title: Identification of joint molecules that form frequently between homologs but rarely between sister chromatids during yeast meiosis.
abstract: We have investigated DNA interactions between homologs and between sister chromatids during meiosis in S. cerevisiae. We have detected a DNA species containing information from both parental chromosomes at a specific hotspot for meiotic recombination and double strand breaks (DSBs). These joint molecules are a prominent feature of meiotic prophase. They appear to be a major intermediate stage in DSB-promoted recombination, because they occur with appropriate timing and require known recombination functions. Other possibilities cannot be completely dismissed, however. Most or all joint molecules contain two full-length nonrecombinant strands from each parental duplex and thus do not consist of single Holliday junctions. Joint molecules form between sister chromatids at approximately 10% the interhomolog level. Also, joint molecule formation is aberrant in a mutant defective in the HOP1 gene, which encodes a meiotic chromosome structure component. General models for discrimination between homologs and sisters during meiosis are discussed.
authors.affiliation: Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, Massachusetts 02138.
authors.forename: A
authors.initials: A
authors.lastname: Schwacha
authors.forename: N
authors.initials: N
authors.lastname: Kleckner
mesh_terms: D015139:Blotting, Southern; D002842:Chromatids / Q000502:physiology*; D004271:DNA, Fungal / Q000302:isolation & purification / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D005800:Genes, Fungal; D006579:Heterozygote; D006720:Homozygote; D008540:Meiosis; D009692:Nucleic Acid Heteroduplexes / Q000302:isolation & purification / Q000378:metabolism*; D011995:Recombination, Genetic; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D012854:Sister Chromatid Exchange
chemical_list: D004271:DNA, Fungal; D009692:Nucleic Acid Heteroduplexes