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  • 1
    Electronic Resource
    Electronic Resource
    Sex in Escherichia coli does not disrupt the clonal structure of the population: evidence from random amplified polymorphic DNA and restriction-fragment-length polymorphism (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 440-448 
    Details
    ISSN: 1432-1432
    Keywords: Escherichia coli ; RAPD ; RFLP ; Clonal theory ; Recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Analysis of the Escherichia coli population by multilocus enzyme electrophoresis (MLEE) has established its clonal organization, but there is increasing evidence that horizontal DNA transfer occurs in E. coli. We have assessed the genetic structure of the species E. coli and determined the extent to which recombination can affect the clonal structure of bacteria. A panel of 72 E. coli strains from the ECOR collection was characterized by random amplified polymorphic DNA (RAPD) and restriction-fragment-length polymorphism (RFLP) of the ribosomal RNA gene (rrn) regions. These strains have been characterized by MLEE and are assumed to reflect the range of genotypic variation in the species as a whole. Statistical analysis, including factorial analysis of correspondence (FAC) and hierarchical classifications, established that the data obtained with the three genetic markers are mutually corroborative, thus providing compelling evidence that horizontal transfer does not disrupt the clonal organization of the population. However, there is a gradient of correlation between the different classifications which ranges from the highly clonal structure of 132 group strains causing extraintestinal infections in humans to the less-stringent structure of B1 group strains that came mainly from nonprimate mammals. This group (B1) appears to be the framework from which the remaining non-A group strains have emerged. These results indicate that RAPD analysis is well suited to intraspecies characterization of E. coli. Lastly, treating the RAPD data by FAC allowed description of subgroup-specific DNA fragments which can be used, in a strategy comparable to positional cloning, to isolate virulence genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00160315
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  • 2
    Electronic Resource
    Electronic Resource
    The absence of correlation between allozyme and rrn RFLP analysis indicates a high gene flow rate within human clinical Pseudomonas aeruginosa isolates (1993)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 110 (1993), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Two hundred and fifty seven human clinical Pseudomonas aeruginosa strains isolated between 1984 and 1990 in several regions of France, as well as two reference strains, were studied by computer-assisted statistical analysis of the data from their esterase electrophoretic patterns and rrn restriction fragment length polymorphisms. No correlation was found between the two sets of data except for some strians of serotype O12 which, thus, may constttute a distinct group within the species. This absence of correlation indicates a high gene flow rate within human isolates of the P. aeruginosa species. A possible explanation is that, because of an as yet unidentified selective advantage, the esterase loci are a major target for recombinational events. Alternatively, horizontal genetic transfers between strains may have occured at so high a rate that the clonal structure usually observed in bacterial populations has been disrupted. This study highlights clearly the need for caution in inferring bacterial population structure from any single class of genetic markers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1993.tb06334.x
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  • 3
    Electronic Resource
    Electronic Resource
    Purification and characterization of three carboxylesterases from Enterobacteriaceae (1993)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 108 (1993), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The carboxylesterases from Proteus vulgaris, Salmonella enterica and Citrobacter amalonaticus were purified 104-, 95- and 120-fold, respectively by chromatography. The enzymes had similar catalytic activities but differed considerably in their inactivation by heat, di-isopropyl fluorophosphate and Cd2+, Zn2+, Hg2+ and Cu2+. Quantitative neutralization of hydrolytic activity with specific immunoglobulins indicated that the three enzymes were antigenically distinct.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1993.tb06077.x
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  • 4
    Electronic Resource
    Electronic Resource
    Clonal relationships among Escherichia coli serogroup 06 isolates from human and animal infections (1991)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 80 (1991), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: The clonal relationship of thirty E. coli strains of 0 antigen serotype 06 isolated from human, dog, pig or cow infections were investigated. Two main clones with serotypes 06:H1 or 06:H31, H− were identified. Isolates from humans, dogs, pigs and cows were found in both clones, indicating that animals are a possible source for human extraintestinal Escherichia coli strains. Two human ETEC (06:H16) and two pig isolates (06:H10) were not related to the 06:H1 or 06:H31, H−E. coli clones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1991.tb04666.x
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  • 5
    Electronic Resource
    Electronic Resource
    Substitution of Met-69 by Ala or Gly in TEM-1 β-lactamase confer an increased susceptibility to clavulanic acid and other inhibitors (2002)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 211 (2002), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In some inhibitor-resistant TEM-derived β-lactamases, Met-69 is substituted by Leu, Ile or Val. Residue 69 is located in a region of strong structural constraints, at the beginning of H2 α-helix, and in the vicinity of B3 and B4 β-strands. Analysis of the three-dimensional structure of TEM-1 β-lactamase suggests that alteration of the substrate-binding site can be produced by changes of the size of residue 69 side chain. Met-69 was substituted by alanine or glycine in TEM-Bs β-lactamase (a TEM-1-related enzyme) using site-directed mutagenesis. The minimum inhibitory concentrations of the mutants compared with the wild-type revealed an increased susceptibility to β-lactamase inhibitor–β-lactam combinations and to first-generation cephalosporins. Comparing the Met69Ala and Met69Gly β-lactamases with TEM-Bs, Km constants of the mutants showed an increased affinity for most β-lactams but the kcat for most substrates did not change substantially. Mutants also demonstrated lower IC50 for the three inhibitors (clavulanic acid, tazobactam and sulbactam). The two substitutions of the residue 69 by alanine and glycine had a noticeable effect on Km values of TEM-Bs β-lactamase, and on affinity for β-lactamase inhibitors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2002.tb11196.x
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  • 6
    Electronic Resource
    Electronic Resource
    Panmictic structure of Helicobacter pylori demonstrated by the comparative study of six genetic markers (1998)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 161 (1998), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We compared the classifications of strains obtained by analysis of several genetic markers to demonstrate the panmictic structure of Helicobacter pylori, previously suggested by the study of multilocus enzyme electrophoresis. A series of 39 strains, including 37 clinical isolates from patients with gastritis or ulcers from two regions of France, reference strain CIP 101260 and the Sydney strain (strain SS1), were used. They were studied by restriction fragment length polymorphism analysis of ribosomal DNA (ribotyping) using HindIII and HaeIII, by polymorphism analysis of the ureA-ureB and flaA genes by PCR-RFLP using HaeIII and MboI, by vacA genotyping and by the presence or absence of the cagA gene and of the insertion sequence IS605 detected by PCR. There was a high level of genetic polymorphism over the studied strains, with 38 ribotypes, 38 restriction profiles for the ureA-ureB gene, 19 restriction profiles for the flaA gene and five combinations of the signal and mid-region sequences of the vacA gene. Factorial analysis of correspondence and hierarchical clustering performed using each marker revealed that the different classifications of the strains were not correlated. This suggests there is much genetic recombination between strains and supports the hypothesis of a panmictic structure for the H. pylori species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1998.tb12953.x
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  • 7
    Electronic Resource
    Electronic Resource
    HIV-1 genetic diversity in Western Brittany, France (2002)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 34 (2002), S. 0 
    Details
    ISSN: 1574-695X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We describe human immunodeficiency virus type 1 (HIV-1) diversity in Western Brittany, France, and trace the dissemination of HIV-1 non-B subtype infection. The strategy for HIV-1 subtyping used involved subtype specific enzyme immunoassays, heteroduplex mobility assays and phylogenetic analysis of the sequences of env encoding the V3 loop region. Samples were obtained from 567 patients: 465 (82%) were of subtype B and 66 (11.6%) were not (20 were subtype A, 11 subtype C, four subtype D, seven subtype F, five subtype G and 19 others with circulating recombinant forms: 4CRF01_AE, 11CRF02_AG, 1H, 3CRF11_cpx). These findings are consistent with other studies of French populations. There is an epidemiological correlation between subtype B and homosexual or heterosexual contamination in France and between non-B subtype and heterosexual contamination in Africa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-695X.2002.tb00604.x
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  • 8
    Electronic Resource
    Electronic Resource
    The electrophoretic polymorphism of bacterial esterases (1995)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 16 (1995), S. 0 
    Details
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: The specific activities of esterases and certain other molecular properties including immunospecificity indicate that the electrophoretic variations of these enzymes in bacterial populations are the result of allelic variations at specific gene loci. The esterase polymorphism of Enterobacteriaceae and some other species isolated from man or animals demonstrates that esterases can distinguish between bacteria at the species or subspecies level, both by their biochemical properties and by their electrophoretic differences. The esterase data complement DNA hybridization studies and agree with ribosomal DNA polymorphism, especially for delineating a phylogenetically distinct group of highly pathogenic strains in Escherichia coli. A two-dimensional electrophoretic profile obtained by establishing a direct correspondence between homologous esterase bands resolved by independent runs of isoelectric focusing and standard electrophoresis considerably improves the detection of allelic variations, whereas protein titration curves (electrophoresis in pH gradient) can be used to demonstrate the real electrophoretic homogeneity of allozymes or evalue their molecular relationship in terms of apparent amino acid substitutions. This overview establishes that esterases, by their significant electrophoretic polymorphism, are reliable molecular markers for systematics and epidemiology, and are suitable enzyme systems for studying population genetics and phylogeny.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6976.1995.tb00153.x
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  • 9
    Electronic Resource
    Electronic Resource
    Electrophoretic patterns of esterases and lactate- and malate-dehydrogenases fromAlcaligenes species (1993)
    Springer
    Current microbiology 27 (1993), S. 79-84 
    Details
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Esterases and lactate-(LDH) and malate-(MDH) dehydrogenases of 34 strains ofAlcaligenes faecalis, 16 strains ofA. denitrificans subspxylosoxydans (A. xylosoxydans), 5 strains ofA. piechaudii, and 10 strains ofA. denitrificans subspdenitrificans (A. denitrificans) were analyzed by horizontal polyacrylamide-agarose gel electrophoresis. Four types of esterases were identified inA. faecalis, 3 inA. xylosoxydans, 3 inA. piechaudii, and 14 inA. denitrificans by their spectra of hydrolytic activity towards five synthetic substrates. Four variants of MDH and no LDH variant were detected in the strains ofA. faecalis. MDH and LDH were distributed in three variants among the strains ofA. xylosoxydans. Only one variant of MDH and two variants of LDH were found inA. piechaudii strains. Four variants of MDH and one variant of LDH were identified in the strains ofA. denitrificans. A correspondence analysis of these results allowed precise identification of all the strains within these four species ofAlcaligenes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01570862
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  • 10
    Electronic Resource
    Electronic Resource
    Computer-assisted statistical analyses of enzyme and ribosomal DNA electrophoretic polymorphism in Yersinia (1991)
    Weinheim : Wiley-Blackwell
    Electrophoresis 12 (1991), S. 264-269 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The intra- and inter-species differentiation of 90 strains of Yersinia belonging to six species were studied independently by computer-assisted statistical analysis of data from enzyme electrophoretic polymorphism and ribosomal DNA (rDNA) restriction fragment length polymorphism. Two corresondence analyses (CA) demonstrated the concordance between the bacterial classification obtained from enzymatic and genomic data. This concordance was reinforced by an algorithm of the correspondence established between the two dendrograms drawn from previous computations. Comparison of CA with similarity analysis (also called “numerical taxonomy”) indicated that the intra- and inter-species differentiation obtained by the two methods are similar. The advantage of CA is that it gives a synthetic geometrical representation of the results (factorial planes), displaying both the main features of the clusters of strains (location and dispersion) and their essential character (i.e.: enzyme electrophoretic variant, rDNA fragment size).
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150120406
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