Induction of cytochrome P4501A (CYP1A) in Trematomus bernacchii as an indicator of environmental pollution in Antarctica: assessment by quantitative RT-PCR

Abstract

Although most of Antarctica is relatively pristine, high levels of pollutants have been recorded in localised areas such as in the vicinity of scientific bases like McMurdo Station. We have used the Antarctic fish Trematomus bernacchii as an indicator species to assess the level of impact of these pollutants on the local biota. Fish were collected from Winter Quarters Bay (adjacent to McMurdo Station) and Backdoor Bay (remote from human activities). Liver samples from individual fish were used in the preparation of total RNA from which the level of expression of the cytochrome P4501A gene ( CYP1A), known to be responsive to polycyclic aromatic hydrocarbons (PAHs), was determined by quantitative competitive reverse-transcriptase polymerase chain reaction (RT-PCR). Samples of bile from the same fish were analysed for fluorescent aromatic compounds (FACs) at naphthalene and phenanthrene wavelengths to provide an indication of exposure to organic compounds such as the PAHs. The levels of biliary FACs in fish from Winter Quarters Bay were approximately 2-fold higher than those in fish from Backdoor Bay, whereas there was an average 37-fold increase in CYP1A expression between fish taken from the two sites. The extent of CYP1A induction correlated positively with biliary FACs levels, indicating the potential of quantitative competitive RT-PCR as a sensitive molecular approach to pollution impact assessment. Fish from Winter Quarters Bay also had significantly higher hepatosomatic and gonadosomatic indices indicative of altered organ function, although the extent to which this might be related to pollution is uncertain.