Nitric oxide alleviates manganese toxicity by preventing oxidative stress in excised rice leaves

In the present study, we have investigated the effects of nitric oxide (NO) on alleviating manganese (Mn)-induced oxidative stress in rice leaves. Exogenous MnCl₂ treatment to excised rice leaves for 24 and 48 h resulted in increased production of H₂O₂ and lipid peroxides, decline in the levels of antioxidants, glutathione and ascorbic acid, and increased activities of antioxidative enzymes, superoxide dismutase, guaiacol peroxidase, catalase, ascorbate peroxidase, dehydroascorbate reductase, and glutathione reductase. Treatment of rice leaves with 100 μM sodium nitroprusside (SNP), a NO donor, was effective in reducing Mn-induced increased levels of H₂O₂, lipid peroxides and increased activities of antioxidative enzymes. The levels of reduced ascorbate and glutathione were considerably recovered due to SNP treatment. The effect of SNP was reversed by the addition of NO scavenger, 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (c-PTIO) suggesting that ameliorating effect of SNP is due to release of NO. The results indicate that MnCl₂ induces oxidative stress in excised rice leaves, lowers the levels of reduced ascorbate and glutathione, and elevates activities of the key antioxidative enzymes. NO appears to provide a protection to the rice leaves against Mn-induced oxidative stress and that exogenous NO application could be advantageous in combating the deleterious effects of Mn-toxicity in rice plants.     

Synthesis of silver nanoparticles by Bacillus clausii and computational profiling of nitrate reductase enzyme involved in production

Biogenic synthesis of silver nanoparticles using microorganisms has found interest recently since last decade because of their prospect to synthesize nanoparticles of various size, shape and morphology which are eco-friendly. Here, an eco-friendly method for production of silver nanoparticles from Bacillus clausii cultured from Enterogermina is explored. Along with the biosynthesis and conformity test, in silico studies was done on NADPH dependent nitrate reductase enzymes from the view point of designing a rational enzymatic strategy for the synthesis. The detailed characterization of the nanoparticles was carried out using UV-Vis spectroscopy, Dynamic Light Scattering (DLS) particle size analysis, Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) analysis. Computational profiling and in silico characterization of NADH dependent enzymes was carried out based on literature and work done so far. Nitrate reductase sequence was retrieved from NCBI for characterization. Secondary structure was evaluated and verified by JPred as well as SOPMA Tool. Tertiary structure was also modeled by MODELLER and ITASSER parallel and the best structure was selected based on energy values. Structure validation was done by GROMACS and RMSD, RMSF, temperature variation plot were also plotted. Interactions graphs between nitrate reductase and ligand silver nitrate was done through molecular docking using Hex.     

Relationship of Parental Genetic Distance with Heterosis and Specific Combining Ability in Sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.) Based on Phenotypic and Molecular Marker Analysis

The genetic distance analysis for selection of suitable parents has been established and effectively used in many crops; however, there is dearth of conclusive report of relationship of genetic distance analysis with heterosis in sesame. In the present study, an attempt was made to estimate the associations of genetic distances using SSR (GDSSR), seed-storage protein profiling (GDSDS) and agro-morphological traits (GDMOR) with hybrid performance. Seven parents were selected from 60 exotic and Indian genotypes based on genetic distance from clustering pattern based on SSR, seed-storage protein, morphological traits and per se performance. For combining ability analysis, 7 parents and 21 crosses generated from 7 × 7 half diallel evaluated at two environments in a replicated field trial during pre-kharif season of 2013. Compared with the average parents yield (12.57 g plant^?1), eight hybrids had a significant (P < 0.01) yield advantage across environments, with averages of 26.94 and 29.99% for better-parent heterosis (BPH) and mid-parent heterosis (MPH), respectively, across environments. Highly significant positive correlation was observed between specific combining ability (SCA) and per se performance (0.97), while positive non-significant correlation of BPH with GDSSR (0.048), and non-significant negative correlations with GDMOR (? 0.01) and GDSDS (? 0.256) were observed. The linear regressions of SCA on MPH, BPH and per se performance of F₁s were significant with R² value of 0.88, 0.84 and 0.95 respectively. The present findings revealed a weak association of GDSSR with F₁’s performance; however, SCA has appeared as an important factor in the determination of heterosis and per se performance of the hybrids. The present findings also indicated that parental divergence in the intermediate group would likely produce high heterotic crosses in sesame.     

Phenolic compounds in seedlings of Betula pubescens and B. pendula are affected by enhanced UVB radiation and different nitrogen regimens during early ontogeny

We studied the ability of tree seedlings to respond to two environmental factors, elevated ultraviolet B (UVB) radiation and availability of nitrogen (N), at the beginning of their development. Seeds of two birch species, Betula pubescens Ehrh. (common white birch) and B. pendula Roth (silver birch), were germinated and the seedlings grown in an experimental field in eastern Finland. The experimental design consisted of a constant 50% increase in UVB radiation (including a slight increase in UVA), a UVA control (a slight increase in UVA) and a control. The seedlings were fertilized with three levels of N. The experiment lasted for 2 months; aboveground biomass was measured and the most mature leaf of each seedling was taken for the analyses of phenolics. Growth of the seedlings was not significantly affected by enhanced UVB, but was increased by increasing N. Elevated UVB induced significant changes in phenolic compounds. Quercetin glycosides were accumulated in the leaves of both species in response to UVB; this is considered to be a protective response. However, the direction of the responses of individual phenolics to different N regimens differed. In addition, concentration of soluble condensed tannins was lower at moderate N than that at lower levels of N in both species; on the contrary, in B. pubescens the concentration of insoluble condensed tannins was highest at moderate N. No significant interaction between UV and N was detected, and the responses of the two species were highly similar to UVB, while the responses to N regimens varied slightly more between species.     

Development and Evaluation of Biodegradable Chitosan Films of Metronidazole and Levofloxacin for the Management of Periodontitis

Metronidazole (MZ) and levofloxacin (LF) are widely employed for treatment of periodontitis, but high oral dose and resistance development after long-term oral administration limit their use. The aim of this study was to alleviate shortcomings in the treatment of periodontitis by fabrication of intrapocket, biodegradable films of chitosan (CS) loaded with MZ and LF meant for inserting into periodontal pockets to treat infections. The films were developed by solvent casting technique using propylene glycol as plasticizer and glutaraldehyde as crosslinking agent. Their physical characteristics, such as drug content, surface pH, swelling index, and folding endurance, exhibited results within limit. Further, FTIR and DSC studies revealed stability of films and compatibility between drugs and excipients. SEM images of films showed the presence of free drug particles on the surface causing burst effect. In vitro release in McIlvaine buffer pH 6.6 was of sustained nature assisted by the burst effect. CS and crosslinking agent concentrations negatively affected drug release and positively affected T₉₀ (time for releasing 90% of the drug) due to altered matrix density. In contrast, the plasticizer concentration increases membrane permeability and hence increased drug release, lowering T₉₀. Crosslinked films demonstrated sustained release up to 7 days. The antibacterial efficacy of films was tested on Staphylococcus aureus and Escherichia coli, indicating good antibacterial activity. Clinical trials on patients proved the therapeutic efficacy of the films by a significant (p?<?0.05) decrease in the clinical markers of periodontitis, i.e. gingival index, plaque index and pocket depth. Conclusively, the films of MZ and LF were successful tools for the management of periodontitis.     

Heavy metal (Pb) accumulation in metallophytes as influenced by the variations in rhizospheric and non-rhizospheric soils physico-chemical characteristics

Activities at root-soil interface determine the solubility and uptake of metals by plants. Metal accumulation in plant species (Imperata cylindrical, Cynodon dactylon, Eleucine indica, Gomphrena celosoides, Sporobolus pyramidalis, Chromolaena odorata and Rhynchospora corymbosa) growing on Pb contaminated site as influenced by variations in physico-chemical characteristics, dissolved organic matter (DOM), Pb fractionation and different functional groups (using Fourier Transmittance Infra-red) of rhizospheric and non-rhizospheric soils was assessed. The electrical conductivity (2660–5520 µs) and Pb concentrations (51390.0–64080.0 mg/kg) were more in non-rhizospheric than rhizospheric soils having 276 µs to 3160 µs EC and 3289.0 to 44850.0 mg/kg Pb. More nutrients, DOM and carbohydrates functional groups (C-O; 1100 -1000 and O-H; 3700–3600) were found in rhizospheric compared to non-rhizospheric soils. The pH was slightly acidic (5.0–5.54) and E. indica with the lowest pH (5.0) accumulated highest Pb concentrations in shoot (8030 mg/kg) and root (16380 mg/kg) while C. odorata with highest values of pH, P, Ca and Mg in rhizospheric soil accumulated the least (root; 331.6 and shoot: 209.0 mg/kg). Pb was more in organic and residual fractions of rhizospheric and non-rhizospheric soils respectively. Reduction in pH, EC coupled with nutrients and DOM availability increased Pb uptake by plants.     

Isotherm and kinetic models and cell surface analysis for determination of the mechanism of metal sorption by Aspergillus versicolor

The isolate Aspergillus versicolor was obtained from an estuary, which is exposed to metal contamination. It was found to have a good metal tolerance and sorption capacity. Further studies revealed that the rate of metal removal from solution is very rapid in the first 5-10 min, and is favoured by a pH of 6.0. The biosorption data obtained was explained by the Freundlich adsorption isotherm model and followed a pseudo-second order kinetics reaction. The fungus showed a higher accumulation of fatty acids when grown in presence of metals as compared to the mycelium grown in absence of the metal; there was also an increase in the saturation index of fatty acids in presence of Cu(2+) which serves as a protective mechanism for the fungus. Fourier Transform Infrared, scanning electron microscopy and EDAX analysis indicated that metal removal from solution by A. versicolor occurred by a passive adsorption to the fungal cell surface, involving an ion exchange mechanism.     

Regulation of cell adhesion by protein-tyrosine phosphatases. I. Cell-matrix adhesion

Protein-tyrosine phosphatases are key regulators of protein tyrosine phosphorylation. More than merely terminating the pathways initiated by protein-tyrosine kinases, phosphatases are active participants in many signaling pathways. Signals involving tyrosine phosphorylation are frequently generated in response to cell-matrix adhesion. In addition, high levels of protein tyrosine phosphorylation generally promote disassembly or turnover of adhesions. In this brief review, we will discuss the role of protein-tyrosine phosphatases in cell-matrix adhesions.