Intracellular distribution of β-glucuronidase activity during metamorphosis of the housefly, Musca domestica L.

Abstract

β-Glucuronidase and glucuronyl transferase activities were determined in various stages of third instar larvae and pupae of M. domestica. Most of the β-glucuronidase activity was found in the particulate fractions: lysosomes and microsomes. No enzyme activity could be detected in the early third instar larvae. It increased by 10-fold in the pupal stage and has a pH optimum of 4.0. The enzyme activity in the soluble fraction increased from 30% in the late larval stage to 45% in the late pupal stage. About 56% of lysosomal β-glucuronidase activity exhibited structure-linked latency. The free activity of the lysosomal fractions increased from 44% in the late larval stage to over 64%, in the late pupal stage. Glucuronyl transferase activity was low at all times during metamorphosis. The rapid rate of β-glucuronidase synthesis during pupal and late pupal stages and the increase in the lysosomal free activity has been discussed in relation to the cellular dissolution and tissue reconstitution during metamorphosis.