Ray K, Rodrigues V
Molecular Biology Unit, Tata Institute of Fundamental Research, Colaba, Bombay, India.
Dev Biol. 1995 Feb;167(2):426-38. doi: 10.1006/dbio.1995.1039.
The olfactory sensilla on the antenna of adult Drosophila melanogaster develop during the first 36 hr after pupariation, from their anlagen in the cephalic disc. We have used tissue-specific beta-galactosidase expression in the enhancer trap strain A101.IF3 and the monoclonal antibody 22C10 as sensory cell markers, as well as the lineage tracer 5-bromo-2'-deoxyuridine (BrdU), to describe this process. The development of an olfactory sensillum begins with the selection of a "founder cell" (FC). These cells are distinct in that they possess large apically located nuclei revealed by beta-galactosidase expression in A101.IF3. In the following 6 hr, a few cells neighboring the FC also start expressing beta-galactosidase and together comprise a group. Cells of this group, denoted a "presensillum-cluster" (PSC), undergo at least one round of replication and give rise to all of the cells of a sensillum. A subset of the cells within each PSC and, later, all the sensory neurons are recognized by MAb22C10. The antennae of the mutant lozenge3 (lz3) lack all basiconic and some trichoid sensilla. The mutation apparently affects early steps in sensillum development and many of the FCs fail to form. Those that are present, however, proceed to form mature olfactory sensilla. Therefore, we conclude that the selection of an FC is the first step in olfactory sense organ development. Our study reveals novel aspects of sensory development in Drosophila.
成年黑腹果蝇触角上的嗅觉感器在化蛹后的头36小时内从头部盘中的原基开始发育。我们利用增强子陷阱品系A101.IF3中的组织特异性β-半乳糖苷酶表达、单克隆抗体22C10作为感觉细胞标记以及谱系示踪剂5-溴-2'-脱氧尿苷（BrdU）来描述这一过程。嗅觉感器的发育始于“奠基细胞”（FC）的选择。这些细胞的独特之处在于，它们具有大的位于顶端的细胞核，这可通过A101.IF3中的β-半乳糖苷酶表达显示出来。在接下来的6小时内，一些与FC相邻的细胞也开始表达β-半乳糖苷酶，并共同组成一个群体。这个群体的细胞，称为“前感器簇”（PSC），至少经历一轮复制，并产生一个感器的所有细胞。每个PSC内的一部分细胞，以及后来所有的感觉神经元都能被单克隆抗体22C10识别。突变体菱形3（lz3）的触角缺少所有的锥形感器和一些毛形感器。该突变显然影响感器发育的早期步骤，许多FC未能形成。然而，那些存在的FC会继续形成成熟的嗅觉感器。因此，我们得出结论，FC的选择是嗅觉感觉器官发育的第一步。我们的研究揭示了果蝇感觉发育的新方面。
