Ambros V
Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
Novartis Found Symp. 2001;237:203-14; discussion 214-20. doi: 10.1002/0470846666.ch16.
The nematode Caenorhabditis elegans develops through two major phases: the first phase, embryogenesis, consists of a rapid series of cleavage cell divisions leading to morphogenesis of a first stage larva. The second phase is postembryonic development, which consists of developmentally regulated cell cycles that occur during the four larval stages leading to the adult. Precursor cells set aside during embryogenesis divide through stereotypical cell lineage patterns during the four larval stages to generate larval and adult structures. The precise timing of the postembryonic cell divisions is under strict control, in most cases with a developmentally regulated G1. In certain postembryonic cell lineages, various aspects of the cell division cycle, including cell cycle exit, or G1/S progression, are controlled by temporal regulatory genes of the heterochronic gene pathway. Heterochronic genes also control the timing of numerous other developmental events, indicating that this pathway functions to coordinate the schedule of cell division and cellular differentiation throughout the animal. Some choices of cell fate that occur in response to inductive or lateral signals are linked to cell cycle progression, suggesting that cell cycle phase can confer a critical period for developmental potential in certain cells.
第一阶段是胚胎发生，由一系列快速的卵裂细胞分裂组成，导致第一阶段幼虫的形态发生。第二阶段是胚胎后发育，它由在四个幼虫阶段发生的受发育调控的细胞周期组成，最终发育为成虫。胚胎发生过程中预留的前体细胞在四个幼虫阶段通过定型的细胞谱系模式进行分裂，以生成幼虫和成虫结构。胚胎后细胞分裂的精确时间受到严格控制，在大多数情况下，具有受发育调控的G1期。在某些胚胎后细胞谱系中，细胞分裂周期的各个方面，包括细胞周期退出或G1/S进展，都由异时性基因途径的时间调控基因控制。异时性基因还控制许多其他发育事件的时间，这表明该途径的功能是协调整个动物的细胞分裂和细胞分化时间表。一些因诱导或侧向信号而发生的细胞命运选择与细胞周期进程相关，这表明细胞周期阶段可以赋予某些细胞发育潜能的关键时期。
