The cytoplasmic membrane as the site of the antimicrobial action of N-octylethanolamine

On agar spread plates, N-octylethanolamine was biocidal at comparable minimum inhibitory concentration (MIC) values (3–4mm) against Pseudomonas aeruginosa (two strains), Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida tropicalis, and Acremonium sp. which had been grown on a number of different media. The inhibition was greater at higher pH values. In liquid culture, growth inhibition by 3mm N-octylethanolamine was accompanied by cell lysis. Both effects could be prevented by the presence of 1mm spermine or spermidine, but only in bacteria, and not at high pH values. These effects of the polyamines were shown to be non-specific, being shared by other polycations and Mg²⁺ ions. N-Octylethanolamine at concentrations above its MIC caused total inhibition of the oxidation of 1mm glucose by Ps. aeruginosa (CAS1 and PAO1), E. coli, or C. tropic an effect that was partially reversible by Mg²⁺ ions. At concentrations below the MIC, there was little inhibit ion of glucose oxidation but a potent inhibition of the extrusion of ethidium bromide from intact cells of E. coli, suggesting that at such concentrations N-octylethanolamine is uncoupling oxidative phosphorylation. The data presented confirm the view that the biocidal effects are due to action on the cytoplasmic membrane.     

Multiple colonizations of a remote oceanic archipelago by one species: how common is long‐distance dispersal?

Aim  It is well established that many groups of plants and animals have undergone long-distance dispersal, but the extent to which this continues beyond initial colonization is largely unknown. To provide further insight into the frequency of gene flow mediated by long-distance dispersal, we investigated the origins of the fern Asplenium hookerianum on the Chatham Islands, and present a review of the contribution of molecular data to elucidating the origins of this archipelago's biota.
Location  Chatham Islands and New Zealand. A. hookerianum is scarce on the Chatham Islands but common in New Zealand, some 800 km to the west.
Methods  We compared chloroplast trnL–trnF DNA sequence data from Chatham Islands' A. hookerianum with extensive phylogeographic data for this genetically variable species in mainland New Zealand.
Results  Our sequencing revealed the presence of two haplotypes in Chatham Islands' A. hookerianum . These haplotypes differed by four mutational events and were each more closely related to haplotypes found in New Zealand than to each other.
Main conclusions  Despite the rarity of A. hookerianum on the Chatham Islands, its populations there appear to derive from at least two long-distance dispersal events from New Zealand, these possibly originating from different areas. We suggest that long-distance transoceanic dispersal, and the gene flow it can mediate, may be more common than is generally appreciated.     

Mapping Soil Properties of Africa at 250 m Resolution: Random Forests Significantly Improve Current Predictions

80% of arable land in Africa has low soil fertility and suffers from physical soil problems. Additionally, significant amounts of nutrients are lost every year due to unsustainable soil management practices. This is partially the result of insufficient use of soil management knowledge. To help bridge the soil information gap in Africa, the Africa Soil Information Service (AfSIS) project was established in 2008. Over the period 2008–2014, the AfSIS project compiled two point data sets: the Africa Soil Profiles (legacy) database and the AfSIS Sentinel Site database. These data sets contain over 28 thousand sampling locations and represent the most comprehensive soil sample data sets of the African continent to date. Utilizing these point data sets in combination with a large number of covariates, we have generated a series of spatial predictions of soil properties relevant to the agricultural management—organic carbon, pH, sand, silt and clay fractions, bulk density, cation-exchange capacity, total nitrogen, exchangeable acidity, Al content and exchangeable bases (Ca, K, Mg, Na). We specifically investigate differences between two predictive approaches: random forests and linear regression. Results of 5-fold cross-validation demonstrate that the random forests algorithm consistently outperforms the linear regression algorithm, with average decreases of 15–75% in Root Mean Squared Error (RMSE) across soil properties and depths. Fitting and running random forests models takes an order of magnitude more time and the modelling success is sensitive to artifacts in the input data, but as long as quality-controlled point data are provided, an increase in soil mapping accuracy can be expected. Results also indicate that globally predicted soil classes (USDA Soil Taxonomy, especially Alfisols and Mollisols) help improve continental scale soil property mapping, and are among the most important predictors. This indicates a promising potential for transferring pedological knowledge from data rich countries to countries with limited soil data.     

Monolayer formation of human osteoblastic cells on vertically aligned multiwalled carbon nanotube scaffolds

Monolayer formation of SaOS‐2 (human osteoblast‐like cells) was observed on VACNT (vertically aligned multiwalled carbon nanotubes) scaffolds without purification or functionalization. The VACNT were produced by a microwave plasma chemical vapour deposition on titanium surfaces with nickel or iron as catalyst. Cell viability and morphology studies were evaluated by LDH (lactate dehydrogenase) release assay and SEM (scanning electron microscopy), respectively. The non‐toxicity and the flat spreading with monolayer formation of the SaOs‐2 on VACNT scaffolds surface indicate that they can be used for biomedical applications.     

Evidence for a role for the p110-α isoform of PI3K in skeletal function

Signaling through phosphatidylinositol-3 kinases (PI3K) regulates fundamental cellular processes such as survival and growth, and these lipid kinases are currently being investigated as therapeutic targets in several contexts. In skeletal tissue, experiments using pan-specific PI3K inhibitors have suggested that PI3K signaling influences both osteoclast and osteoblast function, but the contributions of specific PI3K isoforms to these effects have not been examined. In the current work, we assessed the effects of pharmacological inhibitors of the class Ia PI3Ks, α, β, and δ, on bone cell growth, differentiation and function in vitro. Each of the class Ia PI3K isoforms is expressed and functionally active in bone cells. No consistent effects of inhibitors of p110-β or p110-δ on bone cells were observed. Inhibitors of p110-α decreased osteoclastogenesis by 60-80% (p < 0.001 vs control) by direct actions on osteoclast precursors, and decreased the resorptive activity of mature osteoclasts by 60% (p < 0.01 vs control). The p110-α inhibitors also decreased the growth of osteoblastic and stromal cells (p < 0.001 vs control), and decreased differentiated osteoblast function by 30% (p < 0.05 vs control). These data suggest that signaling through the p110-α isoform of class Ia PI3Ks positively regulates the development and function of both osteoblasts and osteoclasts. Therapeutic agents that target this enzyme have the potential to significantly affect bone homeostasis, and evaluation of skeletal endpoints in clinical trials of such agents is warranted.     

Impacts of T-Phylloplanin gene knockdown and of Helianthus and Datura phylloplanins on Peronospora tabacina spore germination and disease potential

T-phylloplanin proteins secreted to aerial surfaces of tobacco (Nicotiana tabacum) by short procumbent trichomes inhibit spore germination and blue mold disease caused by the oomycete pathogen Peronospora tabacina. Many other plants were found to contain water-washed leaf surface proteins (phylloplanins), but the functions and properties of these are not known. Here we extend earlier evidence for the antifungal activity of T-phylloplanins using a reverse genetics approach. RNA interference of the T-phylloplanin gene in tobacco 'T.I. 1068' resulted in loss of T-phylloplanin mRNA and protein, loss of in vitro spore germination inhibition activity, and leaf infection inhibition activity of leaf water washes from RNA interference plants, and young knockdown plants were susceptible to disease. The glycoprotein character, adaxial-leaf-surface enrichment of, and renewability of T-phylloplanins are also described. We also report that leaf water washes of sunflower (Helianthus annuus) and jimson weed (Datura metel), but not soybean (Glycine max), like that of tobacco, possess ProteinaseK- and boiling-sensitive P. tabacina spore germination and tobacco leaf infection inhibition activities. Results establish that T-phylloplaninins of tobacco are active in P. tabacina inhibition, and indicate that leaf surface proteins of certain non-Nicotiana species that are not susceptible to P. tabacina disease can inhibit germination of spores of this oomycete pathogen and inhibit tobacco leaf infection by this pathogen.     

Alloimmunity to human endothelial cells derived from cord blood progenitors

There is considerable interest in exploiting circulating endothelial progenitor cells (EPCs) for therapeutic organ repair. Such cells may be differentiated into endothelial cells (ECs) in vitro and then expanded for use in tissue engineering. Vessel-derived ECs are variably immunogenic, depending upon tissue source, and it is unknown whether ECs derived from cord blood EPCs are able to initiate an allogeneic response. In this study, we compare the phenotype and alloantigenicity of human cord blood progenitor cell-derived ECs with HUVECs isolated from the same donors. Human cord blood progenitor cell-derived ECs are very similar to HUVECs in the expression of proteins relevant for alloimmunity, including MHC molecules, costimulators, adhesion molecules, cytokines, chemokines, and IDO, and in their ability to initiate allogeneic CD4(+) and CD8(+) memory T cell responses in vitro and in vivo. These findings have significant implications for the use of cord blood EPCs in regenerative medicine or tissue engineering.     

Dendritic cell function can be modulated through cooperative actions of TLR ligands and invariant NKT cells

The quality of signals received by dendritic cells (DC) in response to pathogens influences the nature of the adaptive response. We show that pathogen-derived signals to DC mediated via TLRs can be modulated by activated invariant NKT (iNKT) cells. DC maturation induced in vivo with any one of a variety of TLR ligands was greatly improved through simultaneous administration of the iNKT cell ligand alpha-galactosylceramide. DC isolated from animals treated simultaneously with TLR and iNKT cell ligands were potent stimulators of naive T cells in vitro compared with DC from animals treated with the ligands individually. Injection of protein Ags with both stimuli resulted in significantly improved T cell and Ab responses to coadministered protein Ags over TLR stimulation alone. Ag-specific CD8(+) T cell responses induced in the presence of the TLR4 ligand monophosphoryl lipid A and alpha-galactosylceramide showed faster proliferation kinetics, and increased effector function, than those induced with either ligand alone. Human DC exposed to TLR ligands and activated iNKT cells in vitro had enhanced expression of maturation markers, suggesting that a cooperative action of TLR ligands and iNKT cells on DC function is a generalizable phenomenon across species. These studies highlight the potential for manipulating the interactions between TLR ligands and iNKT cell activation in the design of effective vaccine adjuvants.     

A conditionally immortalized cell line model for the study of human prostatic epithelial cell differentiation

In the normal human prostate, undifferentiated proliferative cells reside in the basal layer and give rise to luminal secretory cells. There are, however, few epithelial cell lines that have a basal cell phenotype and are able to differentiate. We set out to develop a cell line with these characteristics that would be suitable for the study of the early stages of prostate epithelial cell differentiation. We produced a matched pair of conditionally immortalized prostate epithelial and stromal cell lines derived from the same patient. The growth of these cells is temperature dependent and differentiation can be induced following a rise in culture temperature. Three-dimensional co-cultures of these cell lines elicited gland-like structures reminiscent of prostatic acini. cDNA microarray analysis of the epithelial line demonstrated changes in gene expression consistent with epithelial differentiation. These genes may prove useful as markers for different prostate cell types. The cell lines provide a model system with which to study the process of prostatic epithelial differentiation and stromal-epithelial interactions. This may prove to be useful in the development of differentiation-targeted prostate cancer therapies.