| 1. |
- Alsmark, Cecilia M., et al.
(författare)
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The louse-borne human pathogen Bartonella quintana is a genomic derivative of the zoonotic agent Bartonella henselae
- 2004
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 101:26, s. 9716-9721
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Tidskriftsartikel (refereegranskat)abstract
- We present the complete genomes of two human pathogens, Bartonella quintana (1,581,384 bp) and Bartonella henselae (1,931,047 bp). The two pathogens maintain several similarities in being transmitted by insect vectors, using mammalian reservoirs, infecting similar cell types (endothelial cells and erythrocytes) and causing vasculoproliferative changes in immunocompromised hosts. A primary difference between the two pathogens is their reservoir ecology. Whereas B. quintana is a specialist, using only the human as a reservoir, B. henselae is more promiscuous and is frequently isolated from both cats and humans. Genome comparison elucidated a high degree of overall similarity with major differences being B. henselae specific genomic islands coding for filamentous hemagglutinin, and evidence of extensive genome reduction in B. quintana, reminiscent of that found in Rickettsia prowazekii. Both genomes are reduced versions of chromosome I from the highly related pathogen Brucella melitensis. Flanked by two rRNA operons is a segment with similarity to genes located on chromosome II of B. melitensis, suggesting that it was acquired by integration of megareplicon DNA in a common ancestor of the two Bartonella species. Comparisons of the vector-host ecology of these organisms suggest that the utilization of host-restricted vectors is associated with accelerated rates of genome degradation and may explain why human pathogens transmitted by specialist vectors are outnumbered by zoonotic agents, which use vectors of broad host ranges.
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| 2. |
- Andersson, Elin M, et al.
(författare)
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Does a multi-component intervention including pictorial risk communication about subclinical atherosclerosis improve perceptions of cardiovascular disease risk without deteriorating efficacy beliefs?
- 2024
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Ingår i: Social Science and Medicine. - : Elsevier. - 0277-9536 .- 1873-5347. ; 341
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Tidskriftsartikel (refereegranskat)abstract
- Background: Pictorial communication about subclinical atherosclerosis can improve cardiovascular disease (CVD) risk, but whether it leads to long-term shifts in self-rated CVD risk (risk perception) and beliefs about possibility to influence personal risk (efficacy beliefs) is unknown.Purpose: To study the impact of personalized color-coded and age-related risk communication about atherosclerosis and motivational conversation, compared to traditional risk factor-based communication, on risk perception and efficacy beliefs. Also, whether risk perception increases with message severity.Method: The effect of the pragmatic RCT Visualization of Asymptomatic Atherosclerotic Disease for Optimum Cardiovascular Prevention (VIPVIZA) was analyzed using a linear mixed effects model with risk perception and efficacy believes at 1-year and 3-year follow up as dependent variables. Participants’ (n = 3532) CVD risk perception and efficacy beliefs were assessed with visual analog scales (0–10). Fixed effects were group (intervention vs control), time point (1 year or 3 years) and interaction between group and time point. Further, the models were adjusted for corresponding baseline measurement of the dependent variable and a baseline × time point interaction. Effect of pictorial color-coded risk in the intervention group was investigated using a corresponding mixed effects model, but with pictorial risk group (message severity) as exposure instead of intervention group.Results: After one year, the intervention group rated their CVD risk as higher (m = 0.46, 95% CI 0.32–0.59), with an effect also after 3 years (m = 0.57, 95% CI 0.43–0.70). The effect was consistent in stratified analyses by sex and education. Overall, no effect on efficacy beliefs was observed. In the intervention group, differences in CVD risk perception were found between participants with different color-coded risk messages on atherosclerosis status.Conclusion: Personalized, color-coded and age-related risk communication about atherosclerosis had an effect on risk perception with an effect also after 3 years, whereas overall, no effect on efficacy beliefs was observed.
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| 3. |
- Andersson, Siv GE, et al.
(författare)
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The genome sequence of Rickettsia prowazekii and the origin of mitochondria
- 1998
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 396:6707, s. 133-140
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Tidskriftsartikel (refereegranskat)abstract
- We describe here the complete genome sequence (1,111,523 base pairs) of the obligate intracellular parasite Rickettsia prowazekii, the causative agent of epidemic typhus. This genome contains 834 protein-coding genes. The functional profiles of these genes show similarities to those of mitochondrial genes: no genes required for anaerobic glycolysis are found in either R. prowazekii or mitochondrial genomes, but a complete set of genes encoding components of the tricarboxylic acid cycle and the respiratory-chain complex is found in R. prowazekii. In effect, ATP production in Rickettsia is the same as that in mitochondria. Many genes involved in the biosynthesis and regulation of biosynthesis of amino acids and nucleosides in free-living bacteria are absent from R. prowazekii and mitochondria. Such genes seem to have been replaced by homologues in the nuclear (host) genome. The R. prowazekii genome contains the highest proportion of non-coding DNA (24%) detected so far in a microbial genome. Such non-coding sequences may be degraded remnants of 'neutralized' genes that await elimination from the genome. Phylogenetic analyses indicate that R. prowazekii is more closely related to mitochondria than is any other microbe studied so far.
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| 4. |
- Berglund, Eva C., et al.
(författare)
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Genome dynamics of Bartonella grahamii in micro-populations of woodland rodents
- 2010
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 11, s. 152-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Rodents represent a high-risk reservoir for the emergence of new human pathogens. The recent completion of the 2.3 Mb genome of Bartonella grahamii, one of the most prevalent blood-borne bacteria in wild rodents, revealed a higher abundance of genes for host-cell interaction systems than in the genomes of closely related human pathogens. The sequence variability within the global B. grahamii population was recently investigated by multi locus sequence typing, but no study on the variability of putative host-cell interaction systems has been performed. Results: To study the population dynamics of B. grahamii, we analyzed the genomic diversity on a whole-genome scale of 27 B. grahamii strains isolated from four different species of wild rodents in three geographic locations separated by less than 30 km. Even using highly variable spacer regions, only 3 sequence types were identified. This low sequence diversity contrasted with a high variability in genome content. Microarray comparative genome hybridizations identified genes for outer surface proteins, including a repeated region containing the fha gene for filamentous hemaggluttinin and a plasmid that encodes a type IV secretion system, as the most variable. The estimated generation times in liquid culture medium for a subset of strains ranged from 5 to 22 hours, but did not correlate with sequence type or presence/absence patterns of the fha gene or the plasmid. Conclusion: Our study has revealed a geographic microstructure of B. grahamii in wild rodents. Despite near-identity in nucleotide sequence, major differences were observed in gene presence/absence patterns that did not segregate with host species. This suggests that genetically similar strains can infect a range of different hosts.
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| 5. |
- Berglund, Eva C., et al.
(författare)
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Run-off replication of host-adaptability genes is associated with gene transfer agents in the genome of mouse-infecting Bartonella grahamii
- 2009
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Ingår i: PLoS genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 5:7, s. e1000546-
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Tidskriftsartikel (refereegranskat)abstract
- The genus Bartonella comprises facultative intracellular bacteria adapted to mammals, including previously recognized and emerging human pathogens. We report the 2,341,328 bp genome sequence of Bartonella grahamii, one of the most prevalent Bartonella species in wild rodents. Comparative genomics revealed that rodent-associated Bartonella species have higher copy numbers of genes for putative host-adaptability factors than the related human-specific pathogens. Many of these gene clusters are located in a highly dynamic region of 461 kb. Using hybridization to a microarray designed for the B. grahamii genome, we observed a massive, putatively phage-derived run-off replication of this region. We also identified a novel gene transfer agent, which packages the bacterial genome, with an over-representation of the amplified DNA, in 14 kb pieces. This is the first observation associating the products of run-off replication with a gene transfer agent. Because of the high concentration of gene clusters for host-adaptation proteins in the amplified region, and since the genes encoding the gene transfer agent and the phage origin are well conserved in Bartonella, we hypothesize that these systems are driven by selection. We propose that the coupling of run-off replication with gene transfer agents promotes diversification and rapid spread of host-adaptability factors, facilitating host shifts in Bartonella.
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| 6. |
- Dyrhage, Karl, et al.
(författare)
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Genome Evolution of a Symbiont Population for Pathogen Defence in Honeybees
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Ingår i: Genome Biology and Evolution. - 1759-6653.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The honeybee gut microbiome is thought to be important for bee health, but the role of the individual members is poorly understood. Here, we present closed genomes and associated mobilomes of 102 Apilactobacillus kunkeei isolates obtained from the honey crop (foregut) of honeybees sampled from beehives in Helsingborg in the south of Sweden and from the islands Gotland and Åland in the Baltic Sea. Each beehive contained a unique composition of isolates and repeated sampling of similar isolates from two beehives in Helsingborg suggests that the bacterial community is stably maintained across bee generations during the summer months. The sampled bacterial population contained an open pan- genome structure with a high genomic density of transposons. A subset of strains affiliated with phylogroup A inhibited growth of the bee pathogen Melisococcus plutonius, all of which contained a 19.5 kb plasmid for the synthesis of the antimicrobial compound kunkecin A, while a subset of phylogroups B and C strains contained a 32.9 kb plasmid for the synthesis of a putative polyketide antibiotic. This study suggests that the mobile gene pool of A. kunkeei plays a key role in pathogen defence in honeybees, providing new insights into the evolutionary dynamics of defensive symbiont populations.
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| 7. |
- Dyrhage, Karl, et al.
(författare)
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Genome Evolution of a Symbiont Population for Pathogen Defense in Honeybees
- 2022
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Ingår i: Genome Biology and Evolution. - : Oxford University Press (OUP). - 1759-6653. ; 14:11
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Tidskriftsartikel (refereegranskat)abstract
- The honeybee gut microbiome is thought to be important for bee health, but the role of the individual members is poorly understood. Here, we present closed genomes and associated mobilomes of 102 Apilactobacillus kunkeei isolates obtained from the honey crop (foregut) of honeybees sampled from beehives in Helsingborg in the south of Sweden and from the islands Gotland and angstrom land in the Baltic Sea. Each beehive contained a unique composition of isolates and repeated sampling of similar isolates from two beehives in Helsingborg suggests that the bacterial community is stably maintained across bee generations during the summer months. The sampled bacterial population contained an open pan-genome structure with a high genomic density of transposons. A subset of strains affiliated with phylogroup A inhibited growth of the bee pathogen Melissococcus plutonius, all of which contained a 19.5 kb plasmid for the synthesis of the antimicrobial compound kunkecin A, while a subset of phylogroups B and C strains contained a 32.9 kb plasmid for the synthesis of a putative polyketide antibiotic. This study suggests that the mobile gene pool of A. kunkeei plays a key role in pathogen defense in honeybees, providing new insights into the evolutionary dynamics of defensive symbiont populations.
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| 8. |
- Dyrhage, Karl, et al.
(författare)
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Mapping transcriptomics and proteomics data onto a metabolic pathway model of fructophilic lactic acid bacteria
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Fructophilic lactic acid bacteria have been isolated from fructose-rich habitats, such as fruits and fermented food derived from fruit products. Despite their unique biochemical characteristics, no studies of the expression patterns of enzymes involved in the fermentation of fructose have been performed. Here, we report a genome-wide study of expression profiles in Apilactobacillus kunkeei, an obligate fructophilic bacterium isolated from honeybees. Transcriptomics, proteomics and metabolomics data were collected from A. kunkeei strain A1401 at early exponential and early stationary growth in MRS medium supplemented with fructose and mapped onto a metabolic pathway model. The results confirmed high expression levels of enzymes involved in the fermentation of fructose to lactate and acetate during exponential growth. The transcription levels of genes for enzymes involved in the conversion of fructose to glucose-6-phosphate increased about 40-fold during the stationary phase. Likewise, the transcription levels of two operons for enzymes involved in de novo biosynthesis of UMP were upregulated about 30-fold during the shift to stationary phase. Moreover, genes coding for proteins involved in oxidative stress, protein degradation, heat shock and acid shock were highly upregulated during stationary growth. The results serve as an excellent basis for future genetic engineering efforts to exploit the unique biotechnological, ecological and dietary potential of Apilactobacillus kunkeei.
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| 9. |
- Ellegaard, Kirsten Maren, et al.
(författare)
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Comparative Genomics of Wolbachia and the Bacterial Species Concept
- 2013
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Ingår i: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 9:4, s. e1003381-
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Tidskriftsartikel (refereegranskat)abstract
- The importance of host-specialization to speciation processes in obligate host-associated bacteria is well known, as is also the ability of recombination to generate cohesion in bacterial populations. However, whether divergent strains of highly recombining intracellular bacteria, such as Wolbachia, can maintain their genetic distinctness when infecting the same host is not known. We first developed a protocol for the genome sequencing of uncultivable endosymbionts. Using this method, we have sequenced the complete genomes of the Wolbachia strains wHa and wNo, which occur as natural double infections in Drosophila simulans populations on the Seychelles and in New Caledonia. Taxonomically, wHa belong to supergroup A and wNo to supergroup B. A comparative genomics study including additional strains supported the supergroup classification scheme and revealed 24 and 33 group-specific genes, putatively involved in host-adaptation processes. Recombination frequencies were high for strains of the same supergroup despite different host-preference patterns, leading to genomic cohesion. The inferred recombination fragments for strains of different supergroups were of short sizes, and the genomes of the co-infecting Wolbachia strains wHa and wNo were not more similar to each other and did not share more genes than other A- and B-group strains that infect different hosts. We conclude that Wolbachia strains of supergroup A and B represent genetically distinct clades, and that strains of different supergroups can co-exist in the same arthropod host without converging into the same species. This suggests that the supergroups are irreversibly separated and that barriers other than host-specialization are able to maintain distinct clades in recombining endosymbiont populations. Acquiring a good knowledge of the barriers to genetic exchange in Wolbachia will advance our understanding of how endosymbiont communities are constructed from vertically and horizontally transmitted genes.
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