UC Berkeley

Pairing Centers mediate meiotic chromosome dynamics in C. elegans

All sexually reproducing animals depend on meiosis, the specialized cell division in which haploid gametes are produced from a diploid germ cell. Meiotic cells undergo one round of replication followed by two rounds of division. A distinctive feature of the first meiotic prophase is the establishment of physical linkages, via crossover recombination, between homologous chromosomes, which are essential for their proper segregation at metaphase I. Prior to the recombination step, however, homologous chromosomes must overcome the problem of finding and recognizing their appropriate partner within the nuclear volume, a process called homolog pairing. Transient interactions between paired homologs are further stabilized by a process called synapsis, in which the synaptonemal complex polymerizes along the entire length of paired chromosome axes. My research aims to address central questions to our understanding of the meiotic process: how do homologous chromosomes find and recognize their correct partner and how is synapsis regulated so that it occurs only between properly paired homologs. In Chapter 1, I present data that Pairing Centers are essential to facilitate proper connections between chromosomes and the nuclear envelope by recruiting a polo-like kinase. In Chapter 2, I identify novel meiotic mutants through a candidate screen and present my preliminary characterization of their meiotic defects. I further describe tools to visualize their chromosome dynamics in vivo.