期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1970
卷号：67
期号：2
页码：510-516
DOI：10.1073/pnas.67.2.510
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A covalently-closed circular DNA species, banding at a buoyant density of {rho} = 1.709 g/cm3 in CsCl, has been identified in antibiotic-sensitive colonies of E. coli strain AB2463 (rec A-) after mating with a Proteus mirabilis strain that carries the R-factor, R1. This plasmid, which represents a stable segregant of R1 that has lost all of the drug resistance determinants present on the parent R-factor but which has retained its ability to be transferred by conjugation, fulfills the functional definition of the R-factor transfer unit (RTF).
