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91.
Jiang SX Lertvorachon J Hou ST Konishi Y Webster J Mealing G Brunette E Tauskela J Preston E 《The Journal of biological chemistry》2005,280(40):33811-33818
Minocycline is a potent neuroprotective tetracycline in animal models of cerebral ischemia. We examined the protective properties of chlortetracycline (CTC) and demeclocycline (DMC) and showed that these two tetracyclines were also potent neuroprotective against glutamate-induced neuronal death in vitro and cerebral ischemia in vivo. However, CTC and DMC appeared to confer neuroprotection through a unique mechanism compared with minocycline. Rather than inhibiting microglial activation and caspase, CTC and DMC suppressed calpain activities. In addition, CTC and DMC only weakly antagonized N-methyl-D-aspartate (NMDA) receptor activities causing 16 and 14%, respectively, inhibition of NMDA-induced whole cell currents and partially blocked NMDA-induced Ca2+ influx, commonly regarded as the major trigger of neuronal death. In vitro and in vivo experiments demonstrated that the two compounds selectively inhibited the activities of calpain I and II activated following glutamate treatment and cerebral ischemia. In contrast, minocycline did not significantly inhibit calpain activity. Taken together, these results suggested that CTC and DMC provide neuroprotection through suppression of a rise in intracellular Ca2+ and inhibition of calpains. 相似文献
92.
Bani-Yaghoub M Tremblay R Voicu R Mealing G Monette R Py C Faid K Sikorska M 《Biotechnology and bioengineering》2005,92(3):336-345
Neural networks are formed by accurate connectivity of neurons and glial cells in the brain. These networks employ a three-dimensional bio-surface that both assigns precise coordinates to cells during development and facilitates their connectivity and functionality throughout life. Using specific topographic and chemical features, we have taken steps towards the development of poly(dimethylsiloxane; PDMS) neurochips that can be used to generate and study synthetic neural networks. These neurochips have micropatterned structures that permit adequate cell positioning and support cell survival. Within days of plating, cells differentiate into neurons displaying excitability and communication, as evidenced by intracellular calcium oscillations and action potentials. The structural and functional capacities of such simple neural networks open up new opportunities to study synaptic communication and plasticity. 相似文献
93.
Valizadeh M Schenk G Nash K Oddie GW Guddat LW Hume DA de Jersey J Burke TR Hamilton S 《Archives of biochemistry and biophysics》2004,424(2):154-162
Purple acid phosphatases are metal-containing hydrolases. While their precise biological role(s) is unknown, the mammalian enzyme has been linked in a variety of biological circumstances (e.g., osteoporosis) with increased bone resorption. Inhibition of the human enzyme is a possible strategy for the treatment of bone-resorptive diseases such as osteoporosis. Previously, we determined the crystal structure of pig purple acid phosphatase to 1.55A and we showed that it is a good model for the human enzyme. Here, a study of the pH dependence of its kinetic parameters showed that the pig enzyme is most efficient at pH values similar to those encountered in the osteoclast resorptive space. Based on the observation that phosphotyrosine-containing peptides are good substrates for pig purple acid phosphatase, peptides containing a range of phosphotyrosine mimetics were synthesized. Kinetic analysis showed that they act as potent inhibitors of mammalian and plant purple acid phosphatases, with the best inhibitors exhibiting low micromolar inhibition constants at pH 3-5. These compounds are thus the most potent organic inhibitors yet reported for the purple acid phosphatases. 相似文献
94.
Pain DJ Green RE Giebetaing B Kozulin A Poluda A Ottosson U Flade M Hilton GM 《Oecologia》2004,138(2):168-174
Understanding the links between breeding and wintering areas of migratory species has important ecological and conservation implications. Recently, stable isotope technology has been used to further our understanding. Stable isotope ratios vary geographically with a range of biogeochemical factors and isotope profiles in organisms reflect those in their food and environment. For inert tissues like feathers, isotope profiles reflect the environment in which they were formed. Following large-scale habitat destruction, the globally threatened aquatic warbler Acrocephalus paludicola has a fragmented breeding population across central Europe, largely in Belarus, Poland and Ukraine. The species sub-Saharan African wintering grounds have not yet been discovered, and this significantly hampers conservation efforts. Aquatic warblers grow their flight feathers on their wintering grounds, and we analysed stable isotope ratios (15N, 13C, D) in rectrices of adults from six main breeding sites (subpopulations) across Europe to determine whether different breeding subpopulations formed a single mixed population on the wintering grounds. 15N varies considerably with dietary trophic level and environmental factors, and D with the D in rainfall; neither varied between aquatic warbler subpopulations. Uniform feather 15N signatures suggest no major variation in dietary trophic level during feather formation. High variance and inter-annual differences in mean D values hinder interpretation of these data. Significant differences in mean 13C ratios existed between subpopulations. We discuss possible interpretations of this result, and consider differences in moulting latitude of different subpopulations to be the most parsimonious. 13C in plants and animals decreases with latitude, along a steep gradient in sub-Saharan Africa. Birds from the most north-westerly breeding subpopulation (Karsibor, Poland) had significantly lower variance in 13C and 15N than birds from all other sites, suggesting either that birds from Karsibor are less geographically dispersed during moult, or moult in an area with less isotopic heterogeneity. Mean 13C signatures from winter-grown feathers of different subpopulations were positively correlated with the latitude and longitude of breeding sites, suggesting a strong relationship between European breeding and African winter moulting latitudes. The use of stable isotopes provides novel insights into migratory connectivity and migration patterns in this little-known threatened species. 相似文献
95.
SCARFACE encodes an ARF-GAP that is required for normal auxin efflux and vein patterning in Arabidopsis
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Sieburth LE Muday GK King EJ Benton G Kim S Metcalf KE Meyers L Seamen E Van Norman JM 《The Plant cell》2006,18(6):1396-1411
To identify molecular mechanisms controlling vein patterns, we analyzed scarface (sfc) mutants. sfc cotyledon and leaf veins are largely fragmented, unlike the interconnected networks in wild-type plants. SFC encodes an ADP ribosylation factor GTPase activating protein (ARF-GAP), a class with well-established roles in vesicle trafficking regulation. Quadruple mutants of SCF and three homologs (ARF-GAP DOMAIN1, 2, and 4) showed a modestly enhanced vascular phenotype. Genetic interactions between sfc and pinoid and between sfc and gnom suggest a possible function for SFC in trafficking of auxin efflux regulators. Genetic analyses also revealed interaction with cotyledon vascular pattern2, suggesting that lipid-based signals may underlie some SFC ARF-GAP functions. To assess possible roles for SFC in auxin transport, we analyzed sfc roots, which showed exaggerated responses to exogenous auxin and higher auxin transport capacity. To determine whether PIN1 intracellular trafficking was affected, we analyzed PIN1:green fluorescent protein (GFP) dynamics using confocal microscopy in sfc roots. We found normal PIN1:GFP localization at the apical membrane of root cells, but treatment with brefeldin A resulted in PIN1 accumulating in smaller and more numerous compartments than in the wild type. These data suggest that SFC is required for normal intracellular transport of PIN1 from the plasma membrane to the endosome. 相似文献
96.
Graham RL Pollock CE O'Loughlin SN Ternan NG Weatherly DB Jackson PJ Tarleton RL McMullan G 《Journal of proteome research》2006,5(11):3145-3153
We report the first large-scale gel-free proteomic analysis of the soluble subproteome of the emerging pathogen Ochrobactrum anthropi. Utilizing our robust offline multidimensional protein identification protocol, a total of 57 280 peptides were initially identified utilizing automated MS/MS analysis software. We describe our investigation of the heuristic protein validation tool PROVALT and demonstrate its ability to increase the speed and accuracy of the curation process of large-scale proteomic datasets. PROVALT reduced our peptide list to 8517 identified peptides and further manual curation of these peptides led to a final list of 984 uniquely identified peptides that resulted in the positive identification of 249 proteins. These identified proteins were functionally classified and physiochemically characterized. A variety of typical "housekeeping" functions identified within the proteome included nucleic acid, amino and fatty acid anabolism and catabolism, glycolysis, TCA cycle, and pyruvate and selenoamino acid metabolism. In addition, a number of potential virulence factors of relevance to both plant and human disease were identified. 相似文献
97.
David Monticelli Ricardo Ceia Ruben Heleno Hugo Laborda Sergio Timóteo Daniel Jare?o Geoff M. Hilton Jaime A. Ramos 《Journal of Ornithology》2010,151(3):627-636
This paper reports analyses of a capture–mark–recapture (CMR) dataset of 149 Azores Bullfinches ringed on S?o Miguel island
(Azores) between 2005 and 2007, and recaptured–resighted on a monthly basis over a 4-year period (2005–2008) throughout their
breeding range. We examined the effect of time, age (adults vs. juveniles), gender (adult males and females), and environmental
covariates (temperature, rainfall, NAO index) on survival probabilities. The modelling found a high and constant monthly survival
probability (mean ± SE) estimated at 0.96 ± 0.01, similar between both adults and juveniles and independent of environmental
conditions and gender. These findings agree with expectations from island-based life-history theory where relatively mild
conditions and lack of predators should favour high survival rates to compensate for the low reproductive output. The annual
survival rate was estimated at 0.62, which was also consistent with this pattern when compared with survival estimates of
mainland bullfinch and passerine species on other subtropical islands obtained in similar CMR studies. Based on a canonical
estimator, the size of the studied population (mean ± SE) was estimated at 1608 ± 326 individuals. Given that the population
size was only around 120–400 individuals in the early 1990s, we suggest that the high survival probabilities currently applying
to this critically endangered species may have substantially contributed to the recent recovery of this population. Future
research studies on the species’ demography should continue to monitor survival in order to measure the effect of management
interventions currently taking place within the range of the Azores Bullfinch, including the restoration of the biodiversity
rich laurel forest, but also focusing on nest success, which is important for understanding population dynamics. 相似文献
98.
Wen-Quan Zou Jan Langeveld Xiangzhu Xiao Shugui Chen Patrick L. McGeer Jue Yuan Michael C. Payne Hae-Eun Kang John McGeehan Man-Sun Sy Neil S. Greenspan David Kaplan Gong-Xian Wang Piero Parchi Edward Hoover Geoff Kneale Glenn Telling Witold K. Surewicz Qingzhong Kong Jian-Ping Guo 《The Journal of biological chemistry》2010,285(18):13874-13884
99.
Sophie Constable Arana Parslow Geoff Dutton Tracey Rogers Carolyn Hogg 《Zoo biology》2006,25(2):137-144
This study investigated the feasibility and validity of using non‐invasively collected ice urine samples to measure cortisol concentrations in Weddell seals. Radio‐immunoassays were used to determine urinary cortisol, and spectrophotometric assay was used to determine creatinine concentrations. This allowed for urinary cortisol/creatinine ratios (UCCR) to be compared between pure urine and urine collected from the ice. Urinary cortisol/creatinine ratios values of ice urine proved an effective method of studying cortisol concentrations in Weddell seals as there was no difference between pure urine and ice urine UCCR values. There were no inter‐sexual or age‐related differences in UCCR values in either pure or ice urine. Zoo Biol 0:1–8, 2006. © 2006 Wiley‐Liss, Inc. 相似文献
100.
Watt MS Moore JR Façon JP Downes GM Clinton PW Coker G Davis MR Simcock R Parfitt RL Dando J Mason EG Bown HE 《Annals of botany》2006,98(4):765-775
Background and Aims Although density-specific stiffness,E/, (where E is Young's modulus and is wood density) is oftenassumed constant by the elastic similarity model, and in determinationof critical buckling height (Hcrit), few studies have testedthis assumption within species. Here this assumption is testedfor Pinus radiata growing across an environmental gradient,and theory is combined with data to develop a model of Young'smodulus. Methods Analyses use an extensive series of environmentalplots covering the range of climatic and edaphic conditionsover which P. radiata is grown in New Zealand. Reduced majoraxis regression was used to determine scaling exponents betweenloglog plots of Hcrit vs. groundline diameter (D), andE/ vs. D. Path analysis was used to identify significant directand indirect (through stem slenderness) edaphic and climaticinfluences on E. Key Results Density-specific stiffness exhibited 3-foldvariation. As E/ scaled positively with D, the exponent of 0·95between Hcrit and D exceeded the assumed value of 0·67under constant E/. The final path analysis model included meanair temperature in early autumn (Taut) and slenderness as significant(P < 0·05) positive direct influences on E. Tree leafarea index and Taut were indirectly associated with E throughtheir significant (P < 0·05) positive direct relationshipwith stem slenderness. Young's modulus was most sensitive toTaut, followed by stem slenderness then leaf area index, andthe final model explained 76 % of the variance in E. Conclusions The findings suggest that within speciesE/ variation may influence Hcrit and the scaling exponent betweenD and Hcrit so important in assumptions regarding allometricrelationships. The model presented may provide a useful meansof determining variation in E, E/ and Hcrit across environmentalgradients. 相似文献