Vaccinia virus 15-kilodalton (A14L) protein is essential for assembly and attachment of viral crescents to virosomes

Early stages in vaccinia virus (VV) assembly involve the recruitment of cellular membranes from the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) to virus factories (or virosomes). The key viral factors involved in this process are not yet known. We have previously identified and characterized two viral proteins, of 21 kDa (A17L gene) and 15 kDa (A14L gene), that associate with tubulovesicular elements related to the ERGIC and are localized in viral membranes at all stages of virion assembly. We showed that the 21-kDa protein is not responsible for the recruitment of membranes from the ERGIC to viral factories. However, it appears to be essential for the organization of viral membranes. In this investigation we have generated a VV recombinant, VVindA14L, in which the expression of the A14L gene is inducibly regulated by the Escherichia coli lacI operator-repressor system. Repression of 15-kDa protein synthesis has a dramatic effect on virus yields and severely impairs plaque formation. Compared to wild-type VV, reduced amounts of 15-kDa protein are produced in VVindA14L-infected cells in the presence of IPTG (isopropyl-beta-D-thiogalactoside), and this correlates with a small-plaque phenotype and reduced VVindA14L yields under these conditions. In the absence of the 15-kDa protein, early and late viral protein syntheses proceed normally; however, proteolytic cleavage of the major core precursors is inhibited. Electron microscopic examination of cells infected with VVindA14L under nonpermissive conditions reveals the presence of numerous membranous elements that look like unfinished or disassembled crescents interspersed between electron-dense masses. These abnormal membrane elements are usually well separated from the surfaces of the dense structures. These findings show that the 15-kDa protein is essential for VV morphogenesis and indicate that this polypeptide is necessary both for the correct assembly of viral crescents and for their stable attachment to the surfaces of viral factories.     

Role of the kdr and super-kdr sodium channel mutations in pyrethroid resistance: correlation of allelic frequency to resistance level in wild and laboratory populations of horn flies (Haematobia irritans)

The kdr and super-kdr point mutations found in the insect sodium channel gene are postulated to confer knockdown resistance (kdr) to pyrethroids. Using an allele-specific PCR assay to detect these mutations in individual horn flies, Haematobia irritans (L.), we determined the allelic frequency of the kdr and super-kdr mutations in several wild and laboratory populations. Wild populations with very similar allelic frequencies had resistance levels that ranged widely from 3- to 18-fold relative to a susceptible population. Conversely, the kdr allele frequency in a lab population with 17-fold resistance was nearly double that found in a heavily pressured wild population with 18-fold resistance. We conclude that, although the kdr mutation confers significant levels of pyrethroid resistance, a substantial component of resistance in insecticidally pressured populations is conferred by mechanisms that are PBO-suppressible. High super-kdr allele frequencies were detected in two resistant lab populations, but in wild populations with equivalent resistance the super-kdr allele frequency was very low. Interestingly, in over 1200 individuals assayed, the super-kdr mutation was never detected in the absence of the kdr mutation.     

Protein-nucleic acid interactions in bacteriophage phi 29 DNA replication

phi 29 DNA replication starts at both DNA ends by a protein priming mechanism. The formation of the terminal protein-dAMP initiation complex is directed by the second nucleotide from the 3' end of the template. The transition from protein-primed initiation to normal DNA elongation has been proposed to occur by a sliding-back mechanism that is necessary for maintaining the sequences at the phi 29 DNA ends. Structure-function studies have been carried out in the phi 29 DNA polymerase. By site-directed mutagenesis of amino acids conserved among distantly related DNA polymerases we have shown that the N-terminal domain of phi 29 DNA polymerase contains the 3'-5' exonuclease activity and the strand-displacement capacity, whereas the C-terminal domain contains the synthetic activities (protein-primed initiation and DNA polymerization). Viral protein p6 stimulates the initiation of phi 29 DNA replication. The structure of the protein p6-DNA complex has been determined, as well as the main signals at the phi 29 DNA ends recognized by protein p6. The DNA binding domain of protein p6 has been studied. The results indicate that an alpha-helical structure located in the N-terminal region of protein p6 is involved in DNA binding through the minor groove. The phi 29 protein p5 is the single-stranded DNA binding (SSB) protein involved in phi 29 DNA replication, by binding to the displaced single-stranded DNA (ssDNA) in the replication intermediates. In addition, protein p5 is able to unwind duplex DNA. The properties of the phi 29 SSB-ssDNA complex are described. Using the four viral proteins, terminal protein, DNA polymerase, protein p6 and the SSB protein, it was possible to amplify the 19,285-bp phi 29 DNA molecule by a factor of 4000 after 1 h of incubation at 30 degrees C. The infectivity of the in vitro amplified DNA was identical to that of phi 29 DNA obtained from virions.     

Characterization of synthetic hydrocalumite-type [Ca2Al(OH)6]NO3·mH2O: Effect of the calcination temperature

A lamellar hydrocalumite-type [Ca₂Al(OH)₆]NO₃·mH₂O, (HC), was synthesized and characterized by X-ray diffraction analysis (XRD), surface area, pore size measurements, CO₂-Thermal Programmed Desorption, and later tested as catalysts in the double bond isomerization of 1-butene. The layered structure of HC collapses above 523 K yielding an amorphous material at 573 K which upon calcination at 873–973 K transforms into a mixture of CaO and mayenite Ca₁₂Al₁₄O₃₃. The calcination temperature has a marked effect in the formation of basic sites. Thus for example, HC calcined at 1073 K shows 90% of strong basic sites (CO₂ desorption at 1023 K) while they are absent in HC calcined at 573–673 K. HC calcined at 973 K shows high catalytic activity (74% conversion) in the isomerization of 1-butene without any appreciable deactivation after 4 h on stream.     

Optimization of an industrial DC magnetron sputtering process for graded composition solar thermal absorbing layer

Optimization of an industrial DC magnetron sputtering process for thin graded index coatings for solar thermal absorbers is reported. The optimization concerned the main processing parameters: sputtering power, argon flow, oxygen flow, and system set-up for graded control. The purpose of the optimization was to achieve a surface with efficient solar-thermal energy conversion based on the concept graded index coating, using a metal-dielectric composite coating of nickel–nickel oxide with a continuous change in composition through the film depth profile. It was found that the optimization of the materials composition could be controlled by one parameter related to the sputtering process, the relative oxygen flow RO, defined as the ratio of applied oxygen flow to the critical oxygen flow. For optimized sputtering conditions a solar absorptance of 0.92 was obtained for a single graded index coating on aluminum for RO value of 0.8. From the materials characterization it was found that this gave a graded index coating of two thick sub-layers, a top layer of nano-sized nickel oxide grains and a base layer of nano-size metallic nickel grains with a very thin interface of a mixture of nickel and nickel oxide that was almost amorphous.     

Us without them: Evidence for an intragroup origin of positive in-group regard.

Four experiments examined whether group formation and positive in-group regard require interaggregate comparison as the in-group-requires-an-out-group assumption of the metacontrast principle implies. The authors fostered novel social aggregates with or without a contrasting aggregate with which members could compare and varied intra-aggregate factors (interaction or interdependence). Regardless of whether interaggregate comparison was feasible, the intra-aggregate factors increased the perceived entitativity of the aggregate and positive regard toward the aggregate (i.e., social attraction and cooperation among members). Mediation analyses were consistent with the possibility that the intra-aggregate factors promoted entitativity, which in turn promoted in-group regard. These data suggest that group formation and in-group regard have intragroup origins and do not require comparison with a contrasting social aggregate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual map‐less navigation based on homographies

We introduce a method for autonomous robot navigation based on homographies computed between the current image and images taken in a previous teaching phase with a monocular vision system. The features used to estimate the homography are vertical lines automatically extracted and matched. From homography, the underlying motion correction between the reference path and the current robot location is computed. The proposed method, which uses a sole calibration parameter, has turned out to be especially useful to correct heading and lateral displacement, which are critical in systems based on odometry. We have tested the proposal in simulation, and with real images. Besides, the visual system has been integrated into an autonomous wheelchair for handicapped, working in real time with robustness. © 2005 Wiley Periodicals, Inc.     

Intramedullary cysticercosis cured with drug treatment. A case report

STUDY DESIGN: A report of a patient with cervical intramedullary cysticercosis is presented. OBJECTIVES: To report the first case of intramedullary. cysticercosis cured with drug management only, which supports the hypothesis that management with anthelmintics might be successfully used in this form of cysticercosis. SUMMARY OF BACKGROUND DATA: Intramedullary cysticercosis is a rare manifestation of neurocysticercosis. Every treated patient reported to date has undergone surgery, frequently necessary for diagnosis. Since the anthelmintics praziquantel and albendazole were shown to be effective in parenchymal brain cysticercosis, these drugs have been considered potentially useful in patients with intramedullary cysticercosis. Nevertheless, no case yet had been reported to be cared with only medical therapy. METHODS: The treatment of a patient who suffered multiple cysticercal reinfestations of the nervous system is presented. RESULTS: The patient received prolonged treatment with albendazole because of superimposed cerebral reinfestations. During this treatment, she suffered acute paraparesis, and cervical magnetic resonance imaging showed cyst-like lesions with linear gadolinium enhancement and perilesional edema, indicative of dying cysticerci and inflammatory host reaction. Dexamethasone was added, and progressive neurologic improvement followed with complete resolution of intramedullary lesions. CONCLUSIONS: A preoperative diagnostic suspicion of cysticercosis is important in patients with intramedullary cystic lesions because specific drug treatment is available. Treatment with anthelmintics, particularly albendazole, should be considered in patients with intramedullary cysticercosis before surgery. Corticosteroids may be added to the therapeutic regimen because this may reduce the perilesional edema and prevent neurologic deterioration during the course of anthelmintic treatment.