| Literature DB >> 4601591 |
Abstract
The DNA of the thermosensitive R factor, Rts1, has been examined by the technique of sedimentation in alkaline sucrose density gradients. Rts1 DNA was found as closed covalent circles in only a few copies per cell in an Escherichia coli host at the permissive temperature. Rts1 DNA appears to be synthesized at the nonpermissive temperature, but was not found as closed covalent circles. However, circular DNA could be recovered upon shift down to the permissive temperature. The large number of plasmid-negative cells which accumulate after prolonged culture at non-permissive temperature may be due to a strong selective pressure favoring the growth of rare R(-) segregants.Entities:
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Year: 1974 PMID： 4601591 PMCID： PMC388490 DOI： 10.1073/pnas.71.6.2515
Source DB: PubMed Journal: Proc Natl Acad Sci U S A ISSN： 0027-8424 Impact factor: 11.205