Gravholt C H, Friedrich U, Caprani M, Jørgensen A L
Cytogenetic Laboratory, Psychiatric Hospital, Aarhus, Risskov, Denmark.
Genomics. 1992 Dec;14(4):924-30. doi: 10.1016/s0888-7543(05)80113-2.
We characterized 21 t(13;14) and 3 t(14;21) Robertsonian translocations for the presence of DNA derived from the short arms of the translocated acrocentric chromosomes and identified their centromeres. Nineteen of these 24 translocation carriers were unrelated. Using centromeric alpha-repeat DNA as chromosome-specific probe, we found by in situ hybridization that all 24 translocation chromosomes were dicentric. The chromatin between the two centomeres did not stain with silver, and no hybridization signal was detected with probes for rDNA or beta-satellite DNA that flank the distal and proximal ends of the rDNA region on the short arm of the acrocentrics. By contrast, all 24 translocation chromosomes gave a distinct hybridization signal when satellite III DNA was used as probe. This result strongly suggests that the chromosomal rearrangements leading to Robertsonian translocations occur preferentially in satellite III DNA. We hypothesize that guanine-rich satellite III repeats may promote chromosomal recombination by formation of tetraplex structures. The findings localize satellite III DNA to the short arm of the acrocentric chromosomes distal to centromeric alpha-repeat DNA and proximal to beta-satellite DNA.
我们对21例t(13;14)和3例t(14;21)罗伯逊易位进行了特征分析，以确定是否存在源自易位近端着丝粒染色体短臂的DNA，并鉴定它们的着丝粒。这24例易位携带者中有19例无亲缘关系。使用着丝粒α-重复DNA作为染色体特异性探针，我们通过原位杂交发现所有24条易位染色体都是双着丝粒的。两个着丝粒之间的染色质不着银，用针对近端着丝粒染色体短臂上rDNA区域远端和近端侧翼的rDNA或β-卫星DNA探针未检测到杂交信号。相比之下，当使用卫星III DNA作为探针时，所有24条易位染色体都给出了明显的杂交信号。这一结果强烈表明，导致罗伯逊易位的染色体重排优先发生在卫星III DNA中。我们推测富含鸟嘌呤的卫星III重复序列可能通过形成四链体结构促进染色体重组。这些发现将卫星III DNA定位在近端着丝粒染色体短臂上，位于着丝粒α-重复DNA的远端和β-卫星DNA的近端。
