Invertebrate myogenesis: looking back to the future of muscle development

Recent studies in invertebrates have provided important mechanistic insight s into several general aspects of muscle development. Two new genes have be en identified that are involved in muscle fusion in Drosophila and a novel maternal component was shown to be responsible for myogenic determination i n an ascidian. In addition, genetic analyses of nematode and Drosophila hom ologues of factors known to be myogenic regulators in other species yielded surprising findings about both the evolutionary conservation and divergenc e of these functions. Drosophila myogenesis has become a highly informative model for understanding the interplay between the signaling and transcript ional networks that underlie cell-fate specification during embryonic devel opment.