【Special Issues: Bioassay with Molecular Techniques】
Potential Application of Molecular Techniques for the Evaluation of Endocrine-disrupting Chemicals in Leachate from Waste Landfill
Hiroshi Ishibashi*, Nobuaki Tominaga** and Koji Arizono*
* Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto
** Department of Chemical and Biological Engineering, Ariake National College of Technology
† Correspondence should be addressed to Hiroshi Ishibashi:
Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto
（3-1-100 Tsukide, Kumamoto, 862-8502 Japan）

Abstract
We critically review the current and potential application of molecular techniques in assessing the adverse biological reproductive effects of endocrine-disrupting chemicals（EDCs）in leachate from waste landfills. Various in vitro screening assays have been developed to evaluate EDCs that may bind to sex hormone receptors. Screening assays such as the receptor-binding assay to check the direct binding ability of a chemical with the receptor and the use of cultured cells such as MCF-7 cells and yeast cells in which the receptor gene is inserted are frequently used. As for in vivo assays, plasma and/or hepatic vitellogenin induction assays to determine estrogenic activity have been used in fish and amphibians. In addition, molecular techniques, such as real-time polymerase chain reaction（PCR）and cDNA-microarray, are considered to be useful tools for risk assessment of animals and humans exposed to leachate from waste landfills. This review provides a link between traditional single-gene biomarker studies and the emerging field of eco-toxicogenomics, demonstrating the utility of microarray studies on environmentally sampled, non-model organisms.

Key words: bioassay, estrogenic activity, DNA microarray, vitellogenin