泥鳅核糖体基因（泥鳅）的组织。

Organization of loach ribosomal genes (Misgurnus fossilis L.).

作者信息

Kuprijanova N, Popenko V, Eisner G, Vengerov J, Timofeeva M, Tikhonenko A, Skryabin K, Bayev A

出版信息

Mol Biol Rep. 1982 Apr 16;8(3):143-8. doi: 10.1007/BF00777241.

Abstract

The organization of ribosomal genes in the genome and amplified nucleoli of loach (Misgurnus fossilis L.), a teleost fish, was studied. Ribosomal DNA (rDNA) was isolated by density gradient centrifugation, digested by EcoRI endonuclease and mapped with 18S and 28S rRNAs. The transcription unit of ribosomal genes in oocyte nucleoli was investigated by an electron-microscopic visualization technique. The repeat unit of loach rDNA was shown to be split by EcoRI into two fragments: a constant fragment (3 . 10(6) daltons) and heterogeneous one (11-13 . 10(6) daltons, major type, and 7-8 . 10(6) daltons, minor type). The average size of the transcription units was found to be 2.5 +/- 0.2 microm. The lengths of nontranscribed spacers varied from 2.4 to 2.9 microm; however, shorter ones of 1.2-1.4 microm were also noticed. The data indicate that loach rDNA is organized as tandem repeat units of two types: a major fraction of 20-25 kb (14-17 . 10(6) daltons) and a minor one 15-16 kb (10-11 . 10(6) daltons). The heterogeneous length of the repeat units was predetermined by the heterogeneity of nontranscribed spacers.

摘要

对硬骨鱼泥鳅（Misgurnus fossilis L.）基因组中核糖体基因的组织以及扩增的核仁进行了研究。通过密度梯度离心分离核糖体DNA（rDNA），用EcoRI内切酶消化并用18S和28S rRNA进行定位。通过电子显微镜可视化技术研究了卵母细胞核仁中核糖体基因的转录单位。泥鳅rDNA的重复单位被EcoRI切割成两个片段：一个恒定片段（3×10⁶道尔顿）和一个异质片段（主要类型为11 - 13×10⁶道尔顿，次要类型为7 - 8×10⁶道尔顿）。发现转录单位的平均大小为2.5±0.2微米。非转录间隔区的长度在2.4至2.9微米之间变化；然而，也注意到有1.2 - 1.4微米的较短间隔区。数据表明泥鳅rDNA被组织成两种类型的串联重复单位：主要部分为20 - 25 kb（14 - 17×10⁶道尔顿），次要部分为15 - 16 kb（10 - 11×10⁶道尔顿）。重复单位长度的异质性由非转录间隔区的异质性预先决定。