Membrane Anchoring by a C-terminal Tryptophan Enables HIV-1 Vpu to Displace Bone Marrow Stromal Antigen 2 (BST2) from Sites of Viral Assembly

The restriction factor BST2 (tetherin) prevents the release of enveloped viruses from the host cell and is counteracted by HIV-1 Vpu. Vpu and BST2 interact directly via their transmembrane domains. This interaction enables Vpu to induce the surface down-regulation and the degradation of BST2, but neither of these activities fully accounts for the ability of Vpu to enhance virion release. During a study of naturally occurring Vpu proteins, we found that a tryptophan residue near the Vpu C terminus is particularly important for enhancing virion release. Vpu proteins with a W76G polymorphism degraded and down-regulated BST2 from the cell surface, yet they inefficiently stimulated virion release. Here we explore the mechanism of this anomaly. We find that Trp-76 is critical for the ability of Vpu to displace BST2 from sites of viral assembly in the plane of the plasma membrane. This effect does not appear to involve a general reorganization of the membrane microdomains associated with virion assembly, but rather is a specific effect of Vpu on BST2. Using NMR spectroscopy, we find that the cytoplasmic domain of Vpu and Trp-76 specifically interact with lipids. Moreover, paramagnetic relaxation enhancement studies show that Trp-76 inserts into the lipid. These data are consistent with a model whereby Trp-76 anchors the C terminus of the cytoplasmic tail of Vpu to the plasma membrane, enabling the movement of Vpu-bound BST2 away from viral assembly sites.     

A new species of Leopoldia (Asparagaceae Scilloideae formerly Hyacinthaceae) from Iran

Leopoldia tabriziana Jafari (Hyacinthaceae) from northwest of Iran (East Azarbaijan province) is described here and illustrated by a line‐drawing. It is similar to L. comosa Parl . but differs in having violet (not cream) pedicels in the fresh fertile flowers, oblong‐campanulate (not oblong‐urceolate) fertile flowers, triangular‐obovate (not globose‐obovate) sterile flowers, dark violet (not beige) fertile flowers and dark violet (not pale violet) sterile flowers with much shorter pedicels. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and antiplatelet effects of an isoxazole series of glycoprotein IIb/IIIa antagonists

Despite the excellent in vitro potency of a series of benzamide glycoprotein IIb/IIIa antagonists, which have been reported previously, poor in vivo potency in the inhibition of platelet aggregation was observed when the most potent inhibitor XU057 was dosed intravenously to dogs. In this communication, we report that replacement of the benzamide in XU057 with an isoxazolecarboxamide resulted in significant improvement in in vivo potency. More importantly, the analogue XU065 showed an excellent oral antiplatelet effect in dogs.     

Stress inhibits psychomotor performance differently in simple and complex open field environments

Stress affects psychomotor profiles and exploratory behavior in response to environmental features. Here we investigated psychomotor and exploratory patterns induced by stress in a simple open-field arena and a complex, multi-featured environment. Groups of rats underwent seven days of restraint stress or no-stress conditions and were individually tested in three versions of the ziggurat task (ZT) that varied according to environmental complexity. The hyperactivity of the hypothalamic–pituitary–adrenal (HPA) axis due to stress procedure was evaluated by the pre- and post-stress levels of circulating corticosterone (CORT). Horizontal activity, exploration, and motivation were measured by the number of fields entered, the time spent in the central fields, path length and speed, and stop duration. In addition, vertical exploratory behavior was measured by the times rats climbed onto ziggurats. Stress-induced psychomotor changes were indicated by reduced path length and path speed and increased duration of stops only within the complex arena of the ZT. Rats in stress groups also showed a significant decline in the vertical movements as measured by the number of climbing onto ziggurats. No stress-induced changes were revealed by the simple open-field arena. The exploratory patterns of stressed animals suggest psychomotor inhibition and reduced novelty-seeking behaviors in an environment-dependent manner. Thus, multi-featured arenas that require complex behavioral strategies are ideally suited to reveal the inhibitory effects of stress on psychomotor capabilities in rodents.     

Join queries optimization in the distributed databases using a hybrid multi-objective algorithm

Cluster Computing - In the distributed database systems, the relations needed by a query can be kept in several locations. This process significantly increases potential corresponding Query...     

Enhanced h6h transcript level,antioxidant activity and tropane alkaloid production in Hyoscyamus reticulatus L. hairy roots elicited by acetylsalicylic acid

Hyoscyamine (Hyos) and scopolamine (SCP) are drugs widely used as antimuscarinic to treat diseases such as Parkinson’s or to calm schizoid patients. In this study, with the aim of enhancing tropane alkaloid production in H. reticulatus hairy root cultures, the effects of the signalling molecule acetylsalicylic acid (ASA) were investigated at different concentrations (0, 0.01, 0.1 and 1 mM) and inoculation times (24 and 48 h). As well as reducing biomass production, ASA treatment significantly enhanced the activity of catalase, guaiacol peroxidase and ascorbate peroxidase (p < 0.01), which was highest at 48 h of exposure to 1 mM of ASA. The highest accumulation of Hyos and SCP (1.6- and 3.5-fold more than in the control, respectively) was obtained at 24 h of exposure to 0.1 mM ASA. Additionally, semi-quantitative RT-PCR analysis showed an increased expression of the hyoscyamine-6-beta-hydroxylase (h6h) gene, involved in the last Hyos and SCP biosynthetic step, which correlated with the enhanced level of Hyos and SCP production under ASA elicitation. Our findings suggest that ASA, by stimulating the expression of key biosynthetic genes and enzymes, can be applied to increase commercial tropane alkaloid production in a H. reticulatus hairy root system.     

CFD simulation of mass transfer and flow behaviour around a single particle in bioleaching process

The pathway to reach a certain target in many processes such as bioleaching, due to the complex and poorly understood hydrodynamics, reaction kinetics, and chemistry knowledge involved is not apparent. An investigation of the interactions between the parameters in bioleaching process can be applied to optimize the rate of metal extraction from sulphide minerals. Such investigations can be carried out with the aid of numerical simulations. In this study, a computational fluid dynamics (CFD) model was developed to better understand the mass transfer phenomenon and complex flow field around a single particle. The commercial software FLUENT 6.2 has been employed to solve the governing equations. Volume of fluid (VOF) method was used to predict the fluid volume fraction in a 3D geometry. The computational model has successfully captured the results observed in the experiments. Simulation results indicate that concentrations of species in a thin layer of liquid on the particle surface are much higher than their concentrations in the liquid bulk and significant gradients in the ion concentrations between the surface of the particle and the liquid bulk were observed.     

Potential of the genetically transformed root cultures of Plumbago europaea for biomass and plumbagin production

Plumbago europaea L. is the main source of plumbagin which is a well-known pharmacological active compound. In this investigation, genetically transformed roots of P. europaea were obtained by improving some factors affecting the efficiency of Agrobacterium rhizoigenes-mediated transformation such as explant type, A. rhizoigenes strain, bacterial infection period, co-cultivation period and acetosyringone concentration. The leaf, hypocotyl and stem explants from in vitro grown plantlets were infected with bacterial strains (A4, ATCC15834, MSU440 and A13). The highest transformation rate of 69.3% was achieved after 7–9 days by inoculating A. rhizogenes MSU440 strain onto the 3-week-old stem explants followed by a co-cultivation period of 2 days on a medium containing 100 μM acetosyringone. To investigate the existence of the rolB gene, polymerase chain reaction was carried out using specific primers. Effects of growth media (MS, 1/2 MS, MS-B5 and ½ MS-B5), different sucrose concentrations and illumination on biomass production and plumbagin biosynthesis in P. europaea hairy root cultures were analyzed using stem explants after infection with MSU440 strain. ½ MS-B5 liquid medium containing 30 g L⁻¹ sucrose incubated in the dark resulted in the efficient biomass production of transformed hairy roots (12.5 g fresh weight, 1.8 g dry weight) with 3.2 mg g⁻¹ DW plumbagin accumulation. This procedure provides a framework for large-scale cultivation of hairy roots for plumbagin production. This is the first report describing the establishment of P. europaea hairy root culture with special emphasis on plumbagin production.