The role of Pro-P5C Cycle in chs mutants of Arabidopsis under cold stress

Proline metabolism is implicated in plant responses to abiotic stresses, including the chilling stress. During proline catabolism, the two-step oxidation of proline is performed by the continuous actions of proline dehydrogenase (ProDH), which produces Δ¹-pyrroline-5-carboxylate (P5C), and P5C dehydrogenase (P5CDH), which oxidizes P5C to glutamate. The Arabidopsis thaliana chilling mutants chs1 and chs2 are sensitive to chilling temperatures of 13–18°C. For a better understanding of Arabidopsis responses to chilling stress, 4-week-old wild-type (WT) and chs1 and chs2 lines, with three plants in each group, were subjected to chilling stress (13°C), cold stress (4°C), or remained under normal conditions (23°C); and several factors including the expression of ProDH2 and P5CDH genes, POX (peroxidase) and SOD (superoxide dismutase) activities, as well as MDA and proline contents were examined. Our results showed an increase in the proline content in all lines under chilling conditions. In addition, a greater expression of ProDH2 and a lower expression of P5CDH were observed, leading us to speculate a greater breakdown of proline into P5C and a consequent overproduction of ROS in the ETC cycle. The higher POX and SOD activities and a higher MDA content in chs mutants at 13°C are in line with this speculation. Finally, cold-treated plants (4°C) only showed an increase in proline levels.     

Direct chemiluminescence determination of penicillin G potassium and a chemometrical optimization approach

A highly selective and simple chemiluminescence (CL) method for determination of penicillin G potassium (PGK) was developed. In the proposed method, CL was elicited from PGK upon its oxidation with H₂O₂. The light emission was enhanced in the presence of N‐cetyl‐N,N,N‐trimethylammonium bromide (CTMAB). An experimental design, central composite design (CCD), was used to realize the optimized variables, including pH, surfactant (CTMAB) and H₂O₂ concentrations. Under optimum condition, the calibration graph was linear in the range 3.3 × 10^?3–3.3 × 10^?1 mmol/L, with a detection limit of 8.8 × 10^?4 mmol/L for PGK. The precision was calculated by analysing samples containing 1.6 × 10^?1 mmol/L PGK (n = 5) and the relative standard deviation (RSD) was 1.40%. The utility of this method was demonstrated by determining PGK in pharmaceutical formulations for injection. The proposed method was validated by a reference method. Copyright © 2011 John Wiley & Sons, Ltd.     

Electrically Assisted Liquid‐Phase Microextraction Combined With Capillary Electrophoresis for Quantification of Propranolol Enantiomers in Human Body Fluids

In this study, electromembrane extraction (EME) combined with cyclodextrin (CD)‐modified capillary electrophoresis (CE) was applied for the extraction, separation, and quantification of propranolol (PRO) enantiomers from biological samples. The PRO enantiomers were extracted from aqueous donor solutions, through a supported liquid membrane (SLM) consisting of 2‐nitrophenyl octyl ether (NPOE) impregnated on the wall of the hollow fiber, and into a 20‐μL acidic aqueous acceptor solution into the lumen of hollow fiber. Important parameters affecting EME efficiency such as extraction voltage, extraction time, pH of the donor and acceptor solutions were optimized using a Box‐Behnken design (BBD). Then, under these optimized conditions, the acceptor solution was analyzed using an optimized CD‐modified CE. Several types of CD were evaluated and best results were obtained using a fused‐silica capillary with ammonium acetate (80 mM, pH 2.5) containing 8 mM hydroxypropyl‐β‐CD as a chiral selector, applied voltage of 18 kV, and temperature of 20°C. The relative recoveries were obtained in the range of 78–95%. Finally, the performance of the present method was evaluated for the extraction and determination of PRO enantiomers in real biological samples. Chirality 26:260–267, 2014. © 2014 Wiley Periodicals, Inc.     

Thidiazuron induced efficient in vitro organogenesis and regeneration of Scutellaria bornmuelleri: an important medicinal plant

In Vitro Cellular & Developmental Biology - Plant -