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THE BIOCIDE TRIBUTYLTIN ALTERS TESTOSTERONE ESTERIFICATION IN MUD SNAILS (ILYANASSA OBSOLETA)
Gooding, M. P. AND G. A. LeBlanc. THE BIOCIDE TRIBUTYLTIN ALTERS TESTOSTERONE ESTERIFICATION IN MUD SNAILS (ILYANASSA OBSOLETA). Presented at ehormone conference, New Orleans, LA, October 19-20, 2001.
The Biocide Tributyltin Alters Testosterone Esterification in Mud Snails (Ilyanassa obsoleta)
Meredith P. Gooding and Gerald A. LeBlanc
Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, NC 27695-7633
Tributyltin (TBT) is a ubiquitous environmental contaminant that causes imposex, the development of male sex characteristics in female Prosobranch gastropods. Testosterone is reportedly elevated in imposex individuals and has been causally implicated in the occurrence of this disorder. Previously, we had characterized normal testosterone biotransformation in the mud snail (Ilynassa obsoleta). We discovered that this imposex-susceptible species converts testosterone to fatty acid esters and that this activity is mediated by acyl CoA:testosterone acyltransferase (ATAT). The purpose of the present study was to determine whether elevated free testosterone levels associated with imposex snails may be due to the inhibition or suppression of testosterone esterification by TBT. Snails were exposed for three to six months to environmentally-relevant levels of TBT (0.1, 1.0 and 10 ng/L as tin). Imposex was induced in TBT-exposed snails in a concentration dependent manner. These snails were administered [14C]testosterone and the rate of production of [14C]testosterone ester was measured. The production of testosterone ester was decreased with increasing exposure concentration of TBT. These results indicate that TBT elevates free testosterone levels in mud snails by decreasing the rate of conversion of free testosterone to fatty-acid ester. Experiments to determine whether the TBT-induced decrease in testosterone esterification is due to the direct inhibition of ATAT or to the suppression of ATAT gene expression are presented.
Disclaimer: This abstract does not necessarily reflect EPA policy: NCSU/EPA Cooperative Agreement #CT826512010