title: DNA chain elongation rates in marrow cells from vitamin B12-deficient patients and methotrexate-treated mice.
abstract: The DNA synthesized by marrow cells from patients with vitamin B12 deficiency and mice previously given methotrexate (MTX), has been investigated. Suspensions of bone marrow cells were pulse-labelled with [methyl-3H]thymidine or deoxy [5-3H]cytidine for 30 s and the radioactivity in the DNA was chased thereafter in the presence of 10 microM non-radioactive nucleoside for periods up to 60 min. The rates of elongation of new daughter strands were then assessed by hydroxyapatite chromatography of alkali-denatured DNA samples. No significant differences were found between the average rates of elongation of daughter strands from control marrow cells on the one hand and the vitamin B12-deficient or the methotrexate-affected cells on the other. This is to be contrasted with the results of previous studies which have shown a retardation in the rates of movement of replication forks in stimulated, cultured lymphocytes obtained from vitamin B12- or folate-deficient patients.
mesh_terms: D000749:Anemia, Megaloblastic / Q000378:metabolism; D000818:Animals; D001853:Bone Marrow / Q000187:drug effects / Q000378:metabolism*; D002845:Chromatography; D004247:DNA / Q000096:biosynthesis*; D017886:Durapatite; D005260:Female; D006801:Humans; D006882:Hydroxyapatites; D006918:Hydroxyurea / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D008727:Methotrexate / Q000633:toxicity*; D051379:Mice; D008807:Mice, Inbred BALB C; D014806:Vitamin B 12 Deficiency / Q000378:metabolism*
chemical_list: D006882:Hydroxyapatites; D004247:DNA; D017886:Durapatite; D006918:Hydroxyurea; D008727:Methotrexate