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 PARENT SESSION
2L - Immunotoxicity - genotoxicity - ED
Poster Hall
8:30 AM - Wednesday, 30 April 2003
Chair: Hansen, P.D.1, 1
(WEP/109) Identification of a sex steroid receptor like protein in the invertebrate Gammarus fossarum.
Schirling, Martin1, Köhler, Heinz.-R.1, Köhler, Anna M. I.1, Triebskorn, Rita2, Nagel, Roland3, Paul, Martin4, Schönfelder, Gilbert4, 1 Animal Pysiological Ecology, University of Tübingen, Tübingen, BW, Germany2 Steinbeis-Transfer Center for Ecotoxicology and Ecophysiology, Rottenburg, BW, Germany3 Institut of Hydrobiology Dresden University of Technology, Dresden, Saxony4 Institute of Clinical Pharmacology and Toxicology, Medical Center Benjamin Franklin Free University, Berlin, Berlin
ABSTRACT- Until now no sex steroid receptor has been found in any species outside the phylum chordata. In the non-vertebrate chordate, Branchiostoma, an estrogen receptor has been localized and it was suggested that these receptors arose in ancient deutorostome. In our present work we could identify an estrogen receptor  (ER) like protein in the amphipod Gammarus fossarum. For the experiment 10 male, 10 female and 10 juvenile gammarids were examined, using an immunoblotting assay. Uterus tissue of rat served as positive control, while vertebrate tissue not expressing estrogen receptors (tilapia gill) was used as a negative control. To check for potential cross-reactivity of the used antibody with other nuclear receptors, such as e.g. the ecdysone receptor, pools of Drosophila melanogaster larvae and legs of juvenile cockroach (Periplaneta americana) were analysed accordingly. The results of our study showed a sex-specific expression of an estrogen receptor like protein, indicating this protein likely to be a true receptor. Only in female gammarids two ER like protein variants with molecular weights of approximately 62 kDa and 45 kDa were found. These proteins are most likely homologous to the to the 64-65 kDa and 40-45 kDa ER isoforms from rat uterus. The identification and the strong sex-specificity of ER like protein in an arthropod species could have consequences for invertebrate endocrinology, the understanding of sex steroid evolution, and the risk assessment of xenosteroids in our environment.
Key words: invertebrates, estrogen receptor, Gammarus fossarum, Crustacea
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