Pseudomonas Lipopeptide-Mediated Biocontrol: Chemotaxonomy and Biological Activity

Pseudomonas lipopeptides (Ps-LPs) play crucial roles in bacterial physiology, host–microbe interactions and plant disease control. Beneficial LP producers have mainly been isolated from the rhizosphere, phyllosphere and from bulk soils. Despite their wide geographic distribution and host range, emerging evidence suggests that LP-producing pseudomonads and their corresponding molecules display tight specificity and follow a phylogenetic distribution. About a decade ago, biocontrol LPs were mainly reported from the P. fluorescens group, but this has drastically advanced due to increased LP diversity research. On the one hand, the presence of a close-knit relationship between Pseudomonas taxonomy and the molecule produced may provide a startup toolbox for the delineation of unknown LPs into existing (or novel) LP groups. Furthermore, a taxonomy–molecule match may facilitate decisions regarding antimicrobial activity profiling and subsequent agricultural relevance of such LPs. In this review, we highlight and discuss the production of beneficial Ps-LPs by strains situated within unique taxonomic groups and the lineage-specificity and coevolution of this relationship. We also chronicle the antimicrobial activity demonstrated by these biomolecules in limited plant systems compared with multiple in vitro assays. Our review further stresses the need to systematically elucidate the roles of diverse Ps-LP groups in direct plant–pathogen interactions and in the enhancement of plant innate immunity.     

The therapeutic effect of low-level laser on repair of osteochondral defects in rabbit knee

INTRODUCTION: Low level laser therapy (LLLT) has been shown to enhance collagen production and wound healing but its effect on cartilage repair from biomechanical point of view is not known yet. The aim of present study was to evaluate the biomechanical behaviour of repairing osteochondral defect in rabbits which received a pulsed low-level gallium-arsenide (Ga-As) laser irradiation. MATERIALS AND METHODS: Osteochondral defects with 5mm diameter and 4mm in depth induced by drilling in right femoral patellar grooves of 41 adolescent male rabbits. They were divided into experimental and control groups. Experimental group received pulsed Ga-As (890nm) laser irradiation with energy density of 4.8J/cm(2). The rabbits in control group received placebo LLLT with shut-down equipment. The control defects were allowed to heal spontaneously. Each group were divided into three subgroups: A, B and C. Subgroups A, B and C were sacrificed on 4, 8, and 16 weeks after surgery. The knee joint were removed, and the defects were examined biomechanically by in situ-indentation method. The thickness, instantaneous and equilibrium indentation stiffness was measured during the test. Data were analysed using ANOVA and independent sample t-test. RESULT: While no difference was observed in the repaired cartilage biomechanical properties among 4th, 8th, 16th weeks in study groups. The equilibrium indentation stiffness of experimental group was significantly higher in 8th week in comparison with control group. CONCLUSION: LLLT significantly enhances the stiffness of repairing tissue in the 8th week post injury in osteochondral defects in rabbits.     

The use of starch‐modified magnetic Fe0 nanoparticles for naphthalene adsorption from water samples: Adsorption isotherm,kinetic and thermodynamic studies

This study was aimed at investigating the effectiveness of starch‐modified magnetic nanoparticles for the removal of naphthalene, which is a polycyclic aromatic hydrocarbon present in the majority of water sediments, from water resources. Magnetic Fe⁰ nanoparticles have recently been considered because of their high efficiency for contaminant removal. In the present study, Fe⁰ nanoparticles were synthesized using sulfate method and starch was used as a stabilizer. The size of the Fe⁰ nanoparticles was measured as approximately 45 nm using X‐ray diffraction and scanning electron microscopy analyses. The removal efficiency of naphthalene from water using the nanoparticles was evaluated based on various factors including the viscosity of naphthalene dissolved in water, and operation factors such as nanoparticle dosage, contact time, initial naphthalene concentration and pH in non‐continuous reactors were optimized. The results revealed that the starch‐modified nanoparticles have high efficiency for removal of dissolved naphthalene from aqueous solution. Under the optimum conditions, more than 99% of naphthalene at a pH of 5.0 with nanoparticle dosage of 0.05 g was removed from aqueous solution in 5 min. The equilibrium adsorption data were interpreted in terms of Langmuir, Freundlich and Temkin isotherm models and the goodness of fit was inspected using linear regression analysis. Our results indicated that the Langmuir model with maximum adsorption capacity was best fitted, suggesting monolayer adsorption. Moreover, it was found that the adsorption process followed the pseudo‐second‐order kinetic model. In addition, a thermodynamic study indicated that the adsorption process of naphthalene from aqueous solution by the starch‐modified nanoparticles was spontaneous and exothermic.     

Chromatographic Behavior of Food Additives on Thin Layers of Titanium(IV) Silicate Ion-Exchanger

JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of acetaldehyde, o-anisidine, ascorbic acid, benzoic acid, butylated hydroxyanisole, butylated...     

Introducing curcumin as an electrochemical DNA hybridization indicator and its application for detection of human interleukin-2 gene

In this paper, the application of curcumin (CU) as a non-toxic electrochemical DNA hybridization indicator was described. Hybridization investigations on a pencil graphite electrode surface as a transducer using oligonucleotides containing only one base type, including poly A, poly T, poly C, and poly G as probe and as related complementary/non-complementary sequences, showed that CU has no specific interaction with each of the oligonucleotides of DNA. Furthermore, results showed good interaction between CU and the hybridized form of oligonucleotides; thus, the extent of hybridization was evaluated based on the difference between differential pulse voltammetry (DPV) signals of CU accumulated on the probe-pencil graphite electrode (PGE) and CU accumulated on the probe-target-PGE. Then, the developed biosensor was successfully applied for the detection of short sequences of human interleukin-2 (hIL-2) gene as a model. A hybridization experiment with non-complementary oligonucleotide showed that the suggested DNA sensor responds selectively to the target. At optimized conditions, two linear ranges were obtained for hIL-2 gene, first from 50 to 1000 pM and second from 0.01 to 1 μM with a detection limit of 12 pM. 7.0) containing 20 mM NaCl.     

Simultaneous Determination of Nitrite and Hydrogen Peroxide Using Hemoglobin Modified Pencil Lead Electrode as a Novel Biosensor: Application to the Analysis of Mother’s Milk

In the present paper simultaneous determination of nitrite and hydrogen peroxide using hemoglobin modified pencil lead electrode (Hb/PLE) prepared by a simple and rapid electroless method was described. In the first part of the work the reduction of NO₂ and H₂O₂ at the modified electrode was investigated by cyclic voltammetry. Then under optimal conditions using differential pulse voltammetry, the biosensor could be used for the determination of H₂O₂ at concentration ranging from 5 to 240 M and NO₂ at concentration ranging from 10 to 240 M. The detection limits were 3×10^?6 and 5×10^?6 M, for NO₂ and H₂O₂ respectively. Differential pulse voltammetry also used for the simultaneous determination of NO₂ and H₂O₂. This modified electrode successfully used for the determination of NO₂ and H₂O₂ in tap water and mother’s milk samples.     

Detection of Human Interleukine‐2 Gene Using a Label‐Free Electrochemical DNA Hybridization Biosensor on the Basis of a Non‐Inosine Substituted Probe

The human interleukine‐2 gene (hIL‐2) is detected with a label‐free DNA hybridization biosensor using a non‐inosine substituted probe. The sensor relies on the immobilization of a 20‐mer antisense single strand oligonucleotide (chIL‐2) related to the human interleukine‐2 gene on the pencil graphite electrode (PGE) as a probe. The guanine oxidation signal was monitored using anodic differential pulse voltammetry (ADPV). The electrochemical pretreatment of the polished PGE at 1.80 V for 5 min is suggested. Then, 5 min immobilization at 0.50 V was found as the optimum condition for immobilization of the probe. The electrochemical detection of hybridization between chIL‐2 and hIL‐2 as a target was accomplished. The selectivity of the biosensor was studied using noncomplementary oligonucleotides. Diagnostic performance of the biosensor is described and the detection limit is found 36 pg/μL.     

Voltammetric Determination of Hemoglobin Using a Pencil Lead Electrode

In this paper the electrochemical behavior of hemoglobin (Hb) immobilized on a pencil lead electrode (PLE) was investigated. Immobilization of Hb on the pencil lead electrode was performed by nonelectrochemical and electrochemical methods. In phosphate buffer solution with pH 7.0 Hb showed a pair of well‐defined and nearly reversible redox waves (the anodic and cathodic peak potentials are located at ?0.18 V and ?0.22 V, respectively). The dependence of the anodic peak potential (E_pa) on the pH of the buffer solution indicated that the conversion of Hb? Fe(III)/Hb? Fe(II) is a one‐electron‐transfer reaction process coupled with one‐proton‐transfer. In addition the effect of scan rate on peak currents and peak separation potential was investigated and electrochemical parameters such as α and k_s were calculated. In the second part of this work, the ability of the electrode for determination of Hb concentration was investigated. The results showed a linear dynamic range from 0.15 to 2 µM and a detection limit of 0.11 µM. The relative standard deviation is 4.1 % for 4 successive determinations of a 1 µM Hb solution.     

Voltammetric detection of uridin diphosphate glucuronosyl transferase 1A9 (UGT1A9) gene corresponding oligonucleotide covering promoter region from −268 to −280 including (A/T) polymorphism at position −275 and optimization of the detection factors

In this study, we developed a new peptide nucleic acid (PNA) biosensor for detection of a single nucleotide polymorphism (SNP) in the UGT1A9 gene promoter region via electrochemical assay. The sensor relies on the immobilization of a 13-mer single stranded PNA probe related to the UGT1A9 gene on the Au electrode (AuE). The hybridization between the probe and its complementary sequence (DcUG275) as the target was studied by differential pulse voltammetry (DPV) of methylene blue (MB) signal. In this approach the extent of hybridization is evaluated on the basis of the difference between DPV signals of MB accumulated on the probe-AuE and MB accumulated on the probe-target-AuE. Some experimental variables affecting the performance of the biosensor including oxygen interference during the assay, probe immobilization time, probe concentration and MB accumulation time were investigated. The PNA probe modified AuE in its optimum condition was shown to be an effective sensor for the detection of hybridization and point mutations. The obtained detection limit of the utilized biosensor has been calculated as 22 nm.     

Preparation and characterization of flexible polyurethane foam nanocomposites reinforced by magnetic core-shell Fe3O4@APTS nanoparticles

Novel magnetic polyurethane flexible foam nanocomposites were synthesized by incorporation of aminopropyltriethoxysilane (APTS) functionalized magnetite nanoparticles (MNPs) via one-shot method. The functionalized MNPs (Fe₃O₄@APTS) were synthesized by co-precipitation of the Fe²⁺ and Fe³⁺ with NH₄OH and further functionalization with APTS onto the surface of MNPs by sol–gel method. The magnetic core-shell NPs were used up to 3.0 % in the foam formulation and the magnetic nanocomposites prepared successfully. The results of thermogravimetric analysis (TGA) showed an increasing in thermal stability of polyurethane nanocomposite foam at initial, 5 and 10 %, and maximum thermal decomposition temperatures by incorporation of Fe₃O₄@APTS. In addition SEM images revealed the uniformity of the foam structures and decreasing in pore sizes. Furthermore, VSM result showed super paramagnetic behavior for Fe₃O₄@APTS-PU nanocomposites.