Heteroduplex DNA and meiotic recombination in Drosophila Public Deposited

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  • March 20, 2019
  • Radford, Sarah J.
    • Affiliation: School of Medicine, Curriculum in Genetics and Molecular Biology
  • Meiotic recombination gives rise to crossovers, which are required in most organisms for the faithful segregation of homologous chromosomes during meiotic cell division. Investigation of the details of this process has centered largely on studies in fungi; however, recent evidence suggests that a complete understanding will require this question to be approached in multiple model organisms. In this thesis, I report the development of tools for expanding the study of meiotic recombination in Drosophila melanogaster. I have combined an existing assay for the selection of rare recombination events with molecular techniques to allow the fine dissection of the structures of recombination events. I demonstrate the utility of this assay by using it to investigate recombination in a known meiotic mutant, mei-9. The results of this investigation provide evidence supporting a role for MEI-9 in resolving recombination intermediates to generate crossovers, and supporting a model in which noncrossovers are generated by multiple pathways. I also report the genetic characterization of the role of a partner protein of MEI-9, ERCC1. These results suggest that the functional protein complex for the generation of meiotic crossovers contains MEI-9, ERCC1, and a previously-characterized protein, MUS312. Additionally, I created a Drosophila mismatch repair mutant, Msh6, and used my newly-developed assay to investigate meiotic recombination events in this mutant. This constitutes the first investigation of meiotic mismatch repair in Drosophila. Results of this assay show that elimination of mismatch repair allows the recovery of unrepaired heteroduplex DNA with high efficiency. Characterization of the structure and arrangement of heteroduplex DNA is instrumental in the dissection of molecular models of meiotic recombination. The creation of a mutant in which heteroduplex DNA can be recovered in Drosophila does much to put the molecular characterization of meiotic recombination in this organism on a par with studies in fungi. Using this assay, I also show strong evidence for a "short-patch" repair pathway that acts in the absence of canonical mismatch repair in Drosophila. In this thesis, I demonstrate the importance and effectiveness of using Drosophila to further our understanding of the crucial process of meiotic recombination, and report the development of a number of tools that demonstrate the attractiveness of using this model organism for these studies.
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  • Sekelsky, Jeff
  • Open access

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