Regulation of the Genes Encoding the Mo-nitrogenase in Anabaena

蓝藻是生活在不同生境中的重要生物。它们的能量来自阳光，碳来自空气中的二氧化碳，氮气来自空气中的氮气。它们不仅作为自由生活的有机体很重要，而且作为许多与植物和真菌共生的伙伴也很重要。鱼腥藻是一种令人感兴趣的蓝藻，它通过一种名为固氮的过程将空气中的氮气转化为肥料。鱼腥藻是研究最充分的蓝藻之一，它在光下光合作用生长，消耗温室气体二氧化碳，它可以利用糖作为碳和能源在黑暗中生长。它在硝酸盐或氨等氮源中生长良好，但它也可以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，固氮酶自然产生氢气，这是一种替代能源，鱼腥藻已被用于户外生物反应器中的氢气生产。这种将大气中的氮转化为氨和氢的过程是在称为杂胞体的特殊细胞中进行的，杂胞体含有必要的酶--固氮酶。环境因素控制鱼腥藻异形胞分化、固氮和产氢的机制尚不清楚。人们对固氮所需的重要基因，特别是固氮酶的表达调控知之甚少。本研究项目的目的是利用基因工具更好地了解鱼腥藻中固氮酶基因表达的分子机制。本研究的意义在于可以提高固氮酶活性，可用于生物肥料生产。固氮酶活性的提高也会导致鱼腥藻产氢增加。因此，这项研究有可能减少商业化肥生产中对化石燃料消耗的依赖，并提供氢气，氢气可以在配备燃料电池的汽车中用作汽油的替代品。这项研究项目与教育紧密结合。一个由大约12名本科生组成的不同群体将参与这个研究项目，这是一个结构化的本科生研究课程的一部分，该课程每周有两个下午在教学实验室举行。这门课程以前已经教授过，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在一起。更多的本科生、研究生和一名博士后也将直接参与该项目，在研究实验室工作。他们将在这项工作的各个方面进行合作，寻求更好地了解异形囊中固氮酶基因表达的调节。研究小组的成员还将参加教育推广活动，特别是以大学预科教师为重点的教育活动，以增加他们对一般科学，特别是微生物学的了解。这些活动包括开发适合课堂的动手活动，并在圣路易斯地区教师暑期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.