TP17 Biomarkers
Tuesday, 15 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(MOF-1117-221562) Changes in gene expression in Japanese medaka (Oryzias latipes) exposed to three different environmental contaminents.

Moffatt, L¹, Hartunian, C¹, Arcaro, K¹, ¹ University of Massachusetts, Amherst, MA, USA

ABSTRACT- Developing biomarkers of endocrine disruption is important for the detection of problematic aquatic pollutants. Changes in gene expression in aquatic organisms may serve this purpose. In this study, male and female Japanese medaka (Oryzias latipes) were exposed to three compounds, Bisphenol A, Atrazine, and Ivermectin, each of which has been detected in the environment and two of which exhibit potential reproductive endocrine disrupting activity. Bisphenol A is a monomer used in the production of plastics that has been shown to act as an estrogen. Atrazine is a common herbicide used on a variety of commercial crops in the United States and has been linked to reproductive abnormalities in amphibians. Ivermectin, a veterinary pharmaceutical, is often used in livestock herds with most of the dosage being excreted in the feces. For each chemical, three environmentally relevant concentrations were used, and fish were exposed to these compounds diluted in conditioned tank water. The expression of two reproductively important genes, vitellogenin (VTG), an egg-yolk precursor protein normally produced in the liver of females, and cytochrome P45019 (CYP19), the aromatase producing gene which is present primarily in female gonads, were then examined by quantitative RT-PCR. Preliminary results showed that Bisphenol A increased VTG expression in male livers as compared to unexposed males. Interestingly, the same compound also appeared to decrease expression of CYP19 in female gonads in a dose dependent manner but had the opposite effect in male gonads. Atrazine, however, did not appear to significantly affect the expression of these genes at the tested concentrations. Ivermectin appeared to increase the expression of VTG in male livers. Taken together, these data demonstrate that we have the ability to readily detect changes in gene expression in medaka caused by various contaminants, and changes in VTG and CYP19 may serve as biomarkers of reproductive endocrine disruption.

Key words: biomarkers, pollutants, vitellogenin, aromatase