Saccharomyces cerevisiae
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ABSTRACT:
PROVIDER: PRJNA103295 | ENA |
REPOSITORIES: ENA
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Project description:DNA double-strand breaks (DSBs) initiate meiotic recombination. Past DSB-mapping studies have used rad50S or sae2? mutants, which are defective in break processing, to accumulate DSBs, and report large (= 50 kb) “DSB-hot” regions that are separated by “DSB-cold” domains of similar size. Substantial recombination occurs in some DSB-cold regions, suggesting that DSB patterns are not normal in rad50S or sae2? mutants. We therefore developed novel methods that detect DSBs using ssDNA enrichment and microarray hybridization, and that use background-based normalization to allow cross-comparison between array datasets, to map genome-wide the DSBs that accumulate in processing-capable, repair-defective dmc1î and dmc1î rad51î mutants. DSBs were observed at known hotspots, but also in most previously-identified “DSB-cold” regions, including near centromeres and telomeres. While about 40% of the genome is DSB-cold in rad50S mutants, analysis of meiotic ssDNA from dmc1? shows that most of these regions have significant DSB activity. Thus, DSBs are distributed much more uniformly than was previously believed. Southern-blot assays of DSBs in selected regions in dmc1?, rad50S and wild-type cells confirm these findings. Comparisons of DSB signals in dmc1, dmc1 rad51, and dmc1 spo11 mutant strains identify Dmc1 as the primary strand transfer activity genome-wide, and Spo11-induced lesions as initiating all meiotic recombination. Keywords: DSB mapping, ChIP-chip, single strand DNA , BND cellulose
2007-12-31 | GSE8981 | GEO
Project description:DNA double-strand breaks (DSBs) initiate meiotic recombination. Past DSB-mapping studies have used rad50S or sae2? mutants, which are defective in break processing, to accumulate DSBs, and report large (= 50 kb) “DSB-hot” regions that are separated by “DSB-cold” domains of similar size. Substantial recombination occurs in some DSB-cold regions, suggesting that DSB patterns are not normal in rad50S or sae2? mutants. We therefore developed novel methods that detect DSBs using ssDNA enrichment and microarray hybridization, and that use background-based normalization to allow cross-comparison between array datasets, to map genome-wide the DSBs that accumulate in processing-capable, repair-defective dmc1î and dmc1î rad51î mutants. DSBs were observed at known hotspots, but also in most previously-identified “DSB-cold” regions, including near centromeres and telomeres. While about 40% of the genome is DSB-cold in rad50S mutants, analysis of meiotic ssDNA from dmc1? shows that most of these regions have significant DSB activity. Thus, DSBs are distributed much more uniformly than was previously believed. Southern-blot assays of DSBs in selected regions in dmc1?, rad50S and wild-type cells confirm these findings. Comparisons of DSB signals in dmc1, dmc1 rad51, and dmc1 spo11 mutant strains identify Dmc1 as the primary strand transfer activity genome-wide, and Spo11-induced lesions as initiating all meiotic recombination. Keywords: DSB mapping, ChIP-chip, single strand DNA , BND cellulose We use two different strategies to map the genome-wide distribution of meiotic DSBs in the yeast Saccharomyces cerevisiae. The first is a chromatin immunoprecipitation (ChIP) based approach that targets the Spo11p protein, which remains covalently attached to DSB ends in the rad50S mutant background. The second approach involves BND cellulose enrichment of the single strand DNA (ssDNA) recombination intermediate formed by end-resection at DSB sites following Spo11p removal. We use dmc1 and dmc1 rad51 mutants that accumulates meiotic single strand DNA intermediates
2007-12-30 | E-GEOD-8981 | biostudies-arrayexpress
Project description:Every chromosome requires at least one crossover to be faithfully segregated during meiosis. At least two levels of regulation govern crossover distribution; where the initiating DNA double-strand breaks (DSBs) occur and whether those DSBs are repaired as crossovers. We mapped meiotic DSBs in budding yeast by identifying sites of DSB-associated single-stranded DNA (ssDNA) accumulation. These analyses revealed substantial DSB activity in regions close to centromeres, where crossover formation is largely absent. Our data suggest that centromeric suppression of recombination occurs at the level of break repair rather than DSB formation. Additionally, we found an enrichment of DSBs within a ~100-kb region near the ends of all chromosomes. Introduction of new telomeres was sufficient to induce large ectopic regions of increased DSB formation, revealing a remarkable long-range effect of telomeres on DSB formation. The concentration of DSBs close to chromosome ends increases the relative DSB density on small chromosomes, providing an interference-independent mechanism to ensure that all chromosomes receive at least one crossover per homolog pair. Together, our results indicate that selective DSB repair accounts for crossover suppression near centromeres, and suggest a simple telomere-guided mechanism to ensure sufficient DSB activity on all chromosomes. Keywords: ssDNA analysis, comparative genomic hybridization, ChIP-chip
2007-11-15 | GSE9503 | GEO
Project description:In most eukaryotes, meiotic crossovers are essential for error-free chromosome segregation but are specifically repressed near centromeres to prevent missegregation. Recognized for >85 years, the molecular mechanism of this repression has remained unknown. Meiotic chromosomes contain two distinct cohesin complexes: pericentric complex (for segregation) and chromosomal arm complex (for crossing-over). We show that the pericentric-specific complex also actively represses pericentric meiotic double-strand break (DSB) formation and, consequently, crossovers. The fission yeast pericentric regions contain heterochromatin, removal of which can result in derepression in double-strand break formation and recombination during meiosis. We uncover the mechanism by which fission yeast heterochromatin protein Swi6 (mammalian HP1-homolog) prevents recruitment of activators of meiotic DSB formation such as Rec10. Localizing these missing activators to wild-type pericentromeres bypasses repression and generates abundant crossovers but reduces gamete viability.The molecular mechanism elucidated here likely extends to other species including humans, where pericentric crossovers can result in disorders such as Down syndrome. These mechanistic insights provide new clues to understand the roles played by multiple cohesin complexes, especially in human infertility and birth defects.
2018-06-14 | GSE115726 | GEO
Project description:Meiotic double-strand break end resection mapping by S1Seq
| PRJNA337955 | ENA
Project description:We determined nucleosome positions throughout the genome in diploid S. cerevisiae undergoing early stages of synchronous meiosis. This study sought to assess if systematic reorganization of nucleosomes occurs during meiotic prophase at or near sites of DNA double strand break formation.
2011-03-07 | GSE26452 | GEO
Project description:Crossovers formed by recombination between homologous chromosomes are important for proper homolog segregation during meiosis and for generation of genetic diversity. Optimal molecular analysis of DNA intermediates of recombination requires synchronous cultures. We previously described a mutant, pat1-as2, of the fission yeast Schizosaccharomyces pombe that undergoes synchronous meiosis at 25°C when an ATP analog is added to the culture. Here, we compare recombination intermediates in pat1-as2 at 25°C with those in the widely used pat1-114 temperature-sensitive mutant at 34°C, a temperature higher than optimal. DNA double-strand breaks at most hotspots are similarly abundant in the two conditions but, remarkably, a few hotspots are distinctly deficient at 25°C. In both conditions Holliday junctions at DNA break hotspots form more frequently between sister chromatids than between homologs, but a novel species, perhaps arising from invasion by only one end of broken DNA, is more readily observed at 25°C. Our results confirm the validity of previous assays of recombination intermediates in S. pombe and provide new information on the mechanism of meiotic recombination. DNA double-strand break analysis by immunoprecipation of Rec12-FLAG covalently linked to DNA (without exogenous crosslinking agent used) following meiotic induction via pat1-114 or pat1-as2 alleles
2013-09-20 | E-GEOD-49961 | biostudies-arrayexpress
Project description:Meiotic double-strand break mapping in spo11 mutants by S1Seq
| PRJNA631754 | ENA
Project description:Genomic features shaping the landscape of meiotic double-strand break hotspots in maize
| PRJNA328981 | ENA
Project description:Histone H3K4 methylation is a feature of meiotic recombination hotspots shared by many organisms including plants and mammals. Meiotic recombination is initiated by programmed double strand break (DSB) formation that in budding yeast is directed in gene promoters by histone H3K4 di/trimethylation. This histone modification is indeed recognized by Spp1, a PHD-finger containing protein that belongs to the conserved histone H3K4 methyltransferase Set1 complex. During meiosis, Spp1 binds H3K4me and recruits a DSB protein, Mer2, to promote DSB formation close to gene promoters. How Set1C and Mer2 related functions of Spp1 are connected is not clear.
2018-01-30 | PXD007590 | Pride