Hereditas

Seeing is believing: the Bicoid protein reveals its path

The Bicoid (Bcd) protein gradient in Drosophila is a fascinating observation in nature and has served in textbooks as a paradigm for morphogen gradient formation for decades. Until recently, it was unclear how the Bcd protein moved towards the posterior end during the early nuclear cycle stages of the Drosophila egg to form the gradient. This commentary summarizes recent findings on the path, demonstrating that the protein does not move throughout the yolk, but rather moves along a discrete path along the cortex.  his observation is consistent with the ARTS model of gradient formation where the Bcd protein gradient is preceded by a bcd mRNA gradient.