MATERNAL EFFECT OF MA-1 + ON XANTHINE DEHYDROGENASE OF DROSOPHILA MELANOGASTER, II. XANTHINE DEHYDROGENASE ACTIVITY DURING DEVELOPMENT

Abstract

The mutant ma-1 usually lacks detectable amounts of xanthine dehydrogenase. However, third-instar ma-1 larvae derived from ma-1+ females have between 5 and 10% of the amounts of xanthine dehydrogenase activity found in wild-type larvae; younger larvae have higher relative amounts; eggs have no detectable activity. This indicates that the enzyme activity increases in early maternally affected ma-1 larvae and that the maternal substance is not the enzyme itself. The fact that ry females, which also lack detectable amounts of xanthine dehydrogenase, can be maternally affected ma-1 progeny indicates a type of complementation in vivo between the ry and ma-1 mutants. This phenomenon has its counterpart in the occurrence of complementation in vitro between these 2 nonallelic mutants.