In the vinegar fly Drosophila melanogaster, the homeodomain containing transcription factor Teashirt (Tsh) appears to specify trunk identity in concert with the function of the Hox genes. While in Drosophila there is a second gene closely related to tsh, called tiptop (tio), in other arthropods species only one copy exists (called tio/tsh). The expression of tsh and tio/tsh, respectively, is surprisingly similar among arthropods suggesting that its function as trunk selector gene may be conserved. Other research, for example on the beetle Tribolium castaneum, questions even conservation of Tsh function among insects. The zinc-finger transcription factor Spalt (Sal) is involved in the regulation of Drosophila tsh, but this regulatory interaction does not appear to be conserved in Tribolium either. Whether the function and interaction of tsh and sal as potential trunk-specifiers, however, is conserved is still unclear because comparative studies on sal expression (except for Tribolium) are lacking, and functional data are (if at all existing) restricted to Insecta. Here, we provide additional data on arthropod tsh expression, show the first data on onychophoran tio/tsh expression, and provide a comprehensive investigation on sal expression patterns in arthropods and an onychophoran. Our data support the idea that tio/tsh genes are involved in the development of “trunk” segments by regulating limb development. Our data suggest further that the function of Sal is indeed unlikely to be conserved in trunk vs head development like in Drosophila, but early expression of sal is in line with a potential homeotic function, at least in Arthropoda.

中文翻译：

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Panarthropod顶呱呱/ teashirt和施帕尔特同源物以及其作为“树干” -selector基因的潜在作用

在醋蝇 Drosophila melanogaster 中，含有转录因子 Teashirt (Tsh) 的同源域似乎指定了与 Hox 基因功能一致的躯干身份。虽然在果蝇中有第二个与 tsh 密切相关的基因，称为tiptop (tio)，但在其他节肢动物物种中只存在一个副本（称为 tio/tsh）。tsh 和 tio/tsh 的表达分别在节肢动物中惊人地相似，表明其作为躯干选择基因的功能可能是保守的。其他研究，例如甲虫 Tribolium castaneum，甚至质疑昆虫中 Tsh 功能的保护。锌指转录因子 Spalt (Sal) 参与果蝇 tsh 的调节，但这种调节相互作用在 Tribolium 中似乎也不保守。然而，tsh 和 sal 作为潜在主干说明符的功能和相互作用是否保守仍不清楚，因为缺乏对 sal 表达（Tribolium 除外）的比较研究，并且功能数据（如果有的话）仅限于昆虫纲。在这里，我们提供了关于节肢动物 tsh 表达的额外数据，展示了关于有爪动物 tio/tsh 表达的第一个数据，并对节肢动物和有爪动物的 Sal 表达模式进行了全面调查。我们的数据支持 tio/tsh 基因通过调节肢体发育参与“躯干”节段发育的观点。我们的数据进一步表明，Sal 的功能确实不太可能像果蝇那样在躯干与头部发育中保守，但 Sal 的早期表达符合潜在的同源异型功能，至少在节肢动物中如此。