PROPICONAZOLE AND DIETARY-COMPONENTS AS SPECIFIC INDUCERS OF GLUTATHIONE S-TRANSFERASES IN ORTHOSIA-GOTHICA

Six major glutathione S-transferase (GST) subunits (subunits 1-6), belonging to two different GST classes (GST1 and GST2), were purified by glutathione-Sepharose affinity chromatography and reverse-phase high-performance liquid chromatography (HPLC) from the gut-free soft tissue cytosol of last instar Orthosia gothica fed a bean diet (large white kidney beans) to which propiconazole (250 ppm) had been added for 2 days. Subunit 2, which belonged to O. gothica GST1, was also present in the cytosol of the larvae given the bean diet without propiconazole, apple leaves (Malus domestica cult.), or willow leaves (Salix caprea). However, the amount of subunit 2 relative to the other subunits varied with the diet and pesticide treatment. Subunits 1 and 3-6 all belonged to O. gothica GST2 and all had the same M(r) and pI. Subunits 3 and 6 were not present in the larvae given apple or willow leaves only, and the amount of subunit 3 was significantly higher than the other GST2 subunits in the larvae which had been given propiconazole. The cytosolic GST activity toward 1-chloro-2,4-dinitrobenzene, 1,2-dichloro-4-nitrobenzene, and cumene hydroperoxide did not change with diet and fungicide treatment. (C) 1995 Academic Press, Inc.