In a previous issue of Cell Cycle,' Cornelia Rumpf and colleagues report their discovery of dill1 a novel gene in fission yeast required for chromosome segregation in meiosis. In meiosis, one round of DNA replication is followed by two successive rounds of chromosome segregation (meiosis I and meiosis II), generating haploid gametes from diploid precursor cells. Among a number of fundamental differences between mitosis and meiosis (reviewed in ref. 2), recombination in meiosis is used to provide a physical connection between homologous chromosomes, which ensures their correct segregation. During meiosis I, homologous chromosomes (each consisting of two sister chromatids) locate each other, pair and recombine during an extended prophase. Homologous chromosomes are then segregated to opposite poles while sister chromatids remain physically attached through meiosis-specific cohesion. Pairing of homologous chromosomes is important for homologous recombination, and both events contribute to the accurate segregation of chromosomes during meiosis.
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