[Measurement of several intestinal lysosomal hydrolase activities, through larval development of discoglossus pictus otth, anuran amphibian].

The whole specific activities of 5 lysosomal enzymes (acid phosphatase, N-acetylβ-glucosaminidase,β-glucuronidase, cathepsin and aryl sulphatase) were measured in the guts of Discoglossus tadpoles, before and during metamorphosis.For each hydrolase, the activities show the same variation pattern. They significantly increase at the end of prometamorphosis and the beginning of the climax, while there is histolysis of the first (primary) epithelium of the gut.The measured activities decrease at the end of the climax, while a secondary, enzyme-negative epithelium is developing.The free specific activity of the acid phosphatase was measured in these same guts. It significantly increases at the end of prometamorphosis and the beginning of the climax, during the epithelial histolysis. The total activity increases more slowly than the free one.In the same way, an increase is obtained for the specific activity of the bound (intralysosomal) acid phosphatase.The changes in whole enzymatic activities may result from accelerated synthesis of lysosomal hydrolases due to the primary epitheliocytes, and induced by the simultaneous increase in the plasmatic level of the thyroid hormones. Furthermore the free activity of the acid phosphatase may produce an increased permeability or a breaking of the lysosomal membrane, by the same hormones.