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Staphylococcus aureus(S. aureus) strains that produce the toxin Panton-Valentine leukocidin (PVL; PVL-SA) frequently cause recurrent skin and soft tissue infections (SSTI). PVL binds to and kills human neutrophils, resulting in the formation of neutrophil extracellular traps, but the pathomechanism has not been extensively studied. Furthermore, it is unclear why some individuals colonized with PVL-SA suffer from recurring infections whereas others are asymptomatic. We thus aimed to (a) investigate how PVL exerts its pathogenicity on neutrophils and (b) identify factors that could help to explain the predisposition of patients with recurring infections.We provide genetic and pharmacological evidence that PVL-induced NET formation is independent of NADPH-oxidase and reactive oxygen species (ROS) production. Moreover, through NET proteome analysis we identified that the protein content of PVL-induced NETs is different from NETs induced by mitogen or the microbial toxin nigericin. The abundance of the proteins cathelicidin (CAMP), elastase (NE), and proteinase 3 (PRTN3) was lower on PVL-induced NETs, and as such they were unable to killS. aureus.Furthermore, we found that neutrophils from affected patients express higher levels of CD45, one of the PVL receptors, and are more susceptible to be killed at a low PVL concentration than control neutrophils. Neutrophils from patients that suffer from recurring PVL-positive infections may thus be more sensitive to PVL-induced NET formation, which might impair their ability to combat the infection.ImportanceIndividuals colonized byStaphylococcus aureusstrains that produce Panton-Valentine leukocidin (PVL-SA) often present with recurrent skin and soft-tissue infections, whilst other individuals remain asymptomatic. PVL is a toxin that kills neutrophils, which results in the formation of neutrophil extracellular traps. Traps induced by other stimuli are known to be toxic toS. aureus.We found however that NETs specifically induced by PVL are not toxic toS. aureus. Furthermore, we show that neutrophils from individuals that suffer from recurring PVL-SA infections are more sensitive to PVL-induced NET formation compared to healthy individuals. The significance of our work is in identifying a mechanism through which PVL-SA may actively counter the engagement of neutrophils. Moreover, we identified that patients with recuring PVL-SA infections may be more sensitive to this mechanism, which may help to explain their clinical condition and might provide avenues for future treatment development.

Summary Plants benefit from associations with a diverse community of root-colonizing microbes. Deciphering the mechanisms underpinning these beneficial services are of interest for improving plant productivity. We report a plant-beneficial interaction between Arabidopsis thaliana and the root microbiota under iron deprivation that is dependent on the secretion of plant-derived coumarins. Disrupting this pathway alters the microbiota and impairs plant growth in iron-limiting soil. Furthermore, the microbiota improves iron-limiting plant performance via a mechanism dependent on plant iron import and secretion of the coumarin fraxetin. This beneficial trait is strain specific yet functionally redundant across phylogenetic lineages of the microbiota. Transcriptomic and elemental analyses revealed that this interaction between commensals and coumarins promotes growth by relieving iron starvation. These results show that coumarins improve plant performance by eliciting microbe-assisted iron nutrition. We propose that the bacterial root microbiota, stimulated by secreted coumarins, is an integral mediator of plant adaptation to iron-limiting soils., Graphical Abstract, Highlights • Coumarins alter the root microbiota and improve plant growth in iron-limiting soil • The microbiota improves plant iron nutrition via a coumarin-dependent mechanism • The iron-beneficial commensal trait is taxonomically widespread but strain specific • Coumarin-microbiota interaction resolves iron starvation and regulates immune response, Iron-limiting soils are widespread, causing significant losses in plant growth and productivity. Harbort et al. show that under iron limitation, plant-secreted coumarin compounds are mediators of a beneficial plant-microbiota interaction. These specialized metabolites alter root microbiota composition and are required for microbiota-mediated plant iron uptake and immune regulation.

The popularity of non-mechanically agitated flotation machines (flotation columns) has varied significantly over the last fifty years. There are various philosophies on the use of column flotation. These range from support of the concept of all column flotation plants, to the opposite extreme where the risks are considered to outweigh any potential gains of column flotation. The majority of mineral processing engineers support the installation of columns based on a logical appraisal. In the Australian coal industry, where flotation columns have almost total dominance, the use of anything other than a column would be questioned. Column flotation is also largely the dominant flotation technology in the coal industry in the USA and China, the phosphate industry in the USA and Brazil and the iron ore industry in Brazil. These areas of dominance represent a substantial installed column capacity, but even so are restricted to specific geographic areas and commodities. Within the base metals industry flotation columns are generally accepted in the smaller capacity cleaner roles worldwide. It should be noted that a number of flotation column installations have been dismal failures, but they represent only a fraction of total column installed capacity. This paper provides an analysis of over 4000 installed flotation columns, contained in the Amec Foster Wheeler flotation database. Changing trends in column flotation use by type, commodity and geographical region are reviewed. The reasons for the numerous rises and falls in column flotation use are also discussed.

Neutrophils are essential for immune defense and can respond to infection by releasing chromatin in the form of neutrophil extracellular traps (NETs). Here we show that NETs are induced by mitogens and accompanied by induction of cell-cycle markers, including phosphorylation of the retinoblastoma protein and lamins, nuclear envelope breakdown, and duplication of centrosomes. We identify cyclin-dependent kinases 4 and 6 (CDK4/6) as essential regulators of NETs and show that the response is inhibited by the cell-cycle inhibitor p21Cip. CDK6, in neutrophils, is required for clearance of the fungal pathogen Candida albicans. Our data describe a function for CDK4/6 in immunity.

The objective of this study was to investigate whether the labyrinthine structures of ancient Egyptian mummies differ significantly from modern labyrinths. The new technique of digital volume tomography (DVT) was used to visualize the temporal bones. To obtain standardized images and measurements, precise instructions regarding volume rotation, slicing and measurements' positioning were determined. Twenty-five dimensions were obtained. The groups were compared statistically. No significant differences could be found except one cochlear diameter which proved to be significantly larger in the control group. DVT is applicable for imaging of temporal bones. Measurements might help to increase understanding of the temporal bone's structure, to aid the diagnostics of pathologies as well as to supplement the planning of surgical procedures.

The radiographic imaging of ancient Egyptian mummies has always been of great interest. Computed tomography is the method of choice to demonstrate bony pathologies with high quality. As digital volume tomography (DVT) is an extension of panoramic tomography with a very high resolution, its qualities were evaluated by examination of temporal bones of Egyptian mummy skulls. Ten Egyptian mummy skulls from the Zoological Collection Marburg, estimated 1,700-5,000 years of age, from Abydos, Philae, Theben-West and Sakkarah, were examined by DVT (3D Accuitomo, Morita, Japan). Through a rotation 360° of the X-ray source around the region of interest, a cylinder of 3 × 4 cm was captured as a three-dimensional volume. The gained data were analyzed with the help of special software on a PC. The angles of the axial, coronal and sagittal sections were arbitrarily changed to represent single structures with high resolution of 0.125 mm to analyze specific anatomical structures. In all skulls, conditions of the temporal bone and its anatomical structures were evaluated and normal as well as pathological findings evaluated in detail. The analysis of special landmarks such as the ossicular chain, cochlea, external, and internal auditory canal, facial nerve canal, and semicircular canals showed an intact ossicular chain in six temporal bones, while only isolated and dislocated ossicles were found in eight temporal bones. Besides one dehiscence of the superior semicircular canal in one temporal bone which might have led to vertigo and deafness at lifetime, all other findings were normal. Fragments of foreign bodies additionally found in the labyrinth, external ear canal and intracranially were attributed to postmortem damage. Digital volume tomography extends the imaging possibilities of CT for paleoradiological evaluation of temporal bones. With its high resolution, geometric accuracy, reconstruction capabilities, rapidness, and comparably low costs, even small bony pathologies are precisely demonstrated in a limited area. Investigations of larger numbers of specimen might reveal further details of ancient history for further interdisciplinary investigation of anthropologists, Egyptiologists, otolaryngologists, and radiologists.

International audience; Plants generate effective responses to infection by recognizing both conserved and variable pathogen-encoded molecules. Pathogens deploy virulence effector proteins into host cells, where they interact physically with host proteins to modulate defense. We generated an interaction network of plant-pathogen effectors from two pathogens spanning the eukaryote-eubacteria divergence, three classes of Arabidopsis immune system proteins, and similar to 8000 other Arabidopsis proteins. We noted convergence of effectors onto highly interconnected host proteins and indirect, rather than direct, connections between effectors and plant immune receptors. We demonstrated plant immune system functions for 15 of 17 tested host proteins that interact with effectors from both pathogens. Thus, pathogens from different kingdoms deploy independently evolved virulence proteins that interact with a limited set of highly connected cellular hubs to facilitate their diverse life-cycle strategies.

Neutrophils play an essential role in the initial stages of inflammation by balancing pro- and antiinflammatory signals. Among these signals are the production of proinflammatory cytokines and the timely initiation of antiinflammatory cell death via constitutive apoptosis. Here we identify ataxia-telangiectasia mutated (ATM) kinase as a modulator of these neutrophil functions. Ataxia-telangiectasia (AT) is a pleiotropic multisystem disorder caused by mutations in the gene-encoding ATM, a master regulator of the DNA damage response. In addition to progressive neurodegeneration and high rates of cancer, AT patients have numerous symptoms that can be linked to chronic inflammation. We report that neutrophils isolated from patients with AT overproduce proinflammatory cytokines and have a prolonged lifespan compared with healthy controls. This effect is partly mediated by increases in activation of p38 MAP kinase. Furthermore, we show that the oxidative burst, catalyzed by nicotinamide adenine dinucleotide phosphate oxidase, can activate ATM in neutrophils. Finally, activation of ATM and DNA damage signaling suppress cytokine production and can abrogate the overproduction of IL-8 in ROS-deficient cells. This reveals a novel mechanism for the regulation of cytokine production and apoptosis, establishing DNA damage as a downstream mediator of immune regulation by reactive oxygen species. We propose that deficiencies in the DNA damage response, like deficiencies in the oxidative burst seen in chronic granulomatous disease, could lead to pathologic inflammation.

It has been observed in several Jameson cell installation where the source for flotation feed is deslime screens, that the recovery of coal particles greater than 0.5 mm is not as great as that of finer material. Consequently, a research project was undertaken at a CHPP in the Bowen Basin Queensland to assess the possibility of increasing the recovery of coarser particles (+0.5 mm) within the downcomer of the Jameson cell. The effect of decreasing turbulence and agitation in a commercial-scale downcomer was investigated to assess the effect on the recovery of both coarse and fine coal particles. This paper details the findings of the test work, summarising the results relating to differences in the operating parameters within the downcomer.

Since the invention of the Jameson cell in 1986 various mechanisms have been postulated for particle collection within the cell's downcomer. Possible mechanisms include thin film migration, instantaneous collection, mixing zone collection, residence time dependence and bubble surface area flux. The limited amount of investigation to date has not provided sufficient evidence to allow one mechanism to be supported over the others. A summary of the postulated mechanisms is presented along with the background to their formulation. They are assessed on the basis of available knowledge and categorized according to specific operating parameters within the Jameson cell downcomer. In addition, relationships between operating variables and various hydrodynamic zones within the downcomer are discussed. A review of how these mechanisms relate to flotation operations is conducted for coal flotation, base-metal ore flotation and the removal of organic matter from solution.

Neutrophil extracellular trap (NET) formation is a recently discovered process in the field of innate immunity. It is important to have consistent standards in inducing and quantifying NET formation to compare data from different labs in this new area of investigation. Here we describe the conditions of neutrophil isolation from peripheral blood and stimulation that we find allow the study of NETosis in vitro. The criteria for conclusively identifying the process of NETosis, and the pros and cons of various quantification methods are discussed.

Neutrophil extracellular trap (NET) formation is a recently discovered process in the field of innate immunity. It is important to have consistent standards in inducing and quantifying NET formation to compare data from different labs in this new area of investigation. Here we describe the conditions of neutrophil isolation from peripheral blood and stimulation that we find allow the study of NETosis in vitro. The criteria for conclusively identifying the process of NETosis, and the pros and cons of various quantification methods are discussed.

A near-complete draft genome has been obtained for a single vacuolated orange Beggiatoa (Cand. Maribeggiatoa) filament from a Guaymas Basin seafloor microbial mat, the third relatively complete sequence for the Beggiatoaceae. Possible pathways for sulfide oxidation; nitrate respiration; inorganic carbon fixation by both Type II RuBisCO and the reductive tricarboxylic acid cycle; acetate and possibly formate uptake; and energy-generating electron transport via both oxidative phosphorylation and the Rnf complex are discussed here. A role in nitrite reduction is suggested for an abundant orange cytochrome produced by the Guaymas strain; this has a possible homolog in Beggiatoa (Cand. Isobeggiatoa) sp. PS, isolated from marine harbor sediment, but not Beggiatoa alba B18LD, isolated from a freshwater rice field ditch. Inferred phylogenies for the Calvin–Benson–Bassham (CBB) cycle and the reductive (rTCA) and oxidative (TCA) tricarboxylic acid cycles suggest that genes encoding succinate dehydrogenase and enzymes for carboxylation and/or decarboxylation steps (including RuBisCO) may have been introduced to (or exported from) one or more of the three genomes by horizontal transfer, sometimes by different routes. Sequences from the two marine strains are generally more similar to each other than to sequences from the freshwater strain, except in the case of RuBisCO: only the Guaymas strain encodes a Type II enzyme, which (where studied) discriminates less against oxygen than do Type I RuBisCOs. Genes subject to horizontal transfer may represent key steps for adaptation to factors such as oxygen and carbon dioxide concentration, organic carbon availability, and environmental variability.

Soil-dwelling microbes are the principal inoculum for the root microbiota, but our understanding of microbe–microbe interactions in microbiota establishment remains fragmentary. We tested 39,204 binary interbacterial interactions for inhibitory activities in vitro, allowing us to identify taxonomic signatures in bacterial inhibition profiles. Using genetic and metabolomic approaches, we identified the antimicrobial 2,4-diacetylphloroglucinol (DAPG) and the iron chelator pyoverdine as exometabolites whose combined functions explain most of the inhibitory activity of the strongly antagonistic Pseudomonas brassicacearum R401. Microbiota reconstitution with a core of Arabidopsis thaliana root commensals in the presence of wild-type or mutant strains revealed a root niche-specific cofunction of these exometabolites as root competence determinants and drivers of predictable changes in the root-associated community. In natural environments, both the corresponding biosynthetic operons are enriched in roots, a pattern likely linked to their role as iron sinks, indicating that these cofunctioning exometabolites are adaptive traits contributing to pseudomonad pervasiveness throughout the root microbiota.