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PW05 Genomics and Proteomics
(PW89) Identification of novel genes associated with natural resistance to PCB-induced early life stage toxicity in Atlantic tomcod populations.
Carlson, E.1, Roy, N.1, Marzinke, M.1, Wirgin, I.1, 1 New York University School of Medicine, Tuxedo, New York, US
ABSTRACT- Carlson, Erik A., Roy, Nirmal K, Marzinke, Mark and Wirgin, Isaac New York University School of Medicine, Tuxedo, New York Resistance to halogenated aromatic hydrocarbon (HAH)-induced toxicity has been observed in natural populations chronically exposed to HAH compounds. For example, Atlantic tomcod Microgadus tomcod from the Hudson River (HR) exhibit reduced sensitivity to the toxic effects of coplanar PCBs and TCDD compared to fish from the Miramichi River (MR), NB. Tissue burdens of HAHs congeners are much higher in unfertilized eggs and livers of adult and juvenile tomcod from the Hudson River (HR) compared to tomcod from elsewhere. In controlled laboratory experiments, early life stage toxicities (i.e., lethality, pericardial and yolk-sac edema, and craniofacial malformations) were observed in MR tomcod exposed to environmentally-relevant mixtures of PCBs, similar exposures of laboratory-reared F1 and F2 offspring of HR fish failed to produce such effects. In an attempt to discover novel genes that may be involved in PCB-induced toxicity and resistance, custom tomcod cDNA microarrays were developed. cDNA libraries were made from heart and head kidney tissues of untreated tomcod to serve as sources of candidate genes involved in cardiovascular and immune system dysfunction, respectively. Plasmid inserts from library clones were PCR amplified and robotically printed onto glass microscope slides. Each array consisted of either 4000 heart- or 2000 kidney-derived cDNAs spotted in triplicate. Microarrays were then used to identify genes that were differentially-expressed between control and PCB-exposed tomcod embryos, larvae, and adults from both resistant and sensitive populations. To date, PCB-inducible genes determined in MR fish, as expected, include both cytochrome P450 1A1 (CYP1A1) and the aryl hydrocarbon receptor repressor (AHRR). Furthermore, two orders of magnitude higher concentrations of PCBs are required to induce CYP1A1 and AHRR in offspring of HR tomcod compared to those from MR. These tomcod microarrays represent one of the first attempts to identify differentially expressed novel genes anchored to phenotypic alterations in feral populations of fish.
Key words: PCBs, microarrays, resistance, Atlantic tomcod
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