Zhukova Alina, Zakharov Gennadii, Pavlova Olga, Saifitdinova Alsu
Herzen State Pedagogical University of Russia, Saint Petersburg, Russia Herzen State Pedagogical University of Russia Saint Petersburg Russia.
Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia Pavlov Institute of Physiology, Russian Academy of Sciences Saint Petersburg Russia.
Comp Cytogenet. 2024 Sep 25;18:183-198. doi: 10.3897/compcytogen.18.127373. eCollection 2024.
Ribosomal RNA (18S, 5.8S, 28S) gene clusters in genomes form regions that consist of multiple tandem repeats. They are located on a single or several pairs of chromosomes and play an important role in the formation of the nucleolus responsible for the assembly of ribosome subunits. The rRNA gene cluster sequences are widely used for taxonomic studies, however at present, complete information on the avian rDNA repeat unit structure including intergenic spacer sequence is available only for the chicken ( Linnaeus, 1758). The GC enrichment and high-order repeats peculiarities within the intergenic spacer described for the chicken rDNA cluster may be responsible for these failures. The karyotype of the Japanese quail ( Temminck et Schlegel, 1849) deserves close attention because, unlike most birds, it has three pairs of nucleolar organizer bearing chromosomes, two of which are microchromosomes enriched in repeating elements and heterochromatin that carry translocated terminal nucleolar organizers. Here we assembled and annotated the complete Japanese quail ribosomal gene cluster sequence of 21166 base pairs (GenBank under the registration tag BankIt2509210 CoturnixOK523374). This is the second deciphered avian rDNA cluster after the chicken. Despite the revealed high similarity with the chicken corresponding sequence, it has a number of specific features, which include a slightly lower degree of GC content and the presence of bendable elements in the content of both the transcribed spacer I and the non-transcribed intergenic spacer.
基因组中的核糖体RNA（18S、5.8S、28S）基因簇形成由多个串联重复组成的区域。它们位于一对或几对染色体上，在负责核糖体亚基组装的核仁形成中起重要作用。rRNA基因簇序列广泛用于分类学研究，然而目前，仅鸡（Linnaeus，1758）拥有关于包括基因间隔序列在内的鸟类rDNA重复单元结构的完整信息。鸡rDNA簇基因间隔区内描述的GC富集和高阶重复特性可能是导致这些研究失败的原因。日本鹌鹑（Temminck et Schlegel，1849）的核型值得密切关注，因为与大多数鸟类不同，它有三对带有核仁组织区的染色体，其中两对是富含重复元件和异染色质的微染色体，携带易位的末端核仁组织区。在这里，我们组装并注释了21166个碱基对的完整日本鹌鹑核糖体基因簇序列（GenBank登录号为BankIt2509210 CoturnixOK523374）。这是继鸡之后第二个被破译的鸟类rDNA簇。尽管与鸡的相应序列有很高的相似性，但它有许多特定特征，包括GC含量略低，以及转录间隔区I和非转录基因间隔区都存在可弯曲元件。
