Replication of chromosomal DNA in cultured abnormal human cells.
The replication of chromosomal DNA in a series of abnormal human cell cultures has been studied by means of DNA-fiber autoradiography. In lymphocytes with trisomy 21, in fibroblasts of 45,X;47,XXX;49,XXXXY; and 49,XXXXX chromosomal constitution, and in fibroblasts from a patient with xeroderma pigmentosum (De Sanctis-Cacchione syndrome), the rate of DNA replication does not differ from that in normal cells, varying in a single fork from 0.2 to 1.0 micrometer/min with a mean of about 0.6 micrometer/min. In fibroblasts with trisomy 7 the rate of DNA replication is greater, varying from 0.3 to 1.2 micrometer/min with a mean of about 0.8 micrometer/min. The sizes of replication units in all cells examined are from 80 to 500 micrometer with a mean of about 200-300 micrometer.
D001345:Autoradiography; D002478:Cells, Cultured; D004261:DNA Replication; D004314:Down Syndrome / Q000235:genetics*; D005347:Fibroblasts / Q000648:ultrastructure; D006801:Humans; D008214:Lymphocytes / Q000648:ultrastructure; D012729:Sex Chromosome Aberrations; D014983:Xeroderma Pigmentosum / Q000235:genetics*