Tissue transglutaminase in celiac disease: role of autoantibodies

In celiac disease (CD), gluten, the disease-inducing toxic component in wheat, induces the secretion of IgA-class autoantibodies which target tissue transglutaminase (tTG). These autoantibodies are produced in the small-intestinal mucosa, and, during gluten consumption, they can also be detected in patients' serum but disappear slowly from the circulation on a gluten-free diet. Interestingly, after adoption of a gluten-free diet the serum autoantibodies disappear from the circulation more rapidly than the small-intestinal mucosal autoantibody deposits. The finding of IgA deposits on extracellular tTG in the liver, kidney, lymph nodes and muscles of patients with CD indicates that tTG is accessible to the gut-derived autoantibodies. Although the specific autoantibody response directed against tTG is very characteristic in celiac patients, their role in the immunopathology of the celiac mucosal lesion is a matter of debate. Here we report a brief summary of anti-tTG antibody effects demonstrating that these antibodies are functional and not mere bystanders in the disease pathogenesis. In fact, they inhibit intestinal epithelial cell differentiation, induce intestinal epithelial cell proliferation, increase epithelial permeability and activate monocytes and disturb angiogenesis.     

Ants in their plants: Pseudomyrmex ants reduce primate,parrot and squirrel predation on Macrolobium acaciifolium (Fabaceae) seeds in Amazonian Brazil

Although plant‐inhabiting ants are known to act as effective deterrents to a variety of vertebrate and invertebrate herbivores, this has been reported only once before for primates, a group better known for their predation of ants. In the present study, we investigated the effects that colonies of Pseudomyrmex viduus ants living in individual Macrolobium acaciifolium (Fabaceae) trees have on the rates of visitation and fruit removal by four taxa of seed‐predating vertebrates: the primate Cacajao melanocephalus ouakary; macaws (Ara spp.); large parrots (Amazona spp.); and the Northern Amazonian red squirrel (Sciurus igniventris). We found that ant presence significantly reduced both rates of visitation and of fruit removal by C. m. ouakary. The same pattern of reduced fruit removal was also observed for other seed predators (parrots, macaws, and squirrels) but not for visitation rates (although this may be a result of the small sample size). This appears to be only the second‐known demonstration of the repellent effect of ants on primates and, indeed, the first for squirrels and psittacine birds. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 260–273.     

Development of a strain-specific genomic marker for monitoring a Bacillus subtilis biocontrol strain in the rhizosphere of tomato

A strain-specific molecular marker enabling the detection and tracking of the biological control agent Bacillus subtilis 101, when released into the environment, was developed. Random amplified polymorphic DNA (RAPD) technique was used to differentiate this from other B. subtilis strains. A differentially amplified fragment obtained from RAPD profiles was sequenced and characterized as sequence-characterized amplified region (SCAR) marker, and four primer pairs were designed and evaluated for their specificity towards this strain. The sensibility of the selected SCAR primer pair was evaluated by qualitative PCR and Southern blotting, and the detection limit was assessed around 10(2) CFU (g dry wt soil)(-1), thus providing a reliable tool for the traceability of this B. subtilis strain in greenhouse or field trials. A plating assay coupled to PCR with the SCAR primer pair was then used as a detection method in microcosm experiments for monitoring the population of B. subtilis 101 in the rhizosphere of tomato, grown under two different soil conditions, i.e. nonsterile peat-based substrate and sandy-loam agricultural soil, respectively. The data of rhizosphere colonization indicated that the soil conditions significantly affected the rhizosphere establishment of strain 101.     

Prognostic factors and predictors of outcome in patients with COVID-19 and related pneumonia: a retrospective cohort study

The aim of the present study was to simultaneously assess several potential predictors of outcome (co-morbidity, previous and in-hospital treatment, radiologic Brixia score) in patients with COVID-19.This retrospective cohort study included 258 consecutive patients with confirmed COVID-19 admitted to a medical ward at Montichiari Hospital, Brescia, Italy from February 28th to April 30rd, 2020. Patients had SARS-CoV-2 related pneumonia with respiratory failure, and were treated with hydroxychloroquine and lopinavir plus ritonavir. In some patients, additional treatment with tocilizumab, dexamethasone and enoxaparin was adopted. Outcomes (death or recovery) were assessed at the end of the discharge period or at the end of the follow-up (August 2020).During hospitalization, 59 patients died, while 6 died after discharge. The following variables were demonstrated to be associated with a worse prognosis: Radiologic Brixia score higher than 8, presence at baseline of hypertension, diabetes, chronic obstructive pulmonary disease, heart disease, cancer, previous treatment with ACE-inhibitors or anti-platelet drugs. Anticoagulant treatment during hospital admission with enoxaparin at a dose higher than 4000 U once daily was associated with a better prognosis.In conclusion, our study demonstrates that some co-morbidities and cardiovascular risk factors may affect prognosis. The radiologic Brixia score may be a useful tool to stratify the risk of death at baseline. Anticoagulant treatment with enoxaparin might be associated to a clinical benefit in terms of survival in patients with COVID-19.     

Glutamate synthesis in barley roots: the role of the plastidic glucose-6-phosphate dehydrogenase

Evidence is provided for a close link between glutamate (Glu) synthesis and the production of reducing power by the oxidative pentose phosphate pathway (OPPP) in barley ( Hordeum vulgare L. var. Alfeo) root plastids. A rapid procedure for isolating organelles gave yields of plastids of over 30%, 60% of which were intact. The formation of Glu by intact plastids fed with glutamine and 2-oxoglutarate, both substrates of glutamate synthase (GOGAT), depends on glucose-6-phosphate (Glc-6-P) supply. The whole process exhibited an apparent K(m Glc-6-P) of 0.45 mM and is abolished by azaserine, a specific inhibitor of GOGAT; ATP caused a decrease in the rate of Glu formation. Glucose and other sugar phosphates were not as effective in supporting Glu synthesis with respect to Glc-6-P; only ribose-5-phosphate, an intermediate of OPPP, supported rates equivalent to Glc-6-P. Glucose-6-phosphate dehydrogenase (Glc6PDH) rapidly purified from root plastids showed an apparent K(m Glc-6-P) of 0.96 mM and an apparent K(m NADP)(+) of 9 micro M. The enzyme demonstrated high tolerance to NADPH, exhibiting a K(i) (NADPH) of 58.6 micro M and selectively reacted with antibodies against potato plastidic, but not chloroplastic, Glc6PDH isoform. The data support the hypothesis that plastidic OPPP is the main site of reducing power supply for GOGAT within the plastids, and suggest that the plastidic OPPP would be able to sustain Glu synthesis under high NADPH:NADP(+) ratios even if the plastidic Glc6PDH may not be functioning at its highest rates.     

Interaction between gfp-tagged Pseudomonas tolaasii P12 and Pleurotus eryngii

Pseudomonas sp., (formerly reported as strain P12) which produces brown blotch disease symptoms on Pleurotus eryngii, has been identified as P. tolaasii based on its biochemical, physiological properties and 16S rDNA sequence analysis. This pathogen is able to infect basidiocarps when surface-inoculated on mushroom casing soil. However, infected basidiocarps develop the brown blotch disease symptoms when the pathogen concentration in the fruiting body tissues is higher than 10(4) cfu/g d.w. Using gfp-tagged cells and confocal laser scanning microscopy, it was possible to show that the pathogen has the ability to tightly attach to the hyphae of Pleurotus eryngii.