Evolution of morphogenesis is generally associated with changes in genetic regulation. Here, we report evidence indicating that dorsal closure, a conserved morphogenetic process in dipterans, evolved as the consequence of rearrangements in epithelial organization rather than signaling regulation. In Drosophila melanogaster, dorsal closure consists of a two-tissue system where the contraction of extraembryonic amnioserosa and a JNK/Dpp-dependent epidermal actomyosin cable result in microtubule-dependent seaming of the epidermis. We find that dorsal closure in Megaselia abdita, a three-tissue system comprising serosa, amnion and epidermis, differs in morphogenetic rearrangements despite conservation of JNK/Dpp signaling. In addition to an actomyosin cable, M. abdita dorsal closure is driven by the rupture and contraction of the serosa and the consecutive microtubule-dependent seaming of amnion and epidermis. Our study indicates that the evolutionary transition to a reduced system of dorsal closure involves simplification of the seaming process without changing the signaling pathways of closure progression.

中文翻译：

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两个连续的基于微管的上皮缝合事件介导了天窗苍蝇 Megaselia abdita 的背闭合

形态发生的进化通常与遗传调控的变化有关。在这里，我们报告的证据表明，双翅目中保守的形态发生过程背侧闭合是上皮组织重排的结果，而不是信号调节的结果。在黑腹果蝇中，背侧闭合由两个组织系统组成，其中胚胎外羊膜的收缩和依赖 JNK/Dpp 的表皮肌动蛋白电缆导致表皮的微管依赖接缝。我们发现 Megaselia abdita 的背侧闭合，包括浆膜、羊膜和表皮的三组织系统，尽管 JNK/Dpp 信号的保守性在形态发生重排上有所不同。除了肌动球蛋白电缆，M. abdita 背侧闭合是由浆膜的破裂和收缩以及羊膜和表皮的连续微管依赖接缝驱动的。我们的研究表明，向减少的背侧闭合系统的进化过渡涉及缝合过程的简化，而不改变闭合过程的信号通路。