Barbosa Patrícia, de Oliveira Luiz Antonio, Pucci Marcela Baer, Santos Mateus Henrique, Moreira-Filho Orlando, Vicari Marcelo Ricardo, Nogaroto Viviane, de Almeida Mara Cristina, Artoni Roberto Ferreira
Programa de Pós Graduação em Biologia Evolutiva, Departamento de Biologia Estrutural, Molecular e Genética, Universidade Estadual de Ponta Grossa, Avenida Carlos Cavalcanti 4748, Ponta Grossa, PR, 84030-900, Brazil.
Genetica. 2015 Feb;143(1):55-62. doi: 10.1007/s10709-014-9813-2. Epub 2014 Dec 31.
Most part of the eukaryotic genome is composed of repeated sequences or multiple copies of DNA, which were considered as "junk DNA", and may be associated to the heterochromatin. In this study, three populations of Astyanax aff. scabripinnis from Brazilian rivers of Guaratinguetá and Pindamonhangaba (São Paulo) and a population from Maringá (Paraná) were analyzed concerning the localization of the nucleolar organizer regions (Ag-NORs), the As51 satellite DNA, the 18S ribosomal DNA (rDNA), and the 5S rDNA. Repeated sequences were also isolated and identified by the Cot - 1 method, which indicated similarity (90%) with the LINE UnaL2 retrotransposon. The fluorescence in situ hybridization (FISH) showed the retrotransposon dispersed and more concentrated markers in centromeric and telomeric chromosomal regions. These sequences were co-localized and interspaced with 18S and 5S rDNA and As51, confirmed by fiber-FISH essay. The B chromosome found in these populations pointed to a conspicuous hybridization with LINE probe, which is also co-located in As51 sequences. The NORs were active at unique sites of a homologous pair in the three populations. There were no evidences that transposable elements and repetitive DNA had influence in the transcriptional regulation of ribosomal genes in our analyses.
真核生物基因组的大部分由重复序列或DNA的多个拷贝组成，这些曾被视为“垃圾DNA”，可能与异染色质有关。在本研究中，分析了来自巴西瓜拉廷格塔河和皮达蒙汉加巴河（圣保罗）的三个拟糙鳞脂鲤种群以及来自马林加（巴拉那）的一个种群的核仁组织区（Ag-NORs）、As51卫星DNA、18S核糖体DNA（rDNA）和5S rDNA的定位。还通过Cot-1方法分离和鉴定了重复序列，结果表明其与LINE UnaL2逆转座子具有相似性（90%）。荧光原位杂交（FISH）显示逆转座子在着丝粒和端粒染色体区域分散且标记更为集中。通过纤维-FISH分析证实，这些序列与18S和5S rDNA以及As51共定位且相互间隔。在这些种群中发现的B染色体显示与LINE探针有明显杂交，该探针也与As51序列共定位。在这三个种群中，NORs在同源对的独特位点处具有活性。在我们的分析中，没有证据表明转座元件和重复DNA对核糖体基因的转录调控有影响。
