Nag D K, Axelrod J
Wadsworth Center, Department of Biomedical Sciences, School of Public Health, State University of New York, Albany 12201, USA.
Methods. 1998 Dec;16(4):423-33. doi: 10.1006/meth.1998.0697.
Meiosis, a specialized cell division process, occurs in all sexually reproducing organisms. During this process a diploid cell undergoes a single round of DNA replication followed by two rounds of nuclear division to produce four haploid gametes. In yeast, the meiotic products are packaged into four spores that are enclosed in a sac known as an ascus. To enhance our understanding of the meiotic developmental pathway and spore formation, we followed differential expression of genes in meiotic versus vegetatively growing cells in the yeast Saccharomyces cerevisiae. Such comparative analyses have identified five different classes of genes that are expressed at different stages of the sporulation program. We identified several meiosis-specific genes including some already known to be induced during meiosis. Here we describe one of these previously uncharacterized genes, SSP1, which plays an essential role in meiosis and spore formation. SSP1 is induced midway through meiosis, and the homozygous mutant-diploid cells fail to sporulate. In ssp1 cells, meiosis is delayed, nuclei fragment after meiosis II, and viability declines rapidly. The ssp1 defect is not related to a microtubule-cytoskeletal-dependent event and is independent of two rounds of meiotic divisions. Our results suggest that Ssp1 is likely to function in a pathway that controls meiotic nuclear divisions and coordinates meiosis and spore formation. Functional analysis of other uncharacterized genes is underway.
减数分裂是一种特殊的细胞分裂过程，发生在所有有性生殖的生物体中。在此过程中，二倍体细胞经历一轮DNA复制，随后进行两轮核分裂，以产生四个单倍体配子。在酵母中，减数分裂产物被包装成四个孢子，这些孢子被包裹在一个称为子囊的囊中。为了加深我们对减数分裂发育途径和孢子形成的理解，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。这种比较分析确定了在孢子形成程序的不同阶段表达的五类不同基因。我们鉴定了几个减数分裂特异性基因，包括一些已知在减数分裂期间被诱导的基因。在这里，我们描述了这些以前未被表征的基因之一，SSP1，它在减数分裂和孢子形成中起重要作用。SSP1在减数分裂中期被诱导，纯合突变二倍体细胞不能形成孢子。在ssp1细胞中，减数分裂延迟，减数分裂II后细胞核碎片化，活力迅速下降。ssp1缺陷与微管细胞骨架依赖性事件无关，且独立于两轮减数分裂。我们的结果表明，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。对其他未被表征基因的功能分析正在进行中。
