Phenobarbital: a locus of action on spike broadening and potassium inactivation

1. The effect of phenobarbital on frequency-dependent spike broadening and potassium inactivation was studied in snail neurons. 2. The amount of spike broadening was significantly depressed by the application of 10(-3) M phenobarbital but the time course of broadening was unaffected. 3. In voltage clamped neurons, this concentration of phenobarbital significantly depressed the amount of potassium current inactivation without altering its time constant. 4. A possible locus of phenobarbital's anticonvulsant action is through a decrease in synaptic efficacy resulting from a depression of presynaptic spike broadening.     

Biocides formulation of essential oils having antimicrobial activity

Essential oils of fennel, peppermint, caraway, eucalyptus, geranium and lemon were tested for their antimicrobial activities against some plant pathogenic micro-organisms (Fusarium oxysporum, Alternaria alternate, Penicilium italicum Penicilium digitatum and Botyritus cinerea). Essential oils of fennel, peppermint, caraway were selected as an active ingredient for the formulation of biocides due to their efficiency in controlling the tested micro-organisms. Successful emulsifiable concentrates (biocides) were prepared from these oils using different emulsifiers (Emulgator B.L.M. Tween20 and Tween80) and different fixed oils (sesame, olive, cotton and soybean oils). Physico-chemical properties of the formulated biocide (spontaneous emulsification, emulsion stability test, cold stability and heat stability tests as well as viscosity, surface tension and pH) were measured. The prepared biocides were ready to be tested for application in a future work as a safe pesticide against different pathogens.     

Germination of <i>Eryngium regnellii</i>: a major species for ecological restoration of plant-pollinator interactions in the Southern Pampas (Buenos Aires,Argentina)

Eryngium regnellii Malme belongs to the largest genera in the Apiaceae family, with 250 species worldwide and 65 represented in South America. It is a herbaceous species typical of hill plant communities, which, along with remnant grassland patches, are the most relevant natural habitats for the maintenance of diversity in the Southern Pampas. Eryngium regnellii is key to the maintenance of pollination mutualisms, being a generalist (displaying a diverse assemblage of pollinators) and ubiquitous species (present in all studied sierras). However, fragmentation of the Pampean landscape due to agricultural intensification has led to the loss of natural environments. Therefore, the reintroduction of E. regnellii in strategic places would facilitate the occurrence of wild pollinators, while favoring pollination services in the agroecosystem. The germination requirements of E. regnellii were studied because a better knowledge of the reproductive biology of this species would provide information relevant to its reproduction and reintroduction into degraded areas. Germination percentages and mean time to germination were evaluated, using one control and two pre-germination treatments: chemical scarification with sulfuric acid, and mechanical scarification with sand paper. Chemical scarified seeds did not germinate. Mechanically scarified and control seed groups showed no significant differences either in germination percentages (49% and 59% respectively) or in mean germination time (13 and 14 days, respectively). Results indicate that E. regnellii shows no physical dormancy, and does not require specific pre-germination treatments for germination under the studied laboratory conditions. The high germination capacity of E. regnellii, along with its ecological attributes, make it a potential species for restoring plant-pollinator interactions in the fragmented landscapes of the Southern Pampas.     

TGF-β1 induced epithelial to mesenchymal transition (EMT) in human bronchial epithelial cells is enhanced by IL-1β but not abrogated by corticosteroids

Background

Chronic persistent asthma is characterized by ongoing airway inflammation and airway remodeling. The processes leading to airway remodeling are poorly understood, and there is increasing evidence that even aggressive anti-inflammatory therapy does not completely prevent this process. We sought to investigate whether TGFβ₁ stimulates bronchial epithelial cells to undergo transition to a mesenchymal phenotype, and whether this transition can be abrogated by corticosteroid treatment or enhanced by the pro-inflammatory cytokine IL-1β.

Methods

BEAS-2B and primary normal human bronchial epithelial cells were stimulated with TGFβ₁ and expression of epithelial and mesenchymal markers assessed by quantitative real-time PCR, immunoblotting, immunofluorescence microscopy and zymography. In some cases the epithelial cells were also incubated with corticosteroids or IL-1β. Results were analyzed using non-parametric statistical tests.

Results

Treatment of BEAS-2B or primary human bronchial epithelial cells with TGFβ₁ significantly reduced the expression level of the epithelial adherence junction protein E-cadherin. TGFβ₁ then markedly induced mesenchymal marker proteins such as collagen I, tenascin C, fibronectin and α-smooth muscle actin mRNA in a dose dependant manner. The process of mesenchymal transition was accompanied by a morphological change towards a more spindle shaped fibroblast cell type with a more motile and invasive phenotype. Corticosteroid pre-treatment did not significantly alter the TGFβ₁ induced transition but IL-1β enhanced the transition.

Conclusion

Our results indicate, that TGFβ₁ can induce mesenchymal transition in the bronchial epithelial cell line and primary cells. Since asthma has been strongly associated with increased expression of TGFβ₁ in the airway, epithelial to mesenchymal transition may contribute to the contractile and fibrotic remodeling process that accompanies chronic asthma.     

Transient receptor potential channel A1 is directly gated by calcium ions

Members of the superfamily of transient receptor potential (TRP) channels are proposed to play important roles in sensory physiology. As an excitatory ion channel TRPA1 is robustly activated by pungent irritants in mustard and garlic and is suggested to mediate the inflammatory actions of environmental irritants and proalgesic agents. Here, we demonstrate that, in addition to pungent natural compounds, Ca(2+) directly gates heterologously expressed TRPA1 in whole-cell and excised-patch recordings with an apparent EC(50) of 905 nm. Pharmacological experiments and site-directed mutagenesis indicate that the N-terminal EF-hand calcium-binding domain of the channel is involved in Ca(2+)-dependent activation. Furthermore, we determine Ca(2+) as prerequisite for icilin activity on TRPA1.     

Therapeutic antibody engineering by high efficiency cell screening

In recent years, several cell-based screening technologies for the isolation of antibodies with prescribed properties emerged. They rely on the multi-copy display of antibodies or antibody fragments on a cell surface in functional form followed by high through put screening and isolation of cell clones that carry an antibody variant with the desired affinity, specificity, and stability. Particularly yeast surface display in combination with high-throughput fluorescence-activated cell sorting has proven successful in the last fifteen years as a very powerful technology that has some advantages over classical generation of monoclonals using the hybridoma technology or bacteriophage-based antibody display and screening. Cell-based screening harbours the benefit of single-cell online and real-time analysis and characterisation of individual library candidates. Moreover, when using eukaryotic expression hosts, intrinsic quality control machineries for proper protein folding and stability exist that allow for co-selection of high-level expression and stability simultaneously to the binding functionality. Recently, promising technologies emerged that directly rely on antibody display on higher eukaryotic cell lines using lentiviral transfection or direct screening on B-cells. The combination of immunisation, B-cell screening and next generation sequencing may open new avenues for the isolation of therapeutic antibodies with prescribed physicochemical and functional characteristics.     

Metagenomic insights into strategies of carbon conservation and unusual sulfur biogeochemistry in a hypersaline Antarctic lake

Organic Lake is a shallow, marine-derived hypersaline lake in the Vestfold Hills, Antarctica that has the highest reported concentration of dimethylsulfide (DMS) in a natural body of water. To determine the composition and functional potential of the microbial community and learn about the unusual sulfur chemistry in Organic Lake, shotgun metagenomics was performed on size-fractionated samples collected along a depth profile. Eucaryal phytoflagellates were the main photosynthetic organisms. Bacteria were dominated by the globally distributed heterotrophic taxa Marinobacter, Roseovarius and Psychroflexus. The dominance of heterotrophic degradation, coupled with low fixation potential, indicates possible net carbon loss. However, abundant marker genes for aerobic anoxygenic phototrophy, sulfur oxidation, rhodopsins and CO oxidation were also linked to the dominant heterotrophic bacteria, and indicate the use of photo- and lithoheterotrophy as mechanisms for conserving organic carbon. Similarly, a high genetic potential for the recycling of nitrogen compounds likely functions to retain fixed nitrogen in the lake. Dimethylsulfoniopropionate (DMSP) lyase genes were abundant, indicating that DMSP is a significant carbon and energy source. Unlike marine environments, DMSP demethylases were less abundant, indicating that DMSP cleavage is the likely source of high DMS concentration. DMSP cleavage, carbon mixotrophy (photoheterotrophy and lithoheterotrophy) and nitrogen remineralization by dominant Organic Lake bacteria are potentially important adaptations to nutrient constraints. In particular, carbon mixotrophy relieves the extent of carbon oxidation for energy production, allowing more carbon to be used for biosynthetic processes. The study sheds light on how the microbial community has adapted to this unique Antarctic lake environment.     

Nitrate reductase activity,biomass, yield,and quality in cotton in response to nitrogen fertilization

In the production of cotton (Gossypium hirsutum L.), nitrogen fertilization is one of the most costly crop practices, but important to reach high yields. However, high nitrogen (N) content in plants does not always translate into a high fibre production. One way of assessing the efficiency of the N fertilizer is through the enzymatic activity of the nitrate reductase (NR). This is a key enzyme in N assimilation, whose activity is regulated by a number of endogenous and exogenous factors that determine yield. The aim of this study was to assess the effect of N fertilization on yield, fibre quality, biomass, and NR enzymatic activity in vivo in the cotton variety Fiber Max 989. The evaluated application rates were 0, 50, 100, and 150 kg/ha of N, using urea as a source (46% N) in a randomizedblock design with three replicates. At harvest, the maximum yield of seed cotton and the greatest accumulation of total foliar biomass through time was reached after applying 150 kg N/ha. The different N-application rates did not affect the components of cotton-fibre quality. The activity of endogenous NR was greater on plants where 150 kg N/ha were applied. The highest cotton yield and N contents were obtained on these plants. Therefore, the NR activity in vivo could be used as a bioindicator of the N nutritional level in cotton.     

Technical advance: spatio-temporal analysis of mitotic activity with a labile cyclin-GUS fusion protein

Plant growth responds rapidly to developmental and environmental signals, but the underlying changes in cell division activity are poorly understood. A labile cyclin-GUS reporter was developed to facilitate the spatio-temporal analysis of cell division patterns. The chimeric reporter protein is turned over every cell cycle and hence its histochemical activity accurately reports individual mitotic cells. Using Arabidopsis plants transformed with cyclin-GUS, we visualized patterns of mitotic activity in wounded leaves which suggest a role for cell division in structural reinforcement.