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 cytochrome 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 imposex female mud snail, I. obsoleta. Normal and imposex snails were collected from two field sites. Imposex 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°C. Testosterone metabolism was studied by exposing snails to [14C]-testosterone for 24 h and determining conversion by phase I (P450s and reductases) and phase II (transferases) enzymes. All snails took up similar levels of testosterone from seawater, and radioactivity partitioned primarily into gonad/digestive gland complex. Testosterone was metabolized primarily by reductases. Field collected imposex snails had decreased rates of reduced metabolites, while there was no overall change in testosterone metabolism in TBT-induced imposex snails. These findings indicate that field-collected imposex snails metabolize testosterone differently from normal snails, as well as from TBT-induced imposex snails.