GENETIC ANALYSIS OF POLARITY

果蝇模式形成的一个关键步骤是 沿着两个主要身体轴沿着建立极性。 至少20 母性活跃基因参与产生背腹极性。 多种实验表明，背侧代表最后一步 在此过程中，它作为腹侧形态发生素， 合子基因组的位置信息。 我们已经克隆和 对背侧基因进行了表征，发现它与 脊椎动物原癌基因c-rel。 在野生型胚胎中， 蛋白质在分裂期间存在于细胞质中。 在原子核之后 迁移到胚胎的周边，腹到背的梯度， 建立了核背蛋白。 核的形成 在来自其他母系活跃的突变胚胎中， 背腹极性基因 在背化突变胚胎中，只有 细胞质蛋白，而在腹侧胚胎， 核梯度向背侧移动。 背侧再定位 从细胞质到细胞核的蛋白质对于背侧到 作为形态发生素发挥作用。 我们提出了一些实验，解决两个基本的 问题（1）核梯度是如何形成的，有哪些因素 参与，以及（2）背如何发挥其功能作为一个形态。

A critical step in pattern formation in Drosophila is the establishment of polarity along the two major body axes. At least 20 maternally active genes are involved in creating dorsal-ventral polarity. A variety of experiments have shown that dorsal represents the last step in the process, it acts as the ventral morphogen relating the maternal positional information to the zygotic genome. We have cloned and characterized the dorsal gene and found it is closely related to the vertebrate proto-oncogene c-rel. In wild-type embryos, the dorsal protein is present in the cytoplasm during cleavage. After the nuclei migrate to the periphery of the embryo, a ventral-to-dorsal gradient of nuclear dorsal protein is established. The formation of the nuclear gradient is disrupted in mutant embryos from other maternally active dorsal-ventral polarity genes. In dorsalized mutant embryos, only cytoplasmic protein is observed, while in ventralized embryos, the nuclear gradient is shifted dorsally. Relocalization of the dorsal protein from the cytoplasm to the nucleus appears critical for dorsal to function as a morphogen. We propose a number of experiments that address the two basic questions of (1) how is the nuclear gradient formed and what factors are involved, and (2) how does dorsal exert its function as a morphogen.