Fig. 7.

Minimal model for the genetic program of germ–soma differentiation in V. carteri. Three key gene types are involved in programming differentiation: glsA, lag, and regA. At the 32-cell stage, the glsA gene acts to promote the asymmetric divisions that produce large–small sister-cell pairs. The lag genes then act in the large cells to repress the development of somatic characteristics, while the regA gene acts in the small cells to repress reproductive development. Adapted from D. L. Kirk (Kirk 2001, 2005; Kirk and Kirk 2004)