Translocation of a localized maternal mRNA to the vegetal pole of Xenopus oocytes
Translocation of a localized maternal mRNA to the vegetal pole of Xenopus oocytes
复制标题
局部母体 mRNA 易位至非洲爪蟾卵母细胞的植物极
作者：
D. Melton
胚胎学中一个突出的假设是，局部的母体因素在指定细胞命运中很重要。然而，只有少数母体分子被证明是局部化的，并且对这些因子如何在卵子中物理局部化知之甚少（参见参考文献1）。以前，cDNA克隆获得了一类本地化的母源mRNA非洲爪蟾2。这些mRNA是不寻常的，因为它们集中在未受精卵的动物或植物极。在本研究中，其中之一，Vg 1的合成和细胞内分布，已检查卵子发生过程中。结果表明，成熟卵母细胞中Vg1 mRNA呈新月形分布于植物极。令人惊讶的是，这种mRNA均匀分布在未成熟卵母细胞的细胞质中。这些发现表明，一个单一的细胞，青蛙卵母细胞，有一些机制易位特定的RNA，如Vg 1。移动Vgl mRNA的过程显然是不直接与Vgl RNA的合成偶联的细胞质定位机制。
A prominent hypothesis in embryology is that localized maternal factors are important in specifying cell fate. There are, however, only a few examples of maternal molecules that have been shown to be localized and very little is known about how such factors are physically localized within an egg (for review see ref. 1). Previously, cDNA clones were obtained for a class of localized maternal mRNAs from Xenopus laevis2. These mRNAs are unusual in that they are concentrated at either the animal or vegetal pole of unfertilized eggs. In the present study the synthesis and intracellular distribution of one of them, Vg1, has been examined during oogenesis. The results show that Vg1 mRNA is localized as a crescent at the vegetal pole of mature oocytes. Surprisingly, this mRNA is uniformly distributed in the cytoplasm of immature oocytes. These findings suggest that a single cell, the frog oocyte, has some mechanism for translocating specific RNAs like Vg1. The process that moves Vgl mRNA is evidently a cytoplasmic localization machinery which is not directly coupled to the synthesis of Vgl RNA.