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

在斑马鱼中，wnt 3a和wnt 8在胚盘边缘的重叠区域中表达，随后在尾芽中表达。Wnt 3a和Wnt 8反义寡核苷酸的联合抑制导致神经外胚层的前化，背侧组织者的扩张和尾部结构的丢失。腹侧表达的同源异型盒基因vox、vent和ved介导Wnt 3a/8信号传导以限制背侧组织者结构域。尾部相关cdx 1a和cdx 4的表达在wnt 3a/8变形胚胎中强烈降低。与wnt 3a/8变形胚胎一样，cdx 1a/4变形胚胎显示尾部结构完全丧失，表明Cdx 1a和Cdx 4介导Wnt依赖的尾部形成。我们还发现cdx 1a/4的表达依赖于Fgf信号传导。HOXA 9A在WNT 3A/8和CDX 1A/4变形体胚胎中表达下调。Cdx介导的hoxa 9a表达需要FGF信号传导。这些数据表明，cdx基因介导Wnt信号传导，而cdx基因介导的Wnt信号传导与cdx基因的表达有关。 ...更多信息 在尾巴的形态发生中起着重要的作用。我们分离了一个斑马鱼突变体（cdh 1 ^<rk3>），其在e-钙粘蛋白/cdh 1基因中具有突变。受影响最严重的胚胎表现出外延延迟，减少收敛延伸运动，并从胚胎细胞的解离。受影响较轻的胚胎表现为前部神经组织变平，孵化腺的位置和形态异常，三叉神经节散在。母合子cdh 1 ^<rk3>胚在原肠胚形成过程中表现为外生停滞，其中被膜层（EVL）和卵黄合胞体层完成外生，而深层细胞（DC）未完成外生。用抗β-连环蛋白抗体的免疫组织化学和电子显微镜显示，DC和EVL之间的粘附大部分被破坏，但在MZcdh 1 ^突变体中，DC之间的粘附相对不受影响<rk3>。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epiboly运动中发挥作用。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