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上30-40%海洋的生产力。在这些区域持续存在的微生物必须能够在铁可用时快速吸收和储存铁，并承受长时间的有限铁供应。铁蛋白是存在于许多动物、植物和微生物中的高度特化的铁储存蛋白。研究人员最近发现，海洋羽状硅藻具有铁蛋白，并表明铁的可用性与海洋和沿海物种的世界性羽状硅藻属Pseudonitzschia的铁蛋白转录本丰度直接相关。全基因组序列分析表明，铁蛋白不存在于中心物种，海链藻和海洋物种P. granii经历了更多的细胞分裂的基础上存储的铁比海洋物种海链藻。基于这些结果，研究人员假设，通过铁蛋白增加的铁储存为在接受间歇性铁输入的低铁环境中的羽状硅藻提供了竞争优势，并且铁蛋白的活性是它们在海洋铁施肥实验中占主导地位的基础。该项目依赖于现场和实验室样品的组合来测试铁蛋白基因（FTN）的转录丰度反映硅藻Pseudonitzschia的自然群落的铁状态的假设。首先，他们将利用从天然铁梯度和在一个特征良好的铁有限区域海洋站Papa进行的铁生长微观实验中收集的实地样本。在所有采样点，以及在铁诱导的水华中，P. granii都很丰富，将作为目标生物。其次，将在受控的实验室条件下研究从OSP分离的P. granii菌株，以确认FTN的转录物丰度受铁营养状况而不是其他环境参数的影响。这项研究非常适合通过EAGER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浮游植物的铁状况，但这项研究的时间紧迫且有限。这项研究将作为一个原理研究的证据，以验证羽状硅藻铁蛋白和铁储存的重要性，作为一个选择性的机制控制这一重要的生态群体的分布。研究的结果将是一个伪菱形铁蛋白指数（PFI），可用于其他研究小组有兴趣在评估自然混合浮游植物群落的铁营养状况的发展。铁的测量是复杂的化合物的多样性，复杂的铁存在于现场样品，潜在地降低铁的生物利用度。该指数的开发将排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有机会在Armbrust实验室进行研究。马切蒂，一个早期的职业科学家，将继续指导本科生，以帮助这个项目。所有本科生都有机会在每年在华盛顿大学举行的年度本科生研究研讨会上展示他们的研究。