Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, Japan.
Science. 2013 Apr 26;340(6131):495-8. doi: 10.1126/science.1234219. Epub 2013 Mar 14.
Fossil insects living some 300 million years ago show winglike pads on all thoracic and abdominal segments, which suggests their serial homology. It remains unclear whether winglike structures in nonwinged segments have been lost or modified through evolution. Here, we identified a ventral lateral part of the body wall on the first thoracic segment, the hypomeron, and pupal dorsolateral denticular outgrowths as wing serial homologs in the mealworm beetle Tenebrio molitor. Both domains transform into winglike structures under Hox RNA interference conditions. Gene expression and functional analyses revealed central roles for the key wing selector genes, vestigial and scalloped, in the hypomeron and the denticular outgrowth formation. We propose that modification, rather than loss, of dorsal appendages has provided an additional diversifying mechanism of insect body plan.
生活在约 3 亿年前的化石昆虫在所有胸节和腹节上都显示出翼状的肩板，这表明它们具有系列同源性。目前尚不清楚非翅节的翼状结构是在进化过程中丢失还是被修改了。在这里，我们鉴定了鞘翅目拟步行甲科幼虫第一胸节的体壁腹侧外侧部分，即后体节，以及蛹背侧齿状突起作为拟步行甲科幼虫的翅系列同源物。这两个结构域在 Hox RNA 干扰条件下都转化为翼状结构。基因表达和功能分析表明，关键的翅选择基因，vestigial 和 scalloped，在后体节和齿状突起的形成中起着核心作用。我们提出，背部附肢的修饰，而不是丢失，为昆虫体节的多样化提供了另一种机制。
