Transformation of Type Specificity of Meningococci

Alexander, Hattie E.; Redman, Winifred

doi:10.1084/jem.97.6.797

Cited by 38 publications

(12 citation statements)

References 5 publications

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“…Neisseria spp. have been known to be naturally competent for more than half a century (Alexander & Redman, ; Catlin & Cunningham, ). Recent research on the natural competence and transformation of Neisseria has primarily focused on the human pathogens Neisseria meningitidis and Neisseria gonorrhoeae .…”

Section: Caught In Competence – Constitutively Competent Gram‐negativmentioning

confidence: 99%

Cues and regulatory pathways involved in natural competence and transformation in pathogenic and environmental Gram-negative bacteria

Seitz¹,

Blokesch²

2013

FEMS Microbiol Rev

199

201

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Bacterial genomics is flourishing, as whole-genome sequencing has become affordable, readily available and rapid. As a result, it has become clear how frequently horizontal gene transfer (HGT) occurs in bacteria. The potential implications are highly significant because HGT contributes to several processes, including the spread of antibiotic-resistance cassettes, the distribution of toxin-encoding phages and the transfer of pathogenicity islands. Three modes of HGT are recognized in bacteria: conjugation, transduction and natural transformation. In contrast to the first two mechanisms, natural competence for transformation does not rely on mobile genetic elements but is driven solely by a developmental programme in the acceptor bacterium. Once the bacterium becomes competent, it is able to take up DNA from the environment and to incorporate the newly acquired DNA into its own chromosome. The initiation and duration of competence differ significantly among bacteria. In this review, we outline the latest data on representative naturally transformable Gram-negative bacteria and how their competence windows differ. We also summarize how environmental cues contribute to the initiation of competence in a subset of naturally transformable Gram-negative bacteria and how the complexity of the niche might dictate the fine-tuning of the competence window.

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Section: Caught In Competence – Constitutively Competent Gram‐negativmentioning

confidence: 99%

Cues and regulatory pathways involved in natural competence and transformation in pathogenic and environmental Gram-negative bacteria

Seitz¹,

Blokesch²

2013

FEMS Microbiol Rev

199

201

View full text Add to dashboard Cite

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“…However, upon repeated, nonselective transfers thepe gonococci will give rise to a population of predominantly colonial types 3 and 4. Further studies established that types 1 and 2 and the laboratory-adapted colony types differ not only in colonial morphology and pathogenicity but also in autoagglutinability (13,14), ability to irreversibly bind naked deoxyribonucleic acid (DNA) by genetic transformation (18), possession of pili (11,20), resistance to phagocytosis (21), sensitivity to the bactericidal action of antiserum plus complement (22), infectivity for the chicken embryo (3), and attachment to human sperm (9). A major hindrance in studying the pathobiology of the gonococcus is the rapid conversion of the virulent forms (types 1 and 2) to the nonvirulent laboratory-adapted types 3 and 4.…”

mentioning

confidence: 99%

Stability of pathogenic colony types of Neisseria gonorrhoeae in liquid culture by using the parameters of colonial morphology and deoxyribonucleic acid transformation

Scolea¹,

Dul²,

Young³

1975

J Clin Microbiol

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This investigation describes the surveillance of the colonial stability of the pathogenic type 1 from the gonococcal strain F62 to the nonvirulent types 3 and 4 in different liquid media. The maintenance of the colony types was monitored by the parameters of colonial morphology and deoxyribonucleic acid-mediated transformation. During growth in a complex medium, Mueller-Hinton broth, only 46.7% of the gonococcal population remained as type 1 after 12 h. The greatest change in the type 1 colony-forming units correlated with the decline in viable count. The conversion process could not be prevented by the continual maintenance of the gonococcus in logarithmic growth. The frequency of transformation from PRO-(proline) to PRO+ was proportional to this decrease in type 1 colony-forming units. In contrast to Mueller-Hinton medium, the chemically defined minimal medium Gonococcal Genetic Medium (GGM) was capable of maintaining approximately 90% of the gonococcal population in the type 1 colonial form after 16 h of growth, despite a decrease in the viable count. Although the percentage of type 1 appeared to remain constant in GGM, the apparent transformation frequency increased approximately 24-fold from 0 to 12 h of growth. GGM appears to stimulate or maintain competence, as evidenced by an eightfold increase in transformation when cells are exposed to deoxyribonucleic acid in GGM as compared to Mueller-Hinton. In 1963 Kellogg and co-workers (14) classified the gonococcus into four major types (T1, T2, T3, and T,) based on colonial morphology

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“…Citrate was added to inhibit the bacterial desoxyribonuclease action (20). By similar procedures, transforming DNA were extracted from Diplococcus pneumoniae (21), Hemophilus influenzae (22), Neisseria meningitidis (23), and from drug resistant strains of these bacteria (24).…”

Section: Discussionmentioning

confidence: 99%

Mechanism of the Desoxycholate‐citrate Medium for the Isolation of Dysentery Bacilli

Osono¹

1958

Japanese Journal of Microbiology

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In the preceding paper(1), the author described the selection mechanism played by desoxycholate for the isolation of dysentery organis. When colon and dysentery bacilli were suspended in a liquid medium which contained desoxycholate and citrate and were incubated at 37°C for a few hours, a marked difference was found between number of surviving colon bacilli and dysentery organisms. The number of viable coli decreased to one-tenth or to one-twentieth of the initial cell count, but that of dysentery bacilli decreased only to one half of the initial count. The oxygen consumption of the cell suspensions was also suppressed proportionately to the cell count. In accord with these observations it was noted that the stainability of the incubated cells with nucleic acid staining, basic dyes such as methyl green or thionine dyes decreased far more in the case of coli than in dysentery bacilli, and that nucleic acids were actually released into the medium in which the cells were incubated. From these findings, the mechanism of bacterial selection observed with desoxycholate is considered, at least in its principal features, to depend on its nucleic acid-extracting action and . the resulting bactericidal effect of desoxycholate, and on the difference of these effects among species and strains of enteric bacteria.In the present paper the author reports studies on the chemical determination of nucleic acids released into the medium. Some features on the extracting action of desoxycholate and related substances, and the relation of this bile salt action to bacterial activity are discussed in connection with their possible contribution to the selective effect. MATERIALS AND METHODSStrains used. The strains described in the previous papers(1, 2) were used also for the present studies.Media. An improved synthetic medium was used. It consisted of (except otherwise indicated, expressed in terms of M/l) : L-sodium glutamate, 0.01 ; L-aspartic acid, 0.005 ; I,-cystine, 0.0005 ; DL-tryptophan, 0.001 (0.0005 as Lisomer) ; DL-methionine, 0.001 (0.0005 as L-isomer) ; DL-isoleucine, 0.001 (0.0005

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Transformation of Type Specificity of Meningococci

Cited by 38 publications

References 5 publications

Cues and regulatory pathways involved in natural competence and transformation in pathogenic and environmental Gram-negative bacteria

Cues and regulatory pathways involved in natural competence and transformation in pathogenic and environmental Gram-negative bacteria

Stability of pathogenic colony types of Neisseria gonorrhoeae in liquid culture by using the parameters of colonial morphology and deoxyribonucleic acid transformation

Mechanism of the Desoxycholate‐citrate Medium for the Isolation of Dysentery Bacilli

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