The effects of temperature shock on transcription and replication in Rhynchosciara americana (Diptera: Sciaridae).
The chromosomal response to temperature shock in Rhynchosciara americana is similar to that observed in other Diptera. After a 33 degrees C/90 min or a 36 degrees C/30 min shock the reaction for RNA polymerase II (RpII) is enhanced at five loci. The most prominent of these was identified by in situ hybridization as the site of the hsp70 gene. At 33 degrees C, an accumulation of heat shock factor (HSF) and an increase in the level of RpII was observed at some heat shock loci after 5 min and reached a maximum after 15 min at most loci. The pattern of accumulation of HSF and RpII at individual heat shock loci was similar and their increases were generally coordinated among the loci. RpII gradually decreased at sites active prior to shock, the rate of decrease varying with the site. The B2 DNA puff retained RpII for a significant length of time while the histone locus still contained RpII after a shock of 90 min. With a 36 degrees C/30 min shock, the size of the heat shock puffs and the intensities of HSF and RpII peaked at 1-4 h post stress. The level of HSF declined rapidly after 1 h while the level of RpII remained high for an additional 4 h. The reaction of the DNA puffs to heat shock varied. Usually they did not regress completely and retained traces of RpII. BrdU incorporation continued at both amplifying and non-amplifying bands after shock but on average it appeared depressed for about 24 h post stress.
Stocker
Ann Jacob
AJ
Departmento de Biologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 277, Cidade Universitária, CEP 05508-090, São Paulo, Brazil.
Madalena
Christiane R G
CR
Gorab
Eduardo
E
D000818:Animals; D004261:DNA Replication / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004175:Diptera / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029721:Drosophila Proteins / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D000076249:Heat Shock Transcription Factors; D018869:Heat-Shock Response / Q000235:genetics*; D012319:RNA Polymerase II / Q000378:metabolism; D013696:Temperature; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018840:HSP70 Heat-Shock Proteins; D000076249:Heat Shock Transcription Factors; C053134:Hsf protein, Drosophila; D014157:Transcription Factors; D012319:RNA Polymerase II