Characterization of resistance to halogenated aromatic hydrocarbons in a population of Fundulus heteroclitus from a marine superfund site

Abstract

New Bedford Harbor NBH, MA, is contaminated with halogenated aromatic hydrocarbons HAH including some potent aryl hydrocarbon receptor AhR agonists. To determine ifFundulus heterocitus from NBH have developed resistance to HAll, we examined the inducibility of cytochrome P4501A1 CYP1A1 in fish from NBH and Scorton Creek SC, reference site. Despite higher PCB concentrations in NBH than in SC fish --1 500-fold -CYP1A1 expression, in most tissues, was not higher in NBH fish than in SC fish. Glutathione S-transferase GST and UDP-glucuronosyltransferase UGT activities were higher in NBH fish than in SC fish, but only when fish were collected during different seasons. GST activity was higher in the intestines ofNBH fish than in any other tissue.2,3,7,8-Tetrachlorodibenzoftiran TCDF induced CYP1A1 expression, in all tissues examined, in SC fish. In contrast, NBH fish showed little CYP1A1 induction by any measure, in any tissue. Hepatic GST activity was induced only in male NBH fish. Hepatic UGT activity showed no relationship to treatment in fish from either site.2,3,7,8-Tetrachlorodibenzo-p-dioxin TCDD and J3-naphthoflavone BNF induced CYP1A1 activity to the same level in primary cultures ofhepatocytes from either SC orNBH fish. However, hepatocytes from NBH fish were 14-fold less sensitive to TCDD and 3-fold less sensitive to BNF than hepatocytes from SC fish.To examine the heritability ofresistance, NBH and SC F1 fish were treated with 3H-TCDD or BNF. 3H-TCDD induced CYP1A1 expression only in SC F1 fish. BNF induced CYP1A1 expression in both SC and NBH F1 fish. There was no significant difference in hepatic 3H-TCDD concentrations between SC and NBH F1 fish.Hepatic AhR content, as measured by photoaffinity labeling with '25I-N3Br2DD, was lower in NBH fish than in SC fish and lower in males than in females. After 90 days in captivity, the sex difference persisted, but the site difference did not. TCDF induced hepatic AIIR content in NBH F1 fish.These results indicate that NBH Fundulus have developed a pre-translational, systemic, heritable resistance to HAHs. These findings suggest that an alteration in the AIIR pathway is responsible for this resistance; this is the subject ofcontinuing research. Next, I owe more than I can say to my thesis advisor and friend Mark Hahn. He was always available whenever I needed to consult on ideas, was endlessly tolerant of the bizarre hours I kept, and fostered a truly enjoyable work environment.Bruce Woodin was an ever accommodating and delightful person to work with. I want to thank him for all ofhis help with dissections, his enlightening field trips, and for generally making my time here that much more enjoyable. I thank Diana Franks for her work with the primary culturing of the Fundulus hepatocytes, for her help with fish care and for generally helping to make my life a little easier. Diane Nacci, Ken Rocha, and the EPA laboratory in Narragansette for kindly providing fish. Diane also for her help during the planning stages ofthis work and her willingness to exchange r...

Regulation of pregnane-X-receptor, CYP3A and P-glycoprotein genes in the PCB-resistant killifish (Fundulus heteroclitus) population from New Bedford Harbor

“…A key example is the stable population of killifish that inhabits a part of the New Bedford Harbor (NBH) in Massachusetts (MA), USA, which is heavily contaminated by polychlorinated biphenyls (PCBs) (Weaver, 1984). In the 1990s, levels of ortho -substituted PCBs (non-dioxin-like) and non- ortho -substituted PCBs (dioxin-like) were more than 1000 times higher in NBH fish than in fish from reference sites such as Scorton Creek (SC) on Cape Cod, MA (Lake et al, 1995; Black et al, 1998; Bello, 1999). The dioxin-like PCB congeners normally induce cytochrome P450 1A (CYP1A) gene expression, which is a sensitive biomarker commonly used to assess exposures to dioxin-like compounds and other planar aromatic hydrocarbons in the aquatic environment (Stegeman and Hahn, 1994).…”

Development and characterization of polyclonal antibodies against the aryl hydrocarbon receptor protein family (AHR1, AHR2, and AHR repressor) of Atlantic killifish Fundulus heteroclitus

“…Widespread and abundant, Atlantic killifish inhabit highly polluted areas where they are exposed to high concentrations of PCBs and PAHs (Lake et al 1995;Bello 1999;Nacci et al 1999;2001).…”

Fundulus as the premier teleost model in environmental biology: Opportunities for new insights using genomics

“…DLC resistance in NBH F. heteroclitus involves alterations in responsiveness of the AHR pathway in adults (Bello, 1999;Nacci et al, 1999;Bello et al, 2001;Karchner et al, 2002) as well as in embryos (Nacci et al, 1998;Roark et al, 2005). Exposure to BAP caused fewer DNA adducts in NBH fish relative to reference fish (Nacci et al, 2002c), consistent with an altered AHR pathway.…”

“…Other evidence suggested that short-term or non-heritable mechanisms may contribute to the observed differences between the NBH and reference fish. For example, freshly caught NBH fish had lower hepatic content of AHR than reference fish, but the difference was no longer detected after a 90 day depuration period in the laboratory (Bello, 1999). The DLC-tolerant phenotype of adults is not accompanied by changes in the expression of mRNA for AHR (AHR1 and AHR2), partner (ARNT), or repressor (AHRR) pathway components (Powell et al, 2000;Karchner et al, 2002).…”

“…Exposure to BAP caused fewer DNA adducts in NBH fish relative to reference fish (Nacci et al, 2002c), consistent with an altered AHR pathway. Like parental fish, progeny from NBH were generally refractory to CYP1A induction suggesting that some mechanisms of tolerance are inherited (Bello, 1999). Other evidence suggested that short-term or non-heritable mechanisms may contribute to the observed differences between the NBH and reference fish.…”