Physiology, Ecology and Biochemistry of Nitrogen Fixation byMarine Planktonic Microorganisms

卡彭特博士和卡彭博士建议继续他们的 生物化学、生理学和生态学的研究 固氮微生物中的N2固定，特别是 非异形胞蓝藻束毛藻属。 这些研究 是重要的，因为束毛藻是 热带和亚热带海域的浮游植物种群 也是这些系统中新氮的主要贡献者。 此外，束毛孢固氮酶系统 似乎在几个方面不同于更好地研究 非异形胞类似物。 的理解 生物化学和分子机制， 保持活跃的固氮作用将具有广泛的相关性。 他们将决定因素（生物化学和生态） 也调节束毛藻的固氮和生长， 在海洋食物网中的重要性。 具体来说，他们 将继续研究：1）保护机制 氧失活固氮酶（氧保护酶 系统如超氧化物歧化酶、摄取氢化酶 等）; 2)控制表观内源性节律的因素 固氮酶的合成和活性， 固氮酶的合成和活性，ATP/ADP比率）; 3）如何 固定氮在固氮和不固氮之间转移 4）细胞周期的原因及意义 浮力的变化; 5）氮和碳的命运 最近被束毛藻固定在近地表沃茨。 这项研究计划是独一无二的，因为它汇集了一个 不同的调查小组，以广泛的工作， 关于束毛藻属的生物学和生态学的专题， 其他海洋固氮生物

Drs. Carpenter and Capone propose to continue their investigations of the biochemistry, physiology and ecology of N2 fixation in planktonic microorganisms, and particularly the non-heterocystous cyanobacterium Trichodesmium. These studies are important as Trichodesmium is a substantial component of the phytoplankton populations of tropical and subtropical seas and a major contributor of new nitrogen to these systems. Furthermore, the nitrogenase enzyme system of Trichodesmium appears distinct in several respects from the more well studied non-heterocystous analogues. An understanding of the biochemical and molecular mechanisms used by Trichodesmium to maintain active nitrogen fixation would be of broad relevance. They will determine the factors (biochemical and ecological) which regulate N2 fixation and growth in Trichodesmium, as well as its importance in the marine food web. Specifically, they will pursue studies of: 1) the mechanisms for protecting nitrogenase from oxygen deactivation (oxygen protective enzyme systems such as superoxide dismutase, uptake hydrogenases etc.); 2) factors controlling the apparent endogenous rhythms of nitrogenase synthesis and activity, and of regulation of nitrogenase synthesis and activity, ATP/ADP ratios); 3) how fixed nitrogen is transferred between N2 fixing and non-fixing cells within a colony; 4) the causes and significance of diel changes in buoyancy; and 5) the fate of nitrogen and carbon recently fixed by Trichodesmium in near surface waters. This research program is unique in that it brings together a diverse group of investigators to work on a broad array of topics concerning the biology and ecology of Trichodesmium and other open ocean nitrogen fixers.