Novel cytochrome P450 1 genes in marine vertebrates: Characterization and expression of multiple CYP1B genes in the fish Stenotomus chrysops and of CYP1A1 and CYP1B1 in the cetacean Stenella coeruleoalba

Date

2000-12

Journal Title

Journal ISSN

Volume Title

Publisher

Texas Tech University

Abstract

The cytochrome P450 1 subfamily of enzymes is of particular interest in environmental toxicology because its members (CYPIA and CYPIB proteins) are responsible for the metabolism of most polycyclic aromatic hydrocarbons, planar polychlorinated biphenyls, and aryl and heterocyclic amines. The marine environment is considered the final sink for many of these contaminants and knowledge of CYPl enzymes in marine species is critical to assess both their health and that of the oceans. Here, I report on the identification of novel CYPl genes in the marine fish scup (Stenotomus chrysops) and the cetacean striped dolphin (Stenella coeruleoalba). Two full-length CYPIB sequences were isolated from scup liver. The two fish CYPlBs, CYP1B2 and CYP1B3, share 80% and 44-46% amino acid identity with each other and mammalian CYPlBs, respectively. Sequence analysis suggests the two scup CYPlBs may have catalytic functions and/or substrate specificity that differ from each other and from those of mammalian CYPlBs. This is the first report on a full-length fish CYPIB and on multiple CYPlBs in any species. Expression of scup CYPIB genes was assessed in untreated and TCDF-treated animals by semiquantitative RT-PCR (SQRT-PCR). CYP1B2 expression levels were higher than those of CYP1B3 in liver and head-kidney of sexually mature untreated male scup but the pattern was reversed in untreated or TCDF-treated gonadally regressed animals, suggesting different physiological roles and/or regulation patterns between the two genes. Partial CYPlAl and CYPIBI sequences were isolated from striped dolphin testis and liver, respectively. The 405 AA CYPlAl and 341 AA CYPIBI dolphin sequences share 36% AA identity and of all homologous sequences currently available are both more closely related to human than any other species. Sequence analysis suggests possible similarity in substrate specificity between the dolphin and other mammalian CYPl genes. This is the first report on CYPlAl in striped dolphin and CYPIBI in any marine mammal. I designed pan-cetacean primers for CYPlAl and CYPIBI and a SQRT-PCR technique allowing detection of the two CYPl genes in cetacean tissues and biopsies. The level of CYPIBI expression was higher than that of CYPlAl in all biopsies and organs of striped dolphin

Description

Keywords

Cytochrome P-450, Osteichthyes -- Effect of water pollution on, Molecular toxicology, Pathology, Molecular, Environmental monitoring, Stenella coeruleoalba -- Effect of water pollution

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