Project description:Meiotic chromosome pairing, recombination, and fertility depends on the conserved loop-axis architecture of meiotic chromosomes. This architecture is modulated by condensin, a structural maintenance of chromosome (SMC) complex that catalyzes chromatin loop formation. Here, we investigated how condensin is recruited to meiotic chromosomes in Saccharomyces cerevisiae. We show that double-strand break (DSB) formation, the initiating event of meiotic recombination, causes condensin redistribution from the nucleolus to DSB hotspots, pericentromeric regions and axis attachment sites. Hotspot association of condensin correlates weakly with break probability but does not depend on local DSB formation, whereas association with axis sites and pericentromeric regions depends on the Scc2-associated pool of cohesin, another SMC complex. Intriguingly, Scc2 distribution also changes in response to DSB formation. As condensin and Scc2-cohesin both catalyze chromatin loop extrusion, their redistribution upon DSB formation implies a profound change in chromatin loop dynamics that may help promote proper chromosome pairing and DNA repair.
Project description:Purpose: determine if gH2AX and H3.3 are enriched at unsynapsed regions of chromosomes involved in translocations in mouse germ line (meiotic prophase I) Methods: testes were isolated from 4-week or 6-week old heterozygous carriers of a single Robertsonian translocation RB(8;12) or 3 Robertsonian translocations RB(8;12), RB(1;3) and RB(9;14) and controls. ChIP assays were conducted as described in Smagulova 2011. Experiments done in triplicate. Results: We find enrichment of gH2AX in the proximal gene-rich regions of translocation-associated chromosomes and reduced enrichment of gH2AX and H3.3 at sex chromosomes