Human cytomegalovirus inhibits apoptosis by proteasome-mediated degradation of bax at endoplasmic reticulum-mitochondrion contacts

Human cytomegalovirus (HCMV) encodes the UL37 exon 1 protein (pUL37x1), which is the potent viral mitochondrion-localized inhibitor of apoptosis (vMIA), to increase survival of infected cells. HCMV vMIA traffics from the endoplasmic reticulum (ER) to ER subdomains, which are physically linked to mitochondria known as mitochondrion-associated membranes (MAM), and to mitochondria. The antiapoptotic function of vMIA is thought to primarily result from its ability to inhibit Bax-mediated permeabilization of the outer mitochondrial membrane (OMM). Here, we establish that vMIA retargets Bax to the MAM as well as to the OMM from immediate early through late times of infection. However, MAM localization of Bax results in its increased ubiquitination and proteasome-mediated degradation. Surprisingly, HCMV infection does not increase OMM-associated degradation (OMMAD) of Bax, even though the ER and mitochondria are physically connected at the MAM. It was recently found that lipid rafts at the plasma membrane can connect extrinsic and intrinsic apoptotic pathways and can serve as sites of apoptosome assembly. In transfected permissive human fibroblasts, vMIA mediates, through its cholesterol affinity, association of Bax and apoptosome components with MAM lipid rafts. While Bax association with MAM lipid rafts was detected in HCMV-infected cells, association of apoptosome components was not. These results establish that Bax recruitment to the MAM and its MAM-associated degradation (MAMAD) are a newly described antiapoptotic mechanism used by HCMV infection to increase cell survival for its growth

Generalized Sagnac Effect

Experiments were conducted to study light propagation in a light waveguide loop consisting of linearly and circularly moving segments. We found that any segment of the loop contributes to the total phase difference between two counterpropagating light beams in the loop. The contribution is proportional to a product of the moving velocity v and the projection of the segment length Deltal on the moving direction, Deltaphi=4pivDeltal/clambda. It is independent of the type of motion and the refractive index of waveguides. The finding includes the Sagnac effect of rotation as a special case and suggests a new fiber optic sensor for measuring linear motion with nanoscale sensitivity.Comment: 3 pages (including 3 figures

Azithromycin effectiveness against intracellular infections of Francisella

<p>Abstract</p> <p>Background</p> <p>Macrolide antibiotics are commonly administered for bacterial respiratory illnesses. Azithromycin (Az) is especially noted for extremely high intracellular concentrations achieved within macrophages which is far greater than the serum concentration. Clinical strains of Type B <it>Francisella </it>(<it>F.</it>) <it>tularensis </it>have been reported to be resistant to Az, however our laboratory <it>Francisella </it>strains were found to be sensitive. We hypothesized that different strains/species of <it>Francisella </it>(including Type A) may have different susceptibilities to Az, a widely used and well-tolerated antibiotic.</p> <p>Results</p> <p><it>In vitro </it>susceptibility testing of Az confirmed that <it>F. tularensis subsp. holarctica </it>Live Vaccine Strain (LVS) (Type B) was not sensitive while <it>F. philomiragia, F. novicida</it>, and Type A <it>F. tularensis </it>(NIH B38 and Schu S4 strain) were susceptible. In J774A.1 mouse macrophage cells infected with <it>F. philomiragia, F. novicida</it>, and <it>F. tularensis </it>LVS, 5 μg/ml Az applied extracellularly eliminated intracellular <it>Francisella </it>infections. A concentration of 25 μg/ml Az was required for <it>Francisella-</it>infected A549 human lung epithelial cells, suggesting that macrophages are more effective at concentrating Az than epithelial cells. Mutants of RND efflux components (<it>tolC </it>and <it>ftlC</it>) in <it>F. novicida </it>demonstrated less sensitivity to Az by MIC than the parental strain, but the <it>tolC </it>disc-inhibition assay demonstrated increased sensitivity, indicating a complex role for the outer-membrane transporter. Mutants of <it>acrA </it>and <it>acrB </it>mutants were less sensitive to Az than the parental strain, suggesting that AcrAB is not critical for the efflux of Az in <it>F. novicida</it>. In contrast, <it>F. tularensis </it>Schu S4 mutants Δ<it>acrB </it>and Δ<it>acrA </it>were more sensitive than the parental strain, indicating that the AcrAB may be important for Az efflux in <it>F. tularensis </it>Schu S4. <it>F. novicida </it>LPS O-antigen mutants (<it>wbtN, wbtE, wbtQ </it>and <it>wbtA</it>) were found to be less sensitive <it>in vitro </it>to Az compared to the wild-type. Az treatment prolonged the survival of <it>Galleria </it>(<it>G</it>.) <it>mellonella </it>infected with <it>Francisella</it>.</p> <p>Conclusion</p> <p>These studies demonstrate that Type A <it>Francisella </it>strains, as well as <it>F. novicida </it>and <it>F. philomiragia</it>, are sensitive to Az <it>in vitro. Francisella </it>LPS and the RND efflux pump may play a role in Az sensitivity. Az also has antimicrobial activity against intracellular <it>Francisella</it>, suggesting that the intracellular concentration of Az is high enough to be effective against multiple strains/species of <it>Francisella</it>, especially in macrophages. Az treatment prolonged survival an <it>in vivo </it>model of <it>Francisella-</it>infection.</p

Mutations affecting cleavage at the p10-capsid protease cleavage site block Rous sarcoma virus replication

A series of amino acid substitutions (M239F, M239G, P240F, V241G) were placed in the p10-CA protease cleavage site (VVAM*PVVI) to change the rate of cleavage of the junction. The effects of these substitutions on p10-CA cleavage by RSV PR were confirmed by measuring the kinetics of cleavage of model peptide substrates containing the wild type and mutant p10-CA sites. The effects of these substitutions on processing of the Gag polyprotein were determined by labeling Gag transfected COS-1 cells with (35)S-Met and -Cys, and immunoprecipitation of Gag and its cleavage products from the media and lysate fractions. All substitutions except M239F caused decreases in detectable Gag processing and subsequent release from cells. Several of the mutants also caused defects in production of the three CA proteins. The p10-CA mutations were subcloned into an RSV proviral vector (RCAN) and introduced into a chick embryo fibroblast cell line (DF-1). All of the mutations except M239F blocked RSV replication. In addition, the effects of the M239F and M239G substitutions on the morphology of released virus particles were examined by electron microscopy. While the M239F particles appeared similar to wild type particles, M239G particles contained cores that were large and misshapen. These results suggest that mutations affecting cleavage at the p10-CA protease cleavage site block RSV replication and can have a negative impact on virus particle morphology

Ferroelectric Sm-doped BiMnO3 thin films with ferromagnetic transition temperature enhanced to 140 K.

A combined chemical pressure and substrate biaxial pressure crystal engineering approach was demonstrated for producing highly epitaxial Sm-doped BiMnO(3) (BSMO) films on SrTiO(3) single crystal substrates, with enhanced magnetic transition temperatures, TC up to as high as 140 K, 40 K higher than that for standard BiMnO(3) (BMO) films. Strong room temperature ferroelectricity with piezoresponse amplitude, d(33) = 10 pm/V, and long-term retention of polarization were also observed. Furthermore, the BSMO films were much easier to grow than pure BMO films, with excellent phase purity over a wide growth window. The work represents a very effective way to independently control strain in-plane and out-of-plane, which is important not just for BMO but for controlling the properties of many other strongly correlated oxides.This research was funded by the Engineering and Physical Sciences Research Council, (EP/P50385X/1), the European Research Council (ERC-2009-AdG 247276 NOVOX). The TEM work at Texas A&M University was funded by the U.S. National Science Foundation (NSF-1007969).This is the final published manuscript. It is available online through ACS in Applied Materials and Interfaces here: http://pubs.acs.org/doi/abs/10.1021/am501351c

Thin-film design of amorphous hafnium oxide nanocomposites enabling strong interfacial resistive switching uniformity

A design concept of phase-separated amorphous nanocomposite thin films is presented that realizes interfacial resistive switching (RS) in hafnium oxide-based devices. The films are formed by incorporating an average of 7% Ba into hafnium oxide during pulsed laser deposition at temperatures ≤400°C. The added Ba prevents the films from crystallizing and leads to ∼20-nm-thin films consisting of an amorphous HfOx host matrix interspersed with ∼2-nm-wide, ∼5-to-10-nm-pitch Ba-rich amorphous nanocolumns penetrating approximately two-thirds through the films. This restricts the RS to an interfacial Schottky-like energy barrier whose magnitude is tuned by ionic migration under an applied electric field. Resulting devices achieve stable cycle-to-cycle, device-to-device, and sample-to-sample reproducibility with a measured switching endurance of ≥104 cycles for a memory window ≥10 at switching voltages of ±2 V. Each device can be set to multiple intermediate resistance states, which enables synaptic spike-timing-dependent plasticity. The presented concept unlocks additional design variables for RS devices

Interface Engineered Room-Temperature Ferromagnetic Insulating State in Ultrathin Manganite Films.

Ultrathin epitaxial films of ferromagnetic insulators (FMIs) with Curie temperatures near room temperature are critically needed for use in dissipationless quantum computation and spintronic devices. However, such materials are extremely rare. Here, a room-temperature FMI is achieved in ultrathin La0.9Ba0.1MnO3 films grown on SrTiO3 substrates via an interface proximity effect. Detailed scanning transmission electron microscopy images clearly demonstrate that MnO6 octahedral rotations in La0.9Ba0.1MnO3 close to the interface are strongly suppressed. As determined from in situ X-ray photoemission spectroscopy, O K-edge X-ray absorption spectroscopy, and density functional theory, the realization of the FMI state arises from a reduction of Mn eg bandwidth caused by the quenched MnO6 octahedral rotations. The emerging FMI state in La0.9Ba0.1MnO3 together with necessary coherent interface achieved with the perovskite substrate gives very high potential for future high performance electronic devices

Magnetic Texture in Insulating Single Crystal High Entropy Oxide Spinel Films

Magnetic insulators are important materials for a range of next generation memory and spintronic applications. Structural constraints in this class of devices generally require a clean heterointerface that allows effective magnetic coupling between the insulating layer and the conducting layer. However, there are relatively few examples of magnetic insulators which can be synthesized with surface qualities that would allow these smooth interfaces and precisely tuned interfacial magnetic exchange coupling which might be applicable at room temperature. In this work, we demonstrate an example of how the configurational complexity in the magnetic insulator layer can be used to realize these properties. The entropy-assisted synthesis is used to create single crystal (Mg0.2Ni0.2Fe0.2Co0.2Cu0.2)Fe2O4 films on substrates spanning a range of strain states. These films show smooth surfaces, high resistivity, and strong magnetic responses at room temperature. Local and global magnetic measurements further demonstrate how strain can be used to manipulate magnetic texture and anisotropy. These findings provide insight into how precise magnetic responses can be designed using compositionally complex materials that may find application in next generation magnetic devices