Biochemical and structural variations in the flight muscle mitochondria of ageing blowflies, Calliphora erythrocephala.

Biochemical investigations with isolated blowfly flight muscle mitochondria show that uncoupling of oxidation and phosphorylation increases with increasing age of the adult fly. Of the two principal substrates used (i.e. a-glycerophosphate and pyruvate), uncoupling is most marked when a-glycerophosphate is used as substrate. Although age-related changes in the structure of the thoracic flight muscle are observed by electron-microscope studies, no obvious degenerative changes take place in either the mitochondrial structure or the myofibrils of old flies. Labelling experiments with [H]leucine indicate that uncoupling is mainly due to the lack of repair and replacement of mitochondrial proteins. These experiments also show that mitochondria] protein synthesis is important in the maturation of young flies, that is, those between o and 4 days old, but is insignificant in the further increase in mitochondrial size observed in older flies, where mitochondrial fusion appears to be more important.