Smolik-Utlaut S M
Division of Biology, California Institute of Technology, Pasadena.
Genetics. 1990 Feb;124(2):357-66. doi: 10.1093/genetics/124.2.357.
The wild-type Ultrabithorax (Ubx) and bithoraxoid (bxd) functions are primarily responsible for establishing the identity of parasegment 6 (PS6) in the Drosophila embryo and thus the identity of the posterior compartment of the third thoracic segment (pT3) and the anterior compartment of the first abdominal segment (aA1) in the adult. The experiments described were designed to test the ability of an increased dosage of Ubx+ and bxd+ to affect the transformation of PS5 toward PS6. The results are consistent with the ideas that (1) multiple copies of Ubx+ and bxd+ cause some cells within PS5 to take on the characteristics of PS6 cells but do not cause an overall parasegmental transformation of PS5 toward PS6, (2) cellular identity depends not only on the activity of Ubx+ but on its concentration as well, and (3) that an interaction between Ubx+ and the wild-type Antennapedia (Antp) gene establishes segmental identity in pT2. In the first instar larvae carrying eight copies of Ubx+ and bxd+ the fine hairs of the T3 setal belt are transformed toward the hook-like structures of the A1 setal belt. Other structures within this segment are unaffected. In the adult, the haltere is reduced in size. The transformation of pT2 cells (wing) toward pT3 cells (haltere) is seen in adults carrying eight doses of wild type Ubx and bxd by decreasing the amount of the bithorax complex (BX-C) regulator Polycomb (Pc). However, the transformation of the T3 setal belt is not enhanced in the larvae of these animals. The interaction between the genes of the Antennapedia complex (ANT-C) and the Ubx+ and bxd+ functions in pT2 is dosage sensitive only when the animals carry one copy of Pc. In these animals, the transformation of wing toward haltere is significantly enhanced.
野生型超双胸（Ubx）和双胸样（bxd）功能主要负责在果蝇胚胎中确立副节6（PS6）的特征，进而决定成虫中第三胸节的后区（pT3）和第一腹节的前区（aA1）的特征。所描述的实验旨在测试增加剂量的Ubx +和bxd +影响PS5向PS6转化的能力。结果与以下观点一致：（1）多个拷贝的Ubx +和bxd +使PS5内的一些细胞呈现PS6细胞的特征，但不会导致PS5整体向PS6的副节转化；（2）细胞特征不仅取决于Ubx +的活性，还取决于其浓度；（3）Ubx +与野生型触角足（Antp）基因之间的相互作用确立了pT2中的节段特征。在携带八个拷贝Ubx +和bxd +的一龄幼虫中，T3刚毛带的细毛向A1刚毛带的钩状结构转化。该节段内的其他结构未受影响。在成虫中，平衡棒尺寸减小。通过减少双胸复合体（BX-C）调节因子多梳（Pc）的量，在携带八剂量野生型Ubx和bxd的成虫中可见pT2细胞（翅膀）向pT3细胞（平衡棒）的转化。然而，这些动物幼虫中T3刚毛带的转化并未增强。触角足复合体（ANT-C）基因与pT2中的Ubx +和bxd +功能之间的相互作用仅在动物携带一个拷贝的Pc时对剂量敏感。在这些动物中，翅膀向平衡棒的转化显著增强。
