Syntheses, structures and magnetic properties of μ1,5 dicyanamide bridged coordination polymers of copper(II) and nickel(II) containing a tetradentate N-donor Schiff base

One neutral [Cu₂(enbzpy)(dca)₄]_n (1) and one polycationic [Ni(enbzpy)(dca)]_n(ClO₄)_n (2) [enbzpy = N,N′-(bis-(pyridin-2-yl)benzylidene)ethane-1,2-diamine; dca = dicyanamide] 1D coordination polymers are synthesized and characterized. X-ray structural analyses reveal each copper(II) center in 1 to adopt a distorted square pyramidal geometry with a CuN₅ chromophore coordinated through two N atoms of the Schiff base behaving as a binucleting bis(bidentate) ligand and three nitrile N atoms of one terminal and two single μ_1,5 dca units leading to a 1D ladder structure. In 2, each nickel(II) center has a distorted octahedral coordination environment with an NiN₆ chromophore bound by four N atoms of enbzpy through tetradentate chelation and two nitrile N atoms of two different single bridged μ_1,5 dca units; the latter connects other neighboring metal centers in a non-ending fashion affording a 1D chain. Variable-temperature magnetic susceptibility measurements of 1 and 2 show weak antiferromagnetic interactions among the metal centers through μ_1,5 dca bridges.     

Distinct structural and functional roles of conserved residues in the first extracellular domain of receptors for corticotropin-releasing factor and related G-protein-coupled receptors

The G-protein-coupled receptor B1 family includes corticotropin-releasing factor (CRF), growth hormone-releasing hormone, incretin, and pituitary adenylate cyclase-activating polypeptide receptors. The three-dimensional NMR structure of the first extracellular domain (ECD1) of CRF receptor 2beta (CRF-R2beta), free and complexed with astressin, comprises a Sushi domain. This domain is stabilized in part by a salt bridge between Asp(65) and Arg(101). Analogous residues are conserved in other members of the B1 family. To address the importance of the salt bridge residues within this receptor family, we studied the effects of mutating the residues in full-length CRF-R2beta and isolated ECD1. Mutation D65A or D65R/R101D resulted in loss of the canonical disulfide arrangement, whereas R101A retained the Cys(4)-Cys(6) disulfide bond. The mutations resulted in misfolding within the ECD1 as determined by NMR and 1-anilino-8-naphthalenesulfonate binding but did not prevent cell surface expression. The D65A mutation in CRF-R2beta greatly reduced binding and activation, but the R101A substitution had only a small effect. Similar effects were seen on astressin binding to the ECD1. The different interactions of Asp(65) and Arg(101), deduced from the three-dimensional structure of the complex, are consistent with the differential effects seen in the mutants. The reduction in binding of Asp(65) mutants is a consequence of a distinct Asp(65)-Trp(71) interaction, which stabilizes the ligand-binding loop. Hence, loss of the salt bridge leads to disruption of the overall fold but does not abolish function. Because homologous mutations in other B1 receptors produce similar effects, these conserved residues may play similar roles in the entire receptor family.     

Microencapsulation of Zanthoxylum limonella oil (ZLO) in glutaraldehyde crosslinked gelatin for mosquito repellent application

Glutaraldehyde (GA) crosslinked gelatin (G) microcapsules containing Zanthoxylum limonella oil (ZLO) were prepared by coacervation technique. The effect of various parameters such as variation of oil-loading, gelatin concentration and degree of crosslinking on release rate of oil were studied. Scanning electron microscopy (SEM) was used to understand the surface characteristics of microcapsules. FTIR-results indicated the absence of any significant interaction between polymer and oil.     

Biosorption of cesium-137 and strontium-90 by mucilaginous seeds of Ocimum basilicum

Mucilaginous seeds of Ocimum basilicum were used in uptake studies with cesium-137 and strontium-90. Results showed that uptake was dependent on the structural integrity of the mucilage fibrils. Water imbibed seeds showed higher adsorption of both 137Cs and 90Sr in comparison to seeds pretreated with NaOH, HCl and Na-periodate solution. The uptake was pH dependent and while some divalent metal ions had no or little detrimental effect, the alkali metal ions Li+, Na+ and K+ decreased the uptake. The maximum adsorption capacity was 160 mg cesium g(-1) and 247 mg strontium g(-1) seed dry weight.     

ACC deaminase-containing Arthrobacter protophormiae induces NaCl stress tolerance through reduced ACC oxidase activity and ethylene production resulting in improved nodulation and mycorrhization in Pisum sativum

Induction of stress ethylene production in the plant system is one of the consequences of salt stress which apart from being toxic to the plant also inhibits mycorrhizal colonization and rhizobial nodulation by oxidative damage. Tolerance to salinity in pea plants was assessed by reducing stress ethylene levels through ACC deaminase-containing rhizobacteria Arthrobacter protophormiae (SA3) and promoting plant growth through improved colonization of beneficial microbes like Rhizobium leguminosarum (R) and Glomus mosseae (G). The experiment comprised of treatments with combinations of SA3, G, and R under varying levels of salinity. The drop in plant biomass associated with salinity stress was significantly lesser in SA3 treated plants compared to non-treated plants. The triple interaction of SA3 + G + R performed synergistically to induce protective mechanism against salt stress and showed a new perspective of plant-microorganism interaction. This tripartite collaboration increased plant weight by 53%, reduced proline content, lipid peroxidation and increased pigment content under 200 mM salt condition. We detected that decreased ACC oxidase (ACO) activity induced by SA3 and reduced ACC synthase (ACS) activity in AMF (an observation not reported earlier as per our knowledge) inoculated plants simultaneously reduced the ACC content by 60% (responsible for generation of stress ethylene) in SA3 + G + R treated plants as compared to uninoculated control plants under 200 mM salt treatment. The results indicated that ACC deaminase-containing SA3 brought a putative protection mechanism (decrease in ACC content) under salt stress, apart from alleviating ethylene-induced damage, by enhancing nodulation and AMF colonization in the plants resulting in improved nutrient uptake and plant growth.     

A natural plant growth promoter,calliterpenone, enhances growth and biomass,carbohydrate, and lipid production in cyanobacterium Synechocystis PCC 6803

Cyanobacteria have evolved photosynthetic mechanisms in which solar energy is used to fix CO₂ into carbohydrates. The lipids from cyanobacteria can be converted to biodiesel by extraction–transesterification methods. The present study demonstrates the usefulness of the natural plant and microbial growth promoter calliterpenone from the plant Callicarpa macrophylla supplemented at three different doses (15, 25, 50 μL of a 0.01 mM solution) per 100 mL BG11⁺ medium for enhancing total biomass, carbohydrate, and lipid yields and reducing the surface-to-volume ratios of cells of Synechocystis PCC 6803. The enhanced total dried biomass, carbohydrate, and lipid production was 316.1, 140.34, and 130.76 %, respectively, higher than the control, and were obtained after 15 days of cultivation at the dose of 15 μL (0.01 mM) of calliterpenone per 100 mL BG11⁺ medium. A decrease in surface-to-volume ratio of cells from 1.19 to 0.84 compared to the control was also observed. Response surface methodology was used to optimize the doses of calliterpenone at different pH of growth media. An increase of 346.95, 187.2, and 134.46 % in biomass, carbohydrate, and lipid yields, respectively, was achieved after 10 days of cultivation in optimized BG11⁺ media at pH 7.5 and with 20 μL (0.01 mM) calliterpenone per 100 mL. Thus, this biomolecule can be exploited for higher yields of Synechocystis PCC 6803 in a relatively shorter culture time making this an attractive strategy for fuel production using this cyanobacterium.     

Binding of gemini bisbenzimidazole drugs with human telomeric G-quadruplex dimers: effect of the spacer in the design of potent telomerase inhibitors

The study of anticancer agents that act via stabilization of telomeric G-quadruplex DNA (G4DNA) is important because such agents often inhibit telomerase activity. Several types of G4DNA binding ligands are known. In these studies, the target structures often involve a single G4 DNA unit formed by short DNA telomeric sequences. However, the 3'-terminal single-stranded human telomeric DNA can form higher-order structures by clustering consecutive quadruplex units (dimers or n-mers). Herein, we present new synthetic gemini (twin) bisbenzimidazole ligands, in which the oligo-oxyethylene spacers join the two bisbenzimidazole units for the recognition of both monomeric and dimeric G4DNA, derived from d(T2AG3)4 and d(T2AG3)8 human telomeric DNA, respectively. The spacer between the two bisbenzimidazoles in the geminis plays a critical role in the G4DNA stability. We report here (i) synthesis of new effective gemini anticancer agents that are selectively more toxic towards the cancer cells than the corresponding normal cells; (ii) formation and characterization of G4DNA dimers in solution as well as computational construction of the dimeric G4DNA structures. The gemini ligands direct the folding of the single-stranded DNA into an unusually stable parallel-stranded G4DNA when it was formed in presence of the ligands in KCl solution and the gemini ligands show spacer length dependent potent telomerase inhibition properties.     

Don't forget to look down – collaborative approaches to predator conservation

Finding effective ways of conserving large carnivores is widely recognised as a priority in conservation. However, there is disagreement about the most effective way to do this, with some favouring top‐down ‘command and control’ approaches and others favouring collaboration. Arguments for coercive top‐down approaches have been presented elsewhere; here we present arguments for collaboration. In many parts of the developed world, flexibility of approach is built into the legislation, so that conservation objectives are balanced with other legitimate goals. In the developing world, limited resources, poverty and weak governance mean that collaborative approaches are likely to play a particularly important part in carnivore conservation. In general, coercive policies may lead to the deterioration of political legitimacy and potentially to non‐compliance issues such as illegal killing, whereas collaborative approaches may lead to psychological ownership, enhanced trust, learning, and better social outcomes. Sustainable hunting/trapping plays a crucial part in the conservation and management of many large carnivores. There are many different models for how to conserve carnivores effectively across the world, research is now required to reduce uncertainty and examine the effectiveness of these approaches in different contexts.     

Home ranges, movements, and activity of wolves (Canis lupus) in the Dalmatian part of Dinarids, Croatia

Home-range sizes, movements, and daily activity of wolves (Canis lupus L. 1758) were studied in Dalmatia, Croatia in 1998–2001. The total home ranges (100% MCP) of two packs were 160 km² and 141 km², mean=150.5 km². Core areas (50% kernel) were 26.2 km² and 3.3 km², respectively. Differences in core area sizes were influenced by human activity—hunting and sheep grazing. Compared with random locations, wolf locations were closer to the nearest water source (mean=937 m) and farther from houses (mean=653 m). Wolves were significantly more active during the night than during the day (activity indexes were 0.53 vs. 0.35), and night activity was higher during summer (0.58), and lower during winter (0.48). A correlation was found between distances traveled and activity index (r=0.58, p=0.003). Home range, seasonal variations in home-range size, habitat use, and activity of wolves in Dalmatia were oriented to make the compromise from danger of proximity to humans and also to benefit from human-related food sources.     

Uranyl tris nitrato as a luminescent probe for trace water detection in acetonitrile

Uranyl tris nitrato i.e. [UO₂(NO₃)₃]^– was formed by adding tetramethylammonium nitrate to uranyl nitrate in acetonitrile medium. The luminescence features of this complex in acetonitrile are very sensitive to water content, which could lead to the use of it as a luminescent probe for water present in acetonitrile. The luminescence intensity ratio of 507 to 467 nm peak of uranyl tris nitrato showed a linear response in the range 0–5% (v/v) water content in acetonitrile. The present method was applied for three synthetic samples of acetonitrile for water detection and the results obtained were compared using Karl Fischer titration. There was a good agreement in the values obtained by both the methods.