Simmonds A J, Bell J B
Department of Biological Sciences, University of Alberta, Edmonton, Canada.
Genome. 1998 Jun;41(3):381-90. doi: 10.1139/g98-026.
The invected gene of Drosophila melanogaster is a homeobox-containing gene that is closely related to engrailed. A dominant gain of function allele, invectedDominant, was derived from mutagenesis of a dominant allele of vestigial, In(2R)vgW. A careful analysis of the phenotype of invectedDominant shows that it is associated with a transformation of the anterior compartment of the wing to a posterior fate. This transformation is normally limited to the wing blade itself and does not involve the remaining tissues derived from the wing imaginal disc, including the wing hinge and dorsal thorax of the fly. The ectopic expression of invected protein associated with invectedDominant correlates spatially with the normal expression pattern of vestigial in the wing imaginal disc, suggesting that control elements of vestigial are driving ectopic invected expression. This was confirmed by sequence analysis that shows that the dominant vestigial activity was eliminated by a deletion that removes the 3' portion of the vestigial coding region. This leaves a gene fusion wherein the vestigial enhancer elements are still juxtaposed immediately 5' to the invected transcriptional start site, but with the vg sequences harboring an additional lesion. Unlike recessive invected alleles, the invectedDominant allele produces an observable phenotype, and as such should prove useful in determining the role of invected in patterning the wing imaginal disc. Genetic analysis has shown that mutations of polyhomeotic, a gene involved in regulating engrailed expression, cause a reproducible alteration in the invectedDominant phenotype. Finally, the invectedDominant allele should prove valuable for identifying and characterizing genes that are activated within the posterior compartment. A screen using various lacZ lines that are asymmetrically expressed in an anterior-posterior manner in the wing imaginal disc isolated one line that shows posterior-specific expression within the transformed anterior compartment.
黑腹果蝇的invected基因是一个含同源异型框的基因，与engrailed密切相关。一个显性功能获得等位基因invectedDominant，源自对残翅显性等位基因In(2R)vgW的诱变。对invectedDominant表型的仔细分析表明，它与翅的前区向后命运的转变相关。这种转变通常仅限于翅片本身，并不涉及源自翅成虫盘的其余组织，包括果蝇的翅铰链和背胸。与invectedDominant相关的invected蛋白的异位表达在空间上与翅成虫盘中残翅的正常表达模式相关，这表明残翅的调控元件驱动了invected的异位表达。序列分析证实了这一点，该分析表明通过缺失残翅编码区的3'部分消除了显性残翅活性。这留下了一个基因融合体，其中残翅增强子元件仍紧邻invected转录起始位点的5'端，但vg序列带有额外的损伤。与隐性invected等位基因不同，invectedDominant等位基因产生可观察到的表型，因此在确定invected在翅成虫盘图案形成中的作用方面应该是有用的。遗传分析表明，参与调节engrailed表达的多同源异型基因的突变会导致invectedDominant表型发生可重复的改变。最后，invectedDominant等位基因在鉴定和表征在后区被激活的基因方面应该是有价值的。使用在翅成虫盘中以前后不对称方式表达的各种lacZ品系进行的筛选分离出了一个品系，该品系在转化的前区显示出后特异性表达。
