Cloning of estrogen receptor alpha and aromatase cDNAs and gene expression in turtles (Chrysemys picta and Pseudemys scripta) exposed to different environments.

Reproductive changes have been observed in painted turtles (Chrysemys picta) from a site with known contamination located on Cape Cod, MA, USA. We hypothesize that these changes are caused by exposure to endocrine-disrupting compounds and that genes playing a significant role in reproduction are affected. cDNA sequences were determined for estrogen receptor alpha and aromatase in the painted turtle. These genes were measured in our study animals using quantitative PCR. Adult turtles were trapped from our study site (Moody Pond, MP) or a reference site (Washburn Pond) and exposed to laboratory environments containing soil from either site. The red-eared slider (Pseudemys scripta), a pond turtle closely related to the painted turtle, was used to assess neonatal exposure to soil and water from the sites. Our results show an increase in hepatic estrogen receptor, which suggests exposure to estrogenic contaminants. Female turtles from MP appear to have a long-term effect on hepatic ER. Other findings were apparent age-dependent differences in expression of aromatase and ER in the brains of neonate and year-old juvenile turtles. Phylogenetic analyses of the cDNA sequences further support the hypothesis that turtles are in a sister clade to birds and crocodilians.