Plant cells metabolism is known to undergo considerable reprogramming in response to static magnetic field (SMF). In the present research changes of metabolism induced by SMF and underlying mechanism(s) was investigated in suspension-cultured tobacco (Nicotiana tabacum cv. Barley 21) cells. Sugars and amino acids were monitored by HPLC, components of redox system were measured by spectrophotometer and expression of genes was evaluated by RT-PCR. Exposure to SMF decreased the adenosine triphosphate, glucose, fructose, and sucrose contents but increased hydrogen peroxide, nitric oxide, hydroxyl radical, proline, and reduced glutathione (GSH). Treatment with SMF also increased the gene expression and activity of catalase, compared to the control group. Exposure to SMF also increased the contents of phenylalanine and tyrosine, elevated the gene expression and activity of phenylalanine ammonia-lyase, and subsequently increased soluble phenolic compounds. Pretreatment of the cells with 40 µM sodium ascorbate reduced all above mentioned parameters except for nitric oxide and hydroxyl radical contents. The rate of membrane lipid peroxidation was also increased in ascorbate-pretreated cells. The results suggest a crucial role for H2O2 in triggering changes in primary and secondary metabolic pathways which result in alleviation of stress of SMF in tobacco cells. پرونده مقاله

The occurrence of antibiotic-resistant pathogenic bacteria is becoming a serious problem. The rise of multiresistance strains has forced the pharmaceutical industry to come up with new generation of more effective and potent antibiotics, therefore creating development of antivirulence compounds. Due to extensive usage of cell-to-cell bacterial communication (QS) systems to monitor the production of virulence factors, disruption of QS system results in creation of a promising strategy for the control of bacterial infection. Numerous natural quorum quenching (QQ) agents have been identified. In addition, many microorganisms are capable of producing smaller molecular QS inhibitors and/or macromolecular QQ enzymes. In present survey, anti QS activity of 1280 rhizosphere bacteria was assessed using the Pectobacterium carotovorum as AHL-donor and Chromobacterium violaceum CV026 as biosensor system. The results showed that 61 strains had highly AHL-degrading activity. Both Lux I and Lux R activity were affected by some isolates, suggesting that the rhizobacteria target both QS signal and receptor. These soil microorganisms with their anti-QS activity have the potential to be novel therapeutic agents for reducing virulence and pathogenicity of antibiotic resistant bacteria. پرونده مقاله