Collaborative Research: Regulation of the C4-CO2 Concentrating Mechanism in Marine Diatoms by CO2, Light and Nutrients

最近发表的工作提供了证据表明，海洋硅藻使用C4途径通过光合作用（即基于4-碳中间化合物，而不是基于3-碳中间物的C3途径）浓缩二氧化碳（CO2）。本项目的目标是研究这种机制在海洋硅藻光合固碳适应低CO2中的作用，以及光和营养限制对这种适应的调节。实验室实验将侧重于量化C4基因转录丰度和酶活性在短期实验和光暗周期和光和氮限制的模式硅藻物种的文化。实地工作将集中在检查的C4浓缩机制的重要性和它的调节CO2在上升流地区的特点是自然广泛的CO2浓度的俄勒冈州海岸。现场实验的方法将是测量的敏感性，光合作用的碳固定在天然硅藻种群的C4酶的抑制，在原位和操作浓度的CO2。二氧化碳（CO2）对海洋硅藻碳固定的调节以及光和营养物质对CO2控制的调节可能影响海洋生产力、表层沃茨的生物碳输出以及硅藻对全球碳循环的贡献和浮游植物物种组成。 这项研究的结果将是感兴趣的海洋学家研究初级生产和生物碳泵的控制，地球化学家有兴趣在硅藻有机物中使用稳定的碳同位素，以了解当前和历史的生产力和气候变化，以及海洋生态学家感兴趣的浮游植物群落的结构和演变。该项目将支持和培训一名研究生，并为本科生提供研究机会。 研究人员还将把NSF资助的RIOS暑期实习项目的本科生纳入该项目，并将支持新成立的大西洋中部海洋科学教育卓越中心的公共宣传和教育工作。

Recent published work presented evidence that marine diatoms use a C4 pathway to concentrate carbon dioxide (CO2) for fixation through photosynthesis (i.e. based on 4-carbon intermediate compounds, as opposed to a C3 pathway based on 3-carbon intermediates). The goal of this project is to examine the role of this mechanism in the acclimation of photosynthetic carbon fixation in marine diatoms to low CO2, and the modulation of this acclimation by light and nutrient limitation. Laboratory experiments will focus on quantifying C4 gene transcript abundances and enzyme activities in short-term experiments and in light-dark cycle and light- and nitrogen-limited cultures of model diatom species. Fieldwork will focus on examining the importance of the C4 concentrating mechanism and its regulation by CO2 in an upwelling region off the coast of Oregon characterized by a naturally wide range of CO2 concentrations. The field experimental approach will be to measure the sensitivities of photosynthetic carbon fixation in natural diatom populations to the inhibition of C4 enzymes, in relation to in situ and manipulated concentrations of CO2. The regulation of carbon fixation in marine diatoms by carbon dioxide (CO2) and the modulation of CO2 control by light and nutrients may affect ocean productivity, biological carbon export from surface waters and therefore the contribution of diatoms to global carbon cycling, and phytoplankton species composition. The results of this research will be of interest to oceanographers studying the controls of primary production and the biological carbon pump, geochemists interested in the use of stable carbon isotopes in diatom organic matter to understand current and historic productivity and climate change, and marine ecologists interested in the structure and evolution of phytoplankton communities. The project will support and train a graduate student as well as provide research opportunities for undergraduates. The researchers will also incorporate undergraduate students from the NSF-funded RIOS summer internship program into this project and will support the public outreach and education efforts of the newly established Mid-Atlantic Center for Ocean Science Education Excellence.