PARENT SESSION

PH14 Ecotoxicogenomics
Exhibit Hall
8:00 AM - Thursday

(PH159) Gene expression profiling of ER and AhR agonists interactions in hepatocyte culture of rainbow trout.

Arukwe, A¹, Tolfsen, C², Mortensen, A¹, ¹ Norwegian University of Science & Technology (NTNU), Trondheim, NORWAY² University of Bergen, Bergen, NORWAY

ABSTRACT- Previously, we demonstrated for the first time in fish or any other lower vertebrate, the apparent stimulation of xenoestrogen-induced (Nonylphenol; NP) responses by an antiestrogenic CYP1A-inducer (3,3,4,4-tetrachlorobiphenyl; TCB). However, the stimulatory or inhibitory effect of TCB on NP-induced responses appeared to be dependent on the ratio of NP and TCB doses, and temporal sequence of exposure. The present study was designed to investigate the mechanism(s) behind these responses using primary hepatocyte cultures from Rainbow trout. Hepatocytes were isolated by a two-step perfusion method and cultured for 48 h before exposure. Hepatocytes were treated with different concentrations of NP (5 and 10 M) singly or in combination with different concentrations of TCB (0.1, 1.0 and 10 M). CYP1A, vitellogenin (Vtg), zona radiata protein (Zrp), were studied in total RNA samples using Northern blotting for transcript identification and quantitative polymerase chain reaction (qPCR) for transcript quantification. Preliminary results show that NP exposure induced significant elevations of CYP1A, Vtg and Zrp gene expressions, while combined exposure with TCB antagonized these responses, with the 5 M NP induced responses being severely antagonized compared with the 10 M NP exposed cells. We are currently analyzing the samples for estrogen receptor (ER,) and Ah-receptor (AhR,) gene expressions in total RNA and for Zrp and Vtg protein expressions in media samples collected at different time intervals after exposure.

Key words: Xenobiotics, Xenoestrogen, Gene interactions, Anti-xenoestrogenicity