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141.
Lipidomic changes during different growth stages of Nitzschia closterium f. minutissima 总被引:3,自引:0,他引:3
Xiaoling Su Jilin Xu Xiaojun Yan Peng Zhao Juanjuan Chen Chengxu Zhou Fang Zhao Shuang Li 《Metabolomics : Official journal of the Metabolomic Society》2013,9(2):300-310
Ultra Performance Liquid Chromatography-Electrospray ionization-Quadrupole-Time of Flight Mass Spectrometry (UPLC-ESI-Q-TOF–MS) is a powerful lipidomic tool. In this study, we developed a UPLC/Q-TOF–MS based method to investigate the lipid metabolomic changes in different growth phases of Nitzschia closterium f. minutissima. The data classification and biomarker selection were carried out by using multivariate statistical analysis, including principal components analysis (PCA), projection to latent structures with discriminant analysis (PLS-DA), and orthogonal projection to latent structures with discriminant analysis (OPLS-DA). We discovered that the intercellular lipid metabolites were significantly different among exponential, early stationary and late stationary phases. Thirty-one lipid molecules were selected and identified as putative biomarkers, including free fatty acid, Harderoporphyrin, phosphatidylglycerol, 1,2-diacyglycerl-3-O-4′-(N,N-trimethy)-homoserine, triacylglycerol, cholesterol, sulfoquinovosyldiacylglycerol, lyso-sulfoquinovosyldiacylglycerol, monogalactosyldiacylglycerol, digalactosyldiacylglycerol and lyso-digalactosyldiacylglycerol. These lipids have been shown previously to function in energy storage, membrane stability and photosynthesis efficiency during the growth of diatoms. Further analysis on the putative biomarkers demonstrated that nitrate starvation played critical role in the transition from exponential phase to stationary phase in N. closterium. This study is the first one to explore the lipidomic changes of microalgae in different growth phases, which promotes better understanding of their physiology and ecology. 相似文献
142.
Qu Z Yang Z Cui N Zhu G Liu C Xu H Chanchevalap S Shen W Wu J Li Y Jiang C 《The Journal of biological chemistry》2000,275(41):31573-31580
Ion channels play an important role in cellular functions, and specific cellular activity can be produced by gating them. One important gating mechanism is produced by intra- or extracellular ligands. Although the ligand-mediated channel gating is an important cellular process, the relationship between ligand binding and channel gating is not well understood. It is possible that ligands are involved in the interactions of different protein domains of the channel leading to opening or closing. To test this hypothesis, we studied the gating of Kir2.3 (HIR) by intracellular protons. Our results showed that hypercapnia or intracellular acidification strongly inhibited these channels. This effect relied on both the N and C termini. The CO(2)/pH sensitivities were abolished or compromised when one of the intracellular termini was replaced. Using purified N- and C-terminal peptides, we found that the N and C termini bound to each other in vitro. Although their binding was weak at pH 7.4, stronger binding was seen at pH 6.6. Two short sequences in the N and C termini were found to be critical for the N/C-terminal interaction. Interestingly, there was no titratable residue in these motifs. To identify the potential protonation sites, we systematically mutated most histidine residues in the intracellular N and C termini. We found that mutations of several histidine residues in the C but not the N terminus had a major effect on channel sensitivities to CO(2) and pH(i). These results suggest that at acidic pH, protons appear to interact with the C-terminal histidine residues and present the C terminus to the N terminus. Consequentially, these two intracellular termini bound to each other through two short motifs and closed the channel. Thus, a novel mechanism for K(+) channel gating is demonstrated, which involves the N- and C-terminal interaction with protons as the mediator. 相似文献
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Genome-wide regulation of 5hmC, 5mC, and gene expression by Tet1 hydroxylase in mouse embryonic stem cells 总被引:2,自引:0,他引:2
Xu Y Wu F Tan L Kong L Xiong L Deng J Barbera AJ Zheng L Zhang H Huang S Min J Nicholson T Chen T Xu G Shi Y Zhang K Shi YG 《Molecular cell》2011,42(4):451-464
DNA methylation at the 5 position of cytosine (5mC) in the mammalian genome is a key epigenetic event critical for various cellular processes. The ten-eleven translocation (Tet) family of 5mC-hydroxylases, which convert 5mC to 5-hydroxymethylcytosine (5hmC), offers a way for dynamic regulation of DNA methylation. Here we report that Tet1 binds to unmodified C or 5mC- or 5hmC-modified CpG-rich DNA through its CXXC domain. Genome-wide mapping of Tet1 and 5hmC reveals mechanisms by which Tet1 controls 5hmC and 5mC levels in mouse embryonic stem cells (mESCs). We also uncover a comprehensive gene network influenced by Tet1. Collectively, our data suggest that Tet1 controls DNA methylation both by binding to CpG-rich regions to prevent unwanted DNA methyltransferase activity, and by converting 5mC to 5hmC through hydroxylase activity. This Tet1-mediated antagonism of CpG methylation imparts differential maintenance of DNA methylation status at Tet1 targets, ultimately contributing to mESC differentiation and the onset of embryonic development. 相似文献
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白腐菌对染料脱色和降解作用的研究进展 总被引:2,自引:0,他引:2
白腐菌应用于废水处理始于二十世纪八十年代。本文对印染废水的处理方法、白腐菌及其对污染物的降解机理作了简要概述 ,着重介绍了白腐菌对染料脱色和降解作用的研究进展。白腐菌对染料的脱色解降作用机理有部分尚待进一步研究 ;同时 ,白腐菌的吸附作用亦不容忽视。 相似文献
150.
Down-regulated expression of atypical PKC-binding domain deleted asip isoforms in human hepatocellular carcinomas 总被引:1,自引:0,他引:1
INTRODUCTIONCell polarity is the reflection of complex mechanisms that establish and maintain the functionally specialized regions in the plasma membrane and cytoplasm, and is fundamentally important for differentiation, proliferation, morphogenesis and other functions of simple and complicated organisms[1].Molecular mechanisms of cell polarity during animal development have been analyzed mainly in the nematode Caenorhabditis elegans and the fruit fly Drosophila melanogaster[2]. In early … 相似文献