Monte Carlo-based determination of radiation leakage dose around a dedicated IOERT accelerator

Radiation and Environmental Biophysics - Evaluating the stray radiation around medical electron accelerators is a mandatory issue. Surveying the radiation leakage dose is important for patients,...     

A crystallographic and theoretical study of an (E)-2-Hydroxyiminoethanone derivative: prediction of cyclooxygenase inhibition selectivity of stilbenoids by MM-PBSA and the role of atomic charge

We recently reported that the hydroxyiminoethanone derivative, (E)-OXM, behaves as a highly selective COX-1 inhibitor (COX-1 SI = 833), and also an interesting scaffold with unique characteristics. In the current study, a comprehensive crystallographic and computational study was performed to elucidate its conformational stability and pharmacological activity. Its conformational energy was studied at the B3LYP/6-311G** level of theory and compared to the single-crystal X-ray diffraction data. In addition, computational studies of three structurally different stilbenoid derivatives used as selective COX-1 or COX-2 inhibitors were undertaken to predict their COX selectivity potentials. Flexible docking was performed for all compounds at the active site of both COX-1 and COX-2 enzymes by considering some of the key residues as flexible during the docking operation. In the next step, molecular dynamic simulation and binding free energy calculations were performed by MM-PBSA. Final results were found to be highly dependent on the atomic charges of the inhibitors and the choice of force field used to calculate the atomic charges. The binding conformation of the hydroxyiminoethanone derivative is highly correlated with the type of COX isoform inhibited. Our predictive approach can truly predict the cyclooxygenase inhibition selectivity of stilbenoid inhibitors.     

Improvement of tissue culture,genetic transformation,and applications of biotechnology to Brassica

Development of in vitro plant regeneration method from Brassica explants via organogenesis and somatic embryogenesis is influenced by many factors such as culture environment, culture medium composition, explant sources, and genotypes which are reviewed in this study. An efficient in vitro regeneration system to allow genetic transformation of Brassica is a crucial tool for improving its economical value. Methods to optimize transformation protocols for the efficient introduction of desirable traits, and a comparative analysis of these methods are also reviewed. Hence, binary vectors, selectable marker genes, minimum inhibitory concentration of selection agents, reporter marker genes, preculture media, Agrobacterium concentration and regeneration ability of putative transformants for improvement of Agrobacterium-mediated transformation of Brassica are discussed.     

Genetic diversity of soft rot strains of Pectobacterium,isolated from different hosts,using ISSR marker

Pectobacteria are one of the most important groups of plant pathogenic bacteria and have been reported in many countries including Iran. Thirty-five Iranian strains of pectobacteria were isolated from potato, cabbage, sugar beet, pepper, carrot, onion, cucumber, turnip and tomato host plants cultivated in Fars province of Iran, in 2013. The genetic diversity among the strains was evaluated using ISSR marker. The tested strains were rod-shape, motile with peritrichous flagella, gram-negative, facultative anaerobes, oxidase-negative, catalase-positive, and were able to cause potato rot, while they could not induce hypersensitive reaction on tobacco leaves. Based on phenotypic criteria, the isolated strains were categorised into three groups. The strains of first, second and third groups were related to Pectobacterium carotovorum subsp. carotovorum, Pectobacterium betavascularum and Dickeya chrysanthemi, respectively. According to ISSR assay, the primers that used in this assay showed significant diversity among the strains and the specific primers GTGC4, GAGC4 and GTG5 confirmed the classification.     

Optimization of simultaneous production of tyrosinase and laccase by Neurospora crassa

Increasing demand for efficient and environmentally benign oxidation technologies has resulted in a focus on the use of oxidoreductases. Laccases and tyrosinases, which utilize molecular oxygen and produce water as by-product, are particularly attractive. Simultaneous production of laccase and tyrosinase was studied in Neurospora crassa FGSC #321 as the fungal strain which has the ability to produce tyrosinase intracellularly while producing laccase extracellularly. Using one-variable-at-a-time experiments and a Taguchi orthogonal L9 array demonstrated that a Vogel minimal medium containing 2.5% sucrose at pH 6.5 and 25?°C with no agitation or oxygen purging were the optimum conditions for N. crassa FGSC #321 growth. Conditions were adjusted to obtain the highest laccase and tyrosinase production. Results indicate that the control mechanisms for the production of both enzymes in N. crassa FGSC #321 are similar but not necessarily identical. Results revealed that transferring the harvested cells from the growth medium into the phosphate buffer (pH 6.8, 0.1M) containing cycloheximide (2?μM) and fluorouracil (2?mM) and increasing the temperature to 30?°C were the best conditions for simultaneous production of laccase and tyrosinase (1278 and 410?U/g of biomass, respectively). Nonetheless, starvation at 35?°C is proposed as the most cost-effective means for inducing laccase. The N. crassa laccase was characterized by using its molecular weight, pI value, optimal pH and temperature and stability.