Role of f02 in fluid saturation of oceanic basalt.

Assessing the conditions under which magmas become fluid-saturated has important bearings on the geochemical modelling of magmas because volatile exsolution may profoundly alter the behaviour of certain trace elements that are strongly partitioned in the coexisting fluid1. Saal et al.2 report primitive melt inclusions from dredged oceanic basalts of the Siqueiros transform fault, from which they derive volatile abundances of the depleted mantle, based on the demonstration that magmas are not fluid-saturated at their eruption depth and so preserve the mantle signature in terms of their volatile contents. However, in their analysis, Saal et al.2 consider only fluid−melt equilibria, and do not take into account the homogeneous equilibria between fluid species, which, as we show here, may lead to a significant underestimation of the pressure depth of fluid saturation

Biohydrogenation of 22:6n-3 by Butyrivibrio proteoclasticus P18

Background: Rumen microbes metabolize 22:6n-3. However, pathways of 22:6n-3 biohydrogenation and ruminal microbes involved in this process are not known. In this study, we examine the ability of the well-known rumen biohydrogenating bacteria, Butyrivibrio fibrisolvens D1 and Butyrivibrio proteoclasticus P18, to hydrogenate 22:6n-3. Results: Butyrivibrio fibrisolvens D1 failed to hydrogenate 22:6n-3 (0.5 to 32 mu g/mL) in growth medium containing autoclaved ruminal fluid that either had or had not been centrifuged. Growth of B. fibrisolvens was delayed at the higher 22:6n-3 concentrations; however, total volatile fatty acid production was not affected. Butyrivibrio proteoclasticus P18 hydrogenated 22:6n-3 in growth medium containing autoclaved ruminal fluid that either had or had not been centrifuged. Biohydrogenation only started when volatile fatty acid production or growth of B. proteoclasticus P18 had been initiated, which might suggest that growth or metabolic activity is a prerequisite for the metabolism of 22:6n-3. The amount of 22:6n-3 hydrogenated was quantitatively recovered in several intermediate products eluting on the gas chromatogram between 22:6n-3 and 22:0. Formation of neither 22:0 nor 22:6 conjugated fatty acids was observed during 22:6n-3 metabolism. Extensive metabolism was observed at lower initial concentrations of 22:6n-3 (5, 10 and 20 mu g/mL) whereas increasing concentrations of 22:6n-3 (40 and 80 mu g/mL) inhibited its metabolism. Stearic acid formation (18:0) from 18:2n-6 by B. proteoclasticus P18 was retarded, but not completely inhibited, in the presence of 22:6n-3 and this effect was dependent on 22:6n-3 concentration. Conclusions: For the first time, our study identified ruminal bacteria with the ability to hydrogenate 22:6n-3. The gradual appearance of intermediates indicates that biohydrogenation of 22:6n-3 by B. proteoclasticus P18 occurs by pathways of isomerization and hydrogenation resulting in a variety of unsaturated 22 carbon fatty acids. During the simultaneous presence of 18:2n-6 and 22:6n-3, B. proteoclasticus P18 initiated 22:6n-3 metabolism before converting 18:1 isomers into 18:0

Inhibitors of Foot and Mouth Disease Virus Targeting a Novel Pocket of the RNA-Dependent RNA Polymerase

Foot-and-Mouth Disease Virus (FMDV) is a picornavirus that infects cloven-hoofed animals and leads to severe losses in livestock production. In the case of an FMD outbreak, emergency vaccination requires at least 7 days to trigger an effective immune response. There are currently no approved inhibitors for the treatment or prevention of FMDV infections.Using a luciferase-based assay we screened a library of compounds and identified seven novel inhibitors of 3Dpol, the RNA-dependent RNA polymerase of FMDV. The compounds inhibited specifically 3Dpol (IC(50)s from 2-17 µM) and not other viral or bacterial polymerases. Enzyme kinetic studies on the inhibition mechanism by compounds 5D9 and 7F8 showed that they are non-competitive inhibitors with respect to NTP and nucleic acid substrates. Molecular modeling and docking studies into the 3Dpol structure revealed an inhibitor binding pocket proximal to, but distinct from the 3Dpol catalytic site. Residues surrounding this pocket are conserved among all 60 FMDV subtypes. Site directed mutagenesis of two residues located at either side of the pocket caused distinct resistance to the compounds, demonstrating that they indeed bind at this site. Several compounds inhibited viral replication with 5D9 suppressing virus production in FMDV-infected cells with EC(50) = 12 µM and EC(90) = 20 µM).We identified several non-competitive inhibitors of FMDV 3Dpol that target a novel binding pocket, which can be used for future structure-based drug design studies. Such studies can lead to the discovery of even more potent antivirals that could provide alternative or supplementary options to contain future outbreaks of FMD

Cosmopolitan distribution of Endozoicomonas-like organisms and other intracellular microcolonies of bacteria causing infection in marine molluscs

Intracellular microcolonies of bacteria, in some cases developing large extracellular cysts, have been historically reported infecting a wide diversity of economically important mollusc species worldwide, sometimes associated with severe lesions and mass mortality events. As an effort to characterise those organisms, traditionally named as Rickettsia or Chlamydia -like organisms (RLO/CLO), via international collaboration, 98 samples comprising 20 mollusc species were collected over 10 countries and examined using histology and phylogenetic analysis. A 16S rRNA gene amplicon library-based sequencing showed the presence of different species of Endozoicomonas-like organisms (ELO) in all the mollusc species analysed, infecting primarily gill and digestive glands. Co-infections of ELOs with other intracellular bacteria were also observed. Subsequent phylogenetic analysis of Operational Taxonomic Units (OTU) revealed a novel microbial diversity associated with molluscan RLO/CLOs infection distributed along different taxa, including Spirochaetes phyla, Rickettsiales order, Simkaniaceae family, Mycoplasma and Francisella genera, and sulfur-oxidizing endosymbionts. Sequences like Francisella halioticida/philomiragia and Candidatus Brownia rhizoecola were also obtained. The presence of ELO sequences in the RLO/CLO infection was confirmed by standard PCR, Sanger sequencing, and by in situ hybridisation in a selection of samples. The phylogenetic analysis conducted in this study will allow for further characterization of the microbial community associated with Rickettsia and Chlamydia-like infection in marine molluscs and their correlation with severity of the lesions in order to reveal their role as endosymbionts, commensals or true pathogens.info:eu-repo/semantics/publishedVersio

Eicosapentaenoic Acid, Arachidonic Acid and Eicosanoid Metabolism in Juvenile Barramundi Lates calcarifer

A two part experiment was conducted to assess the response of barramundi (Lates calcarifer; initial weight=10.3±0.03g; mean±S.D.) fed one of five diets with varying eicosapentaenoic acid (diets 1, 5, 10, 15 and 20g/kg) or one of four diets with varying arachidonic acid (1, 6, 12, 18g/kg) against a fish oil control diet. After 6weeks of feeding, the addition of EPA or ARA did not impact on growth performance or feed utilisation. Analysis of the whole body fatty acids showed that these reflected those of the diets. The ARA retention demonstrated an inversely related curvilinear response to either EPA or ARA. The calculated marginal utilisation efficiencies of EPA and ARA were high (62.1 and 91.9% respectively) and a dietary ARA requirement was defined (0.012g/kg0.796/day). The partial cDNA sequences of genes regulating eicosanoid biosynthesis were identified in barramundi tissues, namely cyclooxygenase 1 (Lc COX1a, Lc COX1b), cyclooxygenase 2 (Lc COX2) and lipoxygenase (Lc ALOX-5). BothLc COX2andLc ALOX-5expression in the liver tissue were elevated in response to increasing dietary ARA, meanwhile expression levels ofLcCOX2and the mitochondrial fatty acid oxidation gene carnitine palmitoyltransferase 1 (LcCPT1a) were elevated in the kidney. A low level of EPA increased the expression ofLc COX1bin the liver. Consideration should be given to the EPA to ARA balance for juvenile barramundi in light of nutritionally inducible nature of the cyclooxygenase and lipoxygenase enzymes

Plant traits poorly predict winner and loser shrub species in a warming tundra biome

Climate change is leading to species redistributions. In the tundra biome, shrubs are generally expanding, but not all tundra shrub species will benefit from warming. Winner and loser species, and the characteristics that may determine success or failure, have not yet been fully identified. Here, we investigate whether past abundance changes, current range sizes and projected range shifts derived from species distribution models are related to plant trait values and intraspecific trait variation. We combined 17,921 trait records with observed past and modelled future distributions from 62 tundra shrub species across three continents. We found that species with greater variation in seed mass and specific leaf area had larger projected range shifts, and projected winner species had greater seed mass values. However, trait values and variation were not consistently related to current and projected ranges, nor to past abundance change. Overall, our findings indicate that abundance change and range shifts will not lead to directional modifications in shrub trait composition, since winner and loser species share relatively similar trait spaces

Disavowing 'the' prison

This chapter confronts the idea of ‘the’ prison, that is, prison as a fixed entity. However hard we, that is, prison scholars including ourselves, seek to deconstruct and critique specific aspects of confinement, there is a tendency to slip into a default position that envisions the prison as something given and pre-understood. When it comes to prison our imagination seems to clog up. It is the political solution to its own failure, and the preferred metaphor for its own representation

Local flexibility in feeding behaviour and contrasting microhabitat use of an omnivore across latitudes

As the environment is getting warmer and species are redistributed, consumers can be forced to adjust their interactions with available prey, and this could have cascading effects within food webs. To better understand the capacity for foraging flexibility, our study aimed to determine the diet variability of an ectotherm omnivore inhabiting kelp forests, the sea urchin Echinus esculentus, along its entire latitudinal distribution in the northeast Atlantic. Using a combination of gut content and stable isotope analyses, we determined the diet and trophic position of sea urchins at sites in Portugal (42° N), France (49° N), southern Norway (63° N), and northern Norway (70° N), and related these results to the local abundance and distribution of putative food items. With mean estimated trophic levels ranging from 2.4 to 4.6, omnivory and diet varied substantially within and between sites but not across latitudes. Diet composition generally reflected prey availability within epiphyte or understorey assemblages, with local affinities demonstrating that the sea urchin adjusts its foraging to match the small-scale distribution of food items. A net “preference” for epiphytic food sources was found in northern Norway, where understorey food was limited compared to other regions. We conclude that diet change may occur in response to food source redistribution at multiple spatial scales (microhabitats, sites, regions). Across these scales, the way that key consumers alter their foraging in response to food availability can have important implication for food web dynamics and ecosystem functions along current and future environmental gradients