Modulation of temporal dynamics of gene transcription by activator potency in the Drosophila embryo

Abstract

The Drosophila embryo at the mid-blastula transition (MBT) experiences a concurrent receding of a first wave of zygotic transcription and surge of a massive second wave. It is not well understood how genes in the first wave become turned off transcriptionally and how their precise timing may impact embryonic development. Here we perturb the timing of the shutdown of Bicoid (Bcd)-dependent hunchback (hb) transcription in the embryo through the use of a Bcd mutant that has a heightened activating potency. A delayed shutdown increases specifically Bcd-activated hb levels that alter spatial characteristics of the patterning outcome and cause developmental defects. Our study thus documents a specific participation of the maternal activator input strength in timing molecular events in precise accordance with the MBT morphological progression.