Vincent A, Blankenship J T, Wieschaus E
Department of Molecular Biology, Princeton University, New Jersey 08540, USA.
Development. 1997 Oct;124(19):3747-54. doi: 10.1242/dev.124.19.3747.
Genetic and molecular analyses of patterning of the Drosophila embryo have shown that the process of segmentation of the head is fundamentally different from the process of segmentation of the trunk. The cephalic furrow (CF), one of the first morphological manifestations of the patterning process, forms at the juxtaposition of these two patterning systems. We report here that the initial step in CF formation is a change in shape and apical positioning of a single row of cells. The anteroposterior position of these initiator cells may be defined by the overlapping expression of the head gap gene buttonhead (btd) and the primary pair-rule gene even-skipped (eve). Re-examination of the btd and eve phenotypes in live embryos indicated that both genes are required for CF formation. Further, Eve expression in initiator cells was found to be dependent upon btd activity. The control of eve expression by btd in these cells is the first indication of a new level of integrated regulation that interfaces the head and trunk segmentation systems. In conjunction with previous data on the btd and eve embryonic phenotypes, our results suggest that interaction between these two genes both controls initiation of a specific morphogenetic movement that separates two morphogenetic fields and contributes to patterning the hinge region that demarcates the procephalon from the segmented germ band.
对果蝇胚胎模式形成的遗传学和分子分析表明，头部的分节过程与躯干的分节过程根本不同。头部沟（CF）是模式形成过程中最早的形态学表现之一，在这两个模式形成系统的并列处形成。我们在此报告，CF形成的初始步骤是单列细胞的形状和顶端定位的改变。这些起始细胞的前后位置可能由头部间隙基因钮头（btd）和初级成对规则基因偶数跳动（eve）的重叠表达所定义。对活胚胎中btd和eve表型的重新检查表明，这两个基因都是CF形成所必需的。此外，发现起始细胞中的Eve表达依赖于btd活性。btd在这些细胞中对eve表达的控制是连接头部和躯干分节系统的新水平整合调控的第一个迹象。结合先前关于btd和eve胚胎表型的数据，我们的结果表明，这两个基因之间的相互作用既控制了将两个形态发生场分开的特定形态发生运动的起始，又有助于对将前脑与分节胚带区分开的铰链区域进行模式化。
