CITRIC-ACID CYCLE - A MAINSTREAM METABOLIC PATHWAY INFLUENCING LIFE-SPAN IN DROSOPHILA-MELANOGASTER

The role of the citric acid cycle enzyme NADP-dependent isocitrate deh ydrogenase (IDH-NADP) and its allele product variants in resisting the oxidative agent paraquat, was analyzed among descendants of reciproca l crosses between fast developmental time short-lived individuals (F-) and slow developmental time long-lived ones (S+), in Drosophila melan ogaster. Taking preadult developmental time into account, the data sug gested that IDH-NADP differences in enzymatic activity between electro phoretically fast and slow allele product variants could play an impor tant role in paraquat resistance and longevity, because individuals wi th slow developmental time bearing the fast electrophoretic variant of IDH-NADP (''fast'' allele) were the most resistant. The fast electrop horetic variant df this enzyme is known to be the most active one and its activity is related to increased reduction of NADP to NADPH. This process could be very important for an effective balance between sever al pathways that use NADPH as precursor molecules and the oxidative st ress defense system that uses it as an oxygen free radical reductor. W e also reported a strong maternal effect on these traits, because surv ivors of a paraquat bioassay carrying cytoplasm inherited from slow de velopmental long-lived females (S+ cytoplasm) showed the highest frequ ency of the fast electrophoretical variant of IDH-NADP. Copyright (C) 1996 Elsevier Science Inc.