Effects of Estrogenic Agents on Chitobiase Activity in the Epidermis and Hepatopancreas of the Fiddler Crab,Uca pugilator

The effects of exposure of the fiddler crab,Uca pugilator, to the estrogenic xenobiotics Aroclor 1242, diethylstilbestrol (DES), endosulfan, and 4-octylphenol on chitobiase activity in the epidermis and hepatopancreas were investigated. Endosulfan at 0.05 and 0.20 mg/liter significantly inhibited chitobiase in the epidermal and hepatopancreatic tissues ofU. pugilatorexposed for 3 days. After a 7-day exposure there was a significant decrease in epidermal chitobiase activity in the animals exposed to Aroclor 1242 at 8.0 mg/liter, DES at 5.0 mg/liter, and endosulfan at 0.05 and 0.20 mg/liter, while Aroclor 1242 at 2.0 and 8.0 mg/liter and endosulfan at 0.05 and 0.20 mg/liter significantly inhibited chitobiase activity in the hepatopancreas. 4-Octylphenol at 2.0 and 10.0 mg/liter had no significant effect on epidermal chitobiase activity, while 7 days of exposure to 10.0 mg/liter 4-octylphenol significantly inhibited hepatopancreatic chitobiase activity. Because chitobiase is necessary for the partial digestion of the chitinous exoskeleton as part of the molting process, inhibition of this enzyme by these estrogenic agents can account for at least some of the slowing of molting that occurs when crustaceans are exposed to these agents. Possible mechanisms regarding the decline of chitobiase activity in the presence of estrogenic agents are presented.