Boettiger Alistair N, Levine Michael
Biophysics Program, University of California, Berkeley, CA 94720, USA.
Science. 2009 Jul 24;325(5939):471-3. doi: 10.1126/science.1173976.
Drosophila embryogenesis is characterized by rapid transitions in gene activity, whereby crudely distributed gradients of regulatory proteins give way to precise on/off patterns of gene expression. To explore the underlying mechanisms, a partially automated, quantitative in situ hybridization method was used to visualize expression profiles of 14 developmental control genes in hundreds of embryos. These studies revealed two distinct patterns of gene activation: synchronous and stochastic. Synchronous genes display essentially uniform expression of nascent transcripts in all cells of an embryonic tissue, whereas stochastic genes display erratic patterns of de novo activation. RNA polymerase II is "pre-loaded" (stalled) in the promoter regions of synchronous genes, but not stochastic genes. Transcriptional synchrony might ensure the orderly deployment of the complex gene regulatory networks that control embryogenesis.
果蝇胚胎发育的特点是基因活性迅速转变，即粗略分布的调控蛋白梯度让位于精确的基因表达开/关模式。为了探究其潜在机制，我们采用了一种部分自动化的定量原位杂交方法，以可视化数百个胚胎中14个发育控制基因的表达谱。这些研究揭示了两种不同的基因激活模式：同步激活和随机激活。同步基因在胚胎组织的所有细胞中显示出新生转录本基本一致的表达，而随机基因则显示出从头激活的不稳定模式。RNA聚合酶II在同步基因的启动子区域被“预加载”（停滞），但在随机基因中则没有。转录同步可能确保控制胚胎发育的复杂基因调控网络有序展开。
