Author

Jan Christian

Published on SDB CoRe: Mar 26 2012

Organisms: Model Organisms; Invertebrates
Early Embryogenesis: Blastula
Embryonic Patterning: Axis Formation
Signaling: Morphogens and Gradients
Organism: Drosophila
Stage of Development: Embryo

Object Description

Morphogens are substances that form concentration gradients and elicit distinct cellular responses in a dose-dependent manner. In the early Drosophila embryo, the transcription factor Bicoid forms a morphogen gradient across a syncytium consisting of a common cytoplasm supporting many nuclei. This syncytium forms following fertilization when nuclei divide in the absence of cell division. The nuclei initially remain positioned near the center of the embryo (a–b, d–e) but then migrate to the periphery (c,f). Bicoid RNA (green shading) is deposited at the anterior pole of the egg (a,d) and a nuclear Bicoid protein gradient (orange shading) forms either by translation of the localized RNA followed by protein diffusion away from the pole (a–c) or by diffusion of RNA away from the pole followed by local translation of the graded RNA (d-f). Bicoid provides one of the simplest examples of a morphogen in that it can establish a gradient by simple diffusion inside of a cell, and is thought to function directly to guide the generation of different cell types by inducing unique transcriptional responses in a dose-dependent manner. WIREs Dev Biol 2012. DOI: 10.1002/wdev.2

References

Christian, J.L. Morphogen gradients in development: from form to function. WIREs Dev Biol, 2012, 1:3-15.

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