THE COMMUNITY EFFECT IN XENOPUS MYOGENESIS IS PROMOTED BY DORSALIZINGFACTORS

The community effect describes a process required for Xenopus muscle p rogenitor cells to progress to the expression of myogenic genes. Past work has suggested that this effect is dependent on secreted factors r eleased by dorsolateral or dorsal lip cells. We show here that known d orsalizing molecules as well as other natural dorsal lip factors contr ibute to, but do not wholly account for, the community effect. We conc lude that, in addition to dorsalizing molecules, the community effect requires factors or conditions peculiar to the dorsolateral mesoderm, a region of the embryo that contains muscle progenitor cells.