Pokorná I, Svoboda A
Department of Biology, Faculty of Medicine, Masaryk University, Czech Republic.
Folia Microbiol (Praha). 1995;40(6):583-7. doi: 10.1007/BF02818513.
The mating process between two protoplasts or between a protoplast and a cell in the yeast Saccharomyces cerevisiae was manifested by a specific morphological response of only the cell partner. The cells produced projections, up to 5 micrometers long, to meet their protoplast partners. The protoplasts responded, after a period of nonspecific hernia-like growth, by ceasing to grow and assuming oval or spherical shapes. They never formed mating projections, apparently due to the absence of complete cell walls. Similarly to the cells, nuclear division in protoplasts was arrested and the nucleus migrated towards the plasma membrane at the site of protoplast-cell contact. Cytoplasmic microtubules were directed to this site, indicating the position of the spindle pole body (SPB) on the nucleus adjacent to the plasma membrane. Actin patches accumulated also in this region. These cytological features of the protoplasts were reminiscent of the reorganization of the cytoskeleton and nucleus characteristic of mating cells. This implies that the ability of protoplasts to produce and receive mating signals was unaffected by protoplasting. Fusion, however, was not initiated due to the absence of the complete cell wall in one of the partners. Thus, the cell wall appeared to be necessary for the expression of polarized growth during mating and for cell fusion.
在酿酒酵母中，两个原生质体之间或原生质体与细胞之间的交配过程仅通过细胞伙伴的特定形态反应表现出来。细胞产生长达5微米的突起以与它们的原生质体伙伴相遇。原生质体在一段非特异性的疝样生长后做出反应，停止生长并呈现椭圆形或球形。它们从未形成交配突起，显然是由于缺乏完整的细胞壁。与细胞类似，原生质体中的核分裂被阻断，细胞核朝着原生质体与细胞接触部位的质膜迁移。细胞质微管也指向该部位，表明纺锤极体（SPB）在与质膜相邻的细胞核上的位置。肌动蛋白斑也在该区域积累。原生质体的这些细胞学特征让人联想到交配细胞中细胞骨架和细胞核的重组。这意味着原生质体产生和接收交配信号的能力不受原生质体化的影响。然而，由于其中一个伙伴缺乏完整的细胞壁，融合并未启动。因此，细胞壁似乎是交配过程中极化生长表达和细胞融合所必需的。
