Conservative duplication of spindle poles during meiosis in Saccharomyces cerevisiae

During sporulation in diploid Saccharomyces cerevisiae, spindle pole bodies acquire the so called meiotic plaque, a prerequisite for spore formation. Mpc70p is a component of the meiotic plaque and is thus essential for spore formation. We show here that MPC70/mpc70 heterozygous strains most often p roduce two spores instead of four and that these spores are always nonsiste rs. In wild-type strains, Mpc70p localizes to all four spindle pole bodies, whereas in MPC70/mpc70 strains Mpc70p localizes to only two of the four sp indle pole bodies, and these are always nonsisters. Our data can be explain ed by conservative spindle pole body distribution in which the two newly sy nthesized meiosis II spindle pole bodies of MPC70/mpc70 strains lack Mpc70p .