Carvalho Natalia D M, Pinheiro Vanessa S S, Carmo Edson J, Goll Leonardo G, Schneider Carlos H, Gross Maria C
Laboratx00F3;rio de Citogenx00F4;mica Animal, Instituto de Cix00EA;ncias Biolx00F3;gicas, Universidade Federal do Amazonas, Manaus, Brazil.
Cytogenet Genome Res. 2015;147(2-3):161-8. doi: 10.1159/000443714. Epub 2016 Feb 12.
Repetitive DNA is the largest fraction of the eukaryote genome and comprises tandem and dispersed sequences. It presents variations in relation to its composition, number of copies, distribution, dynamics, and genome organization, and participates in the evolutionary diversification of different vertebrate species. Repetitive sequences are usually located in the heterochromatin of centromeric and telomeric regions of chromosomes, contributing to chromosomal structures. Therefore, the aim of this study was to physically map repetitive DNA sequences (5S rDNA, telomeric sequences, tropomyosin gene 1, and retroelements Rex1 and SINE) of mitotic chromosomes of Amazonian species of teiids (Ameiva ameiva, Cnemidophorus sp. 1, Kentropyx calcarata, Kentropyx pelviceps, and Tupinambis teguixin) to understand their genome organization and karyotype evolution. The mapping of repetitive sequences revealed a distinct pattern in Cnemidophorus sp. 1, whereas the other species showed all sequences interspersed in the heterochromatic region. Physical mapping of the tropomyosin 1 gene was performed for the first time in lizards and showed that in addition to being functional, this gene has a structural function similar to the mapped repetitive elements as it is located preferentially in centromeric regions and termini of chromosomes.
重复DNA是真核生物基因组中最大的部分，由串联和分散序列组成。它在组成、拷贝数、分布、动态变化和基因组组织方面存在差异，并参与不同脊椎动物物种的进化多样化。重复序列通常位于染色体着丝粒和端粒区域的异染色质中，对染色体结构有贡献。因此，本研究的目的是对亚马逊鞭尾蜥科物种（双线丽脂鲤、某种强棱蜥、饰纹角蜥、巴西角蜥和阿根廷黑白泰加蜥）有丝分裂染色体的重复DNA序列（5S rDNA、端粒序列、原肌球蛋白基因1以及反转录元件Rex1和短散在核元件）进行物理图谱绘制，以了解它们的基因组组织和核型进化。重复序列的图谱绘制揭示了某种强棱蜥的独特模式，而其他物种的所有序列都散布在异染色质区域。首次在蜥蜴中对原肌球蛋白1基因进行了物理图谱绘制，结果表明，该基因除了具有功能外，还具有与已绘制图谱的重复元件类似的结构功能，因为它优先位于染色体的着丝粒区域和末端。
