The distribution of phosphomonoesterases in the digestive gut of Porcellio laevis latreille (Porcellionidae, Isopoda)

Abstract

1. 1. The distribution of phosphomonoesterases was examined, by histochemical and biochemical means, in the hepatopancreas, digestive gut and the gonads of the tenth instar Porcellio laevis. 2. 2. The digestive gut and the hepatopancreas contained the bulk of the phosphomonoesterase activities (63·45 per cent of the total in the case of acid phosphatase, and 71 per cent of the total for alkaline phosphatase), although hepatopancreas was comparatively richer (39·05 per cent of the total) in acid phosphatase, while the digestive gut was richer (41 per cent of the total) in alkaline phosphatase. 3. 3. More than 50 per cent of the phosphomonoesterase activity in the hepatopancreatic tissue was contained in nuclei, while mitochondria and microsomes showed 26–28 and 5 per cent activities, respectively. 4. 4. In the digestive gut, 42–44 per cent phosphatase activity was located in the soluble fraction, 8 per cent in microsomes, 30–35 per cent in mitochondria and 25–30 per cent in nuclei. 5. 5. Acid phosphatase activity was the highest (37·14 per cent of the total) in the hindgut, while alkaline phosphatase was most prominent (44·64 per cent of the total) in the proctodael “midgut”. 6. 6. Both gonadal and the exoskeletal tissues appeared to be the poorest sources of phosphomonoesterases.