Anterior patterning in animals is based on a gene regulatory network, which comprises highly conserved transcription factors like six3, pax6 and otx. More recently, foxQ2 was found to be an ancestral component of this network but its regulatory interactions showed evolutionary differences. In most animals, foxQ2 is a downstream target of six3 and knockdown leads to mild or no epidermal phenotypes. In contrast, in the red flour beetle Tribolium castaneum, foxQ2 gained a more prominent role in patterning leading to strong epidermal and brain phenotypes and being required for six3 expression. However, it has remained unclear which of these novel aspects were insect or arthropod specific. Here, we study expression and RNAi phenotype of the single foxQ2 ortholog of the spider Parasteatoda tepidariorum. We find early anterior expression similar to the one of insects. Further, we show an epidermal phenotype in the labrum similar to the insect phenotype. However, our data indicate that foxQ2 is positioned downstream of six3 like in other animals but unlike insects. Hence, the epidermal and neural pattering function of foxQ2 is ancestral for arthropods while the upstream role of foxQ2 may have evolved in the lineage leading to the insects.

中文翻译：

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six3在蜘蛛寄生天蛾的唇唇和神经发育中作用于foxQ2的上游。

动物的前部模式基于基因调控网络，该网络包含高度保守的转录因子，例如six3，pax6和otx。最近，发现foxQ2是该网络的祖先组件，但其调节相互作用显示出进化差异。在大多数动物，foxQ2是的下游目标SIX3和击倒导致轻微或没有表皮表型。相比之下，在红色的甲壳虫Tribolium castaneum中，foxQ2在模式形成中发挥了更为突出的作用，导致强烈的表皮和脑表型，并且是63所必需的。表达。然而，目前尚不清楚这些新颖方面中哪些是昆虫或节肢动物特异性的。在这里，我们研究蜘蛛拟天蛾的单个foxQ2直系同源基因的表达和RNAi表型。我们发现早期的前表达类似于昆虫之一。此外，我们在唇部显示了类似于昆虫表型的表皮表型。然而，我们的数据表明，foxQ2位于下游SIX3在其他动物，但不像昆虫等。因此，foxQ2的表皮和神经功能是节肢动物的祖先，而foxQ2的上游作用可能已在导致昆虫的谱系中进化。