Synaptonemal Complexes and Meiotic Chromosome Metabolism in Yeast

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The proposed experimentation addresses the structure and function of the synaptonemal complexes that form during meiosis in yeast. The proteins present in the complex will be isolated and characterized. Antibody directed against the proteins will be raised and then used to investigate the structure of the complexes using standard immunocytological techniques. The genes encoding the proteins will also be isolated. In related experiments, Dr. Kleckner will isolate and characterize both the rad50 gene and its product, and then determine the intracellular location of the product. Regulation of the rad50 gene, especially during meiosis will also be examined. Meiotic cell division, or meiosis, is an event common to the life cycles of virtually all eukaryotic organisms. During meiosis, homologous chromosomes pair and recombine, then segregate to the daughter nuclei. As yet, remarkably little is understood about the biochemical mechanism of eukaryotic recombination or its regulation. Paired chromosomes with sites of contact, or synapses have been observed in the microscope. The occurrence of such synaptonemal complexes appears to correlate with recombination. Some yeast mutants, in particular those affected in the rad50 gene, display lowered frequencies of recombination. The proposed isolation and characterization of the rad50 gene, its product and the protein components of the synaptonemal complex will lay a solid foundation for understanding the molecular events of eukaryotic recombination.