Project description:Comparative genome hybridization (CGH) was used to measure relative DNA replication after 8 hours in meiosis for wild-type and cdc6-mn cells. We measured DNA replication after 8 hours in meiosis for wild-type and cdc6-mn cells on microarrays using CGH.
Project description:Comparative genome hybridization (CGH) was used to measure relative DNA replication after 8 hours in meiosis for wild-type and cdc6-mn cells.
Project description:Mcm2-7 ChIP in pre-meiotic and pre-mitotic cells, axis factor ChIP in wild-type and replication compromised strains in meiosis Multiple studies of meiotic chromosomes were undertaken. To study DNA replication, the locations of replicative helicase (Mcm2-7) were mapped in pre-meiotic and pre-mitotic cells, and DNA replication profiles were created for pre-meiotic S (meiS) and pre-mitotic S (mitS) phases. Early origins were mapped in hydroxyurea for wild-type cells in mitS + 200mM HU, and meiS +20mM HU for wild-type, sml1, rec8 and spo11 deletion cells. Rec8, Hop1 and Red1 binding to meiotic chromosomes was evaluated using ChIP-chip in wild-type cells with and without 20 mM HU, and in cdc6-mn and clb5 clb6 delete cells. Finally, meiotic DNA double-strand breaks (DSBs) were mapped in cdc6-mn dmc1 delete cells by measuring the ssDNA that accumulates at DSB hotspots.
Project description:During gamete formation, crossover recombination must occur on replicated DNA to ensure proper chromosome segregation in the first meiotic division. We identified a Mec1/ATR-dependent replication checkpoint in budding yeast that prevented the earliest stage of recombination, the programmed induction of DNA double-strand breaks (DSBs), when pre-meiotic DNA replication was delayed. The checkpoint suppressed DSBs through three complementary mechanisms: inhibition of Mer2 phosphorylation by Dbf4-dependent Cdc7 kinase, preclusion of chromosomal loading of Rec114 and Mre11, and lowered abundance of the Spo11 nuclease. Without this checkpoint, cells formed DSBs on partially replicated chromosomes. Importantly, such DSBs frequently failed to be repaired and impeded further DNA synthesis, leading to a rapid loss in cell viability. We conclude that a checkpoint-dependent constraint of DSB formation to duplicated DNA is critical not only for meiotic chromosome assortment, but also to protect genome integrity during gametogenesis. DSB factor association was measured in wild-type and checkpoint mutants strains under non-inducing or replication checkpoint inducing conditions. Additionally, DNA replication and helicase loading were measured in a replication and checkpoint deficient strain (cdc6-mn).
Project description:TrAEL-seq was performed on hydroxyurea-blocked and then released yeast cells to track replication fork stalling and replication fork restart, in wild-type and replisome mutant strains.
Project description:DSBs were mapped genome-wide by ssDNA enrichment in cdc6-mn replication comprimsied strains. We mapped DSB sites by detecting DSB-associated ssDNA enrichment on microarrays. To test the role of DNA replication in DSB formation, we mapped ssDNA in a cdc6-mn replication depleted strain. ssDNA was isolated from cells after 5 hours in sporulation medium. As a reference, ssDNA isolated from cells at 0 hrs in sporulation medium prior to DSB formation was differentially labeled and co-hybridized to the same array. For each experiment, we have submitted biological replicates that were hybridized to separate arrays. For each experiment a dye swap was performed and shown to have no effect on the data observed, although not all experiments in this series include the dye swap sample (we have included only two representative experiments for each strain).
