Coup-TF, a member of the nuclear receptor super-family, is present in the pool of maternal mRNAs and proteins in the sea urchin egg. The presence of this protein seems to be essential for the execution of the early developmental program, leading to all three embryonic layers. Our results demonstrate that Pl-Coup-TF morphants, i.e. Pl-Coup-TF morpholino knockdown embryos, resemble blastulae that lack archenteron at 24 hpf (hours post fertilization), a stage at which normal embryos reach the end of gastrulation in Paracentrotus lividus. At 48 hpf, when normal embryos reach the pluteus larva stage, the morphants are seemingly underdeveloped and lack the characteristic skeletal rods. Nevertheless, the morphant embryos express vegetal endomesodermal marker genes, such as Pl-Blimp1, Pl-Endo16, Pl-Alx1 and Pl-Tbr as judged by in situ hybridization experiments. The anterior neuroectoderm genes, Pl-FoxQ2, Pl-Six3 and Pl-Pax6, are also expressed in the morphant embryos, but Pl-Hbn and Pl-Fez mRNAs, which encode proteins significant for the differentiation of serotonergic neurons, are not detected. Consequently, Pl-Coup-TF morphants at 48 hpf lack serotonergic neurons, whereas normal 48 hpf plutei exhibit the formation of two bilateral pairs of such neurons in the apical organ. Furthermore, genes indicative of the ciliary band formation, Pl-Hnf6, Pl-Dri, Pl-FoxG and Pl-Otx, are not expressed in Pl-Coup-TF morphants, suggesting the disruption of this neurogenic territory as well. In addition, the Pl-SynB gene, a marker of differentiated neurons, is silent leading to the hypothesis that Pl-Coup-TF morphants might lack all types of neurons. On the contrary, the genes expressing signaling molecules, which establish the ventral/dorsal axis, Pl-Nodal and Pl-Lefty show the characteristic ventral lateral expression pattern, Pl-Bmp2/4, which activates the dorsal ectoderm GRN is down-regulated and Pl-Chordin is aberrantly over-expressed in the entire ectoderm. The identity of ectodermal cells in Pl-Coup-TF morphant embryos, was probed for expression of the ventral marker Pl-Gsc which was over-expressed and dorsal markers, Pl-IrxA and Pl-Hox7, which were silent. Therefore, we propose that maternal Pl-Coup-TF is essential for correct dissemination of the early embryonic signaling along both animal/vegetal and ventral/dorsal axes. Limiting Pl-Coup-TF's quantity, results in an embryo without digestive and nervous systems, skeleton and ciliary band that cannot survive past the initial 48 h of development.

Coup-TF 是核受体超家族的成员，存在于海胆卵中的母体 mRNA 和蛋白质库中。这种蛋白质的存在似乎对于早期发育程序的执行至关重要，导致所有三个胚胎层。我们的结果表明 Pl-Coup-TF morphant，即 Pl-Coup-TF 吗啉基因敲低胚胎，类似于在 24 hpf（受精后小时）缺乏原肠胚的囊胚，在这个阶段，正常胚胎在Paracentrotus lividus中达到原肠胚形成结束。在 48 hpf，当正常胚胎到达 pluteus 幼虫阶段时，morphant 似乎发育不全，缺乏特征性的骨骼杆。然而，morphant 胚胎表达植物性内胚层标记基因，例如通过原位杂交实验判断的Pl-Blimp1、Pl-Endo16、Pl-Alx1 和 Pl-Tbr。前部神经外胚层基因Pl-FoxQ2、Pl-Six3 和 Pl - Pax6也在变形胚胎中表达，但未检测到编码对血清素能神经元分化具有重要意义的蛋白质的 Pl-Hbn 和 Pl-Fez mRNA。因此，48 hpf 的 Pl-Coup-TF morphant 缺乏血清素能神经元，而正常的 48 hpf plutei 表现出在顶端器官中形成了两对这样的神经元。此外，指示纤毛带形成的基因Pl-Hnf6、Pl-Dri、Pl-FoxG和Pl-Otx，在 Pl-Coup-TF morphant 中不表达，表明该神经源性区域也受到破坏。此外，Pl-SynB基因（分化神经元的标记）是沉默的，导致假设 Pl-Coup-TF morphant 可能缺乏所有类型的神经元。相反，表达信号分子的基因，其建立腹侧/背侧轴，Pl-Nodal和Pl - Lefty显示出特征性的腹侧表达模式，Pl-Bmp2/4，激活背侧外胚层 GRN 被下调和Pl-Chordin在整个外胚层中异常过度表达。探查了 Pl-Coup-TF morphant 胚胎中外胚层细胞的身份，以确定过度表达的腹侧标记Pl-Gsc和沉默的背侧标记Pl-IrxA和Pl-Hox7 的表达。因此，我们建议母体 Pl-Coup-TF 对于沿动物/植物轴和腹侧/背轴正确传播早期胚胎信号传导至关重要。限制 Pl-Coup-TF 的数量会导致胚胎没有消化系统和神经系统，骨骼和睫状带无法在最初的 48 小时发育后存活。