OCE-RIG: Developing Molecular Bioassays for Evaluating Iron Status of Environmentally Relevant Diatoms

该项目的重点是光合藻类的一个重要群体，硅藻，以及铁的可用性如何调节它们的生长。硅藻是海洋食物网基础的重要生物。铁是硅藻生长所必需的蛋白质的结构和功能所必需的。在海洋的许多地区，铁的浓度可能很低，并以不同的形式存在，按大小和化学特性分类。最近的努力增加了对这些不同铁形式分布的了解，但个体浮游植物可以获得的形式仍然不清楚。研究人员将对重要的硅藻物种进行实验，以开发和使用可以评估这些物种是否可以获得以不同形式或不同来源提供的铁以缓解铁压力的测定方法。这些数据将帮助我们了解铁与食物网基础上的一组重要生物之间的关系，这将对气候和食物网建模者有价值。该项目将进一步推动NSF培养新一代科学家和向公众提供科学发现的目标。该项目支持一名早期职业科学家的研究，培训本科生和高中生，包括市中心的初中和高中女生。该项目结合了痕量金属地球化学、浮游植物培养和分子生物学，以解决各种铁形式对环境相关硅藻的生物利用度问题。铁是海洋浮游植物必需的微量营养元素。虽然由于正在进行的GEOTRACES计划，铁的分布知识显着增加，但对各种形式铁的生物利用度的机械和定量理解仍然是虚幻的。此前，研究人员开发了一种校准的分子生物测定法，能够指示特定的海洋硅藻何时经历铁胁迫。它已被用来评估在海洋领域的样品和孵化样品中的铁应力，以响应添加不同的铁馏分。该提案的目标是开发其他校准分子测定法，用于测定沿海和海洋生境中其他与环境相关的硅藻的铁胁迫，并利用这些测定法评估不同来源铁的生物可利用性。实验计划包括培养实验监测生长，光合生理，和铁胁迫响应基因的基因表达。然后将使用分子测定来测试来自各种来源的铁是否可以缓解不同物种的铁胁迫。该项目的结果将提供工具来回答有关各种形式的铁对重要浮游植物的生物利用度的基本问题。因此，这项研究将为海洋地球化学建模者提供有价值的信息，提高他们使用GEOTRACES计划生成的数据准确预测海洋生产力未来变化的能力。

This project focuses on an important group of photosynthetic algae, the diatoms, and how iron availability modulates their growth. Diatoms are important organisms at the base of the marine food web. Iron is required for the structure and function of proteins essential to diatom growth. Iron concentrations can be low in many areas of the ocean and exists in different forms classified by size and chemical characteristics. Recent efforts have increased understanding of the distribution of these different iron forms, but which forms individual phytoplankton can access remains unclear. The investigator will conduct experiments with important diatom species to develop and use assays that can assess whether iron provided in different forms or from different sources can be accessed by those species to alleviate iron stress. These data will help us understand the relationship between iron and an important group of organisms at the base of the food web, which will prove valuable to climate and food web modelers. This project will further the NSF goals of training new generations of scientists and making scientific discoveries available to the general public. The project supports the research of an early-career scientist, the training of undergraduate and high school students, including inner city middle and high school girls.The project combines trace metal biogeochemistry, phytoplankton cultivation, and molecular biology to address questions about the bioavailability of various iron forms to environmentally relevant diatoms. Iron is an essential micronutrient for marine phytoplankton. While knowledge of the distribution of iron has increased significantly as a result of the ongoing GEOTRACES program, a mechanistic and quantitative understanding of the bioavailability of various forms of iron remains illusive. Previously, the investigator developed a calibrated molecular bioassay capable of indicating when a specific oceanic diatom was experiencing iron stress. It has been used to evaluate iron stress in oceanic field samples and in incubation samples in response to additions of different iron fractions. The goal of this proposal is to develop additional calibrated molecular assays for iron stress in other environmentally relevant diatoms from both coastal and oceanic habitats and use them to asses the biological availability of iron from varying sources. The experimental plan includes culture experiments monitoring growth, photosynthetic physiology, and gene expression of iron stress response genes. The molecular assays will then be used to test whether iron from a variety of sources can alleviate iron stress in the different species. Results from this project will provide tools to answer fundamental questions about the bioavailability of various forms of iron to important phytoplankton. As such, this research will provide valuable information for biogeochemical modelers, increasing their ability to use the data generated from the GEOTRACES program to accurately predict future changes in ocean productivity.