Non-Identity of Triosephosphate Dehydrogenase of Adult Male and Nymph Development Stages of Triatoma infestans

Abstract

WHILE studying the mode of action of 2,2-bis-(p-chlorophenyl)-1,1,1-trichloroethane (DDT) on Triatoma infestans it was found that an in vivo dose of both DDT and 2,2-bis-(p-chlorophenyl)-1,1-dichloro-ethylene (DDE) which inhibited triosephosphate dehydrogenase derived from male adult specimens of T. infestans was without effect on the enzyme derived from nymph specimens (our unpublished observations). This different behaviour of triosephosphate dehydrogenase derived from two different stages in development of the same insect has been also observed in vitro. Extracts for enzymatic assay were prepared as follows. The thoraces and legs of male or nymph specimens were ground in a mortar with 0.15 M potassium chloride and extracted during 60 min. at 2°; the resulting brei was filtered through cheese-cloth to remove pieces of cuticle and the filtrate centrifuged at 20,000g for 60 min. at 2°; the supernatant fluid was finally filtered through Whatman No. 1 paper and used as such as a source of enzyme. Triosephosphate dehydrogenase was assayed as described elsewhere¹.