BACKGROUND & AIMS:
:Segmental duplication is a major structural variation that occurs in chromosomes. Duplication leads to the production of gene copies with increased numbers of related repeat segments, causing the global genome to be in a state of imbalance. In addition, if the added segment contains a centromeric specific DNA, the duplicated chromosome will have structural multiple centromeres. We identified a segmental duplication containing structurally tricentric regions derived from the short arm of chromosome 11 (11L∙ + 11L∙ + 11S∙11S∙11S∙11S, "∙" represents the centromeric DNA repeat loci), and analyzed its implications for cell division and genome-wide expression. In the variant, only the middle centromere of 11S∙11S∙11S∙11S is functionally active. As a result, the structurally tricentric chromosome was stable in mitosis, because it is actually a functional monocentric chromosome. However, the structurally tricentric chromosome, which usually formed a bivalent, was either arranged on the equatorial plane or was lagging, which affected its separation during meiosis. Furthermore, RNA-seq and RT-qPCR analysis showed that the segmental duplication affected genome-wide expression patterns. 34.60% of genes in repeat region showed positive dosage effect. Thus, the genes on chromosome arm 11S-2 didn't exhibit obviously dosage compensation, as illustrated by no peak around a ratio of 1.00. However, the gene dosage effect will reduce after sexual reproduction of a generation.
背景与目标:
:节段重复是发生在染色体上的主要结构变异。复制导致产生具有相关重复片段数量增加的基因拷贝,从而导致全球基因组处于失衡状态。另外,如果添加的片段包含着丝粒特异性DNA,则复制的染色体将具有多个结构着丝粒。我们鉴定出一个片段重复,该片段包含源自11号染色体短臂的结构性三中心区域(11L∙11L∙11S∙11S∙11S∙11S,“∙”代表着丝粒DNA重复基因座),并分析了其对细胞分裂和基因组的影响范围内的表达式。在变体中,只有11S∙11S∙11S∙11S的中间着丝粒起作用。结果,结构上的三中心染色体在有丝分裂中是稳定的,因为它实际上是功能性的单中心染色体。但是,通常形成二价的结构性三中心染色体要么排列在赤道平面上,要么滞后,影响了减数分裂过程中的分离。此外,RNA-seq和RT-qPCR分析表明,节段重复会影响全基因组表达模式。重复区域中34.60%的基因显示出积极的剂量效应。因此,第11S-2号染色体上的基因没有明显的剂量补偿,如1.00左右的峰没有显示。但是,一代有性繁殖后,基因剂量效应将降低。