Rig: Enzymatic Detoxifying Systems For Diet-Derived Chemicals In Herbivorous Marine Fish

<p>Diverse chemical compounds play critical roles in the defenses of many marine organisms and can influence the community structure of entire ecosystems. This complexity reaches a peak on tropical coral reefs, which are well-known targets for prospecting biomedical agents. Although many marine natural products have been studied for biomedical activity, yielding important information about their biochemical effects and mechanisms of action, much less is known about predators' abilities to overcome these defenses. It is important to understand how predators cope with poisons in their diet (from prey biochemical defenses) and how these systems parallel human's ability to remove foreign chemicals that are encountered in their every day lives (drugs, pollutants, toxins, etc.) This project's use of herbivorous reef fish to define mechanisms of tolerance to chemically-rich diets will help fill important gaps: Fish that have evolved in (and depend on) chemically-rich coral-reef environments should be valuable models for studying mechanisms of xenobiotic tolerance. This knowledge will help to develop marine natural products as biomedical resources for humans; and, mechanisms of xenobiotic tolerance in herbivorous fish will provide fascinating and potentially insightful counterparts to mechanistic studies in well-studied terrestrial organisms such as insects. The vast majority of vertebrates are fishes, yet little is currently known about how fish tolerate their preys' biochemical defenses especially in tropical marine communities, where these mechanisms can be assumed to be highly developed. A state of the art genetic approach will characterize all genes expressed in the liver of S. spinus, a fish species that broadly represents chemically resistant tropical herbivorous fishes. These genes will be used to build a microarray chip to quantify changes in gene expression in response to differing environmental conditions. All gene sequences will be submitted to the National Center for Biological Information (available on http://www.ncbi.nlm.nih.gov/.) This work will provide an opportunity to define diet-driven adaptive mechanisms in tropical herbivorous vertebrates for the first time, and increase understanding of herbivore offense. Guam's island community has strong ties to the ocean, making marine science a valuable opportunity for presenting locally relevant scientific concepts and methods to a public to whom science often seems foreign. Public presentations and paid summer high-school research internships and the involvement of undergraduate and graduate biology majors will help to expand these opportunities. A better understanding of tropical fishes' mechanisms for coping with dietary xenotoxins can contribute to resource-management efforts to minimize impacts from nuisance species' of alga (e.g., cyanobacteria and other 'harmful algal blooms'; ciguatera poisoning). This project also has potential for initiating additional collaborative efforts towards ecologically relevant metabolomic and proteomic analyses of S. spinus. For people that depend on the ocean for food, understanding why some natural products persist in marine food chains can be equivalent to understanding the size and/or safety of their most important resource.</p>