Cohesin and recombination proteins influence the G1-to-S transition in azygotic meiosis in Schizosaccharomyces pombe.

To determine whether recombination and/or sister-chromatid cohesion affect the timing of meiotic prophase events, the horsetail stage and S phase were analyzed in Schizosaccharomyces pombe strains carrying mutations in the cohesin genes rec8 or rec11, the linear element gene rec10, the pairing gene meu13, the double-strand-break formation genes rec6, rec7, rec12, rec14, rec15, and mde2, and the recombination gene dmc1. The double-mutant strains rec8 rec11 and rec8 rec12 were also assayed. Most of the single and both double mutants showed advancement of bulk DNA synthesis, start of nuclear movement (horsetail stage), and meiotic divisions by up to 2 hr.

Characterization of rec15, an early meiotic recombination gene in Schizosaccharomyces pombe.

In S. pombe strains mutant for rec15 aberrant ascus morphology, reduced spore viability and severe reduction of meiotic recombination was detected. Genetic and cytological analysis identified frequent interruption of meiosis after the first division, and nondisjunction I, as the main segregation errors in the mutant.

Linear element formation and their role in meiotic sister chromatid cohesion and chromosome pairing.

Fission yeast does not form synaptonemal complexes in meiotic prophase. Instead, linear elements appear that resemble the axial cores of other eukaryotes. They have been proposed to be minimal structures necessary for proper meiotic chromosome functions.