排序方式: 共有44条查询结果,搜索用时 31 毫秒
31.
Transgenic expression and activation of PGC-1α protect dopaminergic neurons in the MPTP mouse model of Parkinson’s disease 总被引:1,自引:1,他引:0
32.
Evidence for complete denitrification in a benthic foraminifer 总被引:2,自引:0,他引:2
Risgaard-Petersen N Langezaal AM Ingvardsen S Schmid MC Jetten MS Op den Camp HJ Derksen JW Piña-Ochoa E Eriksson SP Nielsen LP Revsbech NP Cedhagen T van der Zwaan GJ 《Nature》2006,443(7107):93-96
Benthic foraminifera are unicellular eukaryotes found abundantly in many types of marine sediments. Many species survive and possibly reproduce in anoxic habitats, but sustainable anaerobic metabolism has not been previously described. Here we demonstrate that the foraminifer Globobulimina pseudospinescens accumulates intracellular nitrate stores and that these can be respired to dinitrogen gas. The amounts of nitrate detected are estimated to be sufficient to support respiration for over a month. In a Swedish fjord sediment where G. pseudospinescens is the dominant foraminifer, the intracellular nitrate pool in this species accounted for 20% of the large, cell-bound, nitrate pool present in an oxygen-free zone. Similarly high nitrate concentrations were also detected in foraminifera Nonionella cf. stella and a Stainforthia species, the two dominant benthic taxa occurring within the oxygen minimum zone of the continental shelf off Chile. Given the high abundance of foraminifera in anoxic marine environments, these new findings suggest that foraminifera may play an important role in global nitrogen cycling and indicate that our understanding of the complexity of the marine nitrogen cycle is far from complete. 相似文献
33.
Cytoskeletal filaments of heart conducting system localized by antibody against a 55,000 dalton protein. 总被引:1,自引:0,他引:1
Cow heart conducting cells characteristically contain cytoplasmic intermediate-sized filaments. We report here the preparation of a specific antibody to a 55,000 dalton protein of isolated cow Purkinje fibres. Confirmation has been obtained that these filaments consist of the 55,000 dalton protein, using the indirect immunofluorescence technique. Cross-reaction is seen with vascular endothelium and smooth muscle cells of various origin, suggesting close identity of different types of intermediate-sized filaments. 相似文献
34.
The hydrophobic cores of proteins are generally well packed, with few cavities. Mutations in which a bulky buried residue such as leucine or phenylalanine is replaced with a small residue such as alanine can create cavities in the core of a protein (our unpublished results). The sizes and shapes of such cavities can vary substantially depending on factors such as local geometry, whether or not a cavity already exists at the site of substitution, and the degree to which the protein structure relaxes to occupy the space vacated by the substituted residue. We show by crystallographic and thermodynamic analysis that the cavity created by the replacement Leu 99----Ala in T4 lysozyme is large enough to bind benzene and that ligand binding increases the melting temperature of the protein by 6.0 degrees C at pH 3.0. Benzene does not, however, bind to the cavity created by the Phe 153----Ala replacement. The results show that cavities can be engineered in proteins and suggest that such cavities might be tailored to bind specific ligands. The binding of benzene at an internal site 7 A from the molecular surface also illustrates the dynamic nature of proteins, even in crystals. 相似文献
35.
Shafqat N Shafqat J Eissner G Marschall HU Tryggvason K Eriksson U Gabrielli F Lardy H Jörnvall H Oppermann U 《Cellular and molecular life sciences : CMLS》2006,63(10):1205-1213
Human Hep27 was originally isolated from growth-arrested HepG2 cells and identified as a member of the superfamily of short-chain
dehydrogenases/reductases (SDR). Its substrate specificity has not been determined, but a cross-species comparison suggests
that it occurs in widely divergent species, such as human, Cenorhabditis elegans, Drosophila and Arabidopsis thaliana. In this study, Hep27 was expressed as a His6 fusion protein, and subjected to a substrate screen, using a compound library of SDR substrates, comprising steroids, retinoids,
sugars and carbonyl compounds. Whereas no steroid dehydrogenase or retinoid activity was detected, it was found that Hep27
catalyzed the NADPH-dependent reduction of dicarbonyl compounds, like 3,4-hexanedione and 1-phenyl-1,2-propanedione with similar
turnover numbers as DCXR (a mitochondrial dicarbonyl reductase/xylulose reductase). In contrast, Hep27 does not convert sugar
substrates like xylulose or threose. Based on its substrate specificity and expression in endothelial tissues, it is suggested
that Hep27 functions as a dicarbonyl reductase in enzymatic inactivation of reactive carbonyls, involved in covalent modification
of cellular components.
Received 16 January 2006; received after revision 28 February 2006; accepted 31 March 2006 相似文献
36.
Estrada K Styrkarsdottir U Evangelou E Hsu YH Duncan EL Ntzani EE Oei L Albagha OM Amin N Kemp JP Koller DL Li G Liu CT Minster RL Moayyeri A Vandenput L Willner D Xiao SM Yerges-Armstrong LM Zheng HF Alonso N Eriksson J Kammerer CM Kaptoge SK Leo PJ Thorleifsson G Wilson SG Wilson JF Aalto V Alen M Aragaki AK Aspelund T Center JR Dailiana Z Duggan DJ Garcia M Garcia-Giralt N Giroux S Hallmans G Hocking LJ Husted LB Jameson KA Khusainova R Kim GS Kooperberg C Koromila T Kruk M Laaksonen M 《Nature genetics》2012,44(5):491-501
Bone mineral density (BMD) is the most widely used predictor of fracture risk. We performed the largest meta-analysis to date on lumbar spine and femoral neck BMD, including 17 genome-wide association studies and 32,961 individuals of European and east Asian ancestry. We tested the top BMD-associated markers for replication in 50,933 independent subjects and for association with risk of low-trauma fracture in 31,016 individuals with a history of fracture (cases) and 102,444 controls. We identified 56 loci (32 new) associated with BMD at genome-wide significance (P < 5 × 10(-8)). Several of these factors cluster within the RANK-RANKL-OPG, mesenchymal stem cell differentiation, endochondral ossification and Wnt signaling pathways. However, we also discovered loci that were localized to genes not known to have a role in bone biology. Fourteen BMD-associated loci were also associated with fracture risk (P < 5 × 10(-4), Bonferroni corrected), of which six reached P < 5 × 10(-8), including at 18p11.21 (FAM210A), 7q21.3 (SLC25A13), 11q13.2 (LRP5), 4q22.1 (MEPE), 2p16.2 (SPTBN1) and 10q21.1 (DKK1). These findings shed light on the genetic architecture and pathophysiological mechanisms underlying BMD variation and fracture susceptibility. 相似文献
37.
Lindström S Vachon CM Li J Varghese J Thompson D Warren R Brown J Leyland J Audley T Wareham NJ Loos RJ Paterson AD Rommens J Waggott D Martin LJ Scott CG Pankratz VS Hankinson SE Hazra A Hunter DJ Hopper JL Southey MC Chanock SJ Silva Idos S Liu J Eriksson L Couch FJ Stone J Apicella C Czene K Kraft P Hall P Easton DF Boyd NF Tamimi RM 《Nature genetics》2011,43(3):185-187
High-percent mammographic density adjusted for age and body mass index is one of the strongest risk factors for breast cancer. We conducted a meta analysis of five genome-wide association studies of percent mammographic density and report an association with rs10995190 in ZNF365 (combined P = 9.6 × 10(-10)). Common variants in ZNF365 have also recently been associated with susceptibility to breast cancer. 相似文献
38.
Electrical properties of wet collagen 总被引:10,自引:0,他引:10
39.
N. E. Eriksson N. V. B. Marsden D. Z. Popov 《Cellular and molecular life sciences : CMLS》1974,30(5):572-574
Zusammenfassung In gefriergetrockneten Schnitten von Sephadex G-25 wurde die Verteilung einiger Alkalihalogenverbindungen mit Hilfe ihrer Röntgenstrahlenfluoreszenz im Raster-Elektronenmikroskop untersucht. Es ergab sich eine ionisch homogene radiale Verteilung und fluoreszierende Makromoleküle (Dextran) wurden von den Gelschichten ausgeschieden.
We wish to thank Pharmacia, Uppsala, for very kindly giving the fluorescent dextran and Sephadex® G-25. We also want to thank DrL. O. Lindbom for informative discussions and acknowledge financial support from the Swedish Natural Science Research Council, Grant No 2944. 相似文献
We wish to thank Pharmacia, Uppsala, for very kindly giving the fluorescent dextran and Sephadex® G-25. We also want to thank DrL. O. Lindbom for informative discussions and acknowledge financial support from the Swedish Natural Science Research Council, Grant No 2944. 相似文献
40.
Andresen GB Ashkezari MD Baquero-Ruiz M Bertsche W Bowe PD Butler E Cesar CL Chapman S Charlton M Deller A Eriksson S Fajans J Friesen T Fujiwara MC Gill DR Gutierrez A Hangst JS Hardy WN Hayden ME Humphries AJ Hydomako R Jenkins MJ Jonsell S Jørgensen LV Kurchaninov L Madsen N Menary S Nolan P Olchanski K Olin A Povilus A Pusa P Robicheaux F Sarid E el Nasr SS Silveira DM So C Storey JW Thompson RI van der Werf DP Wurtele JS Yamazaki Y 《Nature》2010,468(7324):673-676
Antimatter was first predicted in 1931, by Dirac. Work with high-energy antiparticles is now commonplace, and anti-electrons are used regularly in the medical technique of positron emission tomography scanning. Antihydrogen, the bound state of an antiproton and a positron, has been produced at low energies at CERN (the European Organization for Nuclear Research) since 2002. Antihydrogen is of interest for use in a precision test of nature's fundamental symmetries. The charge conjugation/parity/time reversal (CPT) theorem, a crucial part of the foundation of the standard model of elementary particles and interactions, demands that hydrogen and antihydrogen have the same spectrum. Given the current experimental precision of measurements on the hydrogen atom (about two parts in 10(14) for the frequency of the 1s-to-2s transition), subjecting antihydrogen to rigorous spectroscopic examination would constitute a compelling, model-independent test of CPT. Antihydrogen could also be used to study the gravitational behaviour of antimatter. However, so far experiments have produced antihydrogen that is not confined, precluding detailed study of its structure. Here we demonstrate trapping of antihydrogen atoms. From the interaction of about 10(7) antiprotons and 7?×?10(8) positrons, we observed 38 annihilation events consistent with the controlled release of trapped antihydrogen from our magnetic trap; the measured background is 1.4?±?1.4 events. This result opens the door to precision measurements on anti-atoms, which can soon be subjected to the same techniques as developed for hydrogen. 相似文献