Developmental expression of the POU transcription factor qBrn-2 during semitic myogenesis in quail

We prepared a specific antiserum to the qBrn-2 protein and examined the dev elopmental distribution of this protein during quail semitic myogenesis. In contrast to its mammalian homolog N-Oct-3, qBrn-2 exhibited an impressive spatio-temporal profile in semitic myogenesis, in addition to the orthodox expression observed in the developing neural tube. In somites, qBrn-2 was e xpressed in the outer epithelial cells, but not in the core cells. During t he somite differentiation, qBrn-2 expression was enhanced a nd restricted t o myotome. The location of qBrn-2 expression seemed to overlap with that of myf5 and myoD in myotome. However, in cells that just began to express myf 5 or myoD, qBrn-2 expression was not obvious. As embryonic development proc eeded, qBrn-2 positive cells in myotome migrated dorsally and ventrally, an d qBrn-2 expression was still observed at dorsal and ventral muscle masses in the forelimb. On the basis of our observations, it seems that qBrn-2 may play important roles in the determination, differentiation and migration o f muscle precursor cells, in addition to its known roles in neurogenesis.