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

这个项目的重点是一组重要的光合藻类，硅藻，以及铁的可用性如何调节它们的生长。硅藻是海洋食物网的重要基础生物。硅藻生长所必需的蛋白质的结构和功能都需要铁。在海洋的许多地区，铁的浓度可能很低，并根据大小和化学特征以不同的形式存在。最近的努力增加了对这些不同铁形态分布的了解，但个别浮游植物可以获得哪些形态仍不清楚。研究人员将对重要的硅藻物种进行实验，以开发和使用分析方法，以评估这些物种是否可以通过不同形式或不同来源获得铁，以减轻铁应激。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，这将证明对气候和食物网建模者是有价值的。该项目将进一步实现国家科学基金会培养新一代科学家和使科学发现向公众开放的目标。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。该项目结合痕量金属生物地球化学、浮游植物培养和分子生物学来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素。虽然由于GEOTRACES项目的开展，人们对铁元素分布的了解大大增加，但对各种形式铁元素生物利用度的机制和定量了解仍然模糊不清。此前，研究人员开发了一种校准的分子生物测定方法，能够指示特定的海洋硅藻何时经历铁胁迫。它已被用于评价海洋场样品和孵育样品中不同铁组分添加的铁应力。本提案的目标是为来自沿海和海洋栖息地的其他环境相关硅藻的铁胁迫开发额外的校准分子测定方法，并利用它们来评估来自不同来源的铁的生物可利用性。实验计划包括生长监测、光合生理和铁胁迫反应基因表达的培养实验。然后，分子分析将用于测试来自各种来源的铁是否可以缓解不同物种的铁应激。这个项目的结果将提供工具来回答关于各种形式的铁对重要浮游植物的生物可利用性的基本问题。因此，这项研究将为生物地球化学建模者提供有价值的信息，提高他们使用GEOTRACES程序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.