Concentration gradients of activator and inhibitors of cellular differentiation in a filamentous cyanobacterium

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The cyanobacterium Anabaena differentiates specialized cells called heterocysts that supply a form of nitrogen that can be used for growth to the remainder of the cells of the organism. Heterocysts occur at approximately every tenth cell position on unbranched filaments that can be hundreds of cells in length. In this project, a molecular genetic approach will be used to investigate the interactions of an activator of differentiation with two inhibitors of differentiation. Degradation of the activator in response to varying concentrations of the inhibitors will be measured, the protease(s) involved in degradation of the activator will be identified, the molecular activity of one of the two inhibitors will be determined, and concentration gradients of the activator that governs formation of the pattern of heterocysts along filaments will be visualized. The activator ? inhibitor model has been proposed to describe the formation of many patterns seen in a wide variety of organisms. The simplicity of the Anabaena developmental system makes it ideal for testing many aspects of the model. In particular, this project will demonstrate for the first time inhibitor-dependent degradation of the activator of differentiation. This project is narrowly focused on the genetics of heterocyst differentiation in cyanobacteria, but the broader biological impact will be on the types of molecular mechanisms that control specification of cells for differentiation in many organisms. In addition to the research findings, this project will also promote teaching, training and learning by funding the research training of graduate students and undergraduate students, by enhancing sections of an undergraduate genetics laboratory course, by providing funded graduate students with teaching opportunities and by allowing their participation at national meetings. Mentoring of undergraduate students for research credit will potentially broaden the participation of students of Pacific Islander descent in the biological sciences.