title: Effect of ultraviolet light on division and deoxyribonucleic acid synthesis in Haemophilus influenzae.
abstract: The effects of ultraviolet (UV) light on cell morphology, deoxyribonucleic acid (DNA) synthesis, and protein synthesis in UV-sensitive and UV-resistant strains of Haemophilus influenzae were examined. Relatively low doses of UV induce lyses in the sensitive strains but not in the resistant mutant; however, UV temporarily blocks cell division of the resistant mutant, and elongated cells are formed after a period of incubation. Low doses of UV do not stop DNA synthesis in any of the strains examined; however, they do slow the rate of DNA synthesis in a manner consistent with the model correlating the kinetics of postirradiation DNA synthesis with the cell's ability to repair UV-induced DNA lesions. The data are not consistent with a model in which UV causes all DNA synthesis to stop for a time linearly dependent on dose.
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis; D002247:Carbon Isotopes; D002455:Cell Division / Q000528:radiation effects*; D003124:Colorimetry; D003470:Culture Media; D004269:DNA, Bacterial / Q000096:biosynthesis* / Q000528:radiation effects; D005827:Genetics, Microbial; D006193:Haemophilus influenzae / Q000166:cytology* / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D008858:Microscopy, Phase-Contrast; D009154:Mutation; D011830:Radiation Effects; D013053:Spectrophotometry; D013936:Thymidine / Q000378:metabolism; D014316:Tritium; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D002247:Carbon Isotopes; D003470:Culture Media; D004269:DNA, Bacterial; D014316:Tritium; D013936:Thymidine