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21.
Stevioside is a diterpenoid glycoside consisting of an aglycone (steviol) and three glucose molecules. It is commonly used as an anti-hyperglycemic food because of its non-caloric property. Therefore, it is of interest to document the interactions of stevioside with AKT & PPAR-γ proteins using Autodock Vina PyRx docking techniques. Results of the docking studies indicate that stevioside had more than two hydrogen bond interactions with the AKT and PPAR γ protein for further consideration. 相似文献
22.
JAMES A. NICHOLLS SONJA PREUSS ALEXANDER HAYWARD GEORGE MELIKA GYÖRGY CSÓKA JOSÉ‐LUIS NIEVES‐ALDREY RICHARD R. ASKEW MAJID TAVAKOLI KARSTEN SCHÖNROGGE GRAHAM N. STONE 《Molecular ecology》2010,19(3):592-609
Little is known about the evolutionary history of most complex multi‐trophic insect communities. Widespread species from different trophic levels might evolve in parallel, showing similar spatial patterns and either congruent temporal patterns (Contemporary Host‐tracking) or later divergence in higher trophic levels (Delayed Host‐tracking). Alternatively, host shifts by natural enemies among communities centred on different host resources could disrupt any common community phylogeographic pattern. We examined these alternative models using two Megastigmus parasitoid morphospecies associated with oak cynipid galls sampled throughout their Western Palaearctic distributions. Based on existing host cynipid data, a parallel evolution model predicts that eastern regions of the Western Palaearctic should contain ancestral populations with range expansions across Europe about 1.6 million years ago and deeper species‐level divergence at both 8–9 and 4–5 million years ago. Sequence data from mitochondrial cytochrome b and multiple nuclear genes showed similar phylogenetic patterns and revealed cryptic genetic species within both morphospecies, indicating greater diversity in these communities than previously thought. Phylogeographic divergence was apparent in most cryptic species between relatively stable, diverse, putatively ancestral populations in Asia Minor and the Middle East, and genetically depauperate, rapidly expanding populations in Europe, paralleling patterns in host gallwasp species. Mitochondrial and nuclear data also suggested that Europe may have been colonized multiple times from eastern source populations since the late Miocene. Temporal patterns of lineage divergence were congruent within and across trophic levels, supporting the Contemporary Host‐tracking Hypothesis for community evolution. 相似文献
23.
Liebscher RS Richards RC Lewis JM Short CE Muise DM Driedzic WR Ewart KV 《Physiological and biochemical zoology : PBZ》2006,79(2):411-423
In winter, rainbow smelt (Osmerus mordax) accumulate glycerol and produce an antifreeze protein (AFP), which both contribute to freeze resistance. The role of differential gene expression in the seasonal pattern of these adaptations was investigated. First, cDNAs encoding smelt and Atlantic salmon (Salmo salar) phosphoenolpyruvate carboxykinase (PEPCK) and smelt glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were cloned so that all sequences required for expression analysis would be available. Using quantitative PCR, expression of beta actin in rainbow smelt liver was compared with that of GAPDH in order to determine its validity as a reference gene. Then, levels of glycerol-3-phosphate dehydrogenase (GPDH), PEPCK, and AFP relative to beta actin were measured in smelt liver over a fall-winter-spring interval. Levels of GPDH mRNA increased in the fall just before plasma glycerol accumulation, implying a driving role in glycerol synthesis. GPDH mRNA levels then declined during winter, well in advance of serum glycerol, suggesting the possibility of GPDH enzyme or glycerol conservation in smelt during the winter months. PEPCK mRNA levels rose in parallel with serum glycerol in the fall, consistent with an increasing requirement for amino acids as metabolic precursors, remained elevated for much of the winter, and then declined in advance of the decline in plasma glycerol. AFP mRNA was elevated at the onset of fall sampling in October and remained elevated until April, implying separate regulation from GPDH and PEPCK. Thus, winter freezing point depression in smelt appears to result from a seasonal cycle of GPDH gene expression, with an ensuing increase in the expression of PEPCK, and a similar but independent cycle of AFP gene expression. 相似文献
24.
TÜNDE TÓTH OTTÓ ZSIROS MIHÁLY KIS GYŐZŐ GARAB LÁSZLÓ KOVÁCS 《Plant, cell & environment》2012,35(12):2075-2086
Despite intense research, the mechanism of Cd2+ toxicity on photosynthesis is still elusive because of the multiplicity of the inhibitory effects and different barriers in plants. The quick Cd2+ uptake in Synechocystis PCC 6803 permits the direct interaction of cadmium with the photosynthetic machinery and allows the distinction between primary and secondary effects. We show that the CO2‐dependent electron transport is rapidly inhibited upon exposing the cells to 40 µm Cd2+ (50% inhibition in ~15 min). However, during this time we observe only symptoms of photosystem I acceptor side limitation and a build of an excitation pressure on the reaction centres, as indicated by light‐induced P700 redox transients, O2 polarography and changes in chlorophyll a fluorescence parameters. Inhibitory effects on photosystem II electron transport and the degradation of the reaction centre protein D1 can only be observed after several hours, and only in the light, as revealed by chlorophyll a fluorescence transients, thermoluminescence and immunoblotting. Despite the marked differences in the manifestations of these short‐ and long‐term effects, they exhibit virtually the same Cd2+ concentration dependence. These data strongly suggest a cascade mechanism of the toxic effect, with a primary effect in the dark reactions. 相似文献
25.
Ziyab AH Karmaus W Yousefi M Ewart S Schauberger E Holloway JW Zhang H Arshad SH 《PloS one》2012,7(3):e32721
Background
Immune specific genes as well as genes regulating the formation of skin barrier are major determinants for eczema manifestation. There is a debate as to whether allergic sensitization and filaggrin gene (FLG) variants lead to eczema or FLG variants and eczema increase the risk of allergic sensitization. To investigate the time-order between eczema and allergic sensitization with respect to FLG variants, data from a large prospective study covering infancy to late adolescence were analyzed.Methodology/Principal Findings
Repeated measurements of eczema and allergic sensitization (documented by skin prick tests) at ages 1, 2, 4, 10, and 18 years were ascertained in the Isle of Wight birth cohort (n = 1,456). Three transition periods were analyzed: age 1-or-2 to 4, 4 to 10, and 10 to 18 years. FLG variants were genotyped in 1,150 participants. Over the three transition periods, in temporal sequence analyses of initially eczema-free participants, the combined effect of FLG variants and allergic sensitization showed a 2.92-fold (95% CI: 1.47–5.77) increased risk ratio (RR) of eczema in subsequent examinations. This overall risk was more pronounced at a younger age (transition period 1-or-2 to 4, RR = 6.47, 95% CI: 1.96–21.33). In contrast, FLG variants in combination with eczema showed a weaker, but significant, risk ratio for subsequent allergic sensitization only up to 10 years of age.Conclusions/Significance
Taking the time order into account, this prospective study demonstrates for the first time, that a combination of FLG variants and allergic sensitization increased the risk of eczema in subsequent years. Also FLG variants interacted with eczema and increased the risk of subsequent allergic sensitization, which, was limited to the younger age. Hence, early restoration of defective skin barrier could prevent allergic sensitization and subsequently reduce the risk of eczema development. 相似文献26.
Jobin Mathew Savitha Balakrishnan Sherin Antony Pretty Mary Abraham CS Paulose 《Journal of biomedical science》2012,19(1):25
Abstact
Background
Gamma amino butyric acid (GABA), the principal inhibitory neurotransmitter in the cerebral cortex, maintains the inhibitory tones that counter balances neuronal excitation. When this balance is perturbed, seizures may ensue.Methods
In the present study, alterations of the general GABA, GABAA and GABAB receptors in the cerebral cortex of the epileptic rat and the therapeutic application of Bacopa monnieri were investigated.Results
Scatchard analysis of [3H]GABA, [3H]bicuculline and [3H]baclofen in the cerebral cortex of the epileptic rat showed significant decrease in Bmax (P < 0.001) compared to control. Real Time PCR amplification of GABA receptor subunits such as GABAAά1, GABAAγ, GABAAδ, GABAB and GAD where down regulated (P < 0.001) in epileptic rats. GABAAά5 subunit and Cyclic AMP responsible element binding protein were up regulated. Confocal imaging study confirmed the decreased GABA receptors in epileptic rats. Epileptic rats have deficit in radial arm and Y maze performance.Conclusions
Bacopa monnieri and Bacoside-A treatment reverses epilepsy associated changes to near control suggesting that decreased GABA receptors in the cerebral cortex have an important role in epileptic occurrence; Bacopa monnieri and Bacoside-A have therapeutic application in epilepsy management. 相似文献27.
Rosiglitazone stimulates nitric oxide synthesis in human aortic endothelial cells via AMP-activated protein kinase 总被引:1,自引:0,他引:1
Boyle JG Logan PJ Ewart MA Reihill JA Ritchie SA Connell JM Cleland SJ Salt IP 《The Journal of biological chemistry》2008,283(17):11210-11217
The thiazolidinedione anti-diabetic drugs increase activation of endothelial nitric-oxide (NO) synthase by phosphorylation at Ser-1177 and increase NO bioavailability, yet the molecular mechanisms that underlie this remain poorly characterized. Several protein kinases, including AMP-activated protein kinase, have been demonstrated to phosphorylate endothelial NO synthase at Ser-1177. In the current study we determined the role of AMP-activated protein kinase in rosiglitazone-stimulated NO synthesis. Stimulation of human aortic endothelial cells with rosiglitazone resulted in the time- and dose-dependent stimulation of AMP-activated protein kinase activity and NO production with concomitant phosphorylation of endothelial NO synthase at Ser-1177. Rosiglitazone stimulated an increase in the ADP/ATP ratio in endothelial cells, and LKB1 was essential for rosiglitazone-stimulated AMPK activity in HeLa cells. Infection of endothelial cells with a virus encoding a dominant negative AMP-activated protein kinase mutant abrogated rosiglitazone-stimulated Ser-1177 phosphorylation and NO production. Furthermore, the stimulation of AMP-activated protein kinase and NO synthesis by rosiglitazone was unaffected by the peroxisome proliferator-activated receptor-gamma inhibitor GW9662. These studies demonstrate that rosiglitazone is able to acutely stimulate NO synthesis in cultured endothelial cells by an AMP-activated protein kinase-dependent mechanism, likely to be mediated by LKB1. 相似文献
28.
Antifreeze proteins (AFPs) are produced by several cold-water fish species. They depress physiological freezing temperatures by inhibiting growth of ice crystals and, in so doing, permit the survival of these fish in seawater cooler than their normal freezing temperatures. The type II AFP from rainbow smelt (Osmerus mordax), which is a member of the C-type lectin superfamily, was characterized in terms of its Ca2+-binding quaternary structure and the role of its single N-linked oligosaccharide. The protein core of the smelt AFP, shown through sequence homology to be a C-type lectin carbohydrate-recognition domain, was found to be protease resistant. Smelt AFP was also shown to bind Ca2+, as determined by ruthenium red staining and a conformational change on Ca2+ binding detected by intrinsic fluorescence. The N-linked oligosaccharide was found to have no effect on protease resistance, dimerization, or antifreeze activity. Thus its role, if any, in the antifreeze function of this protein remains unknown. Smelt AFP was also shown to be a true intermolecular dimer composed of two separate subunits. This dimerization did not require the presence of N-linked oligosaccharide or bound Ca2+. Smelt AFP dimerization has implications for the effective solution concentration and measurement of its activity. This finding may also lead to new interpretation of the mechanism of ice-growth inhibition by this AFP. 相似文献
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