Synchronous and Stochastic Patterns of Gene Activation in the Drosophila Embryo

Stalled Development? Most developmental control genes that pattern the Drosophila embryo appear to have stalled RNA polymerase II (Pol II) bound to them prior to their activation. Classical studies on the Drosophila heat shock genes have shown that stalled Pol II renders these genes “poised” for rapid induction by stress. Boettiger and Levine (p. 471 ) now provide evidence for another potential function of stalled Pol II: Stalled genes exhibit synchronous patterns of gene activation in the early Drosophila embryo so that most or all cells in an embryonic tissue display nascent transcripts at the onset of expression. This synchrony might promote transcriptional precision during development.