Towards a Wolbachia Multilocus Sequence Typing system : discrimination of Wolbachia strains present in Drosophila species

Author Posting. © The Author(s), 2006. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Current Microbiology 53 (2006): 388-395, doi:10.1007/s00284-006-0054-1.Among the diverse maternally inherited symbionts in arthropods, Wolbachia are the most common and infect over 20% of all species. In a departure from traditional genotyping or phylogenetic methods relying on single Wolbachia genes, the present study represents an initial Multilocus Sequence Typing (MLST) analysis to discriminate closely related Wolbachia pipientis strains, and additional data on sequence diversity in Wolbachia. We report new phylogenetic characterization of four genes (aspC, atpD, sucB and pdhB), and provide an expanded analysis of markers described in previous studies (16S rDNA, ftsZ, groEL, dnaA and gltA). MLST analysis of the bacterial strains present in sixteen different Drosophila-Wolbachia associations detected four distinct clonal complexes that also corresponded to maximum-likelihood identified phylogenetic clades. Among the sixteen associations analyzed, six could not be assigned to MLST clonal complexes and were also shown to be in conflict with relationships predicted by maximum-likelihood phylogenetic inferences. The results demonstrate the discriminatory power of MLST for identifying strains and clonal lineages of Wolbachia and provide a robust foundation for studying the ecology and evolution of this widespread endosymbiont.This work was partially supported by intramural funds of the University of Ioannina to K. Bourtzis, by grants to J.J. Wernegreen from the National Institutes of Health (R01 GM62626-01) and the NASA Astrobiology Institute (NNA04CC04A), and to J.H. Werren and J.J. Wernegreen from the National Science Foundation (EF-0328363)

Generation of Antigenic Variants via Gene Conversion: Evidence for Recombination Fitness Selection at the Locus Level in Anaplasma marginale

Multiple bacterial and protozoal pathogens utilize gene conversion to generate antigenically variant surface proteins to evade immune clearance and establish persistent infection. Both the donor alleles that encode the variants following recombination into an expression site and the donor loci themselves are under evolutionary selection: the alleles that encode variants that are sufficiently antigenically unique yet retain growth fitness and the loci that allow efficient recombination. We examined allelic usage in generating Anaplasma marginale variants during in vivo infection in the mammalian reservoir host and identified preferential usage of specific alleles in the absence of immune selective pressure, consistent with certain individual alleles having a fitness advantage for in vivo growth. In contrast, the loci themselves appear to have been essentially equally selected for donor function in gene conversion with no significant effect of locus position relative to the expression site or origin of replication. This pattern of preferential allelic usage but lack of locus effect was observed independently for Msp2 and Msp3 variants, both generated by gene conversion. Furthermore, there was no locus effect observed when a single locus contained both msp2 and msp3 alleles in a tail-to-tail orientation flanked by a repeat. These experimental results support the hypothesis that predominance of specific variants reflects in vivo fitness as determined by the encoding allele, independent of locus structure and chromosomal position. Identification of highly fit variants provides targets for vaccines that will prevent the high-level bacteremia associated with acute disease

The impact of high BMI on acute changes in body composition following 90 min of running

Objectives: Although physical activity ameliorates the metabolic impact of high body mass index (BMI), runners with BMI ≥25 kg/m2 are relatively understudied. This study had two goals: (1) to identify differences in body composition, as measured by dual X-ray absorptiometry (DXA), between overweight (BMI ≥ 25 kg/m2) runners (OWR) and normal weight (BMI < 25 kg/m2) runners (NWR) and (2) to examine whether a 90-min run alters total or regional fat mass, as measured by DXA, in OWR and NWR. We hypothesized that OWR would have higher total body fat than NWR and OWR with greater changes in visceral fat after a prolonged run. Design: Body composition analysis before and after a supervised run. Methods: We recruited NWR (n = 16, F: n = 7, 28.1 ± 1.4 years, BMI 22.0 ± 0.4 kg/m2, results as mean ± SE) and OWR (n = 11, F: n = 7, 32.0 ± 1.6 years, BMI 30.5 ± 1.4 kg/m2) participants. DXA-based body composition was measured before and after a supervised, 90-min run at 60% heart rate reserve. Results: OWR had higher body fat than NWR in all measured regions. Both groups did not significantly reduce fat mass at any measured fat depots after the running exposure. Conclusions: OWR had higher body fat in all measured regions than NWR. DXA could not demonstrate any acute fat mass changes after a prolonged run

The impact of high BMI on acute changes in body composition following 90 min of running

<p>Objectives: Although physical activity ameliorates the metabolic impact of high body mass index (BMI), runners with BMI ≥25 kg/m² are relatively understudied. This study had two goals: (1) to identify differences in body composition, as measured by dual X-ray absorptiometry (DXA), between overweight (BMI ≥ 25 kg/m²) runners (OWR) and normal weight (BMI < 25 kg/m²) runners (NWR) and (2) to examine whether a 90-min run alters total or regional fat mass, as measured by DXA, in OWR and NWR. We hypothesized that OWR would have higher total body fat than NWR and OWR with greater changes in visceral fat after a prolonged run. Design: Body composition analysis before and after a supervised run. Methods: We recruited NWR (<i>n</i> = 16, F: <i>n</i> = 7, 28.1 ± 1.4 years, BMI 22.0 ± 0.4 kg/m², results as mean ± SE) and OWR (<i>n</i> = 11, F: <i>n</i> = 7, 32.0 ± 1.6 years, BMI 30.5 ± 1.4 kg/m²) participants. DXA-based body composition was measured before and after a supervised, 90-min run at 60% heart rate reserve. Results: OWR had higher body fat than NWR in all measured regions. Both groups did not significantly reduce fat mass at any measured fat depots after the running exposure. Conclusions: OWR had higher body fat in all measured regions than NWR. DXA could not demonstrate any acute fat mass changes after a prolonged run.</p