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111.
Bharati Pandey Sonam Grover Sukriti Goyal Salma Jamal Aditi Singh Jagdeep Kaur 《Journal of biomolecular structure & dynamics》2019,37(1):20-35
Streptomycin was the first antibiotic used for the treatment of tuberculosis by inhibiting translational proof reading. Point mutation in gidB gene encoding S-adenosyl methionine (SAM)-dependent 7-methylguanosine (m7G) methyltransferase required for methylation of 16S rRNA confers streptomycin resistance. As there was no structural substantiation experimentally, gidB protein model was built by threading algorithm. In this work, molecular dynamics (MD) simulations coupled with binding free energy calculations were performed to outline the mechanism underlying high-level streptomycin resistance associated with three novel missense mutants including S70R, T146M, and R187M. Results from dynamics analyses suggested that the structure distortion in the binding pocket of gidB mutants modulate SAM binding affinity. At the structural level, these conformational changes bring substantial decrease in the number of residues involved in hydrogen bonding and dramatically reduce thermodynamic stability of mutant gidB–SAM complexes. The outcome of comparative analysis of the MD simulation trajectories revealed lower conformational stability associated with higher flexibility in mutants relative to the wild-type, turns to be major factor driving the emergence of drug resistance toward antibiotic. This study will pave way toward design and development of resistant defiant gidB inhibitors as potent anti-TB agents. 相似文献
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Mohammad Salma Isabelle Engelmann-Sylvestre Myriam Collin Jacques Escoute Marc Lartaud Jung-Yoon Yi Haeng-Hoon Kim Jean-Luc Verdeil Florent Engelmann 《Protoplasma》2014,251(3):649-659
In this work, we studied the impact of the successive steps of the droplet-vitrification protocol technique employed for cryopreservation of Rubia akane hairy roots on the features of cortical, pericycle and endoderm cells of apical and central root segments, using histology techniques and combining qualitative and quantitative observations. In apical segments, plasmolysis (22–71 %, depending on cell type) was observed only after the loading treatment and did not increase after the following steps of the protocol. By contrast, in central segments, plasmolysis (39–45 %) was already observed after the sucrose pretreatment; it increased to 54–68 %, depending on cell type, after the loading treatment, but no further changes were noted after treatment with the vitrification solution. After liquid nitrogen exposure and unloading treatment, deplasmolysis was more rapid in apical segments, with cortical and pericycle cells having retrieved their original features. In central segments, only cortical cells had retrieved their original features and endoderm and pericycle cells were still highly plasmolysed. Nuclei were more strongly impacted by the cryopreservation protocol in central segments, where they displayed a highly condensed nucleoplasm from the loading treatment onwards and had not retrieved their original aspect after the unloading treatment. By contrast, nuclei had a much less condensed nucleoplasm in cells of apical segments, and they had retrieved their original aspect after the unloading treatment. 相似文献
114.
Salma Gul Shah W. Thomas Shier Jamaluddin Nawaz Tahir Abdul Hameed Safia Ahmad Naeem Ali 《Archives of microbiology》2014,196(4):267-278
A newly isolated fungus Penicillium verruculosum SG was evaluated for the production and characterization of bioactive colored secondary metabolites using solid-state fermentation along with their cytotoxic activities against normal and cancer cell lines. Logical fragmentation pattern following column chromatography, thin layer chromatography and liquid chromatography and mass spectrometry of crude culture filtrate of fungus revealed the presence of different polyketide pigments and other bioactive compounds. Cytotoxicity of the selected colored fractions of fungal filtrate containing different compounds revealed IC50 (μg/ml) values ranging from 5 to 100. It was significantly higher in case of orevactaene (5 + 0.44) and monascorubrine followed by pyripyropene (8 + 0.63) against cancer cell line KA3IT. Overall, these compounds considerably showed less toxicity toward normal cell lines NIH3T3, HSCT6, HEK293 and MDCK. XRD of a yellow crystalline compound (224.21 m/z) confirmed its 3-dimensional structure as phenazine 1 carboxylic acid (C13H8N2O2) (broad spectrum antibiotic), and it is first time reported in fungi. 相似文献
115.
Kaouthar Feki Francisco J. Quintero Habib Khoudi Eduardo O. Leidi Khaled Masmoudi Jose M. Pardo Faiçal Brini 《Plant cell reports》2014,33(2):277-288
Key message
Expression of a truncated form of wheat TdSOS1 in Arabidopsis exhibited an improved salt tolerance. This finding provides new hints about this protein that can be considered as a salt tolerance determinant.Abstract
The SOS signaling pathway has emerged as a key mechanism in preserving the homeostasis of Na+ and K+ under saline conditions. We have recently identified and functionally characterized, by complementation studies in yeast, the gene encoding the durum wheat plasma membrane Na+/H+ antiporter (TdSOS1). To extend these functional studies to the whole plant level, we complemented Arabidopsis sos1-1 mutant with wild-type TdSOS1 or with the hyperactive form TdSOS1?972 and compared them to the Arabidopsis AtSOS1 protein. The Arabidopsis sos1-1 mutant is hypersensitive to both Na+ and Li+ ions. Compared with sos1-1 mutant transformed with the empty binary vector, seeds from TdSOS1 or TdSOS1?972 transgenic plants had better germination under salt stress and more robust seedling growth in agar plates as well as in nutritive solution containing Na+ or Li+ salts. The root elongation of TdSOS1?972 transgenic lines was higher than that of Arabidopsis sos1-1 mutant transformed with TdSOS1 or with the endogenous AtSOS1 gene. Under salt stress, TdSOS1?972 transgenic lines showed greater water retention capacity and retained low Na+ and high K+ in their shoots and roots. Our data showed that the hyperactive form TdSOS1?972 conferred a significant ionic stress tolerance to Arabidopsis plants and suggest that selection of hyperactive alleles of the SOS1 transport protein may pave the way for obtaining salt-tolerant crops. 相似文献116.
Determination of amlodipine using terbium‐sensitized luminescence in the presence of europium(III) as a co‐luminescence reagent 下载免费PDF全文
Salma M. Z. Al‐Kindy Abdalla Al‐Snedi Fakhr Eldin O. Suliman Haidar A. J. Al‐Lawati 《Luminescence》2014,29(6):657-662
A sensitive time‐resolved luminescence method for the determination of amlodipine (AM) in methanol and in aqueous solution is described. The method is based on the luminescence sensitization of terbium (Tb3+) by formation of a ternary complex with AM in the presence of tri‐n‐octylphosphine oxide (TOPO) as co‐ligand, dodecylbenzenesulfate as surfactant and europium ion as a co‐luminescence reagent. The signal for Tb–AM–TOPO is monitored at λex = 242 nm and λem = 550 nm. Optimum conditions for the formation of the complex in aqueous system were 0.015 m Tris (hydroxylmethyl) amino methane buffer, pH 9.0, TOPO (1.0 × 10–4 m ), Eu3+ (2.0 × 10–7 m ), dodecylbenzenesulfate (0.14%) and 6.0 × 10–5 m of Tb3+, which allows the determination of 10–50 ppb of AM with a limit of detection of 1.2 ppb. The relative standard deviations of the method range between 0.1 and 0.2% indicated excellent reproducibility of the method. The proposed method was successfully applied for the assay of AM in pharmaceutical formulations and in plasma samples. Average recoveries of 98.5 ± 0.2% and 95.2 ± 0.2% were obtained for AM in tablet and plasma samples respectively. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
117.
Salma Ali Al‐Tamimi Nawal Ahmad Alarfaj Fatma Ahmed Aly Amal Mohammed Al‐Mohaimeed 《Luminescence》2014,29(2):127-131
A simple, rapid and highly sensitive spectrofluorimetric method was developed for determination of gemifloxacin mesylate (GFX) in tablets. The method is based on measuring the native fluorescence of GFX in isopropanol at 400 nm after excitation at 272 nm. The fluorescence–concentration plot was rectilinear over the range of 0.01–0.50 µg/mL with a lower detection limit of 1.19 ng/mL and quantification limit of 3.6 ng/mL. The method was fully validated and successfully applied to the determination of GFX tablets with an average percentage recovery of 99.65 ± 0.532. The method was extended to the stability study of GFX. The drug was exposed to acidic, alkaline, oxidative and photolytic degradation according to International Conference on Harmonization guidelines. The rate of GFX degradation was found at its highest in acidic conditions, and in its lowest in the neutral one. However, it was stable under dry heat and photolytic degradation conditions. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Wasti S Mimouni H Smiti S Zid E Ben Ahmed H 《Omics : a journal of integrative biology》2012,16(4):200-207
In Tunisia, like in the other countries of the Mediterranean, tomato is ranked among the important vegetables in the economic sphere. Tunisia ranks as the first consumer of this vegetable in the world. However, tomatoes are exposed to multiple environmental stresses. In particular, salinity is the most stressful limiting factor to productivity. Salt tolerance of the tomato is susceptible to be ameliorated by genetic and physiologic ways. Salicylic acid (SA), a plant phenolic, is now considered as a hormone-like endogenous regulator, and its role in the defense mechanisms against biotic and abiotic stressors has been well documented. So, the aim of this study was to investigate the impact of exogenous application of SA (0.01 mM) on growth, nutritional behavior, and some metabolic parameters (total chlorophyll, soluble sugars, proline, and proteins) of tomato plants cv. Moneymaker exposed to NaCl (100 mM). Our results showed that the application of 0.01 mM SA to tomato plants via root drenching attenuate the depressive effect of salinity on plants. This amelioration results in stimulation of growth and development of plant. Under stress conditions, SA-treated plants exhibited more accumulation of photosynthetic pigments and K(+) contents. Thus, SA induces an increase in soluble sugars in roots and leaves; also, we noted the increase of proteins only in roots. Overall, the adverse effects of salt stress tomato plants were alleviated by the exogenous application of SA at vegetative stage, which upregulated nutrition and the accumulation of some organic solutes and osmoprotectors such sugars, proline, and proteins. So salicylic acid can be greatly used to enhance salt tolerance of tomato plants. 相似文献
120.
Salma Khan Jessica M. S. Jutzy Malyn May A. Valenzuela David Turay Jonathan R. Aspe Arjun Ashok Saied Mirshahidi Dan Mercola Michael B. Lilly Nathan R. Wall 《PloS one》2012,7(10)