Isolation and characterization of C.elegans meiotic mutants - regulation of chromosome association dynamics during meiosis

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The tight control of chromosome association and dissociation during cell division ensures the viability of daughter cells. In meiosis, chromosomes separate in two steps such that first homologs segregate in meiosis I and later sister chromatids disjoin in meiosis II. To avoid the sudden separation of sister chromatids already in meiosis I and subsequent collapse of cell division, cohesion proteins must not be completely removed from meiosis I chromosomes. Eukaryotic cells accomplish that by differentially protecting subsets of cohesion proteins on chromosomes from the activity of separase, an enzyme required to break chromosomal links. By selectively protecting cohesion proteins, meiotic cells can sustain sister chromatid association past homolog segregation. This protection of cohesion has been correlated with the presence of the centromere, the connecting point between sister chromatids and a center hub from where chromosomes attach to the spindle. However, a whole set of animal and plant species have cells whose chromosomes do not have a classic centromere. Nonetheless, protection of chromosome cohesion in these organisms still needs to occur. The main objective of the research program is to investigate how protection of cohesion is regulated in this alternative chromosome architecture. To address this problem, meiosis in the nematode C.elegans, whose chromosomes lack centromeres, will be used to identify new genes necessary for the proper segregation of meiotic chromosomes. By utilizing genetic and molecular tools, this research will provide us with a better picture on how the mechanisms regulating chromosome separation evolved and help understand the precise role of the centromere in this process. Aside from chromosome biology and evolution, results from this research will impact the study of cell cycle regulators and provide a platform for future research on organisms whose chromosomes lack a defined centromere.