Collaborative Research: The Effect of Iron Bioavailability on Synechococcus Diversity from a HNLC Regime to the Costa Rica Upwelling Dome

在地球上，来自海洋的二氧化碳的光合固定约占全球初级生产总量的一半。 在中央海洋环流中，数量最多的光合生物是微微型浮游生物、聚球藻和原绿球藻。 最近，它已被证明，这些人口组成的许多密切相关，但遗传不同的生态型。 迄今为止，在聚球藻的十多个分支中，只有少数分支与表型相关，而区分其余分支的因素尚不清楚。 这些研究人员假设，微量金属铁（Fe）的生物利用度是推动该属分化的重要因素。 了解铁是否以及何时限制聚球藻生产力以及这种限制如何调节聚球藻群落结构将增加我们对这种重要微量元素如何影响海洋生物地球化学循环以及介导其中一些循环的生物多样性的理解。 本项目：1）正在开发海洋聚球藻的全细胞标记Fe胁迫测定，2）正在使用全细胞标记结合流式细胞术来探测聚球藻群落的Fe胁迫，以将受胁迫的细胞从东太平洋通过贫营养和高营养低叶绿素（HNLC）制度到哥斯达黎加上升流圆顶的断面上的充满细胞中分选出来，3）使用群落指纹法检查沿着样带的聚球藻的遗传多样性，并确定Fe胁迫或Fe充足的细胞的遗传进化枝，以及4）从贫营养的HNLC分离海洋聚球藻的新菌株，和哥斯达黎加上升流制度，并表征其生育和铁生理。该项目正在利用现有的巡航机会前往哥斯达黎加上升流穹，据报告，那里的聚球藻浓度非常高（106/ml）。 现有的辅助数据的微量金属浓度和形态提供了一个前所未有的机会，研究如何相互作用的多种微量金属（铁，钴，铜，锌，镉）有助于保持遗传多样性，在这些picoconferters。 该项目正在培训两名研究生和几名本科生研究员。 资金允许其中一些学生参加全国会议。 在小型学院中，优先考虑来自代表性不足群体的学生。

On Earth, photosynthetic fixation of CO2 from the oceans accounts for approximately half of total global primary production. In the central oceanic gyres the most numerous photosynthetic organisms are the picoplankton, Synechococcus and Prochlorococcus. Recently it has been shown that these populations consist of numerous closely related but genetically distinct ecotypes. Of the more than ten clades of Synechococcus identified to date, only a few have been associated with a phenotype, while the factors differentiating the remaining clades are not yet understood. These investigators hypothesize that the bioavailability of the trace metal iron (Fe) is an important factor driving the differentiation in this genus. Understanding if and when Fe is limiting Synechococcus productivity and how this limitation modulates Synechococcus community structure will increase our understanding of how this important trace element impacts oceanic biogeochemical cycles and the diversity of the organisms mediating some of these cycles. This project: 1) is developing a whole cell labeling Fe stress assay for marine Synechococcus,, 2) is probing the Synechococcus community for Fe stress using whole cell labeling coupled with flow cytometry to sort the stressed cells from the replete cells on a transect in the Eastern Pacific through oligotrophic and high nutrient low chlorophyll (HNLC) regimes to the Costa Rica upwelling dome, 3) is examining the genetic diversity of Synechococcus along the transect using community fingerprinting methods and determining the genetic clade of the cells that are Fe-stressed or Fe replete and 4) isolating new strains of marine Synechococcus from oligotrophic, HNLC, and Costa Rica upwelling regimes and characterize their phylogeny and Fe physiology. This project is taking advantage of existing cruise opportunities to the Costa Rica upwelling dome (CRD), where remarkably high concentrations (106/ml) of Synechococcus have been reported. Available ancillary data on both trace metal concentrations and speciation is providing an unprecedented opportunity to examine how the interplay of multiple trace metals (Fe, Co, Cu, Zn, Cd) is contributing to maintaining genetic diversity in these picoplankters. This project is training two graduate students and several undergraduate research fellows. Funds are allowing some of these students to attend national meetings. Priority is being given to students from under-represented groups at small colleges.