Identification and characterization of equine herpesvirus type 1 pUL56 and its role in virus-induced downregulation of major histocompatibility complex class I

Major histocompatibility complex class I (MHC-I) molecules play an important role in host immunity to infection by presenting antigenic peptides to cytotoxic T lymphocytes (CTLs), which recognize and destroy virus-infected cells. Members of the Herpesviridae have developed multiple mechanisms to avoid CTL recognition by virtue of downregulation of MHC-I on the cell surface. We report here on an immunomodulatory protein involved in this process, pUL56, which is encoded by ORF1 of equine herpesvirus type 1 (EHV-1), an alphaherpesvirus. We show that EHV-1 pUL56 is a phosphorylated early protein which is expressed as different forms and predominantly localizes to Golgi membranes. In addition, the transmembrane (TM) domain of the type II membrane protein was shown to be indispensable for correct subcellular localization and a proper function. pUL56 by itself is not functional with respect to interference with MHC-I and likely needs another unidentified viral protein(s) to perform this action. Surprisingly, pUL49.5, an inhibitor of the transporter associated with antigen processing (TAP) and encoded by EHV-1 and related viruses, appeared not to be required for pUL56-induced early MHC-I downmodulation in infected cells. In conclusion, our data identify a new immunomodulatory protein, pUL56, involved in MHC-I downregulation which is unable to perform its function outside the context of viral infection.     

Dip listening or modulation masking? Call recognition by green treefrogs (Hyla cinerea) in temporally fluctuating noise

Despite the importance of perceptually separating signals from background noise, we still know little about how nonhuman animals solve this problem. Dip listening, an ability to catch meaningful ‘acoustic glimpses’ of a target signal when fluctuating background noise levels momentarily drop, constitutes one possible solution. Amplitude-modulated noises, however, can sometimes impair signal recognition through a process known as modulation masking. We asked whether fluctuating noise simulating a breeding chorus affects the ability of female green treefrogs (Hyla cinerea) to recognize male advertisement calls. Our analysis of recordings of the sounds of green treefrog choruses reveal that their levels fluctuate primarily at rates below 10?Hz. In laboratory phonotaxis tests, we found no evidence for dip listening or modulation masking. Mean signal recognition thresholds in the presence of fluctuating chorus-like noises were never statistically different from those in the presence of a non-fluctuating control. An analysis of statistical effects sizes indicates that masker fluctuation rates, and the presence versus absence of fluctuations, had negligible effects on subject behavior. Together, our results suggest that females listening in natural settings should receive no benefits, nor experience any additional constraints, as a result of level fluctuations in the soundscape of green treefrog choruses.     

Enhancement of late successional plants on ex-arable land by soil inoculations

Restoration of species-rich grasslands on ex-arable land can help the conservation of biodiversity but faces three big challenges: absence of target plant propagules, high residual soil fertility and restoration of soil communities. Seed additions and top soil removal can solve some of these constraints, but restoring beneficial biotic soil conditions remains a challenge. Here we test the hypotheses that inoculation of soil from late secondary succession grasslands in arable receptor soil enhances performance of late successional plants, especially after top soil removal but pending on the added dose. To test this we grew mixtures of late successional plants in arable top (organic) soil or in underlying mineral soil mixed with donor soil in small or large proportions. Donor soils were collected from different grasslands that had been under restoration for 5 to 41 years, or from semi-natural grassland that has not been used intensively. Donor soil addition, especially when collected from older restoration sites, increased plant community biomass without altering its evenness. In contrast, addition of soil from semi-natural grassland promoted plant community evenness, and hence its diversity, but reduced community biomass. Effects of donor soil additions were stronger in mineral than in organic soil and larger with bigger proportions added. The variation in plant community composition was explained best by the abundances of nematodes, ergosterol concentration and soil pH. We show that in controlled conditions inoculation of soil from secondary succession grassland into ex-arable land can strongly promote target plant species, and that the role of soil biota in promoting target plant species is greatest when added after top soil removal. Together our results point out that transplantation of later secondary succession soil can promote grassland restoration on ex-arable land.     

Drosophila Left/Right Asymmetry Establishment Is Controlled by the Hox Gene Abdominal-B

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Highlights? Abd-B directs the earliest steps of Drosophila left/right asymmetry establishment ? Abd-B directly regulates expression of the dextral determinant-encoding gene myoID ? Abd-B controls the two opposite dextral and sinistral left/right pathways ? Abd-B absence leads to the symmetrical development of normally asymmetric organs     

Protection of Armadillo/β-Catenin by Armless,a Novel Positive Regulator of Wingless Signaling

The Wingless (Wg/Wnt) signaling pathway is essential for metazoan development, where it is central to tissue growth and cellular differentiation. Deregulated Wg pathway activation underlies severe developmental abnormalities, as well as carcinogenesis. Armadillo/β-Catenin plays a key role in the Wg transduction cascade; its cytoplasmic and nuclear levels directly determine the output activity of Wg signaling and are thus tightly controlled. In all current models, once Arm is targeted for degradation by the Arm/β-Catenin destruction complex, its fate is viewed as set. We identified a novel Wg/Wnt pathway component, Armless (Als), which is required for Wg target gene expression in a cell-autonomous manner. We found by genetic and biochemical analyses that Als functions downstream of the destruction complex, at the level of the SCF/Slimb/βTRCP E3 Ub ligase. In the absence of Als, Arm levels are severely reduced. We show by biochemical and in vivo studies that Als interacts directly with Ter94, an AAA ATPase known to associate with E3 ligases and to drive protein turnover. We suggest that Als antagonizes Ter94''s positive effect on E3 ligase function and propose that Als promotes Wg signaling by rescuing Arm from proteolytic degradation, spotlighting an unexpected step where the Wg pathway signal is modulated.     

Influence of altered gait patterns on the hip joint contact forces

Children who exhibit gait deviations often present a range of bone deformities, particularly at the proximal femur. Altered gait may affect bone growth and lead to deformities by exerting abnormal stresses on the developing bones. The objective of this study was to calculate variations in the hip joint contact forces with different gait patterns. Muscle and hip joint contact forces of four children with different walking characteristics were calculated using an inverse dynamic analysis and a static optimisation algorithm. Kinematic and kinetic analyses were based on a generic musculoskeletal model scaled down to accommodate the dimensions of each child. Results showed that for all the children with altered gaits both the orientation and magnitude of the hip joint contact force deviated from normal. The child with the most severe gait deviations had hip joint contact forces 30% greater than normal, most likely due to the increase in muscle forces required to sustain his crouched stance. Determining how altered gait affects joint loading may help in planning treatment strategies to preserve correct loading on the bone from a young age.     

New tricks of an old enemy: isolates of Fusarium graminearum produce a type A trichothecene mycotoxin

The ubiquitous filamentous fungus Fusarium graminearum causes the important disease Fusarium head blight on various species of cereals, leading to contamination of grains with mycotoxins. In a survey of F. graminearum (sensu stricto) on wheat in North America several novel strains were isolated, which produced none of the known trichothecene mycotoxins despite causing normal disease symptoms. In rice cultures, a new trichothecene mycotoxin (named NX‐2) was characterized by liquid chromatography‐tandem mass spectrometry. Nuclear magnetic resonance measurements identified NX‐2 as 3α‐acetoxy‐7α,15‐dihydroxy‐12,13‐epoxytrichothec‐9‐ene. Compared with the well‐known 3‐acetyl‐deoxynivalenol (3‐ADON), it lacks the keto group at C‐8 and hence is a type A trichothecene. Wheat ears inoculated with the isolated strains revealed a 10‐fold higher contamination with its deacetylated form, named NX‐3, (up to 540 mg kg^?1) compared with NX‐2. The toxicities of the novel mycotoxins were evaluated utilizing two in vitro translation assays and the alga Chlamydomonas reinhardtii. NX‐3 inhibits protein biosynthesis to almost the same extent as the prominent mycotoxin deoxynivalenol, while NX‐2 is far less toxic, similar to 3‐ADON. Genetic analysis revealed a different TRI1 allele in the N‐isolates, which was verified to be responsible for the difference in hydroxylation at C‐8.     

A technique for the intra-gastric administration of live larvae of Anisakis simplex in mice

To understand the mechanisms of infection and to attempt to simulate human infection by the Anisakidae family, many in vivo experimental approaches have been developed. The aim was to develop and present a technique for the induction of an oral infection through the use of an intra-gastric gavage of live Anisakis simplex in mice. A commercial pediatric gastric tube (No. 4) was cut longitudinally to produce a 3-cm slit at the distal end where the larva was placed to then be administered to the stomach of the mouse. There were no abnormal clinical complications before, during or after the procedure. In conclusion oral infection through the direct delivery of larvae in the stomach is simple and effective.     

The yeast mitochondrial carrier proteins Mrs3p/Mrs4p mediate iron transport across the inner mitochondrial membrane

The yeast proteins Mrs3p and Mrs4p are two closely related members of the mitochondrial carrier family (MCF), which had previously been implicated in mitochondrial Fe²⁺ homeostasis. A vertebrate Mrs3/4 homologue named mitoferrin was shown to be essential for erythroid iron utilization and proposed to function as an essential mitochondrial iron importer. Indirect reporter assays in isolated yeast mitochondria indicated that the Mrs3/4 proteins are involved in mitochondrial Fe²⁺ utilization or transport under iron-limiting conditions. To have a more direct test for Mrs3/4p mediated iron uptake into mitochondria we studied iron (II) transport across yeast inner mitochondrial membrane vesicles (SMPs) using the iron-sensitive fluorophore PhenGreen SK (PGSK). Wild-type SMPs showed rapid uptake of Fe²⁺ which was driven by the external Fe²⁺ concentration and stimulated by acidic pH. SMPs from the double deletion strain mrs3/4Δ failed to show this rapid Fe²⁺ uptake, while SMPs from cells overproducing Mrs3/4p exhibited increased Fe²⁺ uptake rates. Cu²⁺ was transported at similar rates as Fe²⁺, while other divalent cations, such as Zn²⁺ and Cd²⁺ apparently did not serve as substrates for the Mrs3/4p transporters. We conclude that the carrier proteins Mrs3p and Mrs4p transport Fe²⁺ across the inner mitochondrial membrane. Their activity is dependent on the pH gradient and it is stimulated by iron shortage.