Smoliński Dariusz Jan, Kołowerzo Agnieszka
Department of Cell Biology, Institute of General and Molecular Biology, Nicolaus Copernicus University, Gagarina 9, 87-100 Toruń, Poland.
Chromosoma. 2012 Feb;121(1):37-48. doi: 10.1007/s00412-011-0339-4. Epub 2011 Sep 10.
In microsporocytes of the European larch, we demonstrated the presence of several mRNAs in spherical nuclear bodies. In the nuclei of microsporocytes, we observed up to 12 bodies, ranging from 0.5 to 6 μm in diameter, during the prophase of the first meiotic division. Our previous studies revealed the presence of polyadenylated RNA (poly(A) RNA) in these bodies, but did not confirm the presence of nascent transcripts or splicing factors of the SR family. The lack of these molecules precludes the bodies from being the sites of synthesis and early maturation of primary transcripts (Kołowerzo et al., Protoplasma 236:13-19, 2009). However, the bodies serve as sites for the accumulation of splicing machinery, including the Sm proteins and small nuclear RNAs. Characteristic ultrastructures and the molecular composition of the nuclear bodies, which contain poly(A) RNA, are indicative of Cajal bodies (CBs). Here, we demonstrated the presence of several housekeeping gene transcripts--α-tubulin, pectin methylesterase, peroxidase and catalase, ATPase, and inositol-3-phosphate synthase--in CBs. Additionally, we observed transcripts of the RNA polymerase II subunits RPB2 and RPB10 RNA pol II and the core spliceosome proteins mRNA SmD1, SmD2, and SmE. The co-localization of nascent transcripts and mRNAs indicates that mRNA accumulation/storage, particularly in CBs, occurs in the nucleus of microsporocytes.
在欧洲落叶松的小孢子母细胞中，我们证明了球形核小体中存在几种mRNA。在小孢子母细胞的细胞核中，我们在第一次减数分裂前期观察到多达12个核小体，直径从0.5到6μm不等。我们之前的研究揭示了这些核小体中存在聚腺苷酸化RNA（poly(A) RNA），但未证实新生转录本或SR家族剪接因子的存在。这些分子的缺失排除了核小体作为初级转录本合成和早期成熟位点的可能性（Kołowerzo等人，《原生质体》236:13 - 19，2009）。然而，这些核小体是剪接机制积累的位点，包括Sm蛋白和小核RNA。含有poly(A) RNA的核小体的特征性超微结构和分子组成表明其为卡哈尔体（CBs）。在这里，我们证明了CBs中存在几种管家基因转录本——α - 微管蛋白、果胶甲酯酶、过氧化物酶和过氧化氢酶、ATP酶以及肌醇 - 3 - 磷酸合酶。此外，我们观察到RNA聚合酶II亚基RPB2和RPB10 RNA pol II以及核心剪接体蛋白mRNA SmD1、SmD2和SmE的转录本。新生转录本和mRNA的共定位表明mRNA积累/储存，特别是在CBs中，发生在小孢子母细胞的细胞核中。
