Activating protein factor binds in vitro to upstream control sequences in heat shock gene chromatin

DNA sequences, important for the control of Drosophila heat shock gene expression, are packaged in chromatin in a nuclease hypersensitive configuration. Recently, two protein-binding (exonuclease-resistant) sites which cover the TATA box sequence and an upstream control element were shown to occur in vivo amidst the 5' terminal hypersensitive regions of several heat shock genes. Protein-binding at the TATA box is independent of heat shock, but the binding at the upstream element is heat shock dependent, and it was proposed that a heat shock activator protein, HAP, positively regulates the genes. Here, I report the detection of HAP activity in heat shocked cell extracts by reconstituting specific binding to hsp82 gene chromatin in vitro. Inhibition of the binding by free DNA from the 5' region of heat shock genes implies a coordinate regulation of the gene family through HAP interaction with the upstream heat shock consensus sequence. Furthermore, the special ease of induction of the hsp82 gene over other heat shock genes can be explained in molecular terms by the higher affinity of HAP for the hsp82 binding site, which contains a 28 base sequence with almost perfect dyad symmetry, GAAGCCTCTAGAAG/TTTCTAGAGACTTC.     

Apoptosis in suspension culture of tobacco cells induced by heat shock

The induction of apoptosis in suspension culture of tobacco cells by heat shock is reported for the first time. Heat treatment (48℃ for 4 h) of tobacco cells led to the appearance of typical hallmarks of apoptosis. It was demonstrated by DNA laddering analysis that the cells treated with heat shock at 48℃ for 4 h had a serious degradation of nuclear DNA into multi-nu-cleosomal sizes, suggesting that heat shock activated endogenous nuclease which led to DNA cleavage at the linkage sites between the nucleosomes, but ladders were very faint for DNA from 2 and 9 h heat-treated cells. The terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labelling (TUNEL) detection also showed that most of these treated cells (48℃ for 4 h) displayed positive reactions, indicating a serious DNA 3'-OH cleavage in their nuclei. Moreover, some other cytological changes in apoptotic cells, such as cell shrinkage, chromatin aggregation, nucleus collapse, have also been observed by 4', 6'-diamidino-2-phenyl-indole (DAPI) staining.     

热击对水稻(O.sativaL.)叶绿素a,b及POR同功酶的效应

研究热击对水稻苗期生理生化的影响,结果表明,在热击条件下（３５℃,４０℃,４５℃各半个小时）水稻苗期生长出现显著差异,特别是经过热击和非热击条件对比更加明显。此外,经热击处理后,水稻苗期叶绿素的含量随温度的不同而呈现一定的变化规律,并且经聚丙烯酰胺凝胶电泳发现,热击对过氧化物酶同工酶产生显著影响。     

热休克蛋白的研究进展

在不利的环境中,各种有机体都有其共同对应的分子反应,即正常基因的表达抑制和一组特殊基因——热休克基因的激活和表达,导致热休克蛋白的大量产生,热休克蛋白主要作为分子伴侣而参与蛋白质的折叠、转运及组装等过程,能恢复或加速清除细胞内已变性的蛋白质而稳定细胞结构,细胞产生热耐受。随着对热休克蛋白研究的不断深入,在生物工程和医学等方面的应用前景十分广阔。     

肝大部切除前后热休克处理对热休克蛋白、酸性磷酸酶和碱性磷酸酶活性影响的分析

综合了磷酸酶的原位复性电泳、体视学分析、比色分析等方法分析①切除大白鼠大部分肝后的肝再生期间,②热休克处理大白鼠（４６℃、３０ｍｉｎ）恢复８ｈ,再切除大部分肝后的肝再生期间,③切除大部分肝恢复４ｈ,再热休克处理（４６℃、３０ｍｉｎ）后的肝再生期间热休克蛋白（ＨＳＣ７０／ＨＳＰ６８）、酸性磷酸酶（ＡＣＰ）和碱性磷酸酶（ＡＫＰ）动态变化的资料,从６个方面比较分析了ＨＳＣ７０／ＨＳＰ６８,ＡＣＰ和ＡＫＰ在肝再生中的相互关系及对肝再生的可能作用     

俄罗斯鲟雌核发育诱导及其后代的微卫星分析

通过冷休克和热休克法诱导2组俄罗斯鲟Acipenser gueldenstaedtii雌核发育,分别获得俄罗斯鲟的冷休克雌核发育组M1和热休克雌核发育组M2。利用6对具有高多态性的微卫星分子标记,分别对雌核发育系M1中的20尾鱼苗、M2中的40尾鱼苗、双亲及对照组20尾鱼苗基因组进行PCR扩增,并对结果进行基因型分析。分别得到2个雌核发育家系的期望杂合度(He)、等位基因数(A)和等位基因频率(P)。结果表明:冷休克雌核发育组的平均期望杂合度为0.591,平均等位基因数为6.0,等位基因频率为0.010～0.708;热休克雌核发育组的平均期望杂合度为0.687,平均等位基因数为5.5,等位基因频率为0.006～0.774。以父本特异微卫星条带作为诊断性标记,对雌核发育后代进行鉴定,结果发现在冷休克组和热休克组中分别存在40%和27.5%的杂交后代,此结果与表型鉴定结果相一致。另外,与母本基因型相比较,发现在冷休克组和热休克组中分别存在10%和15%的单倍体个体。只在热休克组中发现了完全的雌核发育后代,占总数的22.5%。冷休克和热休克雌核发育家系中除了单倍体后代,杂交后代和完全雌核发育后代外,还发现了不同程度的基因重组后代。     

Heat-shock induced proteins present in the cell nucleus of Chironomus tentans salivary gland.

The heat shock (HS) system has been largely studied in Drosophila but the molecular mechanisms responsible for the induction of the heat shock genes as well as the function(s) and the intracellular localisation of the induced proteins is still unknown. It has previously been shown that the HS puff induction is accompanied by a local increase of nuclear nonhistone proteins (NHP) but the nature of most of the proteins accumulating is unknown. We have investigated the effects of a heat shock on Chironomus tentans salivary glands, a system where it is possible to study constituents in various subcellular or intranuclear regions including individual puffs, by microdissection. We report here evidence that at least two of the polypeptides synthesised in response to the heat shock migrate to the nucleus. Furthermore, these two proteins appear to have a broad intranuclear distribution, as shown by their presence in the various microdissected nuclear fractions.     

Cyclic AMP response element binding protein (CREB) participates in the heat-inducible expression of humanhsp90β gene

Human heat shock protein 90b gene ( hsp90b ) is a constitutively expressed heat shock gene existing in most of cell types tested that can be further induced by heat shock. Chloramphenical acetyl transferase (CAT) reporter plasmids driven by different regulatory fragments of hsp90b gene were constructed and transfected into Jurkat cells to explore the role of a cAMP response element (CRE) in the upstream of the gene. Results show that, in comparison with the wild type construct, a severe reduction (~2/3) in the increased folds of promoter activity induced by heat shock at 42℃ for 1 h was observed in a construct with CRE-containing fragment (-173/-91bp) deleted. Electrophoretic mobility shift assays (EMSA) showed that phosphorylated CRE-binding protein (CREB) in the nuclear extract of heat shocked Jurkat cells is specifically bound to the fragment. Additionally, both of the phosphorylation on CREB and the activity of protein kinase A (PKA) were found in Jurkat cells to be enhanced with extending time of heat shock treatment. Our results indicate that in addition to the intronic HSE/HSF pathway, phosphorylated CREB also participates in the heat shock induced expression of human hsp90b gene via its interaction with CRE which may be regulated by PKA-sig- naling pathway.     

黄颡鱼三倍体人工诱导方法的比较研究

应用热休克、冷休克、6-DMAP和CB处理黄颡鱼受精卵,探讨诱导三倍体的适宜方法.4种方法均能诱导黄颡鱼受精卵形成三倍体胚胎.受精卵经热休克处理（受精后第8min,40℃处理2min）,诱导率为93.3%,孵化率为78.6%;冷休克法（受精后第3min,4℃处理15min）诱导率为63.3%,孵化率为82.3%;受精卵经6-DMAP和CB处理得到的诱导率较低,分别为26.7%和10.0%.综合考虑,热休克法及冷休克法为诱导黄颡鱼三倍体的适宜方法.     

热休克后小鼠血红蛋白和血清蛋白的初步研究

本文采用人工气候室模拟自然热环境对小白鼠进行急性热暴露实验．测定热休克后不同时程小白鼠血中血红蛋白含量和血清中总蛋白含量变化，同时对血清蛋白进行电泳分析．结果表明，热休克后不同时程血红蛋白含量和血清总蛋白含量出现规律性改变，血清蛋白电泳图谱未见明显改变．作者对实验结果的意义做了分析．     

Hsp104 is a highly conserved protein with two essential nucleotide-binding sites

Most eukaryotic cells produce proteins with relative molecular masses in the range of 100,000 to 110,000 after exposure to high temperatures. These proteins have been studied only in yeast and mammalian cells. In Saccharomyces cerevisiae, heat-shock protein hsp104 is vital for tolerance to heat, ethanol and other stresses. The mammalian hsp110 protein is nucleolar and redistributes with growth state, nutritional conditions and heat shock. The relationships between hsp110, hsp104 and the high molecular mass heat-shock proteins of other organisms were unknown. We report here that hsp104 is a member of the highly conserved ClpA/ClpB protein family first identified in Escherichia coli and that additional heat-inducible members of this family are present in Schizosaccharomyces pombe and in mammals. Mutagenesis of two putative nucleotide-binding sites in hsp104 indicates that both are essential for function in thermotolerance.     

玉米幼苗热激诱导抗冷性过程中钙的效应

 玉米幼苗在冷胁迫前经过热激处理或CaCl₂浸种后再热激处理,其存活率,抗氧化酶GR的活性、可溶性蛋白质中热稳定蛋白质和游离脯氨酸的含量在的冷胁迫中均发生了变化,发现热激处理幼苗的这些参数高于对照,而最高的是CaCl₂浸种后再热激处理的,表明热激能提高玉米幼苗的抗冷性,而Ca²⁺对上述热激处理有加强作用.     

热休克诱导三倍体黄鳝的研究

采用热休克诱导方法研究了促使第二极体保留诱发三倍体黄鳝的最佳条件．在卵受精后５－６ｍｉｎ，采用４０．５℃热水处理３．５ｍｉｎ，不但能导致较高的三倍化率，而且胚胎存活率相当高，表明热休克是诱导多倍化的有效方法，需用设备简单，易于推广     

真核生物的热击反应及转录调控的研究现状

真核生物受热击及其他应激作用后能诱导产生ＨＳＰ。ＨＳＰ在生物体内起着重要的生理功能。研究热击反应有助于搞清植物基因表达调控的机理，这也是科学家们近几年来研究的热点。随着植物基因工程技术的完善和发展，这一研究进展很快。ＨＳＥ、ＨＳＦ和ＨＳＰ在热击基因转录和调控过程中起着非常重要的作用。