RESUMO
Analyses of the time of recombination in bacteria infected with phage lambda and in spheroplasts infected with purified phage lambda DNA indicate a preponderance of recombination occurring before replication ("early recombination") after infection with tandem dimers formed in vitro compared to linear monomer DNA and phage infections. Among the early recombinants is a large fraction of cells that produces one recombinant type exclusively. Two suggestions are discussed-that a dimer-like molecule is the precursor of the recombinant progeny molecule and that one recombinant chromosome is the frequent or exclusive product of a recombinational event.
Assuntos
Colífagos/metabolismo , Replicação do DNA , Recombinação Genética , Replicação Viral , Centrifugação com Gradiente de Concentração , Colífagos/análise , DNA Viral/análise , Escherichia coli/metabolismo , Lisogenia , Peso Molecular , Esferoplastos , Timidina/metabolismo , TrítioAssuntos
Colífagos , DNA Viral/farmacologia , Escherichia coli , Glicóis , Formas L , Transformação Genética , Técnicas Bacteriológicas , Centrifugação com Gradiente de Concentração , Césio , Cloretos , Colífagos/isolamento & purificação , Meios de Cultura , DNA Bacteriano , DNA Viral/isolamento & purificação , Ácido Edético , Muramidase , Polietilenos , Protaminas , Esferoplastos/crescimento & desenvolvimento , SacaroseRESUMO
After irradiation, nearly equal amounts of deoxyribonucleic acid (DNA) are synthesized in radiation-sensitive Salmonella typhimurium and in resistant Escherichia coli B/r. However, the DNA synthesized in S. typhimurium is of low molecular weight, whereas that made in the E. coli B/r is like that synthesized in the unirradiated controls.
Assuntos
DNA Bacteriano/análise , Escherichia coli/efeitos da radiação , Efeitos da Radiação , Salmonella typhimurium/efeitos da radiação , Centrifugação com Gradiente de Concentração , Meios de Cultura , Replicação do DNA , DNA Bacteriano/biossíntese , Escherichia coli/análise , Escherichia coli/metabolismo , Genética Microbiana , Peso Molecular , Radiogenética , Salmonella typhimurium/análise , Salmonella typhimurium/metabolismo , Sacarose , Moldes Genéticos , Timidina/metabolismo , TrítioRESUMO
Salmonella typhimurium LT-2 was compared with radioresistant (B/r) and radiosensitive (B(s-2)) strains of Escherichia coli in respect to the survival, deoxyribonucleic acid (DNA) breakdown, and DNA synthesis after X irradiation. It is shown that S. typhimurium LT-2 is about four times more sensitive than E. coli B/r but less sensitive than B(s-2). The DNA breakdown is in S. typhimurium LT-2 lower than the postirradiation breakdown of DNA in both E. coli strains and DNA synthesis proceeds in this bacterium in spite of a much lower survival, as in the radioresistant E. coli B/r.
