Dr. Epel is seeking support under the Small Grants for Exploratory Research for assistance in moving his lab into a new research direction - the cellular mechanisms by which embryos of aquatic organisms resist deleterious effects of xenobiotics, both natural and anthropogenic. He will focus on embryos since this is a particularly sensitive phase of the organism's life history. This new work combines his long term work and interest in cell and developmental biology with a new interest and concern about the effects of man-introduced chemicals into the marine environment. Besides providing new insights about embryonic defense mechanisms, this work will also yield new and unexpected insights on the normal functioning of cells in both the embryonic and adult phases of the organisms's life history. It will test the possibility that the multi-drug resistance or P-glycoproteins transport system, whose role has been primarily assumed to be of medical importance in terms of transporting hydrophobic drugs out of cells, is normally (i.e., in the historical or evolutionary sense) utilized for removal or detoxification of xenobiotics/pollutants. This idea, if correct, would provide a novel insight into how organisms, and in particular aquatic organisms, can resist the effects of man-made and natural noxious compounds. This work could also provide a "natural history" or evolutionary basis for why these proteins are present and their role in the normal life history of the organism.