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991.
Claudia Dragonetti Stefania Righetto Dominique Roberto Renato Ugo Adriana Valore Francesco Demartin Filippo De Angelis Antonio Sgamellotti Simona Fantacci 《Inorganica chimica acta》2008,361(14-15):4070-4076
[Ir(cyclometallated 4,5-diphenyl-2-methyl-thiazole)2(5-R-1,10-phenanthroline)][PF6] (R = CH3, NO2) complexes were prepared and fully characterized, the structure of the complex with 5-CH3-1,10-phenanthroline being also determined by X-ray diffraction. The emission properties of both complexes have been investigated and their second-order nonlinear optical (NLO) response has been determined experimentally by the EFISH technique and found to be similar but slightly lower than that of related [Ir(ppy)2(5-R-1,10-phenanthroline)][PF6] (ppy = cyclometallated 2-phenylpyridine), characterized by one of the highest second-order NLO response ever reported for a metal complex. In the complexes, SOS/TDDFT calculations show that the large and negative sign of the measured hyperpolarizability is mainly due to the significant contribution of rather intense MLCT transitions involving the phenanthroline as acceptor ligand. 相似文献
992.
Sugiana C Pagliarini DJ McKenzie M Kirby DM Salemi R Abu-Amero KK Dahl HH Hutchison WM Vascotto KA Smith SM Newbold RF Christodoulou J Calvo S Mootha VK Ryan MT Thorburn DR 《American journal of human genetics》2008,83(4):468-478
Complex I (NADH:ubiquinone oxidoreductase) is the first and largest multimeric complex of the mitochondrial respiratory chain. Human complex I comprises seven subunits encoded by mitochondrial DNA and 38 nuclear-encoded subunits that are assembled together in a process that is only partially understood. To date, mutations causing complex I deficiency have been described in all 14 core subunits, five supernumerary subunits, and four assembly factors. We describe complex I deficiency caused by mutation of the putative complex I assembly factor C20orf7. A candidate region for a lethal neonatal form of complex I deficiency was identified by homozygosity mapping of an Egyptian family with one affected child and two affected pregnancies predicted by enzyme-based prenatal diagnosis. The region was confirmed by microcell-mediated chromosome transfer, and 11 candidate genes encoding potential mitochondrial proteins were sequenced. A homozygous missense mutation in C20orf7 segregated with disease in the family. We show that C20orf7 is peripherally associated with the matrix face of the mitochondrial inner membrane and that silencing its expression with RNAi decreases complex I activity. C20orf7 patient fibroblasts showed an almost complete absence of complex I holoenzyme and were defective at an early stage of complex I assembly, but in a manner distinct from the assembly defects caused by mutations in the assembly factor NDUFAF1. Our results indicate that C20orf7 is crucial in the assembly of complex I and that mutations in C20orf7 cause mitochondrial disease. 相似文献
993.
Nutrient and carbon relations in subalpine dwarf shrubs after neighbour removal or fertilization in northern Italy 总被引:3,自引:0,他引:3
Two subalpine dwarf-shrub heath communities with differing levels of soil nutrient availability were subjected to a 3-year experimental manipulation, including nutrient addition or removal of one of the two co-dominant species from each community. The main objective of our study was to assess the relative importance of interspecific competition versus nutrient limitation in relation to soil fertility. We also aimed to investigate if and to what extent current-year shoot size, leaf-based rates of net photosynthesis and foliar nutrient status accounted for the observed changes in the aboveground biomass of the shrubs. At the end of the experiment, neighbour removal increased the aboveground biomass of all shrubs, especially in the more fertile community, while fertilization did not. We concluded that: (1) competition is more effective than nutrient limitation in structuring the vegetation of subalpine heathlands; and (2) competition intensity is stronger in the more fertile community. The observed patterns of variations in aboveground biomass were not consistently related to net photosynthetic rates, size of individual shoots and foliar nutrient status. Hence, we also concluded that the growth response of dwarf shrubs to altered environmental conditions is primarily determined by developmental plasticity. 相似文献
994.
995.
Hannah K. Delille Renato Alves Michael Schrader 《Histochemistry and cell biology》2009,131(4):441-446
Peroxisomes and mitochondria are metabolically linked organelles, which are crucial to human health and development. The search
for components involved in their dynamics and maintenance led to the interesting finding that mitochondria and peroxisomes
share components of their division machinery. Recently, it became clear that this is a common strategy used by mammals, fungi
and plants. Furthermore, a closer interrelationship between peroxisomes and mitochondria has been proposed, which might have
an impact on functionality and disease conditions. Here, we briefly highlight the major findings, views and open questions
concerning peroxisomal formation, division, and interrelationship with mitochondria.
Presented at the 50th Anniversary Symposium of the Society for Histochemistry, Interlaken, Switzerland, October 1–4, 2008. 相似文献
996.
Renato Pérez Rosés Nelson Pérez Guerra 《World journal of microbiology & biotechnology》2009,25(11):1929-1939
Synthesis of amylase by Aspergillus niger strain UO-01 under solid-state fermentation with sugarcane bagasse was optimized by using response surface methodology and empirical modelling. The process parameters tested were particle size of sugarcane bagasse, incubation temperature and pH, moisture level of solid support material and the concentrations of inoculum, total sugars, nitrogen and phosphorous. The optimum conditions for high amylase production (457.82 EU/g of dry support) were particle size of bagasse in the range of 6–8 mm, incubation temperature and pH: 30.2°C and 6.0, moisture content of bagasse: 75.3%, inoculum concentration: 1 × 107 spores/g of dry support and concentrations of starch, yeast extract and KH2PO4: 70.5, 11.59 and 9.83 mg/g of dry support, respectively. After optimization, enzyme production was assayed at the optimized conditions. The results obtained corroborate the effectiveness and reliability of the empirical models obtained. 相似文献
997.
PPARα Antagonist AA452 Triggers Metabolic Reprogramming and Increases Sensitivity to Radiation Therapy in Human Glioblastoma Primary Cells 下载免费PDF全文
Elisabetta Benedetti Michele d'Angelo Alessandra Ammazzalorso Giovanni Luca Gravina Chiara Laezza Andrea Antonosante Gloria Panella Benedetta Cinque Loredana Cristiano Anne Chloè Dhez Carlo Astarita Renato Galzio Maria Grazia Cifone Rodolfo Ippoliti Rosa Amoroso Ernesto Di Cesare Antonio Giordano Annamaria Cimini 《Journal of cellular physiology》2017,232(6):1458-1466
998.
Marques MA Neves-Ferreira AG da Silveira EK Valente RH Chapeaurouge A Perales J da Silva Bernardes R Dobos KM Spencer JS Brennan PJ Pessolani MC 《Proteomics》2008,8(12):2477-2491
The complete sequence of the Mycobacterium leprae genome, an obligate intracellular pathogen, shows a dramatic reduction of functional genes, with a coding capacity of less than 50%. Despite this massive gene decay, the leprosy bacillus has managed to preserve a minimal gene set, most of it shared with Mycobacterium tuberculosis, allowing its survival in the host with ensuing pathological manifestations. Thus, the identification of proteins that are actually expressed in vivo by M. leprae is of high significance in understanding obligate, intracellular mycobacterial pathogenesis. In this study, a high-throughput proteomic approach was undertaken resulting in the identification of 218 new M. leprae proteins. Of these, 60 were in the soluble/cytosol fraction, 98 in the membrane and 104 in the cell wall. Although several proteins were identified in more than one subcellular fraction, the majority were unique to one. As expected, a high percentage of these included enzymes responsible for lipid biosynthesis and degradation, biosynthesis of the major components of the mycobacterial cell envelope, proteins involved in transportation across lipid barriers, and lipoproteins and transmembrane proteins with unknown functions. The data presented in this study contribute to our understanding of the in vivo composition and physiology of the mycobacterial cell envelope, a compartment known to play a major role in bacterial pathogenesis. 相似文献
999.
Chave J Condit R Muller-Landau HC Thomas SC Ashton PS Bunyavejchewin S Co LL Dattaraja HS Davies SJ Esufali S Ewango CE Feeley KJ Foster RB Gunatilleke N Gunatilleke S Hall P Hart TB Hernández C Hubbell SP Itoh A Kiratiprayoon S Lafrankie JV Loo de Lao S Makana JR Noor MN Kassim AR Samper C Sukumar R Suresh HS Tan S Thompson J Tongco MD Valencia R Vallejo M Villa G Yamakura T Zimmerman JK Losos EC 《PLoS biology》2008,6(3):e45
In Amazonian tropical forests, recent studies have reported increases in aboveground biomass and in primary productivity, as well as shifts in plant species composition favouring fast-growing species over slow-growing ones. This pervasive alteration of mature tropical forests was attributed to global environmental change, such as an increase in atmospheric CO2 concentration, nutrient deposition, temperature, drought frequency, and/or irradiance. We used standardized, repeated measurements of over 2 million trees in ten large (16–52 ha each) forest plots on three continents to evaluate the generality of these findings across tropical forests. Aboveground biomass increased at seven of our ten plots, significantly so at four plots, and showed a large decrease at a single plot. Carbon accumulation pooled across sites was significant (+0.24 MgC ha−1 y−1, 95% confidence intervals [0.07, 0.39] MgC ha−1 y−1), but lower than reported previously for Amazonia. At three sites for which we had data for multiple census intervals, we found no concerted increase in biomass gain, in conflict with the increased productivity hypothesis. Over all ten plots, the fastest-growing quartile of species gained biomass (+0.33 [0.09, 0.55] % y−1) compared with the tree community as a whole (+0.15 % y−1); however, this significant trend was due to a single plot. Biomass of slow-growing species increased significantly when calculated over all plots (+0.21 [0.02, 0.37] % y−1), and in half of our plots when calculated individually. Our results do not support the hypothesis that fast-growing species are consistently increasing in dominance in tropical tree communities. Instead, they suggest that our plots may be simultaneously recovering from past disturbances and affected by changes in resource availability. More long-term studies are necessary to clarify the contribution of global change to the functioning of tropical forests. 相似文献
1000.
Abstract. Gradients in acidity‐alkalinity and nutrient availability were studied in 2 Sphagnum‐dominated peatlands on the southeastern Italian Alps. Decreasing concentrations of most mineral elements (Ca2+, Mg2+, Mn2+, Al3+ and Si4+) in pore water indicated a progressively lower influx of mineral‐soil water from the slightly minerotrophic conditions in the peatland margins to ombrogenous conditions in the central part of the peatlands. This was paralleled by decreasing concentrations of ash, bulk density, Ca, Fe and, partly, Mn in the peat. The nutrient gradient, as defined by pore water concentrations of N and P, was largely independent of the acidity‐ alkalinity gradient: NO3‐ and PO43‐ had similar concentrations throughout the gradient, whereas NH4+ concentrations increased with increasing pore‐water pH. In contrast, the peat nutrient gradient coincided with the acidity‐alkalinity gradient, with total concentrations of N and P decreasing from the margin to the centre. Bryophytes and vascular plants had different responses along the acidity‐alkalinity gradient and the nutrient gradient. Bryophyte distribution reflected the acidity‐alkalinity gradient both in pore water and in peat. Vascular plant distribution was mainly influenced by variations in nutrient availability. 相似文献