Sexual dimorphism and developmental changes in hemolymph amylase of Bombyx mori

The amylases in hemolymph of Bombyx mori were assayed by Somogyi-Nelson's reduction method and by starch-iodine reaction after polyacrylamide gel electrophoresis. Total enzyme activities were plotted against stages of development and metamorphosis from the third larval instar to emergence of moth. The maximum amylase activity was shewn at the end of the fifth larval instar, and sexual dimorphism in the activity was defined. When activity was expressed in maltose units/ml hemolymph, females had a greater activity than males in the later half of the fifth instar to the middle stage of pupal life throughout. Different electrophoretic banding patterns for amylases were produced as a function of development and sexuality. Hemolymph amylases were separated into eleven active bands, only the band c was detected in common throughout the developmental stages tested. Band 1 was shown to appear at the middle stage of the fifth instar and disappeared in pupal hemolymph. Bands S-l to S-4 were detected in female larvae of the fifth instar, but not in pupal hemolymph nor in male ones. Band SV was identified characteristically of female pupae. Electrophoretic mobilities of these female-specific amylases coincided with those of female-specific hemclymph proteins thus far recognized by dye-staining.