Rate of warming affects temperature sensitivity of anaerobic peat decomposition and greenhouse gas production

Temperature sensitivity of anaerobic carbon mineralization in wetlands remains poorly represented in most climate models and is especially unconstrained for warmer subtropical and tropical systems which account for a large proportion of global methane emissions. Several studies of experimental warming have documented thermal acclimation of soil respiration involving adjustments in microbial physiology or carbon use efficiency (CUE), with an initial decline in CUE with warming followed by a partial recovery in CUE at a later stage. The variable CUE implies that the rate of warming may impact microbial acclimation and the rate of carbon‐dioxide (CO₂) and methane (CH₄) production. Here, we assessed the effects of warming rate on the decomposition of subtropical peats, by applying either a large single‐step (10°C within a day) or a slow ramping (0.1°C/day for 100 days) temperature increase. The extent of thermal acclimation was tested by monitoring CO₂ and CH₄ production, CUE, and microbial biomass. Total gaseous C loss, CUE, and MBC were greater in the slow (ramp) warming treatment. However, greater values of CH₄–C:CO₂–C ratios lead to a greater global warming potential in the fast (step) warming treatment. The effect of gradual warming on decomposition was more pronounced in recalcitrant and nutrient‐limited soils. Stable carbon isotopes of CH₄ and CO₂ further indicated the possibility of different carbon processing pathways under the contrasting warming rates. Different responses in fast vs. slow warming treatment combined with different endpoints may indicate alternate pathways with long‐term consequences. Incorporations of experimental results into organic matter decomposition models suggest that parameter uncertainties in CUE and CH₄–C:CO₂–C ratios have a larger impact on long‐term soil organic carbon and global warming potential than uncertainty in model structure, and shows that particular rates of warming are central to understand the response of wetland soils to global climate change.     

FLT3 Mutations in Early T-Cell Precursor ALL Characterize a Stem Cell Like Leukemia and Imply the Clinical Use of Tyrosine Kinase Inhibitors

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) has been identified as high-risk subgroup of acute T-lymphoblastic leukemia (T-ALL) with a high rate of FLT3-mutations in adults. To unravel the underlying pathomechanisms and the clinical course we assessed molecular alterations and clinical characteristics in a large cohort of ETP-ALL (n = 68) in comparison to non-ETP T-ALL adult patients. Interestingly, we found a high rate of FLT3-mutations in ETP-ALL samples (n = 24, 35%). Furthermore, FLT3 mutated ETP-ALL was characterized by a specific immunophenotype (CD2+/CD5-/CD13+/CD33-), a distinct gene expression pattern (aberrant expression of IGFBP7, WT1, GATA3) and mutational status (absence of NOTCH1 mutations and a low frequency, 21%, of clonal TCR rearrangements). The observed low GATA3 expression and high WT1 expression in combination with lack of NOTCH1 mutations and a low rate of TCR rearrangements point to a leukemic transformation at the pluripotent prothymocyte stage in FLT3 mutated ETP-ALL. The clinical outcome in ETP-ALL patients was poor, but encouraging in those patients with allogeneic stem cell transplantation (3-year OS: 74%). To further explore the efficacy of targeted therapies, we demonstrate that T-ALL cell lines transfected with FLT3 expression constructs were particularly sensitive to tyrosine kinase inhibitors. In conclusion, FLT3 mutated ETP-ALL defines a molecular distinct stem cell like leukemic subtype. These data warrant clinical studies with the implementation of FLT3 inhibitors in addition to early allogeneic stem cell transplantation for this high risk subgroup.     

Bacterial Viability and Physical Properties of Antibacterially Modified Experimental Dental Resin Composites

Purpose

To investigate the antibacterial effect and the effect on the material properties of a novel delivery system with Irgasan as active agent and methacrylated polymerizable Irgasan when added to experimental dental resin composites.

Materials and Methods

A delivery system based on novel polymeric hollow beads, loaded with Irgasan and methacrylated polymerizable Irgasan as active agents were used to manufacture three commonly formulated experimental resin composites. The non-modified resin was used as standard (ST). Material A contained the delivery system providing 4 % (m/m) Irgasan, material B contained 4 % (m/m) methacrylated Irgasan and material C 8 % (m/m) methacrylated Irgasan. Flexural strength (FS), flexural modulus (FM), water sorption (WS), solubility (SL), surface roughness R_a, polymerization shrinkage, contact angle Θ, total surface free energy γ_S and its apolar γ_S ^LW, polar γ_S ^AB, Lewis acid γ_S ⁺and base γ_S ^- term as well as bacterial viability were determined. Significance was p < 0.05.

Results

The materials A to C were not unacceptably influenced by the modifications and achieved the minimum values for FS, WS and SL as requested by EN ISO 4049 and did not differ from ST what was also found for R_a. Only A had lower FM than ST. Θ of A and C was higher and γ_S ^AB of A and B was lower than of ST. Materials A to C had higher γ_S ⁺ than ST. The antibacterial effect of materials A to C was significantly increased when compared with ST meaning that significantly less vital cells were found.

Conclusion

Dental resin composites with small quantities of a novel antibacterially doped delivery system or with an antibacterial monomer provided acceptable physical properties and good antibacterial effectiveness. The sorption material being part of the delivery system can be used as a vehicle for any other active agent.     

Lactic acid bacterium and yeast microbiotas of 19 sourdoughs used for traditional/typical italian breads: interactions between ingredients and microbial species diversity

The study of the microbiotas of 19 Italian sourdoughs used for the manufacture of traditional/typical breads allowed the identification, through a culture-dependent approach, of 20 and 4 species of lactic acid bacteria (LAB) and yeasts, respectively. Numerically, the most frequent LAB isolates were Lactobacillus sanfranciscensis (ca. 28% of the total LAB isolates), Lactobacillus plantarum (ca. 16%), and Lactobacillus paralimentarius (ca. 14%). Saccharomyces cerevisiae was identified in 16 sourdoughs. Candida humilis, Kazachstania barnettii, and Kazachstania exigua were also identified. As shown by principal component analysis (PCA), a correlation was found between the ingredients, especially the type of flour, the microbial community, and the biochemical features of sourdoughs. Triticum durum flours were characterized by the high level of maltose, glucose, fructose, and free amino acids (FAA) correlated with the sole or main presence of obligately heterofermentative LAB, the lowest number of facultatively heterofermentative strains, and the low cell density of yeasts in the mature sourdoughs. This study highlighted, through a comprehensive and comparative approach, the dominant microbiotas of 19 Italian sourdoughs, which determined some of the peculiarities of the resulting traditional/typical Italian breads.     

Zoonotic transmission of tuberculosis between pastoralists and their livestock in South-East Ethiopia

Despite huge global efforts in tuberculosis (TB) control, pastoral areas remain under-investigated. During two years sputum and fine needle aspirate (FNA) specimens were collected from 260 Ethiopian pastoralists of Oromia and Somali Regional States with suspected pulmonary TB and from 32 cases with suspected TB lymphadenitis. In parallel, 207 suspected tuberculous lesions were collected from cattle, camels and goats at abattoirs. All specimens were processed and cultured for mycobacteria; samples with acid-fast stained bacilli (AFB) were further characterized by molecular methods including genus and deletion typing as well as spoligotyping. Non-tuberculous mycobacteria (NTM) were sequenced at the 16S rDNA locus. Culturing of AFB from human sputum and FNA samples gave a yield of 174 (67%) and 9 (28%) isolates, respectively. Molecular typing was performed on 173 of these isolates and 160 were confirmed as Mycobacterium tuberculosis, three as M. bovis, and the remaining 10 were typed as NTMs. Similarly, 48 AFB isolates (23%) yielded from tuberculous lesions of livestock, of which 39 were molecular typed, including 24 M. bovis and 4 NTMs from cattle, 1 M. tuberculosis and 1 NTM from camels and 9 NTMs from goats. Isolation of M. bovis from humans and M. tuberculosis from livestock suggests transmission between livestock and humans in the pastoral areas of South-East Ethiopia.     

On the ATP-Dependent Activation of the Radical Enzyme (R)-2-Hydroxyisocaproyl-CoA Dehydratase

Members of the 2-hydroxyacyl-CoA dehydratase enzyme family catalyze the β,α-dehydration of various CoA-esters in the fermentation of amino acids by clostridia. Abstraction of the nonacidic β-proton of the 2-hydroxyacyl-CoA compounds is achieved by the reductive generation of ketyl radicals on the substrate, which is initiated by the transfer of an electron at low redox potentials. The highly energetic electron needed on the dehydratase is donated by a [4Fe-4S] cluster containing ATPase, termed activator. We investigated the activator of the 2-hydroxyisocaproyl-CoA dehydratase from Clostridium difficile. The activator is a homodimeric protein structurally related to acetate and sugar kinases, Hsc70 and actin, and has a [4Fe-4S] cluster bound in the dimer interface. The crystal structures of the Mg-ADP, Mg-ADPNP, and nucleotide-free states of the reduced activator have been solved at 1.6-3.0 ? resolution, allowing us to define the position of Mg(2+) and water molecules in the vicinity of the nucleotides and the [4Fe-4S] cluster. The structures reveal redox- and nucleotide dependent changes agreeing with the modulation of the reduction potential of the [4Fe-4S] cluster by conformational changes. We also investigated the propensity of the activator to form a complex with its cognate dehydratase in the presence of Mg-ADP and Mg-ADPNP and together with the structural data present a refined mechanistic scheme for the ATP-dependent electron transfer between activator and dehydratase.     

Interleukin-6 induction by Helicobacter pylori in human macrophages is dependent on phagocytosis

BACKGROUND: The colonization of the gastric mucosa with Helicobacter pylori is accompanied by elevated levels of proinflammatory cytokines, such as interleukin-1 (IL-1), IL-6, and IL-8. The aim of our study was to determine the mechanisms of IL-6 stimulation in phagocytes upon H. pylori infection. MATERIALS AND METHODS: We investigated the secretion of IL-6 by different professional phagocytes from murine and human origin, including granulocyte- and monocyte-like cells and macrophages derived from human peripheral blood monocytes (PBMCs). The influence of viability, phagocytosis, and the impact of different subcellular fractions of H. pylori bacteria were evaluated. RESULTS: IL-6 levels induced by H. pylori were low in cell lines derived from murine and human monocytes and in human granulocyte-like cells. By contrast, macrophages derived from human PBMCs were highly responsive to both H. pylori and Escherichia coli. IL-6 induction was blocked by inhibition of actin-dependent processes prior to infection with H. pylori, but not with E. coli or E. coli lipopolysaccharide (LPS). Using cell fractionation, the most activity was found in the H. pylori membrane. H. pylori LPS exhibited a 10(3)- to 10(4)-fold lower biologic activity than E. coli LPS, suggesting a minor role for toll-like receptor 4 (TLR4)-mediated signalling from the exterior. CONCLUSIONS: From these data, we conclude that macrophages may be a major source of IL-6 in the gastric mucosa upon H. pylori infection. The IL-6 induction by H. pylori in these cells is a multifactorial process, which requires the uptake and presumably degradation of H. pylori bacteria.     

Colonization of barley (Hordeum vulgare) with Salmonella enterica and Listeria spp

Colonization of barley plants by the food-borne pathogens Salmonella enterica serovar typhimurium and three Listeria spp. (L. monocytogenes, L. ivanovii, L. innocua) was investigated in a monoxenic system. Herbaspirillum sp. N3 was used as a positive control and Escherichia coli HB101 as a negative control for endophytic root colonization. Colonization of the plants was tested 1-4 weeks after inoculation by determination of CFU, specific PCR assays and fluorescence in situ hybridization (FISH) with fluorescently labelled oligonucleotide probes in combination with confocal laser scanning microscopy (CLSM). Both S. enterica strains were found as endophytic colonizers of barley roots and reached up to 2.3 x 10(6) CFU per g root fresh weight after surface sterilization. The three Listeria strains had 10-fold fewer cell numbers after surface sterilization on the roots and therefore were similar to the results of nonendophytic colonizers, such as E. coli HB101. The FISH/CSLM approach demonstrated not only high-density colonization of the root hairs and the root surface by S. enterica but also a spreading to subjacent rhizodermis layers and the inner root cortex. By contrast, the inoculated Listeria spp. colonized the root hair zone but did not colonize other parts of the root surface. Endophytic colonization of Listeria spp. was not observed. Finally, a systemic spreading of S. enterica to the plant shoot (stems and leaves) was demonstrated using a specific PCR analysis and plate count technique.