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(PH175) Endocrine disruption in largemouth bass: alteration of gene expression patterns by p,p' DDE and dieldrin.
Reyero, N1, Barber, D2, Kroll, K1, Johnson, K3, Sepulveda, M2, Gross, T2, 4, Denslow, N1, 5, 1 Biotechnology Program, University of Florida, Gainesville, FL, USA2 Department of Physiological Sciences, University of Florida, Gainesville, FL, USA3 Department of Fisheries and Aquatic Science, University of Florida, Gainesville, FL, USA4 USGS-BRD Florida Caribbean Science Center, Gainesville, FL, USA5 Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA
ABSTRACT- Certain environmental pollutants can alter the normal endocrine function of wildlife, leading to impaired reproduction and development. These pollutants, known as endocrine disruptors, are widespread and have become a public concern resulting in big efforts to define the extent of exposure and its physiological consequences. The chosen model for our research is largemouth bass (LMB, Micropterus salmoides), as this species is known to be sensitive to environmental chemicals. Besides, LMB are high order predators in the food chain, bio-accumulating hydrophobic xenobiotics. In order to find out the mechanisms responsible for endocrine disruption, LMB were exposed subchronically through the diet to p,p' DDE (7, 37 and 185 ppm) and dieldrin (0.1, 0.6 and 3 ppm). Using real time PCR, we are beginning to elucidate changes in mRNA expression levels for several genes that are important for reproduction, including three estrogen receptors, vitellogenin, StAR (steroidogenic acute regulatory protein), Cyp1A, Cyp3A and aromatase. Subchronic exposure to p,p' DDE increases the three estrogen receptors both in liver and gonads, although the increase is much more obvious in gonad, with highest increases of 58 fold in ER alpha (males), 49 fold in ER beta (females), and 20 fold in ER gamma (males). Vitellogenin is also highly increased, especially in females, up to 11000 fold, in some of the treatments. We also see changes in Cyp1A and Cyp3A in liver, as well as in aromatase (up to 150 fold in male) and in StAR (more than 100 fold both in females and males) in gonads. Dieldrin treatment also provokes moderate induction of all the genes tested (with the highest induction for Cyp3A in females, up to 32 fold). Our aim is to confirm these data using microarrays and to understand the biochemical mechanisms that are affected in LMB by the studied pollutants.
Key words: dieldrin, largemouth bass, p,p' DDE, estrogen receptor
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