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Roy Welch from Syracuse University will be the speaker for the Friday Nov. 19 Science at the Edge seminar. Roy has been a pioneer in taking systems biology approaches to study Myxococcus xanthus swarming movement and fruiting body development. He wants to understand emergent properties of multicellular systems and is using a combination of bioinformatics (phylogenomics), expression profiling, and quantitative analysis of time-lapse microscopy of mutants. SCIENCE AT THE EDGE SEMINAR QB/GEDD Friday, November 19 at 11:30am Room 1400 Biomedical and Physical Sciences Bldg. Refreshments at 11:15 Roy Welch Department of Biology, Syracuse University The Genotype to Phenotype Problem: Reverse Engineering the Genetics of Pattern Formation in a Multicellular Prokaryote Under starvation conditions, a swarm of Myxococcus xanthus cells will undergo development, a multicellular process culminating in the formation of many cell aggregates called fruiting bodies, each containing up to 100,000 cells. Despite the success of molecular genetics in identifying genes and pathways involved in this process, the mechanics of symmetry-breaking and the self-organization of a swarm into fruiting bodies remains poorly understood. We are using microcinematography and automated image processing to quantify transient features of developmental dynamics. An analysis of experimental data indicates that aggregation reaches its steady state in highly non-monotonic fashion; the number of aggregates rapidly peaks at a value two-to-three fold higher than the final value and then decreases before reaching a steady state. The time-dependence of aggregate size is also non-monotonic, but to a smaller extent: average aggregate size increases from onset of aggregation to between 10-15 hours and then gradually decreases thereafter. During this process, the distribution of aggregates transitions from a random state early in development to a more ordered state later in development. A comparison of these experimental data with results from current mathematical models indicates that the models fail to reproduce many of the dynamical features of aggregation, even though they may accurately describe the final outcome. Helen Geiger Administrative Assistant Quantitative Biology Graduate Program/ Gene Expression in Development & Disease Michigan State University 502B Biochemistry Building East Lansing, MI 48824 Phone: (517) 432-9895 Fax: (517) 353-9334 E-mail: [log in to unmask]<mailto:[log in to unmask]> Web: http://qbmi.msu.edu<http://qbmi.msu.edu/> http://www.bch.msu.edu/GEDD/index.htm<http://www.bch.msu.edu/GEDD/MSU-TRSB-Symposium.htm>