Constitutive heterochromatin, consisting of repetitive sequences, diverges very rapidly; therefore, its nucleotide sequences and chromosomal distributions are often largely different, even between closely related species. The chromosome C-banding patterns of two Gerbillinae species, Meriones unguiculatus and Gerbillus perpallidus, vary greatly, even though they belong to the same subfamily. To understand the evolution of C-positive heterochromatin in these species, we isolated highly repetitive sequences, determined their nucleotide sequences, and characterized them using chromosomal and filter hybridization. We obtained a centromeric repeat (MUN-HaeIII) and a chromosome 13-specific repeat (MUN-EcoRI) from M. unguiculatus. We also isolated a centromeric/pericentromeric repeat (GPE-MBD) and an interspersed-type repeat that was predominantly amplified in the X and Y chromosomes (GPE-EcoRI) from G. perpallidus. GPE-MBD was found to contain a 17-bp motif that is essential for binding to the centromere-associated protein CENP-B. This indicates that it may play a role in the formation of a specified structure and/or function of centromeres. The nucleotide sequences of the three sequence families, except GPE-EcoRI, were conserved only in Gerbillinae. GPE-EcoRI was derived from the long interspersed nuclear elements 1 retrotransposon and showed sequence homology throughout Muridae and Cricetidae species, indicating that the repeat sequence occurred at least in the common ancestor of Muridae and Cricetidae. Due to a lack of assembly data of highly repetitive sequences constituting heterochromatin in whole-genome sequences of vertebrate species published to date, the knowledge obtained in this study provides useful information for a deep understanding of the evolution of repetitive sequences in not only rodents but also in mammals.

中文翻译：

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构成两个沙鼠物种染色体位点特异性异染色质的高度重复 DNA 序列的多样性和进化。

组成型异染色质由重复序列组成，分化非常快；因此，即使在密切相关的物种之间，其核苷酸序列和染色体分布也常常有很大不同。两种沙鼠亚科物种（Meriones unguiculatus 和 Gerbillus perpallidus）的染色体 C 带模式差异很大，即使它们属于同一亚科。为了了解这些物种中 C 阳性异染色质的进化，我们分离了高度重复的序列，确定了它们的核苷酸序列，并使用染色体和过滤杂交对其进行了表征。我们从 M. unguiculatus 中获得了一个着丝粒重复序列 (MUN-HaeIII) 和一个 13 号染色体特异性重复序列 (MUN-EcoRI)。我们还从 G. perpallidus 中分离出了着丝粒/近着丝粒重复序列 (GPE-MBD) 和主要在 X 和 Y 染色体中扩增的散在型重复序列 (GPE-EcoRI)。研究发现 GPE-MBD 含有一个 17 bp 基序，该基序对于结合着丝粒相关蛋白 CENP-B 至关重要。这表明它可能在着丝粒特定结构和/或功能的形成中发挥作用。除GPE-EcoRI外，这三个序列家族的核苷酸序列仅在沙鼠亚科中保守。GPE-EcoRI源自长散布核元件1反转录转座子，并且在整个鼠科和仓鼠科物种中显示出序列同源性，表明重复序列至少出现在鼠科和仓鼠科的共同祖先中。由于迄今为止发表的脊椎动物全基因组序列中缺乏组成异染色质的高度重复序列的组装数据，本研究获得的知识为深入了解啮齿类动物和动物中重复序列的进化提供了有用的信息。在哺乳动物中。