Reed B H
Whitehead Institute for Biomedical Research, Cambridge, MA, USA.
Bioessays. 1995 Jun;17(6):553-6. doi: 10.1002/bies.950170613.
The three cycles of cell division immediately following the formation of the cellular blastoderm during Drosophila embryogenesis display an invariant pattern. Bursts of transcription of a gene called string are required and sufficient to trigger mitosis at this time during development. The activator of mitosis encoded by the string gene is a positive regulator of cdc2 kinase and a Drosophila homologue of the Saccharomyces pombe cdc25 tyrosine phosphatase. Evidence presented in a recent paper demonstrates that transcription of string, and hence the timing and pattern of mitosis in the postblastoderm embryo, is under complex developmental control. Several lines of evidence support this interpretation, including the analysis of string transcription in pattern formation mutants, cell cycle arrest mutants, and the preliminary characterization of an extensive cis-acting regulatory region.
在果蝇胚胎发育过程中，紧接细胞胚盘形成后的三个细胞分裂周期呈现出一种不变的模式。此时，一种名为“string”的基因转录爆发是触发有丝分裂所必需且充分的。由“string”基因编码的有丝分裂激活因子是cdc2激酶的正调控因子，也是粟酒裂殖酵母cdc25酪氨酸磷酸酶的果蝇同源物。最近一篇论文中给出的证据表明，“string”基因的转录，以及胚盘后胚胎中有丝分裂的时间和模式，都受到复杂的发育控制。几条证据支持这一解释，包括对模式形成突变体、细胞周期停滞突变体中“string”基因转录的分析，以及对一个广泛的顺式作用调控区域的初步表征。
