排序方式: 共有22条查询结果,搜索用时 15 毫秒
1.
Latefa Baba Ahme Sabrina Naam Aissa Keffous Abdelkader Hassein-Bey Toufik Hadjersi 《自然科学进展(英文版)》2015,25(2):101-110
It has been found that the silicon nanowires modified with noble metals can be used to fabricate an effective H2 gas sensor in the present study.The preparation and surface modification of silicon nanowires(Si NWs) were carried out by chemical methods. The morphology of the silicon nanowires unmodified and modified with nanoparticles of platinum, palladium, silver and gold was investigated using scanning electron microscopy(SEM). The chemical composition of the silicon nanowire layers was studied by secondary ion mass spectroscopy(SIMS) and energy dispersive X-ray analysis(EDX). The structures of type metal/Si NWs/p-Si/Al were fabricated. The electrical characterization(I–V) was performed in primary vacuum and H2 at different concentrations. It was found that the metal type used to modify the Si NWs strongly influenced the I–V characteristics. The response of these structures toward H2 gas was studied as a function of the metal type. Finally, the sensing characteristics and performance of the sensors were investigated. 相似文献
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Dyall SD Yan W Delgadillo-Correa MG Lunceford A Loo JA Clarke CF Johnson PJ 《Nature》2004,431(7012):1103-1107
Trichomonas vaginalis is a unicellular microaerophilic eukaryote that lacks mitochondria yet contains an alternative organelle, the hydrogenosome, involved in pyruvate metabolism. Pathways between the two organelles differ substantially: in hydrogenosomes, pyruvate oxidation is catalysed by pyruvate:ferredoxin oxidoreductase (PFOR), with electrons donated to an [Fe]-hydrogenase which produces hydrogen. ATP is generated exclusively by substrate-level phosphorylation in hydrogenosomes, as opposed to oxidative phosphorylation in mitochondria. PFOR and hydrogenase are found in eubacteria and amitochondriate eukaryotes, but not in typical mitochondria. Analyses of mitochondrial genomes indicate that mitochondria have a single endosymbiotic origin from an alpha-proteobacterial-type progenitor. The absence of a genome in trichomonad hydrogenosomes precludes such comparisons, leaving the endosymbiotic history of this organelle unclear. Although phylogenetic reconstructions of a few proteins indicate that trichomonad hydrogenosomes share a common origin with mitochondria, others do not. Here we describe a novel NADH dehydrogenase module of respiratory complex I that is coupled to the central hydrogenosomal fermentative pathway to form a hydrogenosomal oxidoreductase complex that seems to function independently of quinones. Phylogenetic analyses of hydrogenosomal complex I-like proteins Ndh51 and Ndh24 reveal that neither has a common origin with mitochondrial homologues. These studies argue against a vertical origin of trichomonad hydrogenosomes from the proto-mitochondrial endosymbiont. 相似文献
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Charlier C Coppieters W Rollin F Desmecht D Agerholm JS Cambisano N Carta E Dardano S Dive M Fasquelle C Frennet JC Hanset R Hubin X Jorgensen C Karim L Kent M Harvey K Pearce BR Simon P Tama N Nie H Vandeputte S Lien S Longeri M Fredholm M Harvey RJ Georges M 《Nature genetics》2008,40(4):449-454
The widespread use of elite sires by means of artificial insemination in livestock breeding leads to the frequent emergence of recessive genetic defects, which cause significant economic and animal welfare concerns. Here we show that the availability of genome-wide, high-density SNP panels, combined with the typical structure of livestock populations, markedly accelerates the positional identification of genes and mutations that cause inherited defects. We report the fine-scale mapping of five recessive disorders in cattle and the molecular basis for three of these: congenital muscular dystony (CMD) types 1 and 2 in Belgian Blue cattle and ichthyosis fetalis in Italian Chianina cattle. Identification of these causative mutations has an immediate translation into breeding practice, allowing marker assisted selection against the defects through avoidance of at-risk matings. 相似文献
4.
Pluchino S Zanotti L Rossi B Brambilla E Ottoboni L Salani G Martinello M Cattalini A Bergami A Furlan R Comi G Constantin G Martino G 《Nature》2005,436(7048):266-271
In degenerative disorders of the central nervous system (CNS), transplantation of neural multipotent (stem) precursor cells (NPCs) is aimed at replacing damaged neural cells. Here we show that in CNS inflammation, NPCs are able to promote neuroprotection by maintaining undifferentiated features and exerting unexpected immune-like functions. In a mouse model of chronic CNS inflammation, systemically injected adult syngeneic NPCs use constitutively activated integrins and functional chemokine receptors to selectively enter the inflamed CNS. These undifferentiated cells survive repeated episodes of CNS inflammation by accumulating within perivascular areas where reactive astrocytes, inflamed endothelial cells and encephalitogenic T cells produce neurogenic and gliogenic regulators. In perivascular CNS areas, surviving adult NPCs induce apoptosis of blood-borne CNS-infiltrating encephalitogenic T cells, thus protecting against chronic neural tissue loss as well as disease-related disability. These results indicate that undifferentiated adult NPCs have relevant therapeutic potential in chronic inflammatory CNS disorders because they display immune-like functions that promote long-lasting neuroprotection. 相似文献
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Corti S Salani S Del Bo R Torrente Y Strazzer S Belicchi M Paganoni S Li Z Comi GP Bresolin N Paulin D Scarlato G 《Cellular and molecular life sciences : CMLS》2001,58(1):135-140
The generation of human myogenic cell lines could potentially provide a valuable source for cell transplantation in myopathies. The dysregulation of proliferative-differentiative signals by viral oncogenes can result in the induction of apoptosis. Whether apoptosis occurred in myogenic cells expressing large T antigen (Tag) from SV40 upon differentiation was unknown. Human muscle satellite cells were transfected with two different constructs, containing either an origin-defective SV40 genome or Tag under vimentin promoter control. When differentiation was triggered, Tag expression reduced the formation of myotubes and dead cells showing apoptotic features were present. However, the cells expressing SV40 Tag under vimentin promoter control retained their capacity to form myotubes and expressed the myofibrillar proteins as myosin heavy chain and dystrophin when Tag expression was silent. Their apoptotic rate was similar to that of untransfected cells. The observation that apoptosis can be prevented by the down-regulation of Tag suggests that the programmed cell death induced in transformed cells can be reversed, and confirms the regulatory efficiency of the human vimentin promoter. 相似文献
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Autophagy in stem and progenitor cells 总被引:1,自引:1,他引:0
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Ferrante MI Zullo A Barra A Bimonte S Messaddeq N Studer M Dollé P Franco B 《Nature genetics》2006,38(1):112-117
The oral-facial-digital type I (OFD1) syndrome (OMIM 311200) is a human developmental disorder; affected individuals have craniofacial and digital abnormalities and, in 15% of cases, polycystic kidney. The disease is inherited as an X-linked dominant male-lethal trait. Using a Cre-loxP system, we generated knockout animals lacking Ofd1 and reproduced the main features of the disease, albeit with increased severity, possibly owing to differences of X inactivation patterns between human and mouse. We found failure of left-right axis specification in mutant male embryos, and ultrastructural analysis showed a lack of cilia in the embryonic node. Formation of cilia was defective in cystic kidneys from heterozygous females, implicating ciliogenesis as a mechanism underlying cyst development. In addition, we found impaired patterning of the neural tube and altered expression of the 5' Hoxa and Hoxd genes in the limb buds of mice lacking Ofd1, suggesting that Ofd1 could have a role beyond primary cilium organization and assembly. 相似文献
10.
O Rozenblatt-Rosen RC Deo M Padi G Adelmant MA Calderwood T Rolland M Grace A Dricot M Askenazi M Tavares SJ Pevzner F Abderazzaq D Byrdsong AR Carvunis AA Chen J Cheng M Correll M Duarte C Fan MC Feltkamp SB Ficarro R Franchi BK Garg N Gulbahce T Hao AM Holthaus R James A Korkhin L Litovchick JC Mar TR Pak S Rabello R Rubio Y Shen S Singh JM Spangle M Tasan S Wanamaker JT Webber J Roecklein-Canfield E Johannsen AL Barabási R Beroukhim E Kieff ME Cusick DE Hill K Münger JA Marto J Quackenbush 《Nature》2012,487(7408):491-495