排序方式: 共有38条查询结果,搜索用时 15 毫秒
1.
Kathleen Mahias Neveen Ahmed-El-Sayed Cyril Masante Juliette Bitard Cathy Staedel Fabien Darfeuille Michel Ventura Thérèse Astier-Gin 《Nucleic acids research》2010,38(12):4079-4091
The replication of the genomic RNA of the hepatitis C virus (HCV) of positive polarity involves the synthesis of a replication intermediate of negative polarity by the viral RNA-dependent RNA polymerase (NS5B). In vitro and likely in vivo, the NS5B initiates RNA synthesis without primers. This de novo mechanism needs specific interactions between the polymerase and viral RNA elements. Cis-acting elements involved in the initiation of (–) RNA synthesis have been identified in the 3′ non-coding region and in the NS5B coding region of the HCV RNA. However, the detailed contribution of sequences and/or structures of (–) RNA involved in the initiation of (+) RNA synthesis has been less studied. In this report, we identified an RNA element localized between nucleotides 177 and 222 from the 3′-end of the (–) RNA that is necessary for efficient initiation of RNA synthesis by the recombinant NS5B. By site-directed mutagenesis experiments, we demonstrate that the structure rather than the primary sequence of this domain is important for RNA synthesis. We also demonstrate that the intact structure of this RNA element is also needed for efficient RNA synthesis when the viral NS5B functions in association with other viral and cellular proteins in cultured hepatic cells. 相似文献
2.
Déborah Harrus Neveen Ahmed-El-Sayed Philip C. Simister Steve Miller Martine Triconnet Curt H. Hagedorn Kathleen Mahias Félix A. Rey Thérèse Astier-Gin Stéphane Bressanelli 《The Journal of biological chemistry》2010,285(43):32906-32918
The hepatitis C virus (HCV) NS5b protein is an RNA-dependent RNA polymerase
essential for replication of the viral RNA genome. In vitro and
presumably in vivo, NS5b initiates RNA synthesis by a
de novo mechanism. Different structural elements of NS5b
have been reported to participate in RNA synthesis, especially a so-called
“β-flap” and a C-terminal segment (designated
“linker”) that connects the catalytic core of NS5b to a
transmembrane anchor. High concentrations of GTP have also been shown to
stimulate de novo RNA synthesis by HCV NS5b. Here we describe a
combined structural and functional analysis of genotype 1 HCV-NS5b of strains
H77 (subtype 1a), for which no structure has been previously reported, and J4
(subtype 1b). Our results highlight the linker as directly involved in lifting
the first boundary to processive RNA synthesis, the formation of the first
dinucleotide primer. The transition from this first dinucleotide primer state to
processive RNA synthesis requires removal of the linker and of the
β-flap with which it is shown to strongly interact in crystal
structures of HCV NS5b. We find that GTP specifically stimulates this transition
irrespective of its incorporation in neosynthesized RNA. 相似文献
3.
Ahmed Mostafa Soliman Neveen Samy Gadallah Hathal Mohammed Al Dhafer 《Zoology in the Middle East.》2017,63(1):58-62
In the present study, the genus Gynecaptera Skorikov, 1935 is recorded from the Arabian Peninsula for the first time, with a nocturnal new species, G. arabica Soliman &; Gadallah, which has been collected from the Riyadh region in Saudi Arabia and which is described and illustrated.http://www.zoobank.org/urn:lsid:zoobank.org:pub:F7ACB779-3750-4DC6-B29B-B7F290E7C7B4 相似文献
4.
The morphology of the antennal sensilla of both male and female Habrobracon hebetor (Say) (Hymenoptera: Braconidae) is described using Scanning Electron Microscopy complemented with Transmission Electron Microscopy.
Five types of innervated sensilla as well as uninnervated microtrichia were found. These types are: sensilla trichodea; s.
chaetica; s. basiconica; s. coeloconica; and s. placodea. No differences in shape, basic structure, and types of antennal
sensilla were found between males and females. The types of sensilla of both sexes of H. hebetor were compared with what has been described in other parasitic Hymenoptera, and their putative functions are discussed with
reference to their morphology, distribution and ultrastructure. 相似文献
5.
Neveen S. Geweely Hala A. M. Afifi Shehata A. Abdelrahim Saleha Y. M. Alakilli 《Geomicrobiology journal》2014,31(6):529-539
An archeological wooden painted coffin was excavated in Tety tomb from Saqqara excavation. It belonged to the Ministry of Antiquities. This coffin was discovered in a bad state of conservation with many destroyed big and small pieces in Saqqara stores. Analyses and investigation study were performed on the ground layer of the coffin by X-ray diffraction (XRD), Energy dispersive X ray analysis (EDX) equipped with environmental scanning electron microscopy (ESEM) and Fourier transform infrared spectroscopy (FTIR). Results confirmed that the degradation factors affecting the wooden painted coffin are essentially attributed to direct effects of microbial phenomena, which have lead to many deterioration forms as: macro- and microcracks, hydrated salts, flaking, coloration, scaling and defoliation microbiological spots. Nine deteriorating fungal species were isolated from the painted and ground layers of the tested coffin. Fusarium moniliforme followed by Aspergillus flavus able to significantly solublize calcium salts as major components of the ground layer of archeological wooden coffin. Effect of ozone and Gamma sterilization on growth; lipid, tryptophan oxidation and protein, nucleic acid leakage in the most dominant toxigenic deteriorated fungal species were detected. No mycelial growth was observed at 4 ppm of ozone at all exposure times. As Gamma radiation dose increased over 250 Gy, the growth parameter gradually decreased to reach the lethal dose at 2000 Gy. The production of mycotoxins by the tested toxigenic fungi was completely disappeared under the exposure to 3 ppm and 90 min to ozone. 相似文献
6.
Daw-Yang Hwang Stefan Kohl Xueping Fan Asaf Vivante Stefanie Chan Gabriel C. Dworschak Julian Schulz Albertien M. van Eerde Alina C. Hilger Heon Yung Gee Tracie Pennimpede Bernhard G. Herrmann Glenn van de Hoek Kirsten Y. Renkema Christoph Schell Tobias B. Huber Heiko M. Reutter Neveen A. Soliman Natasa Stajic Radovan Bogdanovic Elijah O. Kehinde Richard P. Lifton Velibor Tasic Weining Lu Friedhelm Hildebrandt 《Human genetics》2015,134(8):905-916
7.
Rania A. A. Salama Rania M. Abdelsalam O. M. E. Abdel‐Salam Mahmoud M. khattab Neveen A. Salem Zakaria A. El‐Khyat Fatma A. Morsy Ezz‐El Din S. Eldenshary 《Journal of biochemical and molecular toxicology》2019,33(3)
The current study aimed to evaluate the role of cannabinoid receptors in the regulation of gastric acid secretion and oxidative stress in gastric mucosa. To fulfill this aim, gastric acid secretion stimulated with histamine (5 mg/kg, subcutaneous [SC]), 2‐deoxy‐ d ‐glucose (D‐G) (200 mg/kg, intravenous) or ‐carbachol (4 μg/kg, SC) in the 4‐hour pylorus‐ligated rats. The CB1R agonist ( N‐arachidonoyl dopamine, 1 mg/kg, SC) inhibited gastric acid secretion stimulated by D‐G and carbachol but not in histamine, reduced pepsin content, and increased mucin secretion. Furthermore, it decreased malondialdehyde (MDA) and nitric oxide (NO) contents with an increase in glutathione (GSH) and paraoxonase 1 (PON‐1). Meanwhile, CB2R antagonist (AM630, 1 mg/kg, SC) inhibited gastric acid secretion stimulated by D‐G and reduced MDA and NO contents with an increase in GSH and PON‐1. Meanwhile, CB1R antagonist rimonabant or CB2R agonist GW 405833 had no effect on stimulated gastric acid secretion. Therefore, both CB1R agonist and CB2R antagonist may exert antisecretory and antioxidant potential in the stomach. 相似文献
8.
Cao Z Said N Amin S Wu HK Bruce A Garate M Hsu DK Kuwabara I Liu FT Panjwani N 《The Journal of biological chemistry》2002,277(44):42299-42305
Disorders of wound healing characterized by impaired or delayed re-epithelialization are a serious medical problem. These conditions affect many tissues, are painful, and are difficult to treat. In this study, using cornea as a model, we demonstrate for the first time the importance of carbohydrate-binding proteins galectins-3 and -7 in re-epithelialization of wounds. In two different models of corneal wound healing, re-epithelialization of wounds was significantly slower in galectin-3-deficient (gal3(-/-)) mice compared with wild-type (gal3(+/+)) mice. In contrast, there was no difference in corneal epithelial wound closure rates between galectin-1-deficient and wild-type mice. Quantitation of the bromodeoxyuridine-labeled cells in gal3(+/+) and gal3(-/-) corneas revealed that corneal epithelial cell proliferation rate is not perturbed in gal3(-/-) corneas. Exogenous galectin-3 accelerated re-epithelialization of wounds in gal3(+/+) mice but, surprisingly, not in the gal3(-/-) mice. Gene expression analysis using cDNA microarrays revealed that healing corneas of gal3(-/-) mice contain markedly reduced levels of galectin-7 compared with those of gal3(+/+) mice. More importantly, unlike galectin-3, galectin-7 accelerated re-epithelialization of wounds in both gal3(-/-) and gal3(+/+) mice. In corresponding experiments, recombinant galectin-1 did not stimulate the corneal epithelial wound closure rate. The extent of acceleration of re-epithelialization of wounds with both galectin-3 and galectin-7 was greater than that observed in most of the published studies using growth factors. These findings have broad implications for developing novel therapeutic strategies for treating nonhealing wounds. 相似文献
9.
Oxidative stress has been implicated to play a role in epileptogenesis and pilocarpine-induced seizures. The present study
aims to evaluate the antioxidant effects of curcumin, Nigella sativa oil (NSO) and valproate on the levels of malondialdehyde, nitric oxide, reduced glutathione and the activities of catalase,
Na+, K+-ATPase and acetylcholinesterase in the hippocampus of pilocarpine-treated rats. The animal model of epilepsy was induced
by pilocarpine and left for 22 days to establish the chronic phase of epilepsy. These animals were then treated with curcumin,
NSO or valproate for 21 days. The data revealed evidence of oxidative stress in the hippocampus of pilocarpinized rats as
indicated by the increased nitric oxide levels and the decreased glutathione levels and catalase activity. Moreover, a decrease
in Na+, K+-ATPase activity and an increase in acetylcholinesterase activity occurred in the hippocampus after pilocarpine. Treatment
with curcumin, NSO or valproate ameliorated most of the changes induced by pilocarpine and restored Na+, K+-ATPase activity in the hippocampus to control levels. This study reflects the promising anticonvulsant and potent antioxidant
effects of curcumin and NSO in reducing oxidative stress, excitability and the induction of seizures in epileptic animals
and improving some of the adverse effects of antiepileptic drugs. 相似文献
10.
This study aimed to isolate quercetin (for the first time) from Anabaena aequalis Borge, which inhabits soil surface of Wadi El‐Alaqui Protectorate located in Aswan city, Egypt. The isolated compound showed significant antibacterial activity against the gram‐positive bacteria Sarcina maxima and Micrococcus kristinae, the gram‐negative bacterium Klebsiella pneumoniae, as well as against the filamentous fungus Aspergillus flavus. The isolated compound was identified as quercetin using the structure elucidation based on UV, electrospray ionization mass spectrometry (ESIMS), 1H and 13C NMR, proton–proton correlation spectroscopy (1H‐1H COSY), distortionless enhancement by polarization transfer (DEPT), heteronuclear single quantum coherence (HSQC), and heteronuclear multiple bond correlations spectrum (HMBC). Medium lethal dose (LD50) of the isolated compound and its side effects against hyperlipidemia induced by ethanol intake in albino rats were carried out. No deaths were reported in rats within 72 h, which suggests that the isolated compound plays a beneficial role as an antihyperlipidemic agent in the treatment of alcohol‐induced hepatic tissue damage, which can be described as one of the therapeutic values. 相似文献