ABSTRACT
A study of the late DNA replication pattern in chromosomes of human acute leucaemia cells revealed a significant diffrence from control. Chromosomes, 2,3 and 4-5 of the acute leucaemia cells finish their DNA replication earlier, and chromosomes 1, 13-15 and 16 later, compared to the control chromosomes. The difference in the pattern of DNA replication between analogous chromosomes of acute leucaemia and donor cells was associated with the discovery of large late-replicating chromatin blocks in the pericentromeric regions of leucaemia cell chromosomes. Some relationship is suggested between the pattern of pericentromeric heterochromatin DNA replication and cell differentiation.
Subject(s)
Bone Marrow Cells , Bone Marrow/pathology , Chromosomes, Human, 1-3/metabolism , Chromosomes, Human, 13-15/metabolism , Chromosomes, Human, 16-18/metabolism , Chromosomes, Human, 4-5/metabolism , DNA Replication , DNA, Neoplasm/biosynthesis , Leukemia/genetics , Acute Disease , Autoradiography , Cell Differentiation , Humans , Leukemia/pathology , Thymidine , TritiumABSTRACT
Human metaphase chromosomes A1 and A3 did bind more tritiated poly-L-lysine ([3H]PL) when they were isolated from lymphocyte cultures treated with LiCl rather than with NaCl or KCl. A2 chromosome did not show this differential behavior and in all three cases did bind more [3H]PL than the control A2 chromosome. The effect was dependent on the time of exposure of cells to the salts in tissue culture and on the degree of chromosomal contraction. The observed differences in [3H]PL binding are probably due to differences in surface morphology of the three chromosomes caused by treatment with alkali metal salts.
