The eukaryote genome is enriched by different types of repetitive DNA sequences and is most abundant in heterochromatin regions. Historically, no function has been assigned to these sequences, which makes them the target of studies that have demonstrated their structural and functional importance in the genome. Despite having a constant chromosome number, the genus Melipona has species with wide variation in heterochromatin content, from 8 to 73%, which is an important feature to be investigated regarding its origin and evolution. In the present study, a repetitive DNA sequence of Melipona mondury was isolated by restriction enzyme digestion. This sequence was used to hybridize chromosomes of eight Melipona species that include representatives of the four subgenera and present divergent characteristics in relation to the heterochromatin content. Considering that rDNA localization has shown differences in Melipona , 16 species of this genus were analyzed with 18S rDNA probe. Our data suggest that heterochromatin growth occurred independently in the Michmelia and Melikerria subgenera, considering that the isolated repetitive DNA sequence was shared only by the Michmelia species. Amplification possibly occurred from the centromeric region, causing the displacement of the rDNA sites to the ends of the chromosomes. The repetitive DNA sequence used is a constituent of Michmelia heterochromatin, which that arose from the common ancestor of the species of this subgenus.

中文翻译：

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重复序列研究中的分子细胞遗传学有助于了解 Melipona（膜翅目、Meliponini）中异染色质的进化

真核生物基因组富含不同类型的重复 DNA 序列，在异染色质区域最为丰富。从历史上看，这些序列没有被赋予任何功能，这使它们成为证明它们在基因组中结构和功能重要性的研究的目标。尽管具有恒定的染色体数量，但 Melipona 属的异染色质含量差异很大，从 8% 到 73%，这是关于其起源和进化的一个重要特征。在本研究中，Melipona mondury 的重复 DNA 序列是通过限制性内切酶消化分离的。该序列用于杂交八个 Melipona 物种的染色体，这些物种包括四个亚属的代表，并在异染色质含量方面表现出不同的特征。考虑到 rDNA 定位在 Melipona 中显示出差异，用 18S rDNA 探针分析了该属的 16 种。我们的数据表明异染色质生长在 Michmelia 和 Melikerria 亚属中独立发生，考虑到分离的重复 DNA 序列仅由 Michmelia 物种共享。扩增可能发生在着丝粒区域，导致 rDNA 位点位移到染色体末端。使用的重复 DNA 序列是 Michmelia 异染色质的一个组成部分，它来自该亚属物种的共同祖先。我们的数据表明异染色质生长在 Michmelia 和 Melikerria 亚属中独立发生，考虑到分离的重复 DNA 序列仅由 Michmelia 物种共享。扩增可能发生在着丝粒区域，导致 rDNA 位点位移到染色体末端。使用的重复 DNA 序列是 Michmelia 异染色质的一个组成部分，它来自该亚属物种的共同祖先。我们的数据表明异染色质生长在 Michmelia 和 Melikerria 亚属中独立发生，考虑到分离的重复 DNA 序列仅由 Michmelia 物种共享。扩增可能发生在着丝粒区域，导致 rDNA 位点位移到染色体末端。使用的重复 DNA 序列是 Michmelia 异染色质的一个组成部分，它来自该亚属物种的共同祖先。