Abstract：
The cellular and genetic networks that contribute to the development of the zeugopod (radius and ulna of the forearm, tibia and fibula of the leg) are not well understood, although these bones are susceptible to loss in congenital human syndromes and to the action of teratogens such as thalidomide. Using a new fate-mapping approach with the Chameleon transgenic chicken line, we show that there is a small contribution of SHH-expressing cells to the posterior ulna, posterior carpals and digit 3. We establish that although the majority of the ulna develops in response to paracrine SHH signalling in both the chicken and mouse, there are differences in the contribution of SHH-expressing cells between mouse and chicken as well as between the chicken ulna and fibula. This is evidence that, although zeugopod bones are clearly homologous according to the fossil record, the gene regulatory networks that contribute to their development and evolution are not fixed.
摘要：
有助于足足类动物发育的细胞和遗传网络，（前臂的桡骨和尺骨，腿部的胫骨和腓骨)没有很好地理解，尽管这些骨骼在先天性人类综合征中容易丢失，并且容易受到诸如沙利度胺之类的致畸剂的作用。使用变色龙转基因鸡系的新命运图方法，我们发现表达SHH的细胞对尺骨后部有很小的贡献，后腕骨和数字3。我们确定，虽然大多数尺骨在鸡和小鼠中都响应旁分泌SHH信号而发展，小鼠和鸡之间以及鸡尺骨和腓骨之间SHH表达细胞的贡献存在差异。这是证据，尽管根据化石记录，足足类骨骼显然是同源的，促进其发展和进化的基因调控网络并不固定。
