【Special Issues: Bioassay with Molecular Techniques】
A Transgenic Plant that Detects Estrogenic Activity
Takuto Tojo*, Kenichi Tsuda*, Tomoko Wada* and Ken-ichi Yamazaki*
* Laboratory of Environmental Molecular Biology, Graduate School of Environmental Earth Science, Hokkaido University
† Correspondence should be addressed to Ken-ichi Yamazaki:
（Kita 10, Nishi 5, Kita-ku, Sapporo, 060-0810 Japan）

Abstract
A multitude of physiological processes are regulated by the endocrine system in animals. Endocrine-disrupting chemicals（EDCs）can potentially affect physiological processes of an organism by binding to steroid hormone receptors. Therefore, it is necessary to develop methods that can detect the presence of and effectively remove EDCs from the environment. We have developed an easy-to-use and inexpensive reporter gene assay system using transgenic Arabidopsis thaliana that can detect estrogenic activity. This transgenic plant constantly expresses two effector proteins, chimeric estrogen receptor and chimeric co-activator, in its nuclear. Estrogen-dependent interaction between the two effectors cause transcriptional activation of reporter gene, β-glucuronidase（GUS）. This transgenic plant has the capability to detect the existence of 17β-estradiol at a concentration of 50 pM（13 pg/mL）in agar medium. The plant could also detect other estrogen-like substances like diethyl stilbestrol, p-n-nonylphenol, bisphenol A, and genistein.

Key words: bioassay, endocrine disrupting chemicals（EDCs）, estrogen receptors, reporter assay, transgenic Arabidopsis