Changes in lipid and protein synthesis during spermatozoan development and thoracic tissue maturation inDrosophila...

The synthesis of protein and lipid was studied in the testis and thoracic tissues ofDrosophila hydei by radioisotope incorporation. The formation and accumulation of late stage gametes in the testes during maturation was accompanied by more than 4-fold increases in both lipid and protein synthesis rates. Though there was an 8-fold increase in the rate of protein synthesis during thoracic tissue maturation, the rate of lipid synthesis little more than doubled. By comparison the rates of protein synthesis were high in mature testis and thoracic tissues, whereas the rate of lipid synthesis was high in the mature testis but low in both immature and mature thoracic tissues.Label incorporation from pyruvate and L-alanine into protein in thoracic tissue appeared to be highly dependent on Krebs cycle activity, whereas pyruvate and L-alanine label incorporation into protein in the testis was primarily from L-alanine and its derivatives. Both pyruvate and L-alanine were decarboxylated prior to label incorporation into lipid in the testis and thoracic tissue.