Complete Genome Sequence of a Variant of Campylobacter jejuni NCTC 11168

Campylobacter jejuni NCTC 11168 is widely used in research, but at least two variants have been reported. The available genome was sequenced from a variant which later showed a different phenotype and gene expression profile. Here we present the complete genome sequence of a second variant of C. jejuni NCTC 11168.     

Rodaucea, a new genus of the Laboulbeniales

The new genus Rodaucea is created for a new species of Laboulbeniales parasitic on carrion beetles from Ecuador. The new genus is characterized by the presence of two unequal secondary receptacles flanking cell II on opposite sides. The perithecia have the wall cells arranged in four tiers distinctly unequal in height and the antheridia are phialid-like structures borne terminally on branches of primary and secondary appendages.     

Fabs enable single particle cryoEM studies of small proteins

In spite of its recent achievements, the technique of single particle electron cryomicroscopy (cryoEM) has not been widely used to study proteins smaller than 100 kDa, although it is a highly desirable application of this technique. One fundamental limitation is that images of small proteins embedded in vitreous ice do not contain adequate features for accurate image alignment. We describe a general strategy to overcome this limitation by selecting a fragment antigen binding (Fab) to form a stable and rigid complex with a target protein, thus providing a defined feature for accurate image alignment. Using this approach, we determined a three-dimensional structure of an ～65 kDa protein by single particle cryoEM. Because Fabs can be readily generated against a wide range of proteins by phage display, this approach is generally applicable to study many small proteins by single particle cryoEM.     

Identification of an active dimeric intermediate populated during the unfolding process of the cambialistic superoxide dismutase from Streptococcus mutans

Superoxide dismutases are enzymes that protect biological systems against oxidative damage caused by superoxide radicals. In this paper, a detailed characterization is presented on the stability of SmSOD, the dimeric cambialistic superoxide dismutase from the dental pathogenic microorganism Streptococcus mutans, towards temperature and guanidine hydrochloride. Thermal and chemical denaturations were investigated by means of circular dichroism, fourth-derivative UV spectroscopy and fluorescence measurements. Data indicate that SmSOD is endowed with a significant thermostability and that both its thermal and guanidine hydrochloride-induced unfolding processes occur through a three-state model, characterized by a catalytically active dimeric intermediate species. To our knowledge, SmSOD is the smallest known dimeric protein that populates a well-structured active dimeric rather than a monomeric intermediate during unfolding processes.     

Effect of D-alanine in teichoic acid from the Streptococcus thermophilus cell wall on the barrier-protection of intestinal epithelial cells

D-Alanylation of teichoic acid (TA) affects various functions of Gram-positive bacteria, including immunomodulatory effects. We investigated in this study the impact of D-alanine (D-Ala) in TA from Streptococcus thermophilus ATCC 19258(T) on the barrier-protecting effect in human intestinal Caco-2 cells. ATCC 19258(T) suppressed the tumor necrosis factor-α-induced decrease in transepithelial electrical resistance (TER), an indicator of the barrier function. The D-alanylation of TA in ATCC 19258(T) was growth phase- and culture temperature-dependent. Treatment of ATCC 19258(T) with Mg(2+) decreased the dlt mRNA expression and D-Ala content in TA and also abolished the suppressive effect on the TER decrease. Supplementation with L-alanine (L-Ala) to the broth led to an increase of D-Ala in ATCC 19258(T) and of the intestinal barrier-protecting effect. Taken together, D-Ala in TA played an important role in the barrier-protecting effect of S. thermophilus in the intestinal epithelium, and these beneficial effects could be enhanced by exogenous L-Ala.     

Collagen plays an active role in the aggregation of beta2-microglobulin under physiopathological conditions of dialysis-related amyloidosis

Dialysis-related amyloidosis is characterized by the deposition of insoluble fibrils of beta(2)-microglobulin (beta(2)-m) in the musculoskeletal system. Atomic force microscopy inspection of ex vivo amyloid material reveals the presence of bundles of fibrils often associated to collagen fibrils. Aggregation experiments were undertaken in vitro with the aim of reproducing the physiopathological fibrillation process. To this purpose, atomic force microscopy, fluorescence techniques, and NMR were employed. We found that in temperature and pH conditions similar to those occurring in periarticular tissues in the presence of flogistic processes, beta(2)-m fibrillogenesis takes place in the presence of fibrillar collagen, whereas no fibrils are obtained without collagen. Moreover, the morphology of beta(2)-m fibrils obtained in vitro in the presence of collagen is extremely similar to that observed in the ex vivo sample. This result indicates that collagen plays a crucial role in beta(2)-m amyloid deposition under physiopathological conditions and suggests an explanation for the strict specificity of dialysis-related amyloidosis for the tissues of the skeletal system. We hypothesize that positively charged regions along the collagen fiber could play a direct role in beta(2)-m fibrillogenesis. This hypothesis is sustained by aggregation experiments performed by replacing collagen with a poly-L-lysine-coated mica surface. As shown by NMR measurements, no similar process occurs when poly-L-lysine is dissolved in solution with beta(2)-m. Overall, the findings are consistent with the estimates resulting from a simplified collagen model whereby electrostatic effects can lead to high local concentrations of oppositely charged species, such as beta(2)-m, that decay on moving away from the fiber surface.     

IL-18 bridges innate and adaptive immunity through IFN-gamma and the CD134 pathway

IL-18 induces inflammation resulting in either enhanced protection from pathogens or exacerbation of autoimmunity, and T cells are profoundly activated during these responses. How IL-18 influences T cell activation is unknown, but this study in mice shows that IL-18 boosted Ag-specific T cell clonal expansion of effector T cells and induced a subpopulation of IFN-gamma superproducing T cells. Commitment to IFN-gamma production through IL-18 was independent of NK cells and IL-12 but dependent on host-derived IFN-gamma. To determine how expansion of these effectors occurred, IL-18 was shown to induce OX40L on dendritic cells, whereas peptide stimulation induced CD134 (OX40) on specific T cells. CD134 blockade inhibited T cell effector expansion thereby reducing the number of IFN-gamma superproducers by 12-fold. Thus, independent of IL-12, IL-18 impacts T cell immunity throughout lymphoid and nonlymphoid tissue by bridging the innate and adaptive arms of the immune system through IFN-gamma and the CD134 costimulatory pathway.     

Metabolic response to exogenous ethanol in yeast: an in vivo NMR and mathematical modelling approach

The understanding of the metabolic behaviour of complex systems such as eukaryotic cells needs the development of new approaches that are able to deal with the complexity due to a large number of interactions within the system. In this paper, we applied an approach based on the combined use of in vivo NMR experiments and mathematical modelling in order to analyze the metabolic response to ethanol stress in a wild-strain of Saccharomyces cerevisiae. Considering the cellular metabolic processes resulting from activation, inhibition, and feed-back activities, we developed a model able to describe the modulation of the whole system induced by an external stress due to increasing concentrations of exogenous ethanol. This approach was able to interpret the experimental results in terms of metabolic response to exogenous ethanol in the yeast. The robustness and flexibility of the model enables it to work correctly at different initial exogenous ethanol concentrations.     

Aspergillosis in Larus cachinnans micaellis: Survey of Eight Cases

Avian aspergillosis is reported in several avian species, with Aspergillus fumigatus as the main aetiological agent. Predisposing factors such as starvation, thermal stress, migratory stress, primary infectious disease or toxicosis may play a role. Eight cases of disseminated aspergillosis in free ranging seagulls sheltered at C.R.U.M.A. (Centro Recupero Uccelli Marini e Acquatici, Livorno, Italy) with different clinical histories are presented. The infection was demonstrated by cultural and histological methods from lesions of all birds, and the presence of airborne A. fumigatus viable elements ranging from 450 to 525 CFU/m³ inside and outside the shelter by means of a surface air sampler (SAS) Super-90 was also assessed. The role of this fungal species as an opportunistic factor in the captivity of seagulls is considered and some control measures, such as a clean and stress free environment and the use of antifungal drugs are suggested.