SYMMETRICAL CELL-DIVISION IN PSEUDOHYPHAE OF THE YEAST SACCHAROMYCES-CEREVISIAE
SYMMETRICAL CELL-DIVISION IN PSEUDOHYPHAE OF THE YEAST SACCHAROMYCES-CEREVISIAE
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DOI：
10.1091/mbc.5.9.1003
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发表时间：
1994-09-01
影响因子：
3.3
通讯作者：
FINK, GR
中科院分区：
文献类型：
--
作者：
KRON, SJ;STYLES, CA;FINK, GR
酿酒酵母菌实验室菌株是二态的；作为对氮饥饿的反应，它们从酵母菌形式（YF）转变为丝状假菌丝形式（PH）。分裂细胞的延时视频显微镜显示YF和PH细胞在细胞周期和出芽极性上存在差异。YF细胞周期在G1/S过渡时由细胞大小检查点Start控制。YF细胞不对称分裂，从正常大小的母体中产生小的子代。因此，母亲和女儿是异步发芽的。母细胞立即发芽，但子细胞在G1期生长，直到达到临界细胞大小。相比之下，PH细胞对称分裂，限制有丝分裂，直到芽长到母体大小。因此，在下一个周期中，母亲和女儿同步发芽，在Start之前没有G1延迟。YF和PH细胞也表现出不同的芽位选择模式。YF细胞是两极的，在两极产生第二芽和随后的芽。PH细胞是单极的，只从与母体接合的另一端产生第二芽和随后的芽。我们提出，在PH细胞中，G2细胞大小检查点延迟有丝分裂，直到芽的大小达到母细胞的大小。我们得出结论，酵母和PH形式是不同的细胞类型，每个都有独特的细胞周期，出芽模式和细胞形状。
Laboratory strains of Saccharomyces cerevisiae are dimorphic; in response to nitrogen starvation they switch from a yeast form (YF) to a filamentous pseudohyphal (PH) form. Time-lapse video microscopy of dividing cells reveals that YF and PH cells differ in their cell cycles and budding polarity. The YF cell cycle is controlled at the G1/S transition by the cell-size checkpoint Start. YF cells divide asymmetrically, producing small daughters from full-sized mothers. As a result, mothers and daughters bud asynchronously. Mothers bud immediately but daughters grow in G1 until they achieve a critical cell size. By contrast, PH cells divide symmetrically, restricting mitosis until the bud grows to the size of the mother. Thus, mother and daughter bud synchronously in the next cycle, without a G1 delay before Start. YF and PH cells also exhibit distinct bud-site selection patterns. YF cells are bipolar, producing their second and subsequent buds at either pole. PH cells are unipolar, producing their second and subsequent buds only from the end opposite the junction with their mother. We propose that in PH cells a G2 cell-size checkpoint delays mitosis until bud size reaches that of the mother cell. We conclude that yeast and PH forms are distinct cell types each with a unique cell cycle, budding pattern, and cell shape.