The Interactive Effects of Light & Nutrient Source on the Molecular Regulation of Nitrogen Assimilation, Photochemistry, & Growth of Two Raphidophyte Species from DE's Inla

了解浮游植物种群动态的环境和生物因素是水生生态学研究的核心目标。 虽然我们对氮和光等个体变量如何影响浮游植物了解很多，但对这些参数的相互作用却知之甚少。 特别是硝酸盐的利用率在很大程度上取决于吸收的光量。 硝酸还原酶是一种参与硝酸盐同化的酶，也被证明可以在强烈的阳光下通过吸走多余的光能来防止光合作用受到损害。两种有害的藻类，赤潮异弯藻和盐生查顿藻，经常在特拉华州的内陆海湾大量繁殖。它们是研究营养和光照相互作用的绝佳对象，因为它们都在强光照射期间开花，但更喜欢不同的氮源。 在本项目中，将确定每个物种在不同光照水平下的氮吸收率。 将研究光、温度和养分供应在硝酸还原酶调节中的作用，并评估硝酸还原酶和其他生化途径对光合作用的影响。 这项研究将在多个层面上研究碳和氮利用之间的联系，从碳和氮调节基因的表达，到光生物学，再到自然藻类群落的变化。 这项工作的结果将有助于有害藻华发展的生态模型的发展和更好地表征影响浮游植物生态的主要因素。 这项研究将直接涉及研究生和本科生的培训和教育。 计划通过印刷品和讲座以及针对初中和高中学生的互动网站向公众传播研究成果。

Understanding the environmental and biological factors that contribute to phytoplankton population dynamics is a central goal in the study of aquatic ecology. Although much is known about how individual variables such as nitrogen and light impact phytoplankton, little is known about the interactive effects of these parameters. The utilization of nitrate, in particular, is largely controlled by the amount of light absorbed. Nitrate reductase, an enzyme involved in assimilating nitrate, has also been shown to prevent damage to photosynthesis by siphoning off excess light energy during periods of intense sunlight. Two harmful algal species, Heterosigma akashiwo and Chattonella subsalsa, often bloom in Delaware's inland bays. They make excellent subjects for investigating the interactive effects of nutrients and light, as they both bloom during periods of high light exposure yet prefer different sources of nitrogen. For this project, rates of nitrogen uptake will be determined at different light levels for each species. The roles of light, temperature and nutrient availability in the regulation of nitrate reductase will be examined, and the impact of nitrate reductase and other biochemical pathways on photosynthesis will be evaluated. This research will examine links between carbon and nitrogen utilization at multiple levels, from expression of carbon- and nitrogen- regulated genes, to photobiology, to shifts in natural algal communities. Results of this work will contribute to the development of ecological models of harmful algal bloom development and a better characterization of the primary factors that impact phytoplankton ecology. This research will directly involve the training and education of graduate and undergraduate students. Dissemination of research results to the public is planned through both print and lecture presentations and an interactive website targeting middle and high school students.