PARENT SESSION
PT3 - Adaptation/Acquired Environmental Resistance
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall
(P588) Are mummichogs, Fundulus heteroclitus, thriving in harsh chemical environments immunologically privileged, or are they immunocompromised?
Rice, Charles*,1, Frederick, Lee1, van Veld, Peter2, 1 Clemson University, Clemson, SC, USA2 Virginia Institute of Marine Science, College of William & Mary, Gloucester Pt, VA
ABSTRACT- Several populations of the mummichog, Fundulus heteroclitus, an estuarine killifish, exhibit characteristics of resistance or adaptation to high levels of priority pollutants along their east coast, North America range. One such population inhabits the upper Elizabeth River sub-estuary in VA at the Atlantic Wood (AW) site. Atlantic Wood is heavily contaminated with creosote containing a mixture of PAHs and some organometallics. Robust individuals of both genders comprise a large and thriving population at this site. Virtually all adults eventually develop various hepatic tumors, and these fish are recalcitrant to BAP-induction of EROD activity, yet they over-express a form of GST, as well as p-glycoprotein multidrug resistance (MDR) protein. Although PAHs are known to be immunotoxic, the resident mummichog population seems to thrive. Mummichogs from the AW site and from a reference site near Georgetown, SC USA were examined for circulating antibody titers against ubiquitous marine bacteria, including V. anguillarum, V. parahemolyticus, V. natriegens, E. coli and Mycobacteria marinum, as well as circulating lysozyme protein. The expression of hepatic CYP1A protein, lymphoid lysozyme protein, and major vault protein (MVP) expression (a MDR protein) were also examined. In addition, circulating specific antibodies for hepatic microsomal proteins, an indicator of chemical-induced hypersensitivity, were examined. Compared to high responses in reference fish, AW mummichogs had very low to non-detectable antibodies against all bacteria examined, but expressed higher circulating lysozyme. However, AW mummichog lymphoid cells expressed more MVP, more CYP1A, and more lysozyme, thus indicating a state of activation and possible resistance. Some AW mummichogs produced auto-antibodies against microsomal proteins, indicating susceptibility to chemical-induced hypersensitivity. Taken together, our findings suggest that AW mummichogs are either immunocompromised, or that the contaminants are microbicidal, thus the fish are not exposed to the pathogens in question. Furthermore, autoimmunity and chemical hypersensitivity in mummnichogs may be one of the costs associated with adaptation to the contaminants at the AW site.
Key words: adaptation and resistance, immune privilege, chemical hypersensitivity, creosote