Biochemical processes during the biogenesis of flight muscle mitochondria in the moth Heliothis virescens (F.) (Lepidoptera: Noctuidae)

Abstract

The development of flight muscle mitochondria is described for male Heliothis virescens (F.) by changes in respiratory and electron transport enzyme activities and incorporation of [superscript 14]C-1-leucine in vivo into mitochondrial protein. Synthesis of proteins for the mitochondria began early in imaginal metamorphosis and reached a maximum before increases in enzymatic activity were measurable. ?æ-Glycerophosphate oxidase activity reached a maximum two days prior to adult emergence while succinate oxidase activity reached a maximum on the day of adult emergence. No post emergence maturation was observed. Electron transport enzyme activity was estimated as succinate cytochrome c reductase and cytochrome c oxidase activities. Synchronous development of these enzymes and succinate oxidase was observed. Difficulty was experienced in measuring oxidative phosphorylation and respiratory control. The influence of cycloheximide, choramphenicol, aminotriazole, and acriflavine upon morphological indicators of development as well as respiratory enzyme activity was determined. While inhibitors of gene translation (cycloheximide, chloramphenicol) blocked the initiation of development, the emergence of moths capable of flight was susceptible to all compounds tested. Respiratory activities proved resistant to chloramphenicol and aminotriazole. Cytochrome c oxidase was drastically reduced by acriflavine treatment. The role of the brain upon flight muscle mitochondrial development was tested by inducing brainless pupae to initiate development with ecdysterone treatment. When respiratory capacities of thoracic mitochondria from treated insects were measured, succinate cytochrome c reductase was found to be more fully induced than cytochrome c oxidase. These results are interpreted as providing insights into control mechanisms for mitochondrial biogenesis and diapause in H. virescens.