The Genetic Potential for Nitrogen Fixation in the Marine Environment

海洋的初级生产力与自养生长所需的营养物质的生物地球化学循环交织在一起。虽然关于哪些营养物质限制海洋生产力还没有明确的共识，但很明显，主要营养物质氮(N)和磷(P)在少营养海洋环流中以低浓度存在。氮限制的争论一直是复杂的，因为氮缺乏可以通过大气氮的生物还原来缓解。然而，在开阔的海洋中发现的固氮生物很少。鉴定固氮基因的DNA扩增和探针技术的发展是评估环境中固氮潜力的有力工具。最近的进展表明，这种方法可以用于检测N2固定基因的表达，这将进一步发展作为该计划的一部分。本研究的目标将是完成、证实和扩展先前在大西洋和太平洋的物理、化学和生物参数背景下对固氮的研究结论。本研究将回答海洋环境中固氮物种的存在以及限制固氮基因分布和表达的因素。

Zehr 95-03593 The primary productivity of the oceans is intertwined with the biogeochemical cycling of nutrients required for autotrophic growth. Although there is not clear agreement on which nutrients limits ocean productivity, it is evident that the major nutrients nitrogen (N) and phosphorus (P) are present at low concentrations in the oligotrophic ocean gyres. The argument for N limitation has always been complicated by the fact that N deficiency could be alleviated by the biological reduction of atmospheric N2. Yet few N2 fixing organisms have been found in the open ocean. The development of DNA amplification and probe techniques for characterizing N fixation genes are powerful tools for assessing N2 fixation potential in the environment. Recent advances have demonstrated that this approach can be used to assay the expression of N2 fixation genes, which will be developed further as part of this program. The goals of this research will be to complete, substantiate and extend the conclusions from prior studies of N fixation in the context of physical, chemical and biological parameters of the Atlantic and Pacific Oceans. This research will answer the question of the presence of N2 fixing species in the oceanic environment and the factors limiting the distribution and expression of N2 fixation genes.