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991.
Franco Cataldo 《Chemistry and physics of lipids》2010,163(6):524-529
Unsaturated lipids when exposed to air at room temperature undergo a slow autoxidation. When fullerene C60 was dissolved in selected lipids (ethyl oleate, ethyl linoleate, linseed oil and castor oil) the spectrophotometric analysis shows that the oxidation is concentrated to C60 which is converted to an epoxide C60O. Thus, fullerene C60 displays antioxidant activity not only when dissolved in unsaturated lipids but also, more generally, when dissolved in unsaturated solvents subjected to autoxidation like, for example, in cyclohexene. The behaviour of C60 in ethyl oleate has been compared with that of the known antioxidant TMPPD (N,N′,N,N,′-tetramethyl-p-phenylenediamine) in ethyl oleate. The mechanism of the antioxidant action of C60 in lipids has been proposed. The kinetics of C60 oxidation in lipids was determined spectrophotometrically both at room temperature in the dark and under UV irradiation. The oxidized products derived from C60 photo-oxidation in lipids have been identified. 相似文献
992.
R. S. Peixoto G. M. Chaer N. Franco F. B. Reis Junior I. C. Mendes A. S. Rosado 《Antonie van Leeuwenhoek》2010,98(3):403-413
The bacterial community structures (BCSs) of Cerrado soils cultivated under conventional tillage (CT), no-tillage (NT) and
under native Cerrado (NC) vegetation were evaluated using PCR/DGGE of bacterial 16S rRNA (rrs) and rpoB genes and of Pseudomonas group genes. Soil chemical analysis, microbial biomass and the enzyme activities were also evaluated and correlated with
the BCS measurements. The multivariate ordinations of DGGE profiles showed differences between the BCS of the NC area and
those from cultivated areas. The BCSs of the CT and NT areas also differed in all DGGE fingerprints, including changes in
the profile of Pseudomonas populations, indicating that agricultural systems can also be responsible for changes within specific microbial niches, although
the clearest differences were found in the rpoB profiles. The MRPP analysis demonstrated significant differences between the BCSs from different soil layers of NT areas
based on all gene fingerprints and those of NC areas based on bacterial 16S rRNA and rpoB genes fingerprints. No differences were observed in the microbial fingerprints of CT samples from different depths, indicating
that ploughing affected the original BCS stratification. The BCS from NC areas, based on all gene fingerprints, could be related
to higher levels of soil acidity and higher amounts of MBC and of phosphatase activity. In contrast, the BCSs from cultivated
areas were related to higher levels of Ca + Mg, P and K, likely as a result of a history of chemical fertilisation in these
areas. The relationships between rpoB and Pseudomonas BCSs and all chemical and biochemical properties of soils were significant, according to a Mantel test (P < 0.05), indicating that the different changes in soil properties induced by soil use or management may drive the formation
of the soil BCS. 相似文献
993.
994.
Yaroslav Sydorskyy Tharan Srikumar Stanley M. Jeram Sarah Wheaton Franco J. Vizeacoumar Taras Makhnevych Yolanda T. Chong Anne-Claude Gingras Brian Raught 《Molecular and cellular biology》2010,30(18):4452-4462
The small ubiquitin-related modifiers (SUMOs) are evolutionarily conserved polypeptides that are covalently conjugated to protein targets to modulate their subcellular localization, half-life, or activity. Steady-state SUMO conjugation levels increase in response to many different types of environmental stresses, but how the SUMO system is regulated in response to these insults is not well understood. Here, we characterize a novel mode of SUMO system control: in response to elevated alcohol levels, the Saccharomyces cerevisiae SUMO protease Ulp1 is disengaged from its usual location at the nuclear pore complex (NPC) and sequestered in the nucleolus. We further show that the Ulp1 region previously demonstrated to interact with the karyopherins Kap95 and Kap60 (amino acids 150 to 340) is necessary and sufficient for nucleolar targeting and that enforced sequestration of Ulp1 in the nucleolus significantly increases steady-state SUMO conjugate levels, even in the absence of alcohol. We have thus characterized a novel mechanism of SUMO system control in which the balance between SUMO-conjugating and -deconjugating activities at the NPC is altered in response to stress via relocalization of a SUMO-deconjugating enzyme.The small ubiquitin-related modifiers (SUMOs) are a family of evolutionarily conserved polypeptides that are conjugated to protein targets via the concerted action of SUMO-specific E1 (activation), E2 (conjugation), and E3 (ligase) enzymes to effect changes in subcellular localization, half-life, or target activity. A family of SUMO-specific proteases act to remove the modifier from conjugates (8, 20). The SUMO system has been implicated in a variety of critical cellular functions, such as DNA repair and replication, RNA metabolism, and stress responses (8, 16, 20). Importantly, the SUMO system is highly dynamic and the SUMO pathway enzymes appear to work together to precisely control SUMO conjugate levels in the cell (8, 16, 20). However, how the SUMO system itself is regulated is poorly understood.Localization of the SUMO pathway enzymes may play an important role in SUMO system function (21). For example, the budding yeast SUMO protease Ulp1 is tethered to the nuclear face of the nuclear pore complex (NPC) via an unconventional interaction with the karyopherin Kap121 and the heterodimeric Kap95/Kap60 complex (12, 13, 23). However, this SUMO protease is not maintained exclusively at the NPC but appears to be mobile, effecting desumoylation at diverse subcellular locations: e.g., during mitosis, Saccharomyces cerevisiae Ulp1 is recruited to the septin ring to desumoylate septins (15), Schizosaccharomyces pombe Ulp1 localization is regulated throughout the cell cycle (31), and a mammalian Ulp1 homolog, SENP2, is shuttled between the nucleus and the cytoplasm (7). Consistent with these observations, SUMO conjugate levels are significantly altered in yeast strains expressing mislocalized Ulp1 (13, 37).Dramatic changes in SUMO conjugate populations have been noted in response to many different types of stresses in yeasts, mammals, and plants (9, 17, 27, 32, 38). For example, in S. cerevisiae, significantly increased steady-state SUMO conjugate levels are observed in response to elevated concentrations of ethanol (38). To better understand how the SUMO system is regulated in response to stress, we utilized alcohol as a model of a physiologically relevant stressor in yeast. Here, we demonstrate that alcohol stress results in a rapid, reversible nucleolar sequestration of Ulp1 and that enforced localization of Ulp1 in the nucleolus leads to a dramatic increase in steady-state SUMO conjugate levels. This is the first demonstration of regulated modulation of the intracellular localization of a SUMO enzyme in response to stress and thus represents a novel mechanism for SUMO system control. 相似文献
995.
José Enrique Rodríguez-Borges Xerardo García-Mera María Carmen Balo José Brea Olga Caamaño Franco Fernández Carmen López María Isabel Loza María Isabel Nieto 《Bioorganic & medicinal chemistry》2010,18(5):2001-2009
A number of novel xanthines bearing a variety of substituents at positions 1, 3, 7 and 8 were prepared and evaluated for their binding affinity to the human adenosine receptor A1, A2A, A2B and A3 subtypes. Several of the 1,3,8- and 1,3,7,8-substituted xanthines showed moderate-to-high affinity at human A2B and A1 receptors, with the most active compound (14q) having a pKi of 7.57 nM for hA2B receptors and a selectivity over hA2A receptors of 8.1-fold and hA1 receptors of 3.7-fold. 相似文献
996.
Franco Chimenti Rossella Fioravanti Adriana Bolasco Paola Chimenti Daniela Secci Francesca Rossi Matilde Yáñez Francisco Orallo Francesco Ortuso Stefano Alcaro Roberto Cirilli Rosella Ferretti M. Luisa Sanna 《Bioorganic & medicinal chemistry》2010,18(3):1273-1279
A new series of synthetic flavones, thioflavones, and flavanones has been synthesized and evaluated as potential inhibitors of monoamine oxidase isoforms (MAO-A and -B). The most active series is the flavanone one with higher selective inhibitory activity against MAO-B. Some of these flavanones (mainly the most effective) have been separated and tested as single enantiomers. In order to investigate the MAOs recognition of the most active and selective compounds, a molecular modeling study has been performed using available Protein Data Bank (PDB) structures as receptor models for docking experiments. 相似文献
997.
Nadine Katzke Solmaz Arvani René Bergmann Franco Circolone Annette Markert Vera Svensson Karl-Erich Jaeger Achim Heck Thomas Drepper 《Protein expression and purification》2010,69(2):137-146
The functional expression of heterologous genes using standard bacterial expression hosts such as Escherichia coli is often limited, e.g. by incorrect folding, assembly or targeting of recombinant proteins. Consequently, alternative bacterial expression systems have to be developed to provide novel strategies for protein synthesis exceeding the repertoire of the standard expression host E. coli.Here, we report on the construction of a novel expression system that combines the high processivity of T7 RNA polymerase with the unique physiological properties of the facultative photosynthetic bacterium Rhodobacter capsulatus. This system basically consists of a recombinant R. capsulatus T7 expression strain (R. capsulatus B10S-T7) harboring the respective polymerase gene under control of a fructose inducible promoter. In addition, a set of different broad-host-range vectors (pRho) was constructed allowing T7 RNA polymerase dependent and independent target gene expression in R. capsulatus and other Gram-negative bacteria. The expression efficiency of the novel system was studied in R. capsulatus and E. coli using the yellow fluorescent protein (YFP) as model protein. Expression levels were comparable in both expression hosts and yielded up to 80 mg/l YFP in phototrophically grown R. capsulatus cultures. This result clearly indicates that the novel R. capsulatus-based expression system is well suited for the high-level expression of soluble proteins. 相似文献
998.
The power of molecular genetic techniques to address ecological research questions has opened a distinct interdisciplinary
research area collectively referred to as molecular ecology. Molecular ecology combines aspects of diverse research fields
like population and evolutionary genetics, as well as biodiversity, conservation biology, behavioural ecology, or species-habitat
interactions. Molecular techniques detect specific DNA sequence characteristics that are used as genetic markers to discriminate
individuals or taxonomic groups, for instance in analyses of population and community structures, for elucidation of phylogenetic
relationships, or for the characterization and monitoring of specific strains in the environment. Here, we summarize the PCR-based
molecular techniques used in molecular ecological research on fungal entomopathogens and discuss novel techniques that may
have relevance to the studies of entomopathogenic fungi in the future. We discuss the flow chart of the molecular ecology
approaches and we highlight some of the critical steps involved. There are still many unresolved questions in the understanding
of the ecology of fungal entomopathogens. These include population characteristics and relations of genotypes and habitats
as well as host-pathogen interactions. Molecular tools can provide substantial support for ecological research and offer insight
into this far inaccessible systems. Application of molecular ecology approaches will stimulate and accelerate new research
in the field of entomophathogen ecology. 相似文献
999.
A. Campos P. K. Carvajal‐Vallejos E. Villalobos C. F. Franco A. M. Almeida A. V. Coelho J. M. Torné M. Santos 《Plant biology (Stuttgart, Germany)》2010,12(5):708-716
Chloroplast transglutaminase (chlTGase) activity is considered to play a significant role in response to a light stimulus and photo‐adaptation of plants, but its precise function in the chloroplast is unclear. The characterisation, at the proteomic level, of the chlTGase interaction with thylakoid proteins and demonstration of its association with photosystem II (PSII) protein complexes was accomplished with experiments using maize thylakoid protein extracts. By means of a specific antibody designed against the C‐terminal sequence of the maize TGase gene product, different chlTGase forms were immunodetected in thylakoid membrane extracts from three different stages of maize chloroplast differentiation. These bands co‐localised with those of lhcb 1, 2 and 3 antenna proteins. The most significant, a 58 kDa form present in mature chloroplasts, was characterised using biochemical and proteomic approaches. Sequential fractionation of thylakoid proteins from light‐induced mature chloroplasts showed that the 58 kDa form was associated with the thylakoid membrane, behaving as a soluble or peripheral membrane protein. Two‐dimensional gel electrophoresis discriminated, for the first time, the 58‐kDa band in two different forms, probably corresponding to the two different TGase cDNAs previously cloned. Electrophoretic separation of thylakoid proteins in native gels, followed by LC‐MS mass spectrometry identification of protein complexes indicated that maize chlTGase forms part of a specific PSII protein complex, which includes LHCII, ATPase and pSbS proteins. The results are discussed in relation to the interaction between these proteins and the suggested role of the enzyme in thylakoid membrane organisation and photoprotection. 相似文献
1000.
Sara Borin Stefano Ventura Fulvia Tambone Francesca Mapelli Florence Schubotz Lorenzo Brusetti Barbara Scaglia Luigi P. D'Acqui Bjørn Solheim Silvia Turicchia Ramona Marasco Kai‐Uwe Hinrichs Franco Baldi Fabrizio Adani Daniele Daffonchio 《Environmental microbiology》2010,12(2):293-303
During primary colonization of rock substrates by plants, mineral weathering is strongly accelerated under plant roots, but little is known on how it affects soil ecosystem development before plant establishment. Here we show that rock mineral weathering mediated by chemolithoautotrophic bacteria is associated to plant community formation in sites recently released by permanent glacier ice cover in the Midtre Lovénbreen glacier moraine (78°53′N), Svalbard. Increased soil fertility fosters growth of prokaryotes and plants at the boundary between sites of intense bacterial mediated chemolithotrophic iron‐sulfur oxidation and pH decrease, and the common moraine substrate where carbon and nitrogen are fixed by cyanobacteria. Microbial iron oxidizing activity determines acidity and corresponding fertility gradients, where water retention, cation exchange capacity and nutrient availability are increased. This fertilization is enabled by abundant mineral nutrients and reduced forms of iron and sulfur in pyrite minerals within a conglomerate type of moraine rock. Such an interaction between microorganisms and moraine minerals determines a peculiar, not yet described model for soil genesis and plant ecosystem formation with potential past and present analogues in other harsh environments with similar geochemical settings. 相似文献