title: Cell cycle arrest of heat-inactivated ts 2 BALB/c-3T3 mouse fibroblasts, temperature-sensitive for DNA synthesis.
abstract: The ts 2 derivative of BALB/c-3T3 mouse fibroblasts is a cell division cycle (cdc) mutant. Upon expression of the heat-sensitive defect, ts 2 cells arrest late in G1 at, or very near the G1/S traverse. This conclusion derives from three kinds of experiment. In the first the cells were brought to different stages of the cell cycle by physiological manipulation, or with specific anti-metabolites. They were then released from the resulting blocks, and their subsequent cell-cycle progression, at the permissive- and non-permissive temperature (npt), was followed. The second experiment was an execution point analysis. In the third, premature chromosome condensation was performed between metaphase HeLa cells and temperature-blocked ts 2 cells. The resulting prematurely-condensed chromosomes were largely of the morphotype of very late G1 cells. The ts 2 cells are prevented from expressing their defect by temporary incubation at 38.5 degrees C in the G0, non-cycling state and by prior arrest in early S phase, imposed by hydroxyurea treatment. Such prevention is not allowed ts 2 cells incubated at the npt in the absence of isoleucine, a procedure which brings cells to mid-G1 arrest.
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division; D002460:Cell Line; D002875:Chromosomes / Q000648:ultrastructure; D004261:DNA Replication; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D006358:Hot Temperature; D006918:Hydroxyurea / Q000494:pharmacology; D007532:Isoleucine / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C / Q000235:genetics; D014176:Protein Biosynthesis; D011506:Proteins / Q000502:physiology
chemical_list: D011506:Proteins; D007532:Isoleucine; D006918:Hydroxyurea