Presenter(s): Nicole Szczepanski
Faculty Mentor(s): Diana Libuda & Austin Harvey
Poster 19
Session: Sciences
Accurate chromosome segregation is critical for the formation of viable gametes by the specialized cell division of meiosis. During meiosis, programmed double strand DNA breaks (DSBs) are formed and repaired by recombination mechanisms to maintain genomic integrity and to promote proper chromosome segregation. In order to better understand early repair dynamics of DSBs, we intended to devise a strain via CRISPR with an early repair phenotype closer to wildtype phenotype for future live imaging experiments. In past experiments, endogenously tagged GFP::RAD-51 mutants were utilized, but strayed from the usual wildtype phenotype. RAD-51 is a conserved recombinase that indicates an early repair stage of DSBs and is required for all meiotic recombination events. Using immunofluorescence, DSBs display distinct early repair dynamics through differential RAD-51 foci, leading to the hypothesis that these distinct dynamics indicate different DSB repair outcomes. Using the C. elegans model, we found that endogenously tagged GFP::RAD-51 mutants did not show a more wildtype RAD-51 foci phenotype after inheriting two copies of wildtype RAD-51 compared to worms that did not inherit the duplication. We also found that there is a significant difference between RAD-51 foci in early pachytene and late pachytene, the former having larger volumes and stronger intensities, representing interhomolog repair outcomes. In addition, interhomolog crossover repair outcomes show smaller, dimmer foci than do noncrossover outcomes. This indicates differential DSB end-resectioning between different stages within meiosis and between different repair outcomes.