Meeting Abstract

P3.153  Tuesday, Jan. 6  Comparative physiology of multidrug resistance in marine invertebrate oocytes and embryos MCGINN, N.A.*; CHERR, G.N.; University of California, Davis namcginn@ucdavis.edu

Multidrug resistance (MDR) – discovered in cancer cells resistant to multiple chemotherapeutic agents – is important in normal cell function and in the protective mechanisms of tissues such as the blood-brain barrier and placenta. The efflux of target compounds that characterizes MDR is found in a taxonomically wide range of organisms where MDR performs functions similar to those in mammalian tissues. In marine invertebrates, MDR activity is found in adult tissues, notably gill, but MDR is also a functional protective mechanism in the early developmental stages of broadcast spawners. In the sea urchin Strongylocentrotus purpuratus, MDR activity was low in unfertilized eggs, but dramatically increased after fertilization. In sea stars, no such increase after fertilization was observed, however, MDR activity did increase after germinal vesicle oocytes underwent maturation in vitro. In this study, we have taken a comparative approach to better understand how MDR activity varies in oocytes and embryos from different phyla of broadcast-spawning marine invertebrates. As in S. purpuratus, MDR activity in the eggs of the sea urchin Lytechinus pictus was significantly greater after fertilization, although the level of MDR activity was lower overall. In contrast, there was no increase in MDR activity post-fertilization in either the mussel Mytilus galloprovincialis or the echiuran worm Urechis caupo. While the overall level of MDR activity in M. galloprovincialis approaches that of L. pictus, U. caupo activity was consistently lower. These differences may be a result of the maturational state of the oocytes/eggs or, perhaps, the exposure of adults to MDR substrates. We continue to investigate species with different reproductive strategies with a focus on oocyte maturation.