My long-term goal is to understand how specific chromosome interactions maintain genomic integrity. Although double strand DNA breaks (DSBs) damage the genome and their improper repair can drive genomic instability, DSBs are intentionally formed and then repaired with specific chromosome templates to promote proper chromosome segregation during meiosis, the specialized cell division used by sexually reproducing organisms to produce haploid gametes. Meiotic errors in chromosome segregation contribute to miscarriages, stillbirths, and birth defects. Furthermore, inaccurate DSB repair contributes to the development and progression of cancer. While repair of DSBs with the appropriate chromosome template is necessary for genomic integrity, very little is known as to how germ cells achieve this in the presence of other potential templates (sister chromatids vs. homologs).
The C. elegans model system has genetic, genomic, and cytological features that are ideal for analyzing meiotic DSB repair events. As DSB repair partner preference is not well-studied due to few assays available to detect intersister repair events during the specific stages of meiotic prophase, I have developed several tools in C. elegans that I utilize to detect and study the temporal, mechanistic, and dynamic features of these events.
ASSAYS FOR INTERSISTER REPAIR EVENTS. As the study of recombination pathway and partner preferences has been limited by few assays to assess sister chromatid repair outcomes, I am currently engineering and validating a set of sister chromatid repair assays to understand the relative utilization of both interhomolog and intersister recombination pathways during meiotic prophase progression. This assay system allows me to directly test for the presence of a switch in DSB repair partner preferences. In addition, the system enables the assessment of chromosome position and the roles of several meiotic chromosome structures and recombination proteins in promoting specific DSB repair outcomes and partner preferences.
LIVE IMAGING OF EARLY DSB REPAIR STAGES IN GERM CELLS. The relationships between cytologically observed foci indicating early DSB repair stages and different classes of repair events (crossovers vs. noncrossovers; interhomolog vs. intersister) are not well understood. I am investigating these relationships with a system I have developed to visualize the live dynamics of early DSBR stages in live germ cells. This live imaging assay system for early DSBR stages will be used to assess the dynamics of early DSB repair stages during different phases of meiotic prophase and to establish the roles of specific chromosome structures in regulating DSB formation and repair. Overall, these studies will reveal relationships in early DSB repair dynamics with changes in partner preference.