title: Analysis of plasmid DNA synthesis by double tracer method--differential effects of rifampicin and chloramphenicol on the replication of pSC101 and ColEl-amp in Escherichia coli K-12.
abstract: An Escherichia coli strain, CR34 , harboring both pSC101 and ColEl -amp plasmids was exposed to media containing rifampicin (100 micrograms/ml) and/or chloramphenicol (180 micrograms/ml) and the cells were labeled for 20 min with 3H-thymine at 3, 25 and 50 min after exposure to drug(s). The plasmid DNA synthesis was assayed by DNA-DNA hybridization with 14C-labeled pSC 134 DNA as internal marker. In the presence of rifampicin, the replication of pSC 101 was from 57 to 104% that in its absence, and that of ColEl -amp was from 17 to 26%. The DNA replication of pSC 101 after addition of chloramphenicol was reduced to 35 to 75%, and that of ColEl -amp was reduced to 39% and then restored to 92%. This restoration was not observed in the presence of rifampicin.
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis; D002250:Carbon Radioisotopes; D002701:Chloramphenicol / Q000494:pharmacology*; D004261:DNA Replication / Q000187:drug effects*; D004269:DNA, Bacterial / Q000096:biosynthesis*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D006824:Hybridization, Genetic; D007553:Isotope Labeling; D010957:Plasmids; D012313:RNA / Q000096:biosynthesis; D012293:Rifampin / Q000494:pharmacology*; D014316:Tritium
chemical_list: D001426:Bacterial Proteins; D002250:Carbon Radioisotopes; D004269:DNA, Bacterial; D014316:Tritium; D012313:RNA; D002701:Chloramphenicol; D012293:Rifampin