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961.
962.
Leticia Escudero Mahmoud Al-Refai Cristina Nieto Hartmut Laatsch Francisco Malpartida Elena M. Seco 《PloS one》2015,10(8)
The rimJ gene, which codes for a crotonyl-CoA carboxylase/reductase, lies within the biosynthetic gene cluster for two polyketides belonging to the polyene macrolide group (CE-108 and rimocidin) produced by Streptomyces diastaticus var. 108. Disruption of rimJ by insertional inactivation gave rise to a recombinant strain overproducing new polyene derivatives besides the parental CE-108 (2a) and rimocidin (4a). The structure elucidation of one of them, CE-108D (3a), confirmed the incorporation of an alternative extender unit for elongation step 13. Other compounds were also overproduced in the fermentation broth of rimJ disruptant. The new compounds are in vivo substrates for the previously described polyene carboxamide synthase PcsA. The rimJ disruptant strain, constitutively expressing the pcsA gene, allowed the overproduction of CE-108E (3b), the corresponding carboxamide derivative of CE-108D (3a), with improved pharmacological properties. 相似文献
963.
Mohamed F. Sallam Azzam M. Al Ahmed Mahmoud S. Abdel-Dayem Mohamed A. R. Abdullah 《PloS one》2013,8(6)
BackgroundThe mosquito, Culex tritaeniorhynchus Giles is a prevalent and confirmed Rift Valley Fever virus (RVFV) vector. This vector, in association with Aedimorphus arabiensis (Patton), was responsible for causing the outbreak of 2000 in Jazan Province, Saudi Arabia.Conclusion/SignificanceThis model is a first step in understanding the spatial distribution of Cx. tritaeniorhynchus and consequently the risk of RVFV in Saudi Arabia and to assist in planning effective mosquito surveillance and control programs by public health personnel and researchers. 相似文献
964.
In this study, we investigate the possible cytotoxic effects of different Nigella sativa seed extracts on human MCF-7 breast cancer cells and screening the effects of a wide range of extracts concentrations and their application as an adjuvant therapy to doxorubicin. The results obtained showed that the cytotoxic solvent dimethyl sulfoxide can be used for permeation assay in concentration range 697.5–0.341 mmol/ml without affecting the viability of MCF-7 cells. N. sativa lipid extract is cytotoxic to MCF-7 cells with LC50 of 2.72 ± 0.232 mg/ml, while its aqueous extract cytotoxicity exhibited when the applied concentration is high as ≈ 50 mg/ml. The results of this study reveal for the first time that low concentrations of aqueous extract of the seed has a hormetic rather than cytotoxic effect. It is also possible to use cell culture medium or bovine serum to dilute the oil extract for the permeation assay. In conclusion, N. sativa aqueous extract should not be used as antitumor compound by its own. The oil is a promising antitumor compound and its cytotoxicity was greatly enhanced with its nanoemulsion formulation. Antitumor activity of doxorubicin was enhanced, as a function of time, when N. sativa extracts were involved as adjunct therapeutic compounds. Adding doxorubicin to the prepared lipid nanoemulsion has a beneficial impact to their bioactivity. These doxorubicin—N. sativa lipid nanoemulsion are promising and potential therapeutic modality. 相似文献
965.
Molecular characterization of intact, but cryptic, flagellin genes in the genus Shigella 总被引:6,自引:0,他引:6
Akira Tominaga Mohamed Abdel-Hakim Mahmoud Takafumi Mukaihara Masatoshi Enomoto 《Molecular microbiology》1994,12(2):277-285
Flagellin genes (fliC) were detected in two species of the genus Shigella. The fliCSF gene cloned from Shigella flexneri produced normal-type flagella in an Escherichia coli δ fliC strain while the fliCSS genes from two Shigella sonnei strains produced curly-type flagella and their expression is repressible by Salmonella FljA repressor. The fliCSF gene (1650bp) shared high similarity with the E. coli fliCE gene not only in the 5′ and 3′ constant sequences but also in the upstream and downstream sequences. The fliCS genes (1572 bp) shared high similarity with the Salmonella typhimurium fliCs gene in the operator and 3’constant sequences and also shared high similarity with the fliCE gene in the downstream sequence, suggesting that the fliC gene has undergone horizontal transfer and recombination. Differences In nucleotide sequences of the central variable regions among the four fliC genes, including fliCE and fliCS, suggest that they started differentiation in each lineage approximately 80 million years ago. Loss of motility in Shigella seems to be evolutionarily a recent event. 相似文献
966.
Catalysts for UHMWPE and UHMWPE-copolymers 总被引:1,自引:0,他引:1
Robert L. Jones Jr. Mahmoud Z. Armoush Michael Elder Jeffrey Sullivan 《Inorganica chimica acta》2010,364(1):275-281
Classic inorganic and more recent organometallic compounds capable of polymerizing ethylene to ultra high molecular are compared. Activated catalysts showed varying degrees of productivity when challenged with co-monomers. The general activity trend followed TiCl3 < Mg/Si-TiCl3 < metallocenes. A new phenoxyimine catalyst complex N-(3,5-diiodosalicylidene)cycloheptylamine titanium dichloride was useful in making UHMWPE and compared to previously reported phenoxyimine catalyst structures capable of living polyolefin polymerizations. 相似文献
967.
Mongolian gerbils and Wistar rats were inoculated orally with 240 and 2,500 Toxocara cati embryonated eggs, respectively, to evaluate the larval recovery in different tissues and organs, such as the liver, lungs, heart, kidney, and skeletal muscles after 5, 30, 49, 70, and 92 days post-infection (PI). Larval recovery rates were 1.7-30.0% in Mongolian gerbils on days 5-92 PI and 0.2-3.8% in rats on the same days. These results indicate that Mongolian gerbils and Wistar rats are suitable experimental paratenic hosts for the study of neurological toxocariasis as well as visceral toxocariasis. 相似文献
968.
In this paper a new method based on artificial neural networks (ANN), is introduced for identifying pathogenic antibodies in Systemic Lupus Erythmatosus (SLE). dsDNA binding antibodies have been implicated in the pathogenesis of this autoimmune disease. In order to identify these dsDNA binding antibodies, the protein sequences of 42 dsDNA binding and 608 non-dsDNA binding antibodies were extracted from Kabat database and encoded using a physicochemical property of their amino acids namely Hydrophilicity. Encoded antibodies were used as the training patterns of a general regression neural network (GRNN). Simulation results show that the accuracy of proposed method in recognizing dsDNA binding antibodies is 83.2%. We have also investigated the roles of the light and heavy chains of anti-dsDNA antibodies in binding to DNA. Simulation results concur with the published experimental findings that in binding to DNA, the heavy chain of anti-dsDNA is more important than their light chain. 相似文献
969.
Rahman LN Chen L Nazim S Bamm VV Yaish MW Moffatt BA Dutcher JR Harauz G 《Biochimie et biologie cellulaire》2010,88(5):791-807
Dehydrins are intrinsically disordered (unstructured) proteins that are expressed in plants experiencing stressful conditions such as drought or low temperature. Dehydrins are typically found in the cytosol and nucleus, but also associate with chloroplasts, mitochondria, and the plasma membrane. Although their role is not completely understood, it has been suggested that they stabilize proteins or membrane structures during environmental stress, the latter association mediated by formation of amphipathic α-helices by conserved regions called the K-segments. Thellungiella salsuginea is a crucifer that thrives in the Canadian sub-Arctic (Yukon Territory) where it grows on saline-rich soils and experiences periods of both extreme cold and drought. We have cloned and expressed in Escherichia coli two dehydrins from this plant, denoted TsDHN-1 (acidic) and TsDHN-2 (basic). Here, we show using transmission-Fourier transform infrared (FTIR) spectroscopy that ordered secondary structure is induced and stabilized in these proteins by association with large unilamellar vesicles emulating the lipid compositions of plant plasma and organellar membranes. Moreover, this induced folding is enhanced at low temperatures, lending credence to the hypothesis that dehydrins stabilize plant outer and organellar membranes in conditions of cold. 相似文献
970.
Mahmoud Sitohy Bernard Besse Sylviane Billaudel Thomas Haertlé Jean-Marc Chobert 《Probiotics and antimicrobial proteins》2010,2(2):104-111
Antiviral activity of methylated β-lactoglobulin (Met-BLG) against H3N2 infected into MDCK cell lines depended on concentration of Met-BLG, viral load, and duration of infection. IC50% of the hemagglutination activity for 1 and 0.2 MOI (multiplicity of infection) after 24 h of incubation at 37 °C in the presence of 5% CO2 were 20 ± 0.8 and 17 ± 0.7 μg mL?1 Met-BLG, respectively. Longer incubation period (4 days) was associated with low IC50% of the hemagglutination activity (7.1 ± 0.3 μg mL?1 Met-BLG) and low IC50% of immuno-fluorescence of viral nucleoproteins (9.7 ± 0.4 μg mL?1 Met-BLG) when using 0.2 and 0.1 MOI, respectively. A concentration of 25 μg mL?1 of Met-BLG reduced the amount of replicating virus by about 2 and 1.3 logs when the viral load was 0.01 and 0.1 MOI, respectively, while higher concentrations reduced it by about 5–6 logs. Antiviral action of Met-BLG was coupled with a cellular protective action, which reached 100% when using 0.01 and 0.1 MOI and 83% when using 1.0 MOI. The time of Met-BLG addition after the viral infection was determinant for its antiviral efficacy and for its protection of the infected MDCK cell lines. Anti-hemagglutination action and cell protective action decreased gradually and in parallel with the delay in the time of Met-BLG addition to disappear totally after 10 h delay. 相似文献