Genetic Analysis of Myxococcus Xanthus Sensory Transduction

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Intellectual MeritIn natural settings microbes often live in surface-associated communities called biofilms. Some biofilms are harmful. Biofilm damage results in estimated annual costs in excess of $1 billion due in part to morbidity and mortality of human health and in part to damage and biofouling of surfaces. Understanding the channels of communication between cells in a biofilm could lead to the development of mechanisms that suppress biofilm formation. A model organism for examining biofilm formation is Myxococcus xanthus, which induces biofilm formation as part of a unique life cycle leading to fruiting body development. The fruiting body is an asexual reproductive structure that contains dormant spores and that is formed by directed movement of tens of thousands of cells. The Dif chemosensory pathway regulates biofilm formation and fruiting body development in M. xanthus in response to cues provided by the environment and other cells. Two such cues are nutrient limitation, a general stimulus for the initiation of development, and the presence of specific lipids, which control directed cell movement. The pathway contains a receptor for perceiving the signals, two component phosphorelay systems for controlling the behavioral output, and other as yet unidentified components. This project seeks to determine the mechanisms by which the pathway responds to cues to change the behavior of the cells. Genetic approaches will be used to identify gene products involved in assimilating the cues. Confocal laser scanning microscopy and microcinematography will be used to examine how the cues impact the behavior of the cells by comparing the behavior of wild type cells with mutants lacking a component of the Dif pathway. Additional assays will be used to determine whether the mutants are defective in signal production, gene expression, or directed movement. Together these experiments are expected to reveal how this organism makes a biofilm and uses the biofilm to direct the formation of a fruiting body and the production of spores.Broader Impacts:The project will serve as a venue for training undergraduate and graduate students in the rigors of critical thinking, and experimental design and execution. This opportunity will be available to groups currently underrepresented in science careers notably minority, disabled, and female students. A signer is available for the hearing impaired students. Students will also learn of ethical issues in science using the book ?Scientific Integrity? by Frank Macrina supplemented with reading materials and case studies from other sources. The goal is to train the next generation of scientists while achieving diversity and equal opportunity.