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51.
Biomarkers aid the study of osteoarthritis (OA) in a number of different ways. In this article we summarise briefly their
multiple uses and reflect on how the study reported in a previous edition of Arthritis Research & Therapy should promote further investigation of cartilage oligomeric matrix protein (COMP). COMP is foremost among hitherto investigated
biomarkers and is most consistently shown to predict knee OA progression. Precisely what role it plays in OA pathogenesis
remains unclear and elucidating this may be key to defining, and then targeting, the cellular pathways involved in OA. 相似文献
52.
Kyaw Tha Paw U Matthias Falk Thomas H. Suchanek Susan L. Ustin Jiquan Chen Young-San Park William E. Winner Sean C. Thomas Theodore C. Hsiao Roger H. Shaw Thomas S. King R. David Pyles Matt Schroeder Anthony A. Matista 《Ecosystems》2004,7(5):513-524
Eddy-covariance and biometeorological methods show significant net annual carbon uptake in an old-growth Douglas-fir forest in southwestern Washington, USA. These results contrast with previous assumptions that old-growth forest ecosystems are in carbon equilibrium. The basis for differences between conventional biomass-based carbon sequestration estimates and the biometeorologic estimates are discussed. Annual net ecosystem exchange was comparable to younger ecosystems at the same latitude, as quantified in the AmeriFlux program. Net ecosystem carbon uptake was significantly correlated with photosynthetically active radiation and air temperature, as well as soil moisture and precipitation. Optimum ecosystem photosynthesis occurred at relatively cool temperatures (5°–10°C). Understory and soil carbon exchange always represented a source of carbon to the atmosphere, with a strong seasonal cycle in source strength. Understory and soil carbon exchange showed a Q10 temperature dependence and represented a substantial portion of the ecosystem carbon budget. The period of main carbon uptake and the period of soil and ecosystem respiration are out of phase, however, and driven by different climatic boundary conditions. The period of strongest ecosystem carbon uptake coincides with the lowest observed values of soil and ecosystem respiration. Despite the substantial contribution of soil, the overall strength of the photosynthetic sink resulted in the net annual uptake. The net uptake estimates here included two correction methods, one for advection and the other for low levels of turbulence. 相似文献
53.
Khajeddin SJ Akbari M Karimzadeh HR Eghbal MK 《植物生态学报》2008,32(2):328-335
Aims Desertification results in ecological and biological diminution of the earth, and can happen naturally or cause by anthropogenic activities. This process especially affects arid and semi-arid regions, such as the Isfahan region, where the spread of desertification is reaching critical proportions. The aim of this study is to use remotely sensed data to review the trend of desertification in the northern of Isfahan, Iran. Methods Multi-temporal images were employed to evaluate the trend of desertification, specifically the TM and ETM+ data of September, 1990 and September, 2001. Geometric and radiometric corrections were applied to each image prior to image processing and supervised classification, and vegetation indices were applied to produce a land use map of each image in nine classes. The land use classification s in the two map images were compared and changes between land use classes were detected over the 11 year period using a fuzzy and post-classification technique. Important findings The maps and their comparison with false color composite images showed the differences efficiently. With the fuzzy and post-classification method the land use changes were sited on the map. Fuzzy confirmed 53% changed area and 47% unchanged areas in the study region. The results verify the desertification expansion in the study areas. Because of poor land management, agricultural lands converted to desert and abandoned areas, and some marginal pasture lands had to be changed to agricultural land which are desertification spreading according to United Nations Conference on Desertification (UNCOD). Also farmland and pastures have been converted to urban and industrial areas, and the rangelands have been spoiled due to opencast mine excavations. With the mine margins eroding as well as their debris accumulating on the pasture lands, desertification has become worse. Three areas of less-elevated mountains have remained unchanged. This study confirmed that the anthropogenic activities accelerated the desertification process and severely endangered the remaining areas. 相似文献
54.
Background
There are two different theories about the development of the genetic code. Woese suggested that it was developed in connection with the amino acid repertoire, while Crick argued that any connection between codons and amino acids is only the result of an "accident". This question is fundamental to understand the nature of specific protein-nucleic acid interactions. 相似文献55.
56.
Binding to serine 65‐phosphorylated ubiquitin primes Parkin for optimal PINK1‐dependent phosphorylation and activation 下载免费PDF全文
Agne Kazlauskaite R Julio Martínez‐Torres Scott Wilkie Atul Kumar Julien Peltier Alba Gonzalez Clare Johnson Jinwei Zhang Anthony G Hope Mark Peggie Matthias Trost Daan MF van Aalten Dario R Alessi Alan R Prescott Axel Knebel Helen Walden Miratul MK Muqit 《EMBO reports》2015,16(8):939-954
Mutations in the mitochondrial protein kinase PINK1 are associated with autosomal recessive Parkinson disease (PD). We and other groups have reported that PINK1 activates Parkin E3 ligase activity both directly via phosphorylation of Parkin serine 65 (Ser65)—which lies within its ubiquitin‐like domain (Ubl)—and indirectly through phosphorylation of ubiquitin at Ser65. How Ser65‐phosphorylated ubiquitin (ubiquitinPhospho‐Ser65) contributes to Parkin activation is currently unknown. Here, we demonstrate that ubiquitinPhospho‐Ser65 binding to Parkin dramatically increases the rate and stoichiometry of Parkin phosphorylation at Ser65 by PINK1 in vitro. Analysis of the Parkin structure, corroborated by site‐directed mutagenesis, shows that the conserved His302 and Lys151 residues play a critical role in binding of ubiquitinPhospho‐Ser65, thereby promoting Parkin Ser65 phosphorylation and activation of its E3 ligase activity in vitro. Mutation of His302 markedly inhibits Parkin Ser65 phosphorylation at the mitochondria, which is associated with a marked reduction in its E3 ligase activity following mitochondrial depolarisation. We show that the binding of ubiquitinPhospho‐Ser65 to Parkin disrupts the interaction between the Ubl domain and C‐terminal region, thereby increasing the accessibility of Parkin Ser65. Finally, purified Parkin maximally phosphorylated at Ser65 in vitro cannot be further activated by the addition of ubiquitinPhospho‐Ser65. Our results thus suggest that a major role of ubiquitinPhospho‐Ser65 is to promote PINK1‐mediated phosphorylation of Parkin at Ser65, leading to maximal activation of Parkin E3 ligase activity. His302 and Lys151 are likely to line a phospho‐Ser65‐binding pocket on the surface of Parkin that is critical for the ubiquitinPhospho‐Ser65 interaction. This study provides new mechanistic insights into Parkin activation by ubiquitinPhospho‐Ser65, which could aid in the development of Parkin activators that mimic the effect of ubiquitinPhospho‐Ser65. 相似文献
57.
Méndez-Andino JL Colson AO Meyers KM Mitchell MC Hodge K Howard JM Kim N Ackley DC Holbert JK Mittelstadt SW Dowty ME Obringer CM Suchanek P Reizes O Hu XE Wos JA 《Bioorganic & medicinal chemistry》2007,15(5):2092-2105
The design, synthesis, and biological studies of a novel class of MCH-R1 antagonists based on an aminotetrahydronaphthalene ketopiperazine scaffold is described. Compounds within this class promoted significant body weight reduction in mouse diet induced obesity studies. The potential for hERG blockage activity and QT interval studies in anesthetized dogs are discussed. 相似文献
58.
在韩国境内Potentilla fragarioides var.sprengeliana的遗传多样 … 总被引:1,自引:0,他引:1
根据22个等位酶位点遗传变异,探讨了韩国境内委陵菜(Potentilla fragarioides L.var.sprengeliana)的遗传多样性和种群结构。酶位点的多态位点百分比为59.1%。种和种群水平上的遗传多样性比较高,分别为Hes=0.210,Hep=0.199;而种群的分化水平则相对较低(GST=0.074)。19个种群中随机交配的偏差为FIS=0.331。每代迁移数的间接估计 相似文献
59.
Verena Maria Suchanek María Esteban-López Rémy Colin Olga Besharova Kirstin Fritz Victor Sourjik 《Molecular microbiology》2020,113(4):728-739
Attachment to surfaces is an important early step during bacterial infection and during formation of submerged biofilms. Although flagella-mediated motility is known to be important for attachment of Escherichia coli and other bacteria, implications of motility regulation by cellular signalling remain to be understood. Here, we show that motility largely promotes attachment of E. coli, including that mediated by type 1 fimbriae, by allowing cells to reach, get hydrodynamically trapped at and explore the surface. Inactivation or inhibition of the chemotaxis signalling pathway improves attachment by suppressing cell reorientations and thereby increasing surface residence times. The attachment is further enhanced by deletion of genes encoding the cyclic diguanosine monophosphate (c-di-GMP)-dependent flagellar brake YcgR or the diguanylate cyclase DgcE. Such increased attachment in absence of c-di-GMP signalling is in contrast to its commonly accepted function as a positive regulator of the sessile state. It is apparently due to the increased swimming speed of E. coli in absence of YcgR-mediated motor control, which strengthens adhesion mediated by the type 1 fimbriae. Thus, both signalling networks that regulate motility of E. coli also control its engagement with both biotic and abiotic surfaces, which has likely implications for infection and biofilm formation. 相似文献
60.