Class Of Plasmids Research Articles

Classification of transferable plasmids conferring resistance to trimethoprim isolated in Great Britain

Classification of transferable plasmids conferring resistance to trimethoprim isolated in Great Britain

Classification of transferable plasmids conferring resistance to trimethoprim isolated in Great Britain

Classification of transferable plasmids conferring resistance to trimethoprim isolated in Great Britain

The molecular nature of heat-labile enterotoxin (LT) of Escherichia coli

ALTHOUGH Escherichia coli is part of the natural flora of the mammalian gut, certain strains cause a cholera-like disease in humans and young farm animals1,2. These E. coli strains carry at least two plasmid-mediated determinants of virulence3,4. One class of plasmids, called Ent, codes for the synthesis of one or more enterotoxins3. These toxins disrupt the fluid balance in the gut resulting in a net efflux of fluid and electrolytes from the gut epithelial cells1. The heat-labile toxin (LT) and cholera toxin have been shown to be identical in their modes of action5 and also to be immunologically similar6,7. Although cholera toxin has been purified and characterised8, it has proved difficult to purify LT and it is not yet fully characterised. Molecular weight estimates for LT range from 20,000 to over 100,000 (refs. 9–11). We report here investigations of the molecular nature of LT carried out by studying an LT gene isolated using recombinant DNA technology12. Using E. coli minicells13, the proteins encoded by the LT gene were identified and the structure of LT was found to be similar to that of cholera toxin.

Evidence for plasmid contribution to the virulence of fish pathogen Vibrio anguillarum.

Analysis of the plasmid deoxyribonucleic acid complement of high- and low- virulent strains of the fish pathogen Vibrio anguillarum showed a correlation between enhanced virulence and the presence of a 50-megadalton plasmid class. All 50-megadalton plasmids isolated from different high-virulent V. anguillarum strains were homologous as judged by the analysis of plasmid deoxyribonucleic acid-deoxyribonucleic acid hybridization. The 50-megadalton plasmid class did not have polynucleotide sequences in common with plasmids of different incompatibility groups.

2,4-D plasmids and persistence.

ACCORDING to the UN Food and Agricultural Organisation production year book of 1974, 27×106 kg of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) were consumed in 1973, making this the most extensively used of all pesticides. One desirable characteristic of 2,4-D, apart from its efficacy as a herbicide, is its lack of persistence in the environment1, due to degradation by a variety of microorganisms. We have argued that in view of the isolation of plasmids encoding the degradation of naturally occurring aliphatic and aromatic compounds2, there exists a class of plasmids which specifically encode the degradation of many man-made derivatives of these compounds, in this instance 2,4-D. Using segregation and transfer analyses we have demonstrated that a plasmid or plasmids is involved in 2,4-D degradation. Clearly bacteria have evolved which can degrade many different pesticides; our results indicate that plasmids may have an important role in this evolution.

Classification of plasmids as an aid to understanding their epidemiology and evolution.

Classification of plasmids as an aid to understanding their epidemiology and evolution.

Characterization and replication control of plasmids from Enterobacter cloacae DF 13.

It has been shown previously that Enterobacter clocacae DF13 harbours at least five different size classes of plasmids. A 45 x 10(6)-Mr self-transmissible R factor determining resistance against tetracyclin, sulfanilamide, streptomycin and chloramphenicol, a 6.0 x 10(6)-Mr bacteriocinogenic factor without sex factors activity and cryptic plasmids in the size classes of Mr 1.3 x10(6), 2.8 x 10(6) and 8.0 x 10(6) respectively. The present work deals with the determination of the homogeneity and molecular relationship of 1.3 x 10(6)-Mr (mini) and 2.8 x 10(6)-Mr (midi) cryptic plasmids and the 6.0 x 10(6)-Mr (maxi) bacteriocinogenic factor, their kinetics of replication and their replication control in response to inhibition of protein synthesis.

Effects of different alleles of the E. coli K12 pol A gene on the replication of non-transferring plasmids.

The effects of eight different polA alleles on the replication of six different non-transferring enterobacterial plasmids have been tested. Using phage P1CM transduction, different allelic polA mutations were introduced into E. coli K12 strains carrying one of several antibiotic resistance plasmids. Plasmid stability in the transductants was examined by testing clones for drug resistance after growth under various conditions. From the results, the R factors may be divided into three different classes. One plasmid is only affected by PolA conditions which inhibit host cell growth, 3 plasmids (from the same compatibility group) are unstable under conditions in which the cells are severely deficient in DNA polymerase I and two other plasmids (compatible with each other and with the other 4) are immediately lost from such transductants and are unstable in a number of others. Furthermore, the plasmids which are most dependent on DNA polymerase I have been shown to replicate in the presence of chloramphenicol and therefore typigy a class of plasmids which includes bacteriocinogenic factors such as ColE1 and CloDF13, resistance determinant RSF1030 and the E. coli 15 minicircular plasmid.

The enterotoxin plasmids of Escherichia coli.

The genetic and molecular nature of the Ent plasmids that determine enterotoxin biosynthesis in strains of Escherichia coli isolated from man and domestic animals has been investigated. At least one transmissible plasmid was present in 90% of 96 toxigenic strains compared with 36% of 204 nontoxigenic strains. Ent plasmids were demonstrated in 17% of the toxigenic strains and often appeared to be selftransmissible. A single Ent plasmid was isolated from 15 enterotoxigenic strains by conjugation experiments. The class of Ent plasmids that determines the production of both heat-stable and heat-labile enterotoxins was homogeneous and consisted of a single DNA species with an approximate molecular weight of 6.0 x 107 daltons. The class of Ent plasmids that codes for heat-stable enterotoxins only was heterogeneous and consisted of a single species of DNA that ranged in size from 2.1 to 8.0 x 107 daltons.

Genetic evidence for two types of gene arrangements in new λ dv plasmid mutants

Several hundred new λ dv plasmid derivatives of bacteriophage λ were isolated and characterized genetically. Marker rescue tests show that they are deletion variants retaining approximately one-tenth of the λ phage genome, a segment including the genes for DNA replication ( O and P ), and part or all of the immunity region ( i ). A recombination test of the arrangement of genes in λ dv plasmids was developed. Using this test, two classes of plasmids with different gene arrangements were identified. The sequence among simple λ dv plasmids is i O P , or a tandem repetition, i O P i O P …, if the λ dv is an oligomer. Members of the other class contain inverted repeats, two monomer sequences joined head to head ( i O P P O i ). λ dv plasmids were isolated from phage of different genotypes: λ + , λ nin 5, and λ att-red deletion nin 5. The genotype of the phage parent determines the relative frequencies of the two types of λ dv variants. Inverted repeats comprise approximately three-fourths of the λ dv plasmids isolated from λ nin 5, but less than one-tenth of the isolates from λ + or from λ nin 5 att-red deletion . † Present address.

Interactions of group H resistance factors with the F factor.

The four R factors described in this paper form a single compatibility group which has been previously designated group H. Recombination was demonstrated between any pair of the plasmids TP117, 123, and 124. In contrast, TP116 did not appear to recombine with any other members of the group. TP117, 123, and 124 usually displaced the F factor from Escherichia coli K-12F(+), while TP116 and F coexisted stably in that strain. Deoxyribonucleic acid reassociation experiments showed minimal homology between F and the four group H plasmids. The results indicate that there are limitations to using incompatibility alone for classification of bacterial plasmids.

Cell genetics and hereditary symbiosis.

ArticlesCell Genetics and Hereditary SymbiosisJoshua LederbergJoshua LederbergPublished Online:01 Oct 1952https://doi.org/10.1152/physrev.1952.32.4.403MoreSectionsPDF (5 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByTurn on the Mtr pathway genes under pLacI promoter in Shewanella oneidensis MR-125 July 2018 | Bioresources and Bioprocessing, Vol. 5, No. 1Intracellular Delivery by Membrane Disruption: Mechanisms, Strategies, and Concepts27 July 2018 | Chemical Reviews, Vol. 118, No. 16Evolution of Plasmid-Mediated Antibiotic Resistance in the Clinical ContextTrends in MicrobiologyPlasmid Cloning Vectors30 January 2018Plasmid DNA Manufacturing for Indirect and Direct Clinical ApplicationsHuman Gene Therapy, Vol. 28, No. 10Perspectiva histórica del origen evolutivo de la resistencia a antibióticos1 July 2017 | Revista Colombiana de Biotecnología, Vol. 19, No. 2The Induced Synthesis of Proteins22 November 2006The dynamics of symbiosis: an historical overviewCanadian Journal of Botany, Vol. 82, No. 8When phage, plasmids, and transposons collide: genomic islands, and conjugative- and mobilizable-transposons as a mosaic continuumPlasmid, Vol. 48, No. 3Paul Buchner (1886–1978) and hereditary symbiosis in insects23 July 2002 | International Microbiology, Vol. 5, No. 3Bacterial plasmids: their extraordinary contribution to molecular geneticsGene, Vol. 135, No. 1-2Plasmid formation from bacteriophage λ as a result of interference by resident plasmid λdvVirology, Vol. 47, No. 3Mycetomal micro-organisms and total lipid and phospholipid in granary weevils, Sitophilus granarius L. (Coleoptera)Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, Vol. 41, No. 2Plasmid formation from bacteriophage ? in Escherichia coliMGG Molecular & General Genetics, Vol. 114, No. 4Ribonucleic acids from the mitochondria of bleached Euglena gracilis zBiochimica et Biophysica Acta (BBA) - Nucleic Acids and Protein Synthesis, Vol. 217, No. 1A genetic approach to endocellular symbiosisExperimental Parasitology, Vol. 17, No. 1Vererbung durch Kerngene und das Problem der ausserkaryotischen Vererbung bei Culex pipiensZeitschrift f�r Induktive Abstammungs- und Vererbungslehre, Vol. 88, No. 4Physiological and Genetic Adaptability in the Fungi13 September 2018 | Mycologia, Vol. 49, No. 1THE PROBABLE CHEMICAL NATURE OF CROWN-GALL TUMOR-INDUCING PRINCIPLE1 October 1953 | American Journal of Botany, Vol. 40, No. 8 More from this issue > Volume 32Issue 4October 1952Pages 403-430 Copyright & PermissionsCopyright © 1952 the American Physiological Societyhttps://doi.org/10.1152/physrev.1952.32.4.403PubMed13003535History Published online 1 October 1952 Published in print 1 October 1952 Metrics