Collaborative Research: Investigating the Ecological Importance of Iron Storage in Diatoms

合作研究：调查硅藻铁储存的生态重要性

• 批准号: 1334632
• 负责人: Benjamin Twining
• 金额: $ 35.27万
• 依托单位: Bigelow Laboratory for Ocean Sciences
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1334632&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Ecological; Importance

Diatoms are responsible for a significant fraction of primary production in the ocean. They are associated with enhanced carbon export and usually dominate the response of phytoplankton to additions of the micronutrient iron in high-nutrient, low-chlorophyll (HNLC) regions. Diatoms, particularly those isolated from the open ocean, appear to have a significant capacity to store iron for later use, and in some groups of diatoms this ability is enabled by the iron storage protein ferritin. Such luxury uptake of iron has long been observed in laboratory cultures and hypothesized to provide diatoms with an ecological benefit in the low-iron waters that cover 40% of the global ocean. However iron storage has been difficult to observe in natural systems due to the methodological challenges of working with mixed plankton assemblages, and a physiological understanding of the impacts of iron on ocean diatoms is lacking. This project combines state-of-the-art high-throughput transcriptomic sequencing and single-cell element analysis with novel laboratory and field incubation experiments to quantify iron storage abilities of cultured and natural diatoms that either contain or lack ferritin and determine the ecological impacts of this process. The overall objective of this project is to examine the ecological importance of iron storage as a selective mechanism controlling the distributions of diatoms along iron gradients in marine ecosystems. The proposed research includes three specific objectives:A. Determine if there is a consistent physiological difference in the ability of pennate versus centric diatoms to store iron.B. Examine whether iron storage capacities across diverse diatom taxa consistently provide a mechanistic explanation for continued growth in the absence of iron.C. Determine whether enhanced iron storage provides diatoms with a competitive within natural phytoplankton assemblages in both coastal and oceanic regions.Transcriptomic sequencing on a variety of ecologically important pennate and centric diatoms will be used to survey for the presence of ferritin-like genes in order to establish biogeographical and/or phylogenetic patterns of occurrence of diatom ferritin. Laboratory culture experiments will be used to quantify the iron storage abilities of these diatoms, as well as the number of cell divisions that can be supported by the stored iron, providing valuable physiological data to inform the understanding of plankton ecology in iron-limited coastal and HNLC systems. The laboratory experiments will be complemented by measurements of ferritin expression and iron storage in coastal and ocean diatoms sampled across gradients of iron availability on two cruises-of-opportunity to the northeast Pacific Ocean.Intellectual Merit: By characterizing the diversity in potential iron storage capacities of diatoms and elucidating the role ferritins play in enhancing iron storage and the iron-limitation response, this project will provide new insights into how this important group of primary producers has adapted to their environment, thus contributing to our knowledge of what factors influence their abundance and distributions. This knowledge is especially important in relation to predicting the future effects of climate change on these organisms that are responsible for significant primary production in marine ecosystems.Broader Impacts: This project incorporates several activities that will directly contribute to education and training. The training of a graduate student, post-doctoral researcher and multiple undergraduates will be directly supported. Additionally, a broader impact goal of this project is to facilitate teaching and learning on marine science-related topics through translating our research objectives into widely distributed educational materials that can be used in the classroom. To accomplish this, a high-school teacher will participate in one of the cruises and convey her experiences at sea to her students as well as develop curricular materials for her class. These will be used for high-school earth and environmental science courses and also distributed to teachers in Maine as part of Bigelow Laboratories teacher training program, thus broadening the scope of the outreach activities.

硅藻是海洋中主要产量的很大一部分。它们与增强的碳输出有关，通常主导浮游植物对高氮，低氯易植物（HNLC）区域中微量营养素的添加的反应。硅藻，尤其是那些从开阔的海洋中分离出来的硅藻，似乎具有储存铁供以后使用的重要能力，在某些硅藻中，这种能力由铁储存蛋白铁蛋白启用。长期以来，在实验室培养物中观察到了这种豪华摄取，并假设在覆盖全球海洋40％的低铁水中为硅藻提供了生态益处。然而，由于缺乏对铁对铁对海洋硅藻的影响的生理理解，因此由于方法学的挑战，在天然系统中很难观察到铁的储存。该项目结合了最新的高通量转录组测序和单细胞元素分析与新型实验室和现场孵育实验，以量化含有或缺乏铁蛋白的培养的培养和自然硅藻的储存能力，并确定该过程的生态影响。该项目的总体目的是研究铁储存的生态重要性，作为控制硅藻生态系统中铁梯度分布的选择性机制。拟议的研究包括三个具体目标：确定甲酸盐与中心硅藻储存铁的能力是否存在一致的生理差异。检查各种硅藻类群的铁储能是否始终如一地提供了在没有铁的情况下持续增长的机械解释。确定在沿海和海洋区域的天然植物浮游生物组合中，增强的铁储存是否提供具有竞争力的硅藻。对各种生态重要的五甲酸盐和中心硅藻进行的转录测序将用于调查是否存在生物地理基因，以建立生物地理位置图。实验室培养实验将用于量化这些硅藻的铁储存能力，以及储存的铁可以支持的细胞分裂数量，提供有价值的生理数据，以告知对铁受限的沿海和HNLC系统中浮游生物生态的理解。实验室实验将通过测量铁蛋白的表达和沿海和海洋中的铁硅化的测量，这些沿海和海洋的硅藻在铁的梯度上取样，在两次向东北太平洋的范围巡游中进行了铁梯度，智能良好的优点：通过表征潜在的diatoms的潜在铁能量，并促进了这种效力的富含铁素的生产效果，并将其提高到层次上，并促进了这一领域的生命力，并促进了这一领域的生命，并富含铁的生命力。这个重要的主要生产者群体如何适应其环境，从而有助于我们了解哪些因素影响其丰度和分布。对于预测气候变化对这些生物的未来影响的影响，这些知识尤为重要，这些生物在海洋生态系统中的重要生产。将直接支持研究生，博士后研究人员和多名本科生的培训。此外，该项目的一个更广泛的影响力是通过将我们的研究目标转化为可以在课堂上使用的广泛分布的教育材料来促进与海洋科学相关的主题的教学。为此，一位高中老师将参加其中一名巡游，并将她在海上的经验传达给学生，并为她的班级开发课程材料。这些将用于高中地球和环境科学课程，并作为Bigelow Laboratories教师培训计划的一部分分发给缅因州的教师，从而扩大了外展活动的范围。