The sexual difference in degradation of sulfur amino acids in pupae and adults of the silkworm, Bombyx mori

The degradation of sulfur amino acids in pupae and adults of the silkworm, Bombyx mori, was investigated. The rate of 14CO2 production from DL-cystine-1-14C varied during pupal development and also between male and female significantly; in the male the 14CO2 production increased markedly according to pupal development, whereas in the female it was kept at a low level until emergence, then increased slightly. Total sulfur in meconium of the female was less than a half the quantity of that of the male. However, in the ovary-ectomyzed female the amount of total sulfur in meconium and the rate of 14CO2 production were increased, almost similar to the case of the male. It was also confirmed that the 14C of DL-cystine-1-14C was incorporated efficiently into egg protein at the end of pupal stage. These results indicated that the rate of degradation of sulfur amino acids in the pupal stage was much active in male than in female. Such a sexual difference is considered to be related closely to the formation of egg, especially egg-shell. (auth.)