Water availability modifies tolerance to photo-oxidative pollutants in transplants of the lichen Flavoparmelia caperata

The hypothesis that a daily water supply allows a lichen to endure the negative effects of environmental concentrations of NO_x and O₃ was tested with a transplant experiment. Five groups (0, A–D) of Flavoparmelia caperata samples derived from the same thalli were used for destructive, pre-exposure measurements (0), or exposed for 5 weeks in the rural collection site (A), and in a urban site with high levels of NO_x and O₃ (B–D). Two groups (C, D) were daily watered half an hour before the daily peak of NO_x (C), and O₃ (D). The comparison between pre- and post-exposure measurements of stress biomarkers revealed that the different thallus hydration regime modified the pollution tolerance as well as the physiology of the exposed samples. The non-watered group B suffered an evident decrease in F_v/F_m and reduced glutathione, but increased ion leakage, whereas the watered groups C and D showed only decreased non-photosynthetic-quenching, possibly derived from NO_x exposure. Ozone, which was higher in the rural than in the urban site, did not significantly affect the lichen metabolism. Our results re-open the discussion on the so-called “drought hypothesis”, which suggests that the lichen desert observed in urban areas of central and eastern Europe is more a matter of dry microclimate than of air pollution.     

Long-term decrease in VLA-4 expression and functional impairment of dendritic cells during natalizumab therapy in patients with multiple sclerosis

Myeloid and plasmacytoid dendritic cells (mDCs, pDCs) are central to the initiation and the regulation of immune processes in multiple sclerosis (MS). Natalizumab (NTZ) is a humanized monoclonal antibody approved for the treatment of MS that acts by blocking expression of VLA-4 integrins on the surface of leukocytes. We determined the proportions of circulating DC subsets and analyzed expression of VLA-4 expression in 6 relapsing-remitting MS patients treated with NTZ for 1 year. VLA-4 expression levels on pDCs and mDCs decreased significantly during follow-up. In vitro coculture of peripheral blood mononuclear cells and pDCs, with different doses of NTZ in healthy controls (HC) and MS patients showed dose-dependent down-regulation of VLA-4 expression levels in both MS patients and HC, and reduced functional ability to stimulate antigen-specific T-lymphocyte responses. The biological impact of NTZ may in part be attributable to inhibition of transmigration of circulating DCs into the central nervous system, but also to functional impairment of interactions between T cells and DC.     

CD14 deficiency impacts glucose homeostasis in mice through altered adrenal tone

The toll-like receptors comprise one of the most conserved components of the innate immune system, signaling the presence of molecules of microbial origin. It has been proposed that signaling through TLR4, which requires CD14 to recognize bacterial lipopolysaccharide (LPS), may generate low-grade inflammation and thereby affect insulin sensitivity and glucose metabolism. To examine the long-term influence of partial innate immune signaling disruption on glucose homeostasis, we analyzed knockout mice deficient in CD14 backcrossed into the diabetes-prone C57BL6 background at 6 or 12 months of age. CD14-ko mice, fed either normal or high-fat diets, displayed significant glucose intolerance compared to wild type controls. They also displayed elevated norepinephrine urinary excretion and increased adrenal medullary volume, as well as an enhanced norepinephrine secretory response to insulin-induced hypoglycemia. These results point out a previously unappreciated crosstalk between innate immune- and sympathoadrenal- systems, which exerts a major long-term effect on glucose homeostasis.     

1H, 15N and 13C chemical shift assignments of the BA42 protein of the psychrophilic bacteria Bizionia argentinensis sp. nov

BA42 is a protein belonging to the psychrophilic bacteria Bizionia argentinensis sp. nov. Bioinformatics analysis showed that it presents significant sequence identity with a Pfam A family, DUF 477, found both in eukarya and eubacteria but of unknown function in all these organisms. Here, we report the NMR spectra assignment of this 145 amino acid protein. These data will allow performing NMR structural studies with the aim of using the three-dimensional structure as relevant information in order to determine the function of this family of proteins.     

2D-DIGE analysis of mango (Mangifera indica L.) fruit reveals major proteomic changes associated with ripening

A comparative proteomic investigation between the pre-climacteric and climacteric mango fruits (cv. Keitt) was performed to identify protein species with variable abundance during ripening. Proteins were phenol-extracted from fruits, cyanine-dye-labeled, and separated on 2D gels at pH 4-7. Total spot count of about 373 proteins spots was detected in each gel and forty-seven were consistently different between pre-climacteric and climacteric fruits and were subjected to LC-MS/MS analysis. Functional classification revealed that protein species involved in carbon fixation and hormone biosynthesis decreased during ripening, whereas those related to catabolism and the stress-response, including oxidative stress and abiotic and pathogen defense factors, accumulated. In relation to fruit quality, protein species putatively involved in color development and pulp softening were also identified. This study on mango proteomics provides an overview of the biological processes that occur during ripening.     

Phenotypic and histochemical traits of the interaction between Plasmopara viticola and resistant or susceptible grapevine varieties

ABSTRACT: BACKGROUND: Grapevine downy mildew, caused by Plasmopara viticola, is a very serious disease affectingmainly Vitis vinifera cultivated varieties around the world. Breeding for resistance throughthe crossing with less susceptible species is one of the possible means to reduce the diseaseincidence and the application of fungicides. The hybrid Bianca and some of its siblings areconsidered very promising but their resistance level can vary depending on the pathogenstrain. Moreover, virulent strains characterized by high fitness can represent a potential threatto the hybrid cultivation. RESULTS: The host response and the pathogen virulence were quantitatively assessed by artificiallyinoculating cv Chardonnay, cv Bianca and their siblings with P. viticola isolates derived fromsingle germinating oospores collected in various Italian viticultural areas. The hostphenotypes were classified as susceptible, intermediate and resistant, according to the AreaUnder the Disease Progress Curve caused by the inoculated strain. Host responses in cvBianca and its siblings significantly varied depending on the P. viticola isolates, which in turndiffered in their virulence levels. The fitness of the most virulent strain did not significantlyvary on the different hybrids including Bianca in comparison with the susceptible cvChardonnay, suggesting that no costs are associated with virulence. Among the individualfitness components, only sporangia production was significantly reduced in cv Bianca and insome hybrids. Comparative histological analysis revealed differences between susceptibleand resistant plants in the pathogen diffusion and cytology from 48 h after inoculation onwards. Defence mechanisms included callose depositions in the infected stomata, increasein peroxidase activity, synthesis of phenolic compounds and flavonoids and the necrosis ofstomata and cells immediately surrounding the point of invasion and determined alterations inthe size of the infected areas and in the number of sporangia differentiated. CONCLUSIONS: Some hybrids were able to maintain an intermediate-resistant behaviour even wheninoculated with the most virulent strain. Such hybrids should be considered for further fieldtrials.     

Assembly and mechanisms of bacterial type IV secretion machines

Type IV secretion occurs across a wide range of prokaryotic cell envelopes: Gram-negative, Gram-positive, cell wall-less bacteria and some archaea. This diversity is reflected in the heterogeneity of components that constitute the secretion machines. Macromolecules are secreted in an ATP-dependent process using an envelope-spanning multi-protein channel. Similar to the type III systems, this apparatus extends beyond the cell surface as a pilus structure important for direct contact and penetration of the recipient cell surface. Type IV systems are remarkably versatile in that they mobilize a broad range of substrates, including single proteins, protein complexes, DNA and nucleoprotein complexes, across the cell envelope. These machines have broad clinical significance not only for delivering bacterial toxins or effector proteins directly into targeted host cells, but also for direct involvement in phenomena such as biofilm formation and the rapid horizontal spread of antibiotic resistance genes among the microbial community.     

Effects of ultraviolet radiation and nutrients on the structure-function of phytoplankton in a high mountain lake

The combined effect of high solar ultraviolet radiation (UVR) and nutrient supply in a phytoplankton community of a high mountain lake is analyzed in a in situ experiment for 6 days with 2 × 2 factorial design. Interactive UVR × nutrient effects on structural and functional variables (algal biomass, chlorophyll a (chl a), primary production (PP), maximal electron transport rate (ETR(max)), and alkaline phosphatase activity (APA)), as well as stoichiometric ones (sestonic N per cell and N:P ratio) were found. Under non-nutrient enriched conditions, no deleterious effects of UVR on structural variables, PP, photosynthetic efficiency and ETR(max) were observed, whereas only particulate and total APA were affected by UVR. However, percentage excreted organic carbon (%EOC), dissolved APA and sestonic C and P per cell increased under UVR, leading to a decrease in algal C:P and N:P ratios. After nutrient enrichment, chl a, total algal biomass and PP were negatively affected by UVR whereas %EOC, ETR(max) and internal C, P and N content increased. We suggest that the mechanism of algal acclimation to UVR in this high UVR flux ecosystem seems to be related to the increase of internal algal P-content mediated by physiological mechanisms to save P and by a stimulatory UVR effect on dissolved extracellular APA. The mechanism involved in the unmasking effect of UVR after nutrient-enrichment may be the result of a greater sensitivity to UVR-induced cell damage, making the negative UVR effects more evident.     

Uncommon acquired Gerbode defect following extensive bicuspid aortic valve endocarditis

Gerbode defect is a rare type of left ventricle to right atrium shunt. It is usually congenital in origin, but acquired cases are also described, mainly following infective endocarditis, valve replacement, trauma or acute myocardial infarction. We report a case of a 50-year-old man who suffered an extensive and complex infective endocarditis involving a bicuspid aortic valve, the mitral-aortic intervalvular fibrosa and the anterior leaflet of the mitral valve. After dual valve replacement and annular reconstruction, a shunt between the left ventricle and the right atrium - Gerbode defect, and a severe leak of the mitral prosthesis were detected. Reintervention was performed with successful shunt closure with an autologous pericardial patch and paravalvular leak correction. No major complications occurred denying the immediate post-surgery period and the follow-up at the first year was uneventful.