Deficiency of xanthine dehydrogenase activity in the oq oily mutant of the silkworm, Bombyx mori

Abstract

To investigate the mechanism of gene expression responsible for the oily character of the silkworm, Bombyx mori, xanthine dehydrogenase activity and the amount of its metabolites in the oq oily mutant larvae were determined. The enzyme activity in the fat body of the mutant was markedly lower than normal. Uric acid was not present in the feces and the integument of the mutant, whereas a large amount of xanthine accumulated in the mutant feces. Thus, the oq mutant is enzymatically deficient. A previous report, which described that a locus (og) controlled xanthine dehydrogenase activity, and the discovery of this new mutant demonstrated that the synthesis of this enzyme in the silkworm is controlled by at least two different loci, og (9-7.2) and oq (12-26.3).