Strasser Markus J, Mackenzie Natalia C, Dumstrei Karin, Nakkrasae La-Iad, Stebler Jürg, Raz Erez
Germ Cell Development, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
BMC Dev Biol. 2008 May 28;8:58. doi: 10.1186/1471-213X-8-58.
Zebrafish germ cells contain granular-like structures, organized around the cell nucleus. These structures share common features with polar granules in Drosophila, germinal granules in Xenopus and chromatoid bodies in mice germ cells, such as the localization of the zebrafish Vasa, Piwi and Nanos proteins, among others. Little is known about the structure of these granules as well as their segregation in mitosis during early germ-cell development.
Using transgenic fish expressing a fluorescently labeled novel component of Zebrafish germ cell granules termed Granulito, we followed the morphology and distribution of the granules. We show that whereas these granules initially exhibit a wide size variation, by the end of the first day of development they become a homogeneous population of medium size granules. We investigated this resizing event and demonstrated the role of microtubules and the minus-end microtubule dependent motor protein Dynein in the process. Last, we show that the function of the germ cell granule resident protein the Tudor domain containing protein-7 (Tdrd7) is required for determination of granule morphology and number.
Our results suggest that Zebrafish germ cell granules undergo a transformation process, which involves germ cell specific proteins as well as the microtubular network.
斑马鱼生殖细胞含有围绕细胞核组织的颗粒状结构。这些结构与果蝇中的极性颗粒、非洲爪蟾中的生殖颗粒以及小鼠生殖细胞中的类染色质体具有共同特征，例如斑马鱼Vasa、Piwi和Nanos蛋白等的定位。关于这些颗粒的结构以及它们在早期生殖细胞发育过程中在有丝分裂期间的分离情况知之甚少。
利用表达一种名为Granulito的斑马鱼生殖细胞颗粒的新型荧光标记成分的转基因鱼，我们追踪了这些颗粒的形态和分布。我们发现，虽然这些颗粒最初呈现出广泛的大小差异，但在发育第一天结束时，它们变成了中等大小颗粒的同质群体。我们研究了这种大小调整事件，并证明了微管和负端微管依赖性运动蛋白动力蛋白在此过程中的作用。最后，我们表明生殖细胞颗粒驻留蛋白含Tudor结构域蛋白7（Tdrd7）的功能对于确定颗粒形态和数量是必需的。
我们的结果表明，斑马鱼生殖细胞颗粒经历了一个转化过程，这涉及生殖细胞特异性蛋白以及微管网络。
