Age-related changes in the activities of respiratory chain complexes and mitochondrial morphology in Drosophila.

Using Drosophila melanogaster, we examined changes in the activities of some of the respiratory enzyme complexes with age. The age-related decreases of enzyme activities were observed especially in complex I. We also examined changes in the ultrastructure of mitochondria in the flight muscles of thoraces. The results indicated that the mitochondrial size varied more widely in aged flies than in young ones, in addition to the slight increase in the average size with age. These changes had already appeared before the survival began to decrease, clearly indicating that the accumulation of such changes seriously damages mitochondrial function.