Genome dynamics of Bartonella grahamii in micro-populations of woodland rodents

<p>Abstract</p> <p>Background</p> <p>Rodents represent a high-risk reservoir for the emergence of new human pathogens. The recent completion of the 2.3 Mb genome of <it>Bartonella grahamii</it>, 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 <it>B. grahamii </it>population was recently investigated by multi locus sequence typing, but no study on the variability of putative host-cell interaction systems has been performed.</p> <p>Results</p> <p>To study the population dynamics of <it>B. grahamii</it>, we analyzed the genomic diversity on a whole-genome scale of 27 <it>B. grahamii </it>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 <it>fha </it>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 <it>fha </it>gene or the plasmid.</p> <p>Conclusion</p> <p>Our study has revealed a geographic microstructure of <it>B. grahamii </it>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.</p

Retained NK cell phenotype and functionality in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), and the progressive stage non-alcoholic steatohepatitis (NASH), is the predominant cause of chronic liver disease globally. As part of the complex pathogenesis, natural killer (NK) cells have been implicated in the development of liver inflammation in experimental murine models of NASH. However, there is a lack of knowledge on how NK cells are affected in humans with this disease. Here, we explored the presence of disease-specific changes within circulating and tissue-resident NK cell populations, as well as within other major immune cell subsets, in patients with liver biopsy-confirmed NAFLD. Using 18-color-flow cytometry, substantial changes were observed in certain myeloid populations in patients as compared to controls. NK cell numbers, on the other hand, were not altered. Furthermore, only minor differences in expression of activating and inhibitory NK cell receptors were noted, with the exception of an increased expression of NKG2D on NK cells from patients with NASH. NK cell differentiation remained constant, and NK cells from these patients retain their ability to respond adequately upon stimulation. Instead, considerable alterations were observed between liver, adipose tissue, and peripheral blood NK cells, independently of disease status. Taken together, these results increase our understanding of the importance of the local microenvironment in shaping the NK cell compartment and stress the need for further studies exploring how NASH affects intrahepatic NK cells in humans.publishedVersio

Implementing storm damage in a dynamic vegetation model for regional applications in Sweden

Wind is the dominant agent of damage in forests in Western Europe. Traditional winddamage models calculate a probability for damage or a critical wind speed at which damage occurs. However, in a dynamic vegetation model actual damage to stands and individual trees is needed to get a dynamical progression of the vegetation. We present a prototype for a new approach to modelling forest wind damage at the regional scale, which we incorporate within a dynamic vegetation model. The approach is based on knowledge from both empirical and mechanical models and calculates the damaged fraction of a cohort based on wind load and a sensitivity that depends on the current physical state and history of the cohort in relation to the ecosystem. The modelling concept has been developed, calibrated and evaluated for Swedish conditions but can be applicable to other similar areas with minor modification. Because of the stochastic nature of local wind load and the difficulty of describing the stand-level exposure, the ability to explain observed damage at stand level was low. Regional level variation in damage, which more depends on the wind load, was however explained reasonably well (R2 = 0.43). We suggest that this is a useful concept for evaluating alternatives of forest management under different climate scenarios in the process of adaptation to future storm-damage risks

Run-Off Replication of Host-Adaptability Genes Is Associated with Gene Transfer Agents in the Genome of Mouse-Infecting Bartonella grahamii

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

Studies on determinants for health behavior and the relationships between behavior, beliefs,and knowledge

Näslund, Görel K. Health behavior - studies on determinants for healthbehavior and the relationships between health behavior, beliefs, andknowledge. Karolinska Institute, Department of Clinical Neuroscience, KarolinskaHospital, Stockholm, Sweden.The general aim was to study determinants for health behavior. The groups surveyedwere 1) male and female university students, 2) male and female blue-collar workers, and3) middle-aged men with slightly to moderately elevated coronary heart disease riskfactors invited to participate in a 6-month diet and physical exercise program. Theresearch also surveyed the relationships between health behavior, beliefs and knowledge,and the role of demographic, socioeconomic, and personality factors for health behaviorand compliance with medical care recommendations. Both among university students and blue-collar workers, women werecharacterized by having more positive health practices, better health knowledge, andstronger beliefs about the importance of positive health practices than men. A relationshipwas found between behavior and beliefs concerning the importance of positive healthpractices, and between knowledge and beliefs, while the link between health knowledgeand behavior was weak. Middle-aged men who enrolled, and who declined to enrol, in a 6-month diet andphysical exercise program were characterized by different health beliefs and knowledge.Among the participants in the diet and exercise intervention program, reduced compliancewith increased intake of dietary fiber was linked to smoking, higher levels of hostility,perception of barriers to dietary change, and poor knowledge of CHD risk factors.Reduced compliance with low fat diet was linked to smoking, younger age, and nothaving relatives or friends afflicted with CHD. Reduced compliance with the physicalexercise program tended to be associated with younger age and having children living athome. Both smokers and non-smokers managed to reduce their estimated CHD risk inthe intervention program, but after intervention the smokers still had an elevated coronaryrisk profile compared to non-smokers. Despite similar knowledge about the healthhazards of smoking, smokers gave a lower rating than non-smokers for the importance ofnot smoking. It was concluded that although health behaviors may be determined by anumber of different factors, behaviors are generally linked to beliefs about the importanceof positive health practices.Key words: health behavior, health beliefs, health knowledge, complianceISBN 91-628-1849-

Förutsättningar för att bedriva diabetesvård i Tanzania. : En kvalitativ intervjustudie.

Syftet med denna studie var att beskriva vilken uppfattning sjuksköterskor i Tanzania har om förutsättningarna för att bedriva diabetesvård. Studien genomfördes som en beskrivande kvalitativ intervjustudie. Ett icke-slumpmässigt strategiskt urval gjordes och fem sjuksköterskor deltog. Data samlades in genom semistrukturerade intervjuer och en manifest innehållsanalys gjordes på intervjutexterna. Resultatet visar på en ekonomisk situation med få resurser och tillgångar. Sjuksköterskorna är få och patienterna är många vilket gör att utbildningen och informationsbehovet hos patienterna inte alltid kan mötas. På sjukhuset finns det för lite blodsockermätare och det händer att det inte finns något insulin att tillgå. Den ekonomiska situationen för patienterna gör att de har svårt att få någon kontinuitet i både behandling och kontroller. Insulin är dyrt och alla har inte råd med det. De flesta har ingen blodsockermätare utan kontrollerar sitt blodsocker på klinik, vilket även det kostar pengar. Många har heller inte råd med en fullgod kost. Den ekonomiska situationen både för patienter och sjukvården gör diabetesvården svår

Born to be wild: effects of rearing density and environmental enrichment on stress, welfare and smolt migration in hatchery reared Atlantic salmon

Hatchery reared salmonids released into the wild generally have poor survivability compared to wild conspecifics. In order to assess potential hatchery rearing improvements, behavioral and physiological effects of reducing animal density and adding in-tank shelter were investigated. Atlantic salmon parr were placed in barren or shelter enriched tanks at high or low density up until release as smolts. A lowered density rendered positive effects on growth and intestinal barrier function and the combination of a lower density and shelter decreased conspecific aggression, as inferred by fin damage. Furthermore, while the presence of shelter decreased stress hormone levels following human disturbance it also decreased growth and smolt migration success, an effect particularly pronounced at high densities. Therefore, we suggest that this type of structural enrichment should be avoided for Atlantic salmon smolts held at high densities and conclude that a lowered animal density with or without shelter has the highest potential in producing a more resilient smolt for stocking.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Supplementary information for manuscript "<i>Apilactobacillus kunkeei</i><i> </i><i>releases RNA-associated membrane vesicles and proteinaceous nanoparticles</i>"

Supplementary information for manuscript "Apilactobacillus kunkeei releases RNA-associated membrane vesicles and proteinaceous nanoparticles".The supplementary information comprises imaging data obtained from Transmission (TEM) and Scanning Electron Microscopy (SEM) as well as negative stain TEM (nsTEM). Electron micrographs have been obtained from whole cells of two Apilactobacillus kunkeei strains, A0901 and A1401, by TEM and SEM, as well as from isolated secreted nanoparticles (nSTEM). Those particles have been described as membranous RNA-associated membrane vesicles (MVs) and proteinaceous extracellular particles (ECPs).The compressed folder contains the imaging files. Files and subdirectories are described in manifest.txt. The imaging folder contains a file, file.description.ecp.imaging.xlsx, with metainformation on the collected electron microscopy images.</p

Comparative Genomics of Wolbachia and the Bacterial Species Concept

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