Abzhanov A, Kaufman T C
Howard Hughes Medical Institute, Indiana University, Bloomington, Indiana 47405, USA.
Dev Biol. 2000 Nov 15;227(2):673-89. doi: 10.1006/dbio.2000.9904.
Studies of the genes involved in patterning the appendages of Drosophila melanogaster have revealed a system of signaling and transcriptional regulation that is responsible for specifying the proximo-distal limb axis. Here we report the expression patterns of presumptive homologs of the Drosophila genes extradenticle, dachshund, nubbin, ventral veins lacking (a.k.a. Cf1-a), and Dll in the limbs of the woodlouse Porcellio scaber and the spider Steatoda triangulosa. Although the expression domains of the appendage genes roughly correspond to those of Drosophila, their relative positions and segmental affiliation are distinct. In addition, the expression patterns of the appendage genes allows a resolution of the segmental composition of different appendages within crustacean and spider embryos. We conclude that certain limb types, e.g., mouthparts, appear to be derived from a leg-like ground-plan via the elimination/fusion of the intermediate and distal podomeres. Moreover, we observe just such a modification during the transformation of the anterior legs into mouthparts in P. scaber. Although our data do not unequivocally resolve the question of homology of the arthropod leg segments, they do provide evidence for a single conserved proximo-distal patterning system in the development of noninsect arthropod limbs.
对参与果蝇附肢模式形成的基因研究揭示了一个信号传导和转录调控系统，该系统负责确定附肢的近端-远端轴。在此，我们报告了果蝇基因extra denticle、腊肠犬基因、瘤状基因、缺腹静脉基因（又名Cf1-a）和Dll的假定同源物在潮虫鼠妇和三角肥腹蛛附肢中的表达模式。尽管这些附肢基因的表达域大致与果蝇的相对应，但其相对位置和节段归属是不同的。此外，附肢基因的表达模式有助于解析甲壳类和蜘蛛胚胎中不同附肢的节段组成。我们得出结论，某些附肢类型，如口器，似乎是通过中间和远端肢节的消除/融合从类似腿的基础模式衍生而来。此外，我们在鼠妇前腿向口器转变的过程中观察到了这样的一种变化。尽管我们的数据并未明确解决节肢动物腿节同源性的问题，但它们确实为非昆虫节肢动物附肢发育中单一保守的近端-远端模式形成系统提供了证据。
