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排序方式: 共有380条查询结果,搜索用时 15 毫秒
41.
Antoinette?C?van der KuylEmail author Donato?LP?Ballasina Fokla?Zorgdrager 《BMC evolutionary biology》2005,5(1):29
Background
To help conservation programs of the endangered spur-thighed tortoise and to gain better insight into its systematics, genetic variation and evolution in the tortoise species Testudo graeca (Testudines: Testudinidae) was investigated by sequence analysis of a 394-nucleotide fragment of the mitochondrial 12S rRNA gene for 158 tortoise specimens belonging to the subspecies Testudo graeca graeca, Testudo graeca ibera, Testudo graeca terrestris, and a newly recognized subspecies Testudo graeca whitei. A 411-nucleotide fragment of the mitochondrial D-loop was additionally sequenced for a subset of 22 T. graeca, chosen because of their 12S gene haplotype and/or geographical origin. 相似文献42.
Sea urchin spermatozoa are model cells for studying signal transduction events underlying flagellar motility and the acrosome reaction. We previously described the sea urchin sperm receptor for egg jelly 1 (suREJ1) which consists of 1450 amino acids, has one transmembrane segment and binds to the fucose sulfate polymer of egg jelly to induce the sperm acrosome reaction. We also cloned suREJ3 which consists of 2681 amino acids and has 11 putative transmembrane segments. Both these proteins localize to the plasma membrane over the acrosomal vesicle. While cloning suREJ1, we found suREJ2, which consists of 1472 amino acids, has two transmembrane segments and is present in the entire sperm plasma membrane, but is concentrated over the sperm mitochondrion. Experimental evidence suggests that, unlike suREJ1 and suREJ3, suREJ2 does not project extracellularly from the plasma membrane, but is an intracellular plasma membrane protein. All three sea urchin sperm REJ proteins possess a protein module of > 900 amino acids, termed 'the REJ module', that is shared by the human autosomal dominant polycystic kidney disease protein, polycystin-1, and PKDREJ, a testis-specific protein in mammals whose function is unknown. In the present study, we describe the sequence, domain structure and localization of suREJ2 and speculate on its possible function. 相似文献
43.
Cyclin-dependent kinase 5 phosphorylates serine 31 of tyrosine hydroxylase and regulates its stability 总被引:2,自引:0,他引:2
Tyrosine hydroxylase (TH) is the rate-limiting enzyme in catecholamine biosynthesis, and its activity is regulated by phosphorylation in the N-terminal regulatory domain. The proline-directed serine/threonine kinase cyclin-dependent kinase 5 (cdk5) plays an important role in diverse neuronal processes. In the present study, we identify TH as a novel substrate of cdk5. We show that cdk5 phosphorylates TH at serine 31 and that this phosphorylation is associated with an increase in total TH activity. In transgenic mice with increased cdk5 activity, the immunoreactivity for phosphorylated TH at Ser-31 is enhanced in neurons of the substantia nigra, a brain region enriched with TH-positive neurons. In addition, we demonstrate that co-expression of cdk5 and its regulatory activator p35 with TH increases the stability of TH. Consistent with these findings, TH protein levels are reduced in cdk5 knock-out mice. Importantly, the TH activity and protein turnover of the phosphorylation-defective mutant TH S31A was not altered by cdk5 activity. Taken together, these data suggest that cdk5 phosphorylation of TH is an important regulator of TH activity through stabilization of TH protein levels. 相似文献
44.
Moy AB Blackwell K Wu MH Granger HJ 《American journal of physiology. Heart and circulatory physiology》2006,291(5):H2126-H2135
We report functional differences in constitutive and agonist-mediated endothelial barrier function between cultured primary and Clonetics human umbilical vein endothelial cells (pHUVEC and cHUVEC) grown in soluble growth factors and heparin. Basal transendothelial resistance (TER) was much lower in pHUVEC than in cHUVEC grown in medium supplemented with growth factors, such as basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and human epithelial growth factor (EGF), and heparin. On the basis of a numerical model of TER, the increased basal TER in cHUVEC was due to effects on cell-matrix adhesion and membrane capacitance. Heparin and bFGF increased constitutive TER in cultured pHUVEC, and heparin mediated additional increases in constitutive TER in pHUVEC supplemented with bFGF. EGF attenuated bFGF-mediated increases in TER. On the basis of the numerical model, in contrast to cHUVEC, heparin and bFGF augmented TER through effects on cell-cell adhesion and membrane capacitance in pHUVEC. Thrombin mediated quantitatively greater amplitude and a more sustained decline in TER in cultured cHUVEC than pHUVEC. Thrombin-mediated barrier dysfunction was attenuated in pHUVEC conditioned in EGF in the presence or absence of heparin. Thrombin-mediated barrier dysfunction was also attenuated when monolayers were exposed to low concentrations of heparin and further attenuated in the presence of bFGF. cAMP stimulation mediated differential attenuation of thrombin-mediated barrier dysfunction between pHUVEC and cHUVEC. VEGF displayed differential effects in TER in serum-free medium. Taken together, these data demonstrate marked differential regulation of constitutive and agonist-mediated endothelial barrier function in response to mitogens and heparin stimulation. 相似文献
45.
Breslin JW Sun H Xu W Rodarte C Moy AB Wu MH Yuan SY 《American journal of physiology. Heart and circulatory physiology》2006,290(2):H741-H750
Neutrophil-induced coronary microvascular barrier dysfunction is an important pathophysiological event in heart disease. Currently, the precise cellular and molecular mechanisms of neutrophil-induced microvascular leakage are not clear. The aim of this study was to test the hypothesis that rho kinase (ROCK) increases coronary venular permeability in association with elevated endothelial tension. We assessed permeability to albumin (P(a)) in isolated porcine coronary venules and in coronary venular endothelial cell (CVEC) monolayers. Endothelial barrier function was also evaluated by measuring transendothelial electrical resistance (TER) of CVEC monolayers. In parallel, we measured isometric tension of CVECs grown on collagen gels. Transference of constitutively active (ca)-ROCK protein into isolated coronary venules or CVEC monolayers caused a significant increase in P(a) and decreased TER in CVECs. The ROCK inhibitor Y-27632 blocked the ca-ROCK-induced changes. C5a-activated neutrophils (10(6)/ml) also significantly elevated venular P(a), which was dose-dependently inhibited by Y-27632 and a structurally distinct ROCK inhibitor, H-1152. In CVEC monolayers, activated neutrophils increased permeability with a concomitant elevation in isometric tension, both of which were inhibited by Y-27632 or H-1152. Treatment with ca-ROCK also significantly increased CVEC monolayer permeability and isometric tension, coupled with actin polymerization and elevated phosphorylation of myosin regulatory light chain on Thr18/Ser19. The data suggest that during neutrophil activation, ROCK promotes microvascular leakage in association with actin-myosin-mediated tension development in endothelial cells. 相似文献
46.
DiDonato M Krishna SS Schwarzenbacher R McMullan D Jaroszewski L Miller MD Abdubek P Agarwalla S Ambing E Axelrod H Biorac T Chiu HJ Deacon AM Elsliger MA Feuerhelm J Godzik A Grittini C Grzechnik SK Hale J Hampton E Haugen J Hornsby M Klock HE Knuth MW Koesema E Kreusch A Kuhn P Lesley SA Moy K Nigoghossian E Okach L Paulsen J Quijano K Reyes R Rife C Spraggon G Stevens RC van den Bedem H Velasquez J White A Wolf G Xu Q Hodgson KO Wooley J Wilson IA 《Proteins》2006,63(1):256-260
47.
Han GW Sri Krishna S Schwarzenbacher R McMullan D Ginalski K Elsliger MA Brittain SM Abdubek P Agarwalla S Ambing E Astakhova T Axelrod H Canaves JM Chiu HJ DiDonato M Grzechnik SK Hale J Hampton E Haugen J Jaroszewski L Jin KK Klock HE Knuth MW Koesema E Kreusch A Kuhn P Miller MD Morse AT Moy K Nigoghossian E Oommachen S Ouyang J Paulsen J Quijano K Reyes R Rife C Spraggon G Stevens RC van den Bedem H Velasquez J Wang X West B White A Wolf G Xu Q Hodgson KO Wooley J Deacon AM Godzik A 《Proteins》2006,64(4):1083-1090
48.
Patrik Kraufvelin Sonja Salovius Hartvig Christie Frithjof E. Moy Rolf Karez Morten F. Pedersen 《Aquatic Botany》2006
This study, conducted in mesocosms, natural field sites, and in laboratory aquaria, showed that eutrophication altered the nutrient status and dominance patterns among marine macroalgae, which in turn, stimulated gammaridean density. Gammaridean abundance correlated positively with both nutrient addition and the amount of green algae (also stimulated by nutrient enrichment). Path analysis indicated that the direct effect of nutrients on gammaridean density was of less importance than the indirect effect through increased production of green algae. In cage colonisation experiments, either in the field or in a control mesocosm kept under ambient nutrient conditions, more gammarids colonised nutrient enriched algae (E-algae) than algae with ambient nutrient levels (A-algae). Gammarus locusta generally grew faster on nutrient enriched algal specimens and when reared on green rather than on brown algae (fucoids). The nutrient status of periphytic algae did not affect gammaridean growth significantly, but the number of egg-carrying females (and thus egg production) was significantly higher among gammarids reared on E-periphyton. The gammaridean habitat preference order (red > green > brown > periphyton) was almost the reverse of their growth rate in feeding assays (periphyton > green > brown). This implies that macroalgae may be more important as a habitat than as a food source for these animals, which then have to become mobile in search of optimal food items. In this process, algal nutrient content was important as the gammarids in our study actively chose high quality nutrient-rich food, which, in addition, increased their fitness. Stimulated growth rates and egg production may ultimately lead to population increase, which, combined with the preference for high nutrient food items may dampen the initial effect of nutrient enrichment (i.e. blooms of green macroalgae) in shallow coastal waters. 相似文献
49.
Background
Hydrophobic protein from soybean (HPS) is an 8 kD cysteine-rich polypeptide that causes asthma in persons allergic to soybean dust. HPS is synthesized in the pod endocarp and deposited on the seed surface during development. Past evidence suggests that the protein may mediate the adherence or dehiscence of endocarp tissues during maturation and affect the lustre, or glossiness of the seed surface. 相似文献50.