Structural variation of the nitrogen-fixing heterocyst: Addressing the role of gas permeability in evolutionary divergence

微生物对氮的固定每年为自然和农业系统贡献了大量可用的、维持生命的氮。由于氧气不可逆转地毒害固氮机制，管理氧气暴露是固氮生物体的中心问题，它们利用氧气来制造能量。蓝藻异形胞是一种特殊的细胞，旨在为固氮提供足够的能量和有利的环境。在这里，研究人员建议使用杂胞体作为一个模型，以解决温度变化如何塑造生物结构的形式和功能，生物结构操纵与环境的气体交换。具体地说，研究人员将结合化学、生理和遗传方法来测试与环境温度相关的杂胞体结构的自然变化如何通过改变进入杂胞体的氧气来影响杂胞体功能的温度依赖性。该项目承诺对这一在生态和经济上具有重要意义的结构如何受到气温上升的影响，以及它在面对环境变化时的进化反应能力，提供新的和一般的见解。由于杂胞体也是目前利用光能生产氢能的最佳模型，该项目的结果将对如何设计一种可靠且负担得起的氢源产生影响。该项目通过不同层次的指导和推广，将研究和教育结合在一起，包括在黄石公园举办的实地课程，揭示了在世界上第一个国家公园控制氮有效性的微生物和野生动物之间的相互依存关系。

Nitrogen (N) fixation by microorganisms contributes enormous quantities of usable, life-sustaining N to natural and agricultural systems each year. Because oxygen irreversibly poisons the N-fixation machinery, managing oxygen exposure is a central problem for N-fixing organisms, which use oxygen to make energy. The cyanobacterial heterocyst is a specialized cell designed to provide both sufficient energy and an environment favorable for N fixation. Here, the investigators propose to use the heterocyst as a model to address how changing temperature shapes the form and function of biological structures, which manipulate gas exchange with the environment. Specifically, the investigators will combine chemical, physiological, and genetic approaches to test how naturally-occurring variation in heterocyst architecture associated with environmental temperature impacts the temperature-dependence of heterocyst function through the modification of oxygen flow into the heterocyst. The project promises novel and general insights into how this ecologically and economically important structure is affected by increasing temperature and its capacity for an evolutionary response in the face of environmental change. Because the heterocyst is also currently the best model for producing hydrogen energy from light, the project outcomes will have implications for how to engineer a reliable and affordable source of hydrogen. The project integrates research and education through mentoring and outreach at diverse levels, including a field course in Yellowstone that reveals the interdependence of microorganisms and wildlife for controlling N availability in the world's first national park.