A mutation in SPC42 , which encodes a component of the spindle pole body, results in production of two-spored asci in Sa
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O R I GI N A L P A P E R
S. Ishihara á A. Hirata á M. Minemura S. Nogami á Y. Ohya
A mutation in SPC42, which encodes a component of the spindle pole body, results in production of two-spored asci in Saccharomyces cerevisiae Received: 8 August 2000 / Accepted: 7 December 2000 / Published online: 5 April 2001 Ó Springer-Verlag 2001
Abstract In the yeast Saccharomyces cerevisiae, SPC42 is an essential gene, which encodes one of the major components of the spindle pole body (SPB). We report on a mutation in the SPC42 gene (spc42-102) that results in a sporulation-speci®c defect. Mitotic growth of haploid and diploid spc42-102 strains is normal and both exhibit the same growth rates as the isogenic wild-type strains. Many diploid spc42-102/spc42-102 cells undergo normal meiotic nuclear divisions, producing four haploid nuclei. However, a signi®cant fraction of meiotic spc42-102/spc42-102 cells contain two immature SPBs and aberrant nuclei that are not surrounded by a prospore membrane. Some 40% of the resultant asci contain only two spores, while wild-type diploid cells almost always produce four-spored asci. Segregation of auxotrophic markers that are tightly linked to the centromere reveals that two-spore asci formed from spc42-102/spc42-102 diploid cells exclusively contain nonsister haploid spores. Western analysis and measurements of the ¯uorescent signal from an Spc42pGFP (green ¯uorescent protein) fusion reveal that the mutant strain fails to accumulate Spc42p at meiosis. Thus, our results suggest that insuciency of Spc42p
Communicated by C. P. Hollenberg S. Ishihara á M. Minemura á S. Nogami á Y. Ohya (&) Department of Integrated Biosciences, Graduate School of Frontier Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan E-mail: [email protected] Tel.: +81-3-5841-4473 Fax: +81-3-5802-3366 A. Hirata Institute of Molecular and Cellular Biosciences, Biology, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan Y. Ohya Unit Process and Combined Circuit, PRESTO, Japan Science and Technology Corporation, Shinsenri-Higashimachi 1-4-2, Toyonaka-shi, Osaka 565-0082, Japan
during meiosis results in a pair of immature nonsister SPBs that are not enclosed by prospore membrane. Keywords Meiosis á Prospore membrane formation á SPC42 á Spindle pole body á Saccharomyces cerevisiae
Introduction Sporulation in the budding yeast Saccharomyces cerevisiae provides a model system for studying developmental processes found in many eukaryotic cells. Initiation of sporulation in this yeast is controlled by a combination of cell types and environmental signals. Sporulation in the a/a diploid cells is triggered by starvation for nitrogen and a fermentable carbon source. Upon induction, cells exit from the mitotic cell cycle and enter meiosis. The three main landmark events in sporulation are: (1) prophase, during which meiotic DNA synthesis, meiotic recombination and formation of synaptonemal complexes occur; (2) two successive nuclear divisions called meiosis I and meiosis II; and (3) prospore membrane
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