Zelda Binding in the Early Drosophila melanogaster Embryo Marks Regions Subsequently Activated at the Maternal-to-Zygotic Transition
(A) Fraction of regions highly bound (top 300 regions from ) by each of 21 transcription factors involved in anterior-posterior or dorsal-ventral patterning at cycle 14 that are bound by ZLD at cycle 8. As a control, narrow black bars show coverage after random reshuffling of ZLD-bound regions (B) For eight factors from , we compare the fraction of genome-wide recognition site occurrences that are occupied by each factor (blue), to the fraction of occupied sites that occur in regions that were bound by ZLD in cycle 8 (green). The significant increase in the probability of a factor binding to its own recognition sites in ZLD-bound regions emphasizes the role that ZLD plays in activation of the zygotic genome. Red bars mark the expected percent of TF-occupied sites among ZLD peaks, even in the absence of a TF-recognition element. We analyzed only the eight factors with clear simple recognition elements based on in vitro binding data.