Patterns of N-acetyl-beta-glucosaminidase isoenzymes in the epidermis and hepatopancreas and induction of N-acetyl-beta-glucosaminidase activity by 20-hydroxyecdysone in the fiddler crab, Uca pugilator

A new staining method for detection of N-acetyl-beta-glucosaminidase on den aturing SDS polyacrylamide gels was developed. The isoenzyme pattern of N-a cetyl-beta-glucosaminidase in the epidermis of the fiddler crab, Uca pugila tor, is different from that in the hepatopancreas. Two isoforms of N-acetyl -beta-glucosaminidase, with molecular weights of 89 and 45.6 kDa, are prese nt in the hepatopancreas while there is only one form of N-acetyl-beta-gluc osaminidase, 89 kDa, in the epidermis. No sexual dimorphism was found in th ese patterns of N-acetyl-beta-glucosaminidase isoenzymes. The characteristi c isoenzyme patterns in the epidermis and hepatopancreas occurred consisten tly throughout the molting cycle. Injections of the molting hormone, 20-hyd roxyecdysone, at 25 mu g/g live weight, into crabs in premolt substage D-1, significantly increased N-acetyl-beta-glucosaminidase activity in the epid ermis by 86%. Since only one form of N-acetyl-beta-glucosaminidase: 89 kDa, is present in the epidermis, the elevation in epidermal enzymatic activity after 20-hydroxyecdysone administration is entirely accounted for by this N-acetyl-beta-glucosaminidase isoenzyme. The results reported herein are th e first direct evidence that in a crustacean N-acetyl-beta-glucosaminidase activity is regulated by the steroid molting hormone. (C) 1999 Elsevier Sci ence Inc. All rights reserved.