Steingrímsson E, Pignoni F, Liaw G J, Lengyel J A
Department of Biology, University of California, Los Angeles 90024.
Science. 1991 Oct 18;254(5030):418-21. doi: 10.1126/science.1925599.
One of the first zygotically active genes required for formation of the terminal domains of the Drosophila embryo is tailless (tll). Expression of the tll gene is activated ectopically in gain-of-function mutants of the maternal terminal gene torso (tor); this suggests that tor normally activates the tll gene in the termini. Ectopic expression of tll under the control of an inducible promoter results in differentiation of ectopic terminal-specific structures, the Filzkörper, and leads to the activation of at least one gene, hunchback, that is required to form these structures. Ectopic expression of the tll gene also represses segmentation by repressing the gap genes Krüppel and knirps and probably also pair rule genes.
果蝇胚胎末端区域形成所需的最早的合子激活基因之一是无尾基因（tll）。在母体末端基因躯干（tor）的功能获得性突变体中，tll基因的表达被异位激活；这表明tor通常在末端激活tll基因。在可诱导启动子的控制下，tll的异位表达导致异位末端特异性结构Filzkörper的分化，并导致至少一个形成这些结构所需的基因驼背基因（hunchback）的激活。tll基因的异位表达还通过抑制间隙基因Krüppel和knirps以及可能的成对规则基因来抑制节段化。
