TESTOSTERONE-METABOLISM IN IMPOSEX AND NORMAL ILYANASSA-OBSOLETA - COMPARISON OF FIELD AND TBTA CL-INDUCED IMPOSEX

Tributyltin (TBT) is a marine biocide that alters activity of cytochro me P450 (P450) monooxygenases and elicits androgenization in gastropod molluscs. This study was conducted to determine whether testosterone metabolism was altered in field collected and TBT-induced imposer fema le mud snail, I. obsoleta. Normal and imposer snails were collected fr om two field sites. Imposer was induced by exposing normal snails to 2 .5, 5.0, 10, 20, or 200 ng TBT l(-1) seawater for 45 days at 19 degree s C, Testosterone metabolism was studied by exposing snails to [C-14]- testosterone for 24 h and determining conversion by phase I (P450s and reductases) and phase II (transferases) enzymes. All snails took up s imilar levels of testosterone from seawater, and radioactivity partiti oned primarily into gonad/digestive gland complex. Testosterone was me tabolized primarily by reductases. Field collected imposer snails had decreased rates of reduced metabolites, while there was no overall cha nge in testosterone metabolism in TBT-induced imposer snails. These fi ndings indicate that field-collected imposer snails metabolize testost erone differently from normal snails, as well as from TBT-induced impo ser snails. (C) 1998 Elsevier Science Ltd. All rights reserved.