Search

Large inputs of woody debris to soil can improve the soil. We examined the fate of woody debris buried in soil after fire-free forest conversion to cropland in French Guiana. We measured the mass loss of woody debris > 4 mm on five sampling dates for 4 years after deforestation. Composition of the organic matter of woody debris was analysed with Rock- Eval pyrolysis, which enabled us to distinguish a labile carbon pool ( Clab) and a resistant carbon pool ( Cres). Decomposition of woody debris followed a first-order function with a half-life of 17.6 months. During the decomposition of woody debris > 4 mm, the C: N ratio, hydrogen index ( HI) and pyrolysed carbon below 400°C ( R400) decreased, suggesting that decarboxylation and dehydrogenation of woody debris occurred. Both Clab and Cres stocks decreased with time, but the decrease in Clab was faster. There was little humification of the debris and no long-term biogeochemical preservation of a woody debris fraction, which accords with the first-order decay observed. We conclude that the benefits of ligno-cellulosic inputs for soil organic carbon contents in a tropical humid climate occur during the first year following deforestation. Résumé Les apports massifs de débris de bois au sol peuvent améliorer le sol. Nous avons examiné sur un site en Guyane le devenir de débris de bois enfouis dans le sol, suite à la conversion sans brûlis de forêt en cultures. Nous avons mesuré le stock des débris de bois > 4 mm jusqu'à 4 années après déforestation. Les transformations de la matière organique des débris ont bois ont été analysées par la pyrolyse Rock- Eval, nous permettant de distinguer un compartiment de carbone labile ( Clab) et un compartiment de carbone résistant ( Cres) dans ces débris. La décomposition des débris de bois suit une décroissance exponentielle de premier ordre, avec une demi-vie de 17,6 mois. Durant la décomposition des débris, le rapport C/ N, l'indice d'hydrogène ( HI) et le carbone pyrolysé avant 400°C ( R400) diminuent, suggérant des processus de décarboxylation et déshydrogénation qui se mettent en place rapidement après l'enfouissement des débris. Les stocks de Clab et Cres diminuent tous deux au cours du temps, avec une cinétique plus rapide pour Clab. Ces résultats indiquent une faible polymérisation de la matière organique des débris, et une absence de préservation biogéochimique d'une partie des débris, en accord avec la décroissance exponentielle observée. Cette étude suggère que les bénéfices des amendements ligno-cellulosiques pour la matière organique des sols sont de courte durée en milieu tropical humide. [ABSTRACT FROM AUTHOR]

The effectiveness of a newly developed lamellar settler was confirmed by onsite experiments. The device had inclined parallel plates arranged in a vertical direction in a settling tank. This vertical arrangement method enables many more plates to be set compared to the conventional horizontal arrangement. As an original and distinctive innovation, both the right and left edges of the plates were closed, for removing the clear water between the plates, The tube settler modules were installed in a final settling tank of a sewage treatment plant. Tests conducted over a 9 months period showed that the system operated successfully and under normal operation conditions, the new device could treat almost the same flow rate as that treated by a conventional tank, 5,000m³/day. For storm water, the new tube settler was demonstrated to enhance the settling tank capacity by up to 3 times. [ABSTRACT FROM AUTHOR]

A three-dimensional (3D) internal structure observation system based on serial sectioning was developed from an ultrasonic elliptical vibration cutting device and an optical microscope combined with a high-precision positioning device. For bearing steel samples, the cutting device created mirrored surfaces suitable for optical metallography, even for long-cutting distances during serial sectioning of these ferrous materials. Serial sectioning progressed automatically by means of numerical control. The system was used to observe inclusions in steel materials on a scale of several tens of micrometers. Three specimens containing inclusions were prepared from bearing steels. These inclusions could be detected as two-dimensional (2D) sectional images with resolution better than 1 μm. A three-dimensional (3D) model of each inclusion was reconstructed from the 2D serial images. The microscopic 3D models had sharp edges and complicated surfaces. [ABSTRACT FROM AUTHOR]

We study the influence of atmospheric turbulence on satellite communications by the theoretical analysis of propagation characteristics of electromagnetic waves through inhomogeneous random media. The analysis is done by using the moment of wave fields given on the basis of a multiple scattering method. We analyze the bit error rate (BER) using the average received intensity or power for the Geostationary Earth Orbit (GEO) satellite communications in Ka-band at low elevation angles under atmospheric turbulence whose statistical characteristics are given by the Kolmogorov model. From the analysis, the degradation in BER for the uplink is found to be caused by the decrease in the average received intensity due to spot dancing and wave form distortion of wave beams; on the other hand, for the downlink, the degradation in BER is caused by the decrease in the spatial coherence of received waves. [ABSTRACT FROM AUTHOR]

Seasonal changes in resource investment into individual offspring are well documented, but no attention has been paid to the allocation of the invested resource among the body parts of the offspring. In the present study, seasonal changes in the absolute and relative sizes in a spiderling of the wolf spider Pardosa pseudoannulata Boes. et Str. are investigated, and the relationship between spiderling body size and the ability to moult during a food shortage is clarified. Spiderlings that emerge in November have a significantly larger cephalothorax and abdomen than those that emerge in June. In addition, the abdomen–cephalothorax size ratio is significantly greater in November than in June offspring. Under limited food availability conditions, only 40% of spiderlings moult. Nymphs that do moult have a significantly larger cephalothorax, abdomen and abdomen–cephalothorax size ratio than nymphs that do not moult. Thus, both the quantity of resources invested in the cephalothorax and abdomen of a spiderling and the proportional allocation of resources between the two body parts change seasonally in Pa. pseudoannulata; alteration of the resource allocation occurs in late autumn. Larger spiderlings of Pa. pseudoannulata that emerge in late autumn would be able to develop into advanced instars even during food shortage, and therefore may have better overwintering survival rates. [ABSTRACT FROM AUTHOR]

Cassia yellow blotch virus (CYBV), genus Bromovirus, was isolated from the Australian native legume, Cassia pleurocarpa, in western Queensland, and its host range was found to be distinct from other bromoviruses. In this study, CYBV was shown to infect systemically and efficiently a model plant species, Arabidopsis thaliana, as we recently reported for another bromovirus, Spring beauty latent virus (SBLV). We constructed full-length cDNA clones of CYBV genomic RNAs from which infectious in vitro transcripts can be transcribed, and determined their complete nucleotide sequences. CYBV RNA3 contains the box B motif in the intercistronic region, but lacks the subgenomic promoter-like sequence in the 5′ noncoding region, as does Brome mosaic virus (BMV). To understand relationships among bromoviruses, we generated reassortants between CYBV and three other bromoviruses, BMV, SBLV and Cowpea chlorotic mottle virus. We found that all reassortants between BMV and CYBV accumulated viral RNAs to detectable levels in protoplasts of Nicotiana benthamiana, even when RNAs 1 and 2, which encode the replication proteins 1a and 2a, respectively, were heterologous. Sequence comparison and reassortment experiments of CYBV and other bromoviruses demonstrated that CYBV is closely related to BMV. [ABSTRACT FROM AUTHOR]

This paper deals with turbidity currents in a circular settling tank. A mathematical model with a k-ε turbulence model has been developed. Using this mathematical model, the following unique properties of turbidity currents in a circular settling tank are demonstrated: turbulence induced by the turbidity currents remains after most sediment particles have settled down. This residual turbulent diffusivity has a serious effect on the settling of finer particles. This phenomenon is a very important result in this study. Especially, the case of a smaller densimetric Froude number, which is a stronger density effect, this residual turbulence effect increases, and also decreases the removal ratio in the downstream with low concentration. Generally, the bottom density current enhances the sediment transport near the tank bottom, while the bottom shear gives reversal influence. When the settling velocity is high, the settling ends under the developing stage both of the turbidity current and of the bottom boundary layer. On the contrary, if the settling velocity is low, the sediment travels a long distance, where the boundary layer is built up, resulting in the reduction of sediment transport near the tank bottom. The overall properties of the density-affected settling tank are also investigated in terms of the removal ratio. [ABSTRACT FROM AUTHOR]

Presents a mathematical model that describes a batch flotation process. How the model employed a similar method to the hindered settling of flocculated material; Basis of the idea being that the time growth curves of separated liquor zone showed a similar character to the settling curve of flocculated material, when the vertical axis reversed.

Examines the bit error rate in a Ka-band satellite communications. Calculation of the bit error rate under the arrival-angle fluctuations of microwave beams in a propagated atmospheric turbulent media; Relation of the atmospheric turbulence (AT) with the degree of bit error at low elevation angles; Effect of the Kolmogorov model of AT on the bit error rate.

To depress the vibration and meandering of a thin steel plate in a steel making plant, electromagnets are applied to the plate. According to the results of numerical calculation, the different pole arrangement is superior to the same pole arrangement for the vertical position control, though the same pole arrangement is superior to the different pole arrangement for the lateral position control. There is no significant difference in the electromagnetic forces obtained at room temperature as compared to 700/spl deg/C. However, the investigation shows that the smallest electromagnetic forces are obtained at the 765/spl deg/C. [ABSTRACT FROM PUBLISHER]

Presented are the fade duration dynamics as observed in four close stations. Fade duration statistics derived from the collected received signal during a critical period in the region are presented and analysed. The obtained results are compared with the model release by the ITU-R P.1623 recommendation. Some modifications are then proposed. [ABSTRACT FROM AUTHOR]

Studies the effects of rainfall on Ku-band satellite channels. Use of the JCSAT-1B satellite and several very small aperture terminals installed at different locations; Worst month and yearly distribution of Ku-band rain attenuation.

In this study, we examined the role of nitric oxide (NO) in controlling vascular integrity mediated by vascular endothelial (VE)-cadherin in chronic inflammation. Periapical granulomas were analysed for the expression of inducible NO synthase (iNOS) and VE-cadherin, and more iNOS expression than VE-cadherin was shown. Human umbilical vein endothelial cells (HUVECs) were stimulated with proinflammatory cytokines and lipopolysaccharide extracted from Porphyromonas gingivalis and it induced iNOS expression, whereas it reduced VE-cadherin expression, compared with negative controls. On the other hand, pre-incubation with 1400W, an iNOS-specific inhibitor, markedly reduced iNOS expression in stimulated HUVECs and restored VE-cadherin expression to its control level, suggesting that vascular integrity was modulated in conjunction with the reduction of NO. Immunocytochemistry confirmed the functional role of NO in cultured HUVEC monolayers with or without 1400W. These data are consistent with a hypothesis suggesting that NO could attenuate VE-cadherin-mediated vascular integrity in human chronic inflammation. [ABSTRACT FROM AUTHOR]

A fatal case of late-onset graft infection of the thoracic aorta due to group C beta-hemolytic streptococcus is described. A 37-year-old male patient, who had a history of total aortic arch replacement for acute aortic dissection 8 years before, was admitted to the department. He suffered from toxic shock syndrome, disseminated intravascular coagulation (DIC), and acute renal failure. Group C beta-hemolytic streptococcus was detected from his blood; however, echocardiography, computed tomography (CT), and magnetic resonance imaging (MRI) failed to detect the focus of the infection. In spite of intensive care, including antibiotic therapy, artificial ventilation, and continuous hemodiafiltration, he died on the 18th day of hospitalization. Autopsy revealed that a small abscess was present at the proximal anastomotic segments of the patient's graft. A bite inflicted by his dog, 14 days before admission, was suspected to be the source of this bacterium. A rare case of graft infection of thoracic aorta in terms of causative organism, long period from graft replacement to graft infection, and site of infection is presented and discussed. [ABSTRACT FROM AUTHOR]

Ticks are obligate haematophagous arthropods that feed on vertebrate blood containing high levels of iron. The host-derived iron reacts to oxygen in the tick's body, and then high levels of reactive oxygen species, including hydrogen peroxide (H2O2), may be generated. High levels of H2O2 cause oxidative stress to aerobic organisms. Therefore, antioxidant responses are necessary to control H2O2. We focused on peroxiredoxins (Prxs), H2O2-scavenging enzymes. The sequence of Haemaphysalis longicornis 2-Cys Prx (HlPrx2) was identified from fat body cDNA libraries of this tick and recombinant HlPrx2 was then pre- pared using Escherichia coli. By comparison with the 2-Cys Prxs of other organisms, we found two conserved cysteines in HlPrx2, Cys51 and Cys172. We examined the antioxidant activity of HlPrx2 and mutant proteins produced by a single base substitution, converting one or both of these cysteines into serines. The assays revealed that proteins containing Cys51 showed antioxidant activity when H2O2 was removed. Sodium dodecyl sulphate polyacrylamide gel electrophoresis and size-exclusion chromatography demonstrated that only the wild-type HlPrx2 formed homodimers and that all of the proteins that we made had a high molecular weight peak. These results indicate that both Cys51 and Cys172 are essential for the dimerization of HlPrx2, whereas only the Cys51 residue is necessary for antioxidant activity. [ABSTRACT FROM AUTHOR]

Anaerobic ammonium oxidation (anammox) is a novel nitrogen pathway catalyzed by anammox bacteria which are obligate anaerobic chemoautotrophs. In this study, enrichment culture of marine anammox bacteria (MAAOB) from the samples related to seawater was conducted. Simultaneous removal of ammonium and nitrite was confirmed in continuous culture inoculated with sediment of a sea-based waste disposal site within 50 days. However, no simultaneous nitrogen removal was observed in cultures inoculated with seawater-acclimated denitrifying sludge or with muddy sediment of tideland even during 200 days. Nitrogen removal rate of 0.13 kg/m³/day was achieved at nitrogen loading rate of 0.16 kg/m³/day after 320th days in the culture inoculated with the sediment of waste disposal site. The nitrogen removal ratio between ammonium nitrogen and nitrite nitrogen was 1:1.07. Denaturing gradient gel electrophoresis (DGGE) analysis indicated that an abundance of the bacteria close to MAAOB and coexistence of ammonium oxidizing bacteria and denitrifying bacteria in the culture. [ABSTRACT FROM AUTHOR]

Serological immunoscreening was used to identify a gene encoding heat shock protein-70 from Babesia gibsoni (BgHSP-70) that showed high homology with HSP-70s from other apicomplexan parasites. This gene corresponded to a full-length cDNA containing an open reading frame of 1968 bp predicted to result in a 70-kDa mature protein consisting of 656 amino acids. Analysis of the expression levels of BgHSP-70 indicated elevated transcription from cultured parasites incubated at 40°C for 1 h, but not at 30°C. Interestingly, antiserum raised against recombinant BgHSP-70 protein reacted specifically not only with a 70-kDa protein of B. gibsoni but also with a corresponding native protein of B. microti (BmHSP-70), indicating the high degree of conservation of this protein. The BmHSP-70 gene was then isolated and characterized and the immunoprotective properties of recombinant BgHSP-70 (rBgHSP-70) and rBmHSP-70 were compared in vitro and in vivo. Both proteins had potent mitogenic effects on murine and canine mononuclear cells as evidenced by high proliferative responses and IFN-γ production after stimulation. Immunization regimes in BALB/c and C57BL/6 mice using rBgHSP-70 and rBmHSP-70 elicited high antibody levels, with concurrent significant reductions in peripheral parasitaemias. Taken together, these results emphasize the potential of HSP-70s as a molecular adjuvant vaccine. [ABSTRACT FROM AUTHOR]

We have studied the impact of complement component 3 (C3) deficiency on the progression of lethal Babesia rodhaini infection in immune mice. A B. gibsoni ribosomal phosphoprotein P0 (BgP0) previously reported to be a cross-protective antigen against Babesia infection was used to immunize C57BL/6 wild-type (WT) and C3-deficient (C3–/–) mice. Test mice were immunized intraperitoneally (i.p.) with recombinant BgP0 (rBgP0), while controls either were immunized with PBS or did not receive any immunization. Following the immunization regime, test WT mice induced a specifically strong humoral response consisting of mixed immunoglobulins IgG1 and IgG2 associated with high production of IFN-γ in the supernatant of splenocytes. While test C3–/– mice had significantly decreased total IgG, IgG1 and IgG2b responses, the secretions of IL-12 and IFN-γ tended to be lower than those in WT mice. Furthermore, partial protection was only observed in rBgP0-immunized WT mice but not in C3–/– mice or controls. Indeed, rBgP0-immunized WT mice showed significant reductions in the initiation of parasitaemia correlated with delayed mortalities and considerable survival rates. Taken together, our results indicate that cross-protection was impaired in C3–/– mice in view of the decrease in the antibody responses and cytokine production and the high susceptibility to infection. [ABSTRACT FROM AUTHOR]

In the present study, 19 monoclonal antibodies (mAbs) against adult Ornithodoros moubata hemocytes were established, and the reactivity of the hemocytes to these mAbs was examined by an indirect fluorescent antibody test (IFAT), Western blot and immunoprecipitation analyses. It was shown that the reactivities of the hemocytes to the mAbs varied among morphologically similar hemocyte types, and most mAbs produced in the present study showed the multiple band reactivity. However, the presence of shared epitopes among peptide subunits of the same protein or entirely different proteins are not common, so their reactivity could not be explained in detail. These results suggest that there are morphologically similar but functionally differentiated hemocytes. Therefore, in addition to morphological classification, the molecular-based classification of the hemocytes is also required. In order to assess the lethal effect of blood meal containing each mAb, artificial feeding was performed. The OmHC 31 showed the strongest lethal effect on adult female O. moubata. In conclusion, anti-hemocyte mAbs produced in this study are useful not only for the immunological classification of hemocytes but also for the immunological control of the tick. [Copyright &y& Elsevier]

AbstractAntioxidant enzymes in eukaryotes play an important role in protection against the oxygen radicals generated during aerobic metabolism. Here we report the cloning and characterization of a cDNA encoding the antioxidant enzyme peroxiredoxin from the hard tick Haemaphysalis longicornis (HlPrx). HlPrx is 939 bp long and contains a 101 bp non-translated sequence at the 5′ end and a polyadenylation singnal followed by a poly(A) tail at the 3′ end. HlPrx encodes a full-length protein with a predicted molecular mass of 26 kDa that possesses one cysteine residue at amino acid 49 that is conserved among Prx proteins of various species. GenBank™ analysis showed that the deduced amino acid sequence had significant similarity to mammalian and plant Prxs at the amino acid level. A DNA-nicking assay revealed that Escherichia coli–expressed recombinant HlPrx (rHlPrx) inhibited oxidative-nicking of supercoiled plasmid DNA. Two-dimensional immunoblot analysis with mouse antirHlPrx serum showed reaction with a major constituent protein spot in extracts of adult ticks. In addition, immunoblot analysis showed that rHlPrx was immunoreacted with serum from rabbits repeatedly infested with H. longicornis. Localization analysis using mouse antirHlPrx serum revealed that native HlPrx was highly expressed in the salivary gland of the tick. Moreover, Northern blot analysis showed that the level of HlPrx transcripts was increased during blood sucking. The present results indicate that HlPrx may be an important detoxifying enzyme during the normal life span as well as during blood sucking in ticks. [ABSTRACT FROM AUTHOR]

The hepatitis C virus (HCV) RNA-dependent RNA polymerase (RdRp) has been proposed to change conformations in association with RNA synthesis and to interact with cellular proteins. In vitro, the RdRp can initiate de novo from the ends of single-stranded RNA or extend a primed RNA template. The interactions between the Δ 1 loop and thumb domain in NS5B are required for de novo initiation, although it is unclear whether these interactions are within an NS5B monomer or are part of a higher-order NS5B oligomeric complex. This work seeks to address how polymerase conformation and/or oligomerization affects de novo initiation. We have shown that an increasing enzyme concentration increases de novo initiation by the genotype 1b and 2a RdRps while primer extension reactions are not affected or inhibited under similar conditions. Initiation-defective mutants of the HCV polymerase can increase de novo initiation by the wild-type (WT) polymerase. GTP was also found to stimulate de novo initiation. Our results support a model in which the de novo initiation-competent conformation of the RdRp is stimulated by oligomeric contacts between individual subunits. Using electron microscopy and single-molecule reconstruction, we attempted to visualize the low-resolution conformations of a dimer of a de novo initiation-competent HCV RdRp. [ABSTRACT FROM AUTHOR]