R3 AM Ecotoxicogenomics of Emerging Chemical Issues
Thursday, 17 November 2005: 8:00 AM - 11:40 AM in Ballroom 3
(KAG-1116-226780) Hepatic gene expression analysis of 17
-ethynylestradiol-exposed Medaka using DNA microarray.
Nakamura, H1, Kawano, K1, Koshio, M2, Hirai, N2, Yoshikawa, O1, Kagami, Y1, Tatarazako, N2, 1 Ecogenomics, Inc., Kurume, Fukuoka, Japan2 National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan
ABSTRACT- Biological risk assessment using fish species for monitoring the effects of endocrine-disrupting chemicals (EDCs) has long been focused upon multi- or single-generation life-cycle tests, vitellogenin protein expression assay, and reproduction test. Although these assays are valuable and effective for risk assessment of the EDCs, we strongly feel that the power of gene expression profiling with microarray technology should be further explored to develop more comprehensive biological risk assessment system. Thus, we developed Medaka cDNA microarray, which can hold 12 different target samples for simultaneous hybridization on one microarray, and each of its hybridization chambers contained 95 estrogen-responsive gene probes (approximately 300-base-long cDNA fragments) in triplicate. These 95 gene probes were selected by our preliminary microarray gene expression experiments performed with the 17
-estradiol-exposed male Medaka livers using our EG Medaka DNA microarray (405 estrogen-responsive gene probes). In this study we were interested in the effects that would appear in male and female hepatic gene expression profiles during the 96-hour time-course experiment under 100 ppt and 10 ppt 17-ethynylestradiol (EE2) exposure conditions. During the study we were hoping to identify some other strong estrogen-responsive genes in addition to vitellogenins and choriogenins in the male liver, that were well-studied strong estrogen-responsive biomarker genes in fish species, however, the results showed no other genes to be as strongly responsive as vitellogenins and choriogenins. As for the female liver, scale of individual sample variations was too large to obtain reliable significance in the EE2-responsive and differential gene expression data. Nevertheless, cytochrome P450 1A, annexin max genes, and one particular cDNA clone had shown that they were significantly responding to the EE2-exposure in the male liver, and these results implies potentialities of those genes for future biomarker molecules for risk assessment of the estrogenic chemical compounds.
Key words: microarray, medaka, ethynylestradiol, biomarker