Examination of heat shock gene expression in nerve cord isolated from heat-stressed American cockroach, Periplaneta americana

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Abstract
Exposure of adult female cockroaches to temperatures ranging from 37 to 42%.ETA. induced the synthesis of a set of heat shock proteins (HSPs) in isolated nerve cord. The major HSPs have molecular masses of 83 000, 70 000, 68 000, and 28 000 daltons. Enhanced synthesis of these HSPs was detectable after 15 min of heat shock and approached maximum levels after 2 h. In cockroaches exposed to 43.degree.C for 1 h and then returned to 22.degree.C, a normal pattern of protein synthesis was established within 3-5 h. Northern hybridization analysis using Drosophila HSP 70 and HSP 83 genomic clones revealed the accumulation of 2.6 and 3.1 kilobases mRNA, respectively, in total RNA derived from heat-shocked tissue. A rapid decay of these mRNAs was observed in cockroach nerve cord during recovery at 22.degree.C following a 1-h heat shock at 42.degree.C. The decrease in HSP synthesis and HSP mRNA levels during recovery may be due to a decrease in mRNA stability as well sa transcription.