Effect of Hexachlorocyclohexane (HCH), Its Isomers, and Metabolites on Hsp70 Expression in Transgenic Drosophila melanogaster

Expression of hsp70 in the tissues of third-instar larvae of the Bg9(hsp70-lacZ) strain of Drosophila melanogaster after exposure to hexachlorocyclohexane (HCH) (0.5, 1.0, 1.5, 2.0, and 5.0 ng/ml) in the diet was studied by histochemical staining for -galactosidase activity and puffing activity at 9E, 87A, and 87C of the salivary gland polytene chromosome was measured. At concentrations of 2.0 and 5.0 ng;shml, the proventriculus of the foregut, gastric caeca (part or whole), brain ganglia, imaginal discs, salivary glands, midgut, and hindgut of the larvae showed -galactosidase activity. In controls and at dietary concentrations of 0.5 and 1.0 ng/ml, only the proventriculus and part of the salivary gland showed activity, while at 1.5 ng/ml, imaginal discs, the proximal part of brain ganglia, and the whole salivary gland showed positive staining. Among the four isomers of HCH tested, the isomer stimulated the most widespread expression of hsp70 in larval tissues (proventriculus, gastric caeca, part of brain ganglia, imaginal discs, salivary gland, midgut, and hindgut) followed by (proventriculus and salivary gland) and then by the and isomers which produced weak responses in the proventriculus only. Of the metabolites examined in the present study, 2,4,6-trichlorophenol (TCP) evoked the greatest expression of hsp70 compared to the other isomer 2,3,5-TCP and 1,2,3,4-tetrachlorobenzene (TTCB). The puffing pattern in the salivary gland polytene chromosome was similar to the histochemical staining pattern. The present study suggests that there are sites in the larvae vulnerable to HCH, its isomers, and metabolites as evidenced by hsp70 expression.