Some mistakes go unpunished: the evolution of "all or nothing" signalling

Many models of honest signaling, based on Zahavi's handicap principle, predict that if receivers are interested in a quality that shows continuous variation across the population of signalers, then the distribution of signal intensities will also be continuous. However, it has previously been noted that this prediction does not agree with empirical observation in many signaling systems, where signals are limited to a small number of levels despite continuous variation in the trait being signaled. Typically, there is a critical value of the trait, with all individuals with trait values on one side of the threshold using the same cheap signal, and all those with trait values on the other side of the threshold using the same expensive signal. It has already been demonstrated that these classical models naturally predict such "all-or-nothing signaling" if it is additionally assumed that receivers suffer from perceptual error in evaluating signal strength. We show that such all-or-nothing signaling is also predicted if receivers are limited to responding to the signals in one of two ways. We suggest that many ecological situations (such as the decision to attack the signaler or not, or mate with the signaler or not) involve such binary choices.     

Foliar nutrient dynamics in tidal and non-tidal freshwater forested wetlands

Foliar nutrient dynamics were studied at 8 forest stands (three non-tidal and five tidal) along the lower 30 km of the Apalachicola River system in Florida, USA, during 2008. At each site, we sampled canopy foliage and litterfall from three to four trees representative of the dominant overstory species. Foliage and litterfall were analyzed for a variety of elements including N and P and these data were used to examine differences in element concentrations, nutrient ratios (C:P, C:N, and N:P), nutrient use efficiency, and nutrient proficiency. Measurements of tree diameter at basal height (DBH) at each plot were used with species allometric equations to estimate forest litterfall dry weight and N and P flux in non-tidal and tidal wetlands. Both non-tidal and tidal wetlands showed evidence of P limitation based on N:P ratios, but absolute levels of P were determined to be extremely low in tidal wetlands based on higher nutrient use efficiencies (measures of both P resorption efficiency and proficiency). Differences in P concentrations and fluxes between tidal and non-tidal wetlands are probably related to longer inundation and hydrologic export observed in tidal wetlands. Using estimations of annual litterfall dry weight and nutrient concentrations, N and P flux in non-tidal swamps were 2-4 times greater than in tidal wetlands. This study demonstrates the change in nutrient dynamics as wetlands shift from tidal to non-tidal conditions.     

Macrophage polarization state affects lipid composition and the channeling of exogenous fatty acids into endogenous lipid pools

Adipose-tissue-resident macrophages (ATMs) maintain metabolic homeostasis but also contribute to obesity-induced adipose tissue inflammation and metabolic dysfunction. Central to these contrasting effects of ATMs on metabolic homeostasis is the interaction of macrophages with fatty acids. Fatty acid levels are increased within adipose tissue in various pathological and physiological conditions, but appear to initiate inflammatory responses only upon interaction with particular macrophage subsets within obese adipose tissue. The molecular basis underlying these divergent outcomes is likely due to phenotypic differences between ATM subsets, although how macrophage polarization state influences the metabolism of exogenous fatty acids is relatively unknown. Herein, using stable isotope-labeled and nonlabeled fatty acids in combination with mass spectrometry lipidomics, we show marked differences in the utilization of exogenous fatty acids within inflammatory macrophages (M1 macrophages) and macrophages involved in tissue homeostasis (M2 macrophages). Specifically, the accumulation of exogenous fatty acids within triacylglycerols and cholesterol esters is significantly higher in M1 macrophages, while there is an increased enrichment of exogenous fatty acids within glycerophospholipids, ether lipids, and sphingolipids in M2 macrophages. Finally, we show that functionally distinct ATM populations in vivo have distinct lipid compositions. Collectively, this study identifies new aspects of the metabolic reprogramming that occur in distinct macrophage polarization states. The channeling of exogenous fatty acids into particular lipid synthetic pathways may contribute to the sensitivity/resistance of macrophage subsets to the inflammatory effects of increased environmental fatty acid levels.     

Single-dose mucosal immunization with a candidate universal influenza vaccine provides rapid protection from virulent H5N1, H3N2 and H1N1 viruses

Background

The sudden emergence of novel influenza viruses is a global public health concern. Conventional influenza vaccines targeting the highly variable surface glycoproteins hemagglutinin and neuraminidase must antigenically match the emerging strain to be effective. In contrast, “universal” vaccines targeting conserved viral components could be used regardless of viral strain or subtype. Previous approaches to universal vaccination have required protracted multi-dose immunizations. Here we evaluate a single dose universal vaccine strategy using recombinant adenoviruses (rAd) expressing the conserved influenza virus antigens matrix 2 and nucleoprotein.

Methodology/Principal Findings

In BALB/c mice, administration of rAd via the intranasal route was superior to intramuscular immunization for induction of mucosal responses and for protection against highly virulent H1N1, H3N2, or H5N1 influenza virus challenge. Mucosally vaccinated mice not only survived, but had little morbidity and reduced lung virus titers. Protection was observed as early as 2 weeks post-immunization, and lasted at least 10 months, as did antibodies and lung T cells with activated phenotypes. Virus-specific IgA correlated with but was not essential for protection, as demonstrated in studies with IgA-deficient animals.

Conclusion/Significance

Mucosal administration of NP and M2-expressing rAd vectors provided rapid and lasting protection from influenza viruses in a subtype-independent manner. Such vaccines could be used in the interval between emergence of a new virus strain and availability of strain-matched vaccines against it. This strikingly effective single-dose vaccination thus represents a candidate off-the-shelf vaccine for emergency use during an influenza pandemic.     

Optimization of permeability in a series of pyrrolotriazine inhibitors of IRAK4

We have developed a series of orally efficacious IRAK4 inhibitors, based on a scaffold hopping strategy and using rational structure based design. Efforts to tackle low permeability and high efflux in our previously reported pyrrolopyrimidine series (Scott et al., 2017) led to the identification of pyrrolotriazines which contained one less formal hydrogen bond donor and were intrinsically more lipophilic. Further optimisation of substituents on this pyrrolotriazine core culminated with the discovery of 30 as a promising in vivo probe to assess the potential of IRAK4 inhibition for the treatment of MyD88 mutant DLBCL in combination with a BTK inhibitor. When tested in an ABC-DLBCL model with a dual MyD88/CD79 mutation (OCI-LY10), 30 demonstrated tumour regressions in combination with ibrutinib.     

Action of a cell wall proteinase from Lactococcus lactis subsp. cremoris SK11 on bovine α s1-casein

Summary The cell wall-associated proteinase from Lactococcus lactis subsp. cremoris SK11 was partially purified and incubated with _s1-casein for various times up to 48 h. Sixteen trifluoroacetic acid-soluble oligopeptide hydrolysis products were identified by determination of the aminp acid sequence. Eleven of these oligopeptides originated from the 78-residue sequence comprising the C-terminal region of _s1-casein and were present among the products after the first 60 min of digestion. Three oligopeptides from the N-terminal region and two others from the central region of the _s1-casein sequence were also present among the early digestion products although in smaller amounts than most of the oligopeptides from the C-terminal region. No cleat consensus sequence of amino acid residues surrounding the cleavage sites could be identified.Offprint requests to: G. G. Pritchard     

Robustness of G Proteins in Alzheimer''s Disease: An Immunoblot Study

Many of the neurotransmitter systems that are altered in senile dementia of the Alzheimer type are known to mediate their effects via G proteins, yet the integrity of guanine nucleotide-binding proteins (G proteins) in Alzheimer's diseased brains has received minimal investigation. The aim of this study was to establish whether the level of G alpha subunits of five G proteins was altered in Alzheimer's disease. We used immunoblotting (Western blotting) to compare the amounts of Gi1, Gi2, GsH (heavy molecular weight), GsL (light molecular weight), and Go in the frontal cortex and hippocampus, two regions severely affected by the disease, and the cerebellum, which is less severely affected. The number of senile plaques was also quantified. We report that there was no significant difference in the level of these G alpha subunits between Alzheimer's diseased and age-matched postmortem brains. These results suggest that alterations in the amount of G protein alpha subunits are not a feature of Alzheimer's disease.     

TSE clearance during plasma products separation process by Gradiflow(TM).

BACKGROUND AND OBJECTIVES: Recent experimental evidence from rodent models suggests a potential risk for transmissible spongiform encephalopathy (TSE) transmission by blood. The emergence of a new variant Creutzfeldt-Jakob disease (vCJD) has raised increased concerns about the safety of blood components and plasma products derived from vCJD-infected donors. Recent risk-minimisation strategies have included a ban on the use of UK-sourced plasma for the preparation of licensed blood products and leukodepletion of blood donations for fear of possible transmission of the human TSE via blood or blood components. The aim of this study was to investigate the capability and efficacy of a preparative electrophoresis system (Gradiflow) in the removal of TSE contaminants during the separation of plasma products. MATERIALS AND METHODS: Using hamster adapted scrapie 263 K as a model for TSE agent, albumin and IgG separation from human plasma by Gradiflow were performed separately by spiking a 263 K scrapie microsomal fraction to the feed material at each process step. Samples from pre- and post-Gradiflow separation process were titrated to the end-point for the detection of the disease-associated, proteinase K resistant form of the pathogenic prion protein (PrP(Sc)) by Western blot. RESULTS: Under all conditions tested, a greater than 3 log(10) reduction was achieved with no PrP(Sc) detected in any of the pooled products for either of the IgG or albumin separations. These data show that Gradiflow processing has clear advantages for concurrent purification of plasma products and in-process TSE removal. CONCLUSIONS: Our findings suggest that Gradiflow process is a viable alternative to remove causative TSE agents during plasma products separation, potentially eliminating the risk of TSE agents transmission.     

Regulatory T cells suppress in vitro proliferation of virus-specific CD8+ T cells during persistent hepatitis C virus infection

The basis of chronic infection following exposure to hepatitis C virus (HCV) infection is unexplained. One factor may be the low frequency and immature phenotype of virus-specific CD8(+) T cells. The role of CD4(+)CD25(+) T regulatory (T(reg)) cells in priming and expanding virus-specific CD8(+) T cells was investigated. Twenty HLA-A2-positive patients with persistent HCV infection and 46 healthy controls were studied. Virus-specific CD8(+) T-cell proliferation and gamma interferon (IFN-gamma) frequency were analyzed with/without depletion of T(reg) cells, using peptides derived from HCV, Epstein-Barr virus (EBV), and cytomegalovirus (CMV). CD4(+)CD25(+) T(reg) cells inhibited anti-CD3/CD28 CD8(+) T-cell proliferation and perforin expression. Depletion of CD4(+)CD25(+) T(reg) cells from chronic HCV patients in vitro increased HCV and EBV peptide-driven expansion (P = 0.0005 and P = 0.002, respectively) and also the number of HCV- and EBV-specific IFN-gamma-expressing CD8(+) T cells. Although stimulated CD8(+) T cells expressed receptors for transforming growth factor beta and interleukin-10, the presence of antibody to transforming growth factor beta and interleukin-10 had no effect on the suppressive effect of CD4(+)CD25(+) regulatory T cells on CD8(+) T-cell proliferation. In conclusion, marked CD4(+)CD25(+) regulatory T-cell activity is present in patients with chronic HCV infection, which may contribute to weak HCV-specific CD8(+) T-cell responses and viral persistence.     

Dominant portion of thyrotropin-releasing hormone receptor is excluded from lipid domains. Detergent-resistant and detergent-sensitive pools of TRH receptor and Gqalpha/G11alpha protein

Some G protein-coupled receptors might be spacially targetted to discrete domains within the plasma membrane. Here we assessed the localization in membrane domains of the epitope-tagged, fluorescent version of thyrotropin-releasing hormone receptor (VSV-TRH-R-GFP) expressed in HEK293 cells. Our comparison of three different methods of cell fractionation (detergent extraction, alkaline treatment/sonication and mechanical homogenization) indicated that the dominant portion of plasma membrane pool of the receptor was totally solubilized by Triton X-100 and its distribution was similar to that of transmembrane plasma membrane proteins (glycosylated and non-glycosylated forms of CD147, MHCI, CD29, CD44, transmembrane form of CD58, Tapa1 and Na,K-ATPase). As expected, caveolin and GPI-bound proteins CD55, CD59 and GPI-bound form of CD58 were preferentially localized in detergent-resistant membrane domains (DRMs). Trimeric G proteins G(q)alpha/G(11)alpha, G(i)alpha1/G(i)alpha2, G(s)alphaL/G(s)alphaS and Gbeta were distributed almost equally between detergent-resistant and detergent-solubilized pools. In contrast, VSV-TRH-R-GFP, Galpha, Gbeta and caveolin were localized massively only in low-density membrane fragments of plasma membranes, which were generated by alkaline treatment/sonication or by mechanical homogenization of cells. These data indicate that VSV-TRH-R-GFP as well as other transmembrane markers of plasma membranes are excluded from TX-100-resistant, caveolin-enriched membrane domains. Trimeric G protein G(q)alpha/G(11)alpha occurs in both DRMs and in the bulk of plasma membranes, which is totally solubilized by TX-100.