HA4 Ecotoxicogenomics
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() Identification of novel genes associated with natural resistance to PCB-induced early life stage toxicity in Atlantic tomcod populations.

Carlson, E1, Roy, N1, Wirgin, I1, 1 NYU School of Medicine, Tuxedo, NY, USA

ABSTRACT- Resistance to halogenated aromatic hydrocarbon (HAH)-induced toxicity has been observed in natural populations chronically exposed to HAH compounds. For example, this laboratory has discovered that Atlantic tomcod Microgadus tomcod from the Hudson River (HR) exhibit reduced sensitivity to the toxic effects of coplanar PCBs compared to fish from the Miramichi River (MR), NB. While early life stage toxicities (i.e., lethality, craniofacial malformations, and pericardial and yolk-sac edema) were observed in MR tomcod exposed to environmentally-relevant mixtures of PCBs, similar exposures of HR fish failed to produce such effects. In an attempt to discover novel genes that may be involved in PCB toxicity and resistance, custom tomcod cDNA microarrays were fabricated. Tomcod heart mRNAs were used to construct full-length cDNA libraries to serve as sources of candidate genes involved in cardiovascular dysfunction. Each array consisted of approximately 5,000 unidentified cDNAs spotted in triplicate. Microarrays were then used to identify genes that were differentially-expressed in PCB-exposed tomcod embryos and larvae from both resistant and sensitive populations. Population-, life stage-, and exposure-specific gene expression patterns were clearly observable in these microarray analyses. To date, several genes responsive to PCB exposure in MR fish have been identified, including CYP1A1, aryl hydrocarbon receptor repressor, Y-box binding protein Y-b1, and cathespin L.

Key words: Hudson River, PCBs, Resistance, Genomics

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