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We have developed a gene-fusion system based on the Escherichia coli beta-glucuronidase gene (uidA). The uidA gene has been cloned from E. coli K-12 and its entire nucleotide sequence has been determined. beta-Glucuronidase has been purified to homogeneity and characterized. The enzyme has a subunit molecular weight of 68,200, is very stable, and is easily(More)
A site-specific recombination system that probes the relative probabilities that pairs of chromosomal loci collide with one another in living cells of budding yeast was used to explore the relative contributions of pairing, recombination, synaptonemal complex formation, and telomere clustering to the close juxtaposition of homologous chromosome pairs during(More)
Diploid yeast undergo meiosis under certain conditions of nutrient limitation, which trigger a transcriptional cascade involving two key regulatory genes. IME1 is a positive activator of IME2, which activates downstream genes. We report that Gcn5, a histone H3 acetylase, plays a central role in initiation of meiosis via effects on IME2 expression. An(More)
Meiotic recombination is initiated by Spo11-generated DNA double-strand breaks (DSBs) . A fraction of total DSBs is processed into crossovers (CRs) between homologous chromosomes, which promote their accurate segregation at meiosis I (MI) . The coordination of recombination-associated events and MI progression is governed by the "pachytene checkpoint",(More)
Proper segregation of chromosomes during meiosis requires the formation and repair of double-strand breaks (DSBs) to form crossovers. Repair is biased toward using the homolog as a substrate rather than the sister chromatid. Pch2 is a conserved member of the AAA(+)-ATPase family of proteins and is implicated in a wide range of meiosis-specific processes(More)
Errors segregating homologous chromosomes during meiosis result in aneuploid gametes and are the largest contributing factor to birth defects and spontaneous abortions in humans. Saccharomyces cerevisiae has long served as a model organism for studying the gene network supporting normal chromosome segregation. Measuring homolog nondisjunction frequencies is(More)
FISH analysis of well-spread chromosomes reveals that homologs are paired in vegetatively growing budding yeast diploid cells, via multiple interstitial interactions, and independent of recA homologs and mating type heterozygosity. Pairing is present during G1 and G2, and in cells arrested at G1 by mating pheromone, but is disrupted during S phase. Thus,(More)
PRP16 encodes an RNA-dependent ATPase required for the second step of mRNA splicing in S. cerevisiae. We have isolated seven alleles of PRP16 that, like the original allele prp16-1, allow splicing of introns with a mutant branch site (UACUAAC to UACUACC), by forming lariat intermediates at the mutant C nucleotide. Every suppressor mutation maps to the(More)
The relative probabilities that different pairs of chromosomal loci will collide with one another in vegetatively growing diploid yeast cells have been assessed using a genetic assay for Cre/loxP site-specific recombination. Recombination rates have been determined for 18 different pairs of loxP sites representing diverse pairs of positions within the(More)
Dynamic telomere repositioning is a prominent feature of meiosis. Deletion of a telomere-associated protein, Ndj1, results in the failure of both attachment and clustering of telomeres at the nuclear envelope and delays several landmarks of meiosis I, such as pairing, synaptonemal complex formation, and timing of the meiosis I division. We explored the role(More)