Nag D K, Koonce M P, Axelrod J
Wadsworth Center, and Department of Biomedical Sciences, School of Public Health, State University of New York, Albany 12201, USA.
Mol Cell Biol. 1997 Dec;17(12):7029-39. doi: 10.1128/MCB.17.12.7029.
During meiosis, a diploid cell undergoes two rounds of nuclear division following one round of DNA replication to produce four haploid gametes. In yeast, haploid meiotic products are packaged into spores. To gain new insights into meiotic development and spore formation, we followed differential expression of genes in meiotic versus vegetatively growing cells in the yeast Saccharomyces cerevisiae. Our results indicate that there are at least five different classes of transcripts representing genes expressed at different stages of the sporulation program. Here we describe one of these differentially expressed genes, SSP1, which plays an essential role in meiosis and spore formation. SSP1 is expressed midway through meiosis, and homozygous ssp1 diploid cells fail to sporulate. In the ssp1 mutant, meiotic recombination is normal but viability declines rapidly. Both meiotic divisions occur at the normal time; however, the fraction of cells completing meiosis is significantly reduced, and nuclei become fragmented soon after meiosis II. The ssp1 defect does not appear to be related to a microtubule-cytoskeletal-dependent event and is independent of two rounds of chromosome segregation. The data suggest that Ssp1 is likely to function in a pathway that controls meiotic nuclear divisions and coordinates meiosis and spore formation.
在减数分裂过程中，一个二倍体细胞在一轮DNA复制后经历两轮核分裂，以产生四个单倍体配子。在酵母中，单倍体减数分裂产物被包装成孢子。为了深入了解减数分裂发育和孢子形成，我们追踪了酿酒酵母中减数分裂细胞与营养生长细胞中基因的差异表达。我们的结果表明，至少有五类不同的转录本代表在孢子形成程序不同阶段表达的基因。在这里，我们描述其中一个差异表达基因SSP1，它在减数分裂和孢子形成中起重要作用。SSP1在减数分裂中期表达，纯合的ssp1二倍体细胞不能形成孢子。在ssp1突变体中，减数分裂重组正常，但活力迅速下降。两次减数分裂都在正常时间发生；然而，完成减数分裂的细胞比例显著降低，并且在减数分裂II后不久细胞核就会碎片化。ssp1缺陷似乎与微管细胞骨架依赖性事件无关，并且独立于两轮染色体分离。数据表明，Ssp1可能在控制减数分裂核分裂以及协调减数分裂和孢子形成的途径中发挥作用。
