaperone activity and protect heat-labile proteins, such as citrate synthase and malate dehydrogenase, from therma...

  12. An acidified thermostabilizing mini-peptide derived from the carboxyl extension of the larger isoform of the plant Rubisco activase.

    PubMed

    Zhang, Mengru; Li, Xujuan; Yang, Yumei; Luo, Zhu; Liu, Chang; Gong, Ming; Zou, Zhurong

    2015-10-20

    Thermostable fusion peptide partners are valuable in engineering thermostability in proteins. We evaluated the Arabidopsis counterpart (AtRAce) and an acidified derivative (mRAce) of the conserved carboxyl extension (RAce) of plant Rubisco activase (RCA) for their thermostabilizing properties in Escherichia coli and Saccharomyces cerevisiae using a protein fusion strategy. We used AtRAce and mRAce as fusion tails for the thermolabile protein RCA2 from Arabidopsis thaliana and Nicotiana tabacum. The homologous fusion of AtRAce with Arabidopsis RCA2 and the heterologous fusion of AtRAce with tobacco RCA2 increased the thermostability of both proteins. The acidified derivative mRAce conferred greater thermostability upon both proteins as compared with AtRAce. Moreover, mRAce enhanced the thermostability of other two thermolabile proteins from Jatropha curcas: the cytosolic ascorbate peroxidase 1 (JcAPX1) and the TATA-box binding protein isoform 1 (JcTBP1). We further report - for the first time - that JcTBP1 mediates heat tolerance in vivo in yeast. Thus, our study identifies a C-terminal acidic mini-peptide - the acidified derivative mRAce - with potential uses in improving the thermostability of heat-labile proteins and their associated heat tolerance in host organisms. PMID:26321073

  13. An acidified thermostabilizing mini-peptide derived from the carboxyl extension of the larger isoform of the plant Rubisco activase.

    PubMed

    Zhang, Mengru; Li, Xujuan; Yang, Yumei; Luo, Zhu; Liu, Chang; Gong, Ming; Zou, Zhurong

    2015-10-20

    Thermostable fusion peptide partners are valuable in engineering thermostability in proteins. We evaluated the Arabidopsis counterpart (AtRAce) and an acidified derivative (mRAce) of the conserved carboxyl extension (RAce) of plant Rubisco activase (RCA) for their thermostabilizing properties in Escherichia coli and Saccharomyces cerevisiae using a protein fusion strategy. We used AtRAce and mRAce as fusion tails for the thermolabile protein RCA2 from Arabidopsis thaliana and Nicotiana tabacum. The homologous fusion of AtRAce with Arabidopsis RCA2 and the heterologous fusion of AtRAce with tobacco RCA2 increased the thermostability of both proteins. The acidified derivative mRAce conferred greater thermostability upon both proteins as compared with AtRAce. Moreover, mRAce enhanced the thermostability of other two thermolabile proteins from Jatropha curcas: the cytosolic ascorbate peroxidase 1 (JcAPX1) and the TATA-box binding protein isoform 1 (JcTBP1). We further report - for the first time - that JcTBP1 mediates heat tolerance in vivo in yeast. Thus, our study identifies a C-terminal acidic mini-peptide - the acidified derivative mRAce - with potential uses in improving the thermostability of heat-labile proteins and their associated heat tolerance in host organisms.

  14. Detection of Rubisco and mycotoxins as potential contaminants of a plantibody against the hepatitis B surface antigen purified from tobacco.

    PubMed

    Geada, Déborah; Valdés, Rodolfo; Escobar, Arturo; Ares, Dulce M; Torres, Edel; Blanco, Reinaldo; Ferro, Williams; Dorta, Dayamí; González, Marcos; Alemán, María R; Padilla, Sigifredo; Gómez, Leonardo; Del Castillo, Norma; Mendoza, Otto; Urquiza, Dioslaida; Soria, Yordanka; Brito, José; Leyva, Alberto; Borroto, Carlos; Gavilondo, Jorge V

    2007-10-01

    Antibodies have been one of the proteins widely expressed in tobacco plants for pharmaceutical purposes, which demand contaminant free preparations. Rubisco constitutes 40-60% of tobacco leaf soluble proteins; therefore it is the major potential protein contaminant of plantibodies, while mycotoxins are toxic compounds that could be introduced during the biomass production and post-harvest stages with important consequences to human health. The objective of this paper was to investigate whether Rubisco and mycotoxins are present in Plantibody HB-01 preparations used in the immunopurification of the hepatitis B surface antigen. Rubisco was purified from Nicotiana tabacum yielding 154 microg of protein per gram of leaves and purity over 95%. Among mouse monoclonal antibodies generated against this enzyme, the CBSS.Rub-2 was selected for its immunodetection. It recognizes a conserved sequential epitope of Rubisco large subunit with an affinity constant of 0.13 x 10(8)M(-1). Rubisco quantification limit was 1 microg spreading to the measurement of this contaminant less than 4% of plantibodies samples. Additionally, according to a Reverse Phase-HPLC used to measure the level of adventitiously introduced contaminants, it can be concluded that aflatoxins B1, B2, G1 and G2 were undetected in the purified Plantibody HB-01 samples.

  15. Metabolic indicators of drought stress tolerance in wheat: glutamine synthetase isoenzymes and Rubisco.

    PubMed

    Nagy, Zoltán; Németh, Edit; Guóth, Adrienn; Bona, Lajos; Wodala, Barnabás; Pécsváradi, Attila

    2013-06-01

    Drought stress has a considerable impact on the ecosystem and agriculture. Continuous water deficit induces early leaf senescence in plants. During this process, chloroplasts are degraded and photosynthesis drastically drops. The objective of this investigation was to look into the regulation of nitrogen and carbon metabolism during water deficit. Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase; EC 4.1.1.39) and the total protein contents inform us of the sink-source relation in plants. Glutamine synthetase (GS, EC 6.3.1.2) isoenzymes are good markers of plastid status (GS2) and the nitrogen metabolism (GS1). Tolerant and sensitive wheat (Triticum aestivum L.) genotypes were tested, which are widely used in agriculture. The amount of protein, Rubisco and GS isoforms in leaves were measured during the grain filling period, as indicative traits that ultimately determine the onset and stage of senescence. The symptoms of senescence first appeared on the oldest and finally on the youngest leaves. Drought stress disrupted the sequentiality of senescence in the sensitive varieties. An untimely senescence appeared in flag leaves, earlier than in the older leaves. Total protein and Rubisco contents decreased and the GS2 isoenzyme declined considerably in the youngest leaves. In the tolerant varieties, however, these physiological parameters did not change under drought, only the sequential senescence of leaf levels accelerated in some cases compared to the control, well-watered plants. Our results revealed that GS is a good indicator of drought stress, which can be applied for the characterization of wheat cultivars in terms of drought stress tolerance.

  16. Modelling ¹⁸O₂ and ¹⁶O₂ unidirectional fluxes in plants: II. analysis of rubisco evolution.

    PubMed

    André, Marcel J

    2011-02-01

    The studies of Rubisco characteristics observed during plant evolution show that the variation of the Rubisco specificity factor only improved by two times from cyanobacteria to modern C3 plants. However we note important variations of the ratio between the maximum rates of oxygenation and carboxylation (V(O)/V(C)). Modelling in vivo ¹⁸O₂ data in plant gas exchange shows that the oxygenation reaction of Rubisco plays a regulating role when the photochemical energy exceeds the carboxylation capacity. A protective index 'oxygenation capacity' is postulated, related to the ratio V(O)/V(C) of Rubisco, and hence to the sink energy effect of photorespiration. Analysing the trends of Rubisco parameters along the evolutionary scale, we show: (1) the increase of both V(C) and V(O); (2) the enhancement of CO₂ affinity; and (3) the rise in oxygenation capacity at the expense of the CO₂ specificity. Hence, the factors of evolutionary pressure have not only directed the enzyme towards a more efficient utilisation of CO₂, but mainly to positively use the unavoidable great loss of energy and assimilated carbon in the process of photorespiration. These observations reinforce the hypothesis of plant-atmosphere co-evolution and of the complex role of Rubisco, which seems to be selected to develop both better CO₂ affinity and oxygenation capacity. The latter increases the capacity of sink of photorespiration, in particular, during water stress or under high irradiance, the two conditions experienced by plants in terrestrial environments. These observations help to explain some handicaps of C4 plants, and the supremacy of CAM and C3 perennial higher plants in arid environments.

  17. Effect of ozone on degradation and mRNA levels of Rubisco in relation to potato leaf age

    SciTech Connect

    Eckardt, N.A.; Pell, E.J. )

    1993-05-01

    Leaf senescence is characterized by loss of the major photosynthetic enzyme, Ribulose bisphosphate carboxylase (Rubisco). Exposure to ozone (O[sub 3]) is often associated with a premature decline in the quantity of this enzyme. Declines in Rubisco quantity could arise through inhibition of synthesis or enhancement of degradation. Several experiments were conducted to investigate the effect of O[sub 3] on these events in immature and mature leaves of potato. The effect of O[sub 3] on Rubisco synthesis was investigated indirectly by measuring the relative quantities of mRNA for the rubisco large (rbcL) and small (rbcS) subunits following a 5 hour exposure to 0.309 [mu]L L[sup [minus]1] O[sup 3] or charcoal-filtered air. O[sup 3] treatment was associated with a significant loss in rbcS mRNA in immature and mature potato leaves sampled immediately following the exposure. After the O[sup 3] exposure, a set of plants was placed in the dark at 30 C for two days. Levels of rbcS mRNA declined rapidly during the first twelve hours of dark incubation, thus declines in Rubisco quantity following two days of dark incubation were ascribed to degradation. Enhanced degradation due to O[sub 3] during the dark incubation was observed in the mature leaves, but not in the immature leaves. We conclude that O[sub 3] can cause both inhibited synthesis and enhanced degradation of Rubisco, and the response in dependent on leaf age.

  18. Rubisco expression in the dinoflagellate Symbiodinium sp. is influenced by both photoperiod and endosymbiotic lifestyle.

    PubMed

    Mayfield, Anderson B; Hsiao, Yi-Yuong; Chen, Hung-Kai; Chen, Chii-Shiarng

    2014-08-01

    Although the importance of anthozoan-dinoflagellate (genus Symbiodinium) endosymbioses in the establishment of coral reef ecosystems is evident, little is known about the molecular regulation of photosynthesis in the intra-gastrodermal symbiont communities, particularly with respect to the rate-limiting Calvin cycle enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). In this study, we analyzed rubisco mRNA (rbcL) and protein (RBCL) concentrations over the diel cycle in both cultured and endosymbiotic Symbiodinium samples. In the former, rbcL expression increased upon illumination and decreased during the dark, a pattern that was upheld under continual dark incubation. A different trend in rbcL expression was observed in endosymbiotic Symbiodinium residing within sea anemone (Aiptasia pulchella) tissues, in which illumination gradually led to decreased rbcL mRNA expression. Unexpectedly, RBCL protein expression did not vary over time within anemone tissues, and in neither cultured nor endosymbiotic samples was a correlation between gene and protein expression documented. It appears, then, that photoperiod, lifestyle, and posttranscriptional regulation are all important drivers of RBCL expression in this ecologically important dinoflagellate. PMID:24449387

  19. Rubisco expression in the dinoflagellate Symbiodinium sp. is influenced by both photoperiod and endosymbiotic lifestyle.

    PubMed

    Mayfield, Anderson B; Hsiao, Yi-Yuong; Chen, Hung-Kai; Chen, Chii-Shiarng

    2014-08-01

    Although the importance of anthozoan-dinoflagellate (genus Symbiodinium) endosymbioses in the establishment of coral reef ecosystems is evident, little is known about the molecular regulation of photosynthesis in the intra-gastrodermal symbiont communities, particularly with respect to the rate-limiting Calvin cycle enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). In this study, we analyzed rubisco mRNA (rbcL) and protein (RBCL) concentrations over the diel cycle in both cultured and endosymbiotic Symbiodinium samples. In the former, rbcL expression increased upon illumination and decreased during the dark, a pattern that was upheld under continual dark incubation. A different trend in rbcL expression was observed in endosymbiotic Symbiodinium residing within sea anemone (Aiptasia pulchella) tissues, in which illumination gradually led to decreased rbcL mRNA expression. Unexpectedly, RBCL protein expression did not vary over time within anemone tissues, and in neither cultured nor endosymbiotic samples was a correlation between gene and protein expression documented. It appears, then, that photoperiod, lifestyle, and posttranscriptional regulation are all important drivers of RBCL expression in this ecologically important dinoflagellate.

  20. RuBisCO in Non-Photosynthetic Alga Euglena longa: Divergent Features, Transcriptomic Analysis and Regulation of Complex Formation.

    PubMed

    Záhonová, Kristína; Füssy, Zoltán; Oborník, Miroslav; Eliáš, Marek; Yurchenko, Vyacheslav

    2016-01-01

    Euglena longa, a close relative of the photosynthetic model alga Euglena gracilis, possesses an enigmatic non-photosynthetic plastid. Its genome has retained a gene for the large subunit of the enzyme RuBisCO (rbcL). Here we provide new data illuminating the putative role of RuBisCO in E. longa. We demonstrated that the E. longa RBCL protein sequence is extremely divergent compared to its homologs from the photosynthetic relatives, suggesting a possible functional shift upon the loss of photosynthesis. Similarly to E. gracilis, E. longa harbors a nuclear gene encoding the small subunit of RuBisCO (RBCS) as a precursor polyprotein comprising multiple RBCS repeats, but one of them is highly divergent. Both RBCL and the RBCS proteins are synthesized in E. longa, but their abundance is very low compared to E. gracilis. No RBCS monomers could be detected in E. longa, suggesting that processing of the precursor polyprotein is inefficient in this species. The abundance of RBCS is regulated post-transcriptionally. Indeed, blocking the cytoplasmic translation by cycloheximide has no immediate effect on the RBCS stability in photosynthetically grown E. gracilis, but in E. longa, the protein is rapidly degraded. Altogether, our results revealed signatures of evolutionary degradation (becoming defunct) of RuBisCO in E. longa and suggest that its biological role in this species may be rather unorthodox, if any. PMID:27391690

  1. RuBisCO in Non-Photosynthetic Alga Euglena longa: Divergent Features, Transcriptomic Analysis and Regulation of Complex Formation

    PubMed Central

    Záhonová, Kristína; Füssy, Zoltán; Oborník, Miroslav; Eliáš, Marek

    2016-01-01

    Euglena longa, a close relative of the photosynthetic model alga Euglena gracilis, possesses an enigmatic non-photosynthetic plastid. Its genome has retained a gene for the large subunit of the enzyme RuBisCO (rbcL). Here we provide new data illuminating the putative role of RuBisCO in E. longa. We demonstrated that the E. longa RBCL protein sequence is extremely divergent compared to its homologs from the photosynthetic relatives, suggesting a possible functional shift upon the loss of photosynthesis. Similarly to E. gracilis, E. longa harbors a nuclear gene encoding the small subunit of RuBisCO (RBCS) as a precursor polyprotein comprising multiple RBCS repeats, but one of them is highly divergent. Both RBCL and the RBCS proteins are synthesized in E. longa, but their abundance is very low compared to E. gracilis. No RBCS monomers could be detected in E. longa, suggesting that processing of the precursor polyprotein is inefficient in this species. The abundance of RBCS is regulated post-transcriptionally. Indeed, blocking the cytoplasmic translation by cycloheximide has no immediate effect on the RBCS stability in photosynthetically grown E. gracilis, but in E. longa, the protein is rapidly degraded. Altogether, our results revealed signatures of evolutionary degradation (becoming defunct) of RuBisCO in E. longa and suggest that its biological role in this species may be rather unorthodox, if any. PMID:27391690

  2. Isolation and characterization of rubisco small subunit gene promoter from common wheat (Triticum aestivum L.).

    PubMed

    Mukherjee, Shalini; Stasolla, Claudio; Brûlé-Babel, Anita; Ayele, Belay T

    2015-01-01

    Choice of an appropriate promoter is critical to express target genes in intended tissues and developmental stages. However, promoters capable of directing gene expression in specific tissues and stages are not well characterized in monocot species. To identify such a promoter in wheat, this study isolated a partial sequence of the wheat small subunit of RuBisCO (TarbcS) promoter. In silico analysis revealed the presence of elements that are characteristic to rbcS promoters of other, mainly dicot, species. Transient expression of the TarbcS:GUS in immature wheat embryos and tobacco leaves but not in the wheat roots indicate the functionality of the TarbcS promoter fragment in directing the expression of target genes in green plant tissues.

  3. Metabolome analysis of photosynthesis and the related primary metabolites in the leaves of transgenic rice plants with increased or decreased Rubisco content.

    PubMed

    Suzuki, Yuji; Fujimori, Tamaki; Kanno, Keiichi; Sasaki, Atsushi; Ohashi, Yoshiaki; Makino, Amane

    2012-08-01

    Because the comprehensive effects on metabolism by genetic manipulation of leaf Rubisco content are unknown, metabolome analysis was carried out on transgenic rice plants with increased or decreased Rubisco content using the capillary electrophoresis-time-of-flight mass spectrometry (CE-TOFMS) technique. In RBCS-sense plants, an increase in Rubisco content did not improve light-saturated photosynthesis. Glyceraldehyde 3-phosphate and sedoheputulose 7-phosphate levels increased, but ribulose bisphosphate (RuBP), ATP and ADP levels were not affected. It is considered from these results that RuBP regeneration independent of ATP supply became a bottleneck for photosynthesis. In RBCS-antisense plants, a decline in Rubisco content decreased photosynthesis with a substantial accumulation of RuBP. ATP and ADP levels also increased and were associated with increases in the diphosphate and triphosphate compounds of other nucleosides. These results imply that a decline in Rubisco content slowed down the Calvin cycle and that the resultant excess energy of ATP was transferred to other nucleoside diphosphates and triphosphates. The levels of amino acids tended to decline in RBCS-sense plants and increase in RBCS-antisense plants, probably reflecting the demand for Rubisco synthesis. Starch and carbohydrate levels decreased only in RBCS-antisense plants. Thus, genetic manipulation of Rubisco contents widely affected C and N metabolism in rice.

  4. Functional analysis of the rice rubisco activase promoter in transgenic Arabidopsis

    SciTech Connect

    Yang, Zhipan; Lu, Qingtao; Wen, Xiaogang; Chen, Fan; Lu, Congming

    2012-02-17

    Highlights: Black-Right-Pointing-Pointer Rice rubisco activase promoter was analyzed in transgenic Arabidopsis system. Black-Right-Pointing-Pointer Region conferring tissue specific and light inducible expression of Rca was identified. Black-Right-Pointing-Pointer -58 to +43 bp region mediates tissue-specific expression of rice Rca. Black-Right-Pointing-Pointer Light inducible expression of rice Rca is mediated by -297 to -58 bp region. Black-Right-Pointing-Pointer Rice nuclear proteins bind specifically with the light inducible region. -- Abstract: To gain a better understanding of the regulatory mechanism of the rice rubisco activase (Rca) gene, variants of the Rca gene promoter (one full-length and four deletion mutants) fused to the coding region of the bacterial reporter gene {beta}-glucuronidase (GUS) were introduced into Arabidopsis via Agrobacterium-mediated transformation. Our results show that a 340 bp fragment spanning from -297 to +43 bp relative to the transcription initiation site is enough to promote tissue-specific and light-inducible expression of the rice Rca gene as done by the full-length promoter (-1428 to +43 bp). Further deletion analysis indicated that the region conferring tissue-specificity of Rca expression is localized within a 105 bp fragment from -58 to +43 bp, while light-inducible expression of Rca is mediated by the region from -297 to -58 bp. Gel shift assays and competition experiments demonstrated that rice nuclear proteins bind specifically with the fragment conferring light responsiveness at more than one binding site. This implies that multiple cis-elements may be involved in light-induced expression of the rice Rca gene. These works provide a useful reference for understanding transcriptional regulation mechanism of the rice Rca gene, and lay a strong foundation for further detection of related cis-elements and trans-factors.

  5. [Oregano: properties, composition and biological activity].

    PubMed

    Arcila-Lozano, Cynthia Cristina; Loarca-Piña, Guadalupe; Lecona-Uribe, Salvador; González de Mejía, Elvira

    2004-03-01

    The oregano spice includes various plant species. The most common are the genus Origanum, native of Europe, and the Lippia, native of Mexico. Among the species of Origanum. their most important components are the limonene, gamma-cariofilene, rho-cymenene, canfor, linalol, alpha-pinene, carvacrol and thymol. In the genus Lippia, the same compounds can be found. The oregano composition depends on the specie, climate, altitude, time of recollection and the stage of growth. Some of the properties of this plant's extracts are being currently studied due to the growing interest for substituting synthetic additives commonly found in foods. Oregano has a good antioxidant capacity and also presents antimicrobial activity against pathogenic microorganisms like Salmonella typhimurium, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, among others. These are all characteristics of interest for the food industry because they may enhance the safety and stability of foods. There are also some reports regarding the antimutagenic and anticarcinogenic effect of oregano; representing an alternative for the potential treatment and/or prevention of certain chronic ailments, like cancer. PMID:15332363

  6. Was photosynthetic RuBisCO recruited by acquisitive evolution from RuBisCO-like proteins involved in sulfur metabolism?

    PubMed

    Ashida, Hiroki; Danchin, Antoine; Yokota, Akiho

    2005-01-01

    Genome analyses have revealed that the genomes of non-photosynthetic bacteria including Bacillus subtilis code for proteins similar to the large subunit of RuBisCO (called RuBisCO-like protein (RLP)). This raises a fundamental question as to their functional relationship to photosynthetic RuBisCO. Recently, we identified the RLP of B. subtilis as the 2,3-diketo-5-methylthiopentyl-1-phosphate enolase in the methionine salvage pathway. In this mini-review, we suggest functional and evolutionary links between B. subtilis RLP and photosynthetic RuBisCO. Furthermore, we propose that photosynthetic RuBisCOs evolved from RLPs similar to that found in B. subtilis.

  7. Variability in Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Small Subunits and Carboxylation Activity in Fern Gametophytes Grown under Different Light Spectra 1

    PubMed Central

    Eilenberg, Haviva; Beer, Sven; Gepstein, Shimon; Geva, Nurit; Tadmor, Orly; Zilberstein, Aviah

    1991-01-01

    Two distinct ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) small subunit (SSU) populations were observed in Pteris vittata gametophytes grown under different illumination conditions. Exposure of the fern gametophytes to continuous red light (R) resulted in Rubisco SSUs that were not recognized by polyclonal antibodies raised against SSUs from spinach. Unlike the R-induced SSUs, blue light (B) induced SSUs were well recognized. This difference in SSU composition also reflected in Rubisco activity. In vitro, B-induced Rubisco exhibits a significantly higher carboxylation activity as compared to the R-induced Rubisco. Approximately a two- to threefold increase in the Vmax value of the B-induced carboxylase as compared to the R-induced one was measured. It thus seems very likely that certain domains in the SSU molecule affect enzyme activity. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:16667969

  8. The crystal structure of rubisco from Alcaligenes eutrophus reveals a novel central eight-stranded beta-barrel formed by beta-strands from four subunits.

    PubMed

    Hansen, S; Vollan, V B; Hough, E; Andersen, K

    1999-05-14

    Ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) is involved in photosynthesis where it catalyzes the initial step in the fixation of carbon dioxide. The enzyme also catalyzes a competing oxygenation reaction leading to loss of fixed carbon dioxide, thus reducing the net efficiency of photosynthesis significantly. Rubisco has therefore been studied extensively, and a challenging goal is the engineering of a more photosynthetically efficient enzyme. Hexadecameric rubiscos fall in two distinct groups, "green-like" and "red-like". The ability to discriminate between CO2 and O2 as substrates varies significantly, and some algae have red-like rubisco with even higher specificity for CO2 than the plant enzyme. The structure of unactivated rubisco from Alcaligenes eutrophus has been determined to 2.7 A resolution by molecular replacement and refined to R and Rfree values of 26.6 and 32.2 %, respectively. The overall fold of the protein is very similar to the rubisco structures solved previously for green-like hexadecameric enzymes, except for the extended C-terminal domains of the small subunits which together form an eight-stranded beta-barrel which sits as a plug in the entrance to the central solvent channel in the molecule. The present structure is the first which has been solved for a red-like rubisco and is likely to represent a fold which is common for this group. The small subunits in general are believed to have a stabilizing effect, and the new quaternary structure in the oligomer of the present structure is likely to contribute even more to this stabilization of the assembled rubisco protein. PMID:10329167

  9. Whole-plant growth and N utilization in transgenic rice plants with increased or decreased Rubisco content under different CO2 partial pressures.

    PubMed

    Sudo, Emi; Suzuki, Yuji; Makino, Amane

    2014-11-01

    Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) strongly limits photosynthesis at lower CO2 concentration [CO2] whereas [corrected] Rubisco limitation is cancelled by elevated [CO2]. Therefore, increase or reduction in Rubisco content by transformation with a sense or an antisense RBCS construct are expected to alter the biomass production under different CO2 levels. RBCS-sense (125% Rubisco of wild-type) and -antisense (35% Rubisco of wild-type) rice (Oryza sativa L.) plants were grown for 63 days at three different CO2 levels: low [CO2] (28 Pa), normal [CO2] (40 Pa) and elevated [CO2] (120 Pa). The biomass of RBCS-sense plants was 32% and 15% greater at low [CO2] and normal [CO2] than that of the wild-type plants, respectively, but did not differ at elevated [CO2]. Conversely, the biomass of RBCS-antisense plants was the smallest at low [CO2]. Thus, overproduction of Rubisco was effective for biomass production at low [CO2]. Greater biomass production at low [CO2] in RBCS-sense plants was caused by an increase in the net assimilation rate, and associated with an increase in the amount of N uptake. Furthermore, Rubisco overproduction in RBCS-sense plants was also promoted at low [CO2]. Although it seems that low [CO2]-growth additionally stimulates the effect of RBCS overexpression, such a phenomenon observed at low [CO2] was mediated through an increase in total leaf N content. Thus, the dependence of the growth improvement in RBCS-sense rice on growth [CO2] was closely related to the degree of Rubisco overproduction which was accompanied not only by leaf N content but also by whole plant N content.

  10. Interaction between potyvirus P3 and ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) of host plants.

    PubMed

    Lin, Lin; Luo, Zhaopeng; Yan, Fei; Lu, Yuwen; Zheng, Hongying; Chen, Jianping

    2011-08-01

    The P3 protein encoded by Shallot yellow stripe virus onion isolate (SYSV-O) interacted in the Yeast Two-hybrid (Y2H) system and in co-immunoprecipitation (Co-IP) assays with the large subunit of the ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) protein that is encoded by the rbcL gene of its onion host. Dissection analysis by Y2H showed that the main part of SYSV P3 (amino acids 1-390) and onion RbcL (amino acids 1-137) were responsible for the interaction. The P3 proteins encoded by Onion yellow dwarf virus (OYDV), Soybean mosaic virus Pinellia isolate (SMV-P), and Turnip mosaic virus (TuMV) also interacted with RbcL, suggesting that a P3/RbcL interaction might exist generally for potyviruses. An interaction between P3 of these potyviruses and the small subunit of RubisCO (RbcS) was also demonstrated. Moreover, the P3N-PIPO protein encoded by a newly identified open reading frame embedded within the P3 cistron also interacted with both RbcL and RbcS. It is possible that the potyvirus P3 protein affects the normal functions of RubisCO which thus contributes to symptom development. PMID:21400205

  11. Amplification of ribulose biphosphate carboxylase/oxygenase large subunit (RuBisCO LSU) gene fragments from Thiobacillus ferrooxidans and a moderate thermophile using polymerase chain reaction.

    PubMed

    Holden, P J; Brown, R W

    1993-07-01

    Southern blot analysis of DNA from an iron-oxidising moderate thermophile NMW-6 and from Thiobacillus ferrooxidans strain TFI-35 demonstrated sequences homologous to the RuBisCO LSU gene of Synechococcus. DNA fragments (457 bp) encoding part of the RuBisCO LSU gene (amino acids 73-200) were amplified from the genomic DNA of Thiobacillus ferrooxidans and the moderate thermophile NMW-6 using the polymerase chain reaction (PCR) technique (Saiki et al. (1985) Science 233, 1350-1354). A comparison with the LSU sequences from T. ferrooxidans, Alcaligenes eutrophus, Chromatium vinosum, Synechococcus and Spinacea oleracea, which all have RuBisCOs with a hexadecameric structure, showed that the RuBisCO LSU gene sequence from NMW-6 appeared to be most closely related to that of the hydrogen bacterium A. eutrophus which showed 71.9% homology at the amino acid level. Despite its physiological similarity, T. ferrooxidans showed only 64.1% homology to the amino acid sequence from NMW-6 and had the lowest DNA homology (60.9%) of the hexadecameric type RuBisCOs. In the region sequenced, T. ferrooxidans and the RuBisCOs of the phototrophs C. vinosum, Synechococcus and S. oleracea, had 17 residues that were completely conserved which were substituted in both NMW-6 and A. eutrophus, 11 of these being identical substitutions. Comparison of the nucleotide and derived amino acid sequences of the RuBisCO LSU fragment from T. ferrooxidans with other RuBisCO sequences indicated a closer relationship to the hexadecameric type LSU genes of photosynthetic origin than to that of A. eutrophus. The T. ferrooxidans amino acid sequence showed 93.8%, 78.9% and 77.3% homology, respectively, to the C. vinosum, Synechococcus and S. oleracea (spinach) sequences but only 56.2% to A. eutrophus. The DNA sequence from Rhodospirillum rubrum, which has the atypical large subunit dimer RuBisCO structure with no small subunit, showed 39.2% and 42.7% homology, respectively, with the sequences of NMW-6 and T

  12. Spectroscopic properties of pharmacologically active phenols

    NASA Astrophysics Data System (ADS)

    Tolstorozhev, G. B.; Skornyakov, I. V.; Bel'kov, M. V.; Shadyro, O. I.; Polozov, G. I.; Sorokin, V. L.; Ksendzova, G. A.

    2012-05-01

    The IR Fourier-transform spectra of pharmacologically active phenol molecules in solutions in CCl4 and in the crystalline state have been studied. Phenol derivatives with different directivities and different levels of pharmacological efficiency have been examined. Based on analysis of the IR spectra of screened phenols, the antimicrobial activity of phenols with free hydroxyl groups has been shown to be highest. The high antimicrobial activity of aminophenols is related to the formation of intramolecular hydrogen bonds. For aminophenols that are active against herpesviruses, O-H...N hydrogen bonds are formed in molecules. The main characteristic of the high antiviral activity against A-type influenza is predominance of intramolecular hydrogen bonds of the O-H...O=C type in molecules. Sulfur-containing aminophenols, which manifest activity against HIV infection, are characterized by the occurrence of hydrogen bonds that involve the participation of the OH, NH, and SO2 groups.

  13. SOME CHEMICAL PROPERTIES UNDERLYING ARSENIC'S BIOLOGICAL ACTIVITY

    EPA Science Inventory

    ABSTRACT

    In this paper some of the chemical properties of arsenicals (atomic
    and molecular orbitals, electronegativity, valence state, changes between
    valence state, nucleophilicity, the hard/soft acid/base principle) that may
    account for some of the b...

  14. Emergent properties in experiments with active microparticles

    NASA Astrophysics Data System (ADS)

    Palacci, Jeremie

    Self-propelled micro-particles are intrinsically out-of-equilibrium. This renders their physics far richer than passive colloids and give rise to the emergence of complex phenomena e.g. collective behavior, swarming... I will present experimental demonstration of emergent properties beyond equilibrium.

  15. Immunostimulatory properties and antitumor activities of glucans

    PubMed Central

    VANNUCCI, LUCA; KRIZAN, JIRI; SIMA, PETR; STAKHEEV, DMITRY; CAJA, FABIAN; RAJSIGLOVA, LENKA; HORAK, VRATISLAV; SAIEH, MUSTAFA

    2013-01-01

    New foods and natural biological modulators have recently become of scientific interest in the investigation of the value of traditional medical therapeutics. Glucans have an important part in this renewed interest. These fungal wall components are claimed to be useful for various medical purposes and they are obtained from medicinal mushrooms commonly used in traditional Oriental medicine. The immunotherapeutic properties of fungi extracts have been reported, including the enhancement of anticancer immunity responses. These properties are principally related to the stimulation of cells of the innate immune system. The discovery of specific receptors for glucans on dendritic cells (dectin-1), as well as interactions with other receptors, mainly expressed by innate immune cells (e.g., Toll-like receptors, complement receptor-3), have raised new attention toward these products as suitable therapeutic agents. We briefly review the characteristics of the glucans from mycelial walls as modulators of the immunity and their possible use as antitumor treatments. PMID:23739801

  16. Dosimetric properties of activated lithium tetraborate

    NASA Astrophysics Data System (ADS)

    Majchrowski, Andrzej; Malecki, M.; Zmija, Jozef; Warkocki, Stanislaw; Warkocki, Wodzislaw

    1993-10-01

    This paper describes preliminary investigations of Li2B4O7 thermoluminescent phosphors as candidates for gamma radiation dosimetry materials. Single crystals, glasses, and polycrystals of lithium tetraborate activated with different dopants have been investigated.

  17. Decline of Activity and Quantity of Ribulose Bisphosphate Carboxylase/Oxygenase and Net Photosynthesis in Ozone-Treated Potato Foliage 1

    PubMed Central

    Dann, Michael S.; Pell, Eva J.

    1989-01-01

    The effect of ozone (O3) on ribulose bisphosphate carboxylase/oxygenase (Rubisco) activity and quantity and net photosynthesis in greenhouse-grown Solanum tuberosum L. cv `Norland' foliage was studied in relation to oxidant-induced premature senescence. Plants, 26 days old, were exposed to 0.06 to 0.08 microliters per liter O3 from 1000 to 1600 hours for 4 days in a controlled environment chamber. On day 5, plants were exposed to a 6-hour simulated inversion in which O3 peaked at 0.12 microliters per liter. Net photosynthesis declined in response to O3 but recovered to near control levels 3 days after the exposure ended. Rubisco activity and quantity in control potato foliage increased and then decreased during the 12-day interval of the study. In some experiments foliage studied was physiologically mature and Rubisco activity had peaked when O3 exposure commenced. In those cases, O3 accelerated the decline in Rubisco activity. When less mature foliage was treated with O3, the leaves never achieved the maximal level of Rubisco activity observed in control foliage and also exhibited more rapid decline in initial and total activity. Percent activation of Rubisco (initial/total activity) was not affected significantly by treatment. Quantity of Rubisco decreased in concert with activity. The decrease in activities is most likely due to a decrease in available protein rather than a decrease in the percentage of Rubisco activated in vivo. The reduction in the quantity of Rubisco, an important foliar storage protein, could contribute to premature senescence associated with toxicity of this air pollutant. PMID:16667037

  18. [Study on influence between activated carbon property and immobilized biological activated carbon purification effect].

    PubMed

    Wang, Guang-zhi; Li, Wei-guang; He, Wen-jie; Han, Hong-da; Ding, Chi; Ma, Xiao-na; Qu, Yan-ming

    2006-10-01

    By means of immobilizing five kinds of activated carbon, we studied the influence between the chief activated carbon property items and immobilized bioactivated carbon (IBAC) purification effect with the correlation analysis. The result shows that the activated carbon property items which the correlation coefficient is up 0.7 include molasses, abrasion number, hardness, tannin, uniform coefficient, mean particle diameter and effective particle diameter; the activated carbon property items which the correlation coefficient is up 0.5 include pH, iodine, butane and tetrachloride. In succession, the partial correlation analysis shows that activated carbon property items mostly influencing on IBAC purification effect include molasses, hardness, abrasion number, uniform coefficient, mean particle diameter and effective particle diameter. The causation of these property items bringing influence on IBAC purification is that the activated carbon holes distribution (representative activated carbon property item is molasses) provides inhabitable location and adjust food for the dominance bacteria; the mechanical resist-crash property of activated carbon (representative activated carbon property items: abrasion number and hardness) have influence on the stability of biofilm; and the particle diameter size and distribution of activated carbon (representative activated carbon property items: uniform coefficient, mean particle diameter and effective particle diameter) can directly affect the force of water in IBAC filter bed, which brings influence on the dominance bacteria immobilizing on activated carbon.

  19. Statistical Properties of Extreme Solar Activity Intervals

    NASA Astrophysics Data System (ADS)

    Lioznova, A. V.; Blinov, A. V.

    2014-01-01

    A study of long-term solar variability reflected in indirect indices of past solar activity leads to stimulating results. We compare the statistics of intervals of very low and very high solar activity derived from two cosmogenic radionuclide records and look for consistency in their timing and physical interpretation. According to the applied criteria, the numbers of minima and of maxima are 61 and 68, respectively, from the 10Be record, and 42 and 46 from the 14C record. The difference between the enhanced and depressed states of solar activity becomes apparent in the difference in their statistical distributions. We find no correlation between the level or type (minimum or maximum) of an extremum and the level or type of the predecessor. The hypothesis of solar activity as a periodic process on the millennial time scale is not supported by the existing proxies. A new homogeneous series of 10Be measurements in polar ice covering the Holocene would be of great value for eliminating the existing discrepancy in the available solar activity reconstructions.

  20. Antimalarial properties of orally active iron chelators.

    PubMed

    Heppner, D G; Hallaway, P E; Kontoghiorghes, G J; Eaton, J W

    1988-07-01

    The appearance of widespread multiple drug resistance in human malaria has intensified the search for new antimalarial compounds. Metal chelators, especially those with high affinity for iron, represent one presently unexploited class of antimalarials. Unfortunately the use of previously identified chelators as antimalarials has been precluded by their toxicity and, in the case of desferrioxamine, the necessity for parenteral administration. The investigators now report that a new class of orally active iron chelators, namely the derivatives of alpha-ketohydroxypyridines (KHPs), are potent antimalarials against cultured Plasmodium falciparum. The KHPs evidently exert this effect by sequestering iron because a preformed chelator:iron complex has no antimalarial action. The pool(s) of iron being sequestered by the chelators have not been identified but may not include serum transferrin. Preincubation of human serum with KHPs followed by removal of the drug results in the removal of greater than 97% of total serum iron. Nonetheless, this serum effectively supports the growth of P falciparum cultures. Therefore the KHPs may exert antimalarial effect through chelation of erythrocytic rather than serum iron pool(s). The investigators conclude that these powerful, orally active iron chelators may form the basis of a new class of antimalarial drugs. PMID:3291984

  1. Alkali-activated cementitious materials: Mechanisms, microstructure and properties

    NASA Astrophysics Data System (ADS)

    Jiang, Weimin

    The goal of this study was to examine the activation reaction, microstructure, properties, identify the mechanisms of activation, and achieve an enhanced understanding of activation processes occurring during the synthesis of alkali activated cementitious materials (AAC). The discussions classify the following categories. (1) alkali activated slag cement; (2) alkali activated portland-slag cement; (3) alkali activated fly ash-slag cement; (4) alkali activated pozzolana-lime cement; (5) alkali activated pozzolana cement. The activators involved are NaOH, KOH; Nasb2SOsb4;\\ Nasb2COsb3;\\ CaSOsb4, and soluble silicate of sodium and potassium. The effect of alkali activation on the microstructure of these materials were analyzed at the micro-nanometer scale by SEM, EDS, ESEM, and TEM. Also sp{29}Si and sp{27}Al MAS-NMR, IR, Raman, TGA, and DTA were performed to characterize the phase in these systems. Slag, fly ash, silica fume, as well as blended cements containing mixtures of these and other components were characterized. A set of ordinary portland cement paste samples served as a control. This study confirmed that AAC materials have great potential because they could generate very early high strength, greater durability and high performance. Among the benefits to be derived from this research is a better understanding of the factors that control concrete properties when using AAC materials, and by controlling the chemistry and processing to produce desired microstructures and properties, as well as their durability.

  2. Psychometric Properties of the Commitment to Physical Activity Scale

    ERIC Educational Resources Information Center

    DeBate, Rita DiGioacchino; Huberty, Jennifer; Pettee, Kelley

    2009-01-01

    Objective: To assess psychometric properties of the Commitment to Physical Activity Scale (CPAS). Methods: Girls in third to fifth grades (n = 932) completed the CPAS before and after a physical activity intervention. Psychometric measures included internal consistency, factor analysis, and concurrent validity. Results: Three CPAS factors emerged:…

  3. The BSD2 ortholog in Chlamydomonas reinhardtii is a polysome-associated chaperone that co-migrates on sucrose gradients with the rbcL transcript encoding the Rubisco large subunit.

    PubMed

    Doron, Lior; Segal, Na'ama; Gibori, Hadas; Shapira, Michal

    2014-10-01

    The expression of the CO2 -fixation enzyme ribulose-bisphosphate carboxylase/oxygenase (Rubisco), which is affected by light, involves the cysteine-rich protein bundle-sheath defective-2 (BSD2) that was originally identified in maize bundle-sheath cells. We identified the BSD2 ortholog in Chlamydomonas reinhardtii as a small protein (17 kDa) localized to the chloroplast. The algal BSD2-ortholog contains four CXXCXGXG DnaJ-like elements, but lacks the other conserved domains of DnaJ. BSD2 co-migrated with the rbcL transcript on heavy polysomes, and both BSD2 and rbcL mRNA shifted to the lighter fractions under oxidizing conditions that repress the translation of the Rubisco large subunit (RbcL). This profile of co-migration supports the possibility that BSD2 is required for the de novo synthesis of RbcL. Furthermore, BSD2 co-migrated with the rbcL transcript in a C. reinhardtii premature-termination mutant that encodes the first 60 amino acids of RbcL. In both strains, BSD2 shared its migration profile with the rbcL transcript but not with psbA mRNA. The chaperone activity of BSD2 was exemplified by its ability to prevent the aggregation of both citrate synthase (CS) and RbcL in vitro following their chemical denaturation. This activity did not depend on the presence of the thiol groups on BSD2. In contrast, the activity of BSD2 in preventing the precipitation of reduced β-chains in vitro in the insulin turbidity assay was thiol-dependent. We conclude that BSD2 combines a chaperone 'holdase' function with the ability to interact with free thiols, with both activities being required to protect newly synthesized RbcL chains.

  4. [The effect of physical properties of chitosan on cell activity and on its mechanics property].

    PubMed

    Tian, Shengli; Ye, Zhiyi

    2012-12-01

    Chitosan is a natural biopolymer and is made up of D-glucosamine subunits linked by beta-(1,4) glycosidic bond. In recent years, the application of chitosan has attracted more and more attention because of its good biological function in cell biology. The properties of chitosan-based biomaterial are attributed to the physical properties and chemical composition of chitosan. The author of this paper summarized recent related studies and progresses of the influence of physical properties of chitosan on cell activity and cell mechanics property at home and abroad. The findings show that most studies mainly focused on the influence of chitosan and cell activity, while few were on cell mechanics property. The related studies of the influence of chitosan on cell will contribute to the explanation for the mechanism of the interaction between chitosan and cell, and provide the theoretical support for the further study.

  5. Decline of activity and quantity of ribulose bisphosphate carboxylase/oxygenase and net photosynthesis in ozone-treated potato foliage

    SciTech Connect

    Dann, M.S.; Pell, E.J. )

    1989-09-01

    The effect of ozone (O{sub 3}) on ribulose bisphosphate carboxylase/oxygenase (Rubisco) activity and quantity and net photosynthesis in greenhouse-grown Solanum tuberosum L. cv Norland foliage was studied in relation to oxidant-induced premature senescence. Plants, 26 days old, were exposed to 0.06 to 0.08 microliters per liter O{sub 3} from 1,000 to 1,600 hours for 4 days in a controlled environment chamber. On day 5, plants were exposed to a 6-hour simulated inversion in which O{sub 3} peaked at 0.12 microliters per liter. Net photosynthesis declined in response to O{sub 3} but recovered to near control levels 3 days after the exposure ended. Rubisco activity and quantity in control potato foliage increased and then decreased during the 12-day interval of the study. In some experiments foliage studied was physiologically mature and Rubisco activity had peaked when O{sub 3} exposure commenced. In those cases, O{sub 3} accelerated the decline in Rubisco activity. When less mature foliage was treated with O{sub 3}, the leaves never achieved the maximal level of Rubisco activity observed in control foliage and also exhibited more rapid decline in initial and total activity. Percent activation of Rubisco (initial/total activity) was not affected significantly by treatment. Quantity of Rubisco decreased in concert with activity. The reduction in the quantity of Rubisco, an important foliage storage protein, could contribute to premature senescence associated with toxicity of this air pollutant.

  6. Workability and mechanical properties of alkali activated slag concrete

    SciTech Connect

    Collins, F.G.; Sanjayan, J.G.

    1999-03-01

    This paper reports the results of an investigation on concrete containing alkali activated slag (AAS) as the binder, with emphasis on achievement of reasonable workability and equivalent one-day strength to portland cement concrete at normal curing temperatures. Two types of activators were used: sodium hydroxide in combination with sodium carbonate and sodium silicate in combination with hydrated lime. The fresh concrete properties reported include slump and slump loss, air content, and bleed. Mechanical properties of AAS concrete, including compressive strength, elastic modulus, flexural strength, drying shrinkage, and creep are contrasted with those of portland cement concrete.

  7. Study of Stevia rebaudiana Bertoni antioxidant activities and cellular properties.

    PubMed

    Bender, Cecilia; Graziano, Sara; Zimmermann, Benno F

    2015-01-01

    The aim of our study was to determine the antioxidant activities, cytotoxicity and proliferative properties in Stevia rebaudiana leaves and stems. Leaves extracts exhibited a higher antioxidant activity than stems extract, through oxygen radical absorbance capacity (ORAC) and cellular antioxidant activity (CAA) assays. Stevioside and rebaudioside A, the main sweetening metabolites in stevia leaves, exhibited a low ORAC value in comparison with plant extracts, while did not elicit any CAA. Stevia rebaudiana did not exhibit toxicity against HepG2 (hepatocellular carcinoma) human cells. No proliferative nor catalase modulations were observed in cells treated with such extracts. Our findings support the promising role of stevia that, apart from its sweetness, can act as a source of antioxidants, even at the intracellular level. This activity makes S. rebaudiana crude extract an interesting resource of natural sweetness with antioxidant properties which may find numerous applications in foods and nutritional supplements industries. PMID:26008718

  8. Study of Stevia rebaudiana Bertoni antioxidant activities and cellular properties.

    PubMed

    Bender, Cecilia; Graziano, Sara; Zimmermann, Benno F

    2015-01-01

    The aim of our study was to determine the antioxidant activities, cytotoxicity and proliferative properties in Stevia rebaudiana leaves and stems. Leaves extracts exhibited a higher antioxidant activity than stems extract, through oxygen radical absorbance capacity (ORAC) and cellular antioxidant activity (CAA) assays. Stevioside and rebaudioside A, the main sweetening metabolites in stevia leaves, exhibited a low ORAC value in comparison with plant extracts, while did not elicit any CAA. Stevia rebaudiana did not exhibit toxicity against HepG2 (hepatocellular carcinoma) human cells. No proliferative nor catalase modulations were observed in cells treated with such extracts. Our findings support the promising role of stevia that, apart from its sweetness, can act as a source of antioxidants, even at the intracellular level. This activity makes S. rebaudiana crude extract an interesting resource of natural sweetness with antioxidant properties which may find numerous applications in foods and nutritional supplements industries.

  9. Environment and properties of obscured and unobscured active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Taormina, M.; Bornancini, C.

    We analyze the properties of obscured and unobscured active galactic nuclei selected using mid-infrared colors in the redshift range 1 < z < 3. We find that obscured objects are located in a denser local galaxy environment compared to the unobscured sample.

  10. Interactive effects of and light on growth rates and RUBISCO content of small and large centric diatoms

    NASA Astrophysics Data System (ADS)

    Li, G.; Campbell, D. A.

    2015-10-01

    Among marine phytoplankton groups, diatoms span the widest range of cell size, with resulting effects upon their nitrogen uptake, photosynthesis and growth responses to light. We grew two strains of marine centric diatoms, the small Thalassiosira pseudonana and the larger T. punctigera in high and low nitrogen media, across a range of growth light levels. Nitrogen and total proteins per cell decreased with increasing growth light in both species when grown under low nitrogen media. Surprisingly, low nitrogen increased the cellular allocation to RUBISCO and the rate of electron transport away from Photosystem II for the smaller diatom under low growth light, and for the larger diatom across the range of growth lights. Low nitrogen decreased the growth rate of the smaller diatom, particularly under higher light, but stimulated the growth rate of the larger diatom. Our results show that the high nitrogen in common growth media favours the growth rate of a small diatom but inhibits growth of a larger species.

  11. Relationship between anticoagulant activities and polyanionic properties of rabbit thrombomodulin.

    PubMed

    Bourin, M C; Ohlin, A K; Lane, D A; Stenflo, J; Lindahl, U

    1988-06-15

    Rabbit thrombomodulin displays three distinct blood anticoagulant activities: it promotes the activation of protein C by thrombin (protein C activation cofactor activity); it promotes the inactivation of thrombin by thrombin (direct anticoagulant activity). The effects on these activities of mouse anti-thrombomodulin monoclonal antibodies and of the heparin-neutralizing proteins, platelet factor 4, histidine-rich glycoprotein, and S-protein, were investigated. One of the antibodies, which did not influence the functional properties of thrombomodulin, was used as an immunoaffinity ligand for purification of the protein. Two other antibodies, which were found to abrogate the protein C activation cofactor activity of the purified thrombomodulin, also abolished the antithrombin-dependent and the direct anticoagulant activities. The heparin-neutralizing proteins all inhibited the two latter activities, albeit to a varying extent, but did not appreciably affect the activation of protein C. These results are interpreted in relation to our previous finding that rabbit thrombomodulin contains an acidic domain, tentatively identified as a sulfated glycosaminoglycan (Bourin, M.-C., Boffa, M.-C., Björk, I., and Lindahl, U. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 5924-5928). It is proposed that the acidic domain interacts with thrombin at the protein C activation site and that this interaction is a prerequisite to the expression of direct as well as antithrombin-dependent anticoagulant activity. The interaction is not essential to, but compatible with, the activation of protein C. Experiments involving treatment of thrombomodulin with various glycanases or with nitrous acid, followed by measurement of anticoagulant activities, indicated that the acidic domain is constituted by a sulfated galactosaminoglycan and not by a heparin-related polysaccharide as previously suggested.

  12. Effects of Soil Property Uncertainty on Projected Active Layer Thickness

    NASA Astrophysics Data System (ADS)

    Harp, D. R.; Atchley, A. L.; Coon, E.; Painter, S. L.; Wilson, C. J.; Romanovsky, V. E.; Liljedahl, A.

    2014-12-01

    Uncertainty in future climate is often assumed to contribute the largest uncertainty to active layer thickness (ALT) projections. However, the impact of soil property uncertainty on these projections may be significant. In this research, we evaluate the contribution of soil property uncertainty on ALT projections at the Barrow Environmental Observatory, Alaska. The effect of variations in porosity, thermal conductivity, saturation, and water retention properties of peat and mineral soil are evaluated. The micro-topography of ice wedge polygons present at the site is included in the analysis using three 1D column models to represent polygon center, rim and trough features. The Arctic Terrestrial Simulator (ATS) is used to model multiphase thermal and hydrological processes in the subsurface. We apply the Null-Space Monte Carlo (NSMC) algorithm to identify an ensemble of soil property combinations that produce simulated temperature profiles that are consistent with temperature measurements available from the site. ALT is simulated for the ensemble of soil property combinations for four climate scenarios. The uncertainty in ALT due to soil properties within and across climate scenarios is evaluated. This work was supported by LANL Laboratory Directed Research and Development Project LDRD201200068DR and by the The Next-Generation Ecosystem Experiments (NGEE Arctic) project. NGEE-Arctic is supported by the Office of Biological and Environmental Research in the DOE Office of Science.

  13. Comparative study of surface-active properties and antimicrobial activities of disaccharide monoesters.

    PubMed

    Zhang, Xi; Song, Fei; Taxipalati, Maierhaba; Wei, Wei; Feng, Fengqin

    2014-01-01

    The objective of this research was to determine the effect of sugar or fatty acid in sugar ester compounds on the surface-active properties and antimicrobial activities of these compounds. Disaccharides of medium-chain fatty acid monoesters were synthesized through transesterifications by immobilized lipase (Lipozyme TLIM) to yield nine monoesters for subsequent study. Their antimicrobial activities were investigated using three pathogenic microorganisms: Staphylococcus aureus, Escherichia coli O157:H7 and Candida albicans. Their surface-active properties including air-water surface tension, critical micelle concentration, and foaming and emulsion power and stability were also studied. The results showed that all of the tested monoesters were more effective against Staphylococcus aureus (Gram-positive bacterium) than against Escherichia coli O157:H7 (Gram-negative bacterium). The results demonstrated that the carbon chain length was the most important factor influencing the surface properties, whereas degree of esterification and hydrophilic groups showed little effect.

  14. Comparative Study of Surface-Active Properties and Antimicrobial Activities of Disaccharide Monoesters

    PubMed Central

    Zhang, Xi; Song, Fei; Taxipalati, Maierhaba; Wei, Wei; Feng, Fengqin

    2014-01-01

    The objective of this research was to determine the effect of sugar or fatty acid in sugar ester compounds on the surface-active properties and antimicrobial activities of these compounds. Disaccharides of medium-chain fatty acid monoesters were synthesized through transesterifications by immobilized lipase (Lipozyme TLIM) to yield nine monoesters for subsequent study. Their antimicrobial activities were investigated using three pathogenic microorganisms: Staphylococcus aureus, Escherichia coli O157:H7 and Candida albicans. Their surface-active properties including air–water surface tension, critical micelle concentration, and foaming and emulsion power and stability were also studied. The results showed that all of the tested monoesters were more effective against Staphylococcus aureus (Gram-positive bacterium) than against Escherichia coli O157:H7 (Gram-negative bacterium). The results demonstrated that the carbon chain length was the most important factor influencing the surface properties, whereas degree of esterification and hydrophilic groups showed little effect. PMID:25531369

  15. Mechanical properties characterization and modeling of active polymer gels

    NASA Astrophysics Data System (ADS)

    Marra, Steven Paul

    Active polymer gels expand and contract in response to certain environmental stimuli, such as the application of an electric field or a change in the pH level of the surroundings. This ability to achieve large, reversible deformations with no external mechanical loading has generated much interest in the use of these gels as actuators and "artificial muscles." While much work has been done to study the behavior and properties of these gels, little information is available regarding the full constitutive description of the mechanical and actuation properties. This work focuses on developing a means of characterizing the mechanical properties of active polymer gels and describing how these properties evolve as the gel actuates. Poly(vinyl alcohol)-poly(acrylic acid) (PVA-PAA) gel was chosen as the model material for this work because it is relatively simple and safe to both fabricate and actuate. PVA-PAA gels are fabricated on-site using a solvent-casting technique. These gels expand when moved from acidic to basic solutions, and contract when moved from basic to acidic solutions. Citric acid and sodium bicarbonate were used as the testing solutions for this work. The mechanical properties of the gel were characterized by conducting uniaxial and biaxial tests on thin PVA-PAA gel films. A biaxial testing system has been developed which can measure stresses and deformations of these films in a variety of liquid environments. The experimental results on PVA-PAA gels show these materials to be relatively compliant, and slightly viscoelastic and compressible. These gels are also capable of large recoverable deformations in both acidic and basic environments. A thermodynamically consistent finite-elastic constitutive model was developed to describe the mechanical and actuation behaviors of active polymer gels. The mechanical properties of the gel are characterized by a free-energy function, and the model utilizes an evolving internal variable to describe the actuation

  16. Antioedematogenic activity, acetylcholinesterase inhibition and antimicrobial properties of Jacaranda oxyphylla.

    PubMed

    Pereira, V V; Silva, R R; Dos Santos, M H; Dias, D F; Moreira, M E C; Takahashi, J A

    2016-09-01

    Jacaranda oxyphylla Cham. (Bignoniaceae) is a shrub found in the Brazilian cerrado and used in folk medicine to treat microbial infections. The aim of this study was to carry out a phytochemical screening and evaluate antioedematogenic, antimicrobial and antiacetylcholinesterase properties of J. oxyphylla crude extracts. All extracts analysed showed presence of terpenoids, which are potentially active chemical substances. A high AChE inhibitory activity for hexane extract from leaves and for the extracts from twigs was found. Ethanol extract from leaves of J. oxyphylla showed activity against Gram-positive (Staphylococcus aureus and Bacillus cereus) and Gram-negative (Escherichia coli) bacteria. This extract was also effective in inhibiting the stages of inflammation evaluated. Biological investigation and phytochemical screening of J. oxyphylla extracts provided additional evidence of its traditional medicinal value.

  17. Protonophore properties of hyperforin are essential for its pharmacological activity

    PubMed Central

    Sell, Thomas S.; Belkacemi, Thabet; Flockerzi, Veit; Beck, Andreas

    2014-01-01

    Hyperforin is a pharmacologically active component of the medicinal plant Hypericum perforatum (St. John's wort), recommended as a treatment for a range of ailments including mild to moderate depression. Part of its action has been attributed to TRPC6 channel activation. We found that hyperforin induces TRPC6-independent H+ currents in HEK-293 cells, cortical microglia, chromaffin cells and lipid bilayers. The latter demonstrates that hyperforin itself acts as a protonophore. The protonophore activity of hyperforin causes cytosolic acidification, which strongly depends on the holding potential, and which fuels the plasma membrane sodium-proton exchanger. Thereby the free intracellular sodium concentration increases and the neurotransmitter uptake by Na+ cotransport is inhibited. Additionally, hyperforin depletes and reduces loading of large dense core vesicles in chromaffin cells, which requires a pH gradient in order to accumulate monoamines. In summary the pharmacological actions of the “herbal Prozac” hyperforin are essentially determined by its protonophore properties shown here. PMID:25511254

  18. Protonophore properties of hyperforin are essential for its pharmacological activity.

    PubMed

    Sell, Thomas S; Belkacemi, Thabet; Flockerzi, Veit; Beck, Andreas

    2014-01-01

    Hyperforin is a pharmacologically active component of the medicinal plant Hypericum perforatum (St. John's wort), recommended as a treatment for a range of ailments including mild to moderate depression. Part of its action has been attributed to TRPC6 channel activation. We found that hyperforin induces TRPC6-independent H(+) currents in HEK-293 cells, cortical microglia, chromaffin cells and lipid bilayers. The latter demonstrates that hyperforin itself acts as a protonophore. The protonophore activity of hyperforin causes cytosolic acidification, which strongly depends on the holding potential, and which fuels the plasma membrane sodium-proton exchanger. Thereby the free intracellular sodium concentration increases and the neurotransmitter uptake by Na(+) cotransport is inhibited. Additionally, hyperforin depletes and reduces loading of large dense core vesicles in chromaffin cells, which requires a pH gradient in order to accumulate monoamines. In summary the pharmacological actions of the "herbal Prozac" hyperforin are essentially determined by its protonophore properties shown here. PMID:25511254

  19. Biological and therapeutic activities, and anticancer properties of curcumin

    PubMed Central

    PERRONE, DONATELLA; ARDITO, FATIMA; GIANNATEMPO, GIOVANNI; DIOGUARDI, MARIO; TROIANO, GIUSEPPE; LO RUSSO, LUCIO; DE LILLO, ALFREDO; LAINO, LUIGI; LO MUZIO, LORENZO

    2015-01-01

    Curcumin (diferuloylmethane) is a polyphenol derived from the Curcuma longa plant. Curcumin has been used extensively in Ayurvedic medicine, as it is nontoxic and exhibits a variety of therapeutic properties, including antioxidant, analgesic, anti-inflammatory and antiseptic activities. Recently, certain studies have indicated that curcumin may exert anticancer effects in a variety of biological pathways involved in mutagenesis, apoptosis, tumorigenesis, cell cycle regulation and metastasis. The present study reviewed previous studies in the literature, which support the therapeutic activity of curcumin in cancer. In addition, the present study elucidated a number of the challenges concerning the use of curcumin as an adjuvant chemotherapeutic agent. All the studies reviewed herein suggest that curcumin is able to exert anti-inflammatory, antiplatelet, antioxidative, hepatoprotective and antitumor activities, particularly against cancers of the liver, skin, pancreas, prostate, ovary, lung and head neck, as well as having a positive effect in the treatment of arthritis. PMID:26640527

  20. Active doublet method for measuring small changes in physical properties

    DOEpatents

    Roberts, Peter M.; Fehler, Michael C.; Johnson, Paul A.; Phillips, W. Scott

    1994-01-01

    Small changes in material properties of a work piece are detected by measuring small changes in elastic wave velocity and attenuation within a work piece. Active, repeatable source generate coda wave responses from a work piece, where the coda wave responses are temporally displaced. By analyzing progressive relative phase and amplitude changes between the coda wave responses as a function of elapsed time, accurate determinations of velocity and attenuation changes are made. Thus, a small change in velocity occurring within a sample region during the time periods between excitation origin times (herein called "doublets") will produce a relative delay that changes with elapsed time over some portion of the scattered waves. This trend of changing delay is easier to detect than an isolated delay based on a single arrival and provides a direct measure of elastic wave velocity changes arising from changed material properties of the work piece.

  1. Brain mechanical property measurement using MRE with intrinsic activation

    NASA Astrophysics Data System (ADS)

    Weaver, John B.; Pattison, Adam J.; McGarry, Matthew D.; Perreard, Irina M.; Swienckowski, Jessica G.; Eskey, Clifford J.; Lollis, S. Scott; Paulsen, Keith D.

    2012-11-01

    , termed intrinsic activation, produces sufficient motion to allow mechanical properties to be recovered. The poroelastic model is more consistent with the measured data from brain at low frequencies than the linear elastic model. Intrinsic activation allows MRE to be performed without a device shaking the head so the patient notices no differences between it and the other sequences in an MR examination.

  2. Faster Rubisco Is the Key to Superior Nitrogen-Use Efficiency in NADP-Malic Enzyme Relative to NAD-Malic Enzyme C4 Grasses1

    PubMed Central

    Ghannoum, Oula; Evans, John R.; Chow, Wah Soon; Andrews, T. John; Conroy, Jann P.; von Caemmerer, Susanne

    2005-01-01

    In 27 C4 grasses grown under adequate or deficient nitrogen (N) supplies, N-use efficiency at the photosynthetic (assimilation rate per unit leaf N) and whole-plant (dry mass per total leaf N) level was greater in NADP-malic enzyme (ME) than NAD-ME species. This was due to lower N content in NADP-ME than NAD-ME leaves because neither assimilation rates nor plant dry mass differed significantly between the two C4 subtypes. Relative to NAD-ME, NADP-ME leaves had greater in vivo (assimilation rate per Rubisco catalytic sites) and in vitro Rubisco turnover rates (kcat; 3.8 versus 5.7 s−1 at 25°C). The two parameters were linearly related. In 2 NAD-ME (Panicum miliaceum and Panicum coloratum) and 2 NADP-ME (Sorghum bicolor and Cenchrus ciliaris) grasses, 30% of leaf N was allocated to thylakoids and 5% to 9% to amino acids and nitrate. Soluble protein represented a smaller fraction of leaf N in NADP-ME (41%) than in NAD-ME (53%) leaves, of which Rubisco accounted for one-seventh. Soluble protein averaged 7 and 10 g (mmol chlorophyll)−1 in NADP-ME and NAD-ME leaves, respectively. The majority (65%) of leaf N and chlorophyll was found in the mesophyll of NADP-ME and bundle sheath of NAD-ME leaves. The mesophyll-bundle sheath distribution of functional thylakoid complexes (photosystems I and II and cytochrome f) varied among species, with a tendency to be mostly located in the mesophyll. In conclusion, superior N-use efficiency of NADP-ME relative to NAD-ME grasses was achieved with less leaf N, soluble protein, and Rubisco having a faster kcat. PMID:15665246

  3. Psychometric properties of the Arab Heritage Activity Card Sort.

    PubMed

    Hamed, Razan; Holm, Margo B

    2013-03-01

    The Activity Card Sort is a valid and reliable assessment tool that was created to assess Participation. It has been translated to several languages and adapted to different international cultures. The most recent version of this tool is the Arabic Heritage Activity Card Sort (A-ACS). The purpose of this study was to establish the psychometric properties of the new Arabic version in Jordanian adults. Forty three Jordanian patients with multiple sclerosis (MS) and 62 healthy adults were recruited to test the psychometric properties of the tool. The A-ACS correlated moderately with the participation index of the Mayo-Portland Adaptability Inventory (r = -0.458, p < 0.00) (concurrent validity), was able to discriminate between patients and healthy participants on the current and retained levels of participation (F = 5.09, p < 0.03; F = 6.01, p < 0.02, respectively) (discriminative validity), and correlated moderately with the total scores of the Mayo-Portland Adaptability Inventory (r = -0.458, p < 0.00) and the total score on the Arabic version of the self-report Performance Assessment of Self-care Skills (r = 0.581, p < 0.00) (convergent validity). The tool also showed good test-retest reliability (r = 0.80, p < 0.00) and excellent internal consistency (α = 0.90). The Arabic Heritage of the Activity Card Sort is a valid and reliable tool for Arabic-speaking occupational therapists to use when assessing participation in Jordanian patients with MS or healthy adults. Limitations of this study include using only one diagnostic group from Jordan and examining only the Recovery and Community Versions of the tool. Future studies are needed to examine further psychometric properties for patients with different diagnoses and from different countries in the Arabic region for all three versions of the A-ACS.

  4. Manipulating lipid bilayer material properties using biologically active amphipathic molecules

    NASA Astrophysics Data System (ADS)

    Ashrafuzzaman, Md; Lampson, M. A.; Greathouse, D. V.; Koeppe, R. E., II; Andersen, O. S.

    2006-07-01

    Lipid bilayers are elastic bodies with properties that can be manipulated/controlled by the adsorption of amphipathic molecules. The resulting changes in bilayer elasticity have been shown to regulate integral membrane protein function. To further understand the amphiphile-induced modulation of bilayer material properties (thickness, intrinsic monolayer curvature and elastic moduli), we examined how an enantiomeric pair of viral anti-fusion peptides (AFPs)—Z-Gly-D-Phe and Z-Gly-Phe, where Z denotes a benzyloxycarbonyl group, as well as Z-Phe-Tyr and Z-D-Phe-Phe-Gly—alters the function of enantiomeric pairs of gramicidin channels of different lengths in planar bilayers. For both short and long channels, the channel lifetimes and appearance frequencies increase as linear functions of the aqueous AFP concentration, with no apparent effect on the single-channel conductance. These changes in channel function do not depend on the chirality of the channels or the AFPs. At pH 7.0, the relative changes in channel lifetimes do not vary when the channel length is varied, indicating that these compounds exert their effects primarily by causing a positive-going change in the intrinsic monolayer curvature. At pH 4.0, the AFPs are more potent than at pH 7.0 and have greater effects on the shorter channels, indicating that these compounds now change the bilayer elastic moduli. When AFPs of different anti-fusion potencies are compared, the rank order of the anti-fusion activity and the channel-modifying activity is similar, but the relative changes in anti-fusion potency are larger than the changes in channel-modifying activity. We conclude that gramicidin channels are useful as molecular force transducers to probe the influence of small amphiphiles upon lipid bilayer material properties.

  5. Immunoenhancing properties and antiviral activity of 7-deazaguanosine in mice.

    PubMed Central

    Smee, D F; Alaghamandan, H A; Gilbert, J; Burger, R A; Jin, A; Sharma, B S; Ramasamy, K; Revankar, G R; Cottam, H B; Jolley, W B

    1991-01-01

    The nucleotide analog 7-deazaguanosine has not previously been reported to possess biological (antiviral or antitumor) properties in cell culture or in vivo. Up to 10(5) U of interferon per ml was detected in mouse sera 1 to 4 h following oral (200-mg/kg of body weight) and intraperitoneal (50-mg/kg) doses of the compound. 7-Deazaguanosine also caused significant activation of natural killer and phagocytic cells but did not augment T- and B-cell blastogenesis. Intraperitoneal treatments of 50, 100, and 200 mg/kg/day administered 24 and 18 h before virus inoculation were highly protective in mice inoculated with lethal doses of Semliki Forest or San Angelo viruses. Less but still significant survivor increases were evident in treated mice infected with banzi or encephalomyocarditis viruses. In most cases, the degree of antiviral activity was similar to that exhibited by the biological response modifier 7-thia-8-oxoguanosine. 7-Thia-8-oxoguanosine was more potent than 7-deazaguanosine against encephalomyocarditis virus in mice, however. Oral efficacy was achieved with 7-deazaguanosine treatments of greater than or equal to 100 mg/kg against all virus infections, whereas 7-thia-8-oxoguanosine is reported to be devoid of oral activity in rodents. Thus, 7-deazaguanosine represents the first reported orally active nucleoside biological response modifier exhibiting broad-spectrum antiviral activity against particular types of RNA viruses. PMID:1707603

  6. Swarming Bristle-Bots: Exploring Properties of Active Matter

    NASA Astrophysics Data System (ADS)

    Forstner, Martin B.; Beasock, Damian

    Active Matter describes an ubiquitous class of non-equilibrium systems that encompasses a diverse range of phenomena in the living and non-living realm. Examples are microscopic bio-filaments and their associated motor proteins, flocks of birds and fish, vibrated rods and disks, or nanoscale colloids actuated by catalytic activity on their surface. What unifies these systems is that they are all composed of self-driven units. In consequence, these systems are not driven into non-equilibrium by energy input at their boundary, but by local energy injection. As fascinating as these systems are, there are currently barely any laboratory systems that allow for controlled experiments in dry active matter. That is, systems not immersed in a fluid that can be observed without specialized equipment. Here we present a two-dimensional `active matter' system consisting of hundreds of macroscopic (~0.05 m long), modified, commercially available bristle-bots. We show that this swarm of toys classifies as active matter as it exhibits properties such as dynamic phase separation. Because of their straight forward implementation, their size and controllability, such swarms can not only answer scientific questions, but they have great potential as educational tools in teaching labs and classrooms.

  7. The coupling of glycolysis and the Rubisco-based pathway through the non-oxidative pentose phosphate pathway to achieve low carbon dioxide emission fermentation.

    PubMed

    Li, Ya-Han; Ou-Yang, Fan-Yu; Yang, Cheng-Han; Li, Si-Yu

    2015-01-01

    In this study, Rubisco-based engineered Escherichia coli, containing two heterologous enzymes of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and phosphoribulokinase (PrkA), has been shown to be capable of the in situ recycling of carbon dioxide (CO2) during glycolysis. Two alternative approaches have been proposed to further enhance the carbon flow from glycolysis to a Rubisco-based pathway through the non-oxidative pentose phosphate pathway (NOPPP). The first is achieved by elevating the expression of transketolase I (TktA) and the second by blocking the native oxidation-decarboxylation reaction of E. coli by deleting the zwf gene from the chromosome (designated as JB/pTA and MZB, respectively). Decreases in the CO2 yield and the CO2 evolution per unit mole of ethanol production by at least 81% and 40% are observed. It is demonstrated in this study that the production of one mole of ethanol using E. coli strain MZB, the upper limit of CO2 emission is 0.052mol.

  8. Biological activities and medicinal properties of Gokhru (Pedalium murex L.).

    PubMed

    Rajashekar, V; Rao, E Upender; P, Srinivas

    2012-07-01

    Bada Gokhru (Pedalium murex L.) is perhaps the most useful traditional medicinal plant in India. Each part of the neem tree has some medicinal property and is thus commercially exploitable. During the last five decades, apart from the chemistry of the Pedalium murex compounds, considerable progress has been achieved regarding the biological activity and medicinal applications of this plant. It is now considered as a valuable source of unique natural products for development of medicines against various diseases and also for the development of industrial products. This review gives a bird's eye view mainly on the biological activities of some of this compounds isolated, pharmacological actions of the extracts, clinical studies and plausible medicinal applications of gokharu along with their safety evaluation.

  9. Rocket effluent - Its ice nucleation activity and related properties

    NASA Technical Reports Server (NTRS)

    Parungo, F. P.; Allee, P. A.

    1978-01-01

    To investigate the possibility of inadvertent weather modification from rocket effluent, aerosol samples were collected from an instrumented aircraft subsequent to the Voyager I and II launches. The aerosol's morphology, concentration and size distribution were examined with an electron microscope. The elemental compositions of individual particles were analyzed with an X-ray energy spectrometer. Ice nucleus concentration was measured with a subfreezing thermal diffusion chamber. The particles' physical and chemical properties were related to their ice nucleation activity. A laboratory experiment on rocket propellant exhaust was conducted under controlled conditions. Both laboratory and field experimental results indicated that rocket propellant exhaust can produce active ice nuclei. Their consequences for potential inadvertant weather modification demand additional study.

  10. Rocket effluent: Its ice nucleation activity and related properties

    NASA Technical Reports Server (NTRS)

    Parungo, F. P.; Allee, P. A.

    1978-01-01

    To investigate the possibility of inadvertent weather modification from rocket effluent, aerosol samples were collected from an instrumented aircraft subsequent to the Voyager 1 and 2 launches. The aerosol's morphology, concentration, and size distribution were examined with an electron microscope. The elemental compositions of individual particles were analyzed with an X-ray energy spectrometer. Ice nucleus concentration was measured with a thermal diffusion chamber. The particles' physical and chemical properties were related to their ice nucleation activity. A laboratory experiment on rocket propellant exhaust was conducted under controlled conditions. Both laboratory and field experimental results indicated that rocket propellant exhaust can produce active ice nuclei and modify local weather in suitable meteorological conditions.

  11. Biological activities and medicinal properties of Gokhru (Pedalium murex L.)

    PubMed Central

    Rajashekar, V; Rao, E Upender; P, Srinivas

    2012-01-01

    Bada Gokhru (Pedalium murex L.) is perhaps the most useful traditional medicinal plant in India. Each part of the neem tree has some medicinal property and is thus commercially exploitable. During the last five decades, apart from the chemistry of the Pedalium murex compounds, considerable progress has been achieved regarding the biological activity and medicinal applications of this plant. It is now considered as a valuable source of unique natural products for development of medicines against various diseases and also for the development of industrial products. This review gives a bird's eye view mainly on the biological activities of some of this compounds isolated, pharmacological actions of the extracts, clinical studies and plausible medicinal applications of gokharu along with their safety evaluation. PMID:23569975

  12. Reexamination of the Three-Dimensional Structure of the Small Subunit of RuBisCo from Higher Plants

    NASA Astrophysics Data System (ADS)

    Knight, Stefan; Andersson, Inger; Branden, Carl-Ivar

    1989-05-01

    The structure of L8S8 RuBisCo (where L is the large subunit and S is the small subunit) from spinach has been determined to a resolution of 2.8 angstrom by using fourfold averaging of an isomorphous electron density map based on three heavy-atom derivatives. The structure of the S subunit is different from that previously reported for the tobacco S subunit in spite of 75 percent sequence identity. The elements of secondary structure, four antiparallel β strands and two α helices, are the same, but the topology and direction of the polypeptide chain through these elements differ completely. One of these models is clearly wrong. The spinach model has hydrophobic residues in the core between the α helices and β sheet as well as conserved residues in the subunit interactions. The deletion of residues 49 to 62 that is present in the Anabaena sequence removes a loop region in the spinach model. The positions of three mercury atoms in the heavy-atom derivatives agree with the assignment of side chains in the spinach structure.

  13. The Rubisco Small Subunit Is Involved in Tobamovirus Movement and Tm-22-Mediated Extreme Resistance1[C][W][OA

    PubMed Central

    Zhao, Jinping; Liu, Qi; Zhang, Haili; Jia, Qi; Hong, Yiguo; Liu, Yule

    2013-01-01

    The multifunctional movement protein (MP) of Tomato mosaic tobamovirus (ToMV) is involved in viral cell-to-cell movement, symptom development, and resistance gene recognition. However, it remains to be elucidated how ToMV MP plays such diverse roles in plants. Here, we show that ToMV MP interacts with the Rubisco small subunit (RbCS) of Nicotiana benthamiana in vitro and in vivo. In susceptible N. benthamiana plants, silencing of NbRbCS enabled ToMV to induce necrosis in inoculated leaves, thus enhancing virus local infectivity. However, the development of systemic viral symptoms was delayed. In transgenic N. benthamiana plants harboring Tobacco mosaic virus resistance-22 (Tm-22), which mediates extreme resistance to ToMV, silencing of NbRbCS compromised Tm-22-dependent resistance. ToMV was able to establish efficient local infection but was not able to move systemically. These findings suggest that NbRbCS plays a vital role in tobamovirus movement and plant antiviral defenses. PMID:23148080

  14. Missense mutation in the Chlamydomonas chloroplast gene that encodes the Rubisco large subunit

    SciTech Connect

    Spreitzer, R.J.; Brown, T.; Chen, Zhixiang; Zhang, Donghong; Al-Abed, S.R. )

    1988-04-01

    The 69-12Q mutant of Chlamydomonas reinhardtii lacks ribulose-1,5-bisphosphate carboxylase activity, but retains holoenzyme protein. It results from a mutation in the chloroplast large-subunit gene that causes an isoleucine-for-threonine substitution at amino-acid residue 173. Considering that lysine-175 is involved in catalysis, it appears that mutations cluster at the active site.

  15. Enhanced capacitive properties of commercial activated carbon by re-activation in molten carbonates

    NASA Astrophysics Data System (ADS)

    Lu, Beihu; Xiao, Zuoan; Zhu, Hua; Xiao, Wei; Wu, Wenlong; Wang, Dihua

    2015-12-01

    Simple, affordable and green methods to improve capacitive properties of commercial activated carbon (AC) are intriguing since ACs possess a predominant role in the commercial supercapacitor market. Herein, we report a green reactivation of commercial ACs by soaking ACs in molten Na2CO3-K2CO3 (equal in mass ratios) at 850 °C combining the merits of both physical and chemical activation strategies. The mechanism of molten carbonate treatment and structure-capacitive activity correlations of the ACs are rationalized. Characterizations show that the molten carbonate treatment increases the electrical conductivity of AC without compromising its porosity and wettability of electrolytes. Electrochemical tests show the treated AC exhibited higher specific capacitance, enhanced high-rate capability and excellent cycle performance, promising its practical application in supercapacitors. The present study confirms that the molten carbonate reactivation is a green and effective method to enhance capacitive properties of ACs.

  16. Properties of light reflected from road signs in active imaging.

    PubMed

    Halstuch, Aviran; Yitzhaky, Yitzhak

    2008-08-01

    Night vision systems in vehicles are a new emerging technology. A crucial problem in active (laser-based) systems is distortion of images by saturation and blooming due to strong retroreflections from road signs. We quantify this phenomenon. We measure the Mueller matrices and the polarization state of the reflected light from three different types of road sign commonly used. Measurements of the reflected intensity are also taken with respect to the angle of reflection. We find that different types of sign have different reflection properties. It is concluded that the optimal solution for attenuating the retroreflected intensity is using a linear polarized light source and a linear polarizer with perpendicular orientation (with regard to the source) at the detector. Unfortunately, while this solution performs well for two types of road sign, it is less efficient for the third sign type. PMID:18670559

  17. Lipoprotein electrostatic properties regulate hepatic lipase association and activity.

    PubMed

    Boucher, Jonathan G; Nguyen, Trang; Sparks, Daniel L

    2007-12-01

    The effect of lipoprotein electrostatic properties on the catalytic regulation of hepatic lipase (HL) was investigated. Enrichment of serum or very low density lipoprotein (VLDL) with oleic acid increased lipoprotein negative charge and stimulated lipid hydrolysis by HL. Similarly, enrichment of serum or isolated lipoproteins with the anionic phospholipids phosphatidylinositol (PI), phosphatidic acid, or phosphatidylserine also increased lipoprotein negative charge and stimulated hydrolysis by HL. Anionic lipids had a small effect on phospholipid hydrolysis, but significantly stimulated triacylglyceride (TG) hydrolysis. High density lipoprotein (HDL) charge appears to have a specific effect on lipolysis. Enrichment of HDL with PI significantly stimulated VLDL-TG hydrolysis by HL. To determine whether HDL charge affects the association of HL with HDL and VLDL, HL-lipoprotein interactions were probed immunochemically. Under normal circumstances, HL associates with HDL particles, and only small amounts bind to VLDL. PI enrichment of HDL blocked the binding of HL with HDL. These data indicate that increasing the negative charge of HDL stimulates VLDL-TG hydrolysis by reducing the association of HL with HDL. Therefore, HDL controls the hydrolysis of VLDL by affecting the interlipoprotein association of HL. Lipoprotein electrostatic properties regulate lipase association and are an important regulator of the binding and activity of lipolytic enzymes.

  18. Design of a novel chimeric tissue plasminogen activator with favorable Vampire bat plasminogen activator properties.

    PubMed

    Kazemali, MohammadReza; Majidzadeh-A, Keivan; Sardari, Soroush; Saadatirad, Amir Hossein; Khalaj, Vahid; Zarei, Najmeh; Barkhordari, Farzaneh; Adeli, Ahmad; Mahboudi, Fereidoun

    2014-12-01

    Fibrinolytic agents are widely used in treatment of the thromboembolic disorders. The new generations like recombinant tissue plasminogen activator (t-PA, alteplase) are not showing promising results in clinical practice in spite of displaying specific binding to fibrin in vitro. Vampire bat plasminogen activator (b-PA) is a plasminogen activator with higher fibrin affinity and specificity in comparison to t-PA resulting in reduced probability of hemorrhage. b-PA is also resistant to plasminogen activator inhibitor-1 (PAI-1) showing higher half-life compared to other variants of t-PA. However, its non-human origin was a driving force to design a human t-PA with favorable properties of b-PA. In the present study, we designed a chimeric t-PA with desirable b-PA properties and this new molecule was called as CT-b. The construct was prepared through kringle 2 domain removal and replacement of t-PA finger domain with b-PA one. In addition, the KHRR sequence at the initial part of protease domain was replaced by four alanine residues. The novel construct was integrated in Pichia pastoris genome by electroporation. Catalytic activity was investigated in the presence and absence of fibrin. The purified protein was analyzed by western blot. Fibrin binding and PAI resistance assays were also conducted. The activity of the recombinant protein in the presence of fibrin was 1560 times more than its activity in the absence of fibrin, showing its higher specificity to fibrin. The fibrin binding of CT-b was 1.2 fold more than t-PA. In addition, it was inhibited by PAI enzyme 44% less than t-PA. Although the presented data demonstrate a promising in vitro activity, more in vivo studies are needed to confirm the therapeutic advantage of this novel plasminogen activator.

  19. Design of a novel chimeric tissue plasminogen activator with favorable Vampire bat plasminogen activator properties.

    PubMed

    Kazemali, MohammadReza; Majidzadeh-A, Keivan; Sardari, Soroush; Saadatirad, Amir Hossein; Khalaj, Vahid; Zarei, Najmeh; Barkhordari, Farzaneh; Adeli, Ahmad; Mahboudi, Fereidoun

    2014-12-01

    Fibrinolytic agents are widely used in treatment of the thromboembolic disorders. The new generations like recombinant tissue plasminogen activator (t-PA, alteplase) are not showing promising results in clinical practice in spite of displaying specific binding to fibrin in vitro. Vampire bat plasminogen activator (b-PA) is a plasminogen activator with higher fibrin affinity and specificity in comparison to t-PA resulting in reduced probability of hemorrhage. b-PA is also resistant to plasminogen activator inhibitor-1 (PAI-1) showing higher half-life compared to other variants of t-PA. However, its non-human origin was a driving force to design a human t-PA with favorable properties of b-PA. In the present study, we designed a chimeric t-PA with desirable b-PA properties and this new molecule was called as CT-b. The construct was prepared through kringle 2 domain removal and replacement of t-PA finger domain with b-PA one. In addition, the KHRR sequence at the initial part of protease domain was replaced by four alanine residues. The novel construct was integrated in Pichia pastoris genome by electroporation. Catalytic activity was investigated in the presence and absence of fibrin. The purified protein was analyzed by western blot. Fibrin binding and PAI resistance assays were also conducted. The activity of the recombinant protein in the presence of fibrin was 1560 times more than its activity in the absence of fibrin, showing its higher specificity to fibrin. The fibrin binding of CT-b was 1.2 fold more than t-PA. In addition, it was inhibited by PAI enzyme 44% less than t-PA. Although the presented data demonstrate a promising in vitro activity, more in vivo studies are needed to confirm the therapeutic advantage of this novel plasminogen activator. PMID:25442953

  20. Chemical properties and antioxidant and antimicrobial activities of Slovenian propolis.

    PubMed

    Mavri, Ana; Abramovič, Helena; Polak, Tomaž; Bertoncelj, Jasna; Jamnik, Polona; Smole Možina, Sonja; Jeršek, Barbara

    2012-08-01

    The chemical composition as well as the antioxidant and antimicrobial activities of two EtOH extracts of propolis (PEEs) from Slovenia were determined. EtOH was used as extracting solvent at 70 and 96%, providing the extracts PEE70 and PEE96, respectively. The extraction with 70% EtOH was more efficient than that with 96% EtOH, as the PEE70 was richer in total phenolic compounds than the PEE96. The Slovenian propolis was characterized by different phenolic acids and flavonoids. The PEE96 was slightly richer in three specific compounds, i.e., caffeic acid, ferulic acid, and luteolin, while all other substances detected showed higher contents in the PEE70. The PEE70 showed a stronger reducing power and ability to scavenge free radicals and metal ions than the PEE96. Both PEEs were in the main more effective against Gram-positive bacteria than against fungi and Gram-negative bacteria like Salmonella and Escherichia coli, with the exception of Campylobacter. The PEE96 decreased the intracellular oxidation in Saccharomyces cerevisiae in a dose-dependent manner. The antimicrobial activities and antioxidant properties were related to the total phenolic contents. The two PEEs have the potential for use as natural antimicrobial and antioxidant additives in foods.

  1. Spatially Offset Active Galactic Nuclei. I. Selection and Spectroscopic Properties

    NASA Astrophysics Data System (ADS)

    Barrows, R. Scott; Comerford, Julia M.; Greene, Jenny E.; Pooley, David

    2016-09-01

    We present a sample of 18 optically selected and X-ray-detected spatially offset active galactic nuclei (AGNs) from the Sloan Digital Sky Survey (SDSS). In nine systems, the X-ray active galactic nucleus (AGN) is spatially offset from the galactic stellar core that is located within the 3″ diameter SDSS spectroscopic fiber. In 11 systems, the X-ray AGN is spatially offset from a stellar core that is located outside the fiber, with an overlap of two. To build the sample, we cross-matched Type II AGNs selected from the SDSS galaxy catalog with archival Chandra imaging and employed our custom astrometric and registration procedure. The projected angular (physical) offsets span a range of 0.″6 (0.8 kpc) to 17.″4 (19.4 kpc), with a median value of 2.″7 (4.6 kpc). The offset nature of an AGN is an unambiguous signature of a galaxy merger, and these systems can be used to study the properties of AGNs in galaxy mergers without the biases introduced by morphological merger selection techniques. In this paper (Paper I), we use our sample to assess the kinematics of AGN photoionized gas in galaxy mergers. We find that spectroscopic offset AGN selection may be up to {89}-16+7% incomplete due to small projected velocity offsets. We also find that the magnitude of the velocity offsets are generally larger than expected if our spatial selection introduces a bias toward face-on orbits, suggesting the presence of complex kinematics in the emission line gas of AGNs in galaxy mergers.

  2. Plant polyphenols: chemical properties, biological activities, and synthesis.

    PubMed

    Quideau, Stéphane; Deffieux, Denis; Douat-Casassus, Céline; Pouységu, Laurent

    2011-01-17

    Eating five servings of fruits and vegetables per day! This is what is highly recommended and heavily advertised nowadays to the general public to stay fit and healthy! Drinking green tea on a regular basis, eating chocolate from time to time, as well as savoring a couple of glasses of red wine per day have been claimed to increase life expectancy even further! Why? The answer is in fact still under scientific scrutiny, but a particular class of compounds naturally occurring in fruits and vegetables is considered to be crucial for the expression of such human health benefits: the polyphenols! What are these plant products really? What are their physicochemical properties? How do they express their biological activity? Are they really valuable for disease prevention? Can they be used to develop new pharmaceutical drugs? What recent progress has been made toward their preparation by organic synthesis? This Review gives answers from a chemical perspective, summarizes the state of the art, and highlights the most significant advances in the field of polyphenol research.

  3. Optical Properties of Anisotropic Polycrystalline Ce+3 activated LSO

    PubMed Central

    Roy, Sudesna; Lingertat, Helmut; Brecher, Charles; Sarin, Vinod

    2012-01-01

    Polycrystalline cerium activated lutetium oxyorthosilicate (LSO:Ce) is highly desirable technique to make cost effective and highly reproducible radiation detectors for medical imaging. In this article methods to improve transparency in polycrystalline LSO:Ce were explored. Two commercially available powders of different particulate sizes (average particle size 30 and 1500 nm) were evaluated for producing dense LSO:Ce by pressure assisted densification routes, such as hot pressing and hot isostatic pressing. Consolidation of the powders at optimum conditions produced three polycrystalline ceramics with average grain sizes of 500 nm, 700 and 2000 nm. Microstructural evolution studies showed that for grain sizes larger than 1 µm, anisotropy in thermal expansion coefficient and elastic constants of LSO, resulted in residual stress at grain boundaries and triple points that led to intragranular microcracking. However, reducing the grain size below 1 µm effectively avoids microcracking, leading to more favorable optical properties. The optical scattering profiles generated by a Stover scatterometer, measured by a He-Ne laser of wavelength 633 nm, showed that by reducing the grain size from 2 µm to 500 nm, the in-line transmission increased by a factor of 103. Although these values were encouraging and showed that small changes in grain size could increase transmission by almost 3 orders of magnitude, even smaller grain sizes need to be achieved in order to get truly transparent material with high in-line transmission. PMID:23505329

  4. Characterization and metal sorptive properties of oxidized active carbon.

    PubMed

    Strelko, Vladimir; Malik, Danish J

    2002-06-01

    A commercial activated carbon Chemviron F 400 has been oxidized using nitric acid in order to introduce a variety of acidic surface functional groups. Both unoxidized and oxidized carbon samples were characterized using nitrogen porosimetry, elemental analysis, pH titration, Boehm's titration, and electrophoretic mobility measurements. Results show that oxidation treatment reduced surface area and pore volume. However, the carbon surface acquires an acidic character with carboxylic groups being the dominant surface functional groups. The modified sample displays cation-exchange properties over a wide range of pH values and exhibits polyfunctional nature. Both carbon samples were challenged for the removal of transition metals such as copper(II), nickel(II), cobalt(II), zinc(II), and manganese(II). The affinity series Mn2+Zn2+ has been found to coincide with the general stability sequence of metal complexes (the Irving-Williams series). The higher preference displayed by carbons toward copper(II) is a consequence of the fact that copper(II) often forms distorted and more stable octahedral complexes. PMID:16290653

  5. Plant polyphenols: chemical properties, biological activities, and synthesis.

    PubMed

    Quideau, Stéphane; Deffieux, Denis; Douat-Casassus, Céline; Pouységu, Laurent

    2011-01-17

    Eating five servings of fruits and vegetables per day! This is what is highly recommended and heavily advertised nowadays to the general public to stay fit and healthy! Drinking green tea on a regular basis, eating chocolate from time to time, as well as savoring a couple of glasses of red wine per day have been claimed to increase life expectancy even further! Why? The answer is in fact still under scientific scrutiny, but a particular class of compounds naturally occurring in fruits and vegetables is considered to be crucial for the expression of such human health benefits: the polyphenols! What are these plant products really? What are their physicochemical properties? How do they express their biological activity? Are they really valuable for disease prevention? Can they be used to develop new pharmaceutical drugs? What recent progress has been made toward their preparation by organic synthesis? This Review gives answers from a chemical perspective, summarizes the state of the art, and highlights the most significant advances in the field of polyphenol research. PMID:21226137

  6. Dynamic properties of biologically active synthetic heparin-like hexasaccharides.

    PubMed

    Angulo, Jesús; Hricovíni, Milos; Gairi, Margarida; Guerrini, Marco; de Paz, José Luis; Ojeda, Rafael; Martín-Lomas, Manuel; Nieto, Pedro M

    2005-10-01

    A complete study of the dynamics of two synthetic heparin-like hexasaccharides, D-GlcNHSO3-6-SO4-alpha-(1-->4)-L-IdoA-2-SO4-alpha-(1-->4)-D-GlcNHSO3-6-SO4-alpha-(1-->4)-L-IdoA-2-SO4-alpha-(1-->4)-D-GlcNHSO3-6-SO4-alpha-(1-->4)-L-IdoA-2-SO4-alpha-1-->iPr (1) and -->4)-L-IdoA-2-SO4-alpha-(1-->4)-D-GlcNHAc-6-SO4-alpha-(1-->4)-L-IdoA-alpha-(1-->4)-D-GlcNHSO3-alpha-(1-->4)-L-IdoA-2-SO4-alpha-1-->iPr (2), has been performed using 13C-nuclear magnetic resonance (NMR) relaxation parameters, T1, T2, and heteronuclear nuclear Overhauser effect (NOEs). Compound 1 is constituted from sequences corresponding to the major polysaccharide heparin region, while compound 2 contains a sequence never found in natural heparin. They differ from each other only in sulphation patterns, and are capable of stimulating fibroblast growth factors (FGFs)-1 induced mitogenesis. Both oligosaccharides exhibit a remarkable anisotropic overall motion in solution as revealed by their anisotropic ratios (tau /tau||), 4.0 and 3.0 respectively. This is a characteristic behaviour of natural glycosaminoglycans (GAG) which has also been observed for the antithrombin (AT) binding pentasaccharide D-GlcNHSO3-6-SO4-alpha-(1-->4)-D-GlcA-beta-(1-->4)-D-GlcNHSO3-(3,6-SO4)-alpha-(1-->4)-L-IdoA-2-SO4-alpha-(1-->4)-D-GlcNHSO3-6-SO4-alpha-1-->Me (3) (Hricovíni, M., Guerrini, M., Torri, G., Piani, S., and Ungarelli, F. (1995) Conformational analysis of heparin epoxide in aqueous solution. An NMR relaxation study. Carbohydr. Res., 277, 11-23). The motional properties observed for 1 and 2 provide additional support to the suitability of these compounds as heparin models in agreement with previous structural (de Paz, J.L., Angulo, J., Lassaletta, J.M., Nieto, P.M., Redondo-Horcajo, M., Lozano, R.M., Jiménez-Gallego, G., and Martín-Lomas, M. (2001) The activation of fibroblast growth factors by heparin: synthesis, structure and biological activity of heparin-like oligosaccharides. Chembiochem, 2, 673-685; Ojeda, R

  7. Dynamic properties of biologically active synthetic heparin-like hexasaccharides.

    PubMed

    Angulo, Jesús; Hricovíni, Milos; Gairi, Margarida; Guerrini, Marco; de Paz, José Luis; Ojeda, Rafael; Martín-Lomas, Manuel; Nieto, Pedro M

    2005-10-01

    A complete study of the dynamics of two synthetic heparin-like hexasaccharides, D-GlcNHSO3-6-SO4-alpha-(1-->4)-L-IdoA-2-SO4-alpha-(1-->4)-D-GlcNHSO3-6-SO4-alpha-(1-->4)-L-IdoA-2-SO4-alpha-(1-->4)-D-GlcNHSO3-6-SO4-alpha-(1-->4)-L-IdoA-2-SO4-alpha-1-->iPr (1) and -->4)-L-IdoA-2-SO4-alpha-(1-->4)-D-GlcNHAc-6-SO4-alpha-(1-->4)-L-IdoA-alpha-(1-->4)-D-GlcNHSO3-alpha-(1-->4)-L-IdoA-2-SO4-alpha-1-->iPr (2), has been performed using 13C-nuclear magnetic resonance (NMR) relaxation parameters, T1, T2, and heteronuclear nuclear Overhauser effect (NOEs). Compound 1 is constituted from sequences corresponding to the major polysaccharide heparin region, while compound 2 contains a sequence never found in natural heparin. They differ from each other only in sulphation patterns, and are capable of stimulating fibroblast growth factors (FGFs)-1 induced mitogenesis. Both oligosaccharides exhibit a remarkable anisotropic overall motion in solution as revealed by their anisotropic ratios (tau /tau||), 4.0 and 3.0 respectively. This is a characteristic behaviour of natural glycosaminoglycans (GAG) which has also been observed for the antithrombin (AT) binding pentasaccharide D-GlcNHSO3-6-SO4-alpha-(1-->4)-D-GlcA-beta-(1-->4)-D-GlcNHSO3-(3,6-SO4)-alpha-(1-->4)-L-IdoA-2-SO4-alpha-(1-->4)-D-GlcNHSO3-6-SO4-alpha-1-->Me (3) (Hricovíni, M., Guerrini, M., Torri, G., Piani, S., and Ungarelli, F. (1995) Conformational analysis of heparin epoxide in aqueous solution. An NMR relaxation study. Carbohydr. Res., 277, 11-23). The motional properties observed for 1 and 2 provide additional support to the suitability of these compounds as heparin models in agreement with previous structural (de Paz, J.L., Angulo, J., Lassaletta, J.M., Nieto, P.M., Redondo-Horcajo, M., Lozano, R.M., Jiménez-Gallego, G., and Martín-Lomas, M. (2001) The activation of fibroblast growth factors by heparin: synthesis, structure and biological activity of heparin-like oligosaccharides. Chembiochem, 2, 673-685; Ojeda, R

  8. Surface active properties of chitosan and its derivatives.

    PubMed

    Elsabee, Maher Z; Morsi, Rania Elsayed; Al-Sabagh, A M

    2009-11-01

    This review discusses the definition of surface active agents and specifically natural polymeric surface active agents. Chitosan by itself was found to have weak surface activity since it has no hydrophobic segments. Chemical modifications of chitosan could improve such surface activity. This is achieved by introducing hydrophobic substituents in its glucosidic group. Several examples of chitosan derivatives with surfactant activity have been surveyed. The surface active polymers form micelles and aggregates which have enormous importance in the entrapment of water-insoluble drugs and consequently applications in the controlled drug delivery and many biomedical fields. Chitosan also interacts with several substrates by electrostatic and hydrophobic interactions with considerable biomedical applications.

  9. Regulation of Ribulose-1,5-Bisphosphate Carboxylase Activity in Alocasia macrorrhiza in Response to Step Changes in Irradiance 1

    PubMed Central

    Seemann, Jeffrey R.; Kirschbaum, Miko U. F.; Sharkey, Thomas D.; Pearcy, Robert W.

    1988-01-01

    The regulation of ribulose-1,5-bisphosphate (RuBP) carboxylase (Rubisco) activity and pool sizes of RuBP and P-glycerate were examined in the tropical understory species Alocasia macrorrhiza following step changes in photon flux density (PFD). Previous gas exchange analysis of this species following a step increase in PFD from 10 to 500 micromoles quanta per square meter per second suggested that the increase in photosynthetic rate was limited by the rate of increase of Rubisco activity for the first 5 to 10 minutes. We demonstrate here that the increase in photosynthetic rate was correlated with an increase in both the activation state of Rubisco and the total kcat (fully activated specific activity) of the enzyme. Evidence presented here suggests that a change in the pool size of the naturally occurring tight binding inhibitor of Rubisco activity, 2-carboxyarabinitol 1-phosphate, was responsible for the PFD-dependent change in the total kcat of the enzyme. RuBP pool size transiently increased after the increase in PFD, indicating that photosynthesis was limited by the capacity for carboxylation. After 5 to 10 minutes, RuBP pool size was again similar to the pool size at low PFD, presumably because of the increased activity of Rubisco. Following a step decrease in PFD from 500 to 10 micromoles quanta per square meter per second, Rubisco activity declined but at a much slower rate than it had increased in response to a step increase in PFD. This slower rate of activity decline than increase was apparently due to the slower rate of 2-carboxyarabinitol 1-phosphate synthesis than degradation and, to a lesser degree, to slower deactivation than activation. RuBP pool size initially declined following the decrease in PFD, indicating that RuBP regeneration was limiting photosynthesis. As Rubisco activity decreased, RuBP slowly increased to its original level at high PFD. The slow rate of activity loss by Rubisco in this species suggests a biochemical basis for the

  10. Phytoplankton carbon fixation gene (RuBisCO) transcripts and air-sea CO2 flux in the Mississippi River plume

    SciTech Connect

    John, David E.; Wang, Zhaohui A.; Liu, Xuewu; Byrne, Robert H.; Corredor, Jorge E.; López, José M.; Cabrera, Alvaro; Bronk, Deborah A.; Tabita, F. Robert; Paul, John H.

    2007-08-30

    River plumes deliver large quantities of nutrients to oligotrophic oceans, often resulting in significant CO2 drawdown. To determine the relationship between expression of the major gene in carbon fixation (large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, RuBisCO) and CO2 dynamics, we evaluated rbcL mRNA abundance using novel quantitative PCR assays, phytoplankton cell analyses, photophysiological parameters, and pCO2 in and around the Mississippi River plume (MRP) in the Gulf of Mexico. Lower salinity (30–32) stations were dominated by rbcL mRNA concentrations from heterokonts, such as diatoms and pelagophytes, which were at least an order of magnitude greater than haptophytes, alpha-Synechococcus or high-light Prochlorococcus. However, rbcL transcript abundances were similar among these groups at oligotrophic stations (salinity 34–36). Diatom cell counts and heterokont rbcL RNA showed a strong negative correlation to seawater pCO2. While Prochlorococcus cells did not exhibit a large difference between low and high pCO2 water, Prochlorococcus rbcL RNA concentrations had a strong positive correlation to pCO2, suggesting a very low level of RuBisCO RNA transcription among Prochlorococcus in the plume waters, possibly due to their relatively poor carbon concentrating mechanisms (CCMs). These results provide molecular evidence that diatom/pelagophyte productivity is largely responsible for the large CO2 drawdown occurring in the MRP, based on the co-occurrence of elevated RuBisCO gene transcript concentrations from this group and reduced seawater pCO2 levels. This may partly be due to efficient CCMs that enable heterokont eukaryotes such as diatoms to continue fixing CO2 in the face of strong CO2 drawdown. Finally, our work represents the first attempt to relate in situ microbial gene expression to contemporaneous CO2 flux

  11. Spontaneous olfactory receptor neuron activity determines follower cell response properties

    PubMed Central

    Joseph, Joby; Dunn, Felice A.; Stopfer, Mark

    2012-01-01

    Noisy or spontaneous activity is common in neural systems and poses a challenge to detecting and discriminating signals. Here we use the locust to answer fundamental questions about noise in the olfactory system: Where does spontaneous activity originate? How is this activity propagated or reduced throughout multiple stages of neural processing? What mechanisms favor the detection of signals despite the presence of spontaneous activity? We found that spontaneous activity long observed in the secondary projection neurons (PNs) originates almost entirely from the primary olfactory receptor neurons (ORNs) rather than from spontaneous circuit interactions in the antennal lobe, and that spontaneous activity in ORNs tonically depolarizes the resting membrane potentials of their target PNs and local neurons (LNs), and indirectly tonically depolarizes tertiary Kenyon cells (KCs). However, because these neurons have different response thresholds, in the absence of odor stimulation, ORNs and PNs display a high spontaneous firing rate but KCs are nearly silent. Finally, we used a simulation of the olfactory network to show that discrimination of signal and noise in the KCs is best when threshold levels are set so that baseline activity in PNs persists. Our results show how the olfactory system benefits from making a signal detection decision after a point of maximal information convergence, e.g., after KCs pool inputs from many PNs. PMID:22357872

  12. Microstructure and surface properties of lignocellulosic-based activated carbons

    NASA Astrophysics Data System (ADS)

    González-García, P.; Centeno, T. A.; Urones-Garrote, E.; Ávila-Brande, D.; Otero-Díaz, L. C.

    2013-01-01

    Low cost activated carbons have been produced via chemical activation, by using KOH at 700 °C, from the bamboo species Guadua Angustifolia and Bambusa Vulgaris Striata and the residues from shells of the fruits of Castanea Sativa and Juglans Regia as carbon precursors. The scanning electron microscopy micrographs show the conservation of the precursor shape in the case of the Guadua Angustifolia and Bambusa Vulgaris Striata activated carbons. Transmission electron microscopy analyses reveal that these materials consist of carbon platelet-like particles with variable length and thickness, formed by highly disordered graphene-like layers with sp2 content ≈ 95% and average mass density of 1.65 g/cm3 (25% below standard graphite). Textural parameters indicate a high porosity development with surface areas ranging from 850 to 1100 m2/g and average pore width centered in the supermicropores range (1.3-1.8 nm). The electrochemical performance of the activated carbons shows specific capacitance values at low current density (1 mA/cm2) as high as 161 F/g in the Juglans Regia activated carbon, as a result of its textural parameters and the presence of pseudocapacitance derived from surface oxygenated acidic groups (mainly quinones and ethers) identified in this activated carbon.

  13. [Impacts of suboptimal temperature and low light intensity on the activities and gene expression of photosynthetic enzymes in cucumber seedling leaves].

    PubMed

    Bi, Huan-Gai; Wang, Mei-Ling; Jiang, Zhen-Sheng; Dong, Xu-Bing; Ai, Xi-Zhen

    2011-11-01

    Taking the cucumber cultivar 'Jinyou 3' as test material, this paper studied the variations of the mRNA expression and activities of ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco), fructose-1, 6-bisphosphatase (FBPase), glyceraldehydes-3-phosphate dehydrogenase (GAPDH), fructose-1, 6-bisphosphate aldolase (FBA), and transketolase (TK) in cucumber seedling leaves under suboptimal temperature and low light intensity (ST+LL). In the treatment of ST+LL, the leaf area and the dry mass per plant decreased remarkably, compared with the control. On the early days of ST+LL treatment, the gene expression of Rubisco rbcL and rbcS, FBPase, GAPDH, FBA, and TK declined markedly, the activities of the enzymes except TK obviously weakened, and the photosynthetic rate (P(n)) decreased rapidly. 3 days later, the gene expression of Rubisco rbcL and rbcS and the initial activity of Rubisco showed a continuous decrease but the decrement was obviously lesser, the total activity of Rubisco and the activities and gene expression of FBPase, GAPDH, FBA, and TK had an increasing trend, and the P(n) ascended simultaneously. When the treating time exceeded 6 days, the gene expression and the activities of Rubisco and FBPase tended to be constant, while those of the other enzymes as well as the P(n) presented a decreasing trend. These results suggested that the decline of the gene expression and activities of the photosynthetic enzymes in cucumber seedlings under suboptimal temperature and low light intensity was the important reason which led to the decrease of P(n). The adaptation of photosynthetic apparatus in cucumber seedlings to suboptimal temperature and low light intensity was related to the activation mechanisms of photosynthetic enzymes.

  14. Biochemical Properties and Possible Roles of Ectophosphatase Activities in Fungi

    PubMed Central

    Freitas-Mesquita, Anita Leocadio; Meyer-Fernandes, José Roberto

    2014-01-01

    Ectophosphatases are surface membrane-bound proteins whose active sites face the extracellular medium. These enzymes have been reported in several microorganisms including a large number of medically relevant fungal species. An effective technique for identifying ectophosphatases is performing phosphatase activity assays using living intact cells. Biochemical characterization of these activities has shown their differential modulation by classical phosphatase inhibitors, divalent metals and pH range. The physiological roles of ectophosphatases are not well established; however, it has been suggested that these enzymes play important roles in nutrition, proliferation, differentiation, adhesion, virulence and infection. Adhesion to host cells is the first step in establishing a fungal infection and ectophosphatases may be one of the first parasite proteins that come into contact with the host cells. Several results indicate that ectophosphatase activities increase the capacity of fungi to adhere to the host cells. In this context, the present review provides an overview of recent discoveries related to the occurrence and possible roles of ectophosphatase activities in fungal cells. PMID:24509700

  15. Autophosphorylation properties of inactive and active JNK2.

    PubMed

    Pimienta, Genaro; Ficarro, Scott B; Gutierrez, Gustavo J; Bhoumik, Anindita; Peters, Eric C; Ronai, Ze'ev; Pascual, Jaime

    2007-07-15

    The c-Jun N-terminal kinases (JNKs) are ubiquitous proteins that phosphorylate their substrates, such as transcription factors, in response to physical stress, cytokines or UV radiation. This leads to changes in gene expression, ensuing either cell cycle progression or apoptosis. Active phospho JNK1 is the main in vivo kinase component of the JNK cascade, whereas JNK2 is presumed not to participate as a kinase during JNK signalling. However, there is evidence that JNK isoforms interact functionally in vivo. Also, a recent chemical genetics investigation has confirmed that JNK transient activation leads to cellular proliferation, whereas a sustained one is pro-apoptotic. Here we investigate the phosphorylation pattern of JNK2, with protein biochemistry tools and tandem mass spectrometry. We choose to focus on JNK2 because of its reported constitutive activity in glioma cells. Our results indicate that purified JNK2 from transfected nonstressed 293T cells is a mixture of the mono-sites pThr183 and pTyr185 of its activation loop and of pThr386 along its unique C-terminal region. Upon UV stimulation, its phosphorylation stoichiometry is upregulated on the activation loop, generating a mixture of mono-pTyr185 and the expected dual-pThr183/pTyr185 species, with the pThr386 specie present but unaltered respect to the basal conditions.

  16. Fungal Polysaccharides: Biological Activity Beyond the Usual Structural Properties

    PubMed Central

    Rodrigues, Marcio L.; Nimrichter, Leonardo; Cordero, Radames J. B.; Casadevall, Arturo

    2011-01-01

    Studies on structure and function of polysaccharides in biological systems classically involve sequence and compositional analyses, anomeric configuration, type of glycosidic linkage, and presence of substituents. Recent studies, however, indicates that other structural parameters, so far little explored, can directly influence the biological activity of microbial polysaccharides. Among these parameters, we highlight the molecular dimensions of Cryptococcus neoformans polysaccharides, which appear to be inversely correlated with their immunobiological activity. These recent observations raise new concepts about the structure and function of polysaccharides, which stimulates the design of new experimental approaches and suggests previously unknown applications. PMID:21886639

  17. Rubisco small subunit, chlorophyll a/b-binding protein and sucrose:fructan-6-fructosyl transferase gene expression and sugar status in single barley leaf cells in situ. Cell type specificity and induction by light.

    PubMed

    Lu, Chungui; Koroleva, Olga A; Farrar, John F; Gallagher, Joe; Pollock, Chris J; Tomos, A Deri

    2002-11-01

    We describe a highly efficient two-step single-cell reverse transcriptase-polymerase chain reaction technique for analyzing gene expression at the single-cell level. Good reproducibility and a linear dose response indicated that the technique has high specificity and sensitivity for detection and quantification of rare RNA. Actin could be used as an internal standard. The expression of message for Rubisco small subunit (RbcS), chlorophyll a/b-binding protein (Cab), sucrose (Suc):fructan-6-fructosyl transferase (6-SFT), and Actin were measured in individual photosynthetic cells of the barley (Hordeum vulgare) leaf. Only Actin was found in the non-photosynthetic epidermal cells. Cab, RbcS, and 6-SFT genes were expressed at a low level in mesophyll and parenchymatous bundle sheath (BS) cells when sampled from plants held in dark for 40 h. Expression increased considerably after illumination. The amount of 6-SFT, Cab, and RbcS transcript increased more in mesophyll cells than in the parenchymatous BS cells. The difference may be caused by different chloroplast structure and posttranscriptional control in mesophyll and BS cells. When similar single-cell samples were assayed for Suc, glucose, and fructan, there was high correlation between 6-SFT gene expression and Suc and glucose concentrations. This is consistent with Suc concentration being the trigger for transcription. Together with earlier demonstrations that the mesophyll cells have a higher sugar threshold for fructan polymerization, our data may indicate separate control of transcription and enzyme activity. Values for the sugar concentrations of the individual cell types are reported.

  18. Surface-active properties of humic and sulfochlorohumic acids

    SciTech Connect

    Ryabova, I.N.; Mustafina, G.A.; Akkulova, Z.G.; Satymbaeva, A.S.

    2009-10-15

    The surface tension of alkaline solutions of humic acids and their sulfochloroderivatives, which are synthesized by sulfonation of chlorohumic acids isolated from coal chlorinated by the electrochemical method, is investigated. It is established that humic compounds possess weak surface activity. Basic adsorption parameters are calculated.

  19. Level of independence of motor unit properties from neuromuscular activity.

    PubMed

    Pierotti, D J; Roy, R R; Hodgson, J A; Edgerton, V R

    1994-11-01

    Neuromuscular activity was eliminated in the tibialis anterior muscle of adult cats for 6 months by spinal isolation (SI), i.e., complete spinal cord transections at T-12-13 and at L-7-S-1, plus bilateral dorsal rhizotomy between the two transection sites. One motor unit from each muscle was isolated using ventral root teasing procedures and physiologically tested. The fibers belonging to each motor unit were visualized in PAS-stained sections by the loss of glycogen following prolonged repetitive stimulation. Qualitatively, the normal enzymatic interrelationships among fibers identified by myosin heavy chain composition were unchanged by SI. Generally, each motor unit from SI cats were of a single myosin immunohistochemical type. The same physiological motor unit types that typify control muscles were found in SI cats. In SI compared to control cats, there was approximately a 10% increase in the number of muscle fibers expressing fast myosin. Mean fiber activity levels of ATPase and SDH for a given fiber type (based on MHC antibody reactions) decreased by approximately 10% and 25%, whereas GPD activity increased approximately 35%. It is concluded that differential levels or patterns of activity are not essential to maintain the range of histochemical and physiological motor unit types found in the tibialis anterior of normal adult cats.

  20. Scintillation Properties of Eu2+-Activated Barium Fluoroiodide

    SciTech Connect

    Gundiah, Gautam; Bourret-Courchesne, Edith; Bizarri, Gregory; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew; Moses, William W.; Derenzo, Stephen E.

    2009-11-18

    The scintillation properties of powders and single-crystals of BaFI doped with Eu2+ are presented. Single crystals were grown by the vertical Bridgman technique. Under optical and X-ray excitation, the samples exhibit a narrow E2+ 5d-4f transition emission centered at 405 nm. The scintillation light output is estimated to be 55,000+-5,000 photons/MeV at 662 keV with 85percent of the light decaying within 600 ns. An energyresolution of 8.5percent full width at half maximum (FWHM) has been achieved using this scintillator for 662 keV excitation (137Cs source) at room temperature.

  1. Biological activities and medicinal properties of Cajanus cajan (L) Millsp.

    PubMed

    Pal, Dilipkumar; Mishra, Pragya; Sachan, Neetu; Ghosh, Ashoke K

    2011-10-01

    Cajanus cajan (L) Millsp. (Sanskrit: Adhaki, Hindi: Arhar, English: Pigeon pea, Bengali: Tur) (family: Fabaceae) is the most important grain legume crop of rain-fed agriculture in semi-arid tropics. It is both a food crop and a cover/forage crop with high levels of proteins and important amino acids like methionine, lysine and tryptophan. During the last few decades extensive studies have been carried out regarding the chemistry of C. cajan and considerable progress has been achieved regarding its biological activities and medicinal applications. This review article gives an overview on the biological activities of the compounds isolated, pharmacological actions and clinical studies of C. cajan extracts apart from its general details.

  2. Cytotoxic activity and DNA-binding properties of isoeuxanthone derivatives.

    PubMed

    Wang, Hui Fang; Yan, Hong; Gao, Xianghua; Niu, Baolong; Guo, Ruijie; Wei, Liqiao; Xu, Bingshe; Tang, Ning

    2014-01-01

    In this study, the interactions of different groups substituted isoeuxanthone derivatives with calf thymus DNA (ct DNA) were investigated by spectrophotometric methods and viscosity measurements. Results indicated that the xanthone derivatives could intercalate into the DNA base pairs by the plane of xanthone ring and the various substituents may influence the binding affinity with DNA according to the calculated quenching constant values. Furthermore, two tumor cell lines including the human cervical cancer cell line (HeLa) and human hepatocellular liver carcinoma cell line (HepG2) were used to evaluate the cytotoxic activities of xanthone derivatives by acid phosphatase assay. Analyses showed that the oxiranylmethoxy substituted xanthone exhibited more effective cytotoxic activity against the cancer cells than the other substituted xanthones. The effects on the inhibition of tumor cells in vitro agreed with the studies of DNA-binding. PMID:24583780

  3. 24 CFR 570.513 - Lump sum drawdown for financing of property rehabilitation activities.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DEVELOPMENT BLOCK GRANTS Grant Administration § 570.513 Lump sum drawdown for financing of property... 24 Housing and Urban Development 3 2010-04-01 2010-04-01 false Lump sum drawdown for financing of property rehabilitation activities. 570.513 Section 570.513 Housing and Urban Development...

  4. PREDICTING THE ADSORPTION CAPACITY OF ACTIVATED CARBON FOR ORGANIC CONTAMINANTS FROM ADSORBENT AND ADSORBATE PROPERTIES

    EPA Science Inventory

    A quantitative structure-property relationship (QSPR) was developed and combined with the Polanyi-Dubinin-Manes model to predict adsorption isotherms of emerging contaminants on activated carbons with a wide range of physico-chemical properties. Affinity coefficients (βl

  5. Synthesis, antiproliferative activity and molecular properties predictions of galloyl derivatives.

    PubMed

    da Silva, Marciane Maximo; Comin, Marina; Duarte, Thiago Santos; Foglio, Mary Ann; de Carvalho, João Ernesto; do Vieira, Maria Carmo; Formagio, Anelise Samara Nazari

    2015-03-25

    The present study was designed to investigate the in vitro antiproliferative activity against ten human cancer cell lines of a series of galloyl derivatives bearing substituted-1,3,4-oxadiazole and carbohydrazide moieties. The compounds were also assessed in an in silico study of the absorption, distribution, metabolism and excretion (ADME) in the human body using Lipinski's parameters, the topological polar surface area (TPSA) and percentage of absorption (%ABS). In general, the introduction of N'-(substituted)-arylidene galloyl hydrazides 4-8 showed a moderate antitumor activity, while the 2-methylthio- and 2-thioxo-1,3,4-oxadiazol-5-yl derivatives 9 and 10 led to increased inhibition of cancer cell proliferation. The precursor compound methyl gallate 2 and the intermediary galloyl hydrazide 3 showed greater antiproliferative activity with GI50 values < 5.54 µM against all human tumor cell lines tested. A higher inhibition effect against ovarian cancer (OVCAR-3) (GI50 = 0.05-5.98 µM) was also shown, with compounds 2, 3, 9 and 10 with GI50 ≤ 0.89 µM standing out in this respect. The in silico study revealed that the compounds showed good intestinal absorption.

  6. Motor activity and muscle properties in the hemidecerebellate cat.

    PubMed

    Stenvers, J W; Eerbeek, O; de Jong, J M; Meijer, A E

    1983-09-01

    Luciani's ipsilaterally acting 'trophic' cerebellar influence on striated muscle was reinvestigated in hemidecerebellate preparations of varying extent. Cats with hindlimb postural asymmetries for 4 or more days after the lesion developed a bilateral reduction of maximum tetanic tension and increased twitch/tetanus ratios of soleus. In addition, soleus on the side of the lesion lost force and weight, showed decreased twitch contraction and half-relaxation times, elevated myosin ATPase activity in part of its fibres, occasional fibre necrosis and a few snake coils. Protracted postural asymmetry occurred only if complete hemicerebellectomy included ablation of the lateral vestibular nucleus and extended for at least 3.0 mm across the midline into the contralateral vermal and intermediate cortex, especially of Larsell's lobuli IV and V. Most simply, the cerebellar effect on muscle is explained as the result of altered motoneuronal activation patterns. Comparison of the experimental soleus changes with Holmes's clinical findings in cases of cerebellar injury suggests that muscle itself participates in experimental and human cerebellar asthenia.

  7. Aerosol activation properties and CCN closure during TCAP

    NASA Astrophysics Data System (ADS)

    Mei, F.; Tomlinson, J. M.; Shilling, J. E.; Wilson, J. M.; Zelenyuk, A.; Chand, D.; Comstock, J. M.; Hubbe, J.; Berg, L. K.; Schmid, B.

    2013-12-01

    The indirect effects of atmospheric aerosols currently remain the most uncertain components in forcing of climate change over the industrial period (IPCC, 2007). This large uncertainty is partially due to our incomplete understanding of the ability of particles to form cloud droplets under atmospherically relevant supersaturation. In addition, there is a large uncertainty in the aerosol optical depth (AOD) simulated by climate models near the North American coast and a wide variety in the types of clouds are observed over this region. The goal of the US Department of Energy Two Column Aerosol Project (TCAP) is to understand the processes responsible for producing and maintaining aerosol distributions and associated radiative and cloud forcing off the coast of North America. During the TCAP study, aerosol total number concentration, cloud condensation nuclei (CCN) spectra and aerosol chemical composition were in-situ measured from the DOE Gulfstream 1 (G-1) research aircraft during two Intensive Operations Periods (IOPs), one conducted in July 2012 and the other in February 2013. An overall aerosol size distribution was achieved by merging the observations from several instruments, including Ultra High Sensitivity Aerosol Spectrometer - Airborne (UHSAS-A, DMT), Passive Cavity Aerosol Spectrometer Probe (PCASP-200, DMT), and Cloud Aerosol Spectrometer (CAS, DMT). Aerosol chemical composition was characterized using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS, Aerodyne Inc.) and single particle mass spectrometer, mini-SPLAT. Based on the aerosol size distribution, CCN number concentration (characterized by a DMT dual column CCN counter with a range from 0.1% to 0.4%), and chemical composition, a CCN closure was obtained. The sensitivity of CCN closure to organic hygroscopicity was investigated. The differences in aerosol/CCN properties between two columns, and between two phases, will be discussed.

  8. Amplifying properties of heavily erbium-doped active fibres

    SciTech Connect

    Plotskii, A Yu; Kurkov, Andrei S; Yashkov, M Yu; Bubnov, M M; Likhachev, M E; Sysolyatin, A A; Dianov, Evgenii M; Gur'yanov, A N

    2005-06-30

    The relative concentration of erbium ions undergoing nonradiative relaxation from the metastable to the ground level is measured in aluminosilicate glass fibres doped with erbium ions at concentration between 3x10{sup 18} and 10{sup 20} cm{sup -3}. The dependence of the fraction of such ions on the Er{sup 3+} concentration is determined for fibres containing different amounts of aluminium oxide in a core. It is shown that the fraction of erbium ions not involved in amplification substantially decreases with increasing the Al{sub 2}O{sub 3} concentration. It is found that clustering leads to a considerable decrease in the gain in heavily Er{sup 3+}-doped active fibres. The dependence of the quantum efficiency of a fibre amplifier on the erbium ion concentration is obtained based on the measurements performed. This dependence can be used for optimising the parameters of erbium-doped fibre amplifiers. (fibres. integrated-optic waveguides)

  9. Antioxidant, Antimicrobial Activity and Medicinal Properties of Grewia asiatica L.

    PubMed

    Shukla, Ritu; Sharma, Dinesh C; Baig, Mohammad H; Bano, Shabana; Roy, Sudeep; Provazník, Ivo; Kamal, Mohammad A

    2016-01-01

    Since ancient time, India is a well known subcontinent for medicinal plants where diversity of plants is known for the treatment of many human disorders. Grewia asiatica is a dicot shrub belonging to the Grewioideae family and well known for its medicinally important fruit commonly called Falsa. G. asiatica, a seasonal summer plant is distributed in the forest of central India, south India, also available in northern plains and western Himalaya up to the height of 3000 ft. Fruits of G. asiatica are traditionally used as a cooling agent, refreshing drink, anti-inflammatory agent and for the treatment of some urological disorders. Recent advancement of Falsa researches concluded its antimicrobial and anti-diabetic activity. Since ancient time medicinal plants are traditionally used for the treatment of different diseases G. asiatica fruit is the edible and tasty part of the plant, now considered as a valuable source of unique natural product for the development of medicines which are used in different disease conditions like anti-diabetic, anti-inflammatory, anti-cancerous and antimicrobial. Now a days, G. asiatica is being used in different Ayurvedic formulation for the cure of different types of diseases. Different pharmacological investigations reveal the presence of phenols, saponnins, flavonoids and tannins compound in the fruits. Present review highlights the phytopharmacological and different traditional use of G. asiatica which is mentioned in ancient Ayurvedic texts. This review stimulates the researchers and scientists for further research on G. asiatica. PMID:26516779

  10. Optical Properties of Active Regions in Terahertz Quantum Cascade Lasers

    NASA Astrophysics Data System (ADS)

    Dyksik, M.; Motyka, M.; Rudno-Rudziński, W.; Sęk, G.; Misiewicz, J.; Pucicki, D.; Kosiel, K.; Sankowska, I.; Kubacka-Traczyk, J.; Bugajski, M.

    2016-07-01

    In this work, AlGaAs/GaAs superlattice, with layers' sequence and compositions imitating the active and injector regions of a quantum cascade laser designed for emission in the terahertz spectral range, was investigated. Three independent absorption-like optical spectroscopy techniques were employed in order to study the band structure of the minibands formed within the conduction band. Photoreflectance measurements provided information about interband transitions in the investigated system. Common transmission spectra revealed, in the target range of intraband transitions, mainly a number of lines associated with the phonon-related processes, including two-phonon absorption. In contrast, differential transmittance realized by means of Fourier-transform spectroscopy was utilized to probe the confined states of the conduction band. The obtained energy separation between the second and third confined electron levels, expected to be predominantly contributing to the lasing, was found to be ~9 meV. The optical spectroscopy measurements were supported by numerical calculations performed in the effective mass approximation and XRD measurements for layers' width verification. The calculated energy spacings are in a good agreement with the experimental values.

  11. 24 CFR 570.513 - Lump sum drawdown for financing of property rehabilitation activities.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... property rehabilitation activities. 570.513 Section 570.513 Housing and Urban Development Regulations... rehabilitation activities. Subject to the conditions prescribed in this section, recipients may draw funds from the letter of credit in a lump sum to establish a rehabilitation fund in one or more private...

  12. Statistical Properties of Longitudinal Time-Activity Data for Use in Human Exposure Modeling

    EPA Science Inventory

    Understanding the longitudinal properties of the time spent in different locations and activities is important in characterizing human exposure to pollutants. The results of a four-season longitudinal time-activity diary study in eight working adults are presented, with the goal ...

  13. Enhanced leavening properties of baker's yeast by reducing sucrase activity in sweet dough.

    PubMed

    Zhang, Cui-Ying; Lin, Xue; Feng, Bing; Liu, Xiao-Er; Bai, Xiao-Wen; Xu, Jia; Pi, Li; Xiao, Dong-Guang

    2016-07-01

    Leavening ability in sweet dough is required for the commercial applications of baker's yeast. This property depends on many factors, such as glycolytic activity, sucrase activity, and osmotolerance. This study explored the importance of sucrase level on the leavening ability of baker's yeast in sweet dough. Furthermore, the baker's yeast strains with varying sucrase activities were constructed by deleting SUC2, which encodes sucrase or replacing the SUC2 promoter with the VPS8/TEF1 promoter. The results verify that the sucrase activity negatively affects the leavening ability of baker's yeast strains under high-sucrose conditions. Based on a certain level of osmotolerance, sucrase level plays a significant role in the fermentation performance of baker's yeast, and appropriate sucrase activity is an important determinant for the leavening property of baker's yeast in sweet dough. Therefore, modification on sucrase activity is an effective method for improving the leavening properties of baker's yeast in sweet dough. This finding provides guidance for the breeding of industrial baker's yeast strains for sweet dough leavening. The transformants BS1 with deleted SUC2 genetic background provided decreased sucrase activity (a decrease of 39.3 %) and exhibited enhanced leavening property (an increase of 12.4 %). Such a strain could be useful for industrial applications.

  14. Quantitative assessment on soil enzyme activities of heavy metal contaminated soils with various soil properties.

    PubMed

    Xian, Yu; Wang, Meie; Chen, Weiping

    2015-11-01

    Soil enzyme activities are greatly influenced by soil properties and could be significant indicators of heavy metal toxicity in soil for bioavailability assessment. Two groups of experiments were conducted to determine the joint effects of heavy metals and soil properties on soil enzyme activities. Results showed that arylsulfatase was the most sensitive soil enzyme and could be used as an indicator to study the enzymatic toxicity of heavy metals under various soil properties. Soil organic matter (SOM) was the dominant factor affecting the activity of arylsulfatase in soil. A quantitative model was derived to predict the changes of arylsulfatase activity with SOM content. When the soil organic matter content was less than the critical point A (1.05% in our study), the arylsulfatase activity dropped rapidly. When the soil organic matter content was greater than the critical point A, the arylsulfatase activity gradually rose to higher levels showing that instead of harm the soil microbial activities were enhanced. The SOM content needs to be over the critical point B (2.42% in our study) to protect its microbial community from harm due to the severe Pb pollution (500mgkg(-1) in our study). The quantitative model revealed the pattern of variation of enzymatic toxicity due to heavy metals under various SOM contents. The applicability of the model under wider soil properties need to be tested. The model however may provide a methodological basis for ecological risk assessment of heavy metals in soil.

  15. Enhanced leavening properties of baker's yeast by reducing sucrase activity in sweet dough.

    PubMed

    Zhang, Cui-Ying; Lin, Xue; Feng, Bing; Liu, Xiao-Er; Bai, Xiao-Wen; Xu, Jia; Pi, Li; Xiao, Dong-Guang

    2016-07-01

    Leavening ability in sweet dough is required for the commercial applications of baker's yeast. This property depends on many factors, such as glycolytic activity, sucrase activity, and osmotolerance. This study explored the importance of sucrase level on the leavening ability of baker's yeast in sweet dough. Furthermore, the baker's yeast strains with varying sucrase activities were constructed by deleting SUC2, which encodes sucrase or replacing the SUC2 promoter with the VPS8/TEF1 promoter. The results verify that the sucrase activity negatively affects the leavening ability of baker's yeast strains under high-sucrose conditions. Based on a certain level of osmotolerance, sucrase level plays a significant role in the fermentation performance of baker's yeast, and appropriate sucrase activity is an important determinant for the leavening property of baker's yeast in sweet dough. Therefore, modification on sucrase activity is an effective method for improving the leavening properties of baker's yeast in sweet dough. This finding provides guidance for the breeding of industrial baker's yeast strains for sweet dough leavening. The transformants BS1 with deleted SUC2 genetic background provided decreased sucrase activity (a decrease of 39.3 %) and exhibited enhanced leavening property (an increase of 12.4 %). Such a strain could be useful for industrial applications. PMID:27041690

  16. Thermophysical and mechanical properties of Fe-(8-9)%Cr reduced activation steels

    SciTech Connect

    Zinkle, S.J.; Robertson, J.P.; Klueh, R.L.

    1998-09-01

    The key thermophysical and mechanical properties for 8--9%Cr reduced activation ferritic/martensitic steels are summarized, including temperature-dependent tensile properties in the unirradiated and irradiated conditions, stress-rupture behavior, elastic constants, thermal conductivity, thermal expansion, specific heat, and ductile-to-brittle transition temperature. The estimated lower and upper temperatures limits for structural applications are 250 and 550 C due to radiation hardening/embrittlement and thermal creep considerations, respectively.

  17. Antiarrhythmic and antioxidant activity of novel pyrrolidin-2-one derivatives with adrenolytic properties

    PubMed Central

    Nowaczyk, Alicja; Kulig, Katarzyna

    2010-01-01

    A series of novel pyrrolidin-2-one derivatives (17 compounds) with adrenolytic properties was evaluated for antiarrhythmic, electrocardiographic and antioxidant activity. Some of them displayed antiarrhythmic activity in barium chloride-induced arrhythmia and in the rat coronary artery ligation-reperfusion model, and slightly decreased the heart rate, prolonged P–Q, Q–T intervals and QRS complex. Among them, compound EP-40 (1-[2-hydroxy-3-[4-[(2-hydroxyphenyl)piperazin-1-yl]propyl]pyrrolidin-2-one showed excellent antiarrhythmic activity. This compound had significantly antioxidant effect, too. The present results suggest that the antiarrhythmic effect of compound EP-40 is related to their adrenolytic and antioxidant properties. A biological activity prediction using the PASS software shows that compound EP-35 and EP-40 can be characterized by antiischemic activity; whereas, compound EP-68, EP-70, EP-71 could be good tachycardia agents. PMID:20949258

  18. Synthesis, characterization, antimicrobial activity and LPS-interaction properties of SB041, a novel dendrimeric peptide with antimicrobial properties.

    PubMed

    Bruschi, Michela; Pirri, Giovanna; Giuliani, Andrea; Nicoletto, Silvia Fabiole; Baster, Izabela; Scorciapino, Mariano Andrea; Casu, Mariano; Rinaldi, Andrea C

    2010-08-01

    Multimeric peptides offer several advantages with respect to their monomeric counterparts, as increased activity and greater stability to peptidases and proteases. SB041 is a novel antimicrobial peptide with dendrimeric structure; it is a tetramer of pyrEKKIRVRLSA linked by a lysine core, with an amino valeric acid chain. Here, we report on its synthesis, NMR characterization, antimicrobial activity, and LPS-interaction properties. The peptide was especially active against Gram-negative strains, with a potency comparable (on molar basis) to that of lipopeptides colistin and polymixin B, but it also displayed some activity against selected Gram-positive strains. Following these indications, we investigated the efficacy of SB041 in binding Escherichia coli and Pseudomonas aeruginosa LPS in vitro and counteracting its biological effects in RAW-Blue cells, derived from RAW 264.7 macrophages. SB041 strongly bound purified LPS, especially that of E. coli, as proved by fluorescent displacement assay, and readily penetrated into LPS monolayers. However, the killing activity of SB041 against E. coli was not inhibited by increasing concentrations of LPS added to the medium. Checking the SB041 effect on LPS-induced activation of pattern recognition receptors (PRRs) in Raw-Blue cells revealed that while the peptide gave a statistically significant decrease in PRRs stimulation when RAW-Blue cells were challenged with P. aeruginosa LPS, the same was not seen when E. coli LPS was used to activate innate immune defense-like responses. Thus, as previously seen for other antimicrobial peptides, also for SB041 binding to LPS did not translate necessarily into LPS-neutralizing activity, suggesting that SB041-LPS interactions must be of complex nature.

  19. Synthesis of sulfanilamide derivatives and investigation of in vitro inhibitory activities and antimicrobial and physical properties.

    PubMed

    Turkmen, Hasan; Zengin, Gulay; Buyukkircali, Belkis

    2011-06-01

    Novel sulfanilamide derivatives were synthesized and evaluated for carbonic anhydrase inhibitory activity as a target for the treatment of glaucoma, and antibacterial properties for use in chemotherapy. Synthesized compounds were characterized by FT-IR, (1)H NMR, (13)C NMR and photoluminescence. In vitro inhibitory activities were measured by UV-Vis and some of the compounds were found have greater inhibitory effects than the lead compound sulfanilamide. The correlation between inhibitory activity, biological properties and the physicochemical properties of water solubility and partition coefficients was also investigated. Sulfanilamide derivatives gave intense emissions upon irradiation by UV light and a dimethyl substituted compound and a cyclic analog have photoluminescence quantum yields 42% and 31% and long excited-state lifetimes of 3.92 and 2.91 ns, respectively. PMID:21429552

  20. Synthesis, Surface Active Properties and Cytotoxicity of Sodium N-Acyl Prolines.

    PubMed

    Sreenu, Madhumanchi; Narayana Prasad, Rachapudi Badari; Sujitha, Pombala; Kumar, Chityal Ganesh

    2015-01-01

    Sodium N-acyl prolines (NaNAPro) were synthesized using mixture of fatty acids obtained from coconut, palm, karanja, Sterculia foetida and high oleic sunflower oils via Schotten-Baumann reaction in 58-75% yields to study the synergetic effect of mixture of hydrophobic fatty acyl functionalities like saturation, unsaturation and cyclopropene fatty acids with different chain lengths and aliphatic hetero cyclic proline head group on their surface and cytotoxicity activities. The products were characterized by chromatographic and spectral techniques. The synthesized products were evaluated for their surface active properties such as surface tension, wetting power, foaming characteristics, emulsion stability, calcium tolerance, critical micelle concentration (CMC) and thermodynamic properties. The results revealed that all the products exhibited superior surface active properties like CMC, calcium tolerance and emulsion stability as compared to the standard surfactant, sodium lauryl sulphate (SLS). In addition, palm, Sterculia foetida and high oleic sunflower fatty N-acyl prolines exhibited promising cytotoxicity against different tumor cell lines.

  1. [Relationship among soil enzyme activities, vegetation state, and soil chemical properties of coal cinder yard].

    PubMed

    Wang, Youbao; Zhang, Li; Liu, Dengyi

    2003-01-01

    From field investigation and laboratory analysis, the relationships among soil enzyme activities, vegetation state and soil chemical properties of coal cinder yard in thermal power station were studied. The results showed that vegetation on coal cinder yard was distributed in scattered patch mainly with single species of plant, and herbs were the dominant species. At the same time, the activity of three soil enzymes had a stronger relativity to environment conditions, such as vegetation state and soil chemical properties. The sensitivity of three soil enzymes to environmental stress was in order of urease > sucrase > catalase. The relativity of three soil enzymes to environmental factor was in order of sucrase > urease > catalase. Because of urease being the most susceptible enzyme to environmental conditions, and it was marked or utmost marked interrelated with vegetation state and soil chemical properties, urease activity could be used as an indicator for the reclamation of wasteland.

  2. Tobacco guard cells fix CO2 by both Rubisco and PEPcase while sucrose acts as a substrate during light-induced stomatal opening.

    PubMed

    Daloso, Danilo M; Antunes, Werner C; Pinheiro, Daniela P; Waquim, Jardel P; Araújo, Wagner L; Loureiro, Marcelo E; Fernie, Alisdair R; Williams, Thomas C R

    2015-11-01

    Transcriptomic and proteomic studies have improved our knowledge of guard cell function; however, metabolic changes in guard cells remain relatively poorly understood. Here we analysed metabolic changes in guard cell-enriched epidermal fragments from tobacco during light-induced stomatal opening. Increases in sucrose, glucose and fructose were observed during light-induced stomatal opening in the presence of sucrose in the medium while no changes in starch were observed, suggesting that the elevated fructose and glucose levels were a consequence of sucrose rather than starch breakdown. Conversely, reduction in sucrose was observed during light- plus potassium-induced stomatal opening. Concomitant with the decrease in sucrose, we observed an increase in the level as well as in the (13) C enrichment in metabolites of, or associated with, the tricarboxylic acid cycle following incubation of the guard cell-enriched preparations in (13) C-labelled bicarbonate. Collectively, the results obtained support the hypothesis that sucrose is catabolized within guard cells in order to provide carbon skeletons for organic acid production. Furthermore, they provide a qualitative demonstration that CO2 fixation occurs both via ribulose-1,5-biphosphate carboxylase/oxygenase (Rubisco) and phosphoenolpyruvate carboxylase (PEPcase). The combined data are discussed with respect to current models of guard cell metabolism and function.

  3. Spectral and generating properties of active laser media based on dye-doped elastomers

    NASA Astrophysics Data System (ADS)

    Bezrodnyi, Vladimir; Derevyanko, N.; Ishchenko, Alexander A.; Slobodin, Valeriy V.; Karabanova, Ludmila V.

    2002-12-01

    The advantages of a polyurethane matrix over other polymers, which are widely used as active media for dye lasers, are analzyed. This matrix exhibits the photostability, service life, radiation resistance, conversion efficiency, and homogeneity of the dye distribution that surpass these properties for active media based on polyurethane acrylate, which has close physical and operation properties. These advantages result not only from the milder polymerization conditions but also from a lower probability of the formation of ion pairs and dye aggregates. A substantial suppression of these processes in polyurethane is explained by its greater polarity and solvation ability compared to polyurathane acrylate.

  4. Properties and active substance release kinetics from gelatin-alginate matrices.

    PubMed

    Pluta, Janusz; Haznar, Dorota

    2006-01-01

    The aim of the study was to evaluate the effect of composition and technological processing on pharmaceutical availability of active substance as well as on the properties of porous gelatin-alginate matrices. The active substance carrier included glycerol or peanut oil apart from gelatin and sodium alginate, and some matrices were additionally modified with calcium lactate. The obtained matrices were characterized by good sorption properties and high resistance to proteolytic enzymes. The release of the model antibiotic followed the pattern of first order kinetics, while half-release time in vitro (in the experimental conditions) was 1.5 to 3 hrs.

  5. [Graded ethanol precipitation method on physicochemical properties and antioxidant activities of polysaccharides extracted from Astragalus Radix].

    PubMed

    Li, Hong-fa; Guo, Song-bo; Man, Shu-li; Fan, Ya-ya; Wang, Ting-ting; Li, Xia; Gao, Wen-yuan

    2015-06-01

    Astragalus polysaccharide has been widely used in food and medicinal industry owing to its health-promoting properties. In order to characterize better the relationship among molecular weight, structure-activity and activities, a simple method was used different concentration of ethanol including 30% (PW30), 50% (PW50), 70% (PW70), 75% (PW75), 80% (PW80) and 90% (PW90) to precipitate Astragalus polysaccharides into different molecular weight. As a result, PW90 showed smooth surface and the strongest antioxidant activity among these six fractions (P < 0.05). In conclusion, graded ethanol precipitation was a simple method to separate Astragalus polysaccharides into different molecular weight with different antioxidant activity fractions.

  6. Self-assembly of cationic multidomain peptide hydrogels: supramolecular nanostructure and rheological properties dictate antimicrobial activity.

    PubMed

    Jiang, Linhai; Xu, Dawei; Sellati, Timothy J; Dong, He

    2015-12-01

    Hydrogels are an important class of biomaterials that have been widely utilized for a variety of biomedical/medical applications. The biological performance of hydrogels, particularly those used as wound dressing could be greatly advanced if imbued with inherent antimicrobial activity capable of staving off colonization of the wound site by opportunistic bacterial pathogens. Possessing such antimicrobial properties would also protect the hydrogel itself from being adversely affected by microbial attachment to its surface. We have previously demonstrated the broad-spectrum antimicrobial activity of supramolecular assemblies of cationic multi-domain peptides (MDPs) in solution. Here, we extend the 1-D soluble supramolecular assembly to 3-D hydrogels to investigate the effect of the supramolecular nanostructure and its rheological properties on the antimicrobial activity of self-assembled hydrogels. Among designed MDPs, the bactericidal activity of peptide hydrogels was found to follow an opposite trend to that in solution. Improved antimicrobial activity of self-assembled peptide hydrogels is dictated by the combined effect of supramolecular surface chemistry and storage modulus of the bulk materials, rather than the ability of individual peptides/peptide assemblies to penetrate bacterial cell membrane as observed in solution. The structure-property-activity relationship developed through this study will provide important guidelines for designing biocompatible peptide hydrogels with built-in antimicrobial activity for various biomedical applications.

  7. Interactions of C4 subtype metabolic activities and transport in maize are revealed through the characterization of DCT2 mutants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    C4 photosynthesis is an elaborate set of metabolic pathways that utilize specialized anatomical and biochemical adaptations to concentrate CO2 around RuBisCO. The activities of the C4 pathways are coordinated between two specialized leaf cell types, mesophyll (M) and bundle sheath (BS), and rely hea...

  8. Unprecedented activation and CO2 capture properties of an elastic single-molecule trap.

    PubMed

    Wriedt, Mario; Sculley, Julian P; Verdegaal, Wolfgang M; Yakovenko, Andrey A; Zhou, Hong-Cai

    2013-10-25

    The activation and CO2 capture properties of a microporous metal-organic framework with elastic single-molecule traps were systematically investigated. This material shows a unique low-energy gas-purge activation capability, high CO2 adsorption selectivities over various gases and optimized working capacities per energy of 2.9 mmol kJ(-1) at 128 °C. PMID:24022838

  9. Properties of Ce-activated alkali-lutetium double phosphate scintillators

    SciTech Connect

    Wiśniewski, D.; Wojtowicz, A. J.; Boatner, Lynn A

    2010-01-01

    The scintillation properties of Ce-activated alkali-lutetium double phosphate single crystals that vary with the alkali ion type and activation level are summarized and compared. The materials investigated here have been identified as fast and efficient scintillators for the detection of x-ray and radiation, and in case of Li3Lu(PO4)2:Ce, for thermal neutron detection as well.

  10. Influence of Copper Nanoparticles on the Physical-Chemical Properties of Activated Sludge

    PubMed Central

    Chen, Hong; Zheng, Xiong; Chen, Yinguang; Li, Mu; Liu, Kun; Li, Xiang

    2014-01-01

    The physical-chemical properties of activated sludge, such as flocculating ability, hydrophobicity, surface charge, settleability, dewaterability and bacteria extracellular polymer substances (EPS), play vital roles in the normal operation of wastewater treatment plants (WWTPs). The nanoparticles released from commercial products will enter WWTPs and can induce potential adverse effects on activated sludge. This paper focused on the effects of copper nanoparticles (CuNPs) on these specific physical-chemical properties of activated sludge. It was found that most of these properties were unaffected by the exposure to lower CuNPs concentration (5 ppm), but different observation were made at higher CuNPs concentrations (30 and 50 ppm). At the higher CuNPs concentrations, the sludge surface charge increased and the hydrophobicity decreased, which were attributed to more Cu2+ ions released from the CuNPs. The carbohydrate content of EPS was enhanced to defense the toxicity of CuNPs. The flocculating ability was found to be deteriorated due to the increased cell surface charge, the decreased hydrophobicity, and the damaged cell membrane. The worsened flocculating ability made the sludge flocs more dispersed, which further increased the toxicity of the CuNPs by increasing the availability of the CuNPs to the bacteria present in the sludge. Further investigation indicated that the phosphorus removal efficiency decreased at higher CuNPs concentrations, which was consistent with the deteriorated physical-chemical properties of activated sludge. It seems that the physical-chemical properties can be used as an indicator for determining CuNPs toxicity to the bacteria in activated sludge. This work is important because bacteria toxicity effects to the activated sludge caused by nanoparticles may lead to the deteriorated treatment efficiency of wastewater treatment, and it is therefore necessary to find an easy way to indicate this toxicity. PMID:24663333

  11. Influence of copper nanoparticles on the physical-chemical properties of activated sludge.

    PubMed

    Chen, Hong; Zheng, Xiong; Chen, Yinguang; Li, Mu; Liu, Kun; Li, Xiang

    2014-01-01

    The physical-chemical properties of activated sludge, such as flocculating ability, hydrophobicity, surface charge, settleability, dewaterability and bacteria extracellular polymer substances (EPS), play vital roles in the normal operation of wastewater treatment plants (WWTPs). The nanoparticles released from commercial products will enter WWTPs and can induce potential adverse effects on activated sludge. This paper focused on the effects of copper nanoparticles (CuNPs) on these specific physical-chemical properties of activated sludge. It was found that most of these properties were unaffected by the exposure to lower CuNPs concentration (5 ppm), but different observation were made at higher CuNPs concentrations (30 and 50 ppm). At the higher CuNPs concentrations, the sludge surface charge increased and the hydrophobicity decreased, which were attributed to more Cu2+ ions released from the CuNPs. The carbohydrate content of EPS was enhanced to defense the toxicity of CuNPs. The flocculating ability was found to be deteriorated due to the increased cell surface charge, the decreased hydrophobicity, and the damaged cell membrane. The worsened flocculating ability made the sludge flocs more dispersed, which further increased the toxicity of the CuNPs by increasing the availability of the CuNPs to the bacteria present in the sludge. Further investigation indicated that the phosphorus removal efficiency decreased at higher CuNPs concentrations, which was consistent with the deteriorated physical-chemical properties of activated sludge. It seems that the physical-chemical properties can be used as an indicator for determining CuNPs toxicity to the bacteria in activated sludge. This work is important because bacteria toxicity effects to the activated sludge caused by nanoparticles may lead to the deteriorated treatment efficiency of wastewater treatment, and it is therefore necessary to find an easy way to indicate this toxicity.

  12. Tuning of fast-spiking interneuron properties by an activity-dependent transcriptional switch*

    PubMed Central

    Dehorter, Nathalie; Ciceri, Gabriele; Bartolini, Giorgia; Lim, Lynette; del Pino, Isabel; Marín, Oscar

    2015-01-01

    The function of neural circuits depends on the generation of specific classes of neurons. Neural identity is typically established near the time when neurons exit the cell cycle to become postmitotic cells, and it is generally accepted that, once the identity of a neuron has been established, its fate is maintained throughout life. Here, we show that network activity dynamically modulates the properties of fast-spiking (FS) interneurons through the postmitotic expression of the transcriptional regulator Er81. In the adult cortex, Er81 protein levels define a spectrum of FS basket cells with different properties, whose relative proportions are, however, continuously adjusted in response to neuronal activity. Our findings therefore suggest that interneuron properties are malleable in the adult cortex, at least to a certain extent. PMID:26359400

  13. ENVIRONMENTAL DEPENDENCE OF OTHER GALAXY PROPERTIES FOR THE SAME STAR FORMATION ACTIVITIES

    SciTech Connect

    Deng Xinfa; Bei Yang; He Jizhou; Tang Xiaoxun

    2010-01-01

    Using two volume-limited Main galaxy samples of the Sloan Digital Sky Survey Data Release 6 above and below the value of M*, we have investigated the environmental dependence of other galaxy properties for the same star formation activities. Only in the luminous passive class, a strong environmental dependence of the g - r color is observed, but the environmental dependence of other properties in this class is very weak. In other classes, we can conclude that the local density dependence of luminosity, g - r color, concentration index ci, and morphologies for star-forming galaxies and passive ones is much weaker than that obtained in the volume-limited Main galaxy samples. This suggests that star formation activity is a galaxy property very predictive of the local environment. In addition, we also note that passive galaxies are more luminous, redder, highly concentrated, and preferentially 'early type'.

  14. Influence of jet-cooking Prowashonupana barley flour on phenolic composition, antioxidant activities, and viscoelastic properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The influence of jet-cooking Prowashonupana barley flour on total phenolic contents, antioxidant activities, water holding capacities, and viscoelastic properties was studied. Barley flour was jet-cooked without or with pH adjustment at 7, 9, or 11. Generally, the free phenolic content and antioxi...

  15. Engineering support activities for the Apollo 17 Surface Electrical Properties Experiment.

    NASA Technical Reports Server (NTRS)

    Cubley, H. D.

    1972-01-01

    Description of the engineering support activities which were required to ensure fulfillment of objectives specified for the Apollo 17 SEP (Surface Electrical Properties) Experiment. Attention is given to procedural steps involving verification of hardware acceptability to the astronauts, computer simulation of the experiment hardware, field trials, receiver antenna pattern measurements, and the qualification test program.

  16. Antitumor properties and modulation of antioxidant enzymes' activity by Aloe vera leaf active principles isolated via supercritical carbon dioxide extraction.

    PubMed

    El-Shemy, H A; Aboul-Soud, M A M; Nassr-Allah, A A; Aboul-Enein, K M; Kabash, A; Yagi, A

    2010-01-01

    The aim of this study was to evaluate the potential anticancer properties and modulatory effect of selected Aloe vera (A. vera) active principles on antioxidant enzyme activities. Thus, three anthraquinones (Namely: aloesin, aloe-emodin and barbaloin) were extracted from A. vera leaves by supercritical fluid extraction and subsequently purified by high performance liquid chromatography. Additionally, the N-terminal octapeptide derived from verectin, a biologically active 14 kDa glycoprotein present in A. vera, was also tested. In vivo, active principles exhibited significant prolongation of the life span of tumor-transplanted animals in the following order: barbaloin> octapeptide> aloesin > aloe-emodin. A. vera active principles exhibited significant inhibition on Ehrlich ascite carcinoma cell (EACC) number, when compared to positive control group, in the following order: barbaloin> aloe-emodin > octapeptide > aloesin. Moreover, in trypan blue cell viability assay, active principles showed a significant concentration-dependent cytotoxicity against acute myeloid leukemia (AML) and acute lymphocytes leukemia (ALL) cancerous cells. Furthermore, in MTT cell viability test, aloe-emodin was found to be active against two human colon cancer cell lines (i.e. DLD-1 and HT2), with IC(50) values of 8.94 and 10.78 microM, respectively. Treatments of human AML leukemic cells with active principles (100 microg ml(-1)) resulted in varying intensities of internucleosomal DNA fragmentation, hallmark of cells undergoing apoptosis, in the following order: aloe-emodin> aloesin> barbaloin> octapeptide. Intererstingly, treatment of EACC tumors with active principles resulted in a significant elevation activity of key antioxidant enzymes (SOD, GST, tGPx, and LDH). Our data suggest that the tested A. vera compounds may exert their chemo-preventive effect through modulating antioxidant and detoxification enzyme activity levels, as they are one of the indicators of tumorigenesis. These

  17. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.

    Several court cases involving acquisition, use, and disposal of property by institutions of higher education are briefly summarized in this chapter. Cases discussed touch on such topics as municipal annexation of university property; repurchase of properties temporarily allocated to faculty members; implications of zoning laws and zoning board…

  18. Investigation of membrane active properties and antiradical activity of gossypol and its derivatives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    New asymmetrical derivatives of gossypol were synthesized. The antioxidant activity of gossypol and these derivatives was studied. The interaction of these compounds with modeled lipid membranes was also studied. It was found that the antioxidant effects and ability to interact with membranes was...

  19. Membrane-Active Properties and Antiradical Activity of Gossypol and Its Derivatives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    New asymmetrical derivatives of gossypol were synthesized. The antioxidant activity of gossypol and these derivatives was studied. The interaction of these compounds with modeled lipid membranes was also studied. It was found that the antioxidant effects and ability to interact with membranes was...

  20. Physicochemical properties and antioxidant activities of polysaccharides sequentially extracted from peony seed dreg.

    PubMed

    Shi, Jun-Jun; Zhang, Jian-Guo; Sun, Yu-Han; Qu, Jie; Li, Ling; Prasad, Chandan; Wei, Zhao-Jun

    2016-10-01

    The sequential extraction of peony seed dreg polysaccharides (PSDP) with hot buffer (HBSS), chelating agent (CHSS), dilute alkaline (DASS) and concentrated alkaline (CASS) yielded four different polysaccharide fractions. Based on their absorptions at 3600-3200cm(-1) and 1200-800cm(-1), these fractions were confirmed to be polysaccharides. The properties of four PSDPs displayed some slight differences. The CASS showed the highest peak temperature and endothermic enthalpy. The emulsifying activity and emulsifying stability of four PSDPs exhibited a dose-dependent pattern; HBSS showed the highest emulsifying activity, and CHSS displayed the longest emulsifying stability. The four PSDPs also exhibited wide variations in their antioxidant activities. For example, i) CASS showed the highest DPPH radical scavenging activity, reducing power and ABTS radical scavenging activity; ii) HBSS exhibited the highest hydroxyl radical scavenging activity, and iii) CHSS displayed the higher ferrous ions chelating ability than others. PMID:27234494

  1. Preparation and properties of silver nanoparticles loaded in activated carbon for biological and environmental applications.

    PubMed

    Tran, Quoc Tuan; Nguyen, Van Son; Hoang, Thi Kim Dung; Nguyen, Hoang Luong; Bui, Thu Thuy; Nguyen, Thi Van Anh; Nguyen, Dinh Hoa; Nguyen, Hoang Hai

    2011-09-15

    Silver nanoparticles colloid has been prepared by a modified sonoelectrodeposition technique in which a silver plate was used as the source of silver ions. This technique allows producing Ag nanoparticles with the size of 4-30 nm dispersed in a non-toxic solution. The Ag nanoparticles were loaded in a high surface activated carbon produced from coconut husk, a popular agricultural waste in Vietnam by thermal activation. The surface area of the best activated carbon is 890 m(2)/g. The presence of Ag nanoparticles does not change significantly properties of the activated carbon in terms of morphology and methylene blue adsorption ability. The Ag nanoparticle-loaded activated carbon shows a good antibacterial activity against Escherichia coli with very low minimal inhibitory concentration of 16 μg/ml and strong As(V) adsorption. The materials are potential for prevention and treatment of microbial infection and contamination for environmental applications.

  2. Development of an active food packaging system with antioxidant properties based on green tea extract.

    PubMed

    Carrizo, Daniel; Gullo, Giuseppe; Bosetti, Osvaldo; Nerín, Cristina

    2014-01-01

    A formula including green tea extract (GTE) was developed as an active food packaging material. This formula was moulded to obtain an independent component/device with antioxidant properties that could be easily coupled to industrial degassing valves for food packaging in special cases. GTE components (i.e., gallic acid, catechins and caffeine) were identified and quantified by HPLC-UV and UPLC-MS and migration/diffusion studies were carried out. Antioxidant properties of the formula alone and formula-valve were measured with static and dynamic methods. The results showed that the antioxidant capacity (scavenging of free radicals) of the new GTE formula was 40% higher than the non-active system (blank). This antioxidant activity increased in parallel with the GTE concentration. The functional properties of the industrial target valve (e.g., flexibility) were studied for different mixtures of GTE, and good results were found with 17% (w/w) of GTE. This new active formula can be an important addition for active packaging applications in the food packaging industry, with oxidative species-scavenging capacity, thus improving the safety and quality for the consumer and extending the shelf-life of the packaged food.

  3. Activity patterns in the Sahara Desert: an interpretation based on cross-sectional geometric properties.

    PubMed

    Nikita, Efthymia; Siew, Yun Ysi; Stock, Jay; Mattingly, David; Lahr, Marta Mirazón

    2011-11-01

    The Garamantian civilization flourished in modern Fezzan, Libya, between 900 BC and 500 AD, during which the aridification of the Sahara was well established. Study of the archaeological remains suggests a population successful at coping with a harsh environment of high and fluctuating temperatures and reduced water and food resources. This study explores the activity patterns of the Garamantes by means of cross-sectional geometric properties. Long bone diaphyseal shape and rigidity are compared between the Garamantes and populations from Egypt and Sudan, namely from the sites of Kerma, el-Badari, and Jebel Moya, to determine whether the Garamantian daily activities were more strenuous than those of other North African populations. Moreover, sexual dimorphism and bilateral asymmetry are assessed at an intra- and inter-population level. The inter-population comparisons showed the Garamantes not to be more robust than the comparative populations, suggesting that the daily Garamantian activities necessary for survival in the Sahara Desert did not generally impose greater loads than those of other North African populations. Sexual dimorphism and bilateral asymmetry in almost all geometric properties of the long limbs were comparatively low among the Garamantes. Only the lower limbs were significantly stronger among males than females, possibly due to higher levels of mobility associated with herding. The lack of systematic bilateral asymmetry in cross-sectional geometric properties may relate to the involvement of the population in bilaterally intensive activities or the lack of regular repetition of unilateral activities.

  4. Insights into properties of activated carbons prepared from different raw precursors by pyrophosphoric acid activation.

    PubMed

    Gao, Yuan; Yue, Qinyan; Gao, Baoyu

    2016-03-01

    Low-cost activated carbons (ACs) were prepared from four kinds of solid wastes: petroleum coke, Enteromorpha prolifera, lignin from papermaking black liquid and hair, by pyrophosphoric acid (H4P2O7) activation. Thermo-gravimetric analysis of the pyrolysis of H4P2O7-precursor mixtures implied that H4P2O7 had different influences on the pyrolysis behavior of the four raw materials. N2 adsorption/desorption isotherms, scanning electron microscopy, Fourier transform infrared spectroscopy and adsorption capacities for dyes were used to characterize the prepared activated carbons. AC derived from E. prolifera exhibited the highest surface area (1094m(2)/g) and maximum monolayer adsorption capacity for malachite green (1250mg/g). Kinetic studies showed that the experimental data were in agreement with the pseudo-second-order model. The adsorption isotherms were well described by the Langmuir isotherm model, indicating the adsorption of dye onto the ACs proceeded by monolayers. PMID:26969070

  5. Molecular and structural properties of polymer composites filled with activated charcoal particles

    NASA Astrophysics Data System (ADS)

    Tahir, Dahlang; Liong, Syarifuddin; Bakri, Fahrul

    2016-03-01

    We have studied the molecular properties, structural properties, and chemical composition of composites by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, and X-ray fluorescence (XRF) spectroscopy, respectively. FTIR spectra shows absorption band of hydroxyl group (-OH), methyl group (-CH3) and aromatic group (C-C). The absorption band for aromatic group (C-C) shows the formation of carbonaceous in composites. XRF shows chemical composition of composites, which the main chemicals are SO3, Cl, and ZnO. The loss on ignition value (LOI) of activated charcoal indicates high carbonaceous matter. The crystallite size for diffraction pattern from hydrogel polymer is about 17 nm and for activated charcoal are about 19 nm. The crystallite size of the polymer is lower than that of activated charcoal, which make possible of the particle from filler in contact with each other to form continuous conducting polymer through polymer matrix.

  6. Radiative recombination from dark excitons in nanocrystals: Activation mechanisms and polarization properties

    NASA Astrophysics Data System (ADS)

    Rodina, Anna V.; Efros, Alexander L.

    2016-04-01

    We analyze theoretically physical mechanisms responsible for the radiative recombination of the ground optically passive ("dark") exciton (DE), which dominates in photoluminescence (PL) of colloidal nanocrystals (NCs) at low temperatures. The DE becomes optically active due to its mixing with the bright excitons caused by an external magnetic field, dangling-bond spins or by acoustic and optical phonons. These activation mechanisms mix the DE with different bright excitons and, consequently, lead to different PL polarization properties, because they are determined by dipole orientations of the bright excitons, which the DE is coupled with. We show that the PL polarization properties of prolate and oblate shape NCs are different due to different activation mechanisms responsible for the DE recombination.

  7. Anisotropic Elastography for Local Passive Properties and Active Contractility of Myocardium from Dynamic Heart Imaging Sequence

    PubMed Central

    Wang, Ge; Sun, L. Z.

    2006-01-01

    Major heart diseases such as ischemia and hypertrophic myocardiopathy are accompanied with significant changes in the passive mechanical properties and active contractility of myocardium. Identification of these changes helps diagnose heart diseases, monitor therapy, and design surgery. A dynamic cardiac elastography (DCE) framework is developed to assess the anisotropic viscoelastic passive properties and active contractility of myocardial tissues, based on the chamber pressure and dynamic displacement measured with cardiac imaging techniques. A dynamic adjoint method is derived to enhance the numerical efficiency and stability of DCE. Model-based simulations are conducted using a numerical left ventricle (LV) phantom with an ischemic region. The passive material parameters of normal and ischemic tissues are identified during LV rapid/reduced filling and artery contraction, and those of active contractility are quantified during isovolumetric contraction and rapid/reduced ejection. It is found that quasistatic simplification in the previous cardiac elastography studies may yield inaccurate material parameters. PMID:23165032

  8. Do maise and wheat chloroplast protein synthesis elongation factor, EF-Tu, protect Rubisco activase from thermal aggregation and inactivation?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize (Zea mays L.) chloroplast protein synthesis elongation factor, EF-Tu, has been implicated in the development of heat tolerance. The precursor of this protein (pre-EF-Tu) has been shown to display chaperone activity, as it protected heat labile citrate synthase and malate dehydrogenase from the...

  9. Mechanical and microstructural properties of alkali-activated fly ash geopolymers.

    PubMed

    Komljenović, M; Bascarević, Z; Bradić, V

    2010-09-15

    This paper investigates the properties of geopolymer obtained by alkali-activation of fly ash (FA), i.e. the influence of characteristics of the representative group of FA (class F) from Serbia, as well as that of the nature and concentration of various activators on mechanical and microstructural properties of geopolymers. Aqueous solutions of Ca(OH)(2), NaOH, NaOH+Na(2)CO(3), KOH and sodium silicate (water glass) of various concentrations were used as alkali activators. It was established that the nature and concentration of the activator was the most dominant parameter in the alkali-activation process. In respect of physical characteristics of FA, the key parameter was fineness. The geopolymer based on FA with the highest content of fine particles (<43 microm), showed the highest compressive strength in all cases. Regardless of FA characteristics, nature and concentration of the activator, the alkali-activation products were mainly amorphous. The formation of crystalline phases (zeolites) occurred in some cases, depending on the reaction conditions. The highest compressive strength was obtained using sodium silicate. Together with the increase of sodium silicate SiO(2)/Na(2)O mass ratio, the atomic Si/Al ratio in the reaction products was also increased. Under the experimental conditions of this investigation, high strength was directly related to the high Si/Al ratio.

  10. Chemical analysis of Greek pollen - Antioxidant, antimicrobial and proteasome activation properties

    PubMed Central

    2011-01-01

    Background Pollen is a bee-product known for its medical properties from ancient times. In our days is increasingly used as health food supplement and especially as a tonic primarily with appeal to the elderly to ameliorate the effects of ageing. In order to evaluate the chemical composition and the biological activity of Greek pollen which has never been studied before, one sample with identified botanical origin from sixteen different common plant taxa of Greece has been evaluated. Results Three different extracts of the studied sample of Greek pollen, have been tested, in whether could induce proteasome activities in human fibroblasts. The water extract was found to induce a highly proteasome activity, showing interesting antioxidant properties. Due to this activity the aqueous extract was further subjected to chemical analysis and seven flavonoids have been isolated and identified by modern spectral means. From the methanolic extract, sugars, lipid acids, phenolic acids and their esters have been also identified, which mainly participate to the biosynthetic pathway of pollen phenolics. The total phenolics were estimated with the Folin-Ciocalteau reagent and the total antioxidant activity was determined by the DPPH method while the extracts and the isolated compounds were also tested for their antimicrobial activity by the dilution technique. Conclusions The Greek pollen is rich in flavonoids and phenolic acids which indicate the observed free radical scavenging activity, the effects of pollen on human fibroblasts and the interesting antimicrobial profile. PMID:21699688

  11. Mechanical and microstructural properties of alkali-activated fly ash geopolymers.

    PubMed

    Komljenović, M; Bascarević, Z; Bradić, V

    2010-09-15

    This paper investigates the properties of geopolymer obtained by alkali-activation of fly ash (FA), i.e. the influence of characteristics of the representative group of FA (class F) from Serbia, as well as that of the nature and concentration of various activators on mechanical and microstructural properties of geopolymers. Aqueous solutions of Ca(OH)(2), NaOH, NaOH+Na(2)CO(3), KOH and sodium silicate (water glass) of various concentrations were used as alkali activators. It was established that the nature and concentration of the activator was the most dominant parameter in the alkali-activation process. In respect of physical characteristics of FA, the key parameter was fineness. The geopolymer based on FA with the highest content of fine particles (<43 microm), showed the highest compressive strength in all cases. Regardless of FA characteristics, nature and concentration of the activator, the alkali-activation products were mainly amorphous. The formation of crystalline phases (zeolites) occurred in some cases, depending on the reaction conditions. The highest compressive strength was obtained using sodium silicate. Together with the increase of sodium silicate SiO(2)/Na(2)O mass ratio, the atomic Si/Al ratio in the reaction products was also increased. Under the experimental conditions of this investigation, high strength was directly related to the high Si/Al ratio. PMID:20554110

  12. Fractionation, physicochemical property and immunological activity of polysaccharides from Cassia obtusifolia.

    PubMed

    Feng, Lei; Yin, Junyi; Nie, Shaoping; Wan, Yiqun; Xie, Mingyong

    2016-10-01

    The seeds of Cassia obtusifolia are widely used as a drink in Asia and an additive in food industry. Considerable amounts of water-soluble polysaccharides were found in the whole seeds, while conflicting results on structure characteristics have been reported, and few studies have been reported on physicochemical properties and immunomodulatory activities. In the present study, gradient ethanol precipitation was applied to fractionate the water-soluble polysaccharide (CP), and two sub-fractions CP-30 (30% ethanol precipitate) and CP-40 (40% ethanol precipitate) were obtained. Different rheological properties for CP-30 and CP-40 were found, indicating the differences in structure characteristics between CP-30 and CP-40. Chemical properties, including molecular weight, monosaccharide composition, and glycosidic linkage were investigated. Compared with CP-30, CP-40 had lower molecular weight and higher content of xylose. The immunomodulatory effects of CP, CP-30 and CP-40 were assessed. All of them were found to possess significant immunomodulation activities, while varied effects of them on macrophage functions were observed. The aim of the present study was to develop a simple and efficient method to purify cassia polysaccharides, and investigate their physicochemical properties and biological activities, which was meaningful for their potential use in food industry and folk medicine. PMID:27177462

  13. Electrochemical and fluorescence properties of SnO2 thin films and its antibacterial activity.

    PubMed

    Henry, J; Mohanraj, K; Sivakumar, G; Umamaheswari, S

    2015-05-15

    Nanocrystalline SnO2 thin films were deposited by a simple and inexpensive sol-gel spin coating technique and the films were annealed at two different temperatures (350°C and 450°C). Structural, vibrational, optical and electrochemical properties of the films were analyzed using XRD, FTIR, UV-Visible, fluorescence and cyclic voltammetry techniques respectively and their results are discussed in detail. The antimicrobial properties of SnO2 thin films were investigated by agar agar method and the results confirm the antibacterial activity of SnO2 against Escherichiacoli and Bacillus. PMID:25727293

  14. The Autophagic Degradation of Chloroplasts via Rubisco-Containing Bodies Is Specifically Linked to Leaf Carbon Status But Not Nitrogen Status in Arabidopsis1[W][OA

    PubMed Central

    Izumi, Masanori; Wada, Shinya; Makino, Amane; Ishida, Hiroyuki

    2010-01-01

    Autophagy is an intracellular process facilitating the vacuolar degradation of cytoplasmic components and is important for nutrient recycling during starvation. We previously demonstrated that chloroplasts can be partially mobilized to the vacuole by autophagy via spherical bodies named Rubisco-containing bodies (RCBs). Although chloroplasts contain approximately 80% of total leaf nitrogen and represent a major carbon and nitrogen source for new growth, the relationship between leaf nutrient status and RCB production remains unclear. We examined the effects of nutrient factors on the appearance of RCBs in leaves of transgenic Arabidopsis (Arabidopsis thaliana) expressing stroma-targeted fluorescent proteins. In excised leaves, the appearance of RCBs was suppressed by the presence of metabolic sugars, which were added externally or were produced during photosynthesis in the light. The light-mediated suppression was relieved by the inhibition of photosynthesis. During a diurnal cycle, RCB production was suppressed in leaves excised at the end of the day with high starch content. Starchless mutants phosphoglucomutase and ADP-Glc pyrophosphorylase1 produced a large number of RCBs, while starch-excess mutants starch-excess1 and maltose-excess1 produced fewer RCBs. In nitrogen-limited plants, as leaf carbohydrates were accumulated, RCB production was suppressed. We propose that there exists a close relationship between the degradation of chloroplast proteins via RCBs and leaf carbon but not nitrogen status in autophagy. We also found that the appearance of non-RCB-type autophagic bodies was not suppressed in the light and somewhat responded to nitrogen in excised leaves, unlike RCBs. These results imply that the degradation of chloroplast proteins via RCBs is specifically controlled in autophagy. PMID:20807997

  15. Changes in the delta13C values of trees during a tropical rainy season: some effects in addition to diffusion and carboxylation by Rubisco?

    PubMed

    Terwilliger, V

    1997-12-01

    The d13C values of deciduous and evergreen tree leaves were compared in open and closed- canopy environments throughout a rainy season in Panamá. Newly emerging leaves had higher d13C values than older leaves of all seedlings and trees at all dates sampled. This was apparently not caused by a decline in water use efficiency as leaves develop because instantaneous ci/ca was significantly higher in newly emerging than in expanded leaves on the same twigs of trees in the field as well as on seedlings growing in a controlled, unchanging environment. Higher d13C values in newly emerging leaves occurred across diverse environmental comparisons. For example, leaves emerging during the rainy season had higher d13C values than corresponding mature leaves that had emerged both during the dry season and when water was abundant. The early enrichment in 13C may thus reflect the translocation of carbon to initiate a new leaf. Furthermore, the lack of sensitivity of this enrichment to a microclimate suggests that it might be the result of processes that occur after carbon fixation by Rubisco. Other changes in d13C values as leaves developed may also have resulted from carbon translocation processes. Foliar d13C decreased significantly after most of the leaf biomass of the deciduous Apeiba membranacea had developed. The d13C values of the evergreen Cecropia insignis were lower in the open canopy than in closed-canopy forests at the end of the rainy season. These findings suggest that the d13C values of leaves can yield ecological information about the allocation of carbon within trees.

  16. Piezoelectric properties of the new generation active matrix hybrid (micro-nano) composites

    NASA Astrophysics Data System (ADS)

    Parali, Levent; Şabikoğlu, İsrafil; Kurbanov, Mirza A.

    2014-11-01

    A hybrid piezoelectric composite structure is obtained by addition of nano-sized BaTiO3, SiO2 to the micro-sized PZT and polymers composition. Although the PZT material itself has excellent piezoelectric properties, PZT-based composite variety is limited. Piezoelectric properties of PZT materials can be varied with an acceptor or a donor added to the material. In addition, varieties of PZT-based sensors can be increased with doping polymers which have physical-mechanical, electrophysical, thermophysical and photoelectrical properties. The active matrix hybrid structure occurs when bringing together the unique piezoelectric properties of micro-sized PZT with electron trapping properties of nano-sized insulators (BaTiO3 or SiO2), and their piezoelectric, mechanic and electromechanic properties significantly change. In this study, the relationship between the piezoelectric constant and the coupling factor values of microstructure (PZT-PVDF) and the hybrid structure (PZT-PVDF-BaTiO3) composite are compared. The d33 value and the coupling factor of the hybrid structure have shown an average of 54 and 62% increase according to microstructure composite, respectively. In addition, the d33 value and the coupling factor of the hybrid structure (PZT-HDPE-SiO2) have exhibited about 68 and 52% increase according to microstructure composite (PZT-HDPE), respectively.

  17. Self-assembly of cationic multidomain peptide hydrogels: supramolecular nanostructure and rheological properties dictate antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Jiang, Linhai; Xu, Dawei; Sellati, Timothy J.; Dong, He

    2015-11-01

    Hydrogels are an important class of biomaterials that have been widely utilized for a variety of biomedical/medical applications. The biological performance of hydrogels, particularly those used as wound dressing could be greatly advanced if imbued with inherent antimicrobial activity capable of staving off colonization of the wound site by opportunistic bacterial pathogens. Possessing such antimicrobial properties would also protect the hydrogel itself from being adversely affected by microbial attachment to its surface. We have previously demonstrated the broad-spectrum antimicrobial activity of supramolecular assemblies of cationic multi-domain peptides (MDPs) in solution. Here, we extend the 1-D soluble supramolecular assembly to 3-D hydrogels to investigate the effect of the supramolecular nanostructure and its rheological properties on the antimicrobial activity of self-assembled hydrogels. Among designed MDPs, the bactericidal activity of peptide hydrogels was found to follow an opposite trend to that in solution. Improved antimicrobial activity of self-assembled peptide hydrogels is dictated by the combined effect of supramolecular surface chemistry and storage modulus of the bulk materials, rather than the ability of individual peptides/peptide assemblies to penetrate bacterial cell membrane as observed in solution. The structure-property-activity relationship developed through this study will provide important guidelines for designing biocompatible peptide hydrogels with built-in antimicrobial activity for various biomedical applications.Hydrogels are an important class of biomaterials that have been widely utilized for a variety of biomedical/medical applications. The biological performance of hydrogels, particularly those used as wound dressing could be greatly advanced if imbued with inherent antimicrobial activity capable of staving off colonization of the wound site by opportunistic bacterial pathogens. Possessing such antimicrobial properties would

  18. Physicochemical Properties That Enhance Discriminative Antibacterial Activity of Short Dermaseptin Derivatives

    PubMed Central

    Rotem, Shahar; Radzishevsky, Inna; Mor, Amram

    2006-01-01

    Antimicrobial peptides are widely believed to exert their effects by nonspecific mechanisms. We assessed the extent to which physicochemical properties can be exploited to promote discriminative activity by manipulating the N-terminal sequence of the 13-mer dermaseptin derivative K4-S4(1-13) (P). Inhibitory activity determined in culture media against 16 strains of bacteria showed that when its hydrophobicity and charge were changed, P became predominantly active against either gram-positive or gram-negative bacteria. Thus, conjugation of various aminoacyl-lysin moieties (e.g., aminohexyl-K-P) led to inactivity against gram-positive bacteria (MIC50 > 50 μM) but potent activity against gram-negative bacteria (MIC50, 6.2 μM). Conversely, conjugation of equivalent acyls to the substituted analog M4-S4(1-13) (e.g., hexyl-M4-P) led to inactivity against gram-negative bacteria (MIC50 > 50 μM) but potent activity against gram-positive bacteria (MIC50, 3.1 μM). Surface plasmon resonance experiments, used to investigate peptides' binding properties to lipopolysaccharide-containing idealized phospholipid membranes, suggest that although the acylated derivatives have increased lipophilic properties with parallel antibacterial behavior, hydrophobic derivatives are prevented from reaching the cytoplasmic membranes of gram-negative bacteria. Moreover, unlike modifications that enhanced the activity against gram-positive bacteria, which also enhanced hemolysis, we found that modifications that enhanced activity against gram-negative bacteria generally reduced hemolysis. Thus, compared with the clinically tested peptides MSI-78 and IB-367, the dermaseptin derivative aminohexyl-K-P performed similarly in terms of potency and bactericidal kinetics but was significantly more selective in terms of discrimination between bacteria and human erythrocytes. Overall, the data suggest that similar strategies maybe useful to derive potent and safe compounds from known antimicrobial

  19. In vivo antibacterial activity and pharmacological properties of the membrane-active glycopeptide antibiotic YV11455.

    PubMed

    Yarlagadda, Venkateswarlu; Konai, Mohini M; Manjunath, Goutham B; Prakash, Relekar G; Mani, Bhuvana; Paramanandham, Krishnamoorthy; Ranjan, Shome B; Ravikumar, Raju; Chakraborty, Subhankari P; Roy, Somenath; Haldar, Jayanta

    2015-06-01

    The membrane-active glycopeptide antibiotic YV11455 is a lipophilic cationic vancomycin analogue that demonstrates rapid and concentration-dependent killing of clinically relevant multidrug-resistant (MDR) Gram-positive bacteria in vitro. YV11455 was 2-fold and 54-270-fold more effective than vancomycin against clinical isolates of vancomycin-sensitive and vancomycin-resistant bacteria, respectively. In this study, the in vivo efficacy, pharmacodynamics, pharmacokinetics and acute toxicology of YV11455 were investigated. In vivo activity and pharmacodynamics were determined in the neutropenic mouse thigh infection model against meticillin-resistant Staphylococcus aureus (MRSA). YV11455 produced dose-dependent reductions in MRSA titres in thigh muscle. When administered intravenously, the 50% effective dose (ED(50)) for YV11455 against MRSA was found to be 3.3 mg/kg body weight, and titres were reduced by up to ca. 3log(10)CFU/g from pre-treatment values at a dosage of 12 mg/kg with single treatment. Single-dose pharmacokinetic studies demonstrated linear kinetics and a prolonged half-life, with an increase in drug exposure (area under the concentration-time curve) compared with vancomycin. The peak plasma concentration following an intravenous dose of 12 mg/kg was 543.5 μg/mL. Acute toxicology studies revealed that YV11455 did not cause any significant alterations in biochemical parameters or histological pictures related to major organs such as the liver and kidney at its pharmacodynamic endpoint (ED(3-log kill)). These findings collectively suggest that YV11455 could be used clinically for the treatment of infections caused by MDR Gram-positive bacteria.

  20. Antioxidant Activity, Antitumor Effect, and Antiaging Property of Proanthocyanidins Extracted from Kunlun Chrysanthemum Flowers

    PubMed Central

    Jing, Siqun; Zhang, Xiaoming

    2015-01-01

    The objective of the present study was to evaluate the antioxidant activity, antitumor effect, and antiaging property of proanthocyanidins from Kunlun Chrysanthemum flowers (PKCF) grown in Xinjiang. In vitro antioxidant experiments results showed that the total antioxidant activity and the scavenging capacity of hydroxyl radicals (•OH) and 1,1-diphenyl-2-picrylhydrazyl (DPPH•) radicals increased in a concentration-dependent manner and were stronger than those of vitamin C. To investigate the antioxidant activity of PKCF in vivo, we used serum, liver, and kidney from mouse for the measurement of superoxide dismutase (SOD), malondialdehyde (MDA), and total antioxidant capacity (T-AOC). Results indicated that PKCF had antioxidative effect in vivo which significantly improved the activity of SOD and T-AOC and decreased MDA content. To investigate the antitumor activity of PKCF, we used H22 cells, HeLa cells, and Eca-109 cells with Vero cells as control. Inhibition ratio and IC50 values were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay; PKCF showed great inhibitory activity on H22 cells and HeLa cells. We also used fruit flies as a model for analyzing the anti-aging property of PKCF. Results showed that PKCF has antiaging effect on Drosophila. Results of the present study demonstrated that PKCF could be a promising agent that may find applications in health care, medicine, and cosmetics. PMID:25628774

  1. Biological and surface-active properties of double-chain cationic amino acid-based surfactants.

    PubMed

    Greber, Katarzyna E; Dawgul, Małgorzata; Kamysz, Wojciech; Sawicki, Wiesław; Łukasiak, Jerzy

    2014-08-01

    Cationic amino acid-based surfactants were synthesized via solid phase peptide synthesis and terminal acylation of their α and ε positions with saturated fatty acids. Five new lipopeptides, N-α-acyl-N-ε-acyl lysine analogues, were obtained. Minimum inhibitory concentration and minimum bactericidal (fungicidal) concentration were determined on reference strains of bacteria and fungi to evaluate the antimicrobial activity of the lipopeptides. Toxicity to eukaryotic cells was examined via determination of the haemolytic activities. The surface-active properties of these compounds were evaluated by measuring the surface tension and formation of micelles as a function of concentration in aqueous solution. The cationic surfactants demonstrated diverse antibacterial activities dependent on the length of the fatty acid chain. Gram-negative bacteria and fungi showed a higher resistance than Gram-positive bacterial strains. It was found that the haemolytic activities were also chain length-dependent values. The surface-active properties showed a linear correlation between the alkyl chain length and the critical micelle concentration.

  2. In vitro antimicrobial activity on clinical microbial strains and antioxidant properties of Artemisia parviflora

    PubMed Central

    2012-01-01

    Background Artemisia parviflora leaf extracts were evaluated for potential antimicrobial and antioxidant properties. Antimicrobial susceptibility assay was performed against ten standard reference bacterial strains. Antioxidant activity was analyzed using the ferric thiocyanate and 2, 2-Diphenyl-1-Picrylhydrazyl (DPPH) assays. Radical scavenging activity and total phenolic content were compared. Phytochemical analyses were performed to identify the major bioactive constitution of the plant extract. Results Hexane, methanol and ethyl acetate extracts of A. parviflora leaves exhibited good activity against the microorganisms tested. The n-hexane extract of A. parviflora showed high inhibition of the growth of Pseudomonas aeruginosa, Escherichia coli and Shigella flexneri. Methanol extract showed strong radical scavenging and antioxidant activity, other extracts showed moderate antioxidant activity. The major derivatives present in the extracts are of terpenes, steroids, phenols, flavonoids, tannins and volatile oil. Conclusions The results obtained with n-hexane extract were particularly significant as it strongly inhibited the growth of P. aeruginosa, E. coli and S. flexneri. The major constituent of the n-hexane extract was identified as terpenes. Strong antioxidant activity could be observed with all the individual extracts. The antimicrobial and antioxidant property of the extracts were attributed to the secondary metabolites, terpenes and phenolic compounds present in A. parviflora and could be of considerable interest in the development of new drugs. PMID:23171441

  3. Property.

    ERIC Educational Resources Information Center

    Piele, Philip K.; Johnson, Margaret M.

    This chapter deals with 1981 cases involving disputes over property. Cases involving the detachment and attachment of land continue to dominate the property chapter with 11 cases reported, the same number summarized in last year's chapter. One case involving school board referenda raised the interesting question of whether or not a state could…

  4. Property.

    ERIC Educational Resources Information Center

    Bickel, Robert D.; Zeller, Trisha A.

    A number of cases related to property issues involving institutions of higher education are examined in this chapter. Cases discussed touch on such topics as funding for property and equipment acquisition; opposition to building construction or demolition; zoning issues; building construction and equipment contracts; and lease agreements. Current…

  5. Correlation between dielectric property by dielectrophoretic levitation and growth activity of cells exposed to electric field.

    PubMed

    Hakoda, Masaru; Hirota, Yusuke

    2013-09-01

    The purpose of this study is to develop a system analyzing cell activity by the dielectrophoresis method. Our previous studies revealed a correlation between the growth activity and dielectric property (Re[K(ω)]) of mouse hybridoma 3-2H3 cells using dielectrophoretic levitation. Furthermore, it was clarified that the differentiation activity of many stem cells could be evaluated by the Re[K(ω)] without differentiation induction. In this paper, 3-2H3 cells exposed to an alternating current (AC) electric field or a direct current (DC) electric field were cultivated, and the influence of damage by the electric field on the growth activity of the cells was examined. To evaluate the activity of the cells by measuring the Re[K(ω)], the correlation between the growth activity and the Re[K(ω)] of the cells exposed to the electric field was examined. The relations between the cell viability, growth activity, and Re[K(ω)] in the cells exposed to the AC electric field were obtained. The growth activity of the cells exposed to the AC electric field could be evaluated by the Re[K(ω)]. Furthermore, it was found that the adverse effects of the electric field on the cell viability and the growth activity were smaller in the AC electric field than the DC electric field.

  6. Entrapped elemental selenium nanoparticles affect physicochemical properties of selenium fed activated sludge.

    PubMed

    Jain, Rohan; Seder-Colomina, Marina; Jordan, Norbert; Dessi, Paolo; Cosmidis, Julie; van Hullebusch, Eric D; Weiss, Stephan; Farges, François; Lens, Piet N L

    2015-09-15

    Selenite containing wastewaters can be treated in activated sludge systems, where the total selenium is removed from the wastewater by the formation of elemental selenium nanoparticles, which are trapped in the biomass. No studies have been carried out so far on the characterization of selenium fed activated sludge flocs, which is important for the development of this novel selenium removal process. This study showed that more than 94% of the trapped selenium in activated sludge flocs is in the form of elemental selenium, both as amorphous/monoclinic selenium nanospheres and trigonal selenium nanorods. The entrapment of the elemental selenium nanoparticles in the selenium fed activated sludge flocs leads to faster settling rates, higher hydrophilicity and poorer dewaterability compared to the control activated sludge (i.e., not fed with selenite). The selenium fed activated sludge showed a less negative surface charge density as compared to the control activated sludge. The presence of trapped elemental selenium nanoparticles further affected the spatial distribution of Al and Mg in the activated sludge flocs. This study demonstrated that the formation and subsequent trapping of elemental selenium nanoparticles in the activated sludge flocs affects their physicochemical properties.

  7. Copper(I) Complexes for Thermally Activated Delayed Fluorescence: From Photophysical to Device Properties.

    PubMed

    Leitl, Markus J; Zink, Daniel M; Schinabeck, Alexander; Baumann, Thomas; Volz, Daniel; Yersin, Hartmut

    2016-06-01

    Molecules that exhibit thermally activated delayed fluorescence (TADF) represent a very promising emitter class for application in electroluminescent devices since all electrically generated excitons can be transferred into light according to the singlet harvesting mechanism. Cu(I) compounds are an important class of TADF emitters. In this contribution, we want to give a deeper insight into the photophysical properties of this material class and demonstrate how the emission properties depend on molecular and host rigidity. Moreover, we show that with molecular optimization a significant improvement of selected emission properties can be achieved. From the discussed materials, we select one specific dinuclear complex, for which the two Cu(I) centers are four-fold bridged to fabricate an organic light emitting diode (OLED). This device shows the highest efficiency (of 23 % external quantum efficiency) reported so far for OLEDs based on Cu(I) emitters. PMID:27573265

  8. Active Antifogging Property of Monolayer SiO2 Film with Bioinspired Multiscale Hierarchical Pagoda Structures.

    PubMed

    Han, Zhiwu; Mu, Zhengzhi; Li, Bo; Wang, Ze; Zhang, Junqiu; Niu, Shichao; Ren, Luquan

    2016-09-27

    Antifogging surfaces with hydrophilic or even superhydrophilic wetting behavior have received significant attention due to their ability to reduce light scattering by film-like condensation. However, a major challenge remains in achieving high-speed antifogging performance and revealing the hydrophilic-based antifogging mechanism of glass or other transparent materials under aggressive fogging conditions. Herein, with inspiration from the fog-free property of the typical Morpho menelaus terrestris butterfly (Butler, 1866) wing scales, a monolayer SiO2 film with multiscale hierarchical pagoda structures (MHPSs) based on glass substrate was designed and fabricated using an optimized biotemplate-assisted wet chemical method without any post-treatments. The biomimetic monolayer film (BMF) composed of nanoscale SiO2 3D networks displayed excellent antifogging properties, which is superior to that of the glass substrate itself. The MHPS-based BMF even kept high transmittance (∼95%) under aggressive fog conditions, and it almost instantaneously recovered to a fog-free state (<5 s). Moreover, the underlying active antifogging strategy gathering initial fog capture and final antifog together was revealed. The fogdrops spontaneously adhered on the BMF surface and rapidly spread along the MHPSs in an anisotropic way, which made the fogdrops evaporate instantaneously to attain an initial fog-free state, leading to an efficient active antifogging performance. These properties mainly benefit from the synergistic effect of both hydrophilic chemical compositions (nanoscale SiO2) and physical structures (biomimetic MHPSs) of the BMF. High-speed active antifogging performance of the glass materials enabled the retention of a high transmittance property even in humid conditions, heralding reliable optical performance in outdoor practical applications, especially in aggressive foggy environments. More importantly, the investigations in this work offer a promising way to handily

  9. Methanolic extracts of Withania somnifera leaves, fruits and roots possess antioxidant properties and antibacterial activities

    PubMed Central

    2012-01-01

    Background Withania somnifera, also known as ashwagandha, is an important herb in ayurvedic and indigenous medical systems. The present study was designed to evaluate the antioxidant and antibacterial activities of an 80% aqueous methanolic extract of W. somnifera roots (WSREt), fruits (WSFEt) and leaves (WSLEt). Methods Several assays were performed to determine the antioxidant properties of this herb including 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity, ferric reducing antioxidant power (FRAP), ferrous chelation and inhibition of β-carotene bleaching. Results The values for DPPH, FRAP, ferrous chelation and inhibition of β carotene bleaching for the three types of extracts ranged from 101.73-801.93 μg/ml, 2.26-3.29 mM Fe/kg, 0.22-0.65 mg/ml and 69.87-79.67%, respectively, indicating that W. somnifera, particularly the leaves, possesses significant antioxidant properties. The mean ascorbic acid content was 20.60-62.60 mg/100 g, and the mean anthocyanin content was 2.86-12.50 mg/100 g. Antibacterial activities were measured using the agar well diffusion method and five pathogenic Gram-negative bacteria: Escherichia coli, Salmonella typhi, Citrobacter freundii, Pseudomonas aeruginosa and Klebsiella pneumoniae. The leaf extracts displayed the highest activity against S. typhi (32.00 ± 0.75 mm zone of inhibition), whereas the lowest activity was against K. pneumoniae (19.00 ± 1.48 mm zone of inhibition). The lowest minimum inhibitory concentration value was 6.25 mg/ml, which was against S. typhi, followed by 12.5 mg/ml against E. coli. Conclusion In addition to its antioxidant properties, W. somnifera exhibited significant antibacterial activities against Gram-negative bacteria, particularly S. typhi. PMID:23039061

  10. Cellular Interaction and Toxicity Depends on Physiochemical Properties and Surface Modification of Redox Active Nanomaterials

    PubMed Central

    Dowding, Janet M.; Das, Soumen; Kumar, Amit; Dosani, Talib; McCormack, Rameech; Gupta, Ankur; Sayle, Thi X. T.; Sayle, Dean C.; von Kalm, Laurence; Seal, Sudipta; Self, William T.

    2013-01-01

    The study of the chemical and biological properties of CeO2 NPs (CNPs) has expanded recently due to its therapeutic potential, and the methods used to synthesize these materials are diverse. Moreover, conflicting reports exists regarding the toxicity of CNP. To help resolve these discrepancies, we must first determine whether CeO2 NPs made by different methods are similar or different in their physiochemical and catalytic properties. In this paper, we have synthesized several forms of CNPs using identical precursors through a wet chemical process but using different oxidizer/reducer H2O2 (CNP1), NH4OH (CNP2) or hexamethylenetetramine (HMT-CNP1). Physiochemical properties of these CeO2 NPs were extensively studied and found to be different depending on the preparation methods. Unlike CNP1 and CNP2, HMT-CNP1 were readily taken into endothelial cells and their aggregation can be visualized using light microscopy. Exposure to HMT-CNP1 also reduced cell viability (MTT) at a 10-fold lower concentration than CNP1 or CNP2. Surprisingly, exposure to HMT-CNP1 led to substantial decreases in the ATP levels. Mechanistic studies revealed that HMT-CNP1 exhibited substantial ATPase (phosphatase) activity. Though CNP2 also exhibits ATPase activity, CNP1 lacked ATPase activity. The difference in catalytic (ATPase) activity of different CeO2 NPs preparation may be due to differences in their morphology and oxygen extraction energy. These results suggest the combination of increased uptake and ATPase activity of HMT-CNP1 may underlie the biomechanism of the toxicity of this preparation of CNPs, and may suggest ATPase activity should be considered when synthesizing CNPs for use in biomedical applications. PMID:23668322

  11. The mechanical and tribological properties of UHMWPE loaded ALN after mechanical activation for joint replacements.

    PubMed

    Gong, Kemeng; Qu, Shuxin; Liu, Yumei; Wang, Jing; Zhang, Yongchao; Jiang, Chongxi; Shen, Ru

    2016-08-01

    Ultra-high molecular weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN) has tremendous potential as an orthopeadic biomaterial for joint replacements. However, poor mechanical and tribological properties of UHMWPE-ALN are still obstacle for further application. The purpose of this study was to investigate the effect and mechanism of mechanical activation on mechanical and tribological properties of 1wt% ALN-loaded UHMWPE (UHMWPE-ALN-ma). In this study, tensile test, small punch test and reciprocating sliding wear test were applied to characterize the mechanical and tribological properties of UHMWPE-ALN-ma. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were employed to characterize UHMWPE-ALN-ma. Tensile test and small punch test showed that Young׳s modulus, tensile strength and work-to-failure (WTF) of UHMWPE-ALN-ma increased significantly compared to those of UHMWPE-ALN. The friction coefficients and wear factors of UHMWPE-ALN-ma both decreased significantly compared to those of UHMWPE-ALN. Mechanical activation obviously reduced type 1 (void) and type 2 (the disconnected and dislocated machining marks) fusion defects of UHMWPE-ALN-ma, which were revealed by SEM images of freeze fracture surfaces after etching and lateral surfaces of specimens after extension to fracture, respectively. It was attributed to peeled-off layers and chain scission of molecular chains of UHMWPE particles after mechanical activation, which were revealed by SEM images and FTIR spectra of UHMWPE-ALN-ma and UHMWPE-ALN, respectively. Moreover, EDS spectra revealed the more homogeneous distribution of ALN in UHMWPE-ALN-ma compared to that of UHMWPE-ALN. The present results showed that mechanical activation was a potential strategy to improve mechanical and tribological properties of UHMWPE-ALN-ma as an orthopeadic biomaterial for joint replacements. PMID:27104932

  12. The mechanical and tribological properties of UHMWPE loaded ALN after mechanical activation for joint replacements.

    PubMed

    Gong, Kemeng; Qu, Shuxin; Liu, Yumei; Wang, Jing; Zhang, Yongchao; Jiang, Chongxi; Shen, Ru

    2016-08-01

    Ultra-high molecular weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN) has tremendous potential as an orthopeadic biomaterial for joint replacements. However, poor mechanical and tribological properties of UHMWPE-ALN are still obstacle for further application. The purpose of this study was to investigate the effect and mechanism of mechanical activation on mechanical and tribological properties of 1wt% ALN-loaded UHMWPE (UHMWPE-ALN-ma). In this study, tensile test, small punch test and reciprocating sliding wear test were applied to characterize the mechanical and tribological properties of UHMWPE-ALN-ma. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were employed to characterize UHMWPE-ALN-ma. Tensile test and small punch test showed that Young׳s modulus, tensile strength and work-to-failure (WTF) of UHMWPE-ALN-ma increased significantly compared to those of UHMWPE-ALN. The friction coefficients and wear factors of UHMWPE-ALN-ma both decreased significantly compared to those of UHMWPE-ALN. Mechanical activation obviously reduced type 1 (void) and type 2 (the disconnected and dislocated machining marks) fusion defects of UHMWPE-ALN-ma, which were revealed by SEM images of freeze fracture surfaces after etching and lateral surfaces of specimens after extension to fracture, respectively. It was attributed to peeled-off layers and chain scission of molecular chains of UHMWPE particles after mechanical activation, which were revealed by SEM images and FTIR spectra of UHMWPE-ALN-ma and UHMWPE-ALN, respectively. Moreover, EDS spectra revealed the more homogeneous distribution of ALN in UHMWPE-ALN-ma compared to that of UHMWPE-ALN. The present results showed that mechanical activation was a potential strategy to improve mechanical and tribological properties of UHMWPE-ALN-ma as an orthopeadic biomaterial for joint replacements.

  13. Physical Properties, Antioxidant and Antimicrobial Activity of Chitosan Films Containing Carvacrol and Pomegranate Peel Extract.

    PubMed

    Yuan, Gaofeng; Lv, Hua; Yang, Bingjie; Chen, Xiaoe; Sun, Haiyan

    2015-01-01

    Chitosan-based active films were developed by incorporation of carvacrol (10 g/L), pomegranate peel extract (PPE, 10 g/L) and carvacrol + PPE (10 g/L of each) and their physical, antioxidant and antimicrobial properties were investigated. Incorporation of carvacrol and carvacrol + PPE into the films significantly decreased the water vapor permeability, tensile strength and percentage of elongation at break. Incorporation of carvacrol, PPE and carvacrol + PPE into the films decreased the transparency, but significantly increased the total phenol content and antioxidant activity. All the films, with the exception of PPE-incorporated film, exhibited antibacterial activity against Escherichia coli and Staphylococcus aureus. In addition, the antibacterial activity against Staphylococcus aureus of the film incorporated with carvacrol + PPE was moderately higher than that incorporated with carvacrol or PPE alone, suggesting a synergistic action between carvacrol and PPE. PMID:26083037

  14. Structural properties of composites of polyvinylidene fluoride and mechanically activated BaTiO3 particles

    NASA Astrophysics Data System (ADS)

    Pavlović, V. P.; Pavlović, V. B.; Vlahović, B.; Božanić, D. K.; Pajović, J. D.; Dojčilović, R.; Djoković, V.

    2013-11-01

    Nanocomposites of electroactive ceramics and ferroelectric polymers exploit favorable features of the matrix polymer and the nanostructured filler to produce new functional materials for pressure and IR sensors. In this study, the influence of mechanical activation of barium titanate (BaTiO3) particles on the structural properties of BaTiO3/polyvinylidene fluoride (PVDF) nanocomposites was investigated. Nanocomposite films were prepared by the solution casting method and characterized by scanning electron microscopy, x-ray diffraction and Raman spectroscopy. It was found that mechanically activated fillers promote the formation of a ferroelectric β-phase during crystallization of PVDF.

  15. A new class of conjugated strigolactone analogues with fluorescent properties: synthesis and biological activity.

    PubMed

    Bhattacharya, Chaitali; Bonfante, Paola; Deagostino, Annamaria; Kapulnik, Yoram; Larini, Paolo; Occhiato, Ernesto G; Prandi, Cristina; Venturello, Paolo

    2009-09-01

    A new class of strigolactone analogues has been synthesized. They differ from known molecules, both of natural and synthetic origin, in two main features. The conjugated system extends from the enol ether bridge to the A ring, the B ring is a heterocycle while the C ring is a cyclic ketone instead of a gamma-lactone. The key step of the synthesis is a Nazarov cyclization on activated substrates. Bioassays using Orobanche seeds have revealed that all the molecules strongly stimulate germination; in particular the oxygen containing analogues are the most active. Interestingly, some of the new molecules show fluorescent properties. PMID:19675895

  16. Structural and mechanical properties of welded joints of reduced activation martensitic steels

    NASA Astrophysics Data System (ADS)

    Filacchioni, G.; Montanari, R.; Tata, M. E.; Pilloni, L.

    2002-12-01

    Gas tungsten arc welding and electron beam welding methods were used to realise welding pools on plates of reduced activation martensitic steels. Structural and mechanical features of these simulated joints have been investigated in as-welded and post-welding heat-treated conditions. The research allowed to assess how each welding technique affects the original mechanical properties of materials and to find suitable post-welding heat treatments. This paper reports results from experimental activities on BATMAN II and F82H mod. steels carried out in the frame of the European Blanket Project - Structural Materials Program.

  17. Triterpenoid resinous metabolites from the genus Boswellia: pharmacological activities and potential species-identifying properties

    PubMed Central

    2013-01-01

    The resinous metabolites commonly known as frankincense or olibanum are produced by trees of the genus Boswellia and have attracted increasing popularity in Western countries in the last decade for their various pharmacological activities. This review described the pharmacological specific details mainly on anti-inflammatory, anti-carcinogenic, anti-bacterial and apoptosis-regulating activities of individual triterpenoid together with the relevant mechanism. In addition, species-characterizing triterpenic markers with the methods for their detection, bioavailability, safety and other significant properties were reviewed for further research. PMID:24028654

  18. Aqueous phase adsorption of different sized molecules on activated carbon fibers: Effect of textural properties.

    PubMed

    Prajapati, Yogendra N; Bhaduri, Bhaskar; Joshi, Harish C; Srivastava, Anurag; Verma, Nishith

    2016-07-01

    The effect that the textural properties of rayon-based activated carbon fibers (ACFs), such as the BET surface area and pore size distribution (PSD), have on the adsorption of differently sized molecules, namely, brilliant yellow (BY), methyl orange (MO) and phenol (PH), was investigated in the aqueous phase. ACF samples with different BET areas and PSDs were produced by steam-activating carbonized fibers for different activation times (0.25, 0.5, and 1 h). The samples activated for 0.25 h were predominantly microporous, whereas those activated for relatively longer times contained hierarchical micro-mesopores. The adsorption capacities of the ACFs for the adsorbate increased with increasing BET surface area and pore volume, and ranged from 51 to 1306 mg/g depending on the textural properties of the ACFs and adsorbate size. The adsorption capacities of the hierarchical ACF samples followed the order BY > MO > PH. Interestingly, the number of molecules adsorbed by the ACFs followed the reverse order: PH > MO > BY. This anomaly was attributed to the increasing molecular weight of the PH, MO and BY molecules. The equilibrium adsorption data were described using the Langmuir isotherm. This study shows that suitable textural modifications to ACFs are required for the efficient aqueous phase removal of an adsorbate. PMID:27107386

  19. Aqueous phase adsorption of different sized molecules on activated carbon fibers: Effect of textural properties.

    PubMed

    Prajapati, Yogendra N; Bhaduri, Bhaskar; Joshi, Harish C; Srivastava, Anurag; Verma, Nishith

    2016-07-01

    The effect that the textural properties of rayon-based activated carbon fibers (ACFs), such as the BET surface area and pore size distribution (PSD), have on the adsorption of differently sized molecules, namely, brilliant yellow (BY), methyl orange (MO) and phenol (PH), was investigated in the aqueous phase. ACF samples with different BET areas and PSDs were produced by steam-activating carbonized fibers for different activation times (0.25, 0.5, and 1 h). The samples activated for 0.25 h were predominantly microporous, whereas those activated for relatively longer times contained hierarchical micro-mesopores. The adsorption capacities of the ACFs for the adsorbate increased with increasing BET surface area and pore volume, and ranged from 51 to 1306 mg/g depending on the textural properties of the ACFs and adsorbate size. The adsorption capacities of the hierarchical ACF samples followed the order BY > MO > PH. Interestingly, the number of molecules adsorbed by the ACFs followed the reverse order: PH > MO > BY. This anomaly was attributed to the increasing molecular weight of the PH, MO and BY molecules. The equilibrium adsorption data were described using the Langmuir isotherm. This study shows that suitable textural modifications to ACFs are required for the efficient aqueous phase removal of an adsorbate.

  20. Influence of Physicochemical Properties of Silver Nanoparticles on Mast Cell Activation and Degranulation

    PubMed Central

    Aldossari, Abdullah A.; Shannahan, Jonathan H.; Podila, Ramakrishna; Brown, Jared M.

    2014-01-01

    Silver nanoparticles (AgNPs) are increasingly being incorporated into products for their antimicrobial properties. This has resulted in increased human exposures and the possibility of adverse health effects. Mast cells orchestrate allergic immune responses through degranulation and release of pre-formed mediators. Little data exists on understanding interactions of AgNPs with mast cells and the properties that influence activation and degranulation. Using bone marrow-derived mast cells and AgNPs of varying physicochemical properties we tested the hypothesis that AgNP physicochemical properties influence mast cell degranulation and osteopontin production. AgNPs evaluated included spherical 20 nm and 110 nm suspended in either polyvinylpyrrolidone (PVP) or citrate, Ag plates suspended in PVP of diameters between 40–60 nm or 100–130 nm, and Ag nanowires suspended in PVP with thicknesses <100 nm and length up to 2 microns. Mast cell responses were found to be dependent on the physicochemical properties of the AgNP. Further, we determined a role for scavenger receptor B1 in AgNP-induced mast cell responses. Mast cell degranulation was not dependent on AgNP dissolution but was prevented by tyrosine kinsase inhibitor pretreatment. This study suggests that exposure to AgNPs may elicit adverse mast cell responses that could contribute to the initiation or exacerbation of allergic disease. PMID:25458489

  1. Active Pharmaceutical Ingredients: Prediction of Physical-Chemical Properties from First Principles

    NASA Astrophysics Data System (ADS)

    Valenzano, Loredana

    2013-03-01

    Polymorphism in active pharmaceutical ingredients (APIs) plays a crucial role both for medical and intellectual property concerns but despite ongoing efforts, experimental and computational investigations of the existence and the physical-chemical properties of the same compound in different forms is still an open question.While comparison between computed and experimental values for properties derived from differences between states is often promising (such as bulk modulus), results are disappointing for absolute values (such as density). Quantum mechanical computational methods describe the systems at 0K, experimentally properties are often evaluated at room temperature. Therefore it is not surprising that results determined from first principles dramatically differ from those obtained experimentally. By applying a quantum mechanical periodic approach that takes into account long range London dispersion forces fitted for solid materials, and by imposing different cell volumes corresponding to different thermodynamic conditions, we show how results from calculations at 0K (structures, vibrational spectra, elastic constants) may be compared to experimental values at higher temperatures, helping to foster a stronger linkage between computational and experimental work on systems such as APIs. Where experimental results are not available, our work represents an innovative approach in addressing the properties of APIs. Our results can also serve as foundation for the developing of new force fields to be adopted within a multi-scale computational approach.

  2. Biophysical properties of Saccharomyces cerevisiae and their relationship with HOG pathway activation.

    PubMed

    Schaber, Jörg; Adrover, Miquel Angel; Eriksson, Emma; Pelet, Serge; Petelenz-Kurdziel, Elzbieta; Klein, Dagmara; Posas, Francesc; Goksör, Mattias; Peter, Mathias; Hohmann, Stefan; Klipp, Edda

    2010-10-01

    Parameterized models of biophysical and mechanical cell properties are important for predictive mathematical modeling of cellular processes. The concepts of turgor, cell wall elasticity, osmotically active volume, and intracellular osmolarity have been investigated for decades, but a consistent rigorous parameterization of these concepts is lacking. Here, we subjected several data sets of minimum volume measurements in yeast obtained after hyper-osmotic shock to a thermodynamic modeling framework. We estimated parameters for several relevant biophysical cell properties and tested alternative hypotheses about these concepts using a model discrimination approach. In accordance with previous reports, we estimated an average initial turgor of 0.6 ± 0.2 MPa and found that turgor becomes negligible at a relative volume of 93.3 ± 6.3% corresponding to an osmotic shock of 0.4 ± 0.2 Osm/l. At high stress levels (4 Osm/l), plasmolysis may occur. We found that the volumetric elastic modulus, a measure of cell wall elasticity, is 14.3 ± 10.4 MPa. Our model discrimination analysis suggests that other thermodynamic quantities affecting the intracellular water potential, for example the matrix potential, can be neglected under physiological conditions. The parameterized turgor models showed that activation of the osmosensing high osmolarity glycerol (HOG) signaling pathway correlates with turgor loss in a 1:1 relationship. This finding suggests that mechanical properties of the membrane trigger HOG pathway activation, which can be represented and quantitatively modeled by turgor. PMID:20563574

  3. Synthesis, Surface Active Properties and Cytotoxicity of Sodium N-Acyl Prolines.

    PubMed

    Sreenu, Madhumanchi; Narayana Prasad, Rachapudi Badari; Sujitha, Pombala; Kumar, Chityal Ganesh

    2015-01-01

    Sodium N-acyl prolines (NaNAPro) were synthesized using mixture of fatty acids obtained from coconut, palm, karanja, Sterculia foetida and high oleic sunflower oils via Schotten-Baumann reaction in 58-75% yields to study the synergetic effect of mixture of hydrophobic fatty acyl functionalities like saturation, unsaturation and cyclopropene fatty acids with different chain lengths and aliphatic hetero cyclic proline head group on their surface and cytotoxicity activities. The products were characterized by chromatographic and spectral techniques. The synthesized products were evaluated for their surface active properties such as surface tension, wetting power, foaming characteristics, emulsion stability, calcium tolerance, critical micelle concentration (CMC) and thermodynamic properties. The results revealed that all the products exhibited superior surface active properties like CMC, calcium tolerance and emulsion stability as compared to the standard surfactant, sodium lauryl sulphate (SLS). In addition, palm, Sterculia foetida and high oleic sunflower fatty N-acyl prolines exhibited promising cytotoxicity against different tumor cell lines. PMID:26521810

  4. Co-Crystals: A Novel Approach to Modify Physicochemical Properties of Active Pharmaceutical Ingredients

    PubMed Central

    Yadav, A. V.; Shete, A. S.; Dabke, A. P.; Kulkarni, P. V.; Sakhare, S. S.

    2009-01-01

    Crystal form can be crucial to the performance of a dosage form. This is especially true for compounds that have intrinsic barriers to drug delivery, such as low aqueous solubility, slow dissolution in gastrointestinal media, low permeability and first-pass metabolism. The nature of the physical form and formulation tends to exhibit the greatest effect on bioavailability parameters of water insoluble compounds that need to be given orally in high doses. An alternative approach available for the enhancement of drug solubility, dissolution and bioavailability is through the application of crystal engineering of co-crystals. The physicochemical properties of the active pharmaceutical ingredients and the bulk material properties can be modified, whilst maintaining the intrinsic activity of the drug molecule. This article covers the advantages of co-crystals over salts, solvates (hydrates), solid dispersions and polymorphs, mechanism of formation of co-crystals, methods of preparation of co-crystals and application of co-crystals to modify physicochemical characteristics of active pharmaceutical ingredients along with the case studies. The intellectual property implications of creating co-crystals are also highly relevant. PMID:20502540

  5. Antimicrobial activity against Shigella sonnei and probiotic properties of wild lactobacilli from fermented food.

    PubMed

    Zhang, Yingchun; Zhang, Lanwei; Du, Ming; Yi, Huaxi; Guo, Chunfeng; Tuo, Yanfeng; Han, Xue; Li, Jingyan; Zhang, Lili; Yang, Lin

    2011-12-20

    Four lactobacilli strains (Lactobacillus paracasei subp. paracasei M5-L, Lactobacillus rhamnosus J10-L, Lactobacillus casei Q8-L and L. rhamnosus GG (LGG), were systematically assessed for the production of antimicrobial substances active towards Shigella sonnei, Escherichia coli and Salmonella typhimurium. Agar-well assay showed that the four lactobacilli strains displayed strong antibacterial activity towards S. sonnei. The nature of antimicrobial substances was also investigated and shown to be dependent on the production of organic acids, in particular the lactic acid. Time-kill assay showed that the viability of the S. sonnei was decreased by 2.7-3.6logCFU/ml after contact with CFCS (cell-free culture supernatants) of four lactobacilli for 2h, which confirmed the result of the agar-well assay. Further analysis of the organic acid composition in the CFCS revealed that the content of lactic acid range from 227 to 293mM. In addition, the aggregations properties, adherence properties and tolerance to simulated gastrointestinal conditions were also investigated in vitro tests. The result suggested that the M5-L, J10-L and Q8-L strains possess desirable antimicrobial activity towards S. sonnei and probiotic properties as LGG and could be potentially used as novel probiotic strains in the food industry. PMID:21466951

  6. Potato tuber cytokinin oxidase/dehydrogenase genes: biochemical properties, activity, and expression during tuber dormancy progression.

    PubMed

    Suttle, Jeffrey C; Huckle, Linda L; Lu, Shunwen; Knauber, Donna C

    2014-03-15

    The enzymatic and biochemical properties of the proteins encoded by five potato cytokinin oxidase/dehydrogenase (CKX)-like genes functionally expressed in yeast and the effects of tuber dormancy progression on StCKX expression and cytokinin metabolism were examined in lateral buds isolated from field-grown tubers. All five putative StCKX genes encoded proteins with in vitro CKX activity. All five enzymes were maximally active at neutral to slightly alkaline pH with 2,6-dichloro-indophenol as the electron acceptor. In silico analyses indicated that four proteins were likely secreted. Substrate dependence of two of the most active enzymes varied; one exhibiting greater activity with isopentenyl-type cytokinins while the other was maximally active with cis-zeatin as a substrate. [(3)H]-isopentenyl-adenosine was readily metabolized by excised tuber buds to adenine/adenosine demonstrating that CKX was active in planta. There was no change in apparent in planta CKX activity during either natural or chemically forced dormancy progression. Similarly although expression of individual StCKX genes varied modestly during tuber dormancy, there was no clear correlation between StCKX gene expression and tuber dormancy status. Thus although CKX gene expression and enzyme activity are present in potato tuber buds throughout dormancy, they do not appear to play a significant role in the regulation of cytokinin content during tuber dormancy progression.

  7. Potato tuber cytokinin oxidase/dehydrogenase genes: biochemical properties, activity, and expression during tuber dormancy progression.

    PubMed

    Suttle, Jeffrey C; Huckle, Linda L; Lu, Shunwen; Knauber, Donna C

    2014-03-15

    The enzymatic and biochemical properties of the proteins encoded by five potato cytokinin oxidase/dehydrogenase (CKX)-like genes functionally expressed in yeast and the effects of tuber dormancy progression on StCKX expression and cytokinin metabolism were examined in lateral buds isolated from field-grown tubers. All five putative StCKX genes encoded proteins with in vitro CKX activity. All five enzymes were maximally active at neutral to slightly alkaline pH with 2,6-dichloro-indophenol as the electron acceptor. In silico analyses indicated that four proteins were likely secreted. Substrate dependence of two of the most active enzymes varied; one exhibiting greater activity with isopentenyl-type cytokinins while the other was maximally active with cis-zeatin as a substrate. [(3)H]-isopentenyl-adenosine was readily metabolized by excised tuber buds to adenine/adenosine demonstrating that CKX was active in planta. There was no change in apparent in planta CKX activity during either natural or chemically forced dormancy progression. Similarly although expression of individual StCKX genes varied modestly during tuber dormancy, there was no clear correlation between StCKX gene expression and tuber dormancy status. Thus although CKX gene expression and enzyme activity are present in potato tuber buds throughout dormancy, they do not appear to play a significant role in the regulation of cytokinin content during tuber dormancy progression. PMID:24594397

  8. Antioxidant Property of Jobelyn as the Possible Mechanism Underlying its Anti-amnesic Activity in Rodents

    PubMed Central

    Umukoro, Solomon; Ugbomah, Adaeze; Aderibigbe, Adegbuyi; Omogbiya, Adrian

    2013-01-01

    Introduction Amnesia or loss of memory is the cardinal hallmark of Alzheimer's disease (AD), a progressive neurodegenerative disorder associated with ageing process. Although, AD had been discovered over a century ago, drugs which could cure or halt the progression of the disease are yet to see the light of the day. However, there has been a growing interest in the use of phytomedicines with multipronged mechanisms of action that could target various aspects of the pathologies of AD. Jobelyn (JB) is a potent antioxidant African polyherbal formulation with active components that have been acclaimed to show neuroprotection. This investigation was carried out to evaluate whether JB has anti-amnesic and antioxidant activities. Methods The alteration of alternation behavior in the Y-maze paradigm was utilized as the test for memory function in mice. The effect of JB on acetylcholinesterase (AChE) activity, malondialdehyde (MDA) level and the concentrations of glutathione (GSH) in the frontal cortex and hippocampus were assessed in rats as means of providing insight into the mechanism underlying its anti-amnesic activity. The animals were given JB (1, 2.5 or 5mg/kg, i.p.) daily for 7 days before the biochemical assays or test for memory functions were carried out. Results JB was found to produce a significant increase in the level of alternation behavior compared with the control, suggesting anti-amnesic activity. Also, JB reversed the memory impairment induced by scopolamine, which further indicates anti-amnesic property. Furthermore, JB demonstrated a significant inhibition of MDA formation in the frontal cortex and hippocampus of rats, indicating antioxidant property. In addition, it increased the defense armory of the brain tissues, as it significantly increased the concentrations of GSH in the frontal cortex and hippocampus of rats. However, JB did not demonstrate any inhibitory effect against AChE activity in the frontal cortex and hippocampus of rats in comparison

  9. Antioxidant activities and functional properties of protein and peptide fractions isolated from salted herring brine.

    PubMed

    Taheri, Ali; Sabeena Farvin, K H; Jacobsen, Charlotte; Baron, Caroline P

    2014-01-01

    In the present study proteins isolated from herring brine, which is a by-product of marinated herring production were evaluated for their functional properties and antioxidant activity. Herring brine was collected from the local herring industry and proteins were precipitated by adjusting the pH to 4.5 and the obtained supernatant was further fractionated by using ultrafiltration membranes with molecular weight cut offs of 50, 10 and 1kDa. The obtained >50kDa, 50-10kDa, 10-1kDa fractions and pH precipitated fraction were studied for their functional properties and antioxidant activity. Functional properties revealed that >50kDa polypeptides showed good emulsion activity index when compared to the other fractions. However all fractions had low emulsion stability index. The pH precipitated fraction showed the highest foaming capacity and stability at pH 10. The 50-10kDa and 10-1kDa peptide fractions showed good radical scavenging activity and reducing power at a concentration of 0.5mg protein/ml. All the fractions demonstrated low iron chelating activity and did not inhibit oxidation in a soybean phosphatidylcholine liposome model system. However all the fractions were to some extent able to delay iron catalyzed lipid oxidation in 5% fish oil in water emulsions and the 10-50kDa fraction was the best. These results show the potential of proteins and peptide fractions recovered from waste water from the herring industry as source of natural antioxidants for use in food products.

  10. Chromospheric activity properties and search for subdwarfs and extreme subdwarfs based on LAMOST stellar spectral survey

    NASA Astrophysics Data System (ADS)

    Zhang, Liyun; Pi, Qingfeng; Han, Xianming L.; Shi, Jianrong; Wang, Daimei; Luo, Ali; Zhang, Yong; Hou, Yonghui; Wang, Yuefei

    2016-04-01

    Big data obtained from a stellar spectroscopic survey carried out using the Large Sky Area Multi-object Fiber Spectroscopic Telescope (LAMOST, also known as Guo Shou Jing telescope) provide important information for studying chromospheric activity, variability of chromospheric activity, and chromospheric statistical properties, and for searching subdwarfs and extreme subdwarfs. Using as chromospheric activity indicator the Hα line, we detected 6391 active M stars among the 99741 stars in the M-star catalogue of the LAMOST survey. We also obtained the relationship between the fraction of active stars and the spectral types, which is consistent to previous results. We also studied the effects of activity on broadband photometric colors, and we did not see significant differences between active and inactive M stars. Using as spectroscopic molecular indicators the CaH123 and TiO5 lines, we found 1288 subdwarfs (including 120 active subdwarfs). We also found 15 extreme subdwarf (2 active extreme subdwarf) candidates. Our subdwarf candidates are slightly redder by about 0.05 mag in g-r compared with dwarfs using the g-r and r-i, and g-r and i-z color diagrams. Using our active M-star catalogue, we found that 898 stars exhibited Hα emission in at least two exposures (170 of them in at least three exposures). Among these 170 stars, 163 of them show variability in Hα emission on long timescales (more than 2.5 h). Furthermore, 34 stars show variability over short timescales (less than 2.5 h), and 29 actives show variability over both short and long time scales.

  11. Optically active substituted polyacetylene@carbon nanotube hybrids: Preparation, characterization and infrared emissivity property study

    SciTech Connect

    Bu, Xiaohai; Zhou, Yuming Zhang, Tao; Wang, Yongjuan; Zhang, Zewu; He, Man

    2014-08-15

    Optically active substituted polyacetylene@multiwalled carbon nanotubes (SPA@MWCNTs) nanohybrids were fabricated by wrapping helical SPA copolymers onto the surface of modified nanotubes through ester bonding linkage. SPA copolymer based on chiral phenylalanine and serine was pre-polymerized by a rhodium zwitterion catalyst in THF, and evidently proved to possess strong optical activity and adopt a predominately one-handed helical conformation. Various characterizations including Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) demonstrated that the SPA had been covalently grafted onto the nanotubes without destroying their original graphite structure. The wrapped SPA was found to exhibit an enhancement in thermal stability and still maintained considerable optical activity after grafting. The infrared emissivity property of the nanohybrids at 8–14 μm was investigated in addition. The results indicated that the SPA@MWCNTs hybrid matrix could possess a much lower infrared emissivity value (ε=0.707) than raw MWCNTs, which might be due to synergistic effect of the unique helical conformation of optically active SPA and strengthened interfacial interaction between the organic polymers and inorganic nanoparticles. - Graphical abstract: Optically active SPA@MWCNTs nanohybrids with low infrared emissivity. - Highlights: • Synthesis of optically active SPA copolymer derived from serine and phenylalanine. • Preparation and characterization of optically active SPA@MWCNTs nanohybrids. • Application study of the SPA@MWCNTs nanohybrids (ε=0.707) in lowering the infrared emissivity.

  12. SteamTablesGrid: An ActiveX control for thermodynamic properties of pure water

    NASA Astrophysics Data System (ADS)

    Verma, Mahendra P.

    2011-04-01

    An ActiveX control, steam tables grid ( StmTblGrd) to speed up the calculation of the thermodynamic properties of pure water is developed. First, it creates a grid (matrix) for a specified range of temperature (e.g. 400-600 K with 40 segments) and pressure (e.g. 100,000-20,000,000 Pa with 40 segments). Using the ActiveX component SteamTables, the values of selected properties of water for each element (nodal point) of the 41×41 matrix are calculated. The created grid can be saved in a file for its reuse. A linear interpolation within an individual phase, vapor or liquid is implemented to calculate the properties at a given value of temperature and pressure. A demonstration program to illustrate the functionality of StmTblGrd is written in Visual Basic 6.0. Similarly, a methodology is presented to explain the use of StmTblGrd in MS-Excel 2007. In an Excel worksheet, the enthalpy of 1000 random datasets for temperature and pressure is calculated using StmTblGrd and SteamTables. The uncertainty in the enthalpy calculated with StmTblGrd is within ±0.03%. The calculations were performed on a personal computer that has a "Pentium(R) 4 CPU 3.2 GHz, RAM 1.0 GB" processor and Windows XP. The total execution time for the calculation with StmTblGrd was 0.3 s, while it was 60.0 s for SteamTables. Thus, the ActiveX control approach is reliable, accurate and efficient for the numerical simulation of complex systems that demand the thermodynamic properties of water at several values of temperature and pressure like steam flow in a geothermal pipeline network.

  13. Evaluation of the Antioxidant Activities and Tyrosinase Inhibitory Property from Mycelium Culture Extracts

    PubMed Central

    Park, Ki Moon; Kwon, Kyung Min; Lee, Seung Ho

    2015-01-01

    Since mushrooms have many bioactive components, they have been used as components in folk medicine. Because mycelium has an advantage when it comes to large-scale production, this study aimed to evaluate the antioxidant properties and anti-tyrosinase activity from 55 mycelia in culture media. Relatively high 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity was detected from the ethanol extract of culture media including mycelium (EECiM) of Morchella esculenta var. esculenta (MEVE), Auricularia polytricha (APO), Tremella aurantia (TAU), Volvariella bombycina (VBO), and Oudemansiella sp. (Osp), which also showed strong reducing power and inhibitory activity in relation to the thiobarbituric acid (TBA) value. On the other hand, relatively high tyrosinase inhibitory activity was detected in Inonotus mikadoi (IMI), Coriolus versicolor (CVE), Volvariella volvacea (VVO), Panellus serotinus (PSE), Auricularia auricula (AAU), and Fomitopsis sp. (Fsp). Interestingly, the APO EECiM exhibited the highest DPPH radical scavenging rate (77.5 ± 4.3%) and reducing power (1.18 ± 0.041), while the highest inhibitory power of the TBA value and antityrosinase activity were detected in that of TAU (64.5 ± 4.1%) and IMI (46.0 ± 7.5%), respectively. Overall, our study suggested potential candidates for EECiMs that exhibited powerful antioxidant and tyrosinase inhibitory properties and might be used as natural antioxidant tyrosinase inhibitor. PMID:26345142

  14. An optimized molecular inclusion complex of diferuloylmethane: enhanced physical properties and biological activity

    PubMed Central

    Tan, Qunyou; Li, Yi; Wu, Jianyong; Mei, Hu; Zhao, Chunjing; Zhang, Jingqing

    2012-01-01

    Objective The purpose of this study was to explore and evaluate the enhanced physical properties and biological activity of a molecular inclusion complex (MICDH) comprising diferuloylmethane (DFM) and hydroxypropyl-β-cyclodextrin. Methods The preparation conditions of MICDH were optimized using an orthogonal experimental design. The solubility, in vitro release and model fitting, microscopic morphology, molecular structure simulation, anti-lung cancer activity, and action mechanism of MICDH were evaluated. Results The solubility of DFM was improved 4400-fold upon complexation with hydroxypropyl-β-cyclodextrin. The release rate of DFM was significantly higher from MICDH than from free DFM. MICDH exhibited higher antitumor activity against human lung adenocarcinoma A549 cells than free DFM. More cells were arrested in the S/G2 phase of the cell cycle or were induced to undergo apoptosis when treated with MICDH than when treated with free DFM. Furthermore, increased reactive oxygen species and intracellular calcium ion levels and decreased mitochondrial membrane potential were observed in cells treated with MICDH. Conclusion MICDH markedly improved the physical properties and antitumor activity of DFM. MICDH may prove to be a preferred alternative to free DFM as a formulation for DFM delivery in lung cancer treatment. PMID:23091376

  15. The in vitro activity of vaginal Lactobacillus with probiotic properties against Candida.

    PubMed

    Strus, Magdalena; Kucharska, Agnieszka; Kukla, Grazyna; Brzychczy-Włoch, Monika; Maresz, Katarzyna; Heczko, Piotr B

    2005-06-01

    Lactobacilli, the predominant vaginal microorganisms in healthy premenopausal women, control other members of the vaginal microflora and thus protect against bacterial vaginosis and urinary tract infections. It has been claimed that some lactobacilli are also protective against Candida vaginitis. Little is known, however, about the mechanisms by which these lactobacilli can control vaginal populations of Candida and prevent vaginitis. To address this question, vaginal Lactobacillus strains with known antagonistic properties against bacteria were tested for their cell surface properties, adhesion to vaginal cell lines in vitro and antagonistic activities against Candida. A small proportion of the lactobacilli tested adhered strongly to cultured vaginal epithelial cells and inhibited growth of Candida albicans but not of C. pseudotropicalis. This anticandidal activity was in some Lactobacillus strains related to hydrogen peroxide (H2O2) production, but catalase treatment did not suppress this activity in other Lactobacillus strains, suggesting alternative mechanism(s). Moreover, tested vaginal Candida strains were resistant to relatively high concentrations of H2O2 that markedly exceeded those produced by even the most active Lactobacillus strains.

  16. Luminescence properties of europium?terbium double activated calcium tungstate phosphor*1

    NASA Astrophysics Data System (ADS)

    Nazarov, M. V.; Jeon, D. Y.; Kang, J. H.; Popovici, E.-J.; Muresan, L.-E.; Zamoryanskaya, M. V.; Tsukerblat, B. S.

    2004-08-01

    Double incorporation of Eu 3+ and Tb 3+ ions into a CaWO 4 crystalline lattice modifies the luminescence spectrum due to the formation of new emission centers. Depending on the activators concentration and nature, as well as on the interaction between the activators themselves, the luminescence color can be varied within the entire range of the visible spectrum. Variable luminescence was obtained when CaWO 4:Eu,Tb phosphors with 0-5 mol% activator ions were exposed to relatively low excitation energies as UV (365 and 254 nm). Under high energy excitation such as VUV (147 nm) radiation or electron beam, white light has been observed. This material with controlled properties seems to be promising for the applications in fluorescent lamps, colored lightning for advertisement industries, and other optoelectronic devices.

  17. Effect of wall material on the antioxidant activity and physicochemical properties of Rubus fruticosus juice microcapsules.

    PubMed

    Díaz, Dafne I; Beristain, Cesar I; Azuara, Ebner; Luna, Guadalupe; Jimenez, Maribel

    2015-01-01

    Blackberry (Rubus fruticosus) juice possesses compounds with antioxidant activity, which can be protected by different biopolymers used in the microencapsulation. Therefore, the effects of cell wall material including maltodextrin (MD), Arabic gum (GA) and whey protein concentrate (WPC) were evaluated on the physicochemical and antioxidant properties of encapsulated blackberries using a spray-drying technique. Anthocyanin concentration, polymeric colour, total polyphenols, radical scavenging activity of the 1,1-diphenyl-2-picrilhydrazil radical, reducing power and the stability at different storage conditions were evaluated. GA and MD conferred a similar protection to the antioxidant compounds when the microcapsules were stored at low water activities (aw < 0.515) in contrast to at a high moisture content (aw > 0.902), whereas WPC presented a high protection. Therefore, the selection of the best wall material for blackberry juice encapsulation depends of the conditions of storage of the powder.

  18. [Effects of nitrogen addition on soil physico-chemical properties and enzyme activities in desertified steppe].

    PubMed

    Su, Jie-Qiong; Li, Xin-Rong; Bao, Jing-Ting

    2014-03-01

    To investigate the impacts of nitrogen (N) enrichment on soil physico-chemical property and soil enzyme activities in desert ecosystems, a field experiment by adding N at 0, 1.75, 3.5, 7, or 14 g N x m(-2) a(-1) was conducted in a temperate desert steppe in the southeastern fringe of the Tengger Desert. The results showed that N addition led to accumulations of total N, NO(3-)-N, NH(4+)-N, and available N in the upper soil (0-10 cm) and subsoil (10-20 cm), however, reductions in soil pH were observed, causing soil acidification to some extent. N addition pronouncedly inhibited soil enzyme activities, which were different among N addition levels, soil depths, and years, respectively. Soil enzyme activities were significantly correlated with the soil N level, soil pH, and soil moisture content, respectively.

  19. Thermal properties of ration components as affected by moisture content and water activity during freezing.

    PubMed

    Li, J; Chinachoti, P; Wang, D; Hallberg, L M; Sun, X S

    2008-11-01

    Beef roast with vegetables is an example of a meal, ready-to-eat (MRE) ration entrée. It is a mixture of meat, potato, mushroom, and carrot with a gravy sauce. The thermal properties of each component were characterized in terms of freezing point, latent heat, freezable and unfreezable water contents, and enthalpy during freezing using differential scanning calorimetry. Freezing and thawing curves and the effect of freezing and thawing cycles on thermal properties were also evaluated. The freezing points of beef, potato, mushroom, and sauce were all in the range of -5.1 to -5.6 degrees C, but moisture content, water activity, latent heat, freezable and unfreezable water contents, and enthalpy varied among these components. Freezing temperature greatly affected the unfrozen water fraction. The unfreezable water content (unfrozen water fraction at -50 degrees C) of ration components was in the range of 8.2% to 9.7%. The freezing and thawing curves of vegetables with sauce differed from those of beef but took similar time to freeze or thaw. Freezing and thawing cycles did not greatly affect the thermal properties of each component. Freezing point and latent heat were reduced by decreasing moisture content and water activity of each component. Water activity was proportionally linear to freezing point at a(w) > 0.88, and moisture content was proportionally linear to freezable water content in all ration components. Water was not available for freezing when moisture content was reduced to 28.8% or less. This study indicates that moisture content and water activity are critical factors affecting thermal behavior of ration components during freezing.

  20. Psychometric Properties of the Arabic Version of the Summary of Diabetes Self-Care Activities Instrument.

    PubMed

    Sukkarieh-Haraty, Ola; Howard, Elizabeth

    2016-01-01

    Translation of instruments needs to ensure equivalence between the source and the target language to establish the psychometric properties of the translated version. The purpose of this study was to examine the psychometric properties of the Arabic version of the Summary of Diabetes Self-Care Activities (SDSCA) instrument. The 12-item English version of the SDSCA was translated into Arabic using back translation on a sample of 140 Lebanese participants with Type 2 diabetes. Construct validity was measured using exploratory factor analysis with varimax rotation. Multitrait scaling analysis was used to test for item convergent and discriminant validity based on item-scale correlations. Conceptual and content validity were examined by an expert panel in diabetes. Internal consistency reliability R was assessed using interitem correlations. The average interitem correlation for the four subscales ranged between--.05 for Diet and .66 for Glucose Testing. Factor analysis identified four factors which accounted for 60% of the variance. The preliminary results of Summary of Diabetes Self-Care Activities-Arabic Version (SDSCA-Ar) are comparable to the psychometric properties the original SDSCA. SDSCA-Ar is a valid measure of diabetes self-care in Lebanese patients with diabetes.

  1. Psychometric Properties of the Arabic Version of the Summary of Diabetes Self-Care Activities Instrument.

    PubMed

    Sukkarieh-Haraty, Ola; Howard, Elizabeth

    2016-01-01

    Translation of instruments needs to ensure equivalence between the source and the target language to establish the psychometric properties of the translated version. The purpose of this study was to examine the psychometric properties of the Arabic version of the Summary of Diabetes Self-Care Activities (SDSCA) instrument. The 12-item English version of the SDSCA was translated into Arabic using back translation on a sample of 140 Lebanese participants with Type 2 diabetes. Construct validity was measured using exploratory factor analysis with varimax rotation. Multitrait scaling analysis was used to test for item convergent and discriminant validity based on item-scale correlations. Conceptual and content validity were examined by an expert panel in diabetes. Internal consistency reliability R was assessed using interitem correlations. The average interitem correlation for the four subscales ranged between--.05 for Diet and .66 for Glucose Testing. Factor analysis identified four factors which accounted for 60% of the variance. The preliminary results of Summary of Diabetes Self-Care Activities-Arabic Version (SDSCA-Ar) are comparable to the psychometric properties the original SDSCA. SDSCA-Ar is a valid measure of diabetes self-care in Lebanese patients with diabetes. PMID:27025000

  2. Comparative modeling and molecular dynamics suggest high carboxylase activity of the Cyanobium sp. CACIAM14 RbcL protein.

    PubMed

    Siqueira, Andrei Santos; Lima, Alex Ranieri Jerônimo; Dall'Agnol, Leonardo Teixeira; de Azevedo, Juliana Simão Nina; da Silva Gonçalves Vianez, João Lídio; Gonçalves, Evonnildo Costa

    2016-03-01

    Rubisco catalyzes the first step reaction in the carbon fixation pathway, bonding atmospheric CO2/O2 to ribulose 1,5-bisphosphate; it is therefore considered one of the most important enzymes in the biosphere. Genetic modifications to increase the carboxylase activity of rubisco are a subject of great interest to agronomy and biotechnology, since this could increase the productivity of biomass in plants, algae and cyanobacteria and give better yields in crops and biofuel production. Thus, the aim of this study was to characterize in silico the catalytic domain of the rubisco large subunit (rbcL gene) of Cyanobium sp. CACIAM14, and identify target sites to improve enzyme affinity for ribulose 1,5-bisphosphate. A three-dimensional model was built using MODELLER 9.14, molecular dynamics was used to generate a 100 ns trajectory by AMBER12, and the binding free energy was calculated using MM-PBSA, MM-GBSA and SIE methods with alanine scanning. The model obtained showed characteristics of form-I rubisco, with 15 beta sheets and 19 alpha helices, and maintained the highly conserved catalytic site encompassing residues Lys175, Lys177, Lys201, Asp203, and Glu204. The binding free energy of the enzyme-substrate complexation of Cyanobium sp. CACIAM14 showed values around -10 kcal mol(-1) using the SIE method. The most important residues for the interaction with ribulose 1,5-bisphosphate were Arg295 followed by Lys334. The generated model was successfully validated, remaining stable during the whole simulation, and demonstrated characteristics of enzymes with high carboxylase activity. The binding analysis revealed candidates for directed mutagenesis sites to improve rubisco's affinity.

  3. Modelling Feedback Excitation, Pacemaker Properties and Sensory Switching of Electrically Coupled Brainstem Neurons Controlling Rhythmic Activity

    PubMed Central

    Hull, Michael J.; Soffe, Stephen R.; Willshaw, David J.; Roberts, Alan

    2016-01-01

    What cellular and network properties allow reliable neuronal rhythm generation or firing that can be started and stopped by brief synaptic inputs? We investigate rhythmic activity in an electrically-coupled population of brainstem neurons driving swimming locomotion in young frog tadpoles, and how activity is switched on and off by brief sensory stimulation. We build a computational model of 30 electrically-coupled conditional pacemaker neurons on one side of the tadpole hindbrain and spinal cord. Based on experimental estimates for neuron properties, population sizes, synapse strengths and connections, we show that: long-lasting, mutual, glutamatergic excitation between the neurons allows the network to sustain rhythmic pacemaker firing at swimming frequencies following brief synaptic excitation; activity persists but rhythm breaks down without electrical coupling; NMDA voltage-dependency doubles the range of synaptic feedback strengths generating sustained rhythm. The network can be switched on and off at short latency by brief synaptic excitation and inhibition. We demonstrate that a population of generic Hodgkin-Huxley type neurons coupled by glutamatergic excitatory feedback can generate sustained asynchronous firing switched on and off synaptically. We conclude that networks of neurons with NMDAR mediated feedback excitation can generate self-sustained activity following brief synaptic excitation. The frequency of activity is limited by the kinetics of the neuron membrane channels and can be stopped by brief inhibitory input. Network activity can be rhythmic at lower frequencies if the neurons are electrically coupled. Our key finding is that excitatory synaptic feedback within a population of neurons can produce switchable, stable, sustained firing without synaptic inhibition. PMID:26824331

  4. Modelling Feedback Excitation, Pacemaker Properties and Sensory Switching of Electrically Coupled Brainstem Neurons Controlling Rhythmic Activity.

    PubMed

    Hull, Michael J; Soffe, Stephen R; Willshaw, David J; Roberts, Alan

    2016-01-01

    What cellular and network properties allow reliable neuronal rhythm generation or firing that can be started and stopped by brief synaptic inputs? We investigate rhythmic activity in an electrically-coupled population of brainstem neurons driving swimming locomotion in young frog tadpoles, and how activity is switched on and off by brief sensory stimulation. We build a computational model of 30 electrically-coupled conditional pacemaker neurons on one side of the tadpole hindbrain and spinal cord. Based on experimental estimates for neuron properties, population sizes, synapse strengths and connections, we show that: long-lasting, mutual, glutamatergic excitation between the neurons allows the network to sustain rhythmic pacemaker firing at swimming frequencies following brief synaptic excitation; activity persists but rhythm breaks down without electrical coupling; NMDA voltage-dependency doubles the range of synaptic feedback strengths generating sustained rhythm. The network can be switched on and off at short latency by brief synaptic excitation and inhibition. We demonstrate that a population of generic Hodgkin-Huxley type neurons coupled by glutamatergic excitatory feedback can generate sustained asynchronous firing switched on and off synaptically. We conclude that networks of neurons with NMDAR mediated feedback excitation can generate self-sustained activity following brief synaptic excitation. The frequency of activity is limited by the kinetics of the neuron membrane channels and can be stopped by brief inhibitory input. Network activity can be rhythmic at lower frequencies if the neurons are electrically coupled. Our key finding is that excitatory synaptic feedback within a population of neurons can produce switchable, stable, sustained firing without synaptic inhibition.

  5. Bactericidal Effects against S. aureus and Physicochemical Properties of Plasma Activated Water stored at different temperatures

    PubMed Central

    Shen, Jin; Tian, Ying; Li, Yinglong; Ma, Ruonan; Zhang, Qian; Zhang, Jue; Fang, Jing

    2016-01-01

    Water activated by non-thermal plasma creates an acidified solution containing reactive oxygen and nitrogen species, known as plasma-activated water (PAW). The objective of this study was to investigate the effects of different storage temperatures (25 °C, 4 °C, −20 °C, −80 °C) on bactericidal activities against S. aureus and physicochemical properties of PAW up to 30 days. Interestingly, PAW stored at −80 °C yielded the best antibacterial activity against Staphylococcus aureus, 3~4 log reduction over a 30-day period after PAW generation; meanwhile, PAW stored at 25 °C, 4 °C, and −20 °C, respectively, yielded 0.2~2 log decrease in cell viability after the same exposure and storage time. These results were verified by scanning electron microscope (SEM). The physicochemical properties of PAW stored at different temperatures were evaluated, including pH, oxidation reduction potential (ORP), and hydrogen peroxide, nitrate, nitrite anion and NO radical levels. These findings suggested that bacterial activity of PAW stored at 25 °C, 4 °C, −20 °C decreased over time, and depended on three germicidal factors, specifically ORP, H2O2, and NO3−. Moreover, PAW stored at −80 °C retained bactericidal activity, with NO2− contributing to bactericidal ability in association with H2O2. Our findings provide a basis for PAW storage and practical applications in disinfection and food preservation. PMID:27346695

  6. Bactericidal Effects against S. aureus and Physicochemical Properties of Plasma Activated Water stored at different temperatures

    NASA Astrophysics Data System (ADS)

    Shen, Jin; Tian, Ying; Li, Yinglong; Ma, Ruonan; Zhang, Qian; Zhang, Jue; Fang, Jing

    2016-06-01

    Water activated by non-thermal plasma creates an acidified solution containing reactive oxygen and nitrogen species, known as plasma-activated water (PAW). The objective of this study was to investigate the effects of different storage temperatures (25 °C, 4 °C, ‑20 °C, ‑80 °C) on bactericidal activities against S. aureus and physicochemical properties of PAW up to 30 days. Interestingly, PAW stored at ‑80 °C yielded the best antibacterial activity against Staphylococcus aureus, 3~4 log reduction over a 30-day period after PAW generation; meanwhile, PAW stored at 25 °C, 4 °C, and ‑20 °C, respectively, yielded 0.2~2 log decrease in cell viability after the same exposure and storage time. These results were verified by scanning electron microscope (SEM). The physicochemical properties of PAW stored at different temperatures were evaluated, including pH, oxidation reduction potential (ORP), and hydrogen peroxide, nitrate, nitrite anion and NO radical levels. These findings suggested that bacterial activity of PAW stored at 25 °C, 4 °C, ‑20 °C decreased over time, and depended on three germicidal factors, specifically ORP, H2O2, and NO3‑. Moreover, PAW stored at ‑80 °C retained bactericidal activity, with NO2‑ contributing to bactericidal ability in association with H2O2. Our findings provide a basis for PAW storage and practical applications in disinfection and food preservation.

  7. Biocompatibility and other properties of acrylic bone cements prepared with antiseptic activators.

    PubMed

    de la Torre, B; Fernández, M; Vázquez, B; Collía, F; de Pedro, J A; López-Bravo, A; San Román, J

    2003-08-15

    Acrylic bone cements prepared with activators of reduced toxicity have been formulated with the aim of improving the biocompatibility of the final material. The activators used were N,N-dimethylaminobenzyl alcohol (DMOH) and 4,4'-dimethylamino benzydrol (BZN). The toxicity, cytotoxicity, and antiseptic action of these activators were first studied. DMOH and BZN presented LD50 values 3-4 times higher than DMT, were less cytotoxic against polymorphonuclear leucocytes, and possessed an antimicrobial character, with a high activity against the most representative microorganisms involved in postoperative infections. The properties of the acrylic bone cements formulated with DMOH and BZN were evaluated to determine the influence of these activators on the curing process and the physicochemical characteristics of the cements. A decrease of the peak temperature was observed for the curing with DMOH or BZN with respect to that of one commercially available formulation (CMW 3). However, residual monomer content and mechanical properties in tension and compression were comparable to those of CMW 3. The biocompatibility of acrylic bone cements containing DMOH or BZN was studied and compared with CMW 3. To that end, intramuscular and intraosseous implantation procedures were carried out and the results were obtained from the histological analysis of the surrounding tissues at different periods of time. Implantation of rods of cement into the dorsal muscle of rats showed the presence of a membrane of connective tissue, which increased in collagen fibers with time of implantation, for all formulations. The intraosseous implantation of the cements in the dough state in the femur of rabbits, revealed a higher and early osseous neoformation, with the presence of osteoid material surrounding the rest of the cured material, for the cement prepared with the activator BZN in comparison with that obtained following the implantation of the cement cured with DMOH or DMT (CMW 3).

  8. Activation of spleen cells by ArtinM may account for its immunomodulatory properties.

    PubMed

    Silva, Thiago Aparecido da; Souza, Maria Aparecida de; Cecílio, Nerry Tatiana; Roque-Barreira, Maria Cristina

    2014-09-01

    ArtinM is a D-mannose-binding lectin extracted from Artocarpus heterophyllus that promotes interleukin-12 production by macrophages and dendritic cells. This property is considered responsible for T helper 1 immunity induced in vivo after ArtinM administration. In this study, we investigated the effect of native (jArtinM) and recombinant (rArtinM) forms of lectin on murine spleen cells and isolated T lymphocytes. We found that ArtinM binds to the surface of spleen cells. This interaction, which was blocked by D-mannose, induced cell activation, as manifested by increased mitochondrial activity, interleukin-2 production, and cell proliferation. We verified that a 30-times higher concentration of rArtinM was required to trigger optimal activation of spleen cells compared with that needed with jArtinM, although these proteins have identical sugar recognition properties and use the same signaling molecules to trigger cell activation. Because the distinction between native and recombinant is restricted to their tertiary structure (tetrameric and monomeric, respectively), we postulated that the multi-valence of jArtinM accounts for its superiority in promoting clustering of cell surface glycoreceptors and activation. The jArtinM and rArtinM activation effect exerted on spleen cells was reproduced on purified CD4(+) T cells. Our results suggest that ArtinM interaction with T cells leads to responses that may act in concert with the interleukin-12 produced by antigen-presenting cells to modulate immunity toward the T helper 1 axis. Further studies are necessary to dissect ArtinM/T-cell interactions to more fully understand the immunomodulation induced by carbohydrate recognition. PMID:24842046

  9. Bactericidal Effects against S. aureus and Physicochemical Properties of Plasma Activated Water stored at different temperatures.

    PubMed

    Shen, Jin; Tian, Ying; Li, Yinglong; Ma, Ruonan; Zhang, Qian; Zhang, Jue; Fang, Jing

    2016-06-27

    Water activated by non-thermal plasma creates an acidified solution containing reactive oxygen and nitrogen species, known as plasma-activated water (PAW). The objective of this study was to investigate the effects of different storage temperatures (25 °C, 4 °C, -20 °C, -80 °C) on bactericidal activities against S. aureus and physicochemical properties of PAW up to 30 days. Interestingly, PAW stored at -80 °C yielded the best antibacterial activity against Staphylococcus aureus, 3~4 log reduction over a 30-day period after PAW generation; meanwhile, PAW stored at 25 °C, 4 °C, and -20 °C, respectively, yielded 0.2~2 log decrease in cell viability after the same exposure and storage time. These results were verified by scanning electron microscope (SEM). The physicochemical properties of PAW stored at different temperatures were evaluated, including pH, oxidation reduction potential (ORP), and hydrogen peroxide, nitrate, nitrite anion and NO radical levels. These findings suggested that bacterial activity of PAW stored at 25 °C, 4 °C, -20 °C decreased over time, and depended on three germicidal factors, specifically ORP, H2O2, and NO3(-). Moreover, PAW stored at -80 °C retained bactericidal activity, with NO2(-) contributing to bactericidal ability in association with H2O2. Our findings provide a basis for PAW storage and practical applications in disinfection and food preservation.

  10. Plutonium behavior after pulmonary administration according to solubility properties, and consequences on alveolar macrophage activation.

    PubMed

    Van der Meeren, Anne; Gremy, Olivier; Renault, Daniel; Miroux, Amandine; Bruel, Sylvie; Griffiths, Nina; Tourdes, Françoise

    2012-01-01

    The physico-chemical form in which plutonium enters the body influences the lung distribution and the transfer rate from lungs to blood. In the present study, we evaluated the early lung damage and macrophage activation after pulmonary contamination of plutonium of various preparation modes which produce different solubility and distribution patterns. Whatever the solubility properties of the contaminant, macrophages represent a major retention compartment in lungs, with 42 to 67% of the activity from broncho-alveolar lavages being associated with macrophages 14 days post-contamination. Lung changes were observed 2 and 6 weeks post-contamination, showing inflammatory lesions and accumulation of activated macrophages (CD68 positive) in plutonium-contaminated rats, although no increased proliferation of pneumocytes II (TTF-1 positive cells) was found. In addition, acid phosphatase activity in macrophages from contaminated rats was enhanced 2 weeks post-contamination as compared to sham groups, as well as inflammatory mediator levels (TNF-α, MCP-1, MIP-2 and CINC-1) in macrophage culture supernatants. Correlating with the decrease in activity remaining in macrophages after plutonium contamination, inflammatory mediator production returned to basal levels 6 weeks post-exposure. The production of chemokines by macrophages was evaluated after contamination with Pu of increasing solubility. No correlation was found between the solubility properties of Pu and the activation level of macrophages. In summary, our data indicate that, despite the higher solubility of plutonium citrate or nitrate as compared to preformed colloids or oxides, macrophages remain the main lung target after plutonium contamination and may participate in the early pulmonary damage.

  11. Activation of spleen cells by ArtinM may account for its immunomodulatory properties.

    PubMed

    Silva, Thiago Aparecido da; Souza, Maria Aparecida de; Cecílio, Nerry Tatiana; Roque-Barreira, Maria Cristina

    2014-09-01

    ArtinM is a D-mannose-binding lectin extracted from Artocarpus heterophyllus that promotes interleukin-12 production by macrophages and dendritic cells. This property is considered responsible for T helper 1 immunity induced in vivo after ArtinM administration. In this study, we investigated the effect of native (jArtinM) and recombinant (rArtinM) forms of lectin on murine spleen cells and isolated T lymphocytes. We found that ArtinM binds to the surface of spleen cells. This interaction, which was blocked by D-mannose, induced cell activation, as manifested by increased mitochondrial activity, interleukin-2 production, and cell proliferation. We verified that a 30-times higher concentration of rArtinM was required to trigger optimal activation of spleen cells compared with that needed with jArtinM, although these proteins have identical sugar recognition properties and use the same signaling molecules to trigger cell activation. Because the distinction between native and recombinant is restricted to their tertiary structure (tetrameric and monomeric, respectively), we postulated that the multi-valence of jArtinM accounts for its superiority in promoting clustering of cell surface glycoreceptors and activation. The jArtinM and rArtinM activation effect exerted on spleen cells was reproduced on purified CD4(+) T cells. Our results suggest that ArtinM interaction with T cells leads to responses that may act in concert with the interleukin-12 produced by antigen-presenting cells to modulate immunity toward the T helper 1 axis. Further studies are necessary to dissect ArtinM/T-cell interactions to more fully understand the immunomodulation induced by carbohydrate recognition.

  12. Bactericidal Effects against S. aureus and Physicochemical Properties of Plasma Activated Water stored at different temperatures.

    PubMed

    Shen, Jin; Tian, Ying; Li, Yinglong; Ma, Ruonan; Zhang, Qian; Zhang, Jue; Fang, Jing

    2016-01-01

    Water activated by non-thermal plasma creates an acidified solution containing reactive oxygen and nitrogen species, known as plasma-activated water (PAW). The objective of this study was to investigate the effects of different storage temperatures (25 °C, 4 °C, -20 °C, -80 °C) on bactericidal activities against S. aureus and physicochemical properties of PAW up to 30 days. Interestingly, PAW stored at -80 °C yielded the best antibacterial activity against Staphylococcus aureus, 3~4 log reduction over a 30-day period after PAW generation; meanwhile, PAW stored at 25 °C, 4 °C, and -20 °C, respectively, yielded 0.2~2 log decrease in cell viability after the same exposure and storage time. These results were verified by scanning electron microscope (SEM). The physicochemical properties of PAW stored at different temperatures were evaluated, including pH, oxidation reduction potential (ORP), and hydrogen peroxide, nitrate, nitrite anion and NO radical levels. These findings suggested that bacterial activity of PAW stored at 25 °C, 4 °C, -20 °C decreased over time, and depended on three germicidal factors, specifically ORP, H2O2, and NO3(-). Moreover, PAW stored at -80 °C retained bactericidal activity, with NO2(-) contributing to bactericidal ability in association with H2O2. Our findings provide a basis for PAW storage and practical applications in disinfection and food preservation. PMID:27346695

  13. Thalamic Kv7 channels: pharmacological properties and activity control during noxious signal processing

    PubMed Central

    Cerina, Manuela; Szkudlarek, Hanna J; Coulon, Philippe; Meuth, Patrick; Kanyshkova, Tatyana; Nguyen, Xuan Vinh; Göbel, Kerstin; Seidenbecher, Thomas; Meuth, Sven G; Pape, Hans-Christian; Budde, Thomas

    2015-01-01

    Background and Purpose The existence of functional Kv7 channels in thalamocortical (TC) relay neurons and the effects of the K+-current termed M-current (IM) on thalamic signal processing have long been debated. Immunocytochemical evidence suggests their presence in this brain region. Therefore, we aimed to verify their existence, pharmacological properties and function in regulating activity in neurons of the ventrobasal thalamus (VB). Experimental Approach Characterization of Kv7 channels was performed by combining in vitro, in vivo and in silico techniques with a pharmacological approach. Retigabine (30 μM) and XE991 (20 μM), a specific Kv7 channel enhancer and blocker, respectively, were applied in acute brain slices during electrophysiological recordings. The effects of intrathalamic injection of retigabine (3 mM, 300 nL) and/or XE991 (2 mM, 300 nL) were investigated in freely moving animals during hot-plate tests by recording behaviour and neuronal activity. Key Results Kv7.2 and Kv7.3 subunits were found to be abundantly expressed in TC neurons of mouse VB. A slow K+-current with properties of IM was activated by retigabine and inhibited by XE991. Kv7 channel activation evoked membrane hyperpolarization, a reduction in tonic action potential firing, and increased burst firing in vitro and in computational models. Single-unit recordings and pharmacological intervention demonstrated a specific burst-firing increase upon IM activation in vivo. A Kv7 channel-mediated increase in pain threshold was associated with fewer VB units responding to noxious stimuli, and increased burst firing in responsive neurons. Conclusions and Implications Kv7 channel enhancement alters somatosensory activity and may reflect an anti-nociceptive mechanism during acute pain processing. PMID:25684311

  14. M-wave properties during progressive motor unit activation by transcutaneous stimulation.

    PubMed

    Farina, Dario; Blanchietti, Andrea; Pozzo, Marco; Merletti, Roberto

    2004-08-01

    The aim of this study was to interpret changes in experimentally recorded M waves with progressive motor unit (MU) activation based on simulation of the surface electromyogram. Activation order during transcutaneous electrical stimulation was analyzed by investigating M-wave average rectified value, spectral properties, and conduction velocity (CV) during electrically elicited contractions. M-waves were detected from the biceps brachii muscle of 10 healthy male subjects by a linear adhesive array of eight electrodes. Electrical stimulation was delivered to the motor point at either constant current intensity (40, 60, 80, and 100% of the supramaximal stimulation current) or with linearly increasing current. A model of surface electromyogram generation that varied activation order based on MU size and location was used to interpret the experimental results. From the experimental and model analysis, it was found that 1) MUs tended to be activated from low to high CV and from the superficial to the deep muscle layers with increasing transcutaneous electrical stimulation of the biceps brachii muscle, and 2) characteristic spectral frequencies of the M-wave were affected by many factors other than average CV (such as the activation order by MU location or the spread of the MU innervation zones and CVs), thus decreasing with a concomitant increase in CV during progressive MU activation.

  15. Synthesis, biophysical properties and biological activity of second generation antisense oligonucleotides containing chiral phosphorothioate linkages

    PubMed Central

    Wan, W. Brad; Migawa, Michael T.; Vasquez, Guillermo; Murray, Heather M.; Nichols, Josh G.; Gaus, Hans; Berdeja, Andres; Lee, Sam; Hart, Christopher E.; Lima, Walt F.; Swayze, Eric E.; Seth, Punit P.

    2014-01-01

    Bicyclic oxazaphospholidine monomers were used to prepare a series of phosphorothioate (PS)-modified gapmer antisense oligonucleotides (ASOs) with control of the chirality of each of the PS linkages within the 10-base gap. The stereoselectivity was determined to be 98% for each coupling. The objective of this work was to study how PS chirality influences biophysical and biological properties of the ASO including binding affinity (Tm), nuclease stability, activity in vitro and in vivo, RNase H activation and cleavage patterns (both human and E. coli) in a gapmer context. Compounds that had nine or more Sp-linkages in the gap were found to be poorly active in vitro, while compounds with uniform Rp-gaps exhibited activity very similar to that of the stereo-random parent ASOs. Conversely, when tested in vivo, the full Rp-gap compound was found to be quickly metabolized resulting in low activity. A total of 31 ASOs were prepared with control of the PS chirally of each linkage within the gap in an attempt to identify favorable Rp/Sp positions. We conclude that a mix of Rp and Sp is required to achieve a balance between good activity and nuclease stability. PMID:25398895

  16. Properties of the long-term optical activity of the prototype polar AM Herculis

    NASA Astrophysics Data System (ADS)

    Šimon, Vojtěch

    2016-08-01

    AM Her displays strong long-term activity with the high and low states. This investigation uses AAVSO optical data for a time-series analysis of the long-term variations. Rapid changes of brightness (e.g. the orbital modulation) were smoothed out to emphasise the activity on super-orbital time-scale. I show that the character of this activity changed considerably on time-scales of years, which is reflected in a large evolution of the complicated histogram of the optical brightness. The high states are not the well-defined, narrow levels of brightness. I also show that AM Her displays transitions between the high and low states with the intermittently existing cycles. The longest uninterrupted series of transitions from the high to low state consists of seven episodes (about six years). The existence of this series can be controlled by the lifetime of the active regions on the donor, which modulates the mass transfer rate. I show that the episodes of the high and low states accumulate in clusters, which produces an additional cycle after smoothing by the moving averages. The cycles of activity of the donor can explain this modulation. A single isolated short episode of the low state does not imply a break of this cycle. I also argue that the specific properties of star spots and their migration caused by the differential rotation of the donor would be needed to explain the complex activity of AM Her.

  17. Adsorption properties of CFC and CFC replacements on activated carbon containing introduced ionic fluoride and chloride

    SciTech Connect

    Tanada, Seiki; Kawasaki, Naohito; Nakamura, Takeo; Abe, Ikuo

    1996-10-15

    Plasma technology has been available for the chlorofluorocarbon (CFC) decomposition or etching of silicone. The adsorption properties of CFC (CFC113) and CFC replacements (HCFC141b, HCFC225cb, and 5FP) on several kinds of plasma-treated activated carbons (P-ACs) prepared under different treatment gases were investigated using the adsorption isotherms, the limiting pore volume and the affinity coefficient and energy of adsorption calculated by the Dubinin-Radushkevich plot, and the quality and kinds of introduced fluoride and chloride. The dissolved fluoride and chloride atoms were introduced to the surface of activated carbon by CFC113, HCFC141b, and HCFC225cb, while the dissolved fluoride atoms were those from 5FP and tetrafluoromethane. The adsorbed amount of CFC and CFC replacements, except for 5FP, on P-ACs was larger than that on U-AC. The specific adsorption site on plasma-treated activated carbon of the CFC and CFC replacements was the fluoride atoms which were introduced by plasma treatment. It is concluded that the plasma-treated activated carbon was suitable for the recovery of CFC and CFC replacements, because the adsorbed amount of CFC and CFC replacements was larger than that on untreated activated carbon, and the adsorbed CFC and CFC replacements on activated carbon were decomposed by the plasma treatment.

  18. Magnetite impregnation effects on the sorbent properties of activated carbons and biochars.

    PubMed

    Han, Zhantao; Sani, Badruddeen; Mrozik, Wojciech; Obst, Martin; Beckingham, Barbara; Karapanagioti, Hrissi K; Werner, David

    2015-03-01

    This paper discusses the sorbent properties of magnetic activated carbons and biochars produced by wet impregnation with iron oxides. The sorbents had magnetic susceptibilities consistent with theoretical predictions for carbon-magnetite composites. The high BET surface areas of the activated carbons were preserved in the synthesis, and enhanced for one low surface area biochar by dissolving carbonates. Magnetization decreased the point of zero charge. Organic compound sorption correlated strongly with BET surface areas for the pristine and magnetized materials, while metal cation sorption did not show such a correlation. Strong sorption of the hydrophobic organic contaminant phenanthrene to the activated carbon or biochar surfaces was maintained following magnetite impregnation, while phenol sorption was diminished, probably due to enhanced carbon oxidation. Copper, zinc and lead sorption to the activated carbons and biochars was unchanged or slightly enhanced by the magnetization, and iron oxides also contributed to the composite metal sorption capacity. While a magnetic biochar with 219 ± 3.7 m(2)/g surface area nearly reached the very strong organic pollutant binding capacity of the two magnetic activated carbons, a magnetic biochar with 68 ± 2.8 m(2)/g surface area was the best metal sorbent. Magnetic biochars thus hold promise as more sustainable alternatives to coal-derived magnetic activated carbons.

  19. Theoretical study of nitrodibenzofurans: A possible relationship between molecular properties and mutagenic activity.

    PubMed

    Stanković, B; Ostojić, B D; Popović, A; Gruden, M А; Đorđević, D S

    2016-11-15

    In this study we present a theoretical investigation of the molecular properties of nitrodibenzofurans (NDFs) and dinitrodibenzofurans (DNDFs) and their relation to mutagenic activity. Equilibrium geometries, relative energies, vertical ionization potentials (IP), vertical electron activities (EA), electronic dipole polarizabilities, and dipole moments of all NDFs and three DNDFs calculated by Density Functional Theory (DFT) methods are reported. The Ziegler/Rauk Energy Decomposition Analysis (EDA) is employed for a direct estimate of the variations of the orbital interaction and steric repulsion terms corresponding to the nitro group and the oxygen of the central ring of NDFs. The results indicate differences among NDF isomers for the cleavage of the related bonds and steric effects in the active site. The results show a good linear relationship between polarizability (<α>), anisotropy of polarizability (Δα), the summation of IR intensities (ΣIIR) and the summation of Raman activities (ΣARaman) over all 3N-6 vibrational modes and experimental mutagenic activities of NDF isomers in Salmonella typhimurium TA98 strain. The polarizability changes with respect to the νsNO+CN vibrational mode are in correlation with the mutagenic activities of NDFs and suggest that intermolecular interactions are favoured along this coordinate. PMID:27475460

  20. Antibacterial properties and major bioactive components of cinnamon stick (Cinnamomum burmannii): activity against foodborne pathogenic bacteria.

    PubMed

    Shan, Bin; Cai, Yi-Zhong; Brooks, John D; Corke, Harold

    2007-07-11

    Cinnamomum burmannii Blume (cinnamon stick) from Indonesia is a little-investigated spice. In this study, the antibacterial activity, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of cinnamon stick extract were evaluated against five common foodborne pathogenic bacteria (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Salmonella anatum). Cinnamon stick extract exhibited significant antibacterial properties. Major compounds in cinnamon stick were tentatively identified by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography (LC-MS) as a predominant volatile oil component ((E)-cinnamaldehyde) and several polyphenols (mainly proanthocyanidins and (epi)catechins). Both (E)-cinnamaldehyde and proanthocyanidins significantly contributed to the antibacterial properties. Additionally, scanning electron microscopy was used to observe morphological changes of bacteria treated with the crude extract of cinnamon stick and its major components. This study suggests that cinnamon stick and its bioactive components have potential for application as natural food preservatives.

  1. Effect of Worm Predation on Changes in Waste Activated Sludge Properties.

    PubMed

    Zhu, Xuefeng; Yuan, Wenyi; Wang, Zhiwei; Zhou, Mingyuan; Guan, Jie

    2016-05-01

    This study explored the effects of worm predation on changes in waste activated sludge properties. Results showed that the rate by which worm predation reduced mixed liquor volatile suspended solids (MLVSS) was approximately 23.7% ± 3.1%. Particle size distribution and extracellular polymeric substance (EPS) analyses indicated that the reduction of fine particles and EPS content in sludge predated by worms mainly increased dewaterability and reduced the ratio of MLVSS/mixed liquor suspended solids. Moreover, both mean particle size and protein/carbohydrate ratio increased. The results of three-dimensional excitation-emission matrix and gel filtration chromatogram analyses demonstrated the varied properties of soluble microbial products and EPS were attributed to the worms' selective predation of low molecular-weight organic matter, which facilitated the hydrolysis of macromolecular organic matter. PMID:27131302

  2. Surface modification and electrochemical properties of activated carbons for supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Yang, Dan; Qiu, Wenmei; Xu, Jingcai; Han, Yanbing; Jin, Hongxiao; Jin, Dingfeng; Peng, Xiaoling; Hong, Bo; Li, Ji; Ge, Hongliang; Wang, Xinqing

    2015-12-01

    Modifications with different acids (HNO3, H2SO4, HCl and HF, respectively) were introduced to treat the activated carbons (ACs) surface. The microstructures and surface chemical properties were discussed by X-ray diffraction (XRD), thermogravimetric analysis (TGA), ASAP, Raman spectra and Fourier transform infrared (FTIR) spectra. The ACs electrode-based supercapacitors were assembled with 6 mol ṡ L-1 KOH electrolyte. The electrochemical properties were studied by galvanostatic charge-discharge and cyclic voltammetry. The results indicated that although the BET surface area of modified ACs decreased, the functional groups were introduced and the ash contents were reduced on the surface of ACs, receiving larger specific capacitance to initial AC. The specific capacitance of ACs modified with HCl, H2SO4, HF and HNO3 increased by 31.4%, 23%, 21% and 11.6%, respectively.

  3. Enhancement of the photocatalytic activity and electrochemical property of graphene-SrWO4 nanocomposite

    NASA Astrophysics Data System (ADS)

    Liu, Xiaoyan; Nie, Yu; Yang, Hongxun; Sun, Shengnan; Chen, Yingying; Yang, Tongyi; Lin, Shengling

    2016-05-01

    SrWO4 is a promising candidate as not only photocatalyst for the removal of organic pollutants from water, but also electrode material for energy storage devices. However, the drawbacks of its poor adsorptive performance, low electrical conductivity, and high recombination rate of photogenerated electron-hole pair impede its practical applications. In this work, we have developed a new graphene/SrWO4 nanocomposite synthesized via a facile chemical precipitation method. Characterizations show that SrWO4 nanoparticles with 80 nm or so deposited on the surface of graphene nanosheets. Graphene nanosheets in the graphene-SrWO4 hybrid could increase adsorptive property, improve the electrical conductivity of hybrid, and reduce the recombination of electron-hole pairs. As a kind of photocatalyst or electrode material for supercapacitor, the binary graphene-SrWO4 hybrid presents enhanced photocatalytic activity and electrochemical property compared to pure SrWO4.

  4. Antioxidative Properties and Effect of Quercetin and Its Glycosylated Form (Rutin) on Acetylcholinesterase and Butyrylcholinesterase Activities.

    PubMed

    Ademosun, Ayokunle O; Oboh, Ganiyu; Bello, Fatai; Ayeni, Peluola O

    2016-10-01

    This study sought to investigate the anticholinesterase and antioxidative properties of quercetin and its glycosylated conjugate, rutin. The in vitro inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities, inhibition of Fe(2+)-induced lipid peroxidation in rat's brain homogenates, radicals scavenging, and Fe(2+)-chelating abilities of the flavonoids were investigated in vitro with concentrations of the samples ranging from 0.06 to 0.6 mM. Quercetin had significantly higher AChE and BChE inhibitory abilities than rutin. Quercetin also had stronger inhibition of Fe(2+)-induced lipid peroxidation in rat's brain homogenates. Similarly, quercetin had higher radical scavenging abilities than rutin. Quercetin also had stronger Fe(2+)-chelating ability than rutin. The inhibition of cholinesterases and antioxidative properties are possible mechanisms by which the flavonoids can be used in the management of oxidative stress-induced neurodegeneration.

  5. Evolution of galaxy properties across the peak of cosmic activity in cosmological hydrodynamics simulations

    NASA Astrophysics Data System (ADS)

    Devriendt, Julien

    2015-08-01

    In this talk I will review how numerical hydrodynamics simulations predict galaxies evolve in the redshift range 1properties (mass, size, morphology, star formation history).The discussion will be underpinned by recent efforts to measure the degree of alignment between galaxy spins and the large scale cosmic web filaments in which they are embedded. Relative contributions to property evolution will be split between major and minor, gas rich and gas poor mergers as well as smooth accretion, and quantitatively assessed. Finally, switching from nurture to nature, I will also discuss the role played by various feedback processes, whether of stellar origin or driven by active nuclei, in driving such changes or freezing them in.

  6. Activity and kinetic properties of phosphotransacetylase from intestinal sulfate-reducing bacteria.

    PubMed

    Kushkevych, Ivan V

    2015-01-01

    Phosphotransacetylase activity and the kinetic properties of the enzyme from intestinal sulfate-reducing bacteria Desulfovibrio piger and Desulfomicrobium sp. has never been well-characterized and has not been studied yet. In this paper, the specific activity of phosphotransacetylase and the kinetic properties of the enzyme in cell-free extracts of both D. piger Vib-7 and Desulfomicrobium sp. Rod-9 intestinal bacterial strains were presented at the first time. The microbiological, biochemical, biophysical and statistical methods in this work were used. The optimal temperature and pH for enzyme reaction was determined. Analysis of the kinetic properties of the studied enzyme was carried out. Initial (instantaneous) reaction velocity (V0), maximum amount of the product of reaction (Pmax), the reaction time (half saturation period, τ) and maximum velocity of the phosphotransacetylase reaction (Vmax) were defined. Michaelis constants (Km) of the enzyme reaction (3.36 ± 0.35 mM for D. piger Vib-7, 5.97 ± 0.62 mM for Desulfomicrobium sp. Rod-9) were calculated. The studies of the phosphotransacetylase in the process of dissimilatory sulfate reduction and kinetic properties of this enzyme in intestinal sulfate-reducing bacteria, their production of acetate in detail can be perspective for clarification of their etiological role in the development of the humans and animals bowel diseases. These studies might help in predicting the development of diseases of the gastrointestinal tract, by providing further details on the etiology of bowel diseases which are very important for the clinical diagnosis of these disease types.

  7. Effect of ultrasonic treatment on the physicochemical properties and antioxidant activities of polysaccharide from Cyclocarya paliurus.

    PubMed

    Tang, Wei; Lin, Lihua; Xie, Jianhua; Wang, Zhijun; Wang, Hui; Dong, Yujia; Shen, Mingyue; Xie, Mingyong

    2016-10-20

    The effects of ultrasonic treatment on the physicochemical properties and antioxidant activities of the polysaccharide from Cyclocarya paliurus leaves were investigated. The physicochemical properties were detected by high-performance gel permeation chromatography (HPGPC), high-performance anion exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD) and fourier transform infrared spectrometer (FT-IR) as well. The antioxidant activities were evaluated by the assay of DPPH, hydroxyl free radical, β-carotene-linoleic acid, respectfully. Results showed that no considerable change was observed on the structure between the polysaccharide of Cyclocarya paliurus (CP) and the ultrasonic polysaccharide of Cyclocarya paliurus (UCP) by FT-IR, and no apparent differences were found on the content of sugar, uronic acid and protein after the ultrasonic treatment, but difference appeared in the ratio of monosaccharide composition of CP (1.0:4.6:3.5:4.5) and UCP (1.0:5.9:3.9:4.4), and the antioxidant activities of CP were promoted after ultrasonic treatment. PMID:27474571

  8. Soil Properties, Nutrient Dynamics, and Soil Enzyme Activities Associated with Garlic Stalk Decomposition under Various Conditions

    PubMed Central

    Han, Xu; Cheng, Zhihui; Meng, Huanwen

    2012-01-01

    The garlic stalk is a byproduct of garlic production and normally abandoned or burned, both of which cause environmental pollution. It is therefore appropriate to determine the conditions of efficient decomposition, and equally appropriate to determine the impact of this decomposition on soil properties. In this study, the soil properties, enzyme activities and nutrient dynamics associated with the decomposition of garlic stalk at different temperatures, concentrations and durations were investigated. Stalk decomposition significantly increased the values of soil pH and electrical conductivity. In addition, total nitrogen and organic carbon concentration were significantly increased by decomposing stalks at 40°C, with a 5∶100 ratio and for 10 or 60 days. The highest activities of sucrase, urease and alkaline phosphatase in soil were detected when stalk decomposition was performed at the lowest temperature (10°C), highest concentration (5∶100), and shortest duration (10 or 20 days). The evidence presented here suggests that garlic stalk decomposition improves the quality of soil by altering the value of soil pH and electrical conductivity and by changing nutrient dynamics and soil enzyme activity, compared to the soil decomposition without garlic stalks. PMID:23226411

  9. Antibiofilm properties of interfacially active lipase immobilized porous polycaprolactam prepared by LB technique.

    PubMed

    Prabhawathi, Veluchamy; Boobalan, Thulasinathan; Sivakumar, Ponnurengam Malliappan; Doble, Mukesh

    2014-01-01

    Porous biomaterial is the preferred implant due to the interconnectivity of the pores. Chances of infection due to biofilm are also high in these biomaterials because of the presence of pores. Although biofilm in implants contributes to 80% of human infections, there are no commercially available natural therapeutics against it. In the current study, glutaraldehyde cross linked lipase was transferred onto a activated porous polycaprolactam surface using Langmuir-Blodgett deposition technique, and its thermostability, slimicidal, antibacterial, biocompatibility and surface properties were studied. There was a 20% increase in the activity of the covalently crosslinked lipase when compared to its free form. This immobilized surface was thermostable and retained activity and stability until 100°C. There was a 2 and 7 times reduction in carbohydrate and 9 and 5 times reduction in biofilm protein of Staphylococcus aureus and Escherichia coli respectively on lipase immobilized polycaprolactam (LIP) when compared to uncoated polycaprolactam (UP). The number of live bacterial colonies on LIP was four times less than on UP. Lipase acted on the cell wall of the bacteria leading to its death, which was confirmed from AFM, fluorescence microscopic images and amount of lactate dehydrogenase released. LIP allowed proliferation of more than 90% of 3T3 cells indicating that it was biocompatible. The fact that LIP exhibits antimicrobial property at the air-water interface to hydrophobic as well as hydrophilic bacteria along with lack of cytotoxicity makes it an ideal biomaterial for biofilm prevention in implants. PMID:24798482

  10. Preparation and properties of alpha-galactosidase chemically attached to activated chitin.

    PubMed

    Onal, Seçil; Telefoncu, Azmi

    2003-08-01

    alpha-Galactosidase (alpha-D-galactoside galactohydrolase, EC 3.2.1.22) from watermelon was covalently immobilized on chitin. The immobilized alpha-galactosidase exhibited an activity of 0.61 U per g of carrier and an activity yield of 67%. The properties of free and immobilized alpha-galactosidase were also searched and compared. The results showed that, optimum conditions for activity were not affected by immobilization. The optimum pH and temperature for free and immobilized enzyme found as pH 6.0 and 65 degress C, respectively. Compared with the free enzyme, the temperature and pH stabilities of the immobilized enzyme were similar. Both the enzymes were stable between pH 2-10 and below 50 degrees C. The Km values for free and immobilized enzyme were determined using p-nitrophenyl-alpha-D-galactopyranoside (PNPG) and raffinose as substrates. Operational stability of the immobilized enzyme was investigated by using both substrates. The operational half-life (t 1/2) was calculated as 34 h for PNPG and 28 h for raffinose. The immobilized alpha-galactosidase was also utilized in the hydrolysis of raffinose. The immobilization procedure on chitin was cheap and also easy to carry out, and the immobilized enzyme had good properties that the potential for practical application is considerable.

  11. Antibiofilm Properties of Interfacially Active Lipase Immobilized Porous Polycaprolactam Prepared by LB Technique

    PubMed Central

    Prabhawathi, Veluchamy; Boobalan, Thulasinathan; Sivakumar, Ponnurengam Malliappan; Doble, Mukesh

    2014-01-01

    Porous biomaterial is the preferred implant due to the interconnectivity of the pores. Chances of infection due to biofilm are also high in these biomaterials because of the presence of pores. Although biofilm in implants contributes to 80% of human infections [1], there are no commercially available natural therapeutics against it. In the current study, glutaraldehyde cross linked lipase was transferred onto a activated porous polycaprolactam surface using Langmuir-Blodgett deposition technique, and its thermostability, slimicidal, antibacterial, biocompatibility and surface properties were studied. There was a 20% increase in the activity of the covalently crosslinked lipase when compared to its free form. This immobilized surface was thermostable and retained activity and stability until 100°C. There was a 2 and 7 times reduction in carbohydrate and 9 and 5 times reduction in biofilm protein of Staphylococcus aureus and Escherichia coli respectively on lipase immobilized polycaprolactam (LIP) when compared to uncoated polycaprolactam (UP). The number of live bacterial colonies on LIP was four times less than on UP. Lipase acted on the cell wall of the bacteria leading to its death, which was confirmed from AFM, fluorescence microscopic images and amount of lactate dehydrogenase released. LIP allowed proliferation of more than 90% of 3T3 cells indicating that it was biocompatible. The fact that LIP exhibits antimicrobial property at the air-water interface to hydrophobic as well as hydrophilic bacteria along with lack of cytotoxicity makes it an ideal biomaterial for biofilm prevention in implants. PMID:24798482

  12. Fructose 1,6-diphosphate-activated L-lactate dehydrogenase from Streptococcus lactis: kinetic properties and factors affecting activation.

    PubMed Central

    Crow, V L; Pritchard, G G

    1977-01-01

    The L-(+)-lactate dehydrogenase (L-lactate:NAD+ oxidoreductase, EC 1.1.1.27) of Streptococcus lactis C10, like that of other streptococci, was activated by fructose 1,6-diphosphate (FDP). The enzyme showed some activity in the absence of FDP, with a pH optimum of 8.2; FDP decreased the Km for both pyruvate and reduced nicotinamide adenine dinucleotide (NADH) and shifted the pH optimum to 6.9. Enzyme activity showed a hyperbolic response to both NADH and pyruvate in all the buffers tried except phosphate buffer, in which the response to increasing NADH was sigmoidal. The FDP concentration required for half-maximal velocity (FDP0.5V) was markedly influenced by the nature of the assay buffer used. Thus the FDP0.5V was 0.002 mM in 90 mM triethanolamine buffer, 0.2 mM in 90 mM tris(hydroxymethyl)aminomethanemaleate buffer, and 4.4 mM in 90 mM phosphate buffer. Phosphate inhibition of FDP binding is not a general property of streptococcal lactate dehydrogenase, since the FDP0.5V value for S. faecalis 8043 lactate dehydrogenase was not increased by phosphate. The S. faecalis and S. lactis lactate dehydrogenases also differed in that Mn2+ enhanced FDP binding in S. faecalis but had no effect on the S. lactis dehydrogenase. The FDP concentration (12 to 15 mM) found in S. lactis cells during logarithmic growth on a high-carbohydrate (3% lactose) medium would be adequate to give almost complete activation of the lactate dehydrogenase even if the high FDP0.5V value found in 90 mM phosphate were similar to the FDP requirement in vivo. PMID:17595

  13. Neuroprotective and cognition-enhancing properties of MK-801 flexible analogs. Structure-activity relationships.

    PubMed

    Bachurin, S; Tkachenko, S; Baskin, I; Lermontova, N; Mukhina, T; Petrova, L; Ustinov, A; Proshin, A; Grigoriev, V; Lukoyanov, N; Palyulin, V; Zefirov, N

    2001-06-01

    Neuroprotective and biobehavioral properties of a series of novel open chain MK-801 analogs, as well as their structure-activity relationships have been investigated. Three groups of compounds were synthesized: monobenzylamino, benzhydrylamino, and dibenzylamino (DBA) analogs of MK-801. It was revealed that DBA analogs exhibit pronounced glutamate-induced calcium uptake blocking properties and anti-NMDA activity. The hit compound of DBA series, NT-1505, was investigated for its ability to improve cognition functions in animal model of Alzheimer's disease type dementia, simulated by treating animals with cholinotoxin AF64A. The results from an active avoidance test and a Morris water maze test showed that experimental animals, treated additionally with NT-1505, exhibited much better learning ability and memory than the control group (AF64A treated) and close to that of the vehicle group of animals (treated with physiological solution). Study of NT-1505 influence on locomotor activity revealed that it is characterized by a spectrum of behavioral activity radically different from that of MK-801, and in contrast to the latter one does not produce any psychotomimetic side effects in the therapeutically significant dose interval. The computed docking of MK-801 and its flexible analogs on the NMDA receptor elucidated the crucial role of the hydrogen bond formed between these compounds and the asparagine residue for magnesium binding in the NMDA receptor. It was suggested that strong hydrophobic interaction between MK-801 and the hydrophobic pocket in the NMDA receptor-channel complex determines much higher irreversibility of this adduct compared to the intermediates formed between this site and Mg ions or flexible DBA derivatives, which might explain the absence of PCP-like side effects of the latter compounds.

  14. Biophysical properties of Saccharomyces cerevisiae and their relationship with HOG pathway activation

    PubMed Central

    Adrover, Miquel Àngel; Eriksson, Emma; Pelet, Serge; Petelenz-Kurdziel, Elzbieta; Klein, Dagmara; Posas, Francesc; Goksör, Mattias; Peter, Mathias; Hohmann, Stefan

    2010-01-01

    Parameterized models of biophysical and mechanical cell properties are important for predictive mathematical modeling of cellular processes. The concepts of turgor, cell wall elasticity, osmotically active volume, and intracellular osmolarity have been investigated for decades, but a consistent rigorous parameterization of these concepts is lacking. Here, we subjected several data sets of minimum volume measurements in yeast obtained after hyper-osmotic shock to a thermodynamic modeling framework. We estimated parameters for several relevant biophysical cell properties and tested alternative hypotheses about these concepts using a model discrimination approach. In accordance with previous reports, we estimated an average initial turgor of 0.6 ± 0.2 MPa and found that turgor becomes negligible at a relative volume of 93.3 ± 6.3% corresponding to an osmotic shock of 0.4 ± 0.2 Osm/l. At high stress levels (4 Osm/l), plasmolysis may occur. We found that the volumetric elastic modulus, a measure of cell wall elasticity, is 14.3 ± 10.4 MPa. Our model discrimination analysis suggests that other thermodynamic quantities affecting the intracellular water potential, for example the matrix potential, can be neglected under physiological conditions. The parameterized turgor models showed that activation of the osmosensing high osmolarity glycerol (HOG) signaling pathway correlates with turgor loss in a 1:1 relationship. This finding suggests that mechanical properties of the membrane trigger HOG pathway activation, which can be represented and quantitatively modeled by turgor. Electronic supplementary material The online version of this article (doi:10.1007/s00249-010-0612-0) contains supplementary material, which is available to authorized users. PMID:20563574

  15. TRPV4 channel activation improves the tensile properties of self-assembled articular cartilage constructs

    PubMed Central

    Eleswarapu, Sriram V.; Athanasiou, Kyriacos A.

    2012-01-01

    A persistent hurdle in the field of tissue regeneration is to produce tissues with biochemical and biomechanical properties robust enough to meet the aggressive physiological demands of the native milieu. In an effort to improve these properties, tissues grown in vitro are often subjected to mechanical stimuli that aim to recapitulate in vivo physiology. These mechanical stimuli are thought to produce downstream alterations in intracellular ion concentrations, which ultimately give rise to increased biosynthesis. There is mounting evidence that these perturbations in the cellular microenvironment are regulated by the Ca(2+)-permeable transient receptor potential vanilloid 4 (TRPV4) channel. In this study, we examined the effects of targeted TRPV4 activation on self-assembled articular cartilage constructs. The objectives of this study were 1) to determine whether TRPV4 activation would enhance self-assembled constructs, 2) to identify an optimal treatment time window for TRPV4 activation, and 3) to compare TRPV4 activation to Na(+)/K(+) pump inhibition, which has been shown previously to improve construct tensile properties. This study employed a two-phased approach. In Phase I, self-assembled constructs were grown for 4 weeks and subjected to treatment with the TRPV4 agonist 4alpha-phorbol-12,13-didecanoate (4alpha-PDD) during three treatment time windows: t=6-10 days, t=10-14 days, and t=14-18 days. Treatment during t=10-14 days produced an 88% increase in collagen and a 153% increase in tensile stiffness. This treatment window was carried forward to Phase II. In Phase II, we performed a head-to-head comparison between TRPV4 activation using 4alpha-PDD and Na(+)/K(+) pump inhibition using ouabain. Treatment with 4alpha-PDD produced improvements on par with ouabain (91% to 107% increases in tensile stiffness). The results of this study demonstrate the effectiveness of ion channel modulation as a strategy for improving engineered tissues. To our knowledge, this is

  16. Lasing properties of active medium based on sulforhodamine 101 incorporated into commercial polyurethane compound

    SciTech Connect

    Nikolaev, S V; Pozhar, V V; Dzyubenko, M I

    2011-01-24

    The lasing properties of polymer matrices based on commercial polyurethane compound activated by sulforhodamine 101 dye are studied. Lasing with an efficiency of 26 % and pulse energy of 76 mJ is obtained using microsecond transverse pumping at a wavelength of 587 nm. The service life (time of operation to a decrease in the output energy by 50 % upon excitation by 0.3 J cm{sup -2} pulses) amounts to 2500 pulses. A particular attention is given to the bichromatic lasing spectra of the samples tested. Based on the experimental data a model explaining the two-band emission spectrum is proposed and discussed. (lasers and amplifiers)

  17. Influence of Space-Flight Factors on the Properties of Microorganisms, Producers of Biologically Active Substances

    NASA Astrophysics Data System (ADS)

    Krasheninnikova, T. K.; Kanaeva, E. N.; Ukraintsev, A. D.; Smolyanaya, G. L.; Kuznetsov, N. V.; Panasyuk, M. I.; Shcherbakov, G. Ya.

    2001-07-01

    The following substances were isolated under the influence of space-flight factors in cosmic experiments aboard the Mirorbital station: an MIB-90 monoisolant, which is distinguished by its morphological and biochemical properties and enhanced productivity, was isolated from the Bacillus thuringiensis ssp. Kurstaki var. Z-52culture, which is a producer of the plant protection agent Lepidocide; and MIA-74 and MIP-89 monoisolants, which are highly active toward heavy petroleum fractions (C23 C33), were isolated from the Arthrobacter OC-1culture, which is a producer of biodegradants for petroleum.

  18. Non-Ideal Detonation Properties of Ammonium Nitrate and Activated Carbon Mixtures

    NASA Astrophysics Data System (ADS)

    Miyake, Atsumi; Echigoya, Hiroshi; Kobayashi, Hidefumi; Ogawa, Terushige; Katoh, Katsumi; Kubota, Shiro; Wada, Yuji; Ogata, Yuji

    To obtain a better understanding of detonation properties of ammonium nitrate (AN) and activated carbon (AC) mixtures, steel tube tests with several diameters were carried out for various compositions of powdered AN and AC mixtures and the influence of the charge diameter on the detonation velocity was investigated. The results showed that the detonation velocity increased with the increase of the charge diameter. The experimentally observed values were far below the theoretically predicted values made by the thermodynamic CHEETAH code and they showed so-called non-ideal detonation. The extrapolated detonation velocity of stoichiometric composition to the infinite diameter showed a good agreement with the theoretical value.

  19. Luminescence properties of some double-activated zinc-sulphide-type phosphors

    NASA Astrophysics Data System (ADS)

    Popovici, Elisabeth-Jeanne; Aneculaese, Maria; Ursu, Veronica

    1998-07-01

    Silver and copper double activated phosphor samples were synthesized from zinc sulphide prepared by thiosulphate method and with a NaCl-MgCl2 mixture as flux. The thermal treatment was performed in a protective atmosphere at 900 - 1100 degree(s)C. The samples were characterized by crystalline structure (XRD patterns) and luminescent properties (emission spectra, decay curves). An intensification effect of the copper green fluorescence by silver ions was put in evidence. Conditions for a good green emitting phosphor were established.

  20. Nanocomposites of polymers with layered inorganic nanofillers: Antimicrobial activity, thermo-mechanical properties, morphology, and dispersion

    NASA Astrophysics Data System (ADS)

    Songtipya, Ponusa

    In the first part of the thesis, polyethylene/layered silicate nanocomposites that exhibit an antimicrobial activity were synthesized and studied. Their antimicrobial activity was designed to originate from non-leaching, novel cationic modifiers---amine-based surfactants---used as the organic-modification of the fillers. Specifically, PE/organically-modified montmorillonite ( mmt) nanocomposites were prepared via melt-processing, and simultaneous dispersion and antimicrobial activity was designed by proper choice of the fillers' organic modification. The antimicrobial activity was measured against three micotoxinogen fungal strains (Penicillium roqueforti and claviforme, and Fusarium graminearum ). Various mmt-based organofillers, which only differ in the type or amount of their organic modification, were used to exemplify how these surfactants can be designed to render antifungal activity to the fillers themselves and the respective nanocomposites. A comparative discussion of the growth of fungi on unfilled PE and nanocomposite PE films is used to demonstrate how the antimicrobial efficacy is dictated by the surfactant chemistry and, further, how the nanocomposites' inhibitory activity compares to that of the organo-fillers and the surfactants. An attempt to improve the thermomechanical reinforcement of PE/mmt nanocomposites while maintaining their antimicrobial activity, was also carried out by combining two different organically modified montmorillonites. However, a uniform microscopic dispersion could not be achieved through this approach. In the second part of this thesis, a number of fundamental studies relating to structure-property relations in nanocomposites were carried out, towards unveiling strategies that can concurrently optimize selected properties of polymers by the addition of nanofillers. Specifically, the dispersion-crystallinity-reinforcement relations in HDPE/mmt nanocomposites was investigated. The influence of a functional HDPE compatibilizer

  1. Motor units in incomplete spinal cord injury: electrical activity, contractile properties and the effects of biofeedback.

    PubMed

    Stein, R B; Brucker, B S; Ayyar, D R

    1990-10-01

    The electrical and contractile properties of hand muscles in a selected population of quadriplegic subjects were studied intensively before and after EMG biofeedback. Spontaneously active motor units and units that could only be slowly and weakly activated were observed in these subjects, in addition to units that were voluntarily activated normally. This suggests a considerable overlap of surviving motor neurons to a single muscle that are below, near or above the level of a lesion. Despite the common occurrence of polyphasic potentials and other signs of neuromuscular reinnervation, the average twitch tension of single motor units in hand muscles of quadriplegic subjects was not significantly different from that in control subjects. Nor did it increase after biofeedback training that typically increased the peak surface EMG by a factor of 2-5 times. The percentage of spontaneously active units was also constant. The surface EMG may be increased during biofeedback by using higher firing rates in motor units that can already be activated, rather than by recruiting previously unavailable motor units. PMID:2266370

  2. Physicochemical properties and antioxidant activities of polysaccharide from floral mushroom cultivated in Huangshan Mountain.

    PubMed

    Wang, Jun-Hui; Xu, Jin-Long; Zhang, Jing-Cheng; Liu, Yong; Sun, Han-Ju; Zha, Xueqiang

    2015-10-20

    In this paper, a polysaccharide fraction (FMPS) was purified from the floral mushroom cultivated in Huangshan Mountain for the first time. Physicochemical properties and antioxidant activities of FMPS were investigated. FMPS had an average molecular weight of 7.2×10(5)Da and was composed of glucose. On the basis of FT-IR, NMR and methylation analysis, the repeating unit of FMPS was established as (1→3)-linked β-d-glucopyranosyl backbone with 1-linked β-d-glucopyranosyl branches substituted at O-6 position of (1→3)-linked β-d-glucopyranosyl residues. The advanced structure studies indicated that FMPS was a triple-helical polysaccharide. The main hydrodynamic radius (Rh) of FMPS was 23.4nm and it could form a stable system with water in 1.2×10(-2)g/mL solutions. In addition, FMPS exhibited high DPPH radical scavenging activities (79.46% at 5mg/mL) and hydroxyl radical scavenging activities (74.18% at 5mg/mL), as well as Fe(2+)chelating activities and ABTS radical scavenging activities to some extent. PMID:26256181

  3. Physicochemical properties and antioxidant activities of polysaccharide from floral mushroom cultivated in Huangshan Mountain.

    PubMed

    Wang, Jun-Hui; Xu, Jin-Long; Zhang, Jing-Cheng; Liu, Yong; Sun, Han-Ju; Zha, Xueqiang

    2015-10-20

    In this paper, a polysaccharide fraction (FMPS) was purified from the floral mushroom cultivated in Huangshan Mountain for the first time. Physicochemical properties and antioxidant activities of FMPS were investigated. FMPS had an average molecular weight of 7.2×10(5)Da and was composed of glucose. On the basis of FT-IR, NMR and methylation analysis, the repeating unit of FMPS was established as (1→3)-linked β-d-glucopyranosyl backbone with 1-linked β-d-glucopyranosyl branches substituted at O-6 position of (1→3)-linked β-d-glucopyranosyl residues. The advanced structure studies indicated that FMPS was a triple-helical polysaccharide. The main hydrodynamic radius (Rh) of FMPS was 23.4nm and it could form a stable system with water in 1.2×10(-2)g/mL solutions. In addition, FMPS exhibited high DPPH radical scavenging activities (79.46% at 5mg/mL) and hydroxyl radical scavenging activities (74.18% at 5mg/mL), as well as Fe(2+)chelating activities and ABTS radical scavenging activities to some extent.

  4. A dicopper complex with distant metal centers. Structure, magnetic properties, electrochemistry and catecholase activity.

    PubMed

    Gasque, Laura; Ugalde-Saldívar, Víctor Manuel; Membrillo, Ingrid; Olguín, Juan; Mijangos, Edgar; Bernès, Sylvain; González, Ignacio

    2008-01-01

    The crystal structure and magnetic properties of a dinuclear copper(II) complex of the ligand [2,8-dimethyl-5,11-di-(dimethylethyleneamine) 1,4,5,6,7,10,11,12-octahydroimidazo [4,5-h] imidazo [4,5-c] [1,6]diazecine] dimeim have been investigated. Also, its catecholase activity has been explored in different solvent mixtures: MeCN/H2O and OH/H2O, each at several pH values. In CH3OH/H2O, where the activity was superior, the optimal pH value for the catalytic activity was found to be lower than in CH3CN/H2O. The study of the complex's electrochemical behavior (cyclic voltammetry) which was also investigated in these various media, revealed that although an increase in pH in both solvent mixtures results in an increase both in Me oxidizing power (E(1/2)) and reversibility (ipa/ipc) the change of solvent system seems to be a more influencing factor. The superior catalytic activity found in MeOH/H2O pH=8.0, is associated with a significantly more reversible behavior displayed in this medium. Potentiometric determination of the overall formation constant and three successive pKas for the complex, suggest the formation of stable hydroxo complexes which could be the catalytically active species.

  5. Relationship between electronic properties and drug activity of seven quinoxaline compounds: A DFT study

    NASA Astrophysics Data System (ADS)

    Behzadi, Hadi; Roonasi, Payman; Assle taghipour, Khatoon; van der Spoel, David; Manzetti, Sergio

    2015-07-01

    The quantum chemical calculations at the DFT/B3LYP level of theory were carried out on seven quinoxaline compounds, which have been synthesized as anti-Mycobacterium tuberculosis agents. Three conformers were optimized for each compound and the lowest energy structure was found and used in further calculations. The electronic properties including EHOMO, ELUMO and related parameters as well as electron density around oxygen and nitrogen atoms were calculated for each compound. The relationship between the calculated electronic parameters and biological activity of the studied compounds were investigated. Six similar quinoxaline derivatives with possible more drug activity were suggested based on the calculated electronic descriptors. A mechanism was proposed and discussed based on the calculated electronic parameters and bond dissociation energies.

  6. Evaluation of toxicological properties and photodynamic activity of Photolon ointment: an experimental study

    NASA Astrophysics Data System (ADS)

    Shliakhtsin, Siarhei V.; Trukhachova, Tatsiana V.; Istomin, Yuriy P.; Dunetz, Ludmila N.; Kuvshinov, Andrey V.; Naumovich, Semen A.

    2009-06-01

    The purpose of the present study was to evaluate toxicological properties and photodynamic activity of a new ready form of the photosensitizer Photolon (Fotolon) - an ointment for topical use. The data obtained show the use of topicaly applied photosensitizer provides sufficient penetration and accumulation of the active compound in tumor tissue as well as in affected periodontal tissues for the effective PDT. There are several advantages of PDT with topical application of the photosensitizer such as absence of systemic toxic and photosensitive reactions, relatively low cost of the treatment and etc. We have shown that PDT of affected periodontal tissues with local application of Photolon/Fotolon ointment provides an ability of local destruction of microbial cell, located as on the gum surface as in the spatium intercellulare what is extremely important for successful treatment of acute and chronic periodontitis.

  7. Predicting the DPP-IV inhibitory activity pIC₅₀ based on their physicochemical properties.

    PubMed

    Gu, Tianhong; Yang, Xiaoyan; Li, Minjie; Wu, Milin; Su, Qiang; Lu, Wencong; Zhang, Yuhui

    2013-01-01

    The second development program developed in this work was introduced to obtain physicochemical properties of DPP-IV inhibitors. Based on the computation of molecular descriptors, a two-stage feature selection method called mRMR-BFS (minimum redundancy maximum relevance-backward feature selection) was adopted. Then, the support vector regression (SVR) was used in the establishment of the model to map DPP-IV inhibitors to their corresponding inhibitory activity possible. The squared correlation coefficient for the training set of LOOCV and the test set are 0.815 and 0.884, respectively. An online server for predicting inhibitory activity pIC50 of the DPP-IV inhibitors as described in this paper has been given in the introduction.

  8. ALD Functionalized Nanoporous Gold: Thermal Stability, Mechanical Properties, and Catalytic Activity

    SciTech Connect

    Biener, M M; Biener, J; Wichmann, A; Wittstock, A; Baumann, T F; Baeumer, M; Hamza, A V

    2011-03-24

    Nanoporous metals have many technologically promising applications but their tendency to coarsen limits their long-term stability and excludes high temperature applications. Here, we demonstrate that atomic layer deposition (ALD) can be used to stabilize and functionalize nanoporous metals. Specifically, we studied the effect of nanometer-thick alumina and titania ALD films on thermal stability, mechanical properties, and catalytic activity of nanoporous gold (np-Au). Our results demonstrate that even only one-nm-thick oxide films can stabilize the nanoscale morphology of np-Au up to 1000 C, while simultaneously making the material stronger and stiffer. The catalytic activity of np-Au can be drastically increased by TiO{sub 2} ALD coatings. Our results open the door to high temperature sensor, actuator, and catalysis applications and functionalized electrodes for energy storage and harvesting applications.

  9. Modulation of Activity Profiles for Largazole-Based HDAC Inhibitors through Alteration of Prodrug Properties

    PubMed Central

    2014-01-01

    Largazole is a potent and class I-selective histone deacetylase (HDAC) inhibitor purified from marine cyanobacteria and was demonstrated to possess antitumor activity. Largazole employs a unique prodrug strategy, via a thioester moiety, to liberate the bioactive species largazole thiol. Here we report alternate prodrug strategies to modulate the pharmacokinetic and pharmacodynamics profiles of new largazole-based compounds. The in vitro effects of largazole analogues on cancer cell proliferation and enzymatic activities of purified HDACs were comparable to the natural product. However, in vitro and in vivo histone hyperacetylation in HCT116 cells and implanted tumors, respectively, showed differences, particularly in the onset of action and oral bioavailability. These results indicate that, by employing a different approach to disguise the “warhead” moiety, the functional consequence of these prodrugs can be significantly modulated. Our data corroborate the role of the pharmacokinetic properties of this class of compounds to elicit the desired and timely functional response. PMID:25147612

  10. ALD functionalized nanoporous gold: thermal stability, mechanical properties, and catalytic activity.

    PubMed

    Biener, Monika M; Biener, Juergen; Wichmann, Andre; Wittstock, Arne; Baumann, Theodore F; Bäumer, Marcus; Hamza, Alex V

    2011-08-10

    Nanoporous metals have many technologically promising applications, but their tendency to coarsen limits their long-term stability and excludes high temperature applications. Here, we demonstrate that atomic layer deposition (ALD) can be used to stabilize and functionalize nanoporous metals. Specifically, we studied the effect of nanometer-thick alumina and titania ALD films on thermal stability, mechanical properties, and catalytic activity of nanoporous gold (np-Au). Our results demonstrate that even only 1 nm thick oxide films can stabilize the nanoscale morphology of np-Au up to 1,000°C, while simultaneously making the material stronger and stiffer. The catalytic activity of np-Au can be drastically increased by TiO(2) ALD coatings. Our results open the door to high-temperature sensor, actuator, and catalysis applications and functionalized electrodes for energy storage and harvesting applications.

  11. Characterisation of Drosophila CMP-sialic acid synthetase activity reveals unusual enzymatic properties

    PubMed Central

    Mertsalov, Ilya B.; Novikov, Boris N.; Scott, Hilary; Dangott, Lawrence; Panin, Vladislav M.

    2016-01-01

    CMP-sialic acid synthetase (CSAS) is a key enzyme of the sialylation pathway. CSAS produces the activated sugar donor, CMP-sialic acid, which serves as a substrate for sialyltransferases to modify glycan termini with sialic acid. Unlike other animal CMP-Sia synthetases that normally localize in the nucleus, Drosophila melanogaster CSAS (DmCSAS) localizes in the cell secretory compartment, predominantly in the Golgi, which suggests that this enzyme has properties distinct from those of its vertebrate counterparts. To test this hypothesis, we purified recombinant DmCSAS and characterised its activity in vitro. Our experiments revealed several unique features of this enzyme. DmCSAS displays specificity for N-acetylneuraminic acid as a substrate, shows preference for lower pH and can function with a broad range of metal cofactors. When tested at a pH corresponding to the Golgi compartment, the enzyme showed significant activity with several metal cations, including Zn2+, Fe2+, Co2+ and Mn2+, while the activity with Mg2+ was found to be low. Protein sequence analysis and site-specific mutagenesis identified an aspartic acid residue that is necessary for enzymatic activity and predicted to be involved in coordinating a metal cofactor. DmCSAS enzymatic activity was found to be essential in vivo for rescuing the phenotype of DmCSAS mutants. Finally, our experiments revealed a steep dependence of the enzymatic activity on temperature. Taken together, our results indicate that DmCSAS underwent evolutionary adaptation to pH and ionic environment different from that of counterpart synthetases in vertebrates. Our data also suggest that environmental temperatures can regulate Drosophila sialylation, thus modulating neural transmission. PMID:27114558

  12. The influence comparing of activated biochar and conventional biochar on the soil biological properties

    NASA Astrophysics Data System (ADS)

    Dvořáčková, Helena; Mykajlo, Irina; Záhora, Jaroslav

    2016-04-01

    In our experiment we have used biochar. This material is the product of the pyrolysis that has shown a positive effect on numerous physical and chemical soil properties. However, its influence on the biological component of the soil is very variable. A number of toxic substances that inhibit the soil productivity may be produced during pyrolysis process. The experiment dealt with the hypothesis concerning biochar toxicity reduction by simulating natural processes in the soil. Biochar has been exposed to aeration in the aquatic environment, enriched with nutrients and a source of native soil microflora. It has been created 6 variants in total, each with four replications. The soils samples have been placed in a phytotron for 90 days. Variants consisted of the soil with fertilizers adding (compost, biochar, activated biochar) and have been prepared as well as variants containing compost and biochar and activated biochar optionally. The highest aboveground biomass production has been estimated in variants containing compost, while the lowest production - in the variants containing conventional biochar. During production comparing of the variants with the conventional biochar, activated biochar and control samples it has been evident that activated biochar promotes plant growth, and in contradiction conventional biochar inhibits it. We will approach to the same conclusions when comparing variants with a combination of conventional biochar + compost and activated biochar + compost. Mineral nitrogen leaching has been another investigated parameter. The highest leaching has occurred in the control variant, while the lowest - in the variant with activated biochar (the leaching of nitrate nitrogen has been negligeable). Our results suggest that activated biochar has the potential; however, it is necessary to carry out similar experiments in the field conditions.

  13. Fab-based bispecific antibody formats with robust biophysical properties and biological activity.

    PubMed

    Wu, Xiufeng; Sereno, Arlene J; Huang, Flora; Lewis, Steven M; Lieu, Ricky L; Weldon, Caroline; Torres, Carina; Fine, Cody; Batt, Micheal A; Fitchett, Jonathan R; Glasebrook, Andrew L; Kuhlman, Brian; Demarest, Stephen J

    2015-01-01

    A myriad of innovative bispecific antibody (BsAb) platforms have been reported. Most require significant protein engineering to be viable from a development and manufacturing perspective. Single-chain variable fragments (scFvs) and diabodies that consist only of antibody variable domains have been used as building blocks for making BsAbs for decades. The drawback with Fv-only moieties is that they lack the native-like interactions with CH1/CL domains that make antibody Fab regions stable and soluble. Here, we utilize a redesigned Fab interface to explore 2 novel Fab-based BsAbs platforms. The redesigned Fab interface designs limit heavy and light chain mixing when 2 Fabs are co-expressed simultaneously, thus allowing the use of 2 different Fabs within a BsAb construct without the requirement of one or more scFvs. We describe the stability and activity of a HER2×HER2 IgG-Fab BsAb, and compare its biophysical and activity properties with those of an IgG-scFv that utilizes the variable domains of the same parental antibodies. We also generated an EGFR × CD3 tandem Fab protein with a similar format to a tandem scFv (otherwise known as a bispecific T cell engager or BiTE). We show that the Fab-based BsAbs have superior biophysical properties compared to the scFv-based BsAbs. Additionally, the Fab-based BsAbs do not simply recapitulate the activity of their scFv counterparts, but are shown to possess unique biological activity.

  14. Determination of Interfacial Properties by Surface Active Impurities in an Organic Waste Liquid

    NASA Astrophysics Data System (ADS)

    Hsu, H.; Demond, A. H.

    2001-12-01

    Wettability and interfacial tension play an important role in governing the transport and distribution of the organic contaminants in the vadose zone. Organic liquids, like waste tetrachloroethylene (PCE) or gasoline, contain surface active impurities that alter the interfacial properties and, in some cases, invert the wettability depending on the pH which is controlled by the geochemistry of the system. Most studies looking at interfacial property changes utilize a single surface active impurity, while this study seeks to understand the behavior of a binary surfactant system. Individually, octanoic acid (OA) does not alter the wettability of quartz since it exists only in a netural or anionic form and cannot sorb to the negatively charged quartz surface. Dodecylamine (DDA), in its cationic form, sorbs to quartz and changes the contact angle from 5¡V70 degree, but the surface remains weakly water wetting. However, a mixture of the two changes quartz to oil wet, giving a contact angle of up to 130 degree. Similarly, the interfacial tension decreases in the mixtures more than expected based on the individual behavior of the compounds. An anionic-cationic surfactant complex is proposed to account for the change. Evidence to support this species is based on comparing the equilibrium pH values of several OA/DDA aqueous solutions with the expected pH values assuming no mutual interaction. The discrepancy between these two sets of pH values suggests that a positive-charged surfactant complex forms that may sorb on quartz. Taken together, these data show the role of pH in the formation of a hydrophobic cationic-anionic surface-active complex, and point to the importance of the synergy between geochemistry and the surface-active solutes.

  15. Barrier properties of poly(vinyl alcohol) membranes containing carbon nanotubes or activated carbon.

    PubMed

    Surdo, Erin M; Khan, Iftheker A; Choudhury, Atif A; Saleh, Navid B; Arnold, William A

    2011-04-15

    Carbon nanotube addition has been shown to improve the mechanical properties of some polymers. Because of their unique adsorptive properties, carbon nanotubes may also improve the barrier performance of polymers used in contaminant containment. This study compares the barrier performance of poly(vinyl alcohol) (PVA) membranes containing single-walled carbon nanotubes (SWCNTs) to that for PVA containing powdered activated carbon (PAC). Raw and surface-functionalized versions of each sorbent were tested for their abilities to adsorb 1,2,4-trichlorobenzene and Cu(2+), representing the important hydrophobic organic and heavy metal contaminant classes, as they diffused across the PVA. In both cases, PAC (for 1,2,4-trichlorobenzene) and functionalized PAC (for Cu(2+)) outperformed SWCNTs on a per mass basis by trapping more of the contaminants within the barrier membrane. Kinetics of sorption are important in evaluating barrier properties, and poor performance of SWCNT-containing membranes as 1,2,4-TCB barriers is attributed to kinetic limitations. PMID:21349636

  16. From tunable core-shell nanoparticles to plasmonic drawbridges: Active control of nanoparticle optical properties

    PubMed Central

    Byers, Chad P.; Zhang, Hui; Swearer, Dayne F.; Yorulmaz, Mustafa; Hoener, Benjamin S.; Huang, Da; Hoggard, Anneli; Chang, Wei-Shun; Mulvaney, Paul; Ringe, Emilie; Halas, Naomi J.; Nordlander, Peter; Link, Stephan; Landes, Christy F.

    2015-01-01

    The optical properties of metallic nanoparticles are highly sensitive to interparticle distance, giving rise to dramatic but frequently irreversible color changes. By electrochemical modification of individual nanoparticles and nanoparticle pairs, we induced equally dramatic, yet reversible, changes in their optical properties. We achieved plasmon tuning by oxidation-reduction chemistry of Ag-AgCl shells on the surfaces of both individual and strongly coupled Au nanoparticle pairs, resulting in extreme but reversible changes in scattering line shape. We demonstrated reversible formation of the charge transfer plasmon mode by switching between capacitive and conductive electronic coupling mechanisms. Dynamic single-particle spectroelectrochemistry also gave an insight into the reaction kinetics and evolution of the charge transfer plasmon mode in an electrochemically tunable structure. Our study represents a highly useful approach to the precise tuning of the morphology of narrow interparticle gaps and will be of value for controlling and activating a range of properties such as extreme plasmon modulation, nanoscopic plasmon switching, and subnanometer tunable gap applications. PMID:26665175

  17. Structural similarity based kriging for quantitative structure activity and property relationship modeling.

    PubMed

    Teixeira, Ana L; Falcao, Andre O

    2014-07-28

    Structurally similar molecules tend to have similar properties, i.e. closer molecules in the molecular space are more likely to yield similar property values while distant molecules are more likely to yield different values. Based on this principle, we propose the use of a new method that takes into account the high dimensionality of the molecular space, predicting chemical, physical, or biological properties based on the most similar compounds with measured properties. This methodology uses ordinary kriging coupled with three different molecular similarity approaches (based on molecular descriptors, fingerprints, and atom matching) which creates an interpolation map over the molecular space that is capable of predicting properties/activities for diverse chemical data sets. The proposed method was tested in two data sets of diverse chemical compounds collected from the literature and preprocessed. One of the data sets contained dihydrofolate reductase inhibition activity data, and the second molecules for which aqueous solubility was known. The overall predictive results using kriging for both data sets comply with the results obtained in the literature using typical QSPR/QSAR approaches. However, the procedure did not involve any type of descriptor selection or even minimal information about each problem, suggesting that this approach is directly applicable to a large spectrum of problems in QSAR/QSPR. Furthermore, the predictive results improve significantly with the similarity threshold between the training and testing compounds, allowing the definition of a confidence threshold of similarity and error estimation for each case inferred. The use of kriging for interpolation over the molecular metric space is independent of the training data set size, and no reparametrizations are necessary when more compounds are added or removed from the set, and increasing the size of the database will consequentially improve the quality of the estimations. Finally it is shown

  18. PREDICTING THE ADSORPTION CAPACITY OF ACTIVATED CARBON FOR EMERGING ORGANIC CONTAMINANTS FROM FUNDAMENTAL ADSORBENT AND ADSORBATE PROPERTIES - PRESENTATION

    EPA Science Inventory

    A quantitative structure-property relationship (QSPR) was developed and combined with the Polanyi-Dubinin-Manes model to predict adsorption isotherms of emerging contaminants on activated carbons with a wide range of physico-chemical properties. Affinity coefficients (βl

  19. 41 CFR 102-75.130 - If hazardous substance activity took place on the property, what specific information must an...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... substance activity took place on the property, the reporting agency must include information on the type and.... The reporting agency must also advise the disposal agency if all remedial action necessary to protect... the date the property was reported excess. If such action was not taken, the reporting agency...

  20. Synthesis, physicochemical properties of allopurinol derivatives and their biological activity against Trypanosoma cruzi.

    PubMed

    Raviolo, M A; Solana, M E; Novoa, M M; Gualdesi, M S; Alba-Soto, C D; Briñón, M C

    2013-11-01

    Chagas disease is caused by Trypanosoma cruzi (T. cruzi) leading to a huge number of infections and deaths per year, because in addition to many sufferers only having limited access to health services only an inefficient chemotherapy is available using drugs such as benznidazole and nifurtimox. Here, C6-alkyl (2a-c) and N1-acyl (3a-c) derivatives of Allopurinol (Allop, compound with activity against T. cruzi) were synthesized in good yields and their structures were unambiguously characterized. Only 2a, 2b and 3c showed inhibitory activity against the proliferative stages of the parasite when tested at 1 μg mL(-1) with the 3c derivative exhibiting an IC50 value similar to that of Allop and not being toxic for mammalian cells. Relevant pharmaceutical physicochemical properties (pKa, stability, solubility, lipophilicity) were also determined as well by using Lipinski's rule, polar surface area and molecular rigidity. Taken together, the results demonstrated that the studied derivatives had optimal properties for bioavailability and oral absorption. For the stability studies, Micellar Liquid Chromatography was used as the analytical method which was fully validated according to the FDA guidelines and shown to be a suitable, sensitive and simple method for routine analysis of these Allop derivatives.

  1. Differences in spectral absorption properties between active neovascular macular degeneration and mild age related maculopathy.

    PubMed

    Balaskas, Konstantinos; Nourrit, Vincent; Dinsdale, Michelle; Henson, David B; Aslam, Tariq

    2013-05-01

    This study examines the differences in spectral absorption properties between the maculae of patients with active neovascular macular degeneration and those with early age related maculopathy (ARM). Patients attending for management of neovascular age related macular degeneration (AMD) underwent multispectral imaging with a system comprising of a modified digital fundus camera coupled with a 250-W tungsten-halogen lamp and a liquid crystal fast-tuneable filter. Images were obtained at 8 wavelengths between 496 and 700 nm. Aligned images were used to generate a DLA (differential light absorption, a measure of spectral absorption properties) map of the macular area. DLA maps were generated for both eyes of 10 sequential patients attending for anti-vascular endothelial growth factor injections. Each of these patients had active leaking neovascular AMD in one eye and early ARM or milder disease in the fellow eye. Eyes with neovascular AMD demonstrated lower average levels of DLA compared with their fellow eyes with early ARM (p=0.037, t test). The significant difference in DLA demonstrates the potential of multispectral imaging for differentiating the two pathologies non-invasively. PMID:23137662

  2. Cloning, heterologous expression and properties of a recombinant active turnip peroxidase.

    PubMed

    Rodriguez-Cabrera, Norma A; Regalado, C; Garcia-Almendarez, Blanca E

    2011-07-13

    Turnip (Brassica napus) roots peroxidase isoforms have been used in diagnostic kits and can also efficiently polymerize phenolic compounds from wastewaters. Heterologous expression of a turnip acidic peroxidase (BnPA) was investigated to increase availability of this widely used enzyme. The mature BnPA was ligated into the pET28a(+) vector and used to transform Escherichia coli Rosetta 2. Recombinant BnPA peroxidase was overexpressed and accumulated in inclusion bodies from which it was purified to homogeneity by immobilized metal affinity chromatography under denaturing conditions. Peroxidase activity was observed after a refolding process under oxidative conditions. The yield of pure recombinant BnPA was 29 mg L(-1) of culture with a specific activity of 981 ± 20 ABTS units mg(-1) at optimal conditions (pH 6, 45 °C). Recombinant BnPA showed similar kinetic properties compared to native turnip peroxidase, and its secondary structure evaluated by circular dichroism comprised 20% α-helix, 32% β-sheet and 48% random structure. Recombinant BnPA showed high yield and good kinetic properties which are key steps for future structure-function studies and biotechnological applications. PMID:21591783

  3. Elution kinetics, antimicrobial activity, and mechanical properties of 11 different antibiotic loaded acrylic bone cement.

    PubMed

    Gálvez-López, Ruben; Peña-Monje, Alejandro; Antelo-Lorenzo, Ramón; Guardia-Olmedo, Juan; Moliz, Juan; Hernández-Quero, José; Parra-Ruiz, Jorge

    2014-01-01

    Antibiotic-loaded acrylic bone cements (ALABC) spacers are routinely used in the treatment of prosthetic joint infections. The objectives of our study were to evaluate different ALABC for elution kinetics, thermal stability, and mechanical properties. A 10 or 20% mixture (w/w) beads of medium viscosity bone cement (DePuy, Inc) and vancomycin (VAN), gentamycin (GM), daptomycin (DAP), moxifloxacin (MOX), rifampicin (RIF), cefotaxime (CTX), cefepime (FEP), amoxicillin clavulanate (AmC), ampicillin (AMP), meropenem (MER), and ertapenem (ERT) were formed and placed into wells filled with phosphate-buffered saline. Antibiotic concentrations were determined using high-performance liquid chromatography. Antimicrobial activity was tested against Micrococcus luteus ATCC 9341 or Escherichia coli ATCC 25922. AmC, AMP, and FEP concentration rapidly decreased after day 2, being almost undetectable at day 4. Sustained and high elution rates were observed with VAN, GM, MOX, and RIF for the 30-day duration of the experiment. DAP, MER, ERT, and CTX elution rates constantly decreased from day 4. All antibiotics tested retained antimicrobial activity proving thermal stability. Mechanical properties of ALABC were maintained except when RIF was used. PMID:24231380

  4. New Luminescent Polynuclear Metal Complexes with Anticancer Properties: Toward Structure-Activity Relationships.

    PubMed

    Wenzel, Margot; de Almeida, Andreia; Bigaeva, Emilia; Kavanagh, Paul; Picquet, Michel; Le Gendre, Pierre; Bodio, Ewen; Casini, Angela

    2016-03-01

    A series of new heterodinuclear luminescent complexes with two different organic ligands have been synthesized and characterized. A luminescent Ru(II)(polypyridine) moiety and a metal-based anticancer fragment (AuCl, (p-cymene)RuCl2, (p-cymene)OsCl2, (Cp*)RhCl2, or Au-thioglucose) are the two general features of these complexes. All of the bimetallic compounds have been evaluated for their antiproliferative properties in vitro in human cancer cell lines. Only the complexes containing an Au(I) fragment exhibit antiproliferative activity in the range of cisplatin or higher. The photophysical and electrochemical properties of the bimetallic species have been investigated, and fluorescence microscopy experiments have been performed successfully. The most promising bimetallic cytotoxic complexes (i.e., with the Au-thioglucose scaffold) have shown to be easily taken up by cancer cells at 37 °C in the cytoplasm or in specific organelles. Interestingly, experiments repeated at 4 °C showed no uptake of the bimetallic species inside cells, which confirms involvement of active transport processes. To evaluate the role of glucose transporters in the cell uptake of the gold complexes, inhibition of the GluT-1 (glucose transporter isoform with high level of expression in cancer cells) was achieved, showing only scarce influence on the compounds' uptake. Finally, the observed absence of interactions with nucleic acid model structures suggests that the gold compounds may have different intracellular targets with respect to cisplatin.

  5. Antioxidant properties, autooxidation, and mutagenic activity of echinochrome a compared with its etherified derivative.

    PubMed

    Lebedev, A V; Levitskaya, E L; Tikhonova, E V; Ivanova, M V

    2001-08-01

    Antioxidant properties of 2,3,5,7,8-pentahydroxy-6-ethyl-1,4-naphthoquinone (echinochrome A) were linked with the scavenging of peroxy radicals in liposomes, trapping of superoxide anion radicals, and binding of ferrous ions to inactive complexes in the aqueous phase. The antioxidant property of 6-ethyl-2,3,7-trimethoxy-5,8-dihydroxy-1,4-naphthoquinone (trimethoxyechinochrome A) was negligible. Autooxidation of echinochrome A was increased in basic media according to the degree of its dissociation. Autooxidation of polyvalent anions in basic media was accompanied by generation of naphthosemiquinone and superoxide anion radicals as free radical intermediates. An increased rate of echinochrome A autooxidation was noted in the presence of calcium ions. This was explained by a shift of pK of Ca2+-echinochrome A complexes toward acidic pH comparably with echinochrome A. Echinochrome A possessed pronounced mutagenic activity, while trimethoxyechinochrome A was inactive in the Salmonella/mammalian microsome reverse mutation assay (Ames test) for all examined cells (TA98, TA100, TA1537). Comparison of the chemical and biological activity of echinochrome A and trimethoxyechinochrome A demonstrated the key role of the beta-hydroxyl groups in the 2nd, 3rd, and 7th naphthol cycle positions. The O2-* and naphthosemiquinone radicals generated in the redox transition of 2,3-oxygroups may be the reason for the strongly pronounced mutagenicity of echinochrome A. PMID:11566058

  6. Elution kinetics, antimicrobial activity, and mechanical properties of 11 different antibiotic loaded acrylic bone cement.

    PubMed

    Gálvez-López, Ruben; Peña-Monje, Alejandro; Antelo-Lorenzo, Ramón; Guardia-Olmedo, Juan; Moliz, Juan; Hernández-Quero, José; Parra-Ruiz, Jorge

    2014-01-01

    Antibiotic-loaded acrylic bone cements (ALABC) spacers are routinely used in the treatment of prosthetic joint infections. The objectives of our study were to evaluate different ALABC for elution kinetics, thermal stability, and mechanical properties. A 10 or 20% mixture (w/w) beads of medium viscosity bone cement (DePuy, Inc) and vancomycin (VAN), gentamycin (GM), daptomycin (DAP), moxifloxacin (MOX), rifampicin (RIF), cefotaxime (CTX), cefepime (FEP), amoxicillin clavulanate (AmC), ampicillin (AMP), meropenem (MER), and ertapenem (ERT) were formed and placed into wells filled with phosphate-buffered saline. Antibiotic concentrations were determined using high-performance liquid chromatography. Antimicrobial activity was tested against Micrococcus luteus ATCC 9341 or Escherichia coli ATCC 25922. AmC, AMP, and FEP concentration rapidly decreased after day 2, being almost undetectable at day 4. Sustained and high elution rates were observed with VAN, GM, MOX, and RIF for the 30-day duration of the experiment. DAP, MER, ERT, and CTX elution rates constantly decreased from day 4. All antibiotics tested retained antimicrobial activity proving thermal stability. Mechanical properties of ALABC were maintained except when RIF was used.

  7. The bacterial cytoplasm has glass-like properties and is fluidized by metabolic activity

    NASA Astrophysics Data System (ADS)

    Parry, Brad; Surovtsev, Ivan; Cabeen, Matthew; O'Hern, Corey; Dufresne, Eric; Jacobs-Wagner, Christine

    2014-03-01

    In eukaryotes, active transport involves motor proteins and cytoskeletal filaments. In contrast, bacteria (which lack cytoskeletal motor proteins) are thought to rely on diffusion for molecular transport, though the physical properties of the bacterial cytoplasm are poorly understood. Through single particle tracking of foreign particles of different sizes, we have found that the bacterial cytoplasm exhibits striking similarities to glass-forming liquids. Glass-forming liquids are noted for their metastability near the glass transition where their behavior changes from liquid-like to amorphous solid with even small perturbations. Particles of different sizes exhibit distinct dynamics and their mobility changes from fluid-like to glassy with increasing size. This size dependency provides an explanation for previous reports of both normal and anomalous diffusion in the bacterial cytoplasm. Moreover, we find that cellular metabolism attenuates the glassy properties of the bacterial cytoplasm. As a result, components that would otherwise be caged in narrow regions of confinement are able to explore the cytoplasmic space under metabolically active conditions. These findings have broad implications for our understanding of bacterial physiology as the glassy behavior of the cytoplasm impacts all intracellular processes involving large cellular components. Supported by the Howard Hughes Medical Institute.

  8. Electronic properties of environmental pollutants and their mutagenic activity: Nitro derivatives of azaphenanthrenes.

    PubMed

    Ostojić, Bojana D; Đorđević, Dragana S

    2015-09-01

    The physico-chemical properties of nitroazaphenanthrene isomers: 4-nitro-9-azaphenanthrene (4-N-9-Aph), 5-nitro-9-azaphenanthrene (5-N-9-Aph), 6-nitro-4-azaphenanthrene (6-N-4-Aph), 8-nitro-1-azaphenanthrene (8-N-1-Aph), and 8-nitro-4-azaphenanthrene (8-N-4-Aph) have been investigated theoretically using Density Functional Theory (DFT) calculations. Equilibrium geometries, relative stability, ionization potentials, electron affinities, molecular electrostatic potentials, dipole moments, electric polarizabilities, and vibrational properties of these isomers are presented. Averaged O-N-C-C dihedral angle, dipole moment, polarizability, the summation of IR intensities (∑IIR) and the summation of Raman activities (∑ARaman) over all 3N-6 vibrational degrees of freedom are sensitive to the structure of isomers. A very good linear relationship between ∑ARaman values (R=1.00) and the Salmonella typhimurium strain TA98(-S9) mutagenic activity of the investigated nitroazaphenanthrene isomers (Tokiwa et al., 2003) reveals a very important role of inductive and dispersive forces on the mutagenic pathways of the investigated isomers. PMID:25974009

  9. Pregnancy affects cellular activity, but not tissue mechanical properties, in the healing rabbit medial collateral ligament.

    PubMed

    Hart, D A; Reno, C; Frank, C B; Shrive, N G

    2000-05-01

    Recently, evidence has been accumulating that ligament and joint laxity is altered in women and rabbits during pregnancy. Furthermore, many female adolescents injure ligaments through participation in athletics and other activities. Therefore, to determine whether pregnancy has different effects on the injured and uninjured medial collateral ligament of the rabbit knee, we investigated cellular changes (mRNA levels) and alterations in tissue properties (biomechanics) accompanying pregnancy in animals with the medial collateral ligament injured during adolescence and bred for their primigravid pregnancy as young adults. Assessment of mRNA levels for matrix molecules, matrix metalloproteinases and tissue inhibitor of metalloproteinase-1, growth factors and sex hormone receptors, inflammatory cytokines, inducible nitric oxide synthase, and cyclooxygenase-2 by semiquantitative reverse transcription-polymerase chain reaction revealed that pregnancy had different impacts on scar and uninjured tissue for six of 15 genes assessed. A pregnancy-associated increase in laxity of the medial collateral ligament was observed for rabbits in the uninjured primigravida group; however, no increase was observed for injured rabbits during pregnancy. The injured ligament was already significantly more lax than the normal counterpart, and pregnancy did not lead to additional laxity or prevent the normal decline in laxity as the scar matured in nonpregnant animals. These results indicate that the impact of pregnancy on laxity and cell activity of the medial collateral ligament is dependent on whether the ligament is uninjured or injured. Pregnancy had no significant effect on structural (stiffness and failure load), material (stress at failure and Young's modulus), or viscoelastic (cyclic and static relaxation) properties of tissue from uninjured or injured medial collateral ligament. Therefore, the properties of the healing ligament were not adversely affected during pregnancy in this

  10. Correlation of Coronal Plasma Properties and Solar Magnetic Field in a Decaying Active Region

    NASA Astrophysics Data System (ADS)

    Ko, Yuan-Kuen; Young, Peter R.; Muglach, Karin; Warren, Harry P.; Ugarte-Urra, Ignacio

    2016-08-01

    We present the analysis of a decaying active region observed by the EUV Imaging Spectrometer on Hinode during 2009 December 7–11. We investigated the temporal evolution of its structure exhibited by plasma at temperatures from 300,000 to 2.8 million degrees, and derived the electron density, differential emission measure, effective electron temperature, and elemental abundance ratios of Si/S and Fe/S (as a measure of the First Ionization Potential (FIP) Effect). We compared these coronal properties to the temporal evolution of the photospheric magnetic field strength obtained from the Solar and Heliospheric Observatory Michelson Doppler Imager magnetograms. We find that, while these coronal properties all decreased with time during this decay phase, the largest change was at plasma above 1.5 million degrees. The photospheric magnetic field strength also decreased with time but mainly for field strengths lower than about 70 Gauss. The effective electron temperature and the FIP bias seem to reach a “basal” state (at 1.5 × 106 K and 1.5, respectively) into the quiet Sun when the mean photospheric magnetic field (excluding all areas <10 G) weakened to below 35 G, while the electron density continued to decrease with the weakening field. These physical properties are all positively correlated with each other and the correlation is the strongest in the high-temperature plasma. Such correlation properties should be considered in the quest for our understanding of how the corona is heated. The variations in the elemental abundance should especially be considered together with the electron temperature and density.

  11. Correlation of Coronal Plasma Properties and Solar Magnetic Field in a Decaying Active Region

    NASA Astrophysics Data System (ADS)

    Ko, Yuan-Kuen; Young, Peter R.; Muglach, Karin; Warren, Harry P.; Ugarte-Urra, Ignacio

    2016-08-01

    We present the analysis of a decaying active region observed by the EUV Imaging Spectrometer on Hinode during 2009 December 7-11. We investigated the temporal evolution of its structure exhibited by plasma at temperatures from 300,000 to 2.8 million degrees, and derived the electron density, differential emission measure, effective electron temperature, and elemental abundance ratios of Si/S and Fe/S (as a measure of the First Ionization Potential (FIP) Effect). We compared these coronal properties to the temporal evolution of the photospheric magnetic field strength obtained from the Solar and Heliospheric Observatory Michelson Doppler Imager magnetograms. We find that, while these coronal properties all decreased with time during this decay phase, the largest change was at plasma above 1.5 million degrees. The photospheric magnetic field strength also decreased with time but mainly for field strengths lower than about 70 Gauss. The effective electron temperature and the FIP bias seem to reach a “basal” state (at 1.5 × 106 K and 1.5, respectively) into the quiet Sun when the mean photospheric magnetic field (excluding all areas <10 G) weakened to below 35 G, while the electron density continued to decrease with the weakening field. These physical properties are all positively correlated with each other and the correlation is the strongest in the high-temperature plasma. Such correlation properties should be considered in the quest for our understanding of how the corona is heated. The variations in the elemental abundance should especially be considered together with the electron temperature and density.

  12. Selective Gating of Neuronal Activity by Intrinsic Properties in Distinct Motor Rhythms.

    PubMed

    Li, Wen-Chang

    2015-07-01

    Many neural circuits show fast reconfiguration following altered sensory or modulatory inputs to generate stereotyped outputs. In the motor circuit of Xenopus tadpoles, I study how certain voltage-dependent ionic currents affect firing thresholds and contribute to circuit reconfiguration to generate two distinct motor patterns, swimming and struggling. Firing thresholds of excitatory interneurons [i.e., descending interneurons (dINs)] in the swimming central pattern generator are raised by depolarization due to the inactivation of Na(+) currents. In contrast, the thresholds of other types of neurons active in swimming or struggling are raised by hyperpolarization from the activation of fast transient K(+) currents. The firing thresholds are then compared with the excitatory synaptic drives, which are revealed by blocking action potentials intracellularly using QX314 during swimming and struggling. During swimming, transient K(+) currents lower neuronal excitability and gate out neurons with weak excitation, whereas their inactivation by strong excitation in other neurons increases excitability and enables fast synaptic potentials to drive reliable firing. During struggling, continuous sensory inputs lead to high levels of network excitation. This allows the inactivation of Na(+) currents and suppression of dIN activity while inactivating transient K(+) currents, recruiting neurons that are not active in swimming. Therefore, differential expression of these currents between neuron types can explain why synaptic strength does not predict firing reliability/intensity during swimming and struggling. These data show that intrinsic properties can override fast synaptic potentials, mediate circuit reconfiguration, and contribute to motor-pattern switching.

  13. HdeB chaperone activity is coupled to its intrinsic dynamic properties

    PubMed Central

    Ding, Jienv; Yang, Chengfeng; Niu, Xiaogang; Hu, Yunfei; Jin, Changwen

    2015-01-01

    Enteric bacteria encounter extreme acidity when passing through hosts’ stomach. Since the bacterial periplasmic space quickly equilibrates with outer environment, an efficient acid resistance mechanism is essential in preventing irreversible protein denaturation/aggregation and maintaining bacteria viability. HdeB, along with its homolog HdeA, was identified as a periplasmic acid-resistant chaperone. Both proteins exist as homodimers and share similar monomeric structures under neutral pH, while showing different dimeric packing interfaces. Previous investigations show that HdeA functions through an acid-induced dimer-to-monomer transition and partial unfolding at low pH (pH 2–3), resulting in exposure of hydrophobic surfaces that bind substrate proteins. In contrast, HdeB appears to have a much higher optimal activation pH (pH 4–5), under which condition the protein maintains a well-folded dimer and the mechanism for its chaperone activity remains elusive. Herein, we present an NMR study of HdeB to investigate its dynamic properties. Our results reveal that HdeB undergoes significant micro- to milli-second timescale conformational exchanges at neutral to near-neutral pH, under the later condition it exhibits optimal activity. The current study indicates that HdeB activation is coupled to its intrinsic dynamics instead of structural changes, and therefore its functional mechanism is apparently different from HdeA. PMID:26593705

  14. Optically active substituted polyacetylene@carbon nanotube hybrids: Preparation, characterization and infrared emissivity property study

    NASA Astrophysics Data System (ADS)

    Bu, Xiaohai; Zhou, Yuming; Zhang, Tao; Wang, Yongjuan; Zhang, Zewu; He, Man

    2014-08-01

    Optically active substituted polyacetylene@multiwalled carbon nanotubes (SPA@MWCNTs) nanohybrids were fabricated by wrapping helical SPA copolymers onto the surface of modified nanotubes through ester bonding linkage. SPA copolymer based on chiral phenylalanine and serine was pre-polymerized by a rhodium zwitterion catalyst in THF, and evidently proved to possess strong optical activity and adopt a predominately one-handed helical conformation. Various characterizations including Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) demonstrated that the SPA had been covalently grafted onto the nanotubes without destroying their original graphite structure. The wrapped SPA was found to exhibit an enhancement in thermal stability and still maintained considerable optical activity after grafting. The infrared emissivity property of the nanohybrids at 8-14 μm was investigated in addition. The results indicated that the SPA@MWCNTs hybrid matrix could possess a much lower infrared emissivity value (ε=0.707) than raw MWCNTs, which might be due to synergistic effect of the unique helical conformation of optically active SPA and strengthened interfacial interaction between the organic polymers and inorganic nanoparticles.

  15. Antiadherent and Antibiofilm Activity of Humulus lupulus L. Derived Products: New Pharmacological Properties

    PubMed Central

    Micota, Bartlomiej; Sadowska, Beata; Jedrejek, Dariusz; Wieckowska-Szakiel, Marzena

    2013-01-01

    New antimicrobial properties of products derived from Humulus lupulus L. such as antiadherent and antibiofilm activities were evaluated. The growth of gram-positive but not gram-negative bacteria was inhibited to different extents by these compounds. An extract of hop cones containing 51% xanthohumol was slightly less active against S. aureus strains (MIC range 31.2–125.0 μg/mL) than pure xanthohumol (MIC range 15.6–62.5 μg/mL). The spent hop extract, free of xanthohumol, exhibited lower but still relevant activity (MIC range 1-2 mg/mL). There were positive coactions of hop cone, spent hop extracts, and xanthohumol with oxacillin against MSSA and with linezolid against MSSA and MRSA. Plant compounds in the culture medium at sub-MIC concentrations decreased the adhesion of Staphylococci to abiotic surfaces, which in turn caused inhibition of biofilm formation. The rate of mature biofilm eradication by these products was significant. The spent hop extract at MIC reduced biofilm viability by 42.8%, the hop cone extract by 74.8%, and pure xanthohumol by 86.5%. When the hop cone extract or xanthohumol concentration was increased, almost complete biofilm eradication was achieved (97–99%). This study reveals the potent antibiofilm activity of hop-derived compounds for the first time. PMID:24175280

  16. Functional properties and antifungal activity of films based on gliadins containing cinnamaldehyde and natamycin.

    PubMed

    Balaguer, Mari Pau; Fajardo, Paula; Gartner, Hunter; Gomez-Estaca, Joaquin; Gavara, Rafael; Almenar, Eva; Hernandez-Munoz, Pilar

    2014-03-01

    Gliadin films cross-linked with cinnamaldehyde (1.5, 3, and 5%) and incorporated with natamycin (0.5%) were prepared by casting, and their antifungal activity, water resistance, and barrier properties were characterized. Incorporation of natamycin gave rise to films with greater water uptake, weight loss and diameter gain, and higher water vapor and oxygen permeabilities. These results may be associated to a looser packing of the protein chains as a consequence of the presence of natamycin. The different cross-linking degree of the matrices influenced the natamycin migration to the agar test media, increasing from 13.3 to 23.7 (μg/g of film) as the percentage of cinnamaldehyde was reduced from 5% to 1.5%. Antifungal activity of films was assayed against common food spoilage fungi (Penicillium species, Alternaria solani, Colletotrichum acutatum). The greatest effectiveness was obtained for films containing natamycin and treated with 5% of cinnamaldehyde. The level of cinnamaldehyde reached in the head-space of the test assay showed a diminishing trend as a function of time, which was in agreement with fungal growth and cinnamaldehyde metabolization. Developed active films were used in the packaging of cheese slices showing promising results for their application in active packaging against food spoilage. PMID:24412960

  17. A novel LKB1 isoform enhances AMPK metabolic activity and displays oncogenic properties.

    PubMed

    Dahmani, R; Just, P-A; Delay, A; Canal, F; Finzi, L; Prip-Buus, C; Lambert, M; Sujobert, P; Buchet-Poyau, K; Miller, E; Cavard, C; Marmier, S; Terris, B; Billaud, M; Perret, C

    2015-04-30

    The LKB1 tumor suppressor gene encodes a master kinase that coordinates the regulation of energetic metabolism and cell polarity. We now report the identification of a novel isoform of LKB1 (named ΔN-LKB1) that is generated through alternative transcription and internal initiation of translation of the LKB1 mRNA. The ΔN-LKB1 protein lacks the N-terminal region and a portion of the kinase domain. Although ΔN-LKB1 is catalytically inactive, it potentiates the stimulating effect of LKB1 on the AMP-activated protein kinase (AMPK) metabolic sensor through a direct interaction with the regulatory autoinhibitory domain of AMPK. In contrast, ΔN-LKB1 negatively interferes with the LKB1 polarizing activity. Finally, combining in vitro and in vivo approaches, we showed that ΔN-LKB1 has an intrinsic oncogenic property. ΔN-LKB1 is expressed solely in the lung cancer cell line, NCI-H460. Silencing of ΔN-LKB1 decreased the survival of NCI-H460 cells and inhibited their tumorigenicity when engrafted in nude mice. In conclusion, we have identified a novel LKB1 isoform that enhances the LKB1-controlled AMPK metabolic activity but inhibits LKB1-induced polarizing activity. Both the LKB1 tumor suppressor gene and the oncogene ΔN-LKB1 are expressed from the same locus and this may account for some of the paradoxical effects of LKB1 during tumorigenesis.

  18. Antiadherent and antibiofilm activity of Humulus lupulus L. derived products: new pharmacological properties.

    PubMed

    Rozalski, Marcin; Micota, Bartlomiej; Sadowska, Beata; Stochmal, Anna; Jedrejek, Dariusz; Wieckowska-Szakiel, Marzena; Rozalska, Barbara

    2013-01-01

    New antimicrobial properties of products derived from Humulus lupulus L. such as antiadherent and antibiofilm activities were evaluated. The growth of gram-positive but not gram-negative bacteria was inhibited to different extents by these compounds. An extract of hop cones containing 51% xanthohumol was slightly less active against S. aureus strains (MIC range 31.2-125.0  μg/mL) than pure xanthohumol (MIC range 15.6-62.5  μg/mL). The spent hop extract, free of xanthohumol, exhibited lower but still relevant activity (MIC range 1-2 mg/mL). There were positive coactions of hop cone, spent hop extracts, and xanthohumol with oxacillin against MSSA and with linezolid against MSSA and MRSA. Plant compounds in the culture medium at sub-MIC concentrations decreased the adhesion of Staphylococci to abiotic surfaces, which in turn caused inhibition of biofilm formation. The rate of mature biofilm eradication by these products was significant. The spent hop extract at MIC reduced biofilm viability by 42.8%, the hop cone extract by 74.8%, and pure xanthohumol by 86.5%. When the hop cone extract or xanthohumol concentration was increased, almost complete biofilm eradication was achieved (97-99%). This study reveals the potent antibiofilm activity of hop-derived compounds for the first time. PMID:24175280

  19. Properties of Binuclear Rhodium(II) Complexes and Their Antibacterial Activity

    PubMed Central

    Pruchnik, Florian P.; Bień, Małgorzata; Lachowicz, Tadeusz

    1996-01-01

    Binuclear rhodium(II) complexes [Rh2Cl2(μ-OOCR)2(N-N)2], [Rh2(μ-OOCR)2(N-N)2(H2O)2](RCOO)2 and [Rh2Cl2(μ-OOCCH3)(terpy)2](H3O)Cl2.9H2O (R = H, Me, Bun, ph, PhCHOH; N-N = 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (dmp) and 6,7-dimethyl-2,3- di(2-pyridyl)quinoxaline (dmpq); terpy 2,2′:6′,2′′-terpyridine) have been synthesized and their structure and properties have been studied by electronic, IR and 1H NMR spectroscopy. Antibacterial activity of these complexes against Staphylococcus aureus and Escherichia coli has been investigated. The most active antibacterial agents against S. aureus were [Rh2(OOCPh)2(phen)2(H2O)2]2+, [Rh2(OOCPh)2(dmpq)2(H2O)2]2+, [Rh2(OOCBu)2(phen)2(H2O)2]2+ and [Rh2-(OOCBu)2(bpy)2(H2O)2]2+ which were considerably more active than the appropriate nitrogen ligands. The complexes show rather low activity against E. coli. PMID:18475754

  20. Chemical properties and biological activity in soils of Mallorca following twenty years of treated wastewater irrigation.

    PubMed

    Adrover, Maria; Farrús, Edelweïss; Moyà, Gabriel; Vadell, Jaume

    2012-03-01

    On the Mediterranean island of Mallorca, the use of secondary-treated municipal wastewater in irrigation was introduced with the construction of the first wastewater treatment plants in the 1970s. In this study, the chemical properties and biological activity of 21 arable soils, irrigated for more than 20 years with secondary-treated wastewater, were tested in order to assess their quality. Soil quality was evaluated by measuring cation exchange capacity, pH, calcium carbonate equivalent, soil organic matter, total nitrogen, available phosphorus, water-soluble organic carbon, soil microbial biomass, soil basal respiration, and the activities of the enzymes dehydrogenase, β-glucosidase and alkaline phosphatase. No negative effects of the irrigation treatment were observed on the measured soil parameters. Indeed, soil water-soluble organic carbon, soil microbial biomass and β-glucosidase and alkaline phosphatase activities increased under treated wastewater irrigation. Biological activity of soils irrigated with treated wastewater was affected mainly by soil organic matter content. Although the typical crop management of alfalfa, and other forage crops associated with treated wastewater irrigation, may have contributed to the increase of these parameters, the results suggest that irrigation with treated wastewater is a strategy with many benefits to agricultural land management.

  1. Nonpeptidic Amphiphilic Xanthone Derivatives: Structure-Activity Relationship and Membrane-Targeting Properties.

    PubMed

    Koh, Jun-Jie; Zou, Hanxun; Lin, Shuimu; Lin, Huifen; Soh, Rui Ting; Lim, Fang Hui; Koh, Wee Luan; Li, Jianguo; Lakshminarayanan, Rajamani; Verma, Chandra; Tan, Donald T H; Cao, Derong; Beuerman, Roger W; Liu, Shouping

    2016-01-14

    We recently reported the bioinspired synthesis of a highly potent nonpeptidic xanthone, 2c (AM-0016), with potent antibacterial activity against MRSA. Herein, we report a thorough structure-activity relationship (SAR) analysis of a series of nonpeptidic amphiphilic xanthone derivatives in an attempt to identify more potent compounds with lower hemolytic activity and greater membrane selectivity. Forty-six amphiphilic xanthone derivatives were analyzed in this study and structurally classified into four groups based on spacer length, cationic moieties, lipophilic chains, and triarm functionalization. We evaluated and explored the effects of the structures on their membrane-targeting properties. The SAR analysis successfully identified 3a with potent MICs (1.56-3.125 μ/mL) and lower hemolytic activity (80.2 μg/mL for 3a versus 19.7 μg/mL for 2c). Compound 3a displayed a membrane selectivity of 25.7-50.4. Thus, 3a with improved HC50 value and promising selectivity could be used as a lead compound for further structural optimization for the treatment of MRSA infection. PMID:26681070

  2. Evaluation of nonlinear properties of epileptic activity using largest Lyapunov exponent

    NASA Astrophysics Data System (ADS)

    Medvedeva, Tatiana M.; Lüttjohann, Annika; van Luijtelaar, Gilles; Sysoev, Ilya V.

    2016-04-01

    Absence seizures are known to be highly non-linear large amplitude oscillations with a well pronounced main time scale. Whilst the appearance of the main frequency is usually considered as a transition from noisy complex dynamics of baseline EEG to more regular absence activity, the dynamical properties of this type of epileptiformic activity in genetic absence models was not studied precisely. Here, the estimation of the largest Lyapunov exponent from intracranial EEGs of 10 WAG/Rij rats (genetic model of absence epilepsy) was performed. Fragments of 10 seizures and 10 episodes of on-going EEG each of 4 s length were used for each animal, 3 cortical and 2 thalamic channels were analysed. The method adapted for short noisy data was implemented. The positive values of the largest Lyapunov exponent were found as for baseline as for spike wave discharges (SWDs), with values for SWDs being significantly less than for on-going activity. Current findings may indicate that SWD is a chaotic process with a well pronounced main timescale rather than a periodic regime. Also, the absence activity was shown to be less chaotic than the baseline one.

  3. Enantioselective synthesis of tatanans A-C and reinvestigation of their glucokinase-activating properties

    NASA Astrophysics Data System (ADS)

    Xiao, Qing; Jackson, Jeffrey J.; Basak, Ashok; Bowler, Joseph M.; Miller, Brian G.; Zakarian, Armen

    2013-05-01

    The tatanans are members of a novel class of complex sesquilignan natural products recently isolated from the rhizomes of Acorus tatarinowii Schott plants. Tatanans A, B and C have previously been reported to have potent glucokinase-activating properties that exceed the in vitro activity of known synthetic antidiabetic agents. Here, using a series of sequential [3,3]-sigmatropic rearrangements, we report the total synthesis of tatanan A in 13 steps and 13% overall yield. We also complete a concise enantioselective total synthesis of more complex, atropisomeric tatanans B and C via a distinct convergent strategy based on a palladium-catalysed diastereotopic aromatic group differentiation (12 steps, 4% and 8% overall yield, respectively). A plausible biosynthetic relationship between acyclic tatanan A and spirocyclic tatanans B and C is proposed and probed experimentally. With sufficient quantities of the natural products in hand, we undertake a detailed functional characterization of the biological activities of tatanans A-C. Contrary to previous reports, our assays utilizing pure recombinant human enzyme demonstrate that tatanans do not function as allosteric activators of glucokinase.

  4. Structural properties of cyanase. Denaturation, renaturation, and role of sulfhydryls and oligomeric structure in catalytic activity.

    PubMed

    Little, R M; Anderson, P M

    1987-07-25

    Cyanase is an inducible enzyme in Escherichia coli that catalyzes bicarbonate-dependent decomposition of cyanate to give ammonia and bicarbonate. The enzyme is composed of 8-10 identical subunits (Mr = 17,008). The objective of this study was to clarify some of the structural properties of cyanase for the purpose of understanding the relationship between oligomeric structure and catalytic activity. Circular dichroism studies showed that cyanase has a significant amount of alpha-helix and beta-sheet structure. The one sulfhydryl group per subunit does not react with 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) unless cyanase is denatured. Denaturation is apparently complete in 10 M urea or 6 M guanidine hydrochloride, but is significantly reduced in 10 M urea by the presence of azide (analog of cyanate) and is incomplete in 8 M urea. Denatured cyanase could be renatured and reactivated (greater than 85%) by removal of denaturants. Reactivation was greatly facilitated by the presence of certain anions, particularly bicarbonate, and by high ionic strength and protein concentration. The catalytic activity of renatured cyanase was associated only with oligomer. Cyanase that had been denatured in the presence of DTNB to give a cyanase-DTNB derivative could also be renatured at 26 degrees C to give active cyanase-DTNB oligomer. The active oligomeric form of the cyanase-DTNB derivative could be converted reversibly to inactive dimer by lowering the temperature to 4 degrees C or by reduction of the ionic strength and removal of monoanions. These results provide evidence that free sulfhydryl groups are not required for catalytic activity and that catalytic activity may be dependent upon oligomeric structure.

  5. Propolis induced antibacterial activity and other technical properties of cotton textiles.

    PubMed

    Sharaf, S; Higazy, A; Hebeish, A

    2013-08-01

    Propolis is a gum gathered by honey bees from various plants; the honey bees use propolis to seal holes in their honey combs, smooth out the internal wall and protect the entrance against intruders. It is composed of 50% resin (flavonoids and related phenolic acid), 30% wax, 10% essential oils, 5% pollen and 5% various organic components. As a natural mixture, propolis is widely used in medicine, cosmetics and food. So far no attempts have been yet made to make use of propolis in the realm of textile finishing. Current work presents the first systemic study targeted to build up a scientific basis for production of cotton textiles having antibacterial activity and other useful properties by making use of propolis as eco-friendly finish within the scope of green strategy. Propolis extract solution (70/30 ethanol/water) of 10% concentration was prepared as the stock. Different amounts of the latter were used along with a crosslinking agent and catalyst for treatment of cotton fabrics as per pad-dry-cure technique. Antibacterial activity of the so treated fabrics was obtained through monitoring the efficiency of the interaction of propolis with cotton cellulose. This interaction was expressed as inhibition zone diameter after the treated fabrics were exposed to (G+ve) and (G-ve) bacteria. Other properties include crease recovery, tensile strength and elongation at break. Factors affecting these properties such as type, nature and concentration of the crosslinking agent, concentration of propolis, and conditions of curing were investigated. In addition characterization of the propolis containing modified cotton fabrics including demonstration of the antibacterial activity, SEM, FTIR, durability to washing, UV protection and water repellency were performed. Based on results obtained, it is concluded that application of propolis along with glyoxal and Al2(SO4)3catalyst using pad-dry (3min/80°C), cure (5/140°C) bring about cotton textile with superior antibacterial

  6. Properties of a calcium-activated K(+) current on interneurons in the developing rat hippocampus.

    PubMed

    Aoki, T; Baraban, S C

    2000-06-01

    Calcium-activated potassium currents have an essential role in regulating excitability in a variety of neurons. Although it is well established that mature CA1 pyramidal neurons possess a Ca(2+)-activated K(+) conductance (I(K(Ca))) with early and late components, modulation by various endogenous neurotransmitters, and sensitivity to K(+) channel toxins, the properties of I(K(Ca)) on hippocampal interneurons (or immature CA1 pyramidal neurons) are relatively unknown. To address this problem, whole-cell voltage-clamp recordings were made from visually identified interneurons in stratum lacunosum-moleculare (L-M) and CA1 pyramidal cells in hippocampal slices from immature rats (P3-P25). A biphasic calcium-activated K(+) tail current was elicited following a brief depolarization from the holding potential (-50 mV). Analysis of the kinetic properties of I(K(Ca)) suggests that an early current component differs between these two cell types. An early I(K(Ca)) with a large peak current amplitude (200.8 +/- 13.2 pA, mean +/- SE), slow time constant of decay (70.9 +/- 3.3 ms), and relatively rapid time to peak (within 15 ms) was observed on L-M interneurons (n = 88), whereas an early I(K(Ca)) with a small peak current amplitude (112.5 +/- 7.3 pA), a fast time constant of decay (39.4 +/- 1.6 ms), and a slower time-to-peak (within 26 ms) was observed on CA1 pyramidal neurons (n = 85). Removal of extracellular calcium or addition of inorganic Ca(2+) channel blockers (cadmium, nickel, or cobalt) was used to demonstrate the calcium dependence of these currents. Addition of norepinephrine, carbachol, and a variety of channel toxins (apamin, iberiotoxin, verruculogen, paxilline, penitrem A, and charybdotoxin) were used to further distinguish between I(K(Ca)) on these two hippocampal cell types. Verruculogen (100 nM), carbachol (100 microM), apamin (100 nM), TEA (1 mM), and iberiotoxin (50 nM) significantly reduced early I(K(Ca)) on CA1 pyramidal neurons; early I(K(Ca)) on L

  7. Further Evolution of Multifunctional Niosomes Based on Pluronic Surfactant: Dual Active Targeting and Drug Combination Properties.

    PubMed

    Tavano, Lorena; Mauro, Loredana; Naimo, Giuseppina Daniela; Bruno, Leonardo; Picci, Nevio; Andò, Sebastiano; Muzzalupo, Rita

    2016-09-01

    The loading of chemotherapics into smart nanocarriers that simultaneously possess more than one useful property for specifically targeting a tumor site improves their therapeutic effectiveness, reducing their side effects. Hence, we proposed a combined approach for the treatment of human breast cancer (BC) consisting of the co-encapsulation of doxorubicin and curcumin or doxorubicin and quercetin into multifunctional niosomes, which results in prolonged blood circulation and an ability to spontaneously accumulate at the tumor site (passive target) and to recognize and bind the tumor cells through dual ligand-receptor interactions (active target). The drug-loaded vesicles showed high stability and good capability of loading doxorubicin and antioxidants alone or in combination. Their diameter was around 400 nm. The drugs released from the vesicles were found to be controlled and sustained for over 24 h, with a strong dependence on the co-presence of the loaded molecules. Transferrin and/or folic acid were conjugated on the external surface of the niosomes as ligands, considerably improving the cellular uptake into MCF-7 and MDA-MB-231 malignant cells when compared with the uptake of nonconjugated samples. In vitro evaluation of anticancer activity demonstrated the strong potential of niosomes loaded with a doxorubicin/curcumin combination as useful devices in breast tumor treatment. These features hold great promise for the development of multifunctional devices that combine several advantages such as biocompatibility, stealth properties, loading capability, and active targeting, moving toward the development of more specific and efficient carriers for personalized tumoral therapy. PMID:27504856

  8. Activation of human mast cells by retrocyclin and protegrin highlight their immunomodulatory and antimicrobial properties.

    PubMed

    Gupta, Kshitij; Kotian, Akhil; Subramanian, Hariharan; Daniell, Henry; Ali, Hydar

    2015-10-01

    Preclinical evaluation of Retrocyclins (RC-100, RC-101) and Protegrin-1 (PG-1) antimicrobial peptides (AMPs) is important because of their therapeutic potential against bacterial, fungal and viral infections. Human mast cells (HMCs) play important roles in host defense and wound healing but the abilities of retrocyclins and protegrin-1 to harness these functions have not been investigated. Here, we report that chemically synthesized RC-100 and PG-1 caused calcium mobilization and degranulation in HMCs but these responses were not blocked by an inhibitor of formyl peptide receptor-like 1 (FPRL1), a known receptor for AMPs. However, RC-100 and PG-1 induced degranulation in rat basophilic leukemia (RBL-2H3) cells stably expressing Mas related G protein coupled receptor X2 (MrgX2). Chemical synthesis of these AMPs is prohibitively expensive and post-synthesis modifications (cyclization, disulfide bonds, folding) are inadequate for optimal antimicrobial activity. Indeed, we found that synthetic RC-100, which caused mast cell degranulation via MrgX2, did not display any antimicrobial activity. Green-fluorescent protein (GFP)-tagged RC-101 (analog of RC-100) and GFP-tagged PG-1 purified from transgenic plant chloroplasts killed bacteria and induced mast cell degranulation. Furthermore, GFP-PG1 bound specifically to RBL-2H3 cells expressing MrgX2. These findings suggest that retrocyclins and protegrins activate HMCs independently of FPRL1 but via MrgX2. Harnessing this novel feature of AMPs to activate mast cell's host defense/wound healing properties in addition to their antimicrobial activities expands their clinical potential. Low cost production of AMPs in plants should facilitate their advancement to the clinic overcoming major hurdles in current production systems. PMID:26378047

  9. A novel stearic acid-modified hirudin peptidomimetic with improved pharmacokinetic properties and anticoagulant activity.

    PubMed

    Liu, Zhuguo; Yu, Zheng; Huang, Yuanyuan; Zhang, Yan; Han, Guozhu; Li, Xian; Dong, Mingxin; Yu, Shuo; Wang, Yu; Hu, Jie; Guo, Huiqin; Cheng, Yuanguo; Lv, Li; Dai, Qiuyun

    2015-01-01

    A novel hirudin isoform 3 mimetic peptide, named peptide S2, has been prepared by introduction of a stearic acid modification. Peptide S2 exhibited superior inhibitory activity to hirulog-1 (Bivariludin) and showed significantly higher anticoagulant potency in vivo. Peptide S2 elevated the thrombin time, prothrombin time and activated partial thromboplastin time of rat and human plasma more efficiently than hirulog-1 and the unmodified form of peptide S2 (peptide 1). Furthermore, peptide S2 inhibited arterial thrombosis and inferior vena cava in rat model 8 h after administration, and was 10-fold more potent than hirulog-1 300 min after administration of 0.1 μmol/kg peptide. The enhanced antithrombotic activity could be attributed to its long half-life (T1/2 = 212.2 ± 58.4 min), which was 13.1 and 14.7-fold longer than those of hirulog-1 (T1/2 = 15.1 ± 1.3 min) and peptide 1 (T1/2 = 13.5 ± 2.6 min), respectively. Further enzymatic degradation and binding assay with human serum albumin (HSA) demonstrated that the longer duration time should be originated from the slowing of trypsin or thrombin-mediated degradation, as well as its binding to HSA. The improved pharmacokinetic properties observed for peptide S2 has made it a promising therapeutic agent for the treatment of thrombi-related diseases.

  10. Liposomes loaded with a dirhenium compound and cisplatin: preparation, properties and improved in vivo anticancer activity.

    PubMed

    Li, Zhanyong; Shtemenko, Nataliia I; Yegorova, Dina Y; Babiy, Svetlana O; Brown, Andrew J; Yang, Tinglu; Shtemenko, Alexander V; Dunbar, Kim R

    2015-03-01

    Liposomes loaded with the rhenium compound (bis-dimethylsulfoxido-cis-tetrachlorodi-μ-pivalatodirhenium(III) (cis-Re2((CH3)3CCOO)2Cl4.2DMSO, I) and cisplatin in the molar ratio of 4:1 as well as those loaded only with I were synthesized and characterized by scanning electron microscopy, transmission electron microscopy, dynamic light scattering and electronic absorption spectroscopy. The relative stability of liposomes loaded with I is reflected by a minimal change in the electronic absorption spectra over a period of 8 days whereas the stability of those loaded with both drugs is lower, which we ascribe to the formation of new Re-Pt species inside the liposomes. Furthermore, the investigations of the co-encapsulation effects on the anticancer activity of the Re-Pt system were undertaken. Importantly, the co-encapsulated liposomes exhibit synergistic or additive anticancer activities in vivo, e.g. introduction of these liposomes into tumor-bearing rats demonstrated their antianemic, nephro- and hepato-protecting effects. These liposomes, which are active in cancer treatment, protect the dirhenium compounds from hydrolysis and preserve the biological properties of the Re-Pt hybrid. This study reveals the importance of combined therapy in nanotechnology and medicine. PMID:25203608

  11. Adhesive properties of the purified plasminogen activator Pla of Yersinia pestis.

    PubMed

    Lobo, Leandro Araujo

    2006-09-01

    The beta-barrel outer membrane protease Pla from Yersinia pestis is an important virulence factor in plague and enables initiation of the bubonic plague. Pla is a multifunctional protease whose expression also enhances bacterial adherence to extracellular matrix. It has remained uncertain whether the increase in cellular adhesiveness results from modification of the bacterial surface by Pla, or whether the Pla molecule is an adhesin. Pla was purified as a His6-fusion protein from Escherichia coli and reconstituted with lipopolysaccharide to an enzymatically active form. Purified His6-Pla was coated onto fluorescent micro-particles (FMPs) that expressed plasminogen activity. Pla-coated FMPs also bound to laminin and to reconstituted basement membrane (Matrigel) immobilized on permanox slides, whereas only poor activity was seen with lipopolysaccharide-coated FMPs or bovine serum albumin-coated FMPs. The results show that the Pla molecule has intrinsic adhesive properties and that purified transmembrane proteins coated onto FMPs can be used for functional assays. PMID:16923070

  12. Statistical properties of Hα flares in relation to sunspots and active regions in the cycle 23

    NASA Astrophysics Data System (ADS)

    Zharkov, S. I.; Zharkova, V. V.

    2011-02-01

    The statistical properties of Hα flare occurrences compared with those of sunspot and active region areas in the cycle 23. The flare numbers in the cycle 23 of all significances and locations were obtained from the Solar Geophysical Data (SGD) and the other data were taken from the automated Solar Feature Catalogues (SFC, http://solar.inf.brad.ac.uk). The average monthly flare occurrences during the whole cycle correlate closely with the total and cumulative areas of active regions and sunspots. The cumulative distribution of solar flare occurrences at different latitudes in the northern and southern hemispheres versus the time reveal a strong asymmetry with a domination of one or other hemispheres similar to the cumulative distributions of sunspots and active regions. Although the sunspot area asymmetry lags the flare occurrence asymmetry by about a few months at the ascending phase of the cycle and up to 12 months in the descending one. The latitudinal distribution of flare occurrences in the whole period reveals a well defined maximum at 18∘ in the northern and two maxima at 14∘ and 20∘ in the southern hemisphere. The longitudinal distributions of flare occurrence residuals of the running values and those averaged with a one year filter reveal a set of persistent longitudes in the opposite hemispheres lasting for about 1.0-1.5 years and changing quickly a few times over the cycle phases.

  13. Photocatalytic properties and selective antimicrobial activity of TiO2(Eu)/CuO nanocomposite

    NASA Astrophysics Data System (ADS)

    Michal, Robert; Dworniczek, Ewa; Caplovicova, Maria; Monfort, Olivier; Lianos, Panagiotis; Caplovic, Lubomir; Plesch, Gustav

    2016-05-01

    TiO2(Eu)/CuO nanocomposites were prepared by precipitation method. The anatase nanocrystallites with a size of 26 nm exhibited well crystallized and characteristical dipyramidal morphology and {1 0 1} and {0 0 1} faceting. Transmission electron microscopy photographs with atomic resolution showed that the Eu(III) dopants were bounded on surface of titania. In the composites, the CuO nanocrystals exhibiting a monoclinic tenorite structure with a size in the range from 2 to 5 nm were grafted to the surface of titania. The influence of copper(II) oxide led to distinct selectivity in the photocatalytic and antimicrobial properties of the investigated TiO2(Eu)/CuO nanocomposites. While the presence of CuO nanocrystals strongly increased the photocatalytic production of hydrogen by ethanol reforming, it decreased the activity in photoinduced total mineralization of phenol comparing with non-modified TiO2(Eu). In investigated TiO2(Eu)/CuO powders, the photoinduced antimicrobial activity against membranes of Enterococcus species was influenced by the selective binding of CuO to the surface of the microorganism leading to distinct selectivity in their action. The activity against Enterococcus faecalis was higher than against Enterococcus faecium.

  14. The physico-chemical properties and biostimulative activities of humic substances regenerated from lignite.

    PubMed

    David, Jan; Smejkalová, Daniela; Hudecová, Sárka; Zmeškal, Oldřich; von Wandruszka, Ray; Gregor, Tomáš; Kučerík, Jiří

    2014-01-01

    The positive effect of humic acids on the growth of plant roots is well known, however, the mechanisms and role of their physical structure in these processes have not been fully explained yet. In this work, South-Moravian lignite was oxidized by means of nitric acid and hydrogen peroxide to produce a set of regenerated humic acids. The elemental composition, solid state stability and solution characteristics were determined and correlated in vitro with their biological activity. A modified hydroponic method was applied to determine the effects of their potassium salts on Zea mays seedlings roots with respect to the plant weight, root length, root division, and starch and protein content. The relations between the determined parameters were evaluated through Principal Component Analysis and Pearson's correlation coefficients. The results indicated that the most important factor determining the biological activity of South-Moravian lignite potassium humates is related to the nature of self-assemblies, while the chemical composition had no direct connection with the root growth of Zea mays seedlings. It was demonstrated a controlled processing that provided humic substances with different chemical and physicochemical properties and variable biological activity.

  15. Attenuation Properties of Fontainebleau Sandstone During True-Triaxial Deformation using Active and Passive Ultrasonics

    NASA Astrophysics Data System (ADS)

    Goodfellow, S. D.; Tisato, N.; Ghofranitabari, M.; Nasseri, M. H. B.; Young, R. P.

    2015-11-01

    Active and passive ultrasonic methods were used to study the evolution of attenuation properties in a sample of Fontainebleau sandstone during true-triaxial deformation. A cubic sample of Fontainebleau sandstone (80 mm × 80 mm × 80 mm) was deformed under true-triaxial stresses until failure. From the stress state: σ _3 = 5 MPa and σ _1 = σ _2 = 35 MPa, σ _1 was increased at a constant displacement rate until the specimen failed. Acoustic emission (AE) activity was monitored by 18 piezoelectric sensors and bandpass filtered between 100 kHz and 1 MHz. A source location analysis was performed on discrete AE data harvested from the continuous record where 48,502 events were locatable inside the sample volume. AE sensors were sequentially pulsed during periodic P-wave surveys among 135 raypaths. Analytical solutions for Biot, squirt flow, viscous shear, and scattering attenuation were used to discuss to observed attenuation at various stages of the experiment. We concluded that initial attenuation anisotropy was stress induced and resulted from friction and squirt flow. Later attenuation of the high-frequency spectrum was attributed to scattering as a result of the formation of large macroscopic vertical fractures. Passive (AE) ultrasonic data produced similar information to that from active data but with enhanced temporal and spacial resolution.

  16. THE PROPERTIES OF QUASAR HOSTS AT THE PEAK OF THE QUASAR ACTIVITY

    SciTech Connect

    Kotilainen, Jari K.; Falomo, Renato; Decarli, Roberto; Treves, Aldo; Uslenghi, Michela; Scarpa, Riccardo E-mail: renato.falomo@oapd.inaf.i E-mail: aldo.treves@uninsubria.i E-mail: riccardo.scarpa@gtc.iac.e

    2009-10-01

    We present near-infrared imaging obtained with ESO VLT/ISAAC of a sample of 16 low luminosity radio-quiet quasars (RQQs) at the epoch around the peak of the quasar activity (2 < z < 3), aimed at investigating their host galaxies. For 11 quasars, we are able to detect the host galaxies and derive their properties, while for the other 5 quasars, upper limits to the host luminosity are estimated. The luminosities of the host galaxies of RQQs at high redshift are in the range of those of massive inactive elliptical galaxies. This work complements our previous systematic study of quasar hosts aimed to trace the cosmological luminosity evolution of the host galaxies up to z approx 2 and extends our pilot study of a few luminous quasars at z > 2. The luminosity trend with a cosmic epoch resembles that observed for massive inactive galaxies, suggesting a similar star formation history. In particular, both quasar host galaxies and massive inactive galaxies appear mostly assembled already at the peak age of the quasar activity. This result is of key importance for testing the models of joint formation and evolution of galaxies and their active nuclei.

  17. p-Chlorophenol adsorption on activated carbons with basic surface properties

    NASA Astrophysics Data System (ADS)

    Lorenc-Grabowska, Ewa; Gryglewicz, Grażyna; Machnikowski, Jacek

    2010-05-01

    The adsorption of p-chlorophenol (PCP) from aqueous solution on activated carbons (ACs) with basic surface properties has been studied. The ACs were prepared by two methods. The first method was based on the modification of a commercial CWZ AC by high temperature treatment in an atmosphere of ammonia, nitrogen and hydrogen. The second approach comprised the carbonization followed by activation of N-enriched polymers and coal tar pitch using CO 2 and steam as activation agent. The resultant ACs were characterized in terms of porous structure, elemental composition and surface chemistry (pH PZC, acid/base titration, XPS). The adsorption of PCP was carried out from an aqueous solution in static conditions. Equilibrium adsorption isotherm was of L2 type for polymer-based ACs, whereas L3-type isotherm was observed for CWZ ACs series. The Langmuir monolayer adsorption capacity was related to the porous structure and the amount of basic sites. A good correlation was found between the adsorption capacity and the volume of micropores with a width < 1.4 nm for polymer-based ACs. Higher nitrogen content, including that in basic form, did not correspond to the enhanced adsorption of PCP from aqueous solution. The competitive effect of water molecule adsorption on the PCP uptake is discussed.

  18. Islet neogenesis associated protein (ingap): structural and dynamical properties of its active pentadecapeptide.

    PubMed

    McCarthy, Andrés N; Mogilner, Inés G; Grigera, J Raúl; Borelli, M Inés; Del Zotto, Hector; Gagliardino, Juan José

    2009-02-01

    We have studied the structural and dynamical properties of the biologically active pentadecapeptide of the islet neogenesis associated protein (INGAP-PP) and of two other pentadecapeptides with the same amino acid composition but randomly scrambled primary sequences, using molecular dynamic simulations. Our data demonstrates that whilst the peptides with scrambled sequences show no definite prevalent structure in solution, INGAP-PP maintains a notably stable tertiary fold, namely, a conformer with a central beta-sheet and closed C-terminal. Such structure resembles the one corresponding to the amino acid sequence of human pancreatitis associated protein-1 (PAP-1), which presents 85% sequence homology with INGAP. These results could reasonably explain why the two scrambled sequences tested showed no biological activity, while INGAP-PP significantly increases beta-cells function and mass both in vitro and in vivo conditions. The capability of INGAP-PP to temporarily adopt other closely related conformations offers also a plausible explanation for the 50 fold experimental difference in potency between the active pentadecapeptide and the whole protein. They also suggest that the C-terminal region of INGAP-PP may plausibly be the locus for its interaction with the cell receptor. Consequently, the knowledge gathered through our data can help to obtain more potent INGAP-PP analogs, suitable for the prevention and treatment of diabetes.

  19. The physico-chemical properties and biostimulative activities of humic substances regenerated from lignite.

    PubMed

    David, Jan; Smejkalová, Daniela; Hudecová, Sárka; Zmeškal, Oldřich; von Wandruszka, Ray; Gregor, Tomáš; Kučerík, Jiří

    2014-01-01

    The positive effect of humic acids on the growth of plant roots is well known, however, the mechanisms and role of their physical structure in these processes have not been fully explained yet. In this work, South-Moravian lignite was oxidized by means of nitric acid and hydrogen peroxide to produce a set of regenerated humic acids. The elemental composition, solid state stability and solution characteristics were determined and correlated in vitro with their biological activity. A modified hydroponic method was applied to determine the effects of their potassium salts on Zea mays seedlings roots with respect to the plant weight, root length, root division, and starch and protein content. The relations between the determined parameters were evaluated through Principal Component Analysis and Pearson's correlation coefficients. The results indicated that the most important factor determining the biological activity of South-Moravian lignite potassium humates is related to the nature of self-assemblies, while the chemical composition had no direct connection with the root growth of Zea mays seedlings. It was demonstrated a controlled processing that provided humic substances with different chemical and physicochemical properties and variable biological activity. PMID:24790812

  20. Temperature dependence of photoluminescence properties in a thermally activated delayed fluorescence emitter

    SciTech Connect

    Niwa, Akitsugu; Kobayashi, Takashi Nagase, Takashi; Naito, Hiroyoshi; Goushi, Kenichi; Adachi, Chihaya

    2014-05-26

    Using steady-state and time-resolved photoluminescence (PL) spectroscopy, we have investigated the temperature dependence of PL properties of 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyano-benzene (4CzIPN), which have a small energy gap between its singlet and triplet excited states and thus exhibits efficient thermally activated delayed fluorescence [H. Uoyama et al., Nature 492, 235 (2012)]. Below around 100 K, PL quantum efficiency of 4CzIPN thin films is largely suppressed and strong photoexcitation intensity dependence appears. These features can be explained by using rate equations for the densities of singlet and triplet excited states considering a triplet-triplet annihilation process.

  1. Electronic structure and spectroscopic properties of anti-HIV active aminophenols

    NASA Astrophysics Data System (ADS)

    Bazyl', O. K.; Artyukhov, V. Ya.; Maier, G. V.; Tolstorozhev, G. B.; Raichenok, T. F.; Skornyakov, I. V.; Shadyro, O. I.; Sorokin, V. L.; Ksendzova, G. A.

    2012-02-01

    We have measured the absorption and fluorescence spectra and fluorescence quantum yields of sulphone-containing anti-HIV active o-aminophenol molecules in an inert solvent, hexane, and in a polar solvent, acetonitrile. We have studied IR Fourier-transform spectra and examined structural features of o-aminophenols with different substituents in solutions and crystals. Functional groups of molecules that are involved in the formation of hydrogen bonds have been revealed. Proton acceptor properties of o-aminophenol molecules have been theoretically evaluated using the method of molecular electrostatic potential. Using quantum chemistry methods, we have calculated and interpreted absorption and fluorescence spectra of o-aminophenols. Calculation data are compared with experimental results. We have determined the main channels and mechanisms of photophysical relaxation processes in o-aminophenols.

  2. Low-temperature mechanical and magnetic properties of the reduced activation martensitic steel

    NASA Astrophysics Data System (ADS)

    Ding, Hui-Li; Zhang, Tao; Gao, Rui; Wang, Xian-Ping; Fang, Qian-Feng; Liu, Chang-Song; Suo, Jin-Ping

    2015-09-01

    Mechanical and magnetic properties as well as their relationship in the reduced activation martensitic (RAM) steel were investigated in the temperature range from -90°C to 20°C. Charpy impact tests show that the ductile-to-brittle transition temperature (DBTT) of the RAM steel is about -60°C. Low-temperature tensile tests show that the yield strength, ultimate tensile strength and total elongation values increase as temperature decreases, indicating that the strength and plasticity below the DBTT are higher than those above the DBTT. The coercive field ( H C) in the scale of logarithm decreases linearly with the increasing temperature and the absolute value of the slope of ln H C versus temperature above the DBTT is obviously larger than that below the DBTT, also confirmed in the T91 steel. The results indicate that the non-destructive magnetic measurement is a promising candidate method for the DBTT detection of ferromagnetic steels.

  3. Thermal and Kinetic Properties of Motions in a Prominence Activation and Nearby Loop

    NASA Technical Reports Server (NTRS)

    Kucera, Therese; Landi, E.

    2005-01-01

    We perform a quantitative analysis of the thermal properties of a prominence activation and motions in a nearby loop. In order to make measurements of the quickly moving features seen in prominences in the UV we use the SOHO/SUMER spectrograph to take a time series of exposures from a single pointing position, providing a measurement of spectral line properties as a function of time and position along the slit. The lines observed cover a broad range of temperatures from 80,000 - 1.6 million K. These measurements are combined with TRACE movies in transition region and coronal temperature bands to obtain more complete information concerning prominence structure and motions. The resulting observations allow us to analyze the thermal and kinetic energy of the moving sources as functions of time. The loop and prominence are most apparent in lines formed at temperatures below 250,000 K. We find that in most cases the temperature distribution of plasma in a moving feature changes relatively little over time periods of about 20 minutes.

  4. Impact of active ingredients on the swelling properties of orally disintegrating tablets prepared by microwave treatment.

    PubMed

    Sano, Syusuke; Iwao, Yasunori; Kimura, Susumu; Noguchi, Shuji; Itai, Shigeru

    2014-07-01

    The impact of different active pharmaceutical ingredients (APIs) loading on the properties of orally disintegrating tablets (ODTs) prepared according to our previously reported microwave (MW) treatment process was evaluated using famotidine (FAM), acetaminophen (AAP), and ibuprofen (IBU). None of the APIs interrupted the tablet swelling during the MW treatment and the tablet hardness were improved by more than 20 N. MW treatment, however, led to a significant increase in the disintegration time of the ODTs containing IBU, but it had no impact on that of the ODTs containing FAM or AAP. This increased disintegration time of the ODTs containing IBU was attributed to the relatively low melting point of IBU (Tm=76 °C), with the IBU particles melting during the MW treatment to form agglomerates, which interrupted the penetration of water into the tablets and delayed their disintegration. The effects of the MW treatment on the chemical stability and dissolution properties of ODTs were also evaluated. The results revealed that MW treatment did not promote the degradations of FAM and AAP or delay their release from the ODTs, while dissolution of the ODTs containing IBU delayed by MW treatment. Based on these results, the MW method would be applicable to the preparation of ODTs containing APIs with melting points higher than 110 °C.

  5. Properties of lower-hybrid range wave activity at reconnection jet edge: 3D PIC simulations

    NASA Astrophysics Data System (ADS)

    Divin, Andrey; Khotyaintsev, Yuri; Vaivads, Andris; Andre, Mats; Lapenta, Giovanni; Markidis, Stefano

    2014-05-01

    Reconnection fronts are areas of intense currents and enhanced wave activity, since magnetic flux and plasma are piled up there when the accelerated flow encounters denser ambient current sheet. Observations and numerical simulations show that the fronts generate a variety of waves ranging from MHD frequencies up to lower hybrid frequency and above. In the present study we use 2D and 3D Particle-in-Cell (PIC) simulations to investigate the properties of the lower hybrid range waves developing at hot reconnected plasma - current sheet interface. Calculations are performed using implicit parallel code iPIC3D starting from conventional Harris current sheet. Initial evolution of the jet is simulated using 2D approach to save computational time, but 3D calculations are implemented at later stages in order to observe instability linear stage, saturation and transition to turbulence. Properties of the linear stage match closely theoretical predictions for the lower hybrid drift instability. During saturation, the mode produces intense electric fields (several Alfvén in electric fields normalized unit) that can provide an additional mechanism of electron heating at reconnection jet fronts.

  6. Effect of parboiling on phytochemical content, antioxidant activity and physicochemical properties of germinated red rice.

    PubMed

    Hu, Zhanqiang; Tang, Xiaozhi; Liu, Junfei; Zhu, Zhiwei; Shao, Yafang

    2017-01-01

    In order to improve functional properties and palatability of germinated red rice, this study investigated differences in phytochemicals and physicochemical properties of germinated red rice at 2, 5, 10, 15min of parboiling. Total free phenolic content and antioxidant activity of germinated red rice parboiled for 5 and 15min was higher than that of germinated red rice. Free p-coumaric acid increased from 0.20 to 0.67mg/100g with parboiling time increasing from 5 to 15min. Bound vanillic (0.17-0.27mg/100g) and p-coumaric acid (6.56-8.59mg/100g) had higher levels at 0, 2, or 5min. During 15min of parboiling, color difference (ΔE) increased from 0.58 to 9.09, heat enthalpy (ΔH) decreased from 4.69 to 1.94J/g, and internal structure of rice was destroyed. Overall, parboiling time of less than 5min was suitable to improve the quality of germinated red rice. PMID:27507477

  7. Anti-inflammatory properties of Septilin in lipopolysaccharide activated monocytes and macrophage.

    PubMed

    Varma, R Sandeep; Ashok, G; Vidyashankar, S; Patki, P; Nandakumar, K S

    2011-03-01

    In vivo studies have suggested the immunomodulatory properties of Septilin, an herbal preparation. This drug is being used against various types of inflammatory disorders. However, the mechanism of action of Septilin in the modulation of inflammation is not explored using suitable in vitro models. Hence, we decided to study the modulatory role of Septilin in lipopolysaccharide (LPS) mediated signaling in macrophage and monocyte cells. It was observed from the present study that by employing tumor necrosis factor α (TNF-α) bioassay and reverse transcription-polymerase chain reaction (RT-PCR), Septilin inhibited TNF-α production in LPS (1 μg/mL) stimulated RAW 264.7 cells (p < 0.05). 80% inhibition of TNF-α was observed even at 2.5% Septilin. Septilin at all the concentrations tested could also significantly block the LPS mediated nitric oxide (NO) production (p < 0.01) and expression of inducible NO synthase (iNOS) gene. LPS mediated interleukin 6 (IL-6) and IL-8 production was also blocked by Septilin at the concentrations tested. This herbal preparation could also inhibit cycloxygenase 2 (COX-2) activity and suppression of COX-2 and phosphodiesterase 4 B (PDE4B) mRNA expression in a concentration dependent manner. Taken together, these findings from the present in vitro study suggest the anti-inflammatory and immunomodulatory properties of Septilin.

  8. Temperature and time dependence of the electro-mechanical properties of flexible active fiber composites

    NASA Astrophysics Data System (ADS)

    Ben Atitallah, H.; Ounaies, Z.; Muliana, A.

    2016-04-01

    Active fiber composites (AFCs) are comprised of piezoelectric fibers embedded in a polymeric matrix. AFCs use interdigitated electrodes, which produce electric field lines parallel to the fiber direction, thus taking advantage of the larger d 33 piezoelectric coefficient. The polymer volume content of the AFCs is generally more than 50%; since polymers tend to have behaviors affected by their viscoelastic characteristics especially at elevated temperatures, it is necessary to understand the thermo-electro-mechanical behavior of AFCs at different loading rates. In this study, mechanical, electrical and electromechanical properties of AFCs were measured at different isothermal temperatures, namely 25 °C, 50 °C and 75 °C and at different loading rates. The measurements of all the properties of AFCs were done along the fiber direction. It was found that at higher temperatures, the modulus and tensile strength decreased for all strain rates and the strain at failure increased. The remnant polarization increased with decrease in frequency and increase in temperature; however, the coercive field decreased with temperature and was not affected by the frequency. Due to the viscoelastic behavior of the epoxy, the piezoelectric coefficient d 33 increased at higher temperature and lower frequency. It was also noted that this coefficient is dependent on the magnitude of the electric field.

  9. Effects of silver and gold catalytic activities on the structural and optical properties of silicon nanowires

    NASA Astrophysics Data System (ADS)

    Lajvardi, M.; Eshghi, H.; Izadifard, M.; Ghazi, M. E.; Goodarzi, A.

    2016-01-01

    The metal-assisted chemical etching of silicon in an aqueous solution of hydrofluoric acid and hydrogen peroxide is established for the fabrication of large area, uniform silicon nanowire (SiNW) arrays. In this study, silver (Ag) and gold (Au) are considered as catalysts and the effect of different catalysts with various thicknesses on the structural and optical properties of the fabricated SiNWs is investigated. The morphology of deposited catalysts on the silicon wafer is characterized by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). It is shown that the morphology of the fabricated silicon nanostructures remarkably depends upon the catalyst layer thickness, and the catalyst etching time directly affects the structural and optical properties of the synthesized SiNWs. FESEM images show a linear increment of the nanowire length versus time, whereas the etching rate for the Au-etched SiNWs was lower than the Ag-etched ones. Strong light scattering in SiNWs caused the total reflection to decrease in the range of visible light, and this decrement was higher for the Ag-etched SiNW sample, with a longer length than the Au-etched one. A broadband visible photoluminescence (PL) with different peak positions is observed for the Au- and Ag-etched samples. The synthesized optically active SiNWs can be considered as a promising candidate for a new generation of nano-scale opto-electronic devices.

  10. Modification of activated sludge properties caused by application of continuous and intermittent current.

    PubMed

    Ibeid, S; Elektorowicz, M; Oleszkiewicz, J A

    2013-02-01

    This study investigated the impact of direct current (DC) field on the activated sludge properties for potential improvement of the biological as well as membrane treatment processes. Three mixed-liquor suspended solids (MLSS) concentrations (5,000, 10,000 and 15,000 mg/l) were subjected to current densities (CD) ranging from 5 to 50 A/m² at five electrical exposure modes (time-ON/time-OFF). The results showed that CD between 15 and 35 A/m² increased the filterability of the sludge more than 200 times when compared with the untreated reference sludge. The average removals of protein, polysaccharides and organic colloids from the sludge supernatant at this range of CD were 43%, 73% and 91%, respectively, while the average reduction of the specific resistance to filtration (SRF) was 4.8 times higher. The changes of sludge properties depended on the current density, electrical exposure mode and the MLSS concentration. At CD of 25 A/m² and MLSS below 10,000 mg/l, shorter time-OFF was needed in each electrical cycle, while more time-OFF was needed at higher MLSS concentrations. It was concluded that proper application of the DC field could improve biomass in terms of its dewaterability and the removal of SMP, which are highly correlated to membrane fouling in the submerged membrane electro-bioreactor (SMEBR).

  11. Hancornia speciosa latex for biomedical applications: physical and chemical properties, biocompatibility assessment and angiogenic activity.

    PubMed

    Almeida, Luciane Madureira; Floriano, Juliana Ferreira; Ribeiro, Thuanne Pires; Magno, Lais Nogueira; da Mota, Lígia Souza Lima Silveira; Peixoto, Nei; Mrué, Fátima; Melo-Reis, Paulo; Lino Junior, Ruy de Souza; Graeff, Carlos Frederico de Oliveira; Gonçalves, Pablo José

    2014-09-01

    The latex obtained from Hancornia speciosa is used in folk medicine for treatment of several diseases, such as acne, warts, diabetes, gastritis and inflammation. In this work, we describe the biocompatibility assessment and angiogenic properties of H. speciosa latex and its potential application in medicine. The physical-chemical characterization was carried out following different methodologies (CHN elemental analyses; thermogravimetric analyses and Fourier transform infrared spectroscopy). The biocompatibility was evaluated through cytotoxicity and genotoxicity tests in fibroblast mouse cells and the angiogenic properties were evaluated using the chick chorioallantoic membrane (CAM) assay model. The physical-chemical results showed that the structure of Hancornia speciosa latex biomembrane is very similar to that of Hevea brasiliensis (commercially available product). Moreover, the cytotoxicity and genotoxicity assays showed that H. speciosa latex is biocompatible with life systems and can be a good biomaterial for medical applications. The CAM test showed the efficient ability of H. speciosa latex in neovascularization of tissues. The histological analysis was in accordance with the results obtained in the CAM assay. Our data indicate that the latex obtained from H. speciosa and eluted in water showed significant angiogenic activity without any cytotoxic or genotoxic effects on life systems. The same did not occur with H. speciosa latex stabilized with ammonia. Addition of ammonia does not have significant effects on the structure of biomembranes, but showed a smaller cell survival and a significant genotoxicity effect. This study contributes to the understanding of the potentialities of H. speciosa latex as a source of new phytomedicines.

  12. Evaluation of cytotoxicity, antimicrobial activity and physicochemical properties of a calcium aluminate-based endodontic material

    PubMed Central

    SILVA, Emmanuel João Nogueira Leal; HERRERA, Daniel Rodrigo; ROSA, Tiago Pereira; DUQUE, Thais Mageste; JACINTO, Rogério Castilho; GOMES, Brenda Paula Figueiredo de Almeida; ZAIA, Alexandre Augusto

    2014-01-01

    A calcium aluminate-based endodontic material, EndoBinder, has been developed in order to reduce MTA negative characteristics, preserving its biological properties and clinical applications. Objectives The aim of this study was to evaluate the cytotoxicity, antimicrobial activity, pH, solubility and water sorption of EndoBinder and to compare them with those of white MTA (WMTA). Material and Methods Cytotoxicity was assessed through a multiparametric analysis employing 3T3 cells. Antimicrobial activity against Enterococcus faecalis (ATCC 29212), Staphylococcus aureus. (ATCC 25923) and Candida albicans (ATCC 10556) was determined by the agar diffusion method. pH was measured at periods of 3, 24, 72 and 168 hours. Solubility and water sorption evaluation were performed following ISO requirements. Data were statistically analyzed by ANOVA and Tukey`s test with a significance level of 5%. Results EndoBinder and WMTA were non-cytotoxic in all tested periods and with the different cell viability parameters. There was no statistical differences between both materials (P>.05). All tested materials were inhibitory by direct contact against all microbial strains tested. EndoBinder and WMTA presented alkaline pH in all tested times with higher values of pH for WMTA (P<.05). Both materials showed values complying with the solubility minimum requirements. However, EndoBinder showed lower solubility than WMTA (P<.05). No statistical differences were observed regarding water sorption (P>.05). Conclusion Under these experimental conditions, we concluded that the calcium aluminate-based endodontic material EndoBinder demonstrated suitable biological and physicochemical properties, so it can be suggested as a material of choice in root resorption, perforations and root-end filling. PMID:24626250

  13. Comparative Pharmacokinetic Properties and Antitumor Activity of the Marine HDACi Largazole and Largazole Peptide Isostere

    PubMed Central

    Pilon, John L.; Clausen, Dane J.; Hansen, Ryan J.; Lunghofer, Paul J.; Charles, Brad; Rose, Barbara J.; Thamm, Douglas H.; Gustafson, Daniel L.; Bradner, James E.; Williams, Robert M.

    2015-01-01

    Purpose Largazole is a potent class I selective HDACi natural product isolated from the marine cyanobacteria Symploca sp. The purpose of this study was to test synthetic analogs of Largazole to identify potential scaffold structural modifications that would improve the drug-like properties of this clinically relevant natural product. Methods The impact of Largazole scaffold replacements on in vitro growth inhibition, cell cycle arrest, induction of apoptosis, pharmacokinetic properties, and in vivo activity using a xenograft model were investigated. Results In vitro studies in colon, lung, and pancreatic cancer cell lines showed that pyridyl substituted Largazole analogs had low nanomolar/high-picomolar activity on cell proliferation, and induced apoptosis and cell cycle arrest at concentrations equivalent to or lower than the parent compound Largazole. Using IV bolus delivery at 5mg/kg, two compartmental pharmacokinetic modeling on the peptide isostere analog of Largazole indicated improved pharmacokinetics including AUC, CL, and Vss. In the A549 non-small cell lung carcinoma xenograft model using a dosage of 5 mg/kg administered intraperitoneally every other day, Largazole, Largazole thiol, and Largazole peptide isostere demonstrated tumor growth inhibition (TGI%) of 32, 44, and 66 percent respectively. Moreover, the decreased tumor growth rate for Largazole peptide isostere was statistically significant compared to control (p=0.002) and superior to Largazole (p=0.006). Surprisingly tumor growth inhibition in this system and treatment regimen was not observed with the potent pyridyl-based analogs. Conclusions Our results establish that replacing the depsipepitde linkage in Largazole with an amide may impart pharmacokinetic advantage and that alternative prodrug forms of largazole are feasible. PMID:25616967

  14. EMG Activity of Masseter Muscles in the Elderly According to Rheological Properties of Solid Food

    PubMed Central

    Kang, Au Jin; Kang, Si Hyun; Seo, Kyung Mook; Park, Hyoung Su; Park, Ki-Hwan

    2016-01-01

    Objective To assess the impact of aging on masticatory muscle function according to changes in hardness of solid food. Methods Each of fifteen healthy elderly and young people were selected. Subjects were asked to consume cooked rice, which was processed using the guidelines of the Universal Design Foods concept for elderly people (Japan Care Food Conference 2012). The properties of each cooked rice were categorized as grade 1, 2, 3 and 4 (5×103, 2×104, 5×104, and 5×105 N/m2) respectively. Surface electromyography (sEMG) was used to measure masseter activity from food ingestion to swallowing of test foods. The raw data was normalized by the ratio of sEMG activity to maximal voluntary contraction and compared among subjects. The data was divided according to each sequence of mastication and then calculated within the parameters of EMG activities. Results Intraoral tongue pressure was significantly higher in the young than in the elderly (p<0.05). Maximal value of average amplitude of the sequence in whole mastication showed significant positive correlation with hardness of food in both young and elderly groups (p<0.05). In a comparisons between groups, the maximal value of average amplitude of the sequence in whole mastication and peak amplitude in whole mastication showed that mastication in the elderly requires a higher percentage of maximal muscle activity than in the young, even with soft foods (p<0.05). Conclusion sEMG data of the masseter can provide valuable information to aid in the selection of foods according to hardness for the elderly. The results also support the necessity of specialized food preparation or products for the elderly. PMID:27446781

  15. PHYSICAL PROPERTIES, STAR FORMATION, AND ACTIVE GALACTIC NUCLEUS ACTIVITY IN BALMER BREAK GALAXIES AT 0 < z < 1

    SciTech Connect

    Diaz Tello, J.; Donzelli, C.; Padilla, N.; Fujishiro, N.; Yoshikawa, T.; Hanami, H.; Hatsukade, B.

    2013-07-01

    We present a spectroscopic study with the derivation of the physical properties of 37 Balmer break galaxies, which have the necessary lines to locate them in star-forming-active galactic nuclei (AGNs) diagnostic diagrams. These galaxies span a redshift range from 0.045 to 0.93 and are somewhat less massive than similar samples of previous works. The studied sample has multiwavelength photometric data coverage from the ultraviolet to mid-infrared (MIR) Spitzer bands. We investigate the connection between star formation and AGN activity via optical, mass-excitation (MEx), and MIR diagnostic diagrams. Through optical diagrams, 31 (84%) star-forming galaxies, two (5%) composite galaxies, and three (8%) AGNs were classified, whereas from the MEx diagram only one galaxy was classified as AGN. A total of 19 galaxies have photometry available in all the IRAC/Spitzer bands. Of these, three AGN candidates were not classified as AGN in the optical diagrams, suggesting they are dusty/obscured AGNs, or that nuclear star formation has diluted their contributions. By fitting the spectral energy distribution of the galaxies, we derived the stellar masses, dust reddening E(B - V), ages, and UV star formation rates (SFRs). Furthermore, the relationship between SFR surface density ({Sigma}{sub SFR}) and stellar mass surface density per time unit ({Sigma}{sub M{sub */{tau}}}) as a function of redshift was investigated using the [O II] {lambda}3727, 3729, H{alpha} {lambda}6563 luminosities, which revealed that both quantities are larger for higher redshift galaxies. We also studied the SFR and specific SFR (SSFR) versus stellar mass and color relations, with the more massive galaxies having higher SFR values but lower SSFR values than less massive galaxies. These results are consistent with previous ones showing that, at a given mass, high-redshift galaxies have on average larger SFR and SSFR values than low-redshift galaxies. Finally, bluer galaxies have larger SSFR values than redder

  16. Staphylokinase has distinct modes of interaction with antimicrobial peptides, modulating its plasminogen-activation properties.

    PubMed

    Nguyen, Leonard T; Vogel, Hans J

    2016-01-01

    Staphylokinase (Sak) is a plasminogen activator protein that is secreted by many Staphylococcus aureus strains. Sak also offers protection by binding and inhibiting specific antimicrobial peptides (AMPs). Here, we evaluate Sak as a more general interaction partner for AMPs. Studies with melittin, mCRAMP, tritrpticin and bovine lactoferricin indicate that the truncation of the first ten residues of Sak (SakΔN10), which occurs in vivo and uncovers important residues in a bulge region, improves its affinity for AMPs. Melittin and mCRAMP have a lower affinity for SakΔN10, and in docking studies, they bind to the N-terminal segment and bulge region of SakΔN10. By comparison, lactoferricin and tritrpticin form moderately high affinity 1:1 complexes with SakΔN10 and their cationic residues form several electrostatic interactions with the protein's α-helix. Overall, our work identifies two distinct AMP binding surfaces on SakΔN10 whose occupation would lead to either inhibition or promotion of its plasminogen activating properties. PMID:27554435

  17. Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling

    PubMed Central

    Chaudhary, V.; Ramanujan, R.V.

    2016-01-01

    Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100−xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg−1. Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications. PMID:27725754

  18. Physical properties and biological activities of hesperetin and naringenin in complex with methylated β-cyclodextrin.

    PubMed

    Sangpheak, Waratchada; Kicuntod, Jintawee; Schuster, Roswitha; Rungrotmongkol, Thanyada; Wolschann, Peter; Kungwan, Nawee; Viernstein, Helmut; Mueller, Monika; Pongsawasdi, Piamsook

    2015-01-01

    The aim of this work is to improve physical properties and biological activities of the two flavanones hesperetin and naringenin by complexation with β-cyclodextrin (β-CD) and its methylated derivatives (2,6-di-O-methyl-β-cyclodextrin, DM-β-CD and randomly methylated-β-CD, RAMEB). The free energies of inclusion complexes between hesperetin with cyclodextrins (β-CD and DM-β-CD) were theoretically investigated by molecular dynamics simulation. The free energy values obtained suggested a more stable inclusion complex with DM-β-CD. The vdW force is the main guest-host interaction when hesperetin binds with CDs. The phase solubility diagram showed the formation of a soluble complex of AL type, with higher increase in solubility and stability when hesperetin and naringenin were complexed with RAMEB. Solid complexes were prepared by freeze-drying, and the data from differential scanning calorimetry (DSC) confirmed the formation of inclusion complexes. The data obtained by the dissolution method showed that complexation with RAMEB resulted in a better release of both flavanones to aqueous solution. The flavanones-β-CD/DM-β-CD complexes demonstrated a similar or a slight increase in anti-inflammatory activity and cytotoxicity towards three different cancer cell lines. The overall results suggested that solubilities and bioactivities of both flavanones were increased by complexation with methylated β-CDs.

  19. Derivatives of Ergot-alkaloids: Molecular structure, physical properties, and structure-activity relationships

    NASA Astrophysics Data System (ADS)

    Ivanova, Bojidarka B.; Spiteller, Michael

    2012-09-01

    A comprehensive screening of fifteen functionalized Ergot-alkaloids, containing bulk aliphatic cyclic substituents at D-ring of the ergoline molecular skeleton was performed, studying their structure-active relationships and model interactions with α2A-adreno-, serotonin (5HT2A) and dopamine D3 (D3A) receptors. The accounted high affinity to the receptors binding loops and unusual bonding situations, joined with the molecular flexibility of the substituents and the presence of proton accepting/donating functional groups in the studied alkaloids, may contribute to further understanding the mechanisms of biological activity in vivo and in predicting their therapeutic potential in central nervous system (CNS), including those related the Schizophrenia. Since the presented correlation between the molecular structure and properties, was based on the comprehensively theoretical computational and experimental physical study on the successfully isolated derivatives, through using routine synthetic pathways in a relatively high yields, marked these derivatives as 'treasure' for further experimental and theoretical studied in areas such as: (a) pharmacological and clinical testing; (b) molecular-drugs design of novel psychoactive substances; (c) development of the analytical protocols for determination of Ergot-alkaloids through a functionalization of the ergoline-skeleton, and more.

  20. Structure-property-composition relationships in doped zinc oxides: enhanced photocatalytic activity with rare earth dopants.

    PubMed

    Goodall, Josephine B M; Illsley, Derek; Lines, Robert; Makwana, Neel M; Darr, Jawwad A

    2015-02-01

    In this paper, we demonstrate the use of continuous hydrothermal flow synthesis (CHFS) technology to rapidly produce a library of 56 crystalline (doped) zinc oxide nanopowders and two undoped samples, each with different particle properties. Each sample was produced in series from the mixing of an aqueous stream of basic zinc nitrate (and dopant ion or modifier) solution with a flow of superheated water (at 450 °C and 24.1 MPa), whereupon a crystalline nanoparticle slurry was rapidly formed. Each composition was collected in series, cleaned, freeze-dried, and then characterized using analytical methods, including powder X-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller surface area measurement, X-ray photoelectron spectroscopy, and UV-vis spectrophotometry. Photocatalytic activity of the samples toward the decolorization of methylene blue dye was assessed, and the results revealed that transition metal dopants tended to reduce the photoactivity while rare earth ions, in general, increased the photocatalytic activity. In general, low dopant concentrations were more beneficial to having greater photodecolorization in all cases.

  1. Properties of alkali-solubilized collagen solution crosslinked by N-hydroxysuccinimide activated adipic acid

    NASA Astrophysics Data System (ADS)

    Chen, Yihui; Zhang, Min; Liu, Wentao; Li, Guoying

    2011-03-01

    The effect of N-hydroxysuccinimide activated adipic acid (NHS-AA) on the properties of alkali-solubilized collagen solutions was examined. The residual amino group content in crosslinked collagen, determined by trinitrobenzensulfonic acid (TNBS) assay, was decreased with increasing NHS-AA concentration. The results from differential scanning calorimeter (DSC) indicated that the maximum denaturation temperature ( T d) of crosslinked collagen solution was about 4.2°C higher than that of un-crosslinked collagen solution (36.6°C). Moreover, the values of storage modulus ( G'), loss modulus ( G″) and complex viscosity ( η*), obtained by means of dynamic frequency sweeps, were increased as NHS-AA concentration added up to 1.5 mM, and then decreased slightly when further increased NHS-AA concentration. Besides, for collagen solution crosslinked with 1.5 mM NHS-AA, dynamic denaturation temperature ( T dd) was about 1.1°C lower than T d (40.8°C), and the Arrhenius-type time-temperature superposition (TTS) principle was applied to yield the activation energy to be 474.4 kJmol-1.

  2. Magnetocaloric Properties of Fe-Ni-Cr Nanoparticles for Active Cooling

    NASA Astrophysics Data System (ADS)

    Chaudhary, V.; Ramanujan, R. V.

    2016-10-01

    Low cost, earth abundant, rare earth free magnetocaloric nanoparticles have attracted an enormous amount of attention for green, energy efficient, active near room temperature thermal management. Hence, we investigated the magnetocaloric properties of transition metal based (Fe70Ni30)100‑xCrx (x = 1, 3, 5, 6 and 7) nanoparticles. The influence of Cr additions on the Curie temperature (TC) was studied. Only 5% of Cr can reduce the TC from ~438 K to 258 K. These alloys exhibit broad entropy v/s temperature curves, which is useful to enhance relative cooling power (RCP). For a field change of 5 T, the RCP for (Fe70Ni30)99Cr1 nanoparticles was found to be 548 J-kg‑1. Tunable TCin broad range, good RCP, low cost, high corrosion resistance and earth abundance make these nanoparticles suitable for low-grade waste heat recovery as well as near room temperature active cooling applications.

  3. Anticancer activity and DNA-binding properties of novel cationic Pt(II) complexes.

    PubMed

    Jamshidi, Mehrnaz; Yousefi, Reza; Nabavizadeh, Seyed Masoud; Rashidi, Mehdi; Haghighi, Mohsen Golbon; Niazi, Ali; Moosavi-Movahedi, Ali-Akbar

    2014-05-01

    In this study, three structurally related cationic Pt complexes, [Pt(ppy)(dppe)]CF3CO2: C1, [Pt(bhq)(dppe)]CF3CO2: C2, and [Pt(bhq)(dppf)]CF3CO2: C3, in which ppy=deprotonated 2-phenylpyridine, bhq=deprotonated benzo[h]quinoline, dppe=bis(diphenylphosphino)ethane and dppf=1,1'-bis(diphenylphosphino)ferrocene, were used for the assessment of their anticancer activities against Jurkat and MCF-7 cancer cell lines. The Pt complexes (C1-C3) demonstrated significant level of anticancer properties, as measured using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. Moreover, the changes in nuclear morphology with Acridine Orange (AO) staining reveal that these complexes are capable to induce apoptosis, and only C1 stimulates activity of Caspase-3 in Jurkat cancer cells. To get a better insight into the nature of binding between these cationic Pt complexes and DNA, different spectroscopic techniques and gel electrophoresis were applied. On the basis of the results of UV/vis absorption spectroscopy, CD experiment and fluorescence quenching of ethidium bromide (EB)-DNA, the interaction between DNA and the Pt complexes is likely to occur through a mixed-binding mode. Overall, the present work suggests that a controlled modification could result in new potentially antitumor complexes which can survive the repair mechanism and induce facile apoptosis. PMID:24530367

  4. Material Properties and Antimicrobial Activity of Polyhydroxybutyrate (PHB) Films Incorporated with Vanillin.

    PubMed

    Xavier, Janifer Raj; Babusha, Sudalaimuthu Thangaraj; George, Johnsy; Ramana, Karna Venkata

    2015-07-01

    Polyhydroxybutyrate (PHB) was produced by Bacillus mycoides DFC 1, isolated from garden soil. Antimicrobial (AM) films of PHB were prepared by incorporating vanillin (4-hydroxy-3-methoxybenzaldehyde) from 10 to 200 μg/g of PHB. The films were assessed for antimicrobial activity against foodborne pathogens and spoilage bacteria comprising of Escherichia coli, Salmonella typhimurium, Shigella flexneri, and Staphylococcus aureus and fungi such as Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Aspergillus parasiticus, Aspergillus ochraceus, Penicillium viridicatum, and Penicillium clavigerum. The minimum concentration of vanillin required to exhibit antimicrobial activity was ≥80 μg/g PHB for bacteria and ≥50 μg/g PHB for fungi. The PHB films with and without vanillin were studied for mechanical and thermal properties such as tensile strength, Young's modulus, percentage elongation to break, melting temperature, and heat of fusion. The thermal stability of the films was studied using thermogravimetric analysis. The release kinetics of vanillin into food matrices was also checked using food stimulants. The study is intended to find applications for PHB films containing vanillin to enhance the shelf life of foods in the form of biodegradable wrapper.

  5. Brazilian Green Propolis: Anti-Inflammatory Property by an Immunomodulatory Activity

    PubMed Central

    Machado, Joleen Lopes; da Silva, Mayara Cristina Pinto; dos Reis, Aramys Silva; Costa, Graciomar Conceição; Arruda, Diêgo de Sousa; Rocha, Bruno Alves; Vaz, Mirela Mara de Oliveira Lima Leite; Paes, Antonio Marcus de Andrade; Guerra, Rosane Nassar Meireles; Berretta, Andresa Aparecida; do Nascimento, Flávia Raquel Fernandes

    2012-01-01

    The immunomodulatory and anti-inflammatory activities of green propolis extracts from Apis mellifera were investigated using acute and chronic inflammation models. Swiss mice were anesthetized and a cotton pellet granuloma was implanted in subcutaneous tissue. Then the mice were divided into six groups and received apyrogenic water or different propolis extracts by oral route (5 mg/kg). According to the treatment the groups were designated as E1A, E1B, E10, E11, and E12. The control group received apyrogenic water. The treatment was performed by six days when the mice were killed. The blood and the bronchoalveolar lavage (BAL) were collected to measure the leukocyte recruitment. In acute pulmonary inflammation, Balb/c mice received lipopolysaccharide (LPS) of Escherichia coli by intranasal route for three days. Concomitantly the mice received by oral route apyrogenic water (control) or E10 and E11 propolis extracts. BAL was performed to assess the inflammatory infiltrate and cytokine quantification. The results showed that the E11 extract has anti-inflammatory property in both models by the inhibition of proinflammatory cytokines and increase of anti-inflammatory cytokines suggesting an immunomodulatory activity. PMID:23320022

  6. Influence of microwave irradiation on boron concentrate activation with an emphasis on surface properties

    NASA Astrophysics Data System (ADS)

    Jiang, Tao; Zhang, Qiaoyi; Liu, Yajing; Xue, Xiangxin; Duan, Peining

    2016-11-01

    In this study, we employed microwave irradiation for activating boron concentrate, an abundant but low-grade boron mineral resource in China. The boron concentrate was pretreated by microwave irradiation based on TG-DTG-DSC analysis, and the influence of each parameter on processing efficiency was characterized using chemical analysis, XRD, SEM, FTIR and particle distribution analysis. Subsequently, the surface properties of boron concentrate and the mechanism of microwave irradiation was analyzed. Our results indicate that microwave irradiation decreased the processing temperature and shortened the roasting time by accelerating dehydroxylation and oxidation reactions in the boron concentrate, reducing the particle diameter and damaging the microstructure of the minerals, and it increased the B2O3 activity of boron from 64.68% to 86.73%, greater than the optimal conventional treatment. Compared with the simple thermal field, microwave roasting obviously increased ability of the boron concentrate to absorb OH- in the leachant and promoted boron leaching by expanding the contact area of the mineral exposed to leachant, boosting the amount of Mg2+ and Fe3+ on mineral surfaces, and increasing the hydrophilicity of the boron concentrate respectively. It enhanced the γSVLW and γSV- of boron concentrate from 29.15 mJ/m2 and 5.07 mJ/m2 to 37.07 mJ/m2 and 12.41 mJ/m2.

  7. Phenolic composition, physicochemical properties and antioxidant activity of interspecific hybrids of grapes growing in Poland.

    PubMed

    Samoticha, Justyna; Wojdyło, Aneta; Golis, Tomasz

    2017-01-15

    The study evaluated fruit quality parameters and chemical properties (soluble solids, pH, total acidity and total sugars content, phenolic compounds and antioxidant activity (ABTS, FRAP and ORAC methods)) of 30 grape cultivars of white, red and pink grape, as 28 interspecific hybrids and 2 Vitis vinifera L. popularly grown in Poland. Some of them were analyzed for the first time. A total of 49 polyphenolic compounds were identified by LC-PDA-QTOF/MS and quantified by UPLC-PDA-FL, as 26 anthocyanins, 9 flavonols and flavons, 7 phenolic acids, 6 flavan-3-ols, and 1 stilbene. The content of total polyphenols ranged from 1037.0 (Cascade cv.) to 5759.1mg/100gdm (Roesler cv.). However, the content of stilbene represented by trans resveratrol-3-glucoside was only 18.5-70.5mg/100gdm. Red grape cultivars like Roesler, Rothay and Swenson Red were characterized by the highest content of bioactive compounds and antioxidant activity (significantly more than 24, 12 and 53mmol TE/100gdm, by ABTS, FRAP and ORAC, respectively). Average total acidity and soluble solids for white (0.95g of tartaric acid in 100gfm and 17.1°Bx, respectively) and for red and pink (0.93g of tartaric acid in 100gfm and 17.4°Bx, respectively) cultivars were not significantly different (p>0.05). PMID:27542475

  8. Staphylokinase has distinct modes of interaction with antimicrobial peptides, modulating its plasminogen-activation properties

    PubMed Central

    Nguyen, Leonard T.; Vogel, Hans J.

    2016-01-01

    Staphylokinase (Sak) is a plasminogen activator protein that is secreted by many Staphylococcus aureus strains. Sak also offers protection by binding and inhibiting specific antimicrobial peptides (AMPs). Here, we evaluate Sak as a more general interaction partner for AMPs. Studies with melittin, mCRAMP, tritrpticin and bovine lactoferricin indicate that the truncation of the first ten residues of Sak (SakΔN10), which occurs in vivo and uncovers important residues in a bulge region, improves its affinity for AMPs. Melittin and mCRAMP have a lower affinity for SakΔN10, and in docking studies, they bind to the N-terminal segment and bulge region of SakΔN10. By comparison, lactoferricin and tritrpticin form moderately high affinity 1:1 complexes with SakΔN10 and their cationic residues form several electrostatic interactions with the protein’s α-helix. Overall, our work identifies two distinct AMP binding surfaces on SakΔN10 whose occupation would lead to either inhibition or promotion of its plasminogen activating properties. PMID:27554435

  9. Physical properties and biological activities of hesperetin and naringenin in complex with methylated β-cyclodextrin

    PubMed Central

    Sangpheak, Waratchada; Kicuntod, Jintawee; Schuster, Roswitha; Rungrotmongkol, Thanyada; Wolschann, Peter; Kungwan, Nawee; Viernstein, Helmut

    2015-01-01

    Summary The aim of this work is to improve physical properties and biological activities of the two flavanones hesperetin and naringenin by complexation with β-cyclodextrin (β-CD) and its methylated derivatives (2,6-di-O-methyl-β-cyclodextrin, DM-β-CD and randomly methylated-β-CD, RAMEB). The free energies of inclusion complexes between hesperetin with cyclodextrins (β-CD and DM-β-CD) were theoretically investigated by molecular dynamics simulation. The free energy values obtained suggested a more stable inclusion complex with DM-β-CD. The vdW force is the main guest–host interaction when hesperetin binds with CDs. The phase solubility diagram showed the formation of a soluble complex of AL type, with higher increase in solubility and stability when hesperetin and naringenin were complexed with RAMEB. Solid complexes were prepared by freeze-drying, and the data from differential scanning calorimetry (DSC) confirmed the formation of inclusion complexes. The data obtained by the dissolution method showed that complexation with RAMEB resulted in a better release of both flavanones to aqueous solution. The flavanones-β-CD/DM-β-CD complexes demonstrated a similar or a slight increase in anti-inflammatory activity and cytotoxicity towards three different cancer cell lines. The overall results suggested that solubilities and bioactivities of both flavanones were increased by complexation with methylated β-CDs. PMID:26877798

  10. Pharmacological Activities of Ruthenium Complexes Related to Their NO Scavenging Properties

    PubMed Central

    Castellarin, Anna; Zorzet, Sonia; Bergamo, Alberta; Sava, Gianni

    2016-01-01

    Angiogenesis is considered responsible for the growth of primary tumours and of their metastases. With the present study, the effects of three ruthenium compounds, potassiumchlorido (ethylendiamminotetraacetate)rutenate(III) (RuEDTA), sodium (bis-indazole)tetrachloro-ruthenate(III), Na[trans-RuCl4Ind2] (KP1339) and trans-imidazoledimethylsulphoxidetetrachloro-ruthenate (NAMI-A), are studied in vitro in models mimicking the angiogenic process. The ruthenium compounds reduced the production and the release of nitrosyls from either healthy macrophages and immortalized EA.hy926 endothelial cells. The effects of NAMI-A are qualitatively similar and sometimes quantitatively superior to those of RuEDTA and KP1339. NAMI-A reduces the production and release of nitric oxide (NO) by the EA.hy926 endothelial cells and correspondingly inhibits their invasive ability; it also strongly inhibits the angiogenesis in matrigel sponges implanted subcutaneously in healthy mice. Taken together, these data support the anti-angiogenic activity of the tested ruthenium compounds and they contribute to explain the selective activity of NAMI-A against solid tumour metastases, the tumour compartment on which angiogenesis is strongly involved. This anti-angiogenic effect may also contribute to the inhibition of the release of metastatic cells from the primary tumour. Investigations on the anti-angiogenic effects of NAMI-A at this level will increase knowledge of its pharmacological properties and it will give a further impulse to the development of this class of innovative metal-based drugs. PMID:27490542

  11. BiOCl nanosheets immobilized on electrospun polyacrylonitrile nanofibers with high photocatalytic activity and reusable property

    NASA Astrophysics Data System (ADS)

    Chou, Yuechen; Shao, Changlu; Li, Xinghua; Su, Chunyan; Xu, Hongchuan; Zhang, Mingyi; Zhang, Peng; Zhang, Xin; Liu, Yichun

    2013-11-01

    One-dimensional BiOCl/PAN composite nanofibers which are composed of bismuth oxychloride (BiOCl) nanosheets on electrospun polyacrylonitrile (PAN) nanofibers were fabricated by combining electrospinning technique and solvothermal method. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis diffuse reflectance, Fourier transform infrared spectrum, X-ray photoelectron spectroscopy, thermal gravimetric and differential thermal analysis, were used to characterize the as-fabricated BiOCl/PAN composite nanofibers. The results revealed that BiOCl nanosheets were successfully immobilized on electrospun PAN nanofibers. The contents of the BiOCl nanosheets were controlled by adjusting the precursor concentrations for the fabrication of BiOCl/PAN composite nanofibers during the solvothermal synthesis processes. It was found that some interactions might exist between BiOCl and PAN molecules of BiOCl/PAN composite nanofibers. The obtained BiOCl/PAN composite nanofibers exhibited high photocatalytic activity for degradation of rhodamine B under ultraviolet light irradiation. The trapping experiments confirmed that the main active species for photocatalysis was hydroxyl radicals, which was produced by both the oxidative pathway and reductive pathway. Notably, the BiOCl/PAN composite nanofibers photocatalysts not only had good reusable property because of their one-dimensional structure and flexibility but also retained high photocatalytic stabilities after several cycles due to the interaction between BiOCl and PAN molecules.

  12. Pharmacological Activities of Ruthenium Complexes Related to Their NO Scavenging Properties.

    PubMed

    Castellarin, Anna; Zorzet, Sonia; Bergamo, Alberta; Sava, Gianni

    2016-01-01

    Angiogenesis is considered responsible for the growth of primary tumours and of their metastases. With the present study, the effects of three ruthenium compounds, potassiumchlorido (ethylendiamminotetraacetate)rutenate(III) (RuEDTA), sodium (bis-indazole)tetrachloro-ruthenate(III), Na[trans-RuCl₄Ind₂] (KP1339) and trans-imidazoledimethylsulphoxidetetrachloro-ruthenate (NAMI-A), are studied in vitro in models mimicking the angiogenic process. The ruthenium compounds reduced the production and the release of nitrosyls from either healthy macrophages and immortalized EA.hy926 endothelial cells. The effects of NAMI-A are qualitatively similar and sometimes quantitatively superior to those of RuEDTA and KP1339. NAMI-A reduces the production and release of nitric oxide (NO) by the EA.hy926 endothelial cells and correspondingly inhibits their invasive ability; it also strongly inhibits the angiogenesis in matrigel sponges implanted subcutaneously in healthy mice. Taken together, these data support the anti-angiogenic activity of the tested ruthenium compounds and they contribute to explain the selective activity of NAMI-A against solid tumour metastases, the tumour compartment on which angiogenesis is strongly involved. This anti-angiogenic effect may also contribute to the inhibition of the release of metastatic cells from the primary tumour. Investigations on the anti-angiogenic effects of NAMI-A at this level will increase knowledge of its pharmacological properties and it will give a further impulse to the development of this class of innovative metal-based drugs. PMID:27490542

  13. Comparison of physicochemical properties and immunomodulatory activity of polysaccharides from fresh and dried litchi pulp.

    PubMed

    Huang, Fei; Zhang, Ruifen; Yi, Yang; Tang, Xiaojun; Zhang, Mingwei; Su, Dongxiao; Deng, Yuanyuan; Wei, Zhencheng

    2014-03-31

    Drying is commonly used for preservation and processing of litchi. However, its polysaccharide structure may be altered by the drying process, resulting in biological activity changes. Polysaccharides from fresh and dried litchi pulp (denoted as LPF and LPD, respectively) were isolated, investigated by GC-MS, GPC and UV/IR spectrum analysis and their antitumor and immunomodulatory activities were evaluated in vitro. LPD, the molecular weight of which was lower than that of LPF, contained more protein, uronic acid, arabinose, galactose and xylose. Compared with LPF, LPD exhibited a higher inhibitory effect on the proliferation of HepG2, Hela and A549 cells from 50-750 μg/mL. LPD was also a better stimulator of spleen lymphocyte proliferation, NK cells cytotoxicity and macrophage phagocytosis from 50-400 μg/mL. In summary, drying could change the physicochemical properties and enhance the bioactivity of polysaccharides from litchi pulp. This finding is supported by the fact that dried litchi pulps are used in Traditional Chinese Medicine.

  14. In Vitro Antioxidant versus Metal Ion Chelating Properties of Flavonoids: A Structure-Activity Investigation

    PubMed Central

    Cherrak, Sabri Ahmed; Mokhtari-Soulimane, Nassima; Berroukeche, Farid; Bensenane, Bachir; Cherbonnel, Angéline; Merzouk, Hafida; Elhabiri, Mourad

    2016-01-01

    Natural flavonoids such as quercetin, (+)catechin and rutin as well as four methoxylated derivatives of quercetin used as models were investigated to elucidate their impact on the oxidant and antioxidant status of human red blood cells (RBCs). The impact of these compounds against metal toxicity was studied as well as their antiradical activities with DPPH assay. Antihemolytic experiments were conducted on quercetin, (+)catechin and rutin with excess of Fe, Cu and Zn (400 μM), and the oxidant (malondialdehyde, carbonyl proteins) and antioxidant (reduced glutathione, catalase activity) markers were evaluated. The results showed that Fe and Zn have the highest prooxidant effect (37 and 33% of hemolysis, respectively). Quercetin, rutin and (+)catechin exhibited strong antioxidant properties toward Fe, but this effect was decreased with respect to Zn ions. However, the Cu showed a weak antioxidant effect at the highest flavonoid concentration (200 μM), while a prooxidant effect was observed at the lowest flavonoid concentration (100 μM). These results are in agreement with the physico-chemical and antiradical data which demonstrated that binding of the metal ions (for FeNTA: (+)Catechin, KLFeNTA = 1.6(1) × 106 M-1 > Rutin, KLFeNTA = 2.0(9) × 105 M-1 > Quercetin, KLFeNTA = 1.0(7) × 105 M-1 > Q35OH, KLFeNTA = 6.3(8.7) × 104 M-1 > Quercetin3’4’OH and Quercetin 3OH, KLFeNTA ~ 2 × 104 M-1) reflects the (anti)oxidant status of the RBCs. This study reveals that flavonoids have both prooxidant and antioxidant activity depending on the nature and concentration of the flavonoids and metal ions. PMID:27788249

  15. A novel stearic acid-modified hirudin peptidomimetic with improved pharmacokinetic properties and anticoagulant activity

    PubMed Central

    Liu, Zhuguo; Yu, Zheng; Huang, Yuanyuan; Zhang, Yan; Han, Guozhu; Li, Xian; Dong, Mingxin; Yu, Shuo; Wang, Yu; Hu, Jie; Guo, Huiqin; Cheng, Yuanguo; Lv, Li; Dai, Qiuyun

    2015-01-01

    A novel hirudin isoform 3 mimetic peptide, named peptide S2, has been prepared by introduction of a stearic acid modification. Peptide S2 exhibited superior inhibitory activity to hirulog-1 (Bivariludin) and showed significantly higher anticoagulant potency in vivo. Peptide S2 elevated the thrombin time, prothrombin time and activated partial thromboplastin time of rat and human plasma more efficiently than hirulog-1 and the unmodified form of peptide S2 (peptide 1). Furthermore, peptide S2 inhibited arterial thrombosis and inferior vena cava in rat model 8 h after administration, and was 10-fold more potent than hirulog-1 300 min after administration of 0.1 μmol/kg peptide. The enhanced antithrombotic activity could be attributed to its long half-life (T1/2 = 212.2 ± 58.4 min), which was 13.1 and 14.7-fold longer than those of hirulog-1 (T1/2 = 15.1 ± 1.3 min) and peptide 1 (T1/2 = 13.5 ± 2.6 min), respectively. Further enzymatic degradation and binding assay with human serum albumin (HSA) demonstrated that the longer duration time should be originated from the slowing of trypsin or thrombin–mediated degradation, as well as its binding to HSA. The improved pharmacokinetic properties observed for peptide S2 has made it a promising therapeutic agent for the treatment of thrombi-related diseases. PMID:26400022

  16. Properties of cyclic nucleotide-gated channels mediating olfactory transduction. Activation, selectivity, and blockage

    PubMed Central

    1992-01-01

    Cyclic nucleotide-gated channels (cng channels) in the sensory membrane of olfactory receptor cells, activated after the odorant-induced increase of cytosolic cAMP concentration, conduct the receptor current that elicits electrical excitation of the receptor neurons. We investigated properties of cng channels from frog and rat using inside- out and outside-out membrane patches excised from isolated olfactory receptor cells. Channels were activated by cAMP and cGMP with activation constants of 2.5-4.0 microM for cAMP and 1.0-1.8 for cGMP. Hill coefficients of dose-response curves were 1.4-1.8, indicating cooperativity of ligand binding. Selectivity for monovalent alkali cations and the Na/Li mole-fraction behavior identified the channel as a nonselective cation channel, having a cation-binding site of high field strength in the pore. Cytosolic pH effects suggest the presence of an additional titratable group which, when protonated, inhibits the cAMP-induced current with an apparent pK of 5.0-5.2. The pH effects were not voltage dependent. Several blockers of Ca2+ channels also blocked olfactory cng channels. Amiloride, D 600, and diltiazem inhibited the cAMP-induced current from the cytosolic side. Inhibition constants were voltage dependent with values of, respectively, 0.1, 0.3, and 1 mM at -60 mV, and 0.03, 0.02, and 0.2 mM at +60 mV. Our results suggest functional similarity between frog and rat cng channels, as well as marked differences to cng channels from photoreceptors and other tissues. PMID:1324972

  17. Effects of gamma irradiation on physicochemical properties, antioxidant and microbial activities of sour cherry juice

    NASA Astrophysics Data System (ADS)

    Arjeh, Edris; Barzegar, Mohsen; Ali Sahari, Mohammad

    2015-09-01

    Recently, due to the beneficial effects of bioactive compounds, demand for minimally processed fruits and fruit juices has increased rapidly in the world. In this study, sour cherry juice (SCJ) was exposed to gamma irradiation at 0.0, 0.5, 1.5, 3.0, 4.5, and 6.0 kGy and then stored at 4 °C for 60 days. Total soluble solids (TSS), total acidity (TA), color, total phenolic content (TPC), total monomeric anthocyanin content (TMC), antioxidant activity, organic acid profile, and microbial analysis were evaluated at regular intervals during the storage. Results indicated that irradiation did not have any significant effect on TSS, while level of TA increased significantly at the dose of 6 kGy (p<0.05). Furthermore, irradiation treatment and storage time led to a significant increase in L* and b* values and a decrease in a* values. Total monomeric anthocyanin content of the irradiated SCJ was lower than that of the non-irradiated one (24% at 3.0 kGy) and also changed toward a more negative direction during the storage (63% at 3.0 kGy for 60 days). There was a significant decrease in the antioxidant activity (DPPH radical scavenging and FRAP assay) in both irradiated and stored SCJs. After irradiation (0-6 kGy), the results showed that the concentration of malic and oxalic acid significantly increased; but, the concentration of ascorbic, citric, fumaric, and succinic acids significantly decreased. Gamma irradiation with doses of ≥3 kGy resulted in overall reduction in microbial loads. Based on the results obtained from the changes of physicochemical properties, antioxidant activity, and microbial analysis, irradiation of SCJ at doses of higher than 3.0 kGy is not recommended.

  18. Characterization of the active site properties of CYP4F12.

    PubMed

    Eksterowicz, John; Rock, Dan A; Rock, Brooke M; Wienkers, Larry C; Foti, Robert S

    2014-10-01

    Cytochrome P450 4F12 is a drug-metabolizing enzyme that is primarily expressed in the liver, kidney, colon, small intestine, and heart. The properties of CYP4F12 that may impart an increased catalytic selectivity (decreased promiscuity) were explored through in vitro metabolite elucidation, kinetic isotope effect experiments, and computational modeling of the CYP4F12 active site. By using astemizole as a probe substrate for CYP4F12 and CYP3A4, it was observed that although CYP4F12 favored astemizole O-demethylation as the primary route of metabolism, CYP3A4 was capable of metabolizing astemizole at multiple sites on the molecule. Deuteration of astemizole at the site of O-demethylation resulted in an isotope effect of 7.1 as well as an 8.3-fold decrease in the rate of clearance for astemizole by CYP4F12. Conversely, although an isotope effect of 3.8 was observed for the formation of the O-desmethyl metabolite when deuterated astemizole was metabolized by CYP3A4, there was no decrease in the clearance of astemizole. Development of a homology model of CYP4F12 based on the crystal structure of cytochrome P450 BM3 predicted an active site volume for CYP4F12 that was approximately 76% of the active site volume of CYP3A4. As predicted, multiple favorable binding orientations were available for astemizole docked into the active site of CYP3A4, but only a single binding orientation with the site of O-demethylation oriented toward the heme was identified for CYP4F12. Overall, it appears that although CYP4F12 may be capable of binding similar ligands to other cytochrome P450 enzymes such as CYP3A4, the ability to achieve catalytically favorable orientations may be inherently more difficult because of the increased steric constraints of the CYP4F12 active site. PMID:25074871

  19. Physicochemical properties influencing denitrification rate and microbial activity in denitrification bioreactors

    NASA Astrophysics Data System (ADS)

    Schmidt, C. A.

    2012-12-01

    The use of N-based fertilizer will need to increase to meet future demands, yet existing applications have been implicated as the main source of coastal eutrophication and hypoxic zones. Producing sufficient crops to feed a growing planet will require efficient production in combination with sustainable treatment solutions. The long-term success of denitrification bioreactors to effectively remove nitrate (NO¬3), indicates this technology is a feasible treatment option. Assessing and quantifying the media properties that affect NO¬3 removal rate and microbial activity can improve predictions on bioreactor performance. It was hypothesized that denitrification rates and microbial biomass would be correlated with total C, NO¬3 concentration, metrics of organic matter quality, media surface area and laboratory measures of potential denitrification rate. NO¬3 removal rates and microbial biomass were evaluated in mesocosms filled with different wood treatments and the unique influence of these predictor variables was determined using a multiple linear regression analysis. NO3 reduction rates were independent of NO¬3 concentration indicating zero order reaction kinetics. Temperature was strongly correlated with denitrification rate (r2=0.87; Q10=4.7), indicating the variability of bioreactor performance in differing climates. Fiber quality, and media surface area were strong (R>0.50), unique predictors of rates and microbial biomass, although C:N ratio and potential denitrification rate did not predict actual denitrification rate or microbial biomass. Utilizing a stepwise multiple linear regression, indicates that the denitrification rate can be effectively (r2=0.56;p<0.0001) predicted if the groundwater temperature, neutral detergent fiber and surface area alone are quantified. These results will assist with the widespread implementation of denitrification bioreactors to achieve significant N load reductions in large watersheds. The nitrate reduction rate as a

  20. Antithrombotic properties of SSR182289A, a new, orally active thrombin inhibitor.

    PubMed

    Lorrain, J; Millet, L; Lechaire, I; Lochot, S; Ferrari, P; Visconte, C; Sainte-Marie, M; Lunven, C; Berry, C N; Schaeffer, P; Herbert, J-M; O'Connor, S E

    2003-02-01

    N-[3-[[[(1S)-4-(5-Amino-2-pyridinyl)-1-[[4-difluoromethylene)-1-piperidinyl]carbonyl]butyl]amino]sulfonyl][1,1'-biphenyl]-2-yl]acetamide hydrochloride (SSR182289A) is a novel, potent, and selective thrombin inhibitor. We have examined the antithrombotic properties of SSR182289A administered by i.v. and p.o. routes in several different animal thrombosis models in comparison with reference antithrombotic agents. Oral administration of SSR182289A produced dose-related antithrombotic effects in the following models; rat venous thrombosis (ED(50) 0.9 mg/kg p.o.), rat silk thread arterio-venous (AV) shunt (ED(50) 3.8 mg/kg p.o.), rat thromboplastin-induced AV shunt (ED(50) 3.1 mg/kg p.o.), rat carotid artery thrombosis (ED(200) 5.9 mg/kg p.o.), and rabbit venous thrombosis (ED(50) 7.5 mg/kg p.o.). Administered as an i.v. bolus, SSR182289A showed antithrombotic activity in the above models with ED(50)/ED(200) values in the range of 0.2 to 1.9 mg/kg i.v. SSR182289A increased rat tail transection bleeding time at doses > or =10 mg/kg p.o. In the rat thromboplastin-induced AV shunt model, SSR182289A 10 mg/kg p.o. produced marked antithrombotic effects at 30, 60, 120, and 240 min after administration. Hence, SSR182289A demonstrates potent oral antithrombotic properties in animal venous, AV-shunt, and arterial thrombosis models.

  1. Synthesis of organometallic-based biologically active compounds: In vitro antibacterial, antifungal and cytotoxic properties of some sulfonamide incorporated ferrocences.

    PubMed

    Chohan, Zahid H

    2009-02-01

    Sulfonamides incorporated ferrocene (SIF) have been synthesized by the condensation reaction of sulfonamides (sulfanilamide, sulfathiazole or sulfamethaxazole) with 1,1'-diacetylferrocene. The synthesized compounds (SIF(1)-SIF(4)) have been characterized by their physical, spectral and analytical properties and have been screened for their in vitro antibacterial properties against pathogenic bacterial strains e.g., Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis Staphylococcus aureus and Salmonella typhi and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata using Agar-well diffusion method. Most of the compounds showed good antibacterial activity whereas, all the compounds exhibited significant antifungal activity. Brine shrimp bioassay was also carried out for in vitro cytotoxic properties against Artemia salina. PMID:18608785

  2. Photospheric Magnetic Field Properties of Flaring versus Flare-quiet Active Regions. II. Discriminant Analysis

    NASA Astrophysics Data System (ADS)

    Leka, K. D.; Barnes, G.

    2003-10-01

    We apply statistical tests based on discriminant analysis to the wide range of photospheric magnetic parameters described in a companion paper by Leka & Barnes, with the goal of identifying those properties that are important for the production of energetic events such as solar flares. The photospheric vector magnetic field data from the University of Hawai'i Imaging Vector Magnetograph are well sampled both temporally and spatially, and we include here data covering 24 flare-event and flare-quiet epochs taken from seven active regions. The mean value and rate of change of each magnetic parameter are treated as separate variables, thus evaluating both the parameter's state and its evolution, to determine which properties are associated with flaring. Considering single variables first, Hotelling's T2-tests show small statistical differences between flare-producing and flare-quiet epochs. Even pairs of variables considered simultaneously, which do show a statistical difference for a number of properties, have high error rates, implying a large degree of overlap of the samples. To better distinguish between flare-producing and flare-quiet populations, larger numbers of variables are simultaneously considered; lower error rates result, but no unique combination of variables is clearly the best discriminator. The sample size is too small to directly compare the predictive power of large numbers of variables simultaneously. Instead, we rank all possible four-variable permutations based on Hotelling's T2-test and look for the most frequently appearing variables in the best permutations, with the interpretation that they are most likely to be associated with flaring. These variables include an increasing kurtosis of the twist parameter and a larger standard deviation of the twist parameter, but a smaller standard deviation of the distribution of the horizontal shear angle and a horizontal field that has a smaller standard deviation but a larger kurtosis. To support the

  3. A Systematic Review of the Clinimetric Properties of Habitual Physical Activity Measures in Young Children with a Motor Disability

    PubMed Central

    Oftedal, Stina; Bell, Kristie L.; Mitchell, Louise E.; Davies, Peter S. W.; Ware, Robert S.; Boyd, Roslyn N.

    2012-01-01

    Aim. To identify and systematically review the clinimetric properties of habitual physical activity (HPA) measures in young children with a motor disability. Method. Five databases were searched for measures of HPA including: children aged <6.0 years with a neuromuscular disorder, physical activity defined as “bodily movement produced by skeletal muscles causing caloric expenditure”, reported HPA as duration, frequency, intensity, mode or energy expenditure, and evaluated clinimetric properties. The quality of papers was assessed using the COSMIN-checklist. A targeted search of identified measures found additional studies of typically developing young children (TDC). Results. Seven papers assessing four activity monitors met inclusion criteria. Four studies were of good methodological quality. The Minimod had good ability to measure continuous walking but the demonstrated poor ability to measure steps during free-living activities. The Intelligent Device for Energy Expenditure and Activity and Ambulatory Monitoring Pod showed poor ability to measure activity during both continuous walking and free-living activities. The StepWatch showed good ability to measure steps during continuous walking in TDC. Interpretation. Studies assessing the clinimetric properties of measures of HPA in this population are urgently needed to allow assessment of the relationship between HPA and health outcomes in this group. PMID:22927865

  4. Sustainable development of tyre char-based activated carbons with different textural properties for value-added applications.

    PubMed

    Hadi, Pejman; Yeung, Kit Ying; Guo, Jiaxin; Wang, Huaimin; McKay, Gordon

    2016-04-01

    This paper aims at the sustainable development of activated carbons for value-added applications from the waste tyre pyrolysis product, tyre char, in order to make pyrolysis economically favorable. Two activation process parameters, activation temperature (900, 925, 950 and 975 °C) and residence time (2, 4 and 6 h) with steam as the activating agent have been investigated. The textural properties of the produced tyre char activated carbons have been characterized by nitrogen adsorption-desorption experiments at -196 °C. The activation process has resulted in the production of mesoporous activated carbons confirmed by the existence of hysteresis loops in the N2 adsorption-desorption curves and the pore size distribution curves obtained from BJH method. The BET surface area, total pore volume and mesopore volume of the activated carbons from tyre char have been improved to 732 m(2)/g, 0.91 cm(3)/g and 0.89 cm(3)/g, respectively. It has been observed that the BET surface area, mesopore volume and total pore volume increased linearly with burnoff during activation in the range of experimental parameters studied. Thus, yield-normalized surface area, defined as the surface area of the activated carbon per gram of the precursor, has been introduced to optimize the activation conditions. Accordingly, the optimized activation conditions have been demonstrated as an activation temperature of 975 °C and an activation time of 4 h.

  5. Sustainable development of tyre char-based activated carbons with different textural properties for value-added applications.

    PubMed

    Hadi, Pejman; Yeung, Kit Ying; Guo, Jiaxin; Wang, Huaimin; McKay, Gordon

    2016-04-01

    This paper aims at the sustainable development of activated carbons for value-added applications from the waste tyre pyrolysis product, tyre char, in order to make pyrolysis economically favorable. Two activation process parameters, activation temperature (900, 925, 950 and 975 °C) and residence time (2, 4 and 6 h) with steam as the activating agent have been investigated. The textural properties of the produced tyre char activated carbons have been characterized by nitrogen adsorption-desorption experiments at -196 °C. The activation process has resulted in the production of mesoporous activated carbons confirmed by the existence of hysteresis loops in the N2 adsorption-desorption curves and the pore size distribution curves obtained from BJH method. The BET surface area, total pore volume and mesopore volume of the activated carbons from tyre char have been improved to 732 m(2)/g, 0.91 cm(3)/g and 0.89 cm(3)/g, respectively. It has been observed that the BET surface area, mesopore volume and total pore volume increased linearly with burnoff during activation in the range of experimental parameters studied. Thus, yield-normalized surface area, defined as the surface area of the activated carbon per gram of the precursor, has been introduced to optimize the activation conditions. Accordingly, the optimized activation conditions have been demonstrated as an activation temperature of 975 °C and an activation time of 4 h. PMID:26775155

  6. The dependence of X-ray AGN activity on host galaxy properties and environment

    NASA Astrophysics Data System (ADS)

    Tasse, C.; Röttgering, H.; Best, P. N.

    2011-01-01

    There is mounting evidence that active galactic nuclei (AGN) selected through optical emission lines or radio luminosities comprise two distinct AGN populations, whose activity is triggered by different processes. In two previous papers, we studied the host galaxies and environment of radio-loud AGN. In this third paper we study the properties of a sample of Type-2 AGN that were selected on the basis of their [2-10] keV X-ray luminosity. We find that the X-ray luminosity function is in good agreement with previous studies and that the fraction of galaxies hosting an X-ray AGN is a strong function of the stellar mass of the host galaxy. The shape of this fraction-mass relation is similar to the fraction of galaxies that are emission-line AGN, while it differs significantly from the relation observed for radio-selected AGN. The AGN in our sample tend to be located in underdense environments where galaxy mergers and interactions are likely to occur. For all host galaxy masses, the Type-2 AGN display a strong infrared excess at short (~3.5 μm) wavelengths, suggesting the presence of hot dust possibly associated with a hot dusty torus. These results add weight to the belief that the X-ray selection criteria identifies a population of AGN similar to the emission-line selected population but distinct from the radio population at high masses. Appendix A is only available in electronic form at http://www.aanda.org

  7. Identification and molecular docking analysis of active ingredients with medicinal properties from edible Baccaurea sapida.

    PubMed

    Mann, Sonia; Sharma, Ankita; Biswas, Sagarika; Gupta, Rajinder K

    2015-01-01

    Underutilized plant species has started changing the conception of plants by expanding the use well beyond from foods and fibers to rich source of medicinally important secondary metabolites. Bioactive compounds from natural sources are gaining importance as potential drug candidates towards many inflammatory conditions like Rheumatoid Arthritis (RA). The focus of the present study has been centred to reveal the anti-inflammatory potential of an underutilized fruits of B. sapida. Further efforts towards its medicinal significance may provide relieve from symptoms of RA by reducing the side effects that are observed in available medications. Total 10 compounds in fruit crude methanol extract were identified and quantified by LC-MS/MS analysis followed by the agar well diffusion method for their anti microbial activity. Among all studied micro organism S. aureus was found to surmount the inflammation in RA through domain B of surface protein A (Staphylococcal surface protein A). Identified compounds (having anti-inflammatory properties) were scrutinized for their toxicity and quantitative structure-activity relationship (QSAR) using lazer toxicity and Molinspiration servers respectively. Further, docking studies have been carried out between domain B and studied compounds using AutoDock. Out of 6 anti-inflammtory compounds, quercetin has been identified as the most potent compound in reference to its inhibitory constant (47.01) and binding energy (-5.90 kcal/mol) to bacterial protein. Our data suggest that methanol extract of B. sapida fruit posses medicinally significant anti-inflammatory compounds and thus justifies the use of this fruit as folklore medicine for preventing inflammation related diseases. PMID:26527853

  8. Oligomerization of Mannan-binding Lectin Dictates Binding Properties and Complement Activation.

    PubMed

    Kjaer, T R; Jensen, L; Hansen, A; Dani, R; Jensenius, J C; Dobó, J; Gál, P; Thiel, S

    2016-07-01

    The complement system is a part of the innate immune system and is involved in recognition and clearance of pathogens and altered-self structures. The lectin pathway of the complement system is initiated when soluble pattern recognition molecules (PRMs) with collagen-like regions bind to foreign or altered self-surfaces. Associated with the collagen-like stems of these PRMs are three mannan-binding lectin (MBL)-associated serine proteases (MASPs) and two MBL-associated proteins (MAps). The most studied of the PRMs, MBL, is present in serum mainly as trimeric and tetrameric oligomers of the structural subunit. We hypothesized that oligomerization of MBL may influence both the potential to bind to micro organisms and the interaction with the MASPs and MAps, thus influencing the ability to initiate complement activation. When testing binding at 37 °C, we found higher binding of tetrameric MBL to Staphylococcus aureus (S. aureus) than trimeric and dimeric MBL. In serum, we found that tetrameric MBL was the main oligomeric form present in complexes with the MASPs and MAp44. Such preference was confirmed using purified forms of recombinant MBL (rMBL) oligomers, where tetrameric rMBL interacted stronger with all of the MASPs and MAp44, compared to trimeric MBL. As a direct consequence of the weaker interaction with the MASPs, we found that trimeric rMBL was inferior to tetrameric rMBL in activating the complement system. Our data suggest that the oligomeric state of MBL is crucial both for the binding properties and the effector function of MBL.

  9. Elucidating the structure-activity relationships of the vasorelaxation and antioxidation properties of thionicotinic acid derivatives.

    PubMed

    Prachayasittikul, Supaluk; Wongsawatkul, Orapin; Worachartcheewan, Apilak; Nantasenamat, Chanin; Ruchirawat, Somsak; Prachayasittikul, Virapong

    2010-01-06

    Nicotinic acid, known as vitamin B(3), is an effective lipid lowering drug and intense cutaneous vasodilator. This study reports the effect of 2-(1-adamantylthio)nicotinic acid (6) and its amide 7 and nitrile analog 8 on phenylephrine-induced contraction of rat thoracic aorta as well as antioxidative activity. It was found that the tested thionicotinic acid analogs 6-8 exerted maximal vasorelaxation in a dose-dependent manner, but their effects were less than acetylcholine (ACh)-induced nitric oxide (NO) vasorelaxation. The vasorelaxations were reduced, apparently, in both N(G)-nitro-L-arginine methyl ester (L-NAME) and indomethacin (INDO). Synergistic effects were observed in the presence of L-NAME plus INDO, leading to loss of vasorelaxation of both the ACh and the tested nicotinic acids. Complete loss of the vasorelaxation was noted under removal of endothelial cells. This infers that the vasorelaxations are mediated partially by endothelium-induced NO and prostacyclin. The thionicotinic acid analogs all exhibited antioxidant properties in both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide dismutase (SOD) assays. Significantly, the thionicotinic acid 6 is the most potent vasorelaxant with ED(50) of 21.3 nM and is the most potent antioxidant (as discerned from DPPH assay). Molecular modeling was also used to provide mechanistic insights into the vasorelaxant and antioxidative activities. The findings reveal that the thionicotinic acid analogs are a novel class of vasorelaxant and antioxidant compounds which have potential to be further developed as promising therapeutics.

  10. Properties of human motor units after prolonged activity at a constant firing rate.

    PubMed

    Johnson, K V B; Edwards, S C; Van Tongeren, C; Bawa, P

    2004-02-01

    The primary purpose of this study was to examine if there are changes in the intrinsic properties of spinal motoneurons after prolonged submaximal contractions. To do this, we assessed whether or not the synaptic drive to motoneurons needs to increase in order to maintain a constant firing rate of a motor unit. Recruitment of new units and an increase in total electromyographic (EMG) activity of the muscle of interest were taken as estimates of an increase in synaptic drive. Subjects were asked to maintain a constant firing rate of a clearly identifiable (targeted) motor unit from the first dorsal interosseous muscle for approximately 10 min, while surface EMG and force were recorded simultaneously. For the 60 units studied, the duration of the constant-firing-rate period ranged from 73 to 1,140 s (448 +/- 227 s; mean +/- SD). There was a significant increase ( t-test, p<0.001) in the magnitude of mean surface EMG, and DC force while the targeted motoneuron maintained a constant rate suggesting an increase in the net excitatory input to the motoneuron pool. Changes occurring simultaneously in other parameters, namely, variability in interspike interval, magnitude of force fluctuations, the duration of motor unit action potentials, and the median power frequency of surface EMG were also computed. The firing rates of 16 concurrently firing motoneurons, not controlled by the subject, remained constant. The key finding of this study is that after prolonged activity, a motoneuron requires a stronger excitatory input to maintain its firing rate. Additional results are indicative of significant changes in the characteristics of the synaptic inputs, changes at the neuromuscular junction (both pre- and postsynaptic regions) and the sarcolemma.

  11. "RED" matters when naming "CAR": The cascading activation of nontarget properties.

    PubMed

    Roux, Sébastien; Bonin, Patrick

    2016-03-01

    Seven experiments tested, whether when naming a colored object (e.g., CAR), its color (e.g., red) is phonologically encoded. In the first experiment, adults had to say aloud the names of colored line drawings of objects that were each displayed among 3 black-and-white line drawings (Experiment 1a) or that were presented alone (Experiment 1b). Naming times were shorter in Experiment 1a, but not in Experiment 1b, when both the color and object names were phonologically related (e.g., blue ball). In Experiment 2a, adults had to name objects having diagnostic colors (e.g., banana, tomato) while hearing distractor words. Compared with unrelated distractors, object naming times were longer when the distractors were phonologically related to the names of the colors, indicating that the names of the colors were activated. In Experiment 2b, this inhibitory effect did not surface when the same pictures were displayed in black and white, indicating that it originates from the perceptual level. In Experiment 3a, we used the same paradigm as in Experiment 2 (a and b) with objects having "plausible," but nondiagnostic, colors (e.g., red CAR). The inhibitory effect of color-related distractors turned out to be reliable but it vanished when regular colored-line drawings were used (Experiment 3b) and when colors and objects were spatially segregated (Experiment 3c). Taken together, the findings strongly suggest that under certain circumstances, an object's properties are phonologically activated during object naming. These findings are accounted for in terms of the general attentional view of cascading of Oppermann, Jescheniak, Schriefers, and Görges (2010). PMID:26389629

  12. Identification and molecular docking analysis of active ingredients with medicinal properties from edible Baccaurea sapida

    PubMed Central

    Mann, Sonia; Sharma, Ankita; Biswas, Sagarika; Gupta, Rajinder K

    2015-01-01

    Underutilized plant species has started changing the conception of plants by expanding the use well beyond from foods and fibers to rich source of medicinally important secondary metabolites. Bioactive compounds from natural sources are gaining importance as potential drug candidates towards many inflammatory conditions like Rheumatoid Arthritis (RA). The focus of the present study has been centred to reveal the anti-inflammatory potential of an underutilized fruits of B. sapida. Further efforts towards its medicinal significance may provide relieve from symptoms of RA by reducing the side effects that are observed in available medications. Total 10 compounds in fruit crude methanol extract were identified and quantified by LC-MS/MS analysis followed by the agar well diffusion method for their anti microbial activity. Among all studied micro organism S. aureus was found to surmount the inflammation in RA through domain B of surface protein A (Staphylococcal surface protein A). Identified compounds (having anti-inflammatory properties) were scrutinized for their toxicity and quantitative structure–activity relationship (QSAR) using lazer toxicity and Molinspiration servers respectively. Further, docking studies have been carried out between domain B and studied compounds using AutoDock. Out of 6 anti-inflammtory compounds, quercetin has been identified as the most potent compound in reference to its inhibitory constant (47.01) and binding energy (-5.90 kcal/mol) to bacterial protein. Our data suggest that methanol extract of B. sapida fruit posses medicinally significant anti-inflammatory compounds and thus justifies the use of this fruit as folklore medicine for preventing inflammation related diseases. PMID:26527853

  13. Study of static and dynamic magnetic properties of Fe nanoparticles composited with activated carbon

    NASA Astrophysics Data System (ADS)

    Pal, Satyendra Prakash; Kaur, Guratinder; Sen, P.

    2016-05-01

    Nanocomposite of Fe nanoparticles with activated carbon has been synthesized to alter the magnetic spin-spin interaction and hence study the dilution effect on the static and dynamic magnetic properties of the Fe nanoparticle system. Transmission electron microscopic (TEM) image shows the spherical Fe nanoparticles dispersed in carbon matrix with 13.8 nm particle size. Temperature dependent magnetization measurement does not show any blocking temperature at all, right up to the room temperature. Magnetic hysteresis curve, taken at 300K, shows small value of the coercivity and this small hysteresis indicates the presence of an energy barrier and inherent magnetization dynamics. Langevin function fitting of the hysteresis curve gives almost similar value of particle size as obtained from TEM analysis. Magnetic relaxation data, taken at a temperature of 100K, were fitted with a combination of two exponentially decaying function. This diluted form of nanoparticle system, which has particles size in the superparamagnetic limit, behaves like a dilute ensemble of superspins with large value of the magnetic anisotropic barrier.

  14. Polyphenol oxidase activity and antioxidant properties of Yomra apple (Malus communis L.) from Turkey.

    PubMed

    Can, Zehra; Dincer, Barbaros; Sahin, Huseyin; Baltas, Nimet; Yildiz, Oktay; Kolayli, Sevgi

    2014-12-01

    In this study, firstly, antioxidant and polyphenol oxidase (PPO) properties of Yomra apple were investigated. Seventeen phenolic constituents were measured by reverse phase-high-performance liquid chromatography (RP-HPLC). Total phenolic compounds (TPCs), ferric reducing antioxidant power (FRAP) and 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging activities were performed to measure antioxidant capacity. Some kinetic parameters (Km, Vmax), and inhibition behaviors against five different substrates were measured in the crude extract. Catechin and chlorogenic acid were found as the major components in the methanolic extract, while ferulic acid, caffeic acid, p-hydroxybenzoic acid, quercetin and p-coumaric acid were small quantities. Km values ranged from 0.70 to 10.10 mM in the substrates, and also 3-(4-hydroxyphenyl) propanoic acid (HPPA) and L-DOPA showed the highest affinity. The inhibition constant of Ki were ranged from 0.05 to 14.90 mM against sodium metabisulphite, ascorbic acid, sodium azide and benzoic acid, while ascorbic acid and sodium metabisulphite were the best inhibitors.

  15. Solubilizing properties of new surface-active agents, products of catalytic oxyethylation of cholic acid.

    PubMed

    Kołodziejczyk, Michał Krzysztof; Nachajski, Michal Jakub; Lukosek, Marek; Zgoda, Marian Mikołaj

    2013-01-01

    Solubilizing properties of aqueous solutions of a series of surface-active agents, products of oxyethylation of cholic acid, were examined in the present study. The content of oxyethylated segments determined by means of the 1H NMR method enabled the verification of the molecular mass of surfactants along with the calculation of the structural hydrophilic-lipophilic balance (HLB), the solubility parameter delta1/2, and the required solubility level of balance HLB(R). Viscosimetric measurements enabled the calculation of the limiting viscosity number, the content-average molecular mass, the effective volume, the hydrodynamic radius of the surfactant micelle and their equilibrium adducts with rutin, diclofenac and loratadine (BCS Class II and III). By means of the spectrophotometric method (UV) the amount of the solubilized diclofenac, loratadine and rutin (rutoside) was determined in the equilibrium system (saturated solution) in the environment of aqueous solutions of cholic acid derivatives of n(TE) = 20-70. The obtained results serve as a basis for determining the solubilization mechanism of lipophilic therapeutic products and indirectly for estimating the influence of the above process on pharmaceutical as well as biological availability of a micellar adduct from model drug forms (Lindbladt lithogenolitic index).

  16. Bioactive properties of commercialised pomegranate (Punica granatum) juice: antioxidant, antiproliferative and enzyme inhibiting activities.

    PubMed

    Les, Francisco; Prieto, Jose M; Arbonés-Mainar, Jose Miguel; Valero, Marta Sofía; López, Víctor

    2015-06-01

    Pomegranate juice and related products have long been used either in traditional medicine or as nutritional supplements claiming beneficial effects. Although there are several studies on this food plant, only a few studies have been performed with pomegranate juice or marketed products. The aim of this work is to evaluate the antioxidant effects of pomegranate juice on cellular models using hydrogen peroxide as an oxidizing agent or DPPH and superoxide radicals in cell free systems. The antiproliferative effects of the juice were measured on HeLa and PC-3 cells by the MTT assay and pharmacologically relevant enzymes (cyclooxygenases, xanthine oxidase, acetylcholinesterase and monoamine oxidase A) were selected for enzymatic inhibition assays. Pomegranate juice showed significant protective effects against hydrogen peroxide induced toxicity in the Artemia salina and HepG2 models; these effects may be attributed to radical scavenging properties of pomegranate as the juice was able to reduce DPPH and superoxide radicals. Moderate antiproliferative activities in HeLa and PC-3 cancer cells were observed. However, pomegranate juice was also able to inhibit COX-2 and MAO-A enzymes. This study reveals some mechanisms by which pomegranate juice may have interesting and beneficial effects in human health.

  17. Properties of spray pyrolised ZnO:Sn thin films and their antibacterial activity.

    PubMed

    Manoharan, C; Pavithra, G; Dhanapandian, S; Dhamodaran, P; Shanthi, B

    2015-04-15

    Tin doped zinc oxide (ZnO:Sn) thin films were deposited onto glass substrates by the spray pyrolysis technique with the substrate temperature 400 °C. The structural, optical, photoluminescence (PL) properties and morphological studies were investigated for the films deposited with various doping concentration (0, 2, 4, 6 and 8 at.%) of tin. The XRD results had shown that the films were polycrystalline ZnO with hexagonal wurtzite type structure and the crystallites in the films were oriented along (002) direction. Surface morphology of the films obtained by scanning electron microscope (SEM) exhibited the change in morphology with doping concentration and porous nature for the film with 6 at.% of tin. Atomic force microscopy (AFM) revealed nanometer sized particles with decreased surface roughness for Sn doping. Optical analysis exhibited the band gap value of 2.8 eV for ZnO:Sn (6 at.%) which was lower than the band gap value for undoped ZnO film (3.2 eV). The resistivity of 6 at.% of Sn doped film was 1.28×10(2) Ω cm with increase in the hall mobility and carrier concentration. The ZnO and Sn doped ZnO thin films exhibited antibacterial activity against Staphylococcus aureus. PMID:25686860

  18. Properties of spray pyrolised ZnO:Sn thin films and their antibacterial activity

    NASA Astrophysics Data System (ADS)

    Manoharan, C.; Pavithra, G.; Dhanapandian, S.; Dhamodaran, P.; Shanthi, B.

    2015-04-01

    Tin doped zinc oxide (ZnO:Sn) thin films were deposited onto glass substrates by the spray pyrolysis technique with the substrate temperature 400 °C. The structural, optical, photoluminescence (PL) properties and morphological studies were investigated for the films deposited with various doping concentration (0, 2, 4, 6 and 8 at.%) of tin. The XRD results had shown that the films were polycrystalline ZnO with hexagonal wurtzite type structure and the crystallites in the films were oriented along (0 0 2) direction. Surface morphology of the films obtained by scanning electron microscope (SEM) exhibited the change in morphology with doping concentration and porous nature for the film with 6 at.% of tin. Atomic force microscopy (AFM) revealed nanometer sized particles with decreased surface roughness for Sn doping. Optical analysis exhibited the band gap value of 2.8 eV for ZnO:Sn (6 at.%) which was lower than the band gap value for undoped ZnO film (3.2 eV). The resistivity of 6 at.% of Sn doped film was 1.28 × 102 Ω cm with increase in the hall mobility and carrier concentration. The ZnO and Sn doped ZnO thin films exhibited antibacterial activity against Staphylococcus aureus.