Nutritional, environmental, and genetic regulation of toxicity and growth in Dinophysis\u00a0<\/strong><\/p>\n The dinoflagellate genus\u00a0Dinophysis<\/em>\u00a0is important from ecological, evolutionary, and public health perspectives.\u00a0 In the former category, some members of this genus derive their nutrition through a unique, multi-stage process requiring cryptophyte and ciliate prey.\u00a0 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,\u00a0Dinophysis<\/em>\u00a0species are responsible for the vast majority of diarrhetic shellfish poisoning (DSP) cases.\u00a0 DSP is a syndrome predominantly associated with consumption of shellfish that have accumulated\u00a0Dinophysis<\/em>\u00a0toxins.<\/em>\u00a0 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.<\/p>\n For decades, many aspects of\u00a0Dinophysis<\/em>\u00a0physiology, toxicity, and genetics have remained intractable due to our inability to grow and maintain these organisms in laboratory cultures.\u00a0 As a result of a recent breakthrough, however, this obstacle no longer exists and an array of important experiments and measurements are now possible.\u00a0 The opportunities for major advances on multiple fronts are significant.\u00a0 Here we propose a comprehensive study to investigate nutritional, environmental, and genetic regulation of toxicity and growth in\u00a0Dinophysis.\u00a0<\/strong>Our overall hypothesis is that toxin variability in\u00a0<\/em>Dinophysis\u00a0is regulated not only by genetic differences among\u00a0<\/em>Dinophysis\u00a0species and strains, but also by differences in ciliate and cryptophyte food availability and quality, and by environmental influences as well.<\/em>\u00a0 We propose to establish and genetically characterize a geographically diverse culture collection that will include a variety of isolates of\u00a0Dinophysis<\/em>,\u00a0Myrionecta<\/em>\u00a0and other ciliates, and cryptophytes.\u00a0 Much of this culture collection has already been assembled in advance of this submission. The culture assemblage will then be used to investigate\u00a0Dinophysis<\/em>\u00a0and ciliate feeding selectivity, grazing rates, and growth. The next major objective is to explore mechanisms underlying toxin variability in\u00a0Dinophysis<\/em>.\u00a0 This will include analysis of geographically dispersed\u00a0Dinophysis<\/em>\u00a0isolates 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 proposed work will rely on a proven system and methods \u2013 cultures of\u00a0Dinophysis<\/em>\u00a0that have been growing at high rates in the PI\u2019s laboratory many months, established experimental protocols, and sophisticated toxin chemistry using state-of\u2013the-art instruments and techniques.\u00a0 We have worked for several years (without funding) to set up the infrastructure and gain the experience needed to conduct and justify the experiments proposed here, recognizing the need to convince reviewers and others that the work is indeed feasible.\u00a0 We can say with confidence that we have reached the point where we are no longer constrained by an inability to manipulate\u00a0Dinophysis<\/em>\u00a0species in the laboratory.\u00a0 We can thus move forward and begin to answer longstanding questions in dinoflagellate physiology, ecology, toxicity, and evolution while providing valuable information on a significant public health and economic problem.<\/p>\n Relevant Publications\u00a0<\/strong><\/p>\n Hackett, J.D., L. Maranda, H.S. Yoon, and D. Bhattacharya. 2003. Phylogenetic evidence for the cryptophyte origin of the plastid of\u00a0Dinophysis\u00a0<\/em>(Dinophysiales, Dinophyceae). J Phycol.\u00a0<\/em>39:\u00a0<\/strong>440\u2013448.<\/p>\n Janson, S. 2004. Molecular evidence that plastids in the toxin-producing dinoflagellate genus\u00a0Dinophysis<\/em>\u00a0originate from the free-living cryptophyte\u00a0Teleaulax amphioxeia<\/em>. Environ. Microbiol. 6: 1102-1106.<\/p>\n Janson, S., and E. Gran\u00e9li. 2003. Genetic analysis of the\u00a0psbA\u00a0<\/em>gene from single cells indicates a chryptomonad origin of the plastid in\u00a0Dinophysis\u00a0<\/em>(Dinophyceae). Phycologia\u00a0<\/em>42:\u00a0<\/strong>473\u2013477.<\/p>\n Park, M.G., S. Kim, Y.G. Kang, and W. Yih. 2006. First successful culture of the marine dinoflagellate\u00a0Dinophysis acuminata<\/em>. Aquat. Microb. Ecol. 45: 101-106.<\/p>\n Park, J.S., G. Myung, H.S. Kim, B.C. Cho, and W. Yih, W. 2007. Growth responses of the marine photosynthetic ciliate\u00a0Myrionecta rubra<\/em>\u00a0to different cryptomonad strains. Aquat. Microb. Ecol. 48: 83\u201390.<\/p>\n