Cytochrome P450 1A1 and Aromatase (CYP19) in Cetaceans: Enzyme Expression and Relationship to Contaminant Exposure.

摘要

Contaminant exposure has been associated with toxicity in cetaceans. Early biochemical responses prior to, but associated with, contaminant-induced toxicity will aid in understanding the susceptibility of cetaceans to contaminants. Cytochrome P45O lAl (CYPlAl) induction by certain polychiorinated biphenyls (PCBs) has been correlated with toxicity in rodents. CYPlAl expression was measured in organs from beluga whales and white-sided dolphins and integument biopsies from bottlenose dolphins. Age and sex do not influence CYPlAl expression in these species. Mono-ortho PCB concentrations were correlated with CYP lAl in bottlenose and white-sided dolphin. White-sided dolphins have higher PCB concentrations hut lower hepatic CYPIAl expression than beluga. Beluga thus appear sensitive to CYPlAl induction by PCBs. These studies demonstrate that comparative studies between cetacean species could determine the relative susceptibility of cetaceans. Aromatase is responsible for estrogen production and studies suggest that PCBs may alter its activity. The sequence and catalytic properties of a cetacean aromatase were similar to other mammalian aromatases. Evolutionary analyses of vertebrate aromatases revealed striking functional conservation. These data show that aromatase studies in other mammals are applicable to cetacean species. Experimental work in model organisms, coupled with studies in cetaceans, could infer the physiological role and transcriptional control of cetacean aromatase.