Search results for "Plasmids"
showing 9 items of 209 documents
Single- and Double-Strand Breaks of Dry DNA Exposed to Protons at Bragg-Peak Energies
2017
International audience; Ultrathin layers (<20 nm) of pBR322 plasmid DNA were deposited onto 2.5 μm thick polyester films and exposed to proton Bragg-peak energies (90–3000 keV) at various fluences. A quantitative analysis of radio-induced DNA damage is reported here in terms of single- and double-strand breaks (SSB and DSB, respectively). The corresponding yields as well as G-values and the cross sections exhibit fairly good agreement with the rare available data, stemming from close experimental conditions, namely, based on α particle irradiation. SSB/DSB rates appear to be linear when plotted against linear energy transfer (LET) in the whole energy range studied. All the data present a ma…
A common virulence plasmid in biotype 2 Vibrio vulnificus and its dissemination aided by a conjugal plasmid.
2007
ABSTRACT Strains of Vibrio vulnificus , a marine bacterial species pathogenic for humans and eels, are divided into three biotypes, and those virulent for eels are classified as biotype 2. All biotype 2 strains possess one or more plasmids, which have been shown to harbor the biotype 2-specific DNA sequences. In this study we determined the DNA sequences of three biotype 2 plasmids: pR99 (68.4 kbp) in strain CECT4999 and pC4602-1 (56.6 kb) and pC4602-2 (66.9 kb) in strain CECT4602. Plasmid pC4602-2 showed 92% sequence identity with pR99. Curing of pR99 from strain CECT4999 resulted in loss of resistance to eel serum and virulence for eels but had no effect on the virulence for mice, an anim…
Preceding Host History of Conjugative Resistance Plasmids Affects Intra- and Interspecific Transfer Potential from Biofilm
2023
Conjugative plasmids can confer antimicrobial resistance (AMR) to their host bacterium. The plasmids disperse even between distantly related host species, rescuing the host from otherwise detrimental effects of antibiotics. Little is known about the role of these plasmids in the spread of AMR during antibiotic treatment. One unstudied question is whether the past evolutionary history of a plasmid in a particular species creates host specificity in its rescue potential or if interspecific coevolution can improve interspecific rescues. To study this, we coevolved the plasmid RP4 under three different host settings; solely Escherichia coli or Klebsiella pneumoniae, or alternating between both …
Counteracting the horizontal spread of bacterial antibiotic resistance with conjugative plasmid-dependent bacteriophages
2016
Viruses are ancient parasites that have influenced the evolution of contemporary and archaic forms of life
2010
Plasmid diversity in Vibrio vulnificus biotypes.
2009
Vibrio vulnificus is a heterogeneous bacterial species that can be virulent for humans and fish. Virulence in fish seems to rely on a recently described plasmid that can be transmitted between strains, aided by a conjugative plasmid. The main objective of this work was to analyse the plasmid content of a wide collection of strains from the three biotypes of the species, as well as to identify putative conjugative and virulence plasmids by means of Southern hybridization with specific probes and sequence analysis of selected gene markers. We found 28 different plasmid profiles in a total of 112 strains, which were relatively biotype- or serovar-specific. Biotype 1 lacked high-molecular-mass…
Indirect Selection against Antibiotic Resistance via Specialized Plasmid-Dependent Bacteriophages
2021
Antibiotic resistance genes of important Gram-negative bacterial pathogens are residing in mobile genetic elements such as conjugative plasmids. These elements rapidly disperse between cells when antibiotics are present and hence our continuous use of antimicrobials selects for elements that often harbor multiple resistance genes. Plasmid-dependent (or male-specific or, in some cases, pilus-dependent) bacteriophages are bacterial viruses that infect specifically bacteria that carry certain plasmids. The introduction of these specialized phages into a plasmid-abundant bacterial community has many beneficial effects from an anthropocentric viewpoint: the majority of the plasmids are lost whil…
Molecular evolution of aphids and their primary (Buchnera sp.) and secondary endosymbionts: Implications for the role of symbiosis in insect evolution
2001
Aphids maintain an obligate, endosymbiotic association with Buchnera sp., a bacterium closely related to Escherichia coli. Bacteria are housed in specialized cells of organ-like structures called bacteriomes in the hemocoel of the aphid and are maternally transmitted. Phylogenetic studies have shown that the association had a single origin, dated about 200-250 million years ago, and that host and endosymbiont lineages have evolved in parallel since then. However, the pattern of deepest branching within the aphid family remains unsolved, which thereby hampers an appraisal of, for example, the role played by horizontal gene transfer in the early evolution of Buchnera. The main role of Buchner…
Double copies of blaKPC-3::Tn4401a on an IncX3 plasmid in Klebsiella pneumoniae successful clone ST512 from Italy
2015
ABSTRACT A carbapenem-resistant sequence type 512 (ST512) Klebsiella pneumoniae carbapenemase 3 (KPC-3)-producing K. pneumoniae strain showing a novel variant plasmid content was isolated in Palermo, Italy, in 2014. ST512 is a worldwide successful clone associated with the spread of bla KPC genes located on the IncFIIk pKpQIL plasmid. In our ST512 strain, the bla KPC-3 gene was unusually located on an IncX3 plasmid, whose complete sequence was determined. Two copies of bla KPC-3 ::Tn 4401a caused by intramolecular transposition events were detected in the plasmid.