Lawrence P A, Johnston P
MRC Laboratory of Molecular Biology, Cambridge, UK.
Development. 1989 Apr;105(4):761-7. doi: 10.1242/dev.105.4.761.
The first sign of metamerization in the Drosophila embryo is the striped expression of pair-rule genes such as fushi tarazu (ftz) and even-skipped (eve). Here we describe, at cellular resolution, the development of ftz and eve protein stripes in staged Drosophila embryos. They appear gradually, during the syncytial blastoderm stage and soon become asymmetric, the anterior margins of the stripes being sharply demarcated while the posterior borders are undefined. By the beginning of germ band elongation, the eve and ftz stripes have narrowed and become very intense at their anterior margins. The development of these stripes in hairy-, runt-, eve-, ftz- and engrailed- embryos is illustrated. In eve- embryos, the ftz stripes remain symmetric and lack sharp borders. Our results support the hypothesis (Lawrence et al. Nature 328, 440-442, 1987) that individual cells are allocated to parasegments with respect to the anterior margins of the eve and ftz stripes.
果蝇胚胎分节的首个迹象是成对规则基因（如分节基因和偶数缺口基因）的条纹状表达。在此，我们以细胞分辨率描述了不同发育阶段果蝇胚胎中分节基因和偶数缺口基因蛋白质条纹的发育情况。它们在合胞体胚盘阶段逐渐出现，很快变得不对称，条纹的前缘界限清晰，而后缘则不明确。到胚带伸长开始时，偶数缺口基因和分节基因的条纹变窄，且在前缘变得非常明显。文中展示了毛状基因、矮胖基因、偶数缺口基因、分节基因和 engrailed 基因胚胎中这些条纹的发育情况。在偶数缺口基因突变胚胎中，分节基因条纹保持对称且缺乏清晰边界。我们的结果支持了这样一个假说（劳伦斯等人，《自然》328 卷，440 - 442 页，1987 年），即相对于偶数缺口基因和分节基因条纹的前缘，单个细胞被分配到副节中。
