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141.
内质网(endoplasmic reticulum,ER)是广泛存在于真核生物中的一类形态多样、功能重要的细胞器。内质网的连续膜系统由细胞核核膜、核周区域和外周区域组成。从形态上来看,内质网可以分为片状及管状两种结构,并且这两种形态又发挥着不同的生理功效。近年来的一些研究逐渐揭示了内质网这一复杂膜结构维持的机制,许多新发现的蛋白参与到内质网形态的维持过程中,其中整合膜蛋白reticulons和DP1/Yop1p既能诱导内质网管状结构的形成,又可能参与片状内质网的塑形,而atlastins和Sey1p则通过介导膜融合促进内质网管状网络的构建。更重要的是,一类称做遗传性痉挛性截瘫的人类神经退行性疾病与内质网形态的完整性有直接的关联。以近几年的研究结果为基础,对内质网膜形态的维持机制进行简要阐述。 相似文献
142.
Perinatal transmission of Human immunodeficiency virus(HIV),also called mother-to-child transmission(MTCT),accounts for 90% of infections in infants worldwide and occurs in 30%-45% of children born to untreated HIV-1 infected mothers.Among HIV-1 infected mothers,some viruses are transmitted from mothers to their infants while others are not.The relationship between virologic properties and the pathogenesis caused by HIV-1 remains unclear.Previous studies have demonstrated that one obvious source of selectiv... 相似文献
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145.
Smith-Lemli-Opitz syndrome, a congenital and developmental malformation disease, is typified by abnormal accumulation of 7-dehydrocholesterol (7DHC), the immediate precursor of cholesterol (CHOL), and depletion thereof. Knowledge of the effect of 7DHC on the biological membrane is, however, still fragmentary. In this study, large-scale atomistic molecular dynamics simulations, employing two distinct force fields, have been conducted to elucidate differences in the structural properties of a hydrated dimyristoylphosphatidylcholine bilayer due to CHOL and 7DHC. The present series of results indicate that CHOL and 7DHC possess virtually the same ability to condense and order membranes. Furthermore, the condensing and ordering effects are shown to be strengthened at increasing sterol concentrations. 相似文献
146.
Dynamic distribution of Ser-10 phosphorylated histone H3 in cytoplasm of MCF-7 and CHO cells during mitosis 总被引:3,自引:1,他引:2
The dynamic distribution of phosphorylated Histone H3 on Serl 0 (phospho-H3) in cells was investigated to determine its function during mitosis. Human breast adenocarcinoma cells MCF-7, and Chinese hamster cells CHO were analyzed by indirect immunofluorescence staining with an antibody against phospho-H3. We found that the phosphorylation begins at early prophase, and spreads throughout the chromosomes at late prophase. At metaphase, most of the phospho-H3 aggregates at the end of the condensed entity of chromosomes at equatorial plate. During anaphase and telophase,the fluorescent signal of phospho-H3 is detached from chromosomes into cytoplasm. At early anaphase, phospho-H3 shows ladder bands between two sets of separated chromosome, and forms “sandwich-like structure” when the chromosomes condensed. With the cleavage progressing, the “ladders” of the histone contract into a bigger bright dot. Then the histone aggregates and some of compacted microtubules in the midbody region are composed into a “bar-like”complex to separate daughter cells. The daughter cells seal their plasma membrane along with the ends of the “bar”,inside which locates microtubules and modified histones, to finish the cytokinesis and keep the “bar complex” out of the cells. The specific distribution and kinetics of phospho-H3 in cytoplasm suggest that the modified histones may take part in the formation of midbody and play a crucial role in cytokinesis. 相似文献
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148.
In order to further understand the coordination chemistry of diazamesocyclic systems, a series of mononuclear NiII complexes with 1,4-diazacycloheptane (DACH) functionalized by additional imidazole or pyridine donor pendants, including [NiL1](ClO4)2 · H2O (1), [NiL1Cl](ClO4) (2), [NiL2Cl](ClO4) · CH3OH (3), [NiL2Cl][NiL2](ClO4)3 (4) and [NiL3](ClO4)2 (5), where L1 = 1,4-bis(N-1-methylimidazol-2-yl-methyl)-1,4-diazacycloheptane, L2 = 1,4-bis(pyridyl-2-yl-methyl)-1,4-diazacycloheptane, and L3 = 1,4-bis-(imidazol-4-yl-methyl)-1,4-diazacycloheptane, have been prepared and characterized. A detailed study on the solid structures and solution spectra of these complexes indicates that tetradentate ligands L1, L2 and L3 would lead to new NiII complexes with different coordination environments in the solid states and solution. The N-methyl substituted imidazole functionalized ligand L1 forms green compound 2 and yellow product 1; while the pyridine functionalized ligand L2 affords red product 4 and green complex 3; the ligand L3 results in only one stable mononuclear NiII product 5. The solution behaviors of these interesting compounds were also investigated by UV-Vis technique. 相似文献
149.
Hui-Bo Zhou Wen Dong Dai-Zheng Liao Zong-Hui Jiang Shi-Ping Yan Peng Cheng 《Inorganica chimica acta》2005,358(12):3287-3292
Two novel 1D complexes, [Ni(hto){Au(CN)2}2][Ni(hto)](ClO4)2 · 4H2O (hto = 1,3,6,9,11,14-hexaazatricyclo[12.2.1.16,9]octadecane, in Scheme 1.) (1) and [Co(dien)2][{Au(CN)2}3] · 2H2O (dien = diethylenetriamine) (2) have been synthesized and characterized. The crystal structure of 1 confirmed the presence of nickel (II) chains via Au-Au interactions. The coordination geometry around the six-coordinate nickel (II) ion is slightly distorted octahedral with four nitrogen atoms of the macrocycle and two nitrogen atoms of the cyanides. The presence of Au-Au interactions have effectively increased the zero dimensional coordination polymer to a one dimensional system. In the complex 2, there are one cation, three anions, and two water molecules in the asymmetric unit. These components are interconnected through a combination of aurophilic attractions and hydrogen bonds and formed 1D chains. 相似文献
150.
Ethylene biosynthesis in higher plants is regulated developmentallyand environmentally. To investigate the regulation of ACC synthasegene expression, the promoters of Arabidopsis ACS genes, AtACS4,AtACS5, and AtACS7, were fused to a GUS reporter gene, and therecombinant transgenes were introduced into Arabidopsis to producethree groups of AtACS::GUS transgenic plants. Histochemic andfluorometric study of these transgenic plants revealed thatpromoters of AtACS4, AtACS, and AtACS7 are all active in dark-germinatedseedlings. AtACS5 has the highest promoter activity in leavesof 2-week-old light-grown seedlings among the three AtACS genesstudied. In the mature leaves, AtACS4 and AtACS7 genes are expressedin both veins and areoles, whereas AtACS5 is expressed at ahigher level in the areoles and epidermal cells surroundingtrichomes. The promoter activities of all these AtACS genesare found in the reproductive organs. AtACS5 and AtACS7 arehighly expressed in petals, sepals, carpels, stamens, caulineleaves, inflorescence stems, and siliques, while AtACS4 expressionis undetectable in the petals of open flowers. All three AtACSgenes are expressed in root tissue. In the 2-week-old light-grownArabidopsis, the AtACS4 promoter is responsive to the planthormones IAA, ethylene, and ABA, and to darkness and wounding;the AtACS5 promoter to IAA, ABA, salt, high temperature, andwounding; and the AtACS7 promoter to GA3, ethylene, and ABA,and to darkness and salt. Low-temperature treatment abolishesthe darkness-induced AtACS7 gene expression, but not that ofAtACS4. Each AtACS gene has a unique expression profile duringgrowth and development. It appears that at any developmentalstage or any growth period of Arabidopsis, there is always amember of AtACS multigene family that is actively expressed. Key words: ACC synthase, Arabidopsis, ethylene, gene expression, GUS histochemical staining, reporter, stress treatments 相似文献