Regulation of the Genes Encoding the Mo-nitrogenase in Anabaena

蓝藻是生活在不同栖息地的重要生物。它们从阳光中获取能量，从空气中的二氧化碳中获取碳，从空气中的氮气中获取氮。它们不仅是自由生活的有机体，而且在与植物和真菌的许多共生关系中也是重要的伙伴。水藻是一种蓝藻，它具有通过固氮过程将空气中的氮气转化为肥料的能力。水蓝藻是研究得最好的蓝藻之一，它在光照下进行光合作用，消耗温室气体二氧化碳，它可以在黑暗中生长，利用糖作为碳和能量来源。它与硝酸盐或氨等氮源一起生长得很好，但它也能将大气中的氮转化为氨，这是一种植物可以利用的形式。除了氨，酶氮酶自然产生氢，一种替代能源，和水藻已被用于生产氢气在室外生物反应器。这种将大气中的氮转化为氨和氢的过程发生在一种叫做异囊的特殊细胞中，这种细胞含有必要的酶——氮酶。环境因素控制水藻异囊分化、固氮和产氢的机制尚不清楚。对于固定氮所需的重要基因，尤其是固氮酶的表达控制，我们知之甚少。本研究项目的目的是利用遗传学工具更好地了解水藻中氮酶基因表达控制的分子机制。这项研究的意义在于，它可以提高氮酶活性，可用于生物肥料生产。氮酶活性的增加也会导致鱼腥鱼产氢量的增加。因此，这项研究有可能减少对化肥商业生产中化石燃料消耗的依赖，并提供氢，氢可以在配备燃料电池的汽车中替代汽油。这个研究项目与教育紧密结合在一起。一个由十几名本科生组成的多元化小组将为研究项目做出贡献，作为一个结构化的本科生研究课程的一部分，该课程每周在教学实验室举行两个下午的会议。这门课程之前已经教授过，它将合作研究与生物信息学活动、科学写作技能的发展以及在大学本科生研究研讨会上的研究报告结合起来。其他本科生、研究生和博士后也将直接参与该项目，在研究实验室工作。他们将在寻求更好地理解异囊中氮酶基因表达调控的工作方面进行合作。研究小组成员还将参加教育外展活动，特别是针对大学预科教师，以增加他们对一般科学，特别是微生物学的理解。这些活动包括开发适合课堂的实践活动，并在圣路易斯地区的教师夏季讲习班上介绍这些材料。这些活动构成了通过互联网免费分发的教育材料的基础。

Cyanobacteria are important organisms that live in diverse habitats. They get their energy from sunlight, their carbon from carbon dioxide in the air, and their nitrogen from the nitrogen gas in the air. They are important not only as free-living organisms, but also as partners in many symbiotic associations with plants and fungi. Anabaena is a cyanobacterium of great interest for its ability to convert nitrogen gas in the air to fertilizer by a process called nitrogen fixation. Anabaena, one of the best studied cyanobacteria, grows photosynthetically in the light, consuming the greenhouse gas, carbon dioxide, and it can grow in the dark using sugar as both a carbon and energy source. It grows well with nitrogen sources such as nitrate or ammonia, but it can also convert atmospheric nitrogen to ammonia, a form usable by plants. In addition to ammonia, the enzyme nitrogenase naturally produces hydrogen, an alternative energy source, and Anabaena has been used for the production of hydrogen in outdoor bioreactors. This conversion of atmospheric nitrogen to ammonia and hydrogen takes place in specialized cells called heterocysts, which contain the necessary enzyme, nitrogenase. The mechanism by which environmental factors control heterocyst differentiation, nitrogen fixation, and hydrogen production in Anabaena is poorly understood. Little is known about the control of expression of the important genes, especially nitrogenase, that are required to fix nitrogen. The goal of this research project is to use genetic tools to better understand the molecular mechanisms by which expression of nitrogenase genes is controlled in Anabaena. The significance of this research is that it can lead to increased nitrogenase activity that could be used for biological fertilizer production. Increased nitrogenase activity would also lead to increased hydrogen production in Anabaena. Thus, this research has the potential to decrease reliance on fossil fuel consumption in the commercial production of fertilizer and to provide hydrogen, which can be used an alternative to gasoline in cars equipped with fuel cells. This research project is heavily integrated with education. A diverse group of about a dozen undergraduate students will contribute to the research project as part of a structured undergraduate research course that meets two afternoons a week in a teaching laboratory. The course, which has been taught previously, integrates collaborative research with bioinformatics activities, the development of scientific writing skills, and the presentation of the research at the university's Undergraduate Research Symposium. Additional undergraduate research students, graduate students and a postdoctoral fellow will be also be directly involved in the project, working in the research lab. They will work collaboratively on aspects of the work that seek to better understand the regulation of nitrogenase gene expression in heterocysts. Members of the research team will also participate in education outreach activities, especially focused on precollege teachers, to increase their understanding of science in general and microbiology in particular. These activities include development of hand-on activities suitable for the classroom and presentations of these materials at summer workshops for teachers in the St. Louis region. These activities form the basis for educational materials that are distributed freely via the internet.