Martin Sophie G, Leclerc Vincent, Smith-Litière Katie, St Johnston Daniel
The Wellcome Trust/Cancer Research UK Institute and the Department of Genetics, University of Cambridge, Tennis Court Rd, Cambridge CB2 1QR, UK.
Development. 2003 Sep;130(17):4201-15. doi: 10.1242/dev.00630.
The anteroposterior axis of Drosophila is defined during oogenesis, when the polarisation of the oocyte microtubule cytoskeleton directs the localisation of bicoid and oskar mRNAs to the anterior and posterior poles, respectively. Although maternal-effect lethal and female-sterile screens have identified many mutants that disrupt these processes, these screens could not recover mutations in essential genes. Here we describe a genetic screen in germline clones for mutants that disrupt the localisation of GFP-Staufen in living oocytes, which overcomes this limitation. As Staufen localises to the posterior with oskar mRNA and to the anterior with bicoid mRNA, it acts as a marker for both poles of the oocyte, allowing the identification of mutants that affect the localisation of either mRNA, as well as mutants that disrupt oocyte polarity. Using this approach, we have identified 23 novel complementation groups on chromosome 3R that disrupt anteroposterior axis formation. Analyses of new alleles of spn-E and orb show that both SPN-E and ORB proteins are required to organise the microtubule cytoskeleton at stage 9, and to prevent premature cytoplasmic streaming. Furthermore, yps mutants partially suppress the premature cytoplasmic streaming of orb mutants. As orb, yps and spn-E encode RNA-binding proteins, they may regulate the translation of unidentified RNAs necessary for the polarisation of the microtubule cytoskeleton.
果蝇的前后轴在卵子发生过程中得以确定，此时卵母细胞微管细胞骨架的极化分别将双尾和 Oskar 信使核糖核酸定位到前后两极。尽管母性效应致死和雌性不育筛选已经鉴定出许多破坏这些过程的突变体，但这些筛选无法发现必需基因中的突变。在此，我们描述了一种在生殖系克隆中针对破坏活卵母细胞中绿色荧光蛋白 - 斯陶芬定位的突变体进行的遗传筛选，该筛选克服了这一限制。由于斯陶芬与 Oskar 信使核糖核酸一起定位到后部，与双尾信使核糖核酸一起定位到前部，它充当卵母细胞两极的标记，从而能够鉴定影响任一信使核糖核酸定位的突变体，以及破坏卵母细胞极性的突变体。使用这种方法，我们在 3R 染色体上鉴定出 23 个破坏前后轴形成的新互补群。对 spn - E 和 orb 的新等位基因的分析表明，SPN - E 和 ORB 蛋白在第 9 阶段都是组织微管细胞骨架以及防止过早细胞质流动所必需的。此外，yps 突变体部分抑制 orb 突变体的过早细胞质流动。由于 orb、yps 和 spn - E 编码 RNA 结合蛋白，它们可能调节微管细胞骨架极化所需的未鉴定 RNA 的翻译。
