Vector competence of Culicoides bolitinos and C. imicola for South African bluetongue virus serotypes 1, 3 and 4

Abstract .The susceptibility of field-collected Culicoides bolitinos to infection by oral ingestion of bluetongue virus serotypes 1, 3 and 4 (BLU 1, 3 and 4) was compared with that of field-collected C. imicola and laboratory reared C. variipennis sonorensis . The concentration of the virus per millilitre of bloodmeal was 10^5.0 and 10^6.0TCID₅₀ for BLU 4 and 10^7.2TCID₅₀ for BLU 1 and 3. Of 4927 C. bolitinos and 9585 C. imicola fed, 386 and 287 individual midges survived 10 days extrinsic incubation, respectively. Midges were assayed for the presence of virus using a microtitration assay on BHK-21 cells and/or an antigen capture ELISA. Infection prevalences for the different serotypes as determined by virus isolation ranged from 22.7 to 82.0% in C. bolitinos and from 1.9 to 9.8% in C. imicola; infection prevalences were highest for BLU 1, and lowest for BLU 4 in both species. The mean log₁₀ TCID₅₀ titre of the three BLU viruses per single fly was higher in C. bolitinos than in C. imicola . The results suggested that C. bolitinos populations are capable vectors of the BLU viruses in South Africa. A high correlation was found between virus isolation and ELISA results for the detection of BLU 1, and less for BLU 4; the ELISA failed to detect the presence of BLU 3 in infected flies. The C. v. sonorensis colonies had a significantly lower susceptibility to infection with BLU 1, 3 and 4 than C. bolitinos and C. imicola . However, since infection prevalence of C. v. sonorensis was determined only by ELISA, this finding may merely reflect the insensitivity of this assay at low virus titres, compared to virus isolation.     

Antitumour activities of levans produced by Zymomonas mobilis strains

Levans produced by four Zymomonas mobilis strains showed antitumour activity against sarcoma 180 and Ehrlich carcinoma in Swiss albino mice. Levans from two strains (ZAP and CP4) had the highest effects. NMR analysis showed that the polymers were composed only of fructose units. The results suggested that the antineoplasic effect is associated to the polysaccharide molecular weight and that a particular molecular weight range may be responsible for this effect.     

Successful transfer of embryos recovered from a cow with chronic cervicitis of mixed aerobic and anaerobic bacterial aetiology a case report

An imported 13-year-old Simmentaler cow was presented with severe purulent cervicitis and endometritis from which Corynebacterium pyogenes , Fusobacterium necrophorum , Bacteroides melaninogenicus and an untyped Clostridium perfringens were isolated. The endometritis responded to treatment but the cervix did not and remained fibrous, continuously patent and purulent. Natural pregnancy was considered unlikely and the cow was prepared as an embryo transfer donor. Eight embryos were recovered and six transferred, resulting in five confirmed pregnancies and four live births.     

Practical activation and retention of locomotion constraints in neuromusculoskeletal control system models

Two approaches are discussed in the treatment of locomotion constraints in neuromusculoskeletal control system models: (i) the modelling of viscoelastic environmental contact points to avoid the impact problem, and the subsequent reduction of the state-space dimension by elimination of superfluous generalized coordinates; and (ii) the computation of instantaneous velocity changes occurring during the impact, and the subsequent computation of constraint forces which are such that the constraints remain satisfied for the period of their retention. It is shown that the latter approach is computationally more efficient. Detailed algorithms are presented and their implementation is demonstrated by an example.     

Differential effect of temperature on mitrochondrial activity in shoots from freshly harvested and moderately aged kernels of maize (Zea mays L.)

This paper reports on a study of mitochondrial activity in etiolated shoots of freshly harvested and moderately aged kernels of maize. Activity was investigated after incubation at a favourable temperature (25°C), sub-optimal temperature (13°C) and after a heat shock (46°C for 2h). Although impaired mitochondrial activity in shoots from moderately aged maize kernels was not detected at 25°C, deficiencies became evident under low temperature stress (13°C). State 3 oxygen uptake, cyanide-insensitive oxygen uptake and cytochrome oxidase activity were lower in mitochondria from these shoots at 13°C than in mitochondria from shoots of freshly harvested kernels at this temperature. After a heat shock, cyanide-insensitive oxygen uptake was higher, and cytochrome oxidase activity lower, in shoots of aged kernels than in shoots of fresh kernels. No significant differences in ADP: O ratio or succinate dehydrogenase activity occurred between mitochondria from shoots of the two seed lots in any of the temperature treatments.     

Metagenomic Exploration of Viruses throughout the Indian Ocean

The characterization of global marine microbial taxonomic and functional diversity is a primary goal of the Global Ocean Sampling Expedition. As part of this study, 19 water samples were collected aboard the Sorcerer II sailing vessel from the southern Indian Ocean in an effort to more thoroughly understand the lifestyle strategies of the microbial inhabitants of this ultra-oligotrophic region. No investigations of whole virioplankton assemblages have been conducted on waters collected from the Indian Ocean or across multiple size fractions thus far. Therefore, the goals of this study were to examine the effect of size fractionation on viral consortia structure and function and understand the diversity and functional potential of the Indian Ocean virome. Five samples were selected for comprehensive metagenomic exploration; and sequencing was performed on the microbes captured on 3.0-, 0.8- and 0.1 µm membrane filters as well as the viral fraction (<0.1 µm). Phylogenetic approaches were also used to identify predicted proteins of viral origin in the larger fractions of data from all Indian Ocean samples, which were included in subsequent metagenomic analyses. Taxonomic profiling of viral sequences suggested that size fractionation of marine microbial communities enriches for specific groups of viruses within the different size classes and functional characterization further substantiated this observation. Functional analyses also revealed a relative enrichment for metabolic proteins of viral origin that potentially reflect the physiological condition of host cells in the Indian Ocean including those involved in nitrogen metabolism and oxidative phosphorylation. A novel classification method, MGTAXA, was used to assess virus-host relationships in the Indian Ocean by predicting the taxonomy of putative host genera, with Prochlorococcus, Acanthochlois and members of the SAR86 cluster comprising the most abundant predictions. This is the first study to holistically explore virioplankton dynamics across multiple size classes and provides unprecedented insight into virus diversity, metabolic potential and virus-host interactions.     

Purification and properties of the Escherichia coli nucleoside transporter NupG, a paradigm for a major facilitator transporter sub-family

NupG from Escherichia coli is the archetype of a family of nucleoside transporters found in several eubacterial groups and has distant homologues in eukaryotes, including man. To facilitate investigation of its molecular mechanism, we developed methods for expressing an oligohistidine-tagged form of NupG both at high levels (>20% of the inner membrane protein) in E. coli and in Xenopus laevis oocytes. In E. coli recombinant NupG transported purine (adenosine) and pyrimidine (uridine) nucleosides with apparent K(m) values of approximately 20-30 microM and transport was energized primarily by the membrane potential component of the proton motive force. Competition experiments in E. coli and measurements of uptake in oocytes confirmed that NupG was a broad-specificity transporter of purine and pyrimidine nucleosides. Importantly, using high-level expression in E. coli and magic-angle spinning cross-polarization solid-state nuclear magnetic resonance, we have for the first time been able directly to measure the binding of the permeant ([1'-(13)C]uridine) to the protein and to assess its relative mobility within the binding site, under non-energized conditions. Purification of over-expressed NupG to near homogeneity by metal chelate affinity chromatography, with retention of transport function in reconstitution assays, was also achieved. Fourier transform infrared and circular dichroism spectroscopy provided further evidence that the purified protein retained its 3D conformation and was predominantly alpha-helical in nature, consistent with a proposed structure containing 12 transmembrane helices. These findings open the way to elucidating the molecular mechanism of transport in this key family of membrane transporters.     

A novel oxylipin-associated ‘ghosting’ phenomenon in yeast flocculation

Research on the distribution of oxylipins (3-hydroxy fatty acids) in flocculant strains of the yeast Saccharomyces cerevisiae led to the uncovering of a novel ghosting phenomenon observed during assumed lectin-mediated aggregation. We found that intracellular oxylipin-containing osmiophilic layers migrate through yeast cell walls in a ghostlike fashion without visually affecting the cell wall structure or the layers. This migration resulted in the binding of these layers to cell walls of adjacent cells. Consequently, ghosting seems a prerequisite for flocculation to occur. However, ghosting alone may not be sufficient to ensure flocculation.     

Effects of long-term fixation on histological quality of undecalcified murine bones embedded in methylmethacrylate

While long-term fixation and storage of specimens is common and useful for many research projects, it is particularly important for space flight investigations where samples may not be returned to Earth for several months (International Space Station) or years (manned mission to Mars). We examined two critical challenges of space flight experimentation: the effect of long-term fixation on the quality of mouse bone preservation and the preservation of antigens and enzymes for both histochemical and immunohistochemical analyses, and how the animal/sample processing affects the preservation. We show that long-term fixation minimally affects standard histological staining, but that enzyme histochemistry and immunolabeling are greatly compromised. Further, we demonstrate that whole animal preservation is not as suitable as whole leg or stripped leg preservation for long-term fixation and all histological analyses. Overall, we recommend whole leg processing for long-term storage of bone specimens in fixative prior to embedding in plastic for histological examination.     

Factors influencing in the response of <i>Schizolobium parahybum</i> (Vell) Blake to <i>Ceratocystis paradoxa</i> and <i>C. moniliformis</i>

In the Ecuadorian coast one of the most destructive diseases of the pachaco is vascular wilt or stem rot caused by Ceratocystis complex, so the aim of this study was to determine the factors that affect the efficiency of the reaction of bark pachaco to this disease. This research was conducted under laboratory conditions, using trees pachaco S38, S41, S98, AE-1, AE-2 and AE-3, and pathogenic species Ceratocystis paradoxa and C. moniliformis. The method utilized was tissue stem bark,with bark sections with 4.5 cm², and a suspension of 3x10⁴ units infection and remained in a humid chamber for 96 hours at 25 ± 5 °C. Were determined grades of resistance/ susceptibility using a scale from 0 to 4, depending on the amount of mycelia and peritecio in each plant sample. Three factors were used: four colonies obtained by several transfers from each fungal specie, four ages of colonies of each fungal specie and four volumes of inoculum applied (units of infection), using for each experiment separately Completely Randomized Design with 4 replications factorial arrangement. For comparison between treatment means was used Tukey test at 5% probability of error. For future trials using this technique, you could use 30-day colonies for C. paradoxa and 40 days for C. moniliformis, and an application volume of 100 μL/cm², it would improve the level of response for the formation of perithecium and mycelia in samples cortex.