Spectrophotometric determinations were made of TPN-isocitiric dehydrogenase activity in the mitochondria and soluble fractions of one susceptible and two insecticide-resistant strains of larvae of Aedes aegypti(L.). It was found that the enzyme activity of the soluble fraction was approximately the same in all three strains, hut mitochondria showed appreciable differences in activity, The soluble fraction contained from 10 to 40 times the activity of mitochondria depending upon the strain. DDT added at a concentration of 1,1X104 M inhibited the TPN-isocitric dehydrogenase activity in the mitochondria of the Sand DDT-R strains, whereas it increased the enzyme 1'1'0111 the corresponding fraction in the DL-R strain. The saIne inseeticide increased the soluble TPN-iscitric dehydrogenase of the S and DDT-R strains and inhibited it in the DL-R strain. Dieldrin at a concentration of 1.1X 10-4 M behaved in a manner similar to DDT on the TPN-isocitric dehydrogenases of the DL-R strain by increasing the mitochondrial enzyme and inhibiting the soluble enzyme. The effects of DDT and dieldrin, and the possibility of biochemical differentiation of TPN-isocitric dehydrogenases derived form the two cellular locations are discussed.
Document Type: Research Article
Publication date: June 1, 1961
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