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51.
A broad range of herbaceous plant comunities in a Mediterranean Landscape in central Italy, running from heavily urbanized
areas to semi-natural pastures, has been studied. These communities can be easily arranged along a gradient of ruderality.
We inspected which of a series of soil parameters could better explain this gradient (pH, CaCO3, granulometry, N, P, C/N, P/N). We show that (1) the single most important explanatory variable is P/N ratio of soil; (2)
nitrogen and carbon pools in soil are related, in the set of communities studied, with another gradient of decreasingly frequent,
predictable, moderate disturbance such as trampling. We discuss the meaning of these results.
Nomenclature: Anzalone (1994, 1996). 相似文献
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Kauko A Haataja S Pulliainen AT Finne J Papageorgiou AC 《Journal of molecular biology》2004,338(3):547-558
The Dps-like peroxide resistance protein (Dpr) is an aerotolerance and hydrogen peroxide resistance agent found in the meningitis-associated pathogen Streptococcus suis. Dpr is believed to act by binding free intracellular iron to prevent Fenton chemistry-catalysed formation of toxic hydroxyl radicals. The crystal structure of Dpr has been determined to 1.95 A resolution. The final model has an Rcyst value of 18.5% (Rfree = 22.4%) and consists of 12 identical monomers (each of them comprising a four alpha-helix bundle) that form a hollow sphere obeying 23 symmetry. Structural features show that Dpr belongs to the Dps family of bacterial proteins. Twelve putative ferroxidase centers, each formed at the interface of neighboring monomer pairs, were identified in the Dpr structure with structural similarities to those found in other Dps family members. Dpr was crystallized in the absence of iron, hence no bound iron was found in the structure in contrast to other Dps family members. A novel metal-binding site approximately 6A from the ferroxidase centre was identified and assigned to a bound calcium ion. Two residues from the ferroxidase centre (Asp63 and Asp74) were found to be involved in calcium binding. Structural comparison with other family members revealed that Asp63 and Asp74 adopt different conformation in the Dpr structure. The structure of Dpr presented here shows potential local conformational changes that may occur during iron incorporation. A role for the metal-binding site in iron uptake is proposed. 相似文献
53.
G. Gaibelet C. Millot C. Lebrun S. Ravault A. Saulière A. André 《Molecular membrane biology》2013,30(5):423-435
Cholesterol in the plasma membrane of eukaryotic cells contributes to modulating the functions and signalling pathways of numerous transmembrane proteins, including G protein Coupled Receptors (GPCRs). We have previously shown that the function of the human µ-opioid receptor (hMOR) expressed in Saccharomyces cerevisiae is modulated by sterols including cholesterol. Here, we investigated the effects of cholesterol content on hMOR pharmacology and on hMOR partitioning in cholesterol-poor and -rich domains in eukaryotic mammalian cells (CHO). We show that cholesterol is required for the stabilization of a receptor conformation with high agonist affinity and for triggering G-protein activation after agonist binding to the receptor. Biochemical analysis of untreated and cholesterol-depleted membranes in cells expressing hMOR indicated that the receptor is only present in cholesterol poor domains, in the basal state. After agonist binding to untreated CHO membranes, two distinct populations of receptor were found in cholesterol-rich and -poor domains. Cholesterol depletion or treatment of CHO membranes with the G-protein-decoupling agent GppNHp prevented the redistribution, indicating that receptor activated states localized into cholesterol-rich domains. Pharmacological data and biochemical analysis indicate that distinct activated conformations of hMOR exist in CHO plasma membrane and correspond to microdomains differing by thickness and proportions of lipid components, including cholesterol. 相似文献
54.
The contemporary genetic pattern of European moose is shaped by postglacial recolonization,bottlenecks, and the geographical barrier of the Baltic Sea 下载免费PDF全文
Magdalena Niedziałkowska Kris J. Hundertmark Bogumiła Jędrzejewska Vadim E. Sidorovich Hanna Zalewska Rauno Veeroja Erling J. Solberg Sauli Laaksonen Håkan Sand Vyacheslav A. Solovyev Andrey Sagaydak Juha Tiainen Rimvydas Juškaitis Gundega Done Vadim A. Borodulin Evgenii A. Tulandin Krzysztof Niedziałkowski 《Biological journal of the Linnean Society. Linnean Society of London》2016,117(4):879-894
To investigate genetic diversity and the population structure of the European moose (Alces alces), we analyzed 14 microsatellite loci for 694 samples collected across 16 localities. The highest genetic diversity was detected in Belarus and Russia and the lowest was found in Scandinavia. Two major genetic clusters existed, Scandinavian and continental, and some further spatial structure was detected. There was high concordance between the spatial distribution of microsatellite clusters analyzed in the present study and previously recognized mitochondrial DNA clades of moose. The split of genetic lineages calculated using approximate Bayesian computation (ABC) occurred at the beginning of the Last Glacial Maximum: approximately 29 000 and 28 000 years BP. A range‐wide bottleneck detected by ABC took place 1800–1200 years BP, although a more recent decline in moose numbers was also documented in the 18th to early 20th Century. Genetic differentiation in European moose increased with geographical distance, and the Baltic Sea appeared to be a barrier to gene flow. We conclude that isolation in different glacial refugia, postglacial colonization, and declines of range and numbers in Holocene shaped the present pattern of genetic diversity of European moose. Based on genetic divergence and a lack of apparent gene flow, the contemporary Scandinavian and continental subpopulations should be treated as separate management units. 相似文献
55.
Magdalena Niedziałkowska Kris J. Hundertmark Bogumiła Jędrzejewska Krzysztof Niedziałkowski Vadim E. Sidorovich Marcin Górny Rauno Veeroja Erling J. Solberg Sauli Laaksonen Håkan Sand Vyacheslav A. Solovyev Maryna Shkvyria Juha Tiainen Innokentiy M. Okhlopkov Rimvydas Juškaitis Gundega Done Vadim A. Borodulin Evgenii A. Tulandin Włodzimierz Jędrzejewski 《Journal of Biogeography》2014,41(11):2173-2184
56.
Several new ortho-alkyl and heteroalkyl substituted aryl and aryl alkyl phosphanes and their palladium complexes have been selectively prepared, characterized and compared as potential catalysts for the Suzuki coupling reaction. The modification of the structures of the palladium complexes were made in search of the best possible catalytic activity. The novel catalysts were subsequently used to synthesize sterically hindered bi- and triaryls by coupling various bulky, unactivated bromoxylenes and chloroxylenes with a range of phenyl boronic acids under microwave irradiation. We showed that under optimized reaction conditions, very good results can be obtained with a selection of the new phosphanes and their mononuclear palladium complexes. 相似文献
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Background
Flow cytometry based adherence assay is a potentially powerful but little used method in the study of bacterial binding to host structures. We have previously characterized a glycoprotein-binding activity in Streptococcus pyogenes called 'strepadhesin' binding to thyroglobulin, submaxillar mucin, fetuin and asialofetuin. We have identified surface-associated pullulanase (PulA) and cysteine protease (SpeB) as carriers of strepadhesin activity. In the present paper, we investigated the use of flow cytometry as a method to study the binding of Rgg, SpeB and PulA knock-out strains to cultured human epithelial cells. 相似文献60.