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81.
Electron acceptors for anaerobic oxidation of methane drive microbial community structure and diversity in mud volcanoes 下载免费PDF全文
Ge Ren Anzhou Ma Yanfen Zhang Ye Deng Guodong Zheng Xuliang Zhuang Guoqiang Zhuang Danielle Fortin 《Environmental microbiology》2018,20(7):2370-2385
Mud volcanoes (MVs) emit globally significant quantities of methane into the atmosphere, however, methane cycling in such environments is not yet fully understood, as the roles of microbes and their associated biogeochemical processes have been largely overlooked. Here, we used data from high‐throughput sequencing of microbial 16S rRNA gene amplicons from six MVs in the Junggar Basin in northwest China to quantify patterns of diversity and characterize the community structure of archaea and bacteria. We found anaerobic methanotrophs and diverse sulfate‐ and iron‐reducing microbes in all of the samples, and the diversity of both archaeal and bacterial communities was strongly linked to the concentrations of sulfate, iron and nitrate, which could act as electron acceptors in anaerobic oxidation of methane (AOM). The impacts of sulfate/iron/nitrate on AOM in the MVs were verified by microcosm experiments. Further, two representative MVs were selected to explore the microbial interactions based on phylogenetic molecular ecological networks. The sites showed distinct network structures, key species and microbial interactions, with more complex and numerous linkages between methane‐cycling microbes and their partners being observed in the iron/sulfate‐rich MV. These findings suggest that electron acceptors are important factors driving the structure of microbial communities in these methane‐rich environments. 相似文献
82.
我国有罂粟属植物12种,新疆有10种,其中6种属于高山罂粟组。对新疆高山罂粟组植物的花葶进行了解剖研究,并用扫描电镜观察了花粉形态,结果表明,花葶中维管束的数量及排列方式在各种间存在着差异,可以作为一个鉴定特征。花粉上的小刺密度在放大12000倍时,在有种间存在着明显差异,可分类提供微观佐证。 相似文献
83.
Mst1 (mammalian sterile 20-like kinase 1) is a ubiquitously expressed serine/threonine kinase and its activation in the heart causes cardiomyocyte apoptosis and dilated cardiomyopathy. Its myocardial substrates, however, remain unknown. In a yeast two-hybrid screen of a human heart cDNA library with a dominant-negative Mst1 (K59R) mutant used as bait, cTn [cardiac Tn (troponin)] I was identified as an Mst1-interacting protein. The interaction of cTnI with Mst1 was confirmed by co-immunoprecipitation in both co-transfected HEK-293 cells (human embryonic kidney cells) and native cardiomyocytes, in which cTnI interacted with full-length Mst1, but not with its N-terminal kinase fragment. in vitro phosphorylation assays demonstrated that cTnI is a sensitive substrate for Mst1. In contrast, cTnT was phosphorylated by Mst1 only when it was incorporated into the Tn complex. MS analysis indicated that Mst1 phosphorylates cTnI at Thr(31), Thr(51), Thr(129) and Thr(143). Substitution of Thr(31) with an alanine residue reduced Mst1-mediated cTnI phosphorylation by 90%, whereas replacement of Thr(51), Thr(129) or Thr(143) with alanine residues reduced Mst1-catalysed cTnI phosphorylation by approx. 60%, suggesting that Thr(31) is a preferential phosphorylation site for Mst1. Furthermore, treatment of cardiomyocytes with hydrogen peroxide rapidly induced Mst1-dependent phosphorylation of cTnI at Thr(31). Protein epitope analysis and binding assays showed that Mst1-mediated phosphorylation modulates the molecular conformation of cTnI and its binding affinity to TnT and TnC, thus indicating functional significances. The results of the present study suggest that Mst1 is a novel mediator of cTnI phosphorylation in the heart and may contribute to the modulation of myofilament function under a variety of physiological and pathophysiological conditions. 相似文献
84.
85.
Wu X Weiszmann J Ge H Baribault H Stevens J Hawkins N Vonderfecht S Gardner J Gupte J Sheng J Wang M Li Y 《Journal of molecular biology》2012,418(1-2):82-89
Three fibroblast growth factor (FGF) molecules, FGF19, FGF21, and FGF23, form a unique subfamily that functions as endocrine hormones. FGF19 and FGF21 can regulate glucose, lipid, and energy metabolism, while FGF23 regulates phosphate homeostasis. The FGF receptors and co-receptors for these three FGF molecules have been identified, and domains important for receptor interaction and specificity determination are beginning to be elucidated. However, a number of questions remain unanswered, such as the identification of fibroblast growth factor receptor responsible for glucose regulation. Here, we have generated a variant of FGF23: FGF23-21c, where the C-terminal domain of FGF23 was replaced with the corresponding regions from FGF21. FGF23-21c showed a number of interesting and unexpected properties in vitro. In contrast to wild-type FGF23, FGF23-21c gained the ability to activate FGFR1c and FGFR2c in the presence of βKlotho and was able to stimulate glucose uptake into adipocytes in vitro and lower glucose levels in ob/ob diabetic mice model to similar extent as FGF21 in vivo. These results suggest that βKlotho/FGFR1c or FGFR2c receptor complexes are sufficient for glucose regulation. Interestingly, without the FGF23 C-terminal domain, FGF23-21c was still able to activate fibroblast growth factor receptors in the presence of αKlotho. This suggests not only that sequences outside of the C-terminal region may also contribute to the interaction with co-receptors but also that FGF23-21c may be able to regulate both glucose and phosphate metabolisms. This raises an interesting concept of designing an FGF molecule that may be able to address multiple diseases simultaneously. Further understanding of FGF/receptor interactions may allow the development of exciting opportunities for novel therapeutic discovery. 相似文献
86.
87.
Studies on antigens of human lung adenocarcinoma with McAb LC-1] 总被引:1,自引:0,他引:1
The soluble antigens extracted from both human lung adenocarcinoma cell line SPC-A-1, and normal adult lung tissue with non-idet P-40 were subjected to 10% SDS-PAGE. The number of bands distinguishable by naked eyes of lung adenocarcinoma are 57, in which 4 bands are more significant. The bands of normal human lung tissue are 52, in which 2 bands are more significant. The molecular weights of these bands mainly are within 30 to 94 KD The thin layer chromatographs of these two antigenic extracts have shown that there is difference in their sugar content, but both of them shown little sialic acid. The Immunoblot pattern of McAb LC-1 reacted with the extracts of SPC-A-1 cells shows that all of 3 bands detected can be stained by alcian blue, indicating that they are glycoproteins. However, of them two bands, M. W. of 70 KD and 51 KD can also be stained by Sudan Black B, indicating that these two bands are glycolipoproteins. The ganglioside and neutral glycolipid can inhibit the binding of LC-1 with the extract of SPC-A-1 cells. The results indicate that the epitopes of SPC-A-1 cell extract reacted with McAb LC-1 are probably located in the polysaccharide. 相似文献
88.
用免疫细胞化学和原位杂交技术探讨G、D细胞及胃泌素mRNA与肠化生的关系。标本来自胃镜活检的胃粘膜。结果显示,在与大肠化生区相邻的胃粘膜,G细胞突变消失,假幽门腺化生也缺乏G细胞,而淖肠化生仍保留少数G细胞;D细胞不仅见于小肠化生,而且也出现在假幽门腺化生以及某些大肠化生区。胃泌素mRNA仅限于G细胞分布区,未出现在大肠化生区和假幽门腺化生区,G细胞及胃泌素mRNA在大肠化生区的消失,可能由于局部杯状细胞分泌的硫酸粘蛋白改变了局部的微环境,从而影响了G细胞的分化与发育,至于假幽门腺化生区G细胞及胃泌素mRNA消失的原因还不清楚,应继续研究。 相似文献
89.
1859年,达尔文的著作《物种起源》改变了人们对自己的看法:在1859年以前,人是上帝创造的产物:在1859年以后,人是自然选择的产物。而达尔文主张人是自然界的一部分。而不是在自然之外。他和T·H赫胥黎提出,人和大猿特别是非洲猿有近密的亲缘关系。E·海克尔甚至画出了包括某些似猿的人类祖先的系统树。然而,在20世纪,许多人类学家还是相信,人是独特的,是一种全新的生物。他们要寻找人类进化的特殊类型的解释。他们提出,脑必定引领着进化的方向,认为人和现代非洲猿之间的相似性是平行进化所造成的。后来,分子生物学的和化石的证据证实了达尔文原先的观点。今天,达尔文的理论对人类社会生活仍然具有重大意义。 相似文献
90.
目的:研究肌肽对低氧所致大鼠血管内皮细胞损伤的影响。方法:建立低氧条件下大鼠血管内皮细胞损伤模型,用MTT法观察肌肽对低氧损伤的血管内皮细胞活性的影响,测定细胞培养基中LDH活力,并对细胞骨架进行考马斯亮蓝R-250染色观测其细胞结构。结果:浓度为10mmol/L~20mmol/L肌肽孵育血管内皮细胞6h后,可以抑制缺氧12h和24h引起的血管内皮细胞活性下降,同时减少LDH的释放,保持细胞骨架完整。结论:肌肽对低氧所致的血管内皮细胞损伤具有保护作用。 相似文献