The segment-polarity gene engrailed is required for segmentation in the early Drosophila embryo. Loss of Engrailed function results in segmentation defects that vary in severity from pair-rule phenotypes to a lawn phenotype lacking in obvious of segmentation. During segmentation, Engrailed is expressed in stripes with a single segmental periodicity in Drosophila, which is conserved in all arthropods examined so far. To define segments, the segmental stripes of Engrailed induce the segmental stripes of wingless at each parasegmental boundary. However, segmentation functions of orthologs of engrailed in non-Drosophila arthropods have yet to be reported. Here, we analyzed functions of the Tribolium ortholog of engrailed (Tc-engrailed) during embryonic segmentation. Larval cuticles with Tc-engrailed being knocked down had segmentation phenotypes including incomplete segment formation and loss of a group of segments. In agreement with the cuticle segmentation defects, segments developed incompletely and irregularly or did not form in Tribolium germbands where Tc-engrailed was knocked down. Furthermore, knock-down of Tc-engrailed did not properly express the segmental stripes of wingless in Tribolium germbands. Taken together with the conserved expression patterns of Engrailed in arthropod segmentation, our data suggest that Tc-engrailed is required for embryonic segmentation in Tribolium, and the genetic mechanism of Engrailed inducing wingless expression is conserved at least between Drosophila and Tribolium.

中文翻译：

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Tribolium 分割中 engrailed 的功能分析

早期果蝇胚胎的分割需要嵌入的段极性基因。Engrailed 功能的丧失会导致严重程度不同的分割缺陷，从配对规则表型到缺乏明显分割的草坪表型。在分割期间，Engrailed 在果蝇中以具有单个节段周期性的条纹表示，这在迄今为止检查的所有节肢动物中都是保守的。为了定义节段，Engrailed 的节段条纹在每个节段旁边界诱导了无翼节段条纹。然而，非果蝇节肢动物中 engrailed 的直向同源物的分割功能尚未报道。在这里，我们分析了胚胎分割过程中 engrailed (Tc-engrailed) 的 Tribolium 直向同源物的功能。Tc-engrailed 被击倒的幼虫角质层具有分割表型，包括不完整的片段形成和一组片段的丢失。与角质层分割缺陷一致，在 Tc-engrailed 被击倒的 Tribolium 胚带中，片段发育不完全且不规则或未形成。此外，敲除 Tc-engrailed 不能正确表达 Tribolium 胚带中无翅的节段条纹。结合节肢动物分割中 Engrailed 的保守表达模式，我们的数据表明 Tc-engrailed 是 Tribolium 胚胎分割所必需的，并且 Engrailed 诱导无翼表达的遗传机制至少在果蝇和 Tribolium 之间是保守的。与角质层分割缺陷一致，在 Tc-engrailed 被击倒的 Tribolium 胚带中，片段发育不完全且不规则或未形成。此外，敲除 Tc-engrailed 不能正确表达 Tribolium 胚带中无翅的节段条纹。结合节肢动物分割中 Engrailed 的保守表达模式，我们的数据表明 Tc-engrailed 是 Tribolium 胚胎分割所必需的，并且 Engrailed 诱导无翼表达的遗传机制至少在果蝇和 Tribolium 之间是保守的。与角质层分割缺陷一致，在 Tc-engrailed 被击倒的 Tribolium 胚带中，片段发育不完全且不规则或未形成。此外，敲除 Tc-engrailed 不能正确表达 Tribolium 胚带中无翅的节段条纹。结合节肢动物分割中 Engrailed 的保守表达模式，我们的数据表明 Tc-engrailed 是 Tribolium 胚胎分割所必需的，并且 Engrailed 诱导无翼表达的遗传机制至少在果蝇和 Tribolium 之间是保守的。敲除 Tc-engrailed 不能正确表达 Tribolium 胚带中无翅的节段条纹。结合节肢动物分割中 Engrailed 的保守表达模式，我们的数据表明 Tc-engrailed 是 Tribolium 胚胎分割所必需的，并且 Engrailed 诱导无翼表达的遗传机制至少在果蝇和 Tribolium 之间是保守的。敲除 Tc-engrailed 不能正确表达 Tribolium 胚带中无翅的节段条纹。结合节肢动物分割中 Engrailed 的保守表达模式，我们的数据表明 Tc-engrailed 是 Tribolium 胚胎分割所必需的，并且 Engrailed 诱导无翼表达的遗传机制至少在果蝇和 Tribolium 之间是保守的。