Genetic variation in the expression of the six hsp genes in the presence of heat shock in Drosophila melanogaster.

Genetic variation in total mRNA level of the six hsp genes (hsp22, hsp23, hsp26, hsp27, hsp70 and hsp82) in the presence of heat shock was investigated by using seventy-four second- and seventy third-chromosome lines of Drosophila melanogaster which have the same genetic background derived from a highly inbred stock. There was significant variation in all the six hsp genes for both the second- and third-chromosome lines except for the hsp22 gene of the third-chromosome lines. Although all the structural genes of the heat shock proteins are localized on the third chromosome, the estimates of genetic variance for the second-chromosome lines were larger than those for the third-chromosome lines. Highly significant correlations between total mRNA level of the different hsp genes in all the combinations of the six hsp genes using the second-chromosome lines were found, but some of correlations for the third-chromosome lines were not significant. These results suggest that some second chromosome variants have similar effects on the expression of the different genes.