Posterior elongation of the developing embryo is a common feature of animal development. One group of genes that is involved in posterior elongation is represented by the Wnt genes, secreted glycoprotein ligands that signal to specific receptors on neighbouring cells and thereby establish cell-to-cell communication. In segmented animals such as annelids and arthropods, Wnt signalling is also likely involved in segment border formation and regionalisation of the segments. Priapulids represent unsegmented worms that are distantly related to arthropods. Despite their interesting phylogenetic position and their importance for the understanding of ecdysozoan evolution, priapulids still represent a highly underinvestigated group of animals. Here, we study the embryonic expression patterns of the complete sets of Wnt genes in the priapulids Priapulus caudatus and Halicryptus spinulosus. We find that both priapulids possess a complete set of 12 Wnt genes. At least in Priapulus, most of these genes are expressed in and around the posterior-located blastopore and thus likely play a role in posterior elongation. Together with previous work on the expression of other genetic factors such as caudal and even-skipped, this suggests that posterior elongation in priapulids is under control of the same (or very similar) conserved gene regulatory network as in arthropods.

中文翻译：

---

Priapulid Wnt基因的胚胎表达。

发育中的胚胎的后部伸长是动物发育的共同特征。一组与后延伸有关的基因由Wnt基因代表，Wnt基因是分泌的糖蛋白配体，向相邻细胞上的特定受体发出信号，从而建立了细胞与细胞之间的通讯。在节肢动物和节肢动物等节段动物中，Wnt信号也可能参与节段边界的形成和节段的区域化。Priapulids代表与节肢动物远缘的无节段蠕虫。尽管他们有趣的系统发育立场和对蜕皮动物进化的理解的重要性，但普利普利特仍然代表了一个研究不足的动物群。在这里，我们研究了完整的Wnt基因在priapulids中的胚胎表达模式Priapulus caudatus和Halicryptus spinulosus。我们发现两个普利亚普利特拥有一套完整的12个Wnt基因。至少在Priapulus中，大多数这些基因在位于后部的胚孔中及其周围表达，因此可能在后部延伸中起作用。连同先前关于其他遗传因子（例如尾状和均匀状）表达的研究，这表明，节肢动物中后节的伸长受节肢动物相同（或非常相似）保守的基因调控网络的控制。