ENDOCRINE CONTROL OF PROTEIN METABOLISM AS RELATED TO REPRODUCTION IN FLESHFLY SARCOPHAGA BULLATA

Females of the fly Sarcophaga bullata require a dietary source of proteins or amino acids to support egg maturation. At emergence the haemolymph protein levels were low and dropped still farther in sugar-fed females during the next 10 days. However, after meat was added to the diet the haemolymph protein concentrations rose and yolk was deposited in the eggs of these females. Ovariectomized (OV-) females had high haemolymph protein levels and large corpora allata. Allatectomy (CA-) after emergence prevented yolk deposition in 30 per cent of the females. Those CA- females which did not deposit yolk had low haemolymph protein levels, whereas those which did deposit yolk had high concentrations. All females CA- at pupation matured eggs and had high haemolymph protein levels. Haemolymph protein concentrations of females after the neurosecretory cells of the pars intercerebralis were removed (NSC-) were similar to those of unoperated females of the same age. The haemolymph of sugar-fed females and that of all males contained six proteins as shown immunologically. Meat-fed, egg-maturing females contained these six proteins plus a seventh protein (the 'female' protein). All seven proteins were present in the haemolymph of OV- and NSC- females as well as in those CA- females which deposited yolk. Of the CA- females which did not deposit yolk, the 'female' protein was absent in 64 per cent of the cases, but this protein was present in low concentration in the remaining 36 per cent. It is concluded that in Sarcophaga bullata the allatum hormone may be involved in the regulation of protein metabolism and that neurosecretion from the pars intercerebralis serves as a gonadotropin. © 1969.