An elevated glutathione S-transferase in creosote-resistant mummichog ( Fundulus heteroclitus)

A population of mummichog ( Fundulus heteroclitus) inhabit a site (Atlantic Wood) in the Elizabeth River, VA, heavily contaminated with creosote. Although chronic effects including hepatic neoplasms have been observed in adult mummichog, these fish are resistant to the acute effects (mortality within a few days of exposure) of the creosote-contaminated sediments while fish from a reference site are not. Increased levels and activity of glutathione S-transferases (GST) in Atlantic Wood fish may play a role in this resistance. In the present study, hepatic GSTs from Atlantic Wood and reference site fish were isolated by S-hexylglutathione affinity chromatography. A monoclonal antibody was produced that recognizes a GST that is elevated approximately six-fold in Atlantic Wood fish and two-fold in fish from a moderately contaminated site relative to fish from the reference site. GST activity towards 1-chloro-2,4-dinitrobenzene was elevated approximately four-fold and two-fold in these fish relative to fish from the reference site. The elevated GST has a molecular mass of approximately 27.2 kDa and isoelectric point of 8.1. The N-terminus of the isoform was blocked, preventing N-terminal amino acid determination.