Weinberg E S, Allende M L, Kelly C S, Abdelhamid A, Murakami T, Andermann P, Doerre O G, Grunwald D J, Riggleman B
Department of Biology, University of Pennsylvania, Philadelphia 19104, USA.
Development. 1996 Jan;122(1):271-80. doi: 10.1242/dev.122.1.271.
We describe the isolation of the zebrafish MyoD gene and its expression in wild-type embryos and in two mutants with altered somite development, no tail (ntl) and spadetail (spt). In the wild-type embryo, MyoD expression first occurs in an early phase, extending from mid-gastrula to just prior to somite formation, in which cells directly adjacent to the axial mesoderm express the gene. In subsequent phases, during the anterior-to-posterior wave of somite formation and maturation, expression occurs within particular regions of each somite. In spt embryos, which lack normal paraxial mesoderm due to incorrect cell migration, early MyoD expression is not observed and transcripts are instead first detected in small groups of trunk cells that will develop into aberrant myotomal-like structures. In ntl embryos, which lack notochords and tails, the early phase of MyoD expression is also absent. However, the later phase of expression within the developing somites appears to occur at the normal time in the ntl mutants, indicating that the presomitogenesis and somitogenesis phases of MyoD expression can be uncoupled. In addition, we demonstrate that the entire paraxial mesoderm of wild-type embryos has the potential to express MyoD when Sonic hedgehog is expressed ubiquitously in the embryo, and that this potential is lost in some of the cells of the paraxial mesoderm lineage in no tail and spadetail embryos. We also show that MyoD expression precedes myogenin expression and follows or is coincident with expression of snaill in some regions that express this gene.
我们描述了斑马鱼MyoD基因的分离及其在野生型胚胎以及两种体节发育改变的突变体（无尾突变体ntl和扇尾突变体spt）中的表达情况。在野生型胚胎中，MyoD的表达首先出现在早期阶段，从原肠胚中期一直延伸到即将形成体节之前，在此期间，直接与轴旁中胚层相邻的细胞表达该基因。在随后的阶段，在体节从前向后形成和成熟的过程中，每个体节的特定区域会出现表达。在spt胚胎中，由于细胞迁移不正确而缺乏正常的轴旁中胚层，未观察到早期MyoD表达，而是首先在一小群将发育成异常肌节样结构的躯干细胞中检测到转录本。在缺乏脊索和尾巴的ntl胚胎中，MyoD表达的早期阶段也不存在。然而，在ntl突变体中，发育中的体节内后期表达似乎在正常时间出现，这表明MyoD表达的前体节形成期和体节形成期可以解偶联。此外，我们证明，当音猬因子在胚胎中普遍表达时，野生型胚胎的整个轴旁中胚层都有表达MyoD的潜力，而在无尾和扇尾胚胎中，轴旁中胚层谱系的一些细胞失去了这种潜力。我们还表明，MyoD的表达先于生肌调节因子的表达，并且在一些表达该基因的区域中，MyoD的表达跟随或与蜗牛蛋白的表达同时发生。
