Divergent effects of hyperosmolality on stress-response (heat shock) protein expression in cultured human tumor cells: an immunocytochemical study

Exposing cells to adverse conditions usually elicits expression of stress-response (heat shock) proteins (srp). Here we show that hyperosmolar growth conditions do not uniformly affect srp expression in MCF-7 and HeLa S3 cells, derived from carcinoma of the breast and cervix, respectively. Thus, whereas srp 27 expression was increased in MCF-7, but not in HeLa S3, the opposite was the case with srp 72. On the other hand, hyperosmolality did not induce B-crystallin or ubiquitin in either cell line. These findings show that srp expression by the human tumor cells studied is non-coordinate, suggesting that each srp is independently modulated.     

Synthesis of a ubiquitously present new HSP60 family protein is enhanced by heat shock only in the Malpighian tubules ofDrosophila

A homologue of the chaperonin protein of the HSP60 family has not been shown so far inDrosophila. Using an antibody specific to HSP60 family protein in Western blotting and immunocytochemistry, we showed that a 64-kDa polypeptide, homologous to the HSP60, is constitutively present in all tissues ofDrosophila melanogaster throughout the life cycle from the freshly laid egg to all embryonic, larval and adult stages. A 64-kDa polypeptide reacting with the same antibody in Western blots is present in all species ofDrosophila examined. Using Western blotting in conjunction with³⁵S-methionine labeling of newly synthesized proteins and immuno-precipitation of the labeled proteins with HSP60-specific antibody, it was shown that synthesis of the 64-kDa homologue of HSP60 is appreciably increased by heat shock only in the Malpighian tubules, which are already known to lack the common HSPs.     

Mitochondrial distribution and inheritance

Mechanisms mediating the inheritance of mitochondria are poorly understood, but recent studies with the yeastsSaccharomyces cerevisiae andSchizosaccharomyces pombe have begun to identify components that facilitate this essential process. These components have been identified through the analysis of conditional yeast mutants that display aberrant mitochondrial distribution at restrictive conditions. The analysis of these mutants has uncovered several novel proteins that are localized either to cytoskeletal structures or to the mitochondria themselves. Many mitochondrial inheritance mutants also show altered mitochondrial morphology and defects in maintenance of the mitochondrial genome. Although some inheritance components and mechanisms appear to function specifically in certain types of cells, other conserved proteins are likely to mediate mitochondrial behavior in all eukaryotic cells.     

二聚体参与真核基因转录调节研究的新进展

本文对蛋白二聚体参与转录调节进行了综述，并较详细地阐述了Ｂ－Ｚｉｐ和Ｂ－ＨＬＨ蛋白的结构特点及功能。     

被子植物雌雄配子及其表膜特异蛋白研究进展

近年来．被子植物雌雄配子的细胞学与生物化学研究取得了一系列重要进展．包括精卵细胞分离纯化、活力保持与检测技术的建立、形态的构观察、生化特性分析及人工体外融合成功，等等．这些进展为创建体外受精操作系统及探讨受精识别机理提供了可能性．被子植物双受精过程存在多位点识别．有关配子水平识别的研究刚刚起步，主要是通过不同途径寻找雌雄配子表膜特异蛋白．其中质膜的纯度与数量问题亟待解决．     

An interspecies conserved antigen ofPlasmodium falciparum containing clusters of asparagine residues

An interspecies conservedPlasmodium asparagine rich antigen, designated as ARK26, was isolated by immunoscreeningP. falciparum genomic DNA expression library with mouse convalescent anti-P. yeolii serum. Partial DNA sequence analysis reveals that ARK26 contains clusters of asparagines and no randomly repeated amino acid sequence motifs are observed. A 65×10³ GST fusion protein is expressed by recombinant plasmid PGEX-5X-1 (ARK26) inE. coli C strain ABLE-K. Computer programs predict that two asparagine rich regions are among the possible antigenic epitopes of p37 encoded by ARK26. Interestingly, the sequence of ARK26 displays significant similarity to yeast and several other species’ mitochondrial genes, and its possible function is discussed. Supported by a fellowship offered by International Center for Genetic Engineering & Biotechnology(ICGEB) Ma Donghui: born in 1969, Graduate student     

Involvement of heterotrimeric G protein in signal transduction of extracellular calmodulin in regulatingrbcS expression

The role of heterotrimeric G protein in signal transduction pathway of extracellular calmodulin in regulating rbcS expression was examined in suspension-cultured cells of transgenic tobacco. Pharmalogical experiments indicated that G protein agonist cholera toxin enhanced rbcS expression and heterotrimeric G protein antagonist pertussis toxin inhibited rbcS expression in transgenic tobacco cells. Pertussis toxin also inhibited the enhancement effect caused by exogenous purified calmodulin on rbcS expression, whereas cholera toxin completely reversed the inhibitory effects caused by anti-calmodulin serum on rbcS expression. The right side-out vesicles from tobacco cell membrane were purified, which contained all of substrates for fluometric assay of GTPase activity. Exogenous purified calmodulin, when adding directly to the medium of plasma membrane vesicles, significantly activated GTPase activity in the right side-out plasma membrane vesicles, and this increase in GTPase activity was completely inhibited both by heterotrimeric G proteins antagonist pertussis toxin and nonhy-drolyzable GTP analogs GMP-PCP. These results provided the evidence that heterotrimeric G proteins may be involved in signal transduction pathways of extracellular calmodulin to regulate rbcS gene expression.     

草履虫类核纤层蛋白的初步研究

本文以DGD包埋去包埋技术对草履虫的核纤层通过透射电镜和免疫荧光、分子杂交等技术进行了观察。结果显示,在核周存在由10nm纤维组成的核纤层;免疫荧光结果表明,在核周呈阳性反应,并在其表皮、口器等部位呈交叉的阳性反应;蛋白分子杂交的反应带在68kD处呈阳性反应。     

Rayleigh light scattering and its applications to biochemical analysis

The recent applications of light scattering technique in biochemical analysis have been reviewed. The mechanic theories of resonance light scattering and Rayleigh light scattering (RLS), the relationships and differences between them, their applications and the interference factors in biochemistry analysis have been covered. By contrasting Rayleigh light scattering with double scattering and anti-scattering, the advantages of RLS have been pointed out. Finally, some prospects for the future application of this technique have been given.     

一个新C2H2型锌指蛋白的功能的初步研究

通过筛选人18周胎脑cDNA文库,得到一条编码332AA的全长新基因,生物信息学研究表明,该蛋白质序列有2个C2H2型锌指结构,其中1个锌指结构有RNA－binding蛋白特异锌指的特征,虽然同源比较发现与多种蛋白质精氨酸N端转甲基酶（protein arginine N-methyltransferase) 有一定的同源性,但新锌指蛋白不含转甲基酶的活性功能区域,属功能未知的基因,利用芯片研究功能未知基因的表达是一种较好的手段,通过代谢增强剂PMA（phorbol myristae acetate)刺激培养的血管内皮细胞,观察细胞受激活后新锌指蛋白基因的表达变化,结果表明新基因表达量提高了11倍以上,证实新基因属内皮细胞的极早期应答基因（Immediate early response gene,ERG)。