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Using indirect immunofluorescence visualization techniques we investigated the distribution of RNA polymerase B (or II) and histone H1 at heat shock puff loci in Drosophila melanogaster polytene chromosomes at different times during and after heat shock. After heat treatments of from 5 to 45 min, the heat shock puff displayed intense fluorescence when stained for RNA polymerase B, but relatively little fluorescence when stained for histone H1. Returning heat shocked larvae to room temperature resulted in the appearance of a distinctive pattern of RNA polymerase-associated fluorescence in the heat shock puff at 87C, presumably reflecting events associated with the inactivation and regression of this puff. Large differences observed in the apparent RNA polymerase B content of puffs of similar size suggest that the interaction of RNA polymerase B with chromosomal loci does not depend on simply the state of condensation or decondensation of the chromatin. 相似文献
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Elizabeth Laran José Maria Requena Antonio Jimenez-Ruiz Manuel Carlos Lopez Carlos Alonso 《Chromosoma》1990,99(5):315-320
Multiple interactions of members of the hsp70 family with cellular components have already been described. We present, however, the first evidence that upon heat shock treatment hsp70 molecules interact with specific chromosomal subdivisions of the polytene chromosomes ofDrosophila hydei. After a heat shock treatment of 20 min the protein binds to subdivision 3-58D1 and to the heat shock inducible subdivisions 2-48B3–6 and 2-48C1–2. Hsp70 molecules were also observed in subdivision 3-58D1 during recovery at 25°C but not in subdivisions 2-48B3–6 and 2-48C1–2. Our data suggest that this interaction is stress specific. DNase and RNase experiments suggest, moreover, that the hsp70 molecules bind to RNA from ribonucleoproteins (RNPs) in subdivisions 2-48B3–6 and 2-48C1–2 and to DNA in subdivision 3-58D1. The DNA sequences in subdivision 3-58D1 seem to have the potential to adopt the Z-DNA conformation. 相似文献
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Complementary DNA was made to poly A+ nuclear or polysomal RNA isolated from heat shock tissue culture cells of Drosophila hydei. A number of loci other than the four major heat shock loci are labelled after in situ hybridization of these cDNA preparations, while solution hybridization indicated that only about 10% of the cDNA was specific for heat shocked cells. Removal of the fraction of cDNA which could react with 25° C RNA and subsequent in situ hybridization of heat shock specific cDNA indicated that locus 4–81 B, a major salivary gland heat shock locus, is also active at 25° C in tissue culture cells, while locus 4–85 B is specifically activated by heat shock in tissue culture cells. This latter locus is not seen to be clearly puffed in salivary glands, but was shown to be active in that tissue both by direct autoradiography of salivary gland chromosomes after 3H-uridine labeling and by hybridization of cDNA to chromosomal RNA. 相似文献
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G. H. Vázquez-Nin O. M. Echeverría M. E. Carbajal R. M. Tanguay J. L. Diez S. Fakan 《Chromosoma》1992,102(1):50-59
The Mr 90000 heat shock protein (hsp 90) and one of the Mr 70000 heat shock cognate proteins (hsc 70) were localized by immunoelectron microscopy in salavary gland cells of normal and heat-shocked larvae of Chironomus thummi using polyclonal antibodies raised against Drosophila proteins. Immunoblotting after separation of proteins by gel electrophoresis shows that these antibodies cross-react with the corresponding proteins of Chironomus. Hsp 90 was localized both in the cytoplasm and in the nucleus, where it is associated with intrachromosomal and extrachromosomal ribonucleoprotein (RNP) fibrils, as well as with the peripheral region of compact chromatin. After heat shock the concentration of hsp 90 increases in the nucleus. This increase is prevented by actinomycin D administration during the heat shock. Hsp 90 is associated with the chromatin of puffs repressed by heat shock and with the RNP fibrils of actively transcribing heat shock puffs. Hsc 70 is mainly found in RNP fibrils and in the periphery of compact chromatin. During heat shock the concentration of hsc 70 decreases in the cytoplasm while it becomes more abundant in association with chromatin and intrachromosomal and extrachromosomal RNP fibrils. These results suggest a translocation of the existing protein from the cytoplasm toward the nucleus. They are supported by observations of the effect of heat shock carried out in the presence of actinomycin D.by D.P. Bazett-Jones 相似文献
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O. Hammouda 《Folia microbiologica》1996,41(4):357-362
Purification of DNA-dependent RNA polymerase from exponentially growing cells of the cyanobacteriumSynechococcus sp. is described in cultures grown at normal temperature (39°C) and after heat shock (HS) (47°C). Polyethyleneimine precipitation
followed by chromatography and gel filtration steps results in a 39% yield. The enzyme has a component of molar mass of 43
kDa, designated σ, in addition to the typical procaryotic β’β∝2 and γ. The results suggest thatSynechococcus RNA polymerase is similar to that of cyanobacterial andE. coli RNA polymerases. Electrophoresis of the HS preparation showed that the enzyme has a component of 18 kDa. This suggests the
existence of a functional relationship between this protein and the HS response ofSynechococcus RNA polymerase, probably in salvaging denatured RNA polymerase or helping to regain its native structure. 相似文献
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Small nuclear ribonucleoproteins of Drosophila: identification of U1 RNA-associated proteins and their behavior during heat shock. 总被引:24,自引:6,他引:18 下载免费PDF全文
In Drosophila, two nuclear proteins of approximately 26,000 and 14,000 molecular weight are recognized by a human autoimmune antibody for mammalian ribonucleoprotein (RNP) particles that contain U1 small nuclear RNA. The antibody-selected Drosophila RNP contains, in addition to these two proteins, a single RNA species that has been identified as U1 by hybridization with a cloned Drosophila U1 DNA probe. Small nuclear RNP isolated from human cells under the same conditions as used for Drosophila and selected by the anti-U1 RNP-specific antibody contains eight proteins, two of which are similar in molecular weight to the two Drosophila U1 RNP proteins. Thus, even though the nucleotide sequences of Drosophila and human U1 RNA are about 72% homologous, and the corresponding RNPs are both recognized by the same human autoantibody, Drosophila U1 RNP appears to have a simpler protein complement than its mammalian counterpart. The two Drosophila U1 RNA-associated proteins are synthesized at normal or slightly increased rates during the heat shock response and are incorporated into antibody-recognizable RNP complexes. This raises the possibility that U1 RNP is an indispensable nuclear element for cell survival during heat shock. 相似文献
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Ronald J. Hill Margaret R. Mott Fujiko Watt Theodora Fifis P. Anne Underwood 《Chromosoma》1986,94(6):441-448
An antigen making a major contribution to the immune response to Drosophila melanogaster chromatin resides primarily on a nonhistone charge-class family of proteins of Mr 74,000. Immunofluorescence detects this antigen at interbands, puffs and diffuse bands of D. melanogaster salivary chromosomes isolated without exposure to acid fixatives, and on nucleoplasmic ribonucleoprotein droplets. In the electron microscope, gold labelling reveals the binding of monoclonal antibodies specific for the antigen at chromosomal loci generally bearing putative ribonucleoprotein (RNP) particles. However, the locus 3C 11–12 is remarkable in that it bears putative RNP particles but is virtually unlabelled, suggesting protein specificity at different active loci. 相似文献
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Incubation of 4th instar larvae of Chironomus tentans at elevated temperatures leads in salivary and Malpighian chromosomes to the appearance of 4–5 new puffs. Previously present puffs, particularly Balbiani rings in salivary chromosomes, become drastically reduced. The reactions of region IV-5C and Balbiani ring 1 and 2 in salivary glands are quantitatively analyzed. Statistically significant heat shock effects are observed already after 5 min and reach a maximum between 30 and 60 min. The effective temperature range is small (between 33 to 40 ° C) with an optimum at 37 ° C. Above 40 ° C, i.e., at overheat shock temperatures, heat shock reactions are suppressed. Larvae heat or overheat shocked for 1–7 h or 15–30 min, respectively, survive when returned to normal culturing temperatures. The recovery from heat shock of the puffing pattern occurs in two phases: a fast one (10–20 min) and a slow one (up to 5 h) sometimes separated by a period of backlash. Quenching of overheat shocked larvae does not result in a delayed heat shock reaction. 相似文献
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The heat shock response inLocusta migratoria 总被引:1,自引:0,他引:1
S. Whyard G. R. Wyatt V. K. Walker 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1986,156(6):813-817
Summary
Locusta migratoria adults reared at 27–30°C die after 2 h at 50°C, but they survive this temperature stress if first exposed to 45°C for 0.5 to 4.5 h. Fat bodies from adult females produce a set of at least six specific polypeptides with molecular weights of 81, 73, 68, 42, 28, and 24×103 in reponse to heat shock (39–47°C for 1.5 h). These molecular weights closely match those of the heat shock proteins (hsps) observed inDrosophila, with the possible exception of the 42 kd protein of locusts. The optimal temperature for induction of hsps in locusts is 45°C, which is one of the highest heat shock temperatures reported in metazoans. The correspondence between the optimal temperature for hsp induction and the temperature at which enhanced heat tolerance is acquired (both 45 °C) suggests that the hsps may be associated with thermal protection in these insects.There appears to be no substantial translational control in the locust heat shock response, since other proteins are produced, albeit with some reduction, under heat shock conditions. Vitellogenin synthesis in fat bodies at 45°C is 55% of that observed at 30°C. The high optimal heat shock induction temperature and the continued synthesis of non-heat shock proteins may be adaptive to the locust's natural environment. 相似文献
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Lorena Vega Laura Sevillano Rosa Esteban Tsutomu Fujimura 《Molecular microbiology》2014,93(6):1119-1129
The positive strand 20S RNA narnavirus persistently infects Saccharomyces cerevisiae. The 20S RNA genome has a single gene that encodes the RNA‐dependent RNA polymerase (p91). 20S RNA forms ribonucleoprotein resting complexes (RNPs) with p91 and resides in the cytoplasm. Here we found no host proteins stoichiometrically associated with the RNP by pull‐down experiments. Furthermore, 20S RNA, when expressed from a vector in Escherichia coli, formed RNPs with p91 in the absence of yeast proteins. This interaction required the 3′ cis signal for complex formation. Moreover, when 23S RNA, the genome of another narnavirus, was expressed in E. coli, it also formed RNPs with its RNA polymerase p104. Finally, when both RNAs were expressed in the same E. coli cell, they formed RNPs only with their cognate RNA polymerases. These results altogether indicate that narnaviruses RNPs consist of only the viral genomes and their cognate RNA polymerases. Because the copy number of the RNPs can be induced almost equivalent to those of rRNAs in some yeast strains, the absence of host proteins may alleviate the burden on the host by not sequestering proteins into the RNPs. It may also contribute to the persistent infection of narnaviruses by decreasing their visibility. 相似文献
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M E Samuels D Bopp R A Colvin R F Roscigno M A Garcia-Blanco P Schedl 《Molecular and cellular biology》1994,14(7):4975-4990
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