Epel 96-04354 This one year grant will fund a pilot project aimed at understanding how embryos defend themselves against environmental toxins. Dr. Epel hypothesizes that the P-glycoprotein drug transporters provide this protection, acting as a first line of defense to keep toxins out of the cell. It is present in embryos and adults of a mud-dwelling worm, Urechis caupo, and its activity protects its embryos against added test toxins. This protection might account for the ability of Urechis embryos to develop normally in pore water (the supernatant sea water from the mud flat sediments). The embryos of starfish and sea urchins do not possess this transporter and their embryos cannot develop in pore water from the mud flats. If this drug transporter in fact protects embryos, then expression of the transporter in the embryos of the sea urchin or starfish should confer protection against environmental toxins. The major goal of this one year pilot study is to express this transporter, using the gene cloned from the mouse or nematode worm, in starfish or sea urchins oocytes and to determine if the resultant embryos will develop. If so, a large number of questions can then be asked and answered about the role of this transporter in protection of embryos and also about protection against toxins in the marine environment in general. This transporter is not ubiquitous in the marine environment, and our limited survey indicates its presence in filter and suspension feeders but not in sea urchins or starfish. A second question we wish to address in this pilot study relates to the distribution of this transporter. It is present in an echiuroid worm which lives in sediments. Is having this transporter a general attribute of being an echiuroid? Or is it something restricted to animals whose lifestyle exposes them to toxins (such as sediment dwelling or filter feeding)? To provide an answer to this question, a minor component of this pilot study will determine whether the transport protein is ex pressed or over expressed in members of this group that live in clean habitats or have different lifestyles. Providing answers to these two questions, especially information about the expression of the cloned transporter gene in echinoderm embryos, will indicate will indicate the feasibility of research approaches using expressed genes in embyros. These approaches, if feasible, would provide rigorous information on the biology of embryo defense mechanisms in general and the role of this drug transporter in particular
