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Chromosomal rearrangements formed by rrn recombination do not improve replichore balance in host-specific Salmonella enterica serovars.

Matthews TD, Edwards R, Maloy S - PLoS ONE (2010)

Bottom Line: Only 48 out of 1,440 possible arrangement types were identified in 212 host-specific strains.While the replichores of most naturally-occurring arrangement types were well-balanced, most theoretical arrangement types had imbalanced replichores.Furthermore, the most common types of rearrangements did not change replichore balance.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Center for Microbial Sciences, San Diego State University, San Diego, California, United States of America.

ABSTRACT

Background: Most of the ∼2,600 serovars of Salmonella enterica have a broad host range as well as a conserved gene order. In contrast, some Salmonella serovars are host-specific and frequently exhibit large chromosomal rearrangements from recombination between rrn operons. One hypothesis explaining these rearrangements suggests that replichore imbalance introduced from horizontal transfer of pathogenicity islands and prophages drives chromosomal rearrangements in an attempt to improve balance.

Methodology/principal findings: This hypothesis was directly tested by comparing the naturally-occurring chromosomal arrangement types to the theoretically possible arrangement types, and estimating their replichore balance using a calculator. In addition to previously characterized strains belonging to host-specific serovars, the arrangement types of 22 serovar Gallinarum strains was also determined. Only 48 out of 1,440 possible arrangement types were identified in 212 host-specific strains. While the replichores of most naturally-occurring arrangement types were well-balanced, most theoretical arrangement types had imbalanced replichores. Furthermore, the most common types of rearrangements did not change replichore balance.

Conclusions/significance: The results did not support the hypothesis that replichore imbalance causes these rearrangements, and suggest that the rearrangements could be explained by aspects of a host-specific lifestyle.

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Related in: MedlinePlus

Expected species accumulation curve of naturally-occurring arrangement types.The moment-based estimator of species richness, τ (h), was computed using EstimateS version 8.2 [55] with 95% confidence intervals (dashed lines). The number of observed arrangement types has not reached a plateau, and will likely increase as more host-specific Salmonella strains are characterized.
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pone-0013503-g003: Expected species accumulation curve of naturally-occurring arrangement types.The moment-based estimator of species richness, τ (h), was computed using EstimateS version 8.2 [55] with 95% confidence intervals (dashed lines). The number of observed arrangement types has not reached a plateau, and will likely increase as more host-specific Salmonella strains are characterized.

Mentions: While each of the analyzed host-specific serovars has a most common arrangement type, a number of strains in each serovar have unique arrangement types. However, out of the 1,440 possible rrn arrangement types that can occur, only 48 have been identified so far in naturally-occurring strains of host-specific Salmonella serovars. How much diversity would be found if the arrangement types of more strains were determined? An arrangement type accumulation curve (Figure 3) and the estimation of the arrangement type richness computed using EstimateS ver. 8.2 [51] suggest that an additional 196 arrangement types (with a 95% confidence interval of 49–783 additional arrangement types) occur naturally in host-specific Salmonella serovars. If this estimate is correct, more than 80% of possible arrangement types do not occur naturally.


Chromosomal rearrangements formed by rrn recombination do not improve replichore balance in host-specific Salmonella enterica serovars.

Matthews TD, Edwards R, Maloy S - PLoS ONE (2010)

Expected species accumulation curve of naturally-occurring arrangement types.The moment-based estimator of species richness, τ (h), was computed using EstimateS version 8.2 [55] with 95% confidence intervals (dashed lines). The number of observed arrangement types has not reached a plateau, and will likely increase as more host-specific Salmonella strains are characterized.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2957434&req=5

pone-0013503-g003: Expected species accumulation curve of naturally-occurring arrangement types.The moment-based estimator of species richness, τ (h), was computed using EstimateS version 8.2 [55] with 95% confidence intervals (dashed lines). The number of observed arrangement types has not reached a plateau, and will likely increase as more host-specific Salmonella strains are characterized.
Mentions: While each of the analyzed host-specific serovars has a most common arrangement type, a number of strains in each serovar have unique arrangement types. However, out of the 1,440 possible rrn arrangement types that can occur, only 48 have been identified so far in naturally-occurring strains of host-specific Salmonella serovars. How much diversity would be found if the arrangement types of more strains were determined? An arrangement type accumulation curve (Figure 3) and the estimation of the arrangement type richness computed using EstimateS ver. 8.2 [51] suggest that an additional 196 arrangement types (with a 95% confidence interval of 49–783 additional arrangement types) occur naturally in host-specific Salmonella serovars. If this estimate is correct, more than 80% of possible arrangement types do not occur naturally.

Bottom Line: Only 48 out of 1,440 possible arrangement types were identified in 212 host-specific strains.While the replichores of most naturally-occurring arrangement types were well-balanced, most theoretical arrangement types had imbalanced replichores.Furthermore, the most common types of rearrangements did not change replichore balance.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Center for Microbial Sciences, San Diego State University, San Diego, California, United States of America.

ABSTRACT

Background: Most of the ∼2,600 serovars of Salmonella enterica have a broad host range as well as a conserved gene order. In contrast, some Salmonella serovars are host-specific and frequently exhibit large chromosomal rearrangements from recombination between rrn operons. One hypothesis explaining these rearrangements suggests that replichore imbalance introduced from horizontal transfer of pathogenicity islands and prophages drives chromosomal rearrangements in an attempt to improve balance.

Methodology/principal findings: This hypothesis was directly tested by comparing the naturally-occurring chromosomal arrangement types to the theoretically possible arrangement types, and estimating their replichore balance using a calculator. In addition to previously characterized strains belonging to host-specific serovars, the arrangement types of 22 serovar Gallinarum strains was also determined. Only 48 out of 1,440 possible arrangement types were identified in 212 host-specific strains. While the replichores of most naturally-occurring arrangement types were well-balanced, most theoretical arrangement types had imbalanced replichores. Furthermore, the most common types of rearrangements did not change replichore balance.

Conclusions/significance: The results did not support the hypothesis that replichore imbalance causes these rearrangements, and suggest that the rearrangements could be explained by aspects of a host-specific lifestyle.

Show MeSH
Related in: MedlinePlus