Developmental Biology of Size

Abstract

The Spemann organizer secretes the anti-BMP protein Chd, and provides dorsal positional information by inactivating the ventralizing signals BMPs in a spatially graded manner. Several studies have shown that a morphogenetic field exhibits a strong tendency of self-regulation. For instance, when a blastula embryo is bisected across the D-V axis, the dorsal half develops into a well-proportioned half-size embryo, which retains a nearly normal DV ratio. These observations indicate that the BMP activity gradient is dynamically and flexibly regulated in response to changes of the embryonic size. Here we demonstrate that the auto-regulatory loop of Chd degradation plays a decisive role in scaling.