Nutritional, environmental, and genetic regulation of toxicity and growth in Dinophysis

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The dinoflagellate genus Dinophysis is important from ecological, evolutionary, and public health perspectives. In the former category, some members of this genus derive their nutrition through a unique, multi-stage process requiring cryptophyte and ciliate prey. Evolutionarily, the modification of cryptophyte chloroplasts during feeding and their subsequent utilization for photosynthesis provides a model system for investigations of plastid acquisition and evolution. From the public health perspective, Dinophysis species are responsible for the vast majority of diarrhetic shellfish poisoning (DSP) cases. DSP is a syndrome predominantly associated with consumption of shellfish that have accumulated Dinophysis toxins. It is a major health and economic problem for many countries and is among the most important and widespread of the harmful algal bloom (HAB)-associated poisoning syndromes.For decades, many aspects of Dinophysis physiology, toxicity, and genetics have remained intractable due to our inability to grow and maintain these organisms in laboratory cultures. As a result of a recent breakthrough, however, this obstacle no longer exists and an array of important experiments and measurements are now possible. The opportunities for major advances on multiple fronts are significant. The investigators will conduct a comprehensive study to investigate nutritional, environmental, and genetic regulation of toxicity and growth in Dinophysis. Their overall hypothesis is that toxin variability in Dinophysis is regulated not only by genetic differences among Dinophysis species and strains, but also by differences in ciliate and cryptophyte food availability and quality, and by environmental influences as well. They will establish and genetically characterize a geographically diverse culture collection that will include a variety of isolates of Dinophysis, Myrionecta and other ciliates, and cryptophytes. Much of this culture collection has already been assembled in advance of this submission. The culture assemblage will then be used to investigate Dinophysis and ciliate feeding selectivity, grazing rates, and growth. The next major objective is to explore mechanisms underlying toxin variability in Dinophysis. This will include analysis of geographically dispersed Dinophysis isolates fed with an array of ciliates and cryptophytes, as well as an examination of the role of environmental factors such as temperature, light, and nutrients in toxin production. The research project will rely on a proven system and methods - cultures of Dinophysis that have been growing at high rates in the PI's laboratory many months, established experimental protocols, and sophisticated toxin chemistry using state-of-the-art instruments and techniques. This project will begin to answer longstanding questions in dinoflagellate physiology, ecology, toxicity, and evolution while providing valuable information on a significant public health and economic problem.Broader Impacts. This project lends itself to undergraduate, graduate, and postdoctoral training. PI Anderson will support a PhD student on this project and will involve several undergraduate interns in the study as well. Anderson typically supports several Northeastern University interns who work in the laboratory for 6 months to obtain experience to guide education and career options. Postdoctoral Scholar Juliette Smith will participate in the toxin analysis, on a WHOI fellowship. The resulting culture collection will be shared with others working in this field to accelerate scientific progress. Project results will be broadly disseminated through scientific papers, presentations at workshops, conferences, and seminars, and discussions with the media. Furthermore, since the organisms being studied are responsible for a major form of shellfish poisoning that affects countries throughout the world, this project has significant practical implications that readily satisfy the criterion fostering connections between discoveries and their use in the service of society.