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Evidence for recombination between a sialidase (nanH) of Actinomyces naeslundii and Actinomyces oris, previously named 'Actinomyces naeslundii genospecies 1 and 2'.

Do T, Henssge U, Gilbert SC, Clark D, Beighton D - FEMS Microbiol. Lett. (2008)

Bottom Line: However, for A. oris significant negative values in tests for neutral selection suggested the rate of mutation in A. oris was greater than in A. naeslundii but with selection against nonsynonymous mutations.This was supported by the observation that the frequency of polymorphic sites in A. oris, which were monomorphic in A. naeslundii was significantly greater than the frequency of polymorphic sites in A. naeslundii which were monomorphic in A. oris (chi(2)=7.011; P=0.00081).The higher proportions of A. oris in the oral biofilm might be explained by the higher mutation rate facilitating an increased ability to respond successfully to environmental stress.

View Article: PubMed Central - PubMed

Affiliation: King's College, School of Medicine and Dentistry, London, UK.

ABSTRACT
Actinomyces spp., predominant members of human oral biofilms, may use extracellular sialidase to promote adhesion, deglycosylate immunoglobulins and liberation of nutrients. Partial nanH gene sequences (1,077 bp) from Actinomyces oris (n=74), Actinomyces naeslundii (n=30), Actinomyces viscosus (n=1) and Actinomyces johnsonii (n=2) which included the active-site region and the bacterial neuraminidase repeats (BNRs) were compared. The sequences were aligned and each species formed a distinct cluster with five isolates having intermediate positions. These five isolates (two A. oris and three A. naeslundii) exhibited interspecies recombination. The nonsynonymous/synonymous ratio was <1 for both A. oris and A. naeslundii indicating that nanH in both species is under stabilizing selective pressure; nonsynonymous mutations are not selected. However, for A. oris significant negative values in tests for neutral selection suggested the rate of mutation in A. oris was greater than in A. naeslundii but with selection against nonsynonymous mutations. This was supported by the observation that the frequency of polymorphic sites in A. oris, which were monomorphic in A. naeslundii was significantly greater than the frequency of polymorphic sites in A. naeslundii which were monomorphic in A. oris (chi(2)=7.011; P=0.00081). The higher proportions of A. oris in the oral biofilm might be explained by the higher mutation rate facilitating an increased ability to respond successfully to environmental stress.

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Recombination events found in nanH of Actinomyces oris strains 60 (EU805671) and 61 (EU805672) and Actinomyces naeslundii strains 51 (EU805620), 25 (EU805612) and CUG 34725 (EU805609). Solid line indicates portion of sequence derived from nanH of A. naeslundii and broken line indicates portion of sequence derived from nanH of A. oris. Insertion in strain 25 between 365 and 1038, in strain 51 between 629 and 1038, in strain 60 between 1 and 477, in strain 61 between 432 and 1038 and between 1 and 655 in CUG 34725. Breakpoints determined using RDP suite of programs with significant evidence (P <0.001) for recombination obtained with ≥5 recombination tests in all cases.
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fig02: Recombination events found in nanH of Actinomyces oris strains 60 (EU805671) and 61 (EU805672) and Actinomyces naeslundii strains 51 (EU805620), 25 (EU805612) and CUG 34725 (EU805609). Solid line indicates portion of sequence derived from nanH of A. naeslundii and broken line indicates portion of sequence derived from nanH of A. oris. Insertion in strain 25 between 365 and 1038, in strain 51 between 629 and 1038, in strain 60 between 1 and 477, in strain 61 between 432 and 1038 and between 1 and 655 in CUG 34725. Breakpoints determined using RDP suite of programs with significant evidence (P <0.001) for recombination obtained with ≥5 recombination tests in all cases.

Mentions: To test for the statistical evidence of recombination in the first instance the Splitstrees method was used and the phi test provided evidence of significant recombination when all strains, except the A. viscosus and A. johnsonii strains, were included in the analysis (P =<10−20). Consideration of A. oris or A. naeslundii strains alone yielded phi values with P =3.43 × 10−6 and P =1.37 × 10−5, respectively, indicating statistically significant evidence of recombination in each of the species. To identify the strains with evidence of recombination we analysed the data of these two species together using the seven programs within the RDP suite and found that only A. naeslundii strains 25, 51 and CCUG 34725 and A. oris strains 60 and 61 gave significant evidence of recombination. The recombination events are summarized in Fig. 2. In the A. naeslundii strains 25, 51 and CCUG 34725 and A. oris strain 60 the recombination event extended beyond the available partial sequences.


Evidence for recombination between a sialidase (nanH) of Actinomyces naeslundii and Actinomyces oris, previously named 'Actinomyces naeslundii genospecies 1 and 2'.

Do T, Henssge U, Gilbert SC, Clark D, Beighton D - FEMS Microbiol. Lett. (2008)

Recombination events found in nanH of Actinomyces oris strains 60 (EU805671) and 61 (EU805672) and Actinomyces naeslundii strains 51 (EU805620), 25 (EU805612) and CUG 34725 (EU805609). Solid line indicates portion of sequence derived from nanH of A. naeslundii and broken line indicates portion of sequence derived from nanH of A. oris. Insertion in strain 25 between 365 and 1038, in strain 51 between 629 and 1038, in strain 60 between 1 and 477, in strain 61 between 432 and 1038 and between 1 and 655 in CUG 34725. Breakpoints determined using RDP suite of programs with significant evidence (P <0.001) for recombination obtained with ≥5 recombination tests in all cases.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2667307&req=5

fig02: Recombination events found in nanH of Actinomyces oris strains 60 (EU805671) and 61 (EU805672) and Actinomyces naeslundii strains 51 (EU805620), 25 (EU805612) and CUG 34725 (EU805609). Solid line indicates portion of sequence derived from nanH of A. naeslundii and broken line indicates portion of sequence derived from nanH of A. oris. Insertion in strain 25 between 365 and 1038, in strain 51 between 629 and 1038, in strain 60 between 1 and 477, in strain 61 between 432 and 1038 and between 1 and 655 in CUG 34725. Breakpoints determined using RDP suite of programs with significant evidence (P <0.001) for recombination obtained with ≥5 recombination tests in all cases.
Mentions: To test for the statistical evidence of recombination in the first instance the Splitstrees method was used and the phi test provided evidence of significant recombination when all strains, except the A. viscosus and A. johnsonii strains, were included in the analysis (P =<10−20). Consideration of A. oris or A. naeslundii strains alone yielded phi values with P =3.43 × 10−6 and P =1.37 × 10−5, respectively, indicating statistically significant evidence of recombination in each of the species. To identify the strains with evidence of recombination we analysed the data of these two species together using the seven programs within the RDP suite and found that only A. naeslundii strains 25, 51 and CCUG 34725 and A. oris strains 60 and 61 gave significant evidence of recombination. The recombination events are summarized in Fig. 2. In the A. naeslundii strains 25, 51 and CCUG 34725 and A. oris strain 60 the recombination event extended beyond the available partial sequences.

Bottom Line: However, for A. oris significant negative values in tests for neutral selection suggested the rate of mutation in A. oris was greater than in A. naeslundii but with selection against nonsynonymous mutations.This was supported by the observation that the frequency of polymorphic sites in A. oris, which were monomorphic in A. naeslundii was significantly greater than the frequency of polymorphic sites in A. naeslundii which were monomorphic in A. oris (chi(2)=7.011; P=0.00081).The higher proportions of A. oris in the oral biofilm might be explained by the higher mutation rate facilitating an increased ability to respond successfully to environmental stress.

View Article: PubMed Central - PubMed

Affiliation: King's College, School of Medicine and Dentistry, London, UK.

ABSTRACT
Actinomyces spp., predominant members of human oral biofilms, may use extracellular sialidase to promote adhesion, deglycosylate immunoglobulins and liberation of nutrients. Partial nanH gene sequences (1,077 bp) from Actinomyces oris (n=74), Actinomyces naeslundii (n=30), Actinomyces viscosus (n=1) and Actinomyces johnsonii (n=2) which included the active-site region and the bacterial neuraminidase repeats (BNRs) were compared. The sequences were aligned and each species formed a distinct cluster with five isolates having intermediate positions. These five isolates (two A. oris and three A. naeslundii) exhibited interspecies recombination. The nonsynonymous/synonymous ratio was <1 for both A. oris and A. naeslundii indicating that nanH in both species is under stabilizing selective pressure; nonsynonymous mutations are not selected. However, for A. oris significant negative values in tests for neutral selection suggested the rate of mutation in A. oris was greater than in A. naeslundii but with selection against nonsynonymous mutations. This was supported by the observation that the frequency of polymorphic sites in A. oris, which were monomorphic in A. naeslundii was significantly greater than the frequency of polymorphic sites in A. naeslundii which were monomorphic in A. oris (chi(2)=7.011; P=0.00081). The higher proportions of A. oris in the oral biofilm might be explained by the higher mutation rate facilitating an increased ability to respond successfully to environmental stress.

Show MeSH
Related in: MedlinePlus