EAGER: Assessment of Pseudo-nitzschia ferritin gene expression as a molecular indicator of iron nutritional status along natural iron gradients

EAGER：评估伪菱形藻铁蛋白基因表达作为沿天然铁梯度的铁营养状况的分子指标

• 批准号: 0946260
• 负责人: Virginia Armbrust
• 金额: $ 12.38万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2011-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0946260&HistoricalAwards=false
• 关键词: EAGER; Assessment; Pseudo; nitzschia; ferritin

Iron availability limits productivity in 30-40% of the world's oceans. Microbes that persist in these regions must be able to rapidly take up and store iron when it is available and withstand long intervals of limited iron supply. Ferritins are highly specialized iron storage proteins present in many animals, plants and microorganisms. The investigators recently discovered that marine pennate diatoms possess ferritin and showed that iron availability was directly related to ferritin transcript abundance in both oceanic and coastal species of the cosmopolitan pennate diatom genus Pseudonitzschia. Whole genome sequence analysis indicated that ferritin is not present within the centric species, Thalassiosira pseudonana and the oceanic species P. granii underwent more cell divisions based on stored iron than an oceanic species of Thalassiosira. Based on these results, the investigators hypothesized that increased iron storage via ferritin provides a competitive advantage to pennate diatoms in low-iron environments that receive intermittent iron inputs and that the activity of ferritin underlies their dominance in oceanic iron fertilization experiments. This project relies on a combination of field and laboratory samples to test the hypothesis that transcript abundance of the ferritin gene (FTN) reflects the iron status of natural communities of the diatom Pseudonitzschia. First, they will utilize field samples collected from a natural iron gradien and from an iron grow-out microcosm experiment at a well-characterized iron-limited region, Ocean Station Papa. P. granii was abundant at all sampled sites, as well as in the iron-induced bloom and will serve as the target organism. Second, P. granii strains isolated from OSP will be investigated under controlled laboratory conditions to confirm that the transcript abundance of FTN is influenced by iron nutritional status and not other environmental parameters. This research is a good fit for support through the EAGER program as there is the potential for the development of a new molecular tool to elucidate the iron status of phytoplankton in the field but there is an urgent and limited time frame in which this research can be performed. The research will serve as a proof of principle study to verify the importance of pennate diatom ferritin and iron storage as a selective mechanism controlling the distributions of this ecologically important group.The outcome of the research will be development of a Pseudonitzschia Ferritin Index (PFI) that can be used by other research groups interested in assessing the iron nutritional status of natural mixed phytoplankton communities. Iron measurements are complicated by the diversity of compounds that complex iron present within field samples, potentially lowering the biological availability of iron. Development of the index will obviate these potential complications and would serve as a biologically relevant indicator of iron availability. Each year, six to seven undergraduates are given opportunities to conduct research in the Armbrust lab. Dr. Marchetti, an early career scientist, will continue to mentor an undergraduate to help with this project. All undergraduates have the opportunity to present their research at the Annual Undergraduate Research Symposium held each year at the University of Washington.

铁的可用性限制了世界海洋30-40％的生产率。在这些区域中持续存在的微生物必须能够在可用时快速占用并存储铁，并承受铁供应有限的长时间。铁蛋白是许多动物，植物和微生物中存在的高度专业铁储存蛋白。研究人员最近发现，海洋倾斜的硅藻具有铁蛋白，并表明铁的可用性与国际化pennate Diotom pseudonitzschia的海洋和沿海物种中的铁蛋白转录物丰度直接相关。整个基因组序列分析表明，在中心物种，thalassiosira pseudonana和海洋物种中，铁蛋白不存在于储存的铁中比thalassiosira的海洋种类多的细胞分裂。基于这些结果，研究人员假设通过铁蛋白增加铁储存的储存为低铁环境中的pennate硅藻提供了竞争优势，而低铁环境接收间歇性铁输入，而铁蛋白的活性则是其在海洋铁施肥实验中的优势。该项目依靠现场和实验室样品的组合来检验以下假设：铁蛋白基因（FTN）的转录物丰度反映了硅藻pseudonitzschia的自然群落的铁地位。首先，他们将利用从天然铁毕业生中收集的田间样品，以及从特征良好的铁限制区域的海洋站爸爸的铁长大的缩影实验。格拉尼疟原虫在所有采样的地点以及铁诱导的花朵中都很丰富，并将用作目标生物。其次，将在受控的实验室条件下研究从OSP中分离出来的格拉尼菌株，以确认FTN的转录丰度受到铁营养状况的影响，而不是其他环境参数。这项研究非常适合通过急切的计划提供支持，因为有可能开发一种新的分子工具来阐明该领域的浮游植物的铁状态，但是有一个紧急且有限的时间范围，可以进行这项研究。 The research will serve as a proof of principle study to verify the importance of pennate diatom ferritin and iron storage as a selective mechanism controlling the distributions of this ecologically important group.The outcome of the research will be development of a Pseudonitzschia Ferritin Index (PFI) that can be used by other research groups interested in assessing the iron nutritional status of natural mixed phytoplankton communities.铁的测量结果是复杂的，这些化合物的多种化合物在田间样品中存在复杂的铁，从而有可能降低铁的生物利用率。该指数的发展将消除这些潜在的并发症，并将作为铁可用性的生物学相关指标。每年，有六到七名本科生都有机会在Armbrust Lab进行研究。早期职业科学家Marchetti博士将继续指导本科生，以帮助该项目。所有的本科生都有机会在每年在华盛顿大学举行的年度本科研究研讨会上介绍他们的研究。