CALLARD, I.P.; WON, S.J.; NOVILLO, A.; FITZGERALD, K.; LI, C.; Boston University: Caenorhabitis elegans and Elliptio complanata: steroid responses and potential steroid response pathways

In order to gain basic understanding of the reproductive and developmental effects of endocrine disrupters in invertebrates, we are currently using two different invertebrate taxa: the nematode worm (C. elegans) and the fresh water mussel (E. complanata) as animal models. C. elegans is particularly advantageous for these studies based on a significant literature in biomonitoring , knowledge of its genome and the possibility to use DNA microarrays. Although a significant body of knowledge exists indicating a steroidogenic pathway similar to that of vertebrates in the mollusca, estradiol has not been definitively identified, nor have steroid receptors with homology to those of vertebrates been identified yet in invertebrates. In this regard, this paper addresses two basic relevant questions: is vitellogenin a biomarker of estrogenic action in invertebrates; and what type of receptor mediates the steroid response? Using western blot analysis, we will describe vitellogenin responses to steroids and heavy metals in C. elegans, as well as microarray data from the same studies, and discuss the data with regard to potential orphan nuclear receptors. Using E. complanata, we will describe changes in vitellogenin during natural conditions and after estradiol treatments. In addition, the presence and tissue distribution of estrogen receptor like proteins in the freshwater mollusk will be assessed by western blot analysis using a polyclonal antibody that targets the amino acid terminus of human ERb. The data will be reviewed in the context of endocrine disrupting chemical (EDC) effects in vertebrates and invertebrates in the aquatic environment. Supported by NIH ES 07381 to IPC and a Postdoctoral Fellowship from Spanish Government to AN.