CYP1A localization in Beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary and the Arctic

Hepatic CYP1A levels in Arctic Beluga correlate with blubber content of non-ortho and mono-ortho PCBs (TAP, 1994, 126:45). Beluga from the St. Lawrence had PCB concentrations of 61 100 (females) and 79 200 (males) ng/g (Environmental Pollution 1996, 93:235), 25× the concentrations in Arctic beluga (Environmental Pollution 1990, 66:1). High level exposure to PCBs could elicit effects in multiple target organs, which may be identified by CYP1A expression. We examined CYP1A levels in organs of whales from the St. Lawrence, Hudson Bay and Mackenzie Delta. Liver, lung, kidney, gonad, brain, bladder, adrenal, skin, heart, thyroid and colon stained with the 1A1-specific monoclonal 1-12-3 all showed CYP1A in epithelial and/or endothelial cells. Strong staining occurred in hepatocytes, in transitional epithelium of the bladder, and in spermatogenic cells including Sertoli cells. CYP1A was expressed generally in endothelial cells, and was especially high in lung endothelia. St. Lawrence females showed increased CYP1A content with age in lung but not in liver. Males from Hudson Bay did not show any relationship between age and CYP1A expression in lung or liver. There was no apparent difference in CYP1A levels between juveniles and adults. Thus, CYP1A expression, ostensibly induction, is widespread in beluga organs. Examination of the relationship between the level of expression and contaminant burdens may be made between these populations. [Support: NSERC scholarship; JYW, and Sea Grant NA46RG0470-R/P61; JJS]