Panzer S, Weigel D, Beckendorf S K
Department of Molecular and Cell Biology, University of California, Berkeley 94720.
Development. 1992 Jan;114(1):49-57. doi: 10.1242/dev.114.1.49.
We have investigated Drosophila salivary gland determination by examining the effects of mutations in pattern forming genes on the salivary gland primordium. We find that the anterior-posterior extent of the primordium, a placode of columnar epithelial cells derived from parasegment 2, is established by the positive action of the homeotic gene Sex combs reduced (Scr). Embryos mutant for Scr lack a detectable placode, while ectopic Scr expression leads to the formation of ectopic salivary glands. In contrast, the dorsal-ventral extent of the placode is regulated negatively. Functions dependent on the decapentaplegic product place a dorsal limit on the placode, while dorsal-dependent genes act to limit the placode ventrally. We propose a model in which these pattern forming genes act early to determine the salivary gland anlage by regulating the expression of salivary gland determining genes, which in turn control genes that are involved in salivary gland morphogenesis.
我们通过研究模式形成基因的突变对唾液腺原基的影响，来探究果蝇唾液腺的决定机制。我们发现，原基（源自副节2的柱状上皮细胞基板）的前后范围是由同源异型基因“性梳减少”（Scr）的正向作用所确立的。Scr突变的胚胎缺乏可检测到的基板，而异位表达Scr则会导致异位唾液腺的形成。相比之下，基板的背腹范围受到负调控。依赖于“五体不全”产物的功能对基板设定了一个背侧界限，而依赖于背侧的基因则起到在腹侧限制基板的作用。我们提出了一个模型，其中这些模式形成基因早期发挥作用，通过调节唾液腺决定基因的表达来确定唾液腺原基，而唾液腺决定基因反过来控制参与唾液腺形态发生的基因。
