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41.
42.
Ramtin Vamenani Heshmatollah Rahimian Seyyed Mohammad Alavi Ali Pakdin Parizi Tarlan Mirza Razzaz 《Journal of Phytopathology》2019,167(9):484-489
Hop stunt viroid as the causal agent of cachexia disease has detected from citrus trees in different areas in Iran. Although cachexia has not been reported as a decline disease for citrus trees, it can impair crop quality and reduce plant yields. This study was undertaken to molecularly detect HSVd among different commercial citrus cultivars and determine genetic diversity of this viroid in Mazandaran province of Iran. Sampling was performed from symptomatic and symptomless citrus cultivars in Mazandaran province. HSVd specific primers were used for molecular detection. SSCP and sequencing were applied to assay HSVd genetic diversity. Results showed the detection of HSVd in all symptomatic Satsuma (25 out of 25), Clementine (25 out of 25), sweet lime (20 out of 20) and sweet orange cv. Valencia (7 out of 7), as well as, 31% (14 out of 22), 100% (12 out of 12) and 33% (5 out of 15) of page mandarin, lemon and grapefruit trees, respectively. 10 different HSVd genomes were identified by sequencing the SSCP profiles among which HSVd‐IR1 had the most frequency. 相似文献
43.
Free radical damage to cultured porcine aortic endothelial cells and lung fibroblasts: Modulation by culture conditions 总被引:5,自引:0,他引:5
Clark T. Bishop Zermeena Mirza James D. Crapo Bruce A. Freeman 《In vitro cellular & developmental biology. Plant》1985,21(4):229-236
Summary Culture conditions modulating cell damage from xanthine plus xanthine oxidase-derived partially reduced oxygen species were
studied. Porcine thoracic aorta endothelial cells and porcine lung fibroblasts were maintained in monolayer culture. Cells
were prelabeled with51Cr before xanthine plus xanthine oxidase exposure. Endothelial cells showed 30 to 100% more lysis than fibroblasts and thus
seemed more sensitive to this oxidant stress. The effect of cell culture age, as indicated by population doubling level (PDL),
was examined. Response of low PDL endothelial cells and fibroblasts subjected to oxidant stress was compared with the response
of PDL 15 cells. Both low PDL endothelial cells and fibroblasts responded differently to the lytic effect of xanthine oxidase-derived
free radicals than did higher PDL cells. Specific activities of the antioxidant enzymes catalase, managanese superoxide dismutase,
copper-zinc superoxide dismutase, glutathione peroxidase, and glucose-6-phosphate dehydrogenase were measured in both low
and high PDL fibroblasts and endothelial cells. Antioxidant enzyme specific activities could only partially explain the differences
in response to oxidant stress between fibroblasts and endothelial cells and between low and high PDL cells. Cell culture medium
composition modulated the rate of production, and relative proportions of xanthine plus xanthine oxidase-derived partially
reduced species of oxygen, i.e. superoxide, hydrogen peroxide, and hydroxyl radical. Serum content of medium was important
in modulating free radical generation; superoxide production rates decreased 32%, H2O2 became undetectable, and hydroxyl radical generation decreased 54% in the presence of 10% serum. The medium protein and iron
content also modulated free radical generation. The data suggest that cell culture media constituents, cell type, and cell
culture age greatly affect in vitro response of cells subjected to oxidant stress.
Research supported by American Lung Association Fellowship Training Grant and Research Training Grant, the R. J. Reynolds
Corporation, and National Institutes of Health Grants HL29784 and 1 HL 23805. 相似文献
44.
Homoserine transacetylase catalyzes one of the required steps in the biosynthesis of methionine in fungi and several bacteria. We have determined the crystal structure of homoserine transacetylase from Haemophilus influenzae to a resolution of 1.65 A. The structure identifies this enzyme to be a member of the alpha/beta-hydrolase structural superfamily. The active site of the enzyme is located near the end of a deep tunnel formed by the juxtaposition of two domains and incorporates a catalytic triad involving Ser143, His337, and Asp304. A structural basis is given for the observed double displacement kinetic mechanism of homoserine transacetylase. Furthermore, the properties of the tunnel provide a rationale for how homoserine transacetylase catalyzes a transferase reaction vs hydrolysis, despite extensive similarity in active site architecture to hydrolytic enzymes. 相似文献
45.
Asim Mehmood Umal Baneen Ahmad Zaheer Muhammad Wasim Sajid Abrar Hussain Shahzad Saleem Qudsia Yousafi Hamid Rashid Hassan Riaz Awais Ihsan Farrukh Jamil Yasar Sajjad Nageena Zahid Muhammad Shahzad Anjam Muhammad Arshad Zeenat Mirza Sajjad Karim Mahmood Rasool 《Saudi Journal of Biological Sciences》2019,26(7):1485-1491
ObjectivePhosphorous is an essential micronutrient of plants and involved in critical biological functions. In nature, phosphorous is mostly present in immobilized inorganic mineral and in the fixed organic form including phytic acid and phosphoesteric compounds. However, the bioavailability of bound phosphorous could be enhanced by the use of phosphate solubilizing microorganisms such as bacteria and fungi. The phytases are widespread in an environment and have been isolated from different sources comprising bacteria and fungi.MethodologyIn current studies, we show the successful use of gamma rays and EMS (Ethyl Methane Sulphonate) mutagenesis for enhanced activity of phytases in a fungal strain Sporotrichum thermophile.ResultsWe report an improved strain ST2 that could produce a clear halo zone around the colony, up to 24 mm. The maximum enzymatic activity was found of 382 U/mL on pH 5.5. However, the phytase activity was improved to 387 U/ml at 45 °C. We also report that the mutants produced through EMS showed the greater potential for phytase production.ConclusionThe current study highlights the potential of EMS mutagenesis for strain improvement over physical mutagens. 相似文献
46.
Malai Haniti S.A. Hamid Aminul Huq Mirza Boujemaa Moubaraki 《Inorganica chimica acta》2009,362(10):3648-41
New copper(II) complexes of general empirical formula, [Cu(NNS)X] (NNS = anionic forms of the 2-acetylpyrazine Schiff bases of S-methyl- and S-benzyldithiocarbazate, Hapsme and Hapsbz) and X = Cl−, Br−, NCS− and NO3− have been synthesized and characterized. X-ray crystal structures of the free ligand, Hapsbz and the complexes, [Cu(apsbz)(NO3)]∞, [Cu(apsme)(NCS)]2 and [Cu(apsme)Cl]2 have been determined. In the solid state, the Schiff base, Hapsbz remains in its thione tautomeric form with the thione sulfur atom trans to the azomethine nitrogen atom. X-ray diffraction shows that the [Cu(apsbz)(NO3)]∞ complex is a novel coordination polymer in which one of the nitrogen atoms of the pyrazine ring bridges two adjacent copper(II) ions. The Schiff base is coordinated to the copper(II) ion in its iminothiolate form via the thiolate sulfur atom, the azomethine nitrogen atom and one of the pyrazine nitrogen atoms, the overall geometry of each copper atom in the polymer being close to a square-pyramid. The complexes, [Cu(apsme)X]2 (X = NCS−, Cl−) are dimers in which each copper atom adopts a five-coordinate near square-pyramidal geometry with an N3S2 coordination environment. The Schiff base coordinates as a uninegatively charged tridentate ligand chelating via the pyridine and azomethine nitrogen atoms and the thiolate sulfur atoms. A nitrogen atom of a unidentate thiocayanate or chloride ligand and a bridging sulfur atom from a second ligand completes the coordination sphere. Room temperature μeff values for the complexes in the solid state are in the range 1.70-2.0 μB typical of uncoupled or weakly coupled Cu(II) centres. Variable temperature susceptibility studies show that the chain complex displays weak ferromagnetic coupling across the pyrazine bridges, while the S-bridged dinuclear compounds display either weak ferromagnetic or weak antiferromagnetic coupling that relates to subtle bridging geometry differences. EPR studies of frozen DMF solutions give rather similar g and ACu values for all compounds indicative of Cu(dx2-y2) ground state orbitals on the Cu centers. 相似文献
47.
Alycia C. R. Lackey Alyssa C. Murray Nadia A. Mirza Thomas H. Q. Powell 《Journal of evolutionary biology》2023,36(6):882-892
The pace of divergence and likelihood of speciation often depends on how and when different types of reproductive barriers evolve. Questions remain about how reproductive isolation evolves after initial divergence. We tested for the presence of sexual isolation (reduced mating between populations due to divergent mating preferences and traits) in Rhagoletis pomonella flies, a model system for incipient ecological speciation. We measured the strength of sexual isolation between two very recently diverged (~170 generations) sympatric populations, adapted to different host fruits (hawthorn and apple). We found that flies from both populations were more likely to mate within than between populations. Thus, sexual isolation may play an important role in reducing gene flow allowed by early-acting ecological barriers. We also tested how warmer temperatures predicted under climate change could alter sexual isolation and found that sexual isolation was markedly asymmetric under warmer temperatures – apple males and hawthorn females mated randomly while apple females and hawthorn males mated more within populations than between. Our findings provide a window into the early speciation process and the role of sexual isolation after initial ecological divergence, in addition to examining how environmental conditions could shape the likelihood of further divergence. 相似文献
48.
Davies AF Mirza G Sekhon G Turnpenny P Leroy F Speleman F Law C van Regemorter N Vamos E Flinter F Ragoussis J 《Human genetics》1999,104(1):64-72
Deletions of the short arm of chromosome 6 are relatively rare, the main features being developmental delay, craniofacial
malformations, hypotonia, and defects of the heart and kidney, with hydrocephalus and eye abnormalities occurring in some
instances. We present the molecular cytogenetic investigation of six cases with 6p deletions and two cases with unbalanced
translocations resulting in monosomy of the distal part of 6p. The breakpoints of the deletions have been determined accurately
by using 55 well-mapped probes and fluorescence in situ hybridization (FISH). The cases can be grouped into two distinct categories:
interstitial deletions within the 6p22–p24 segment and terminal deletions within the 6p24–pter segment. Characteristics correlating
with specific regions are: short neck, clinodactyly or syndactyly, brain, heart and kidney defects with deletions within 6p23–p24;
and corneal opacities/iris coloboma/Rieger anomaly, hypertelorism and deafness with deletions of 6p25. The two cases with
unbalanced translocations presented with a Larsen-like syndrome including some characteristics of the 6p deletion syndrome,
which can be explained by the deletion of 6p25. Such investigation of cytogenetic abnormalities of 6p using FISH techniques
and a defined set of probes will allow a direct comparison of reported cases and enable more accurate diagnosis as well as
prognosis in patients with 6p deletions.
Received: 29 July 1998 / Accepted: 28 October 1998 相似文献
49.
Spangfort MD Mirza O Ipsen H Van Neerven RJ Gajhede M Larsen JN 《Journal of immunology (Baltimore, Md. : 1950)》2003,171(6):3084-3090
Specific allergy vaccination is an efficient treatment for allergic disease; however, the development of safer vaccines would enable a more general use of the treatment. Determination of molecular structures of allergens and allergen-Ab complexes facilitates epitope mapping and enables a rational approach to the engineering of allergen molecules with reduced IgE binding. In this study, we describe the identification and modification of a human IgE-binding epitope based on the crystal structure of Bet v 1 in complex with the BV16 Fab' fragment. The epitope occupies approximately 10% of the molecular surface area of Bet v 1 and is clearly conformational. A synthetic peptide representing a sequential motif in the epitope (11 of 16 residues) did not inhibit the binding of mAb BV16 to Bet v 1, illustrating limitations in the use of peptides for B cell epitope characterization. The single amino acid substitution, Glu(45)-Ser, was introduced in the epitope and completely abolished the binding of mAb BV16 to the Bet v 1 mutant within a concentration range 1000-fold higher than wild type. The mutant also showed up to 50% reduction in the binding of human polyclonal IgE, demonstrating that glutamic acid 45 is a critical amino acid also in a major human IgE-binding epitope. By solving the three-dimensional crystal structure of the Bet v 1 Glu(45)-Ser mutant, it was shown that the change in immunochemical activity is directly related to the Glu(45)-Ser substitution and not to long-range structural alterations or collapse of the Bet v 1 mutant tertiary structure. 相似文献
50.
Akbar Ali M Mirza AH Butcher RJ Tarafder MT Keat TB Ali AM 《Journal of inorganic biochemistry》2002,92(3-4):141-148
Palladium(II) and platinum(II) complexes of general empirical formula, [M(NS)(2)] (NS=uninegatively charged acetone Schiff bases of S-methyl- and S-benzyldithiocarbazate; M=Pt(II) and Pd(II)) have been prepared and characterized by a variety of physicochemical techniques. Based on conductance, IR and electronic spectral evidence, a square-planar structure is assigned to these complexes. The crystal and molecular structure of the [Pd(asme)(2)] complex (asme=anionic form of the acetone Schiff base of S-methyldithiocarbazate) has been determined by X-ray diffraction. The complex has a distorted cis-square planar structure with the ligands coordinated to the palladium(II) ions as uninegatively charged bidentate NS chelating agents via the azomethine nitrogen and the mercaptide sulfur atoms. The distortion from a regular square-planar geometry is attributed to the restricted bite angles of the ligands. Antimicrobial tests indicate that the Schiff bases exhibit strong activities against the pathogenic bacteria, Bacillus subtilis (mutant defective DNA repair), methicillin-resistant Staphylococcus aureus, B. subtilis (wild type) and Pseudomonas aeruginosa and the fungi, Candida albicans (CA), Candida lypotica (2075), Saccharomyces cerevisiae (20341) and Aspergillus ochraceous (398)-the activities exhibited by these compounds being greater than that of the standard antibacterial and antifungal drugs, streptomycin and nystatin, respectively. The palladium(II) and platinum(II) complexes are inactive against most of these organisms but, the microbe, Pseudomonas aeruginosa shows strong sensitivity to the platinum(II) complexes. Screening of the compounds for their cytotoxicities against T-lymphoblastic leukemia cancer cells has shown that the acetone Schiff base of S-methyldithiocarbazate (Hasme) exhibits a very weak activity, whereas the S-benzyl derivative (Hasbz) is inactive. However, the palladium(II) complexes exhibit strong cytotoxicities against this cancer; their activities being more than that of the standard anticancer drug, tamoxifen. The [Pt(asme)(2)] complex exhibits a very weak cytotoxicity, whereas [Pt(asbz)(2)] is inactive against leukemic cells. 相似文献