The molecular analysis of the dorsal organizer formation in zebrafish early development.

在斑马鱼中，wnt3a和wnt8在胚皮边缘和尾芽的重叠区域表达。反义morpholino寡核苷酸对Wnt3a和Wnt8的联合抑制导致神经外胚层的前化、背侧组织的扩张和尾部结构的丧失。腹侧表达的同源盒基因vox、vent和ved介导Wnt3a/8信号传导以限制背侧组织者结构域。尾端相关的cdx1a和cdx4在wnt3a/8型胚中的表达明显降低。与wnt3a/8型胚一样，cdx1a/4型胚的尾部结构完全缺失，提示cdx1a和Cdx4介导了wnt依赖性的尾部形成。我们还发现cdx1a/4的表达依赖于Fgf信号。Hoxa9a在wnt3a/8和cdx1a/4胚中表达下调。cdx介导的hoxa9a表达需要Fgf信号。这些数据表明，cdx基因介导Wnt信号和p…More在尾巴的形态发生中起重要作用。我们分离出一种斑马鱼突变体（cdh1^<rk3>），该突变体在e-cadherin/cdh1基因中发生突变。受影响最严重的胚胎表现为表观发育迟缓，收敛伸展运动减少，细胞与胚胎分离。轻危胚胎前神经组织扁平，孵化腺定位及形态异常，三叉神经节散在。母胚-合子胚在原肠胚形成过程中表现为表观代谢阻滞，包膜层（EVL）和卵黄合胞层完成了表观代谢，而深层细胞（DC）未完成。使用抗β -catenin抗体的免疫组织化学和电镜观察显示，在MZcdh1^<rk3>突变体中，dc与EVL之间的粘附大部分被破坏，但dc之间的粘附相对不受影响。这些数据表明，e -钙粘蛋白介导的DC和EVL之间的细胞粘附在斑马鱼的表观代谢运动中起作用。少

In zebrafish, wnt3a and wnt8 are expressed in overlapping domains in the blastoderm margin and later in the tailbud. The combined inhibition of Wnt3a and Wnt8 by antisense morpholino oligonucleotides led to anteriorization of the neuroectoderm, expansion of the dorsal organizer, and loss of the tail structure. The ventrally expressed homeobox genes vox, vent, and ved mediated Wnt3a/8 signaling to restrict the dorsal organizer domain. The expression of the caudal-related cdx1a and cdx4 was strongly reduced in the wnt3a/8 morphant embryos. Like the wnt3a/8 morphant embryos, cdx1a/4 morphant embryos displayed complete loss of the tail structure, suggesting that Cdx1a and Cdx4 mediate Wnt-dependent tail formation. We also found that cdx1a/4 expression is dependent on Fgf signaling. hoxa9a expression was down-regulated in the wnt3a/8 and cdx1a/4 morphant embryos. Fgf signaling was required for Cdx-mediated hoxa9a expression. These data indicate that the cdx genes mediate Wnt signaling and p … More lay essential roles in the morphogenesis of the tail. We isolated a zebra fish mutant (cdh1^<rk3>) that has a mutation in the e-cadherin/cdh1 gene. The most severely affected embryos displayed epiboly delay, decreased convergent extension movements, and the dissociation of cells from the embryos. The less severely affected embryos showed flattened anterior neural tissue, abnormal positioning and morphology of the hatching gland, scattered trigeminal ganglia. Maternal-zygotic cdh1^<rk3> embryos displayed epiboly arrest during gastrulation, in which the enveloping layer(EVL) and the yolk syncytial layer but not the deep cells(DC) completed epiboly. Immunohistochemistry with an anti-beta-catenin antibody and electron microscopy revealed that adhesion between the DCs and the EVL was mostly disrupted but that the adhesion between DCs was relatively unaffected in the MZcdh1^<rk3> mutant. These data suggest that E-cadherin-mediated cell adhesion between the DC and EVL plays a role in the epiboly movement in zebrafish. Less