Three-dimensional ultrastructural analysis of RNA distribution within germinal granules of xenopus
Three-dimensional ultrastructural analysis of RNA distribution within germinal granules of xenopus
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DOI：
10.1006/dbio.2001.0488
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发表时间：
2002-01-01
影响因子：
2.7
通讯作者：
Etkin, LD
中科院分区：
文献类型：
--
作者：
Kloc, M;Dougherty, MT;Etkin, LD
生殖质是卵母细胞细胞质的一个特殊区域，它包含生殖细胞命运的决定因素。在爪蟾卵母细胞中，胚质是线粒体云METRO区域的一部分。它含有生发颗粒和各种编码和非编码rna，包括Xcat2、Xlsirts、Xdazl、DEADSouth、Xpat、Xwnt11、fatVg、B7/Fingers、C10/XFACS和线粒体大rna和小rna。利用全贴装电镜原位杂交技术分析了这11种不同rna在爪蟾卵发生和发育过程中在种质不同区室中的分布。利用连续电镜切片重建云METRO区域内生发颗粒分布的三维图像，以及卵母细胞和胚胎中颗粒上rna的分布。我们发现，在卵母细胞中，大多数rna要么与生发颗粒的前体有关，要么与胚质基质有关。卵母细胞中只有Xcat2、Xpat和DEADSouth rna与成熟的生发颗粒相关，而胚胎中只有Xcat2和Xpat rna与生发颗粒相关。然而，Xcat2是唯一始终被隔离在生发颗粒内的RNA，而其他RNA则位于外围。在颗粒间基质上检测到参与生殖细胞迁移/形成的Xdazl。在发育后期，Xcat2 mRNA从生发颗粒中释放出来。这与它的翻译抑制的时间一致。这些结果表明，在卵发生和发育过程中，生发颗粒具有动态的三维结构。他们还表明，特定rna与生发颗粒的结合并不是它们服务于生殖细胞功能的先决条件；然而，这可能与它们的翻译抑制状态有关。(C) 2001 Elsevier Science。
The germ plasm is a specialized region of oocyte cytoplasm that contains determinants of germ cell fate. In Xenopus oocytes, the germ plasm is a part of the METRO region of mitochondrial cloud. It contains the germinal granules and a variety of coding and noncoding RNAs that include Xcat2, Xlsirts, Xdazl, DEADSouth, Xpat, Xwnt11, fatVg, B7/Fingers, C10/XFACS, and mitochondrial large and small rRNA. We analyzed the distribution of these 11 different RNAs within the various compartments of germ plasm during Xenopus oogenesis and development by using whole-mount electron microscopy in situ hybridization. Serial EM sections were used to reconstruct a three-dimensional image of germinal granule distribution within the METRO region of the cloud and the distribution of RNAs on the granules in oocytes and embryos. We found that, in the oocytes, the majority of RNAs were associated either with the precursor of germinal granules or with the germ plasm matrix. Only Xcat2, Xpat, and DEADSouth RNAs were associated with the mature germinal granules in oocytes, while only Xcat2 and Xpat were associated with germinal granules in embryos. However, Xcat2 was the only RNA that was consistently sequestered inside the germinal granules, while the others were located on the periphery. Xdazl, which functions in germ cell migration/formation, was detected on the matrix between granules. Later in development, Xcat2 mRNA was released from the germinal granules. This coincides with the timing of its translational derepression. These results demonstrate that there is a dynamic three-dimensional architecture to the germinal granules that changes during oogenesis and development. They also indicate that association of specific RNAs with the germinal granules is not a prerequisite for their serving a germ cell function; however, it may be related to their state of translational repression. (C) 2001 Elsevier Science.