title: Segregation of recombined chromosomes in meiosis I requires DNA topoisomerase II.
abstract: To understand better the similarities and differences between meiosis and mitosis, we examined the meiotic role of DNA topoisomerase II, an enzyme that is required mitotically to disentangle sister chromatids at the time of chromosome segregation. In meiosis, we found that topoisomerase II is required only at the time of nuclear division. When cold-sensitive top2 mutants are induced to sporulate at the restrictive temperature, they undergo premeiotic DNA synthesis and commitment to meiotic levels of recombination but fail to complete the first meiotic nuclear division. The introduction of a mutation blocking recombination relieves the requirement for topoisomerase II in meiosis I. These results suggest that topoisomerase II is required at the time of chromosome segregation in meiosis I for the resolution of recombined chromosomes.
authors.affiliation: Department of Cellular and Developmental Biology, Harvard University, Cambridge, Massachusetts 02138.
authors.forename: D
authors.initials: D
authors.lastname: Rose
authors.forename: W
authors.initials: W
authors.lastname: Thomas
authors.forename: C
authors.initials: C
authors.lastname: Holm
mesh_terms: D002467:Cell Nucleus / Q000648:ultrastructure; D015825:Chromosomes, Fungal / Q000502:physiology* / Q000648:ultrastructure; D004261:DNA Replication; D004250:DNA Topoisomerases, Type II / Q000378:metabolism*; D008540:Meiosis; D009154:Mutation; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics*; D013172:Spores, Fungal / Q000502:physiology; D013696:Temperature
chemical_list: D004250:DNA Topoisomerases, Type II