Department of Genetics and Biotechnology (DGB), CAG - Laboratory of Cytogenomics and Animal Genomics, University of Trás-os-Montes e Alto Douro, Vila Real, Portugal.
BioISI - Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal.
Chromosome Res. 2021 Dec;29(3-4):301-312. doi: 10.1007/s10577-021-09667-0. Epub 2021 Jul 31.
The interest in Robertsonian fusion chromosomes (Rb fusions), sometimes referred to as Robertsonian translocations, derives from their impact on mammalian karyotype evolution, as well from their influence on fertility and disease. The formation of a Rb chromosome necessitates the occurrence of double strand breaks in the pericentromeric regions of two chromosomes in the satellite DNA (satDNA) sequences. Here, we report on the fine-scale molecular analysis of the centromeric satDNA families in the Rb(1;29) translocation of domestic cattle and six antelope species of the subfamily Bovinae. We do so from two perspectives: its occurrence as a chromosomal abnormality in cattle and, secondly, as a fixed evolutionarily rearrangement in spiral-horned antelope (Tragelaphini). By analysing the reorganization of satDNAs in the centromeric regions of translocated chromosomes, we show that Rb fusions are multistep, complex rearrangements which entail the precise elimination and reorganization of specific (peri)centromeric satDNA sequences. Importantly, these structural changes do not influence the centromeric activity of the satellite DNAs that provide segregation stability to the translocated chromosome. Our results suggest a common mechanism for Rb fusions in these bovids and, more widely, for mammals in general.
罗伯逊易位（Robertsonian fusion chromosomes，Rb fusions），也被称为罗伯逊易位，因其对哺乳动物核型进化的影响，以及对生育能力和疾病的影响而受到关注。形成 Rb 染色体需要两条染色体在卫星 DNA（satDNA）序列的着丝粒区域发生双链断裂。在这里，我们报告了家牛的 Rb(1;29)易位和牛科亚科的六种羚羊物种的着丝粒 satDNA 家族的精细分子分析。我们从两个角度进行了分析：一是在牛中作为染色体异常的发生，二是作为螺旋角羚羊（Tragelaphini）中固定的进化重排。通过分析易位染色体着丝粒区域 satDNAs 的重组，我们表明 Rb 融合是多步骤、复杂的重排，需要精确地消除和重组特定的（peri）着丝粒 satDNA 序列。重要的是，这些结构变化不会影响为易位染色体提供分离稳定性的卫星 DNA 的着丝粒活性。我们的结果表明，这些牛科动物中存在罗伯逊易位的共同机制，更广泛地说，在哺乳动物中也存在这种机制。
