International Research Fellowship Program: Profiling Marine Herbivore Gene Expression in Response to Algal Chemical Defenses

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0754319WhalenThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four month research fellowship by Dr. Kristen E. Whalen, University of California, Santa Barbara, to work with Dr. Peter Steinberg at the University of South Wales in Australia, and with Dr. Gretchen Hofmann at the University of California, Santa Barbara.The marriage between molecular tools and traditional methods for the study of marine algal-herbivore interactions holds considerable promise for the field of chemical ecology. Despite tremendous progress in identifying the diversity, concentrations and distribution of algal chemical defenses and their impact on marine herbivores, few studies have addressed the proximate mechanisms underlying the profound variation in tolerance among these herbivores for their chemically defended foods. Part of the problem is we have virtually no information on the physiological responses of marine herbivores mediating this interaction. Fortunately, recent advances in genomic technology will provide a detailed and unprecedented view of the mechanistic underpinnings of how cells and ultimately organisms tolerate and respond to environmental chemical stresses. Techniques such as transcriptome profiling using DNA microarrays will allow for the parallel analysis of the expression of thousands of genes and provide a complete picture of gene regulation occurring in response to dietary compounds. With the recent completion and annotation of the purple sea urchin genome, genes responsible for mediating tolerance of algal chemistry can, for the first time, be identified in a marine herbivore. The central objective of this project is to develop the sea urchin microarray as a tool for understanding broader aspects of marine herbivore physiology and resistance to dietary chemical stressors. An oligonucleotide array will be designed and constructed targeting over 2000 genes important in xenobiotic detoxification/efflux, signal transduction, nutrient metabolism and chemoreception. This custom designed sea urchin array will be used to profile gene expression in the Australian urchin Heliocidaris erythrogramma, in response to chemically diverse macroalgal diets. Transcriptome profiling will identify target genes whose temporal expression will be further assessed by real-time quantitative PCR. Furthermore, genes identified by transcriptome profiling can be targeted for additional biochemical characterization of algal compound-protein interactions. The PI anticipates this work will add volumes to our knowledge of the underlying biochemical mechanisms influencing algal-herbivore interactions, leading to a more complete understanding of marine consumer response to dietary chemical stressors and the biochemical basis of diet selection.