Isolation of UV‐sensitive clones from mouse cell lines by lederberg style replica plating

Abstract

Seven UV-sensitive clones were isolated from the mouse cell lines, FM3A and L5178Y, using Lederberg style replica plating. The UV-sensitive clones were found at a frequency of 1 in 886 clones of FM3A and of 6 in 420 clones of L5178Y, after treatment with N-methyl-N'-nitro-N-nitrosoguanidine, but no UV-sensitive clones were obtained in the untreated controls. The Do values of freshly isolated clones were 1 0 to 2 1 ergs/mmZ (mainly 10 to 13 ergs/ mmz), while the original FM3A and L5178Y lines had Do values of 32 ergs/mm2. The UV-sensitive clones were found to be rather stable for a period ranging from two to eight months after isolation. However, later some of them tended to lose their UV-sensitivity, in terms of increase in Do values or n values. More stable UV-sensitive subclones could be isolated from these populations by cloning using the replica plating method. Caffeine was found to potentiate the lethal action of UV-irradiation on the UV-sensitive clones as well as on the original FM3A cells.

Some Aspects of Eukaryotic DNA Replication

“…Thus, in those cells that appear to be dnals (tsA1S9 and Is Cl), histone synthesis is tightly coupled to DNA synthesis (4 15; Sheinin and Lewis, unpublished observations). In contrast, in hamster CH-K12 cells, which are Is in a Gt phase function required for subsequent initiation of S phase (383)(384)(385)(386)(387)(388)(389)(390)(391)(392), histone biosynthesis continues at 60% of control levels after DNA synthesis has been inactivated to 14% of control levels (387). Also these cells exhibit other modifi cations in protein synthesis, in particular greatly enhanced synthesis of a cytoplasmic protein not yet identified.…”

Large-scale isolation of UV-sensitive clones of CHO cells

“…Replica plating is the least harsh of these techniques and may permit the recovery of cell lines highly sensitive to W or other mutagens. Kuroki and Miyashita [27] The method used in our experiment was designed to include effective induction and selection procedures. Since we were able t o isolate 20 mutants out of 72 surviving clones, the method appears to function as we originally expected.…”

Postirradiation Properties of a Uv‐sensitive Variant of Cho

“…These include cells from the human cancer-prone genetic disease, xeroderma pigmentosum, many of which are deficient in excision repair (Cleaver, 1970(Cleaver, , 1980Bootsma, 1979). The recent isolation of a number of DNA repair-deficient and radiation-sensitive hamster and mouse cell lines has introduced the possibility of studying DNA damage, repair, replication and mutagenesis in these systems (Thompson et a/., 1980(Thompson et a/., , 1981Stamato and Waldren, 1977;Busch et a!., 1980;Adair, 1980;Kuroki and Miyashita, 1977;Sato and Hieda, 1979; Schultz et a/., 1981).…”