Rushlow C, Frasch M, Doyle H, Levine M
Department of Biological Sciences, Fairchild Center, Columbia University, New York, New York 10027.
Nature. 1987;330(6148):583-6. doi: 10.1038/330583a0.
The homoeobox gene zerknüllt (zen) plays an important role in the differentiation of dorsal tissues during Drosophila development. zen- embryos show transformations in the dorsal-most regions of the fate map, and lack several tissues that normally derive from these regions, including the amnioserosa and optic lobe. zen displays a simple dorsal on/ventral off pattern as early as cleavage cycle 10-11 (ref. 2). We have prepared a polyclonal antibody against a full-length zen protein, and used this to examine its pattern of expression in mutants that disrupt dorsal-ventral polarity. Most or all of the maternally expressed genes that are involved in this process have been previously identified and fall into two classes, so called 'dorsalizers' and 'ventralizers' (see refs 4-7, reviewed in ref. 8). On the basis of our analysis of zen expression in each of these maternal mutants we propose that one or more of the dorsalizing genes encodes a repressor which inhibits the expression of zen in ventral regions of developing embryos. The ventralizing gene cactus might play an important role in restricting the activity of this repressor to ventral regions, thereby permitting the activation of zen in those dorsal tissues where its function is critically required.
同源异型框基因zerknüllt（zen）在果蝇发育过程中背侧组织的分化中起重要作用。zen突变体胚胎在命运图的最背侧区域出现转变，并且缺少几种通常源自这些区域的组织，包括羊膜浆膜和视叶。早在卵裂周期10 - 11时，zen就呈现出简单的背侧开启/腹侧关闭模式（参考文献2）。我们制备了一种针对全长zen蛋白的多克隆抗体，并利用它来检测其在破坏背腹极性的突变体中的表达模式。参与这一过程的大多数或所有母源表达基因先前已被鉴定，并分为两类，即所谓的“背化因子”和“腹化因子”（见参考文献4 - 7，参考文献8中有综述）。基于我们对每个这些母源突变体中zen表达的分析，我们提出一个或多个背化基因编码一种阻遏物，该阻遏物抑制发育中胚胎腹侧区域zen的表达。腹化基因仙人掌可能在将这种阻遏物的活性限制在腹侧区域中起重要作用，从而允许在那些对其功能至关重要的背侧组织中激活zen。
