PARENT SESSION
PW1 - Molecular/ Cellular Toxicology
Wednesday, 20 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P726) Alterations in the expression and inducibility of genes in the aryl hydrocarbon receptor (AhR) pathway in wild-caught killifish (Fundulus heteroclitus) from a creosote-contaminated site.
Wassenberg, Deena*,1, Meyer, Joel1, Manke, Jeanette1, Karchner, Sibel2, Hahn, Mark2, Di Giulio, Richard1, 1 Duke University, Durham, NC, USA2 Woods Hole Oceanographic Institution, Woods Hole, MA, USA
ABSTRACT- Wildcaught killifish from a contaminated site on the Elizabeth River (VA) are refractory to induction of cytochrome P4501A (CYP1A, measured as catalytic activity and CYP1A protein levels) after exposure to typical aryl hydrocarbon receptor (AhR) agonists, as has been reported for killifish from other sites highly contaminated with AhR agonists (New Bedford Harbor, Newark Bay). In an attempt to understand the molecular basis for the reduction in CYP1A protein expression and inducibility in Elizabeth River killifish, we analyzed the gene expression of CYP1A and 4 upstream members of the AhR signal transduction pathway: AhR1, AhR2, AhRR (AhR repressor), and ARNT2 (AhR nuclear translocator 2). Gene expression was measured by semi-quantitative RT-PCR analysis of RNA extracted from livers of Elizabeth River and reference site killifish 36 hours after injection with B-naphthoflavone (BNF, an AhR agonist) or corn oil (carrier control). As observed previously for CYP1A protein and activity levels, Elizabeth River killifish show poor inducibility of CYP1A mRNA. Similarly, AhRR mRNA levels were induced in BNF-dosed reference site but not Elizabeth River killifish. No population or treatment-related differences were observed in mRNA expression levels of AhR1 or ARNT2. However, preliminary results suggested an induction in AhR2 levels in reference site but not Elizabeth River killifish. Additional experiments will examine the time course and heritability of these alterations in the AhR pathway in Elizabeth River killifish. Supported by the Superfund Basic Research Programs Grants ES10356 (RTD) and ES07381 (MEH), and by the Office of Naval Research Grant N00014-00-1-0315 (RTD).
Key words: AhR, CYP1A, adaptation, killifish