Department of Entomology, 4291 Fieldhouse Drive, University of Maryland, College Park, MD 20742, USA.
Department of Entomology, 4291 Fieldhouse Drive, University of Maryland, College Park, MD 20742, USA
Development. 2019 Sep 10;146(17):dev181453. doi: 10.1242/dev.181453.
The discovery of pair-rule genes (PRGs) in revealed the existence of an underlying two-segment-wide prepattern directing embryogenesis. The milkweed bug , a hemimetabolous insect, is a more representative arthropod: most of its segments form sequentially after gastrulation. Here, we report the expression and function of orthologs of the complete set of nine PRGs in Seven -PRG-orthologs are expressed in stripes in the primordia of every segment, rather than every other segment; is PR-like and several orthologs are also expressed in the segment addition zone. RNAi-mediated knockdown of , and impacted all segments, with no indication of PR-like register. We confirm that - is expressed in PR-like stripes, although it is not expressed in this way in , demonstrating the existence of an underlying PR-like prepattern in These findings reveal that a switch occurred in regulatory circuits, leading to segment formation: while several holometabolous insects are '-like', using PRG orthologs for PR patterning, most PRGs are expressed segmentally in , a more basally branching insect. Thus, an evolutionarily stable phenotype - segment formation - is directed by alternate regulatory pathways in diverse species.
在果蝇中发现的成对规则基因 (PRGs) 揭示了存在一个基本的双节段预图案来指导胚胎发生。 作为半变态昆虫的乳草虫是一种更具代表性的节肢动物：其大多数体节在原肠胚形成后顺序形成。 在这里，我们报告了完整的九组 PRG 的同源物在 中的表达和功能。 七个-PRG-同源物在每个体节的原基中呈条纹状表达，而不是每隔一个体节表达； 类似于 PR，并且几个同源物也在体节添加区表达。 通过 RNAi 介导的 、 和 的敲低影响了所有体节，没有 PR 样注册的迹象。 我们确认 - 在 PR 样条纹中表达，尽管它在 中不是以这种方式表达，这表明在 中存在潜在的 PR 样预图案。 这些发现揭示了调控回路中的一个开关发生了，导致了体节的形成：虽然几个全变态昆虫是“-样”的，使用 PRG 同源物进行 PR 图案形成，但大多数 PRG 在 中呈节段性表达，这是一种分支更基础的昆虫。 因此，在不同物种中，一种进化稳定的表型——体节形成——是由替代的调控途径指导的。
