Meeting Abstract
Unlike traditional lab models, the American alligator is a long-lived apex predator that displays high site fidelity, and thus represents an ideal model in which to examine the effects of long-term, chronic exposures to complex mixtures of environmental contaminants. When compared to alligators living in relatively pristine environments, alligators living in environments contaminated with endocrine-disrupting contaminants display a suite of reproductive disorders. Among these, the expression of CYP19A1 (Aromatase), a key gene within the estrogen synthesis pathway, is misregulated in animals originating from contaminated environments. We have previously shown that the promoter of CYP19A1 undergoes sexually dimorphic DNA methylation patterning, with males displaying hyper-methylation when compared to females. Here, we employ targeted bisulfite-sequencing on the Illumina platform to examine methylation patterning at the CYP19A1 promoter and other loci within male and female embryos across sites with varying contamination levels. We find that sexually dimorphic CYP19A1 promoter methylation is significantly abated in embryos originating from a contaminated site (Lake Apopka) when compared to females from a relatively pristine site (Lake Woodruff). This reduction in sexual dimorphism is due to elevated gonadal methylation within females from Lake Apopka. We next examined the effect of embryonic estrogen exposures on CYP19A1 and report these findings. These results suggest that sexually dimorphic DNA methylation patterning may be a target of endocrine disrupting contaminants in an established sentinel species.
