We are investigating the differentiation of the somatic and visceral muscle and the heart. In a systematic search for genes involved in these events, we undertook a molecular screen using subtractive hybridisation coupled to cDNA library construction. This produced a subtracted library enriched at least 100-fold for mesodermal cDNAs. We determined the expression patterns during embryogenesis of 600 of these clones and assessed whether those with significant patterns were novel genes by DNA sequencing. Whilst a number were previously known, most were novel.
Current work centres on four novel clones expressed during myogenesis.
Clone 1 is specifically expressed in the somatic muscle progenitors, and also more weakly in those of the visceral muscle and heart. During differentiation its expression resembles that of Dmef2 . Clone 2 is expressed specifically in the progenitors of the heart and somatic muscle, and at stage 11 its expression pattern resembles a superimposition of the expression patterns of twi and tin . Both clones 3 and 4 are expressed transiently in the differentiating somatic and visceral muscle between stages 11-14. The expression of both clones 1 and 2 is dependent on twi , but independent of Dmef2 .