DISSERTATION RESEARCH: An Ecophysiological Approach to Understanding Macroalgal Nitrate Metabolism and Photosynthesis

论文研究：了解硝酸盐代谢和光合作用的生态生理学方法Timothy谢尔曼和Julien Lartigue所有植物，尤其是水生植物，在养分和光照的可用性方面都会随时间变化。 因此，许多植物似乎已经进化出调节新陈代谢的能力，以应对这些波动。 植物如何调节其光合和养分同化途径以适应环境条件并整合这两个基本过程是本研究的重点。 大型藻类的三个世界性属--浒苔属（绿藻门）、江蓠属（红藻门）和石花菜属（红藻门）--将作为这项工作的植物模型。 本研究的目标是：1）了解光照和硝酸盐可用性的非同步波动如何影响硝酸盐代谢; 2）开发一个预测田间硝酸盐还原速率的模型。 硝酸盐的命运，从吸收到同化，将使用稳定同位素N15进行跟踪，而脉冲幅度调制（PAM）荧光测定法将允许对光合作用途径进行重复的非侵入性采样。 这种综合方法将导致硝酸盐代谢和光合作用的生理学在植物的物理和化学环境的背景下的联系。 其结果将是在整个生物体水平上对大型藻类生理学的更完整的描述。这项工作还旨在通过将这项研究的各个方面纳入海洋植物学课程，将研究与本科教育结合起来。

DISSERTATION RESEARCH: An Ecophysiological Approach to Understanding Nitrate Metabolism and PhotosynthesisTimothy Sherman and Julien LartigueAll plants and especially aquatic plants are subject to temporal variation in the availability of nutrients and light. As a consequence, many plants appear to have evolved a capacity to regulate their metabolism in response to these fluctuations. How plants tune their photosynthetic and nutrient assimilation pathways to the ambient conditions and integrate these two fundamental processes is the focus of this research. Three cosmopolitan genera of macroalgae - Enteromorpha (Chlorophyta), Gracilaria (Rhodophyta), and Gelidium (Rhodophyta) - will serve as the plant models for this work. The goals of this research are 1) to understand how non-synchronous fluctuations in light and nitrate availability influence nitrate metabolism and 2) to develop a model for predicting rates of nitrate reduction in the field. The fate of nitrate, from uptake to assimilation, will be tracked using the stable isotope, N15, while pulse amplitude modulated (PAM) fluorometry will allow for repeated, non-invasive sampling of photosynthetic pathways. This integrative approach will lead to a linking of the physiology of nitrate metabolism and photosynthesis in the context of a plant's physical and chemical surroundings. The result will be a more complete picture of macroalgal physiology at the level of the whole organism. This work also seeks to integrate research with undergraduate education by including aspects of this research in a marine botany course.