Solvent polarity effects on supramolecular chirality of a polyfluorene‐thiophene copolymer

This study demonstrates the supramolecular chirality control of a conjugated polymer via solvent polarity. We designed and synthesized a chiral polyfluorene‐thiophene copolymer having two different chiral side chains at the 9‐position of the fluorene unit. Chiral cyclic and alkyl ethers with different polarities were selected as the chiral side chains. The sign of the circular dichroism spectra in the visible wavelength region was affected by the solvent system, resulting from the change of supramolecular structure. The estimation of the solubility parameter revealed that the solubility difference of the side chains contributed to the change of the circular dichroism sign, which was also observed in spin‐coated films prepared from good solvents having different polarities.     

Involvement of ethylene signaling in Azospirillum sp. B510-induced disease resistance in rice

A bacterial endophyte Azospirillum sp. B510 induces systemic disease resistance in the host without accompanying defense-related gene expression. To elucidate molecular mechanism of this induced systemic resistance (ISR), involvement of ethylene (ET) was examined using OsEIN2-knockdown mutant rice. Rice blast inoculation assay and gene expression analysis indicated that ET signaling is required for endophyte-mediated ISR in rice.

Abbreviations: ACC: 1-aminocyclopropane-1-carboxylic acid; EIN2: ethylene-insensitive protein 2; ET: ethylene; ISR: induced systemic resistance; JA: jasmonic acid; RNAi: RNA interference; SA: salicylic acid; SAR: systemic acquired resistance     

Design,synthesis, and biological evaluation of novel ubiquitin-activating enzyme inhibitors

Ubiquitin-activating enzyme (E1), which catalyzes the activation of ubiquitin in the initial step of the ubiquitination cascade, is a potential therapeutic target in multiple myeloma and breast cancer treatment. However, only a few E1 inhibitors have been reported to date. Moreover, there has been little medicinal chemistry research on the three-dimensional structure of E1. Therefore, in the present study, we attempted to identify novel E1 inhibitors using structure-based drug design. Following the rational design, synthesis, and in vitro biological evaluation of several such compounds, we identified a reversible E1 inhibitor (4b). Compound 4b increased p53 levels in MCF-7 breast cancer cells and inhibited their growth. These findings suggest that reversible E1 inhibitors are potential anticancer agents.     

Separation of glycosphingolipids with titanium dioxide

We introduce the principle of a new technique to isolate glycosphingolipids (GSLs) from phospholipids. Neutral and acidic GSLs in organic solvent bind to titanium dioxide under neutral pH and can be eluted with 5 mg/ml of 2,5-dihydroxybenzoic acid in methanol. This special property is applicable for eliminating phospholipids, including sphingomyelin, which cannot be eliminated by a typical mild alkaline treatment. By using this technique, we demonstrated the rapid separation of minor components of GSLs, namely sulfatide and gangliosides from rabbit serum and liver, respectively. The minor GSL components were effectively purified despite both sources containing tremendous amount of phospholipids and simple lipids such as cholesterol, cholesteryl esters and triglycerides.     

Using food network unfolding to evaluate food–web complexity in terms of biodiversity: theory and applications

Food–web complexity often hinders disentangling functionally relevant aspects of food–web structure and its relationships to biodiversity. Here, we present a theoretical framework to evaluate food–web complexity in terms of biodiversity. Food network unfolding is a theoretical method to transform a complex food web into a linear food chain based on ecosystem processes. Based on this method, we can define three biodiversity indices, horizontal diversity (D_H), vertical diversity (D_V) and range diversity (D_R), which are associated with the species diversity within each trophic level, diversity of trophic levels, and diversity in resource use, respectively. These indices are related to Shannon's diversity index (H′), where H′ = D_H + D_V ? D_R. Application of the framework to three riverine macroinvertebrate communities revealed that D indices, calculated from biomass and stable isotope features, captured well the anthropogenic, seasonal, or other within‐site changes in food–web structures that could not be captured with H′ alone.     

ICAMs Are Not Obligatory for Functional Immune Synapses between Naive CD4 T Cells and Lymph Node DCs

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Nitric oxide-induced salt stress tolerance in plants: ROS metabolism,signaling, and molecular interactions

Nitric oxide (NO), a non-charged, small, gaseous free-radical, is a signaling molecule in all plant cells. Several studies have proposed multifarious physiological roles for NO, from seed germination to plant maturation and senescence. Nitric oxide is thought to act as an antioxidant, quenching ROS during oxidative stress and reducing lipid peroxidation. NO also mediates photosynthesis and stomatal conductance and regulates programmed cell death, thus providing tolerance to abiotic stress. In mitochondria, NO participates in the electron transport pathway. Nitric oxide synthase and nitrate reductase are the key enzymes involved in NO-biosynthesis in aerobic plants, but non-enzymatic pathways have been reported as well. Nitric oxide can interact with a broad range of molecules, leading to the modification of protein activity, GSH biosynthesis, S-nitrosylation, peroxynitrite formation, proline accumulation, etc., to sustain stress tolerance. In addition to these interactions, NO interacts with fatty acids to form nitro-fatty acids as signals for antioxidant defense. Polyamines and NO interact positively to increase polyamine content and activity. A large number of genes are reprogrammed by NO; among these genes, proline metabolism genes are upregulated. Exogenous NO application is also shown to be involved in salinity tolerance and/or resistance via growth promotion, reversing oxidative damage and maintaining ion homeostasis. This review highlights NO-mediated salinity-stress tolerance in plants, including NO biosynthesis, regulation, and signaling. Nitric oxide-mediated ROS metabolism, antioxidant defense, and gene expression and the interactions of NO with other bioactive molecules are also discussed. We conclude the review with a discussion of unsolved issues and suggestions for future research.     

Effect of biodegradable chelating ligands on Fe uptake in and growth of marine microalgae

Iron (Fe) is an important nutrient for phytoplankton. The low solubility of Fe in oxic waters can be a growth-limiting factor for phytoplankton. Synthetic aminopolycarboxylates (APCs) such as ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) are widely used as Fe complexing agents for microalgae culture. However, the presence of these non-ready biodegradable APC_S in aquatic systems may have serious environmental consequences. In the present study, the effects of biodegradable chelating ligands (hydroxyiminodisuccinic acid (HIDS), methylglycinediacetic acid (MGDA), and iminodisuccinate (IDS)) on Fe uptake in and growth of three coastal microalgae (Heterosigma akashiwo, Prymnesium parvum, and Skeletonema marinoi-dohrnii complex) were investigated, and the results were compared with those of non-ready biodegradable APCs (EDTA, ethylenediamine tetra-methylene phosphonic acid (EDTMP), and DTPA). The biodegradable chelating ligands did not have significant growth inhibition effect on the phytoplankton. Although the growth of the algae (except S. marinoi-dohrnii complex) was not affected substantially by 1.5 and 7.5 μM of DTPA, growth inhibition occurred by 7.5 μM of EDTMP and 150 μM of EDTA, DTPA, and EDTMP. The effect of chelating ligands on microalgal growth was likely to be associated with the intracellular Fe uptake influenced by the chelating ligands. On average, intracellular Fe concentrations for biodegradable chelating ligands were substantially higher than those for non-ready biodegradable APCs. Except H. akashiwo, the ratio of intra/extracellular Fe concentrations was highest for MGDA followed by IDS and HIDS. The results indicate that biodegradable chelating ligands are more efficient than non-ready biodegradable APCs in intracellular Fe uptake and algal growth.     

Evaluation of Francisella tularensis ΔpdpC as a candidate live attenuated vaccine against respiratory challenge by a virulent SCHU P9 strain of Francisella tularensis in a C57BL/6J mouse model

Francisella tularensis, which causes tularemia, is an intracellular gram‐negative bacterium. F. tularensis has received significant attention in recent decades because of its history as a biological weapon. Thus, development of novel vaccines against tularemia has been an important goal. The attenuated F. tularensis strain ΔpdpC, in which the pathogenicity determinant protein C gene (pdpC) has been disrupted by TargeTron mutagenesis, was investigated as a potential vaccine candidate for tularemia in the present study. C57BL/6J mice immunized s.c. with 1 × 10⁶ CFUs of ΔpdpC were challenged intranasally with 100× the median lethal dose (LD₅₀) of a virulent SCHU P9 strain 21 days post immunization. Protection against this challenge was achieved in 38% of immunized C57BL/6J mice administered 100 LD₅₀ of this strain. Conversely, all unimmunized mice succumbed to death 6 days post challenge. Survival rates were significantly higher in vaccinated than in unimmunized mice. In addition, ΔpdpC was passaged serially in mice to confirm its stable attenuation. Low bacterial loads persisted in mouse spleens during the first to tenth passages. No statistically significant changes in the number of CFUs were observed during in vivo passage of ΔpdpC. The inserted intron sequences for disrupting pdpC were completely maintained even after the tenth passage in mice. Considering the stable attenuation and intron sequences, it is suggested that ΔpdpC is a promising tularemia vaccine candidate.