Meeting Abstract

P3.41  Sunday, Jan. 6  Crustacean ethoxyresorufin O-deethylase activity varies during the molting cycle HOTARD, K; ZOU, E*; Nicholls State Univ, Thibodaux, LA; Nicholls State Univ, Thibodaux, LA em.zou@nicholls.edu

Ethoxyresorufin O-deethylase (EROD) activity has widely been used as a biomarker for organic pollution. However, since much of crustacean physiology is cyclic, EROD activity could also fluctuate during the molting cycle, which would call into question the use of crustacean EROD as a biomarker for organic pollution without distinguishing molt stages of crustacean specimens. This study aimed to address a fundamental question in crustacean toxicology, that is, is crustacean EROD activity influenced by the molting physiology? Using the fiddler crab, Uca pugilator, as the model crustacean, we investigated whether microsomal EROD activity in the hepatopancreas fluctuates during the molting cycle. Results showed that microsomal EROD activity varies significantly during the molting cycle, with the lowest enzymatic activity occurring in late premolt stage. These results clearly show that crustacean EROD activity is influenced by the molting physiology, suggesting that when using crustacean EROD assays in evaluating pollution, only individuals from the same molt stage should be used. Based on an inverse relationship between EROD activity and ecdysteroid titers, we propose that the high level of EROD activity in postmolt and intermolt stages is an additional mechanism used by crustaceans to prevent any untimely rise in ecdysteroid levels.