Dorsal and intermediate neuronal cell types of the spinal cord are established by a BMP signaling pathway

摘要: We have studied the role of Bmp signaling in patterning neural tissue through use mutants zebrafish that disrupt three different components a pathway: swirl/bmp2b, snailhouse/bmp7 and somitabun/smad5. demonstrate is essential for establishment prospective crest dorsal sensory Rohon-Beard neurons spinal cord. Moreover, necessary to limit number intermediate-positioned lim1+ interneurons cord, as observed by dramatic expansion these many mutant embryos. Our analysis also suggests positive specification interneurons, which independent Bmp2b/Swirl activity. found presumptive ventral signal, Hh signaling, acts restrict amount trunk crest. This restriction appears occur very early development, likely prior notochord or floor plate formation. A similar suggested cell types, since bmp2b/swirl bmp7/snailhouse genes are only coexpressed during gastrulation within tail bud, not tube overlying epidermal ectoderm. Thus, gastrula Bmp7/Snailhouse-dependent activity gradient may act embryonic dorsoventral axis, but function establishing intermediate neuronal types