Honigberg S M, Esposito R E
Department of Molecular Genetics and Cell Biology, University of Chicago, IL 60637.
Proc Natl Acad Sci U S A. 1994 Jul 5;91(14):6559-63. doi: 10.1073/pnas.91.14.6559.
When yeast from the early stages of meiosis are transferred from sporulation to growth medium, they can reenter the mitotic cell cycle directly. In contrast, cells from later stages of meiosis (after the initiation of the first nuclear division) will complete meiosis and sporulation despite the shift to growth medium, a phenomenon known as "commitment to meiosis." This study reports the surprising finding that when the normal progression of meiosis is arrested, cells from later stages of meiosis can return to growth. Cells were arrested after the first or second meiotic division by three independent means: the spo14 mutation, the spo3-1 mutation, and a high-temperature arrest of wild-type cells. In every case, the arrested cells were able to form buds after transfer to growth medium. These cells, however, experienced a delay upon return to growth relative to uncommitted cells. We propose that the commitment phenomenon results from a transient delay of mitotic growth, which occurs specifically during meiosis, and that commitment does not involve an irreversible inhibition of mitosis as previously thought.
当处于减数分裂早期的酵母从孢子形成培养基转移至生长培养基时，它们能够直接重新进入有丝分裂细胞周期。相比之下，来自减数分裂后期（第一次核分裂开始后）的细胞，即便转移至生长培养基，仍会完成减数分裂和孢子形成，这一现象被称为“减数分裂承诺”。本研究报告了一个惊人的发现：当减数分裂的正常进程被阻断时，来自减数分裂后期的细胞能够恢复生长。通过三种独立的方法在第一次或第二次减数分裂后使细胞停滞：spo14突变、spo3 - 1突变以及野生型细胞的高温停滞。在每种情况下，停滞的细胞在转移至生长培养基后都能够形成芽。然而，相对于未承诺的细胞，这些细胞在恢复生长时经历了延迟。我们提出，承诺现象是由有丝分裂生长的短暂延迟导致的，这种延迟特别发生在减数分裂期间，并且承诺并不涉及如先前认为的对有丝分裂的不可逆抑制。
