Nagy L M, Carroll S
Howard Hughes Medical Institute, Laboratory of Molecular Biology, University of Wisconsin, Madison 53706.
Nature. 1994 Feb 3;367(6462):460-3. doi: 10.1038/367460a0.
During embryogenesis, all insects reach a conserved, or phylotypic, stage at which all future segments are present. Different insects, however, arrive at this stage by overtly different pathways. In the long-germ insect Drosophila melanogaster, segmentation of the entire embryo occurs nearly simultaneously and results from the action of a cascade of transcriptional regulatory factors that operate in the acellular environment of the syncytial blastoderm. In short-germ insects, segmentation occurs in an anterior-to-posterior sequence, within a cellular environment, and might then be dependent on intercellular signalling. To compare the molecular mechanisms of segmentation, we have isolated a homologue of the Drosophila wingless gene, a mediator of cell-cell communications, from the short-germ beetle Tribolium castaneum. The principal features of wingless expression patterns in Drosophila are conserved in Tribolium, including its early deployment in rostral and caudal domains in the blastoderm, its segmental iteration in cells immediately anterior to cells expressing the engrailed gene, and its later restriction to a ventral sector of the developing appendages.
在胚胎发生过程中，所有昆虫都会进入一个保守的或系统发育型阶段，此时所有未来的体节都已形成。然而，不同的昆虫通过明显不同的途径达到这个阶段。在长胚型昆虫黑腹果蝇中，整个胚胎的分节几乎同时发生，这是由一系列转录调节因子在合胞体胚盘的无细胞环境中发挥作用的结果。在短胚型昆虫中，分节是在细胞环境中从前向后依次发生的，并且可能依赖于细胞间信号传导。为了比较分节的分子机制，我们从短胚型甲虫赤拟谷盗中分离出了果蝇无翅基因的一个同源物，该基因是细胞间通讯的介质。果蝇中无翅基因表达模式的主要特征在赤拟谷盗中是保守的，包括其在胚盘的头部和尾部区域的早期表达、在紧邻表达 engrailed 基因的细胞前方的细胞中的节段重复，以及其后期局限于发育中附肢的腹侧部分。
