通过短臂相连的X染色体：无活性着丝粒的存在影响复制模式。

X chromosomes attached by their short arm : presence of an inactive centromere influences the replication patterns.

作者信息

Maraschio P, Simoni G, Terzoli G L, d'Alberton A, Crosignani P G

出版信息

Ann Genet. 1980;23(4):208-12.

Abstract

A 19 years old girl with gonadal dysgenesis and short stature had one giant chromosome formed by two X-chromosomes attached by their short arms 46,X,i dic(X) (p223::p223) A 45,X cell line was present in 40% of cultured lymphocytes but only in 2% of fibroblasts cultured from the right gonad and absent in fibroblasts from the left gonad and skin. The abnormal chromosome had one Cd-positive, active centromere and one inactive centromere. A study of DNA replication with autoradiography and BrdU treatment revealed that the abnormal X was always the late replicating one. In a proportion of cells there was an asymmetric pattern of replication : the region with the inactive centromere had a tendency to replicate later than the portion with the functioning centromere. The Xg blood group segregation suggested that the attached X chromosomes were of paternal origin and therefore a true isodicentric formed after an isochromatid break followed by joining of the two sister chromatids.

摘要

一名19岁患有性腺发育不全和身材矮小的女孩，有一条由两条通过短臂相连的X染色体形成的巨大染色体，核型为46,X,i dic(X) (p223::p223)。在40%的培养淋巴细胞中存在45,X细胞系，但在取自右侧性腺的成纤维细胞中仅占2%，而在左侧性腺和皮肤的成纤维细胞中不存在。异常染色体有一个Cd阳性的活性着丝粒和一个无活性着丝粒。用放射自显影术和BrdU处理进行DNA复制研究表明，异常的X染色体总是晚复制的那条。在一部分细胞中存在不对称的复制模式：无活性着丝粒区域比有功能着丝粒的部分倾向于更晚复制。Xg血型分离表明，相连的X染色体来自父方，因此是在等染色单体断裂后两条姐妹染色单体连接形成的真正等臂双着丝粒染色体。