PATTERN-FORMATION BY TRANSCRIPTIONAL CASCADES IN THE DROSOPHILA EMBRYO

Genetic and molecular analyses have combined to yield insights into functional cascades of transcription factors necessary to establish the molecular blueprint of the Drosophila body pattern in response to positional information already present in the egg. This maternal information is based on a small set of asymmetrically distributed maternal transcription factors that act as graded morphogens along the anterior-posterior and the dorsal-ventral axes of the embryo. Recent progress in the field provides first insight into the molecular mechanisms by which long-range positional information in the egg causes a series of localized zygotic transcription factor gradients to position development fate along the axes of the blastoderm embryo.