Simchen Giora
Department of Genetics, The Hebrew University of Jerusalem, Jerusalem, Israel.
Bioessays. 2009 Feb;31(2):169-77. doi: 10.1002/bies.200800124.
In budding yeast, commitment to meiosis is attained when meiotic cells cannot return to the mitotic cell cycle even if the triggering cue (nutrients deprivation) is withdrawn. Commitment is arrived at gradually, and different aspects of meiosis may be committed at different times. Cells become fully committed to meiosis at the end of Prophase I, long after DNA replication and just before the first meiotic division (M(I)). Whole-genome gene expression analysis has shown that committed cells have a distinct and rapid response to nutrients, and are not simply insulated from environmental signals. Thus becoming committed to meiosis is an active process. The cellular event most likely to be associated with commitment to meiosis is the separation of the duplicated spindle-pole bodies (SPBs) and the formation of the spindle. Commitment to the mitotic cell cycle is also associated with the separation of SPBs, although it occurs in G1, before DNA replication.
在出芽酵母中，当减数分裂细胞即使在触发信号（营养物质剥夺）撤除后也无法回到有丝分裂细胞周期时，就达到了对减数分裂的决定性状态。决定性状态是逐渐达成的，减数分裂的不同方面可能在不同时间被决定。细胞在减数第一次分裂前期结束时完全进入减数分裂状态，这发生在DNA复制很久之后且就在第一次减数分裂（M(I)）之前。全基因组基因表达分析表明，进入决定性状态的细胞对营养物质有独特而快速的反应，并非简单地与环境信号隔绝。因此，进入减数分裂是一个活跃的过程。最有可能与进入减数分裂决定性状态相关的细胞事件是复制后的纺锤体极体（SPB）分离和纺锤体形成。进入有丝分裂细胞周期的决定性状态也与SPB分离有关，尽管它发生在G1期，即在DNA复制之前。
