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131.
A comparative analysis reveals weak relationships between ecological factors and beta diversity of stream insect metacommunities at two spatial levels 下载免费PDF全文
Florian Altermatt Salman A. Al‐Shami David G. Angeler Núria Bonada Cecilia Brand Marcos Callisto Karl Cottenie Olivier Dangles David Dudgeon Andrea Encalada Emma Göthe Mira Grönroos Neusa Hamada Dean Jacobsen Victor L. Landeiro Raphael Ligeiro Renato T. Martins María Laura Miserendino Che Salmah Md Rawi Marciel E. Rodrigues Fabio de Oliveira Roque Leonard Sandin Denes Schmera Luciano F. Sgarbi John P. Simaika Tadeu Siqueira Ross M. Thompson Colin R. Townsend 《Ecology and evolution》2015,5(6):1235-1248
The hypotheses that beta diversity should increase with decreasing latitude and increase with spatial extent of a region have rarely been tested based on a comparative analysis of multiple datasets, and no such study has focused on stream insects. We first assessed how well variability in beta diversity of stream insect metacommunities is predicted by insect group, latitude, spatial extent, altitudinal range, and dataset properties across multiple drainage basins throughout the world. Second, we assessed the relative roles of environmental and spatial factors in driving variation in assemblage composition within each drainage basin. Our analyses were based on a dataset of 95 stream insect metacommunities from 31 drainage basins distributed around the world. We used dissimilarity‐based indices to quantify beta diversity for each metacommunity and, subsequently, regressed beta diversity on insect group, latitude, spatial extent, altitudinal range, and dataset properties (e.g., number of sites and percentage of presences). Within each metacommunity, we used a combination of spatial eigenfunction analyses and partial redundancy analysis to partition variation in assemblage structure into environmental, shared, spatial, and unexplained fractions. We found that dataset properties were more important predictors of beta diversity than ecological and geographical factors across multiple drainage basins. In the within‐basin analyses, environmental and spatial variables were generally poor predictors of variation in assemblage composition. Our results revealed deviation from general biodiversity patterns because beta diversity did not show the expected decreasing trend with latitude. Our results also call for reconsideration of just how predictable stream assemblages are along ecological gradients, with implications for environmental assessment and conservation decisions. Our findings may also be applicable to other dynamic systems where predictability is low. 相似文献
132.
Claudia T Guimaraes Christiano C Simoes Maria Marta Pastina Lyza G Maron Jurandir V Magalhaes Renato CC Vasconcellos Lauro JM Guimaraes Ubiraci GP Lana Carlos FS Tinoco Roberto W Noda Silvia N Jardim-Belicuas Leon V Kochian Vera MC Alves Sidney N Parentoni 《BMC genomics》2014,15(1)
Background
Aluminum (Al) toxicity is an important limitation to food security in tropical and subtropical regions. High Al saturation on acid soils limits root development, reducing water and nutrient uptake. In addition to naturally occurring acid soils, agricultural practices may decrease soil pH, leading to yield losses due to Al toxicity. Elucidating the genetic and molecular mechanisms underlying maize Al tolerance is expected to accelerate the development of Al-tolerant cultivars.Results
Five genomic regions were significantly associated with Al tolerance, using 54,455 SNP markers in a recombinant inbred line population derived from Cateto Al237. Candidate genes co-localized with Al tolerance QTLs were further investigated. Near-isogenic lines (NILs) developed for ZmMATE2 were as Al-sensitive as the recurrent line, indicating that this candidate gene was not responsible for the Al tolerance QTL on chromosome 5, qALT5. However, ZmNrat1, a maize homolog to OsNrat1, which encodes an Al3+ specific transporter previously implicated in rice Al tolerance, was mapped at ~40 Mbp from qALT5. We demonstrate for the first time that ZmNrat1 is preferentially expressed in maize root tips and is up-regulated by Al, similarly to OsNrat1 in rice, suggesting a role of this gene in maize Al tolerance. The strongest-effect QTL was mapped on chromosome 6 (qALT6), within a 0.5 Mbp region where three copies of the Al tolerance gene, ZmMATE1, were found in tandem configuration. qALT6 was shown to increase Al tolerance in maize; the qALT6-NILs carrying three copies of ZmMATE1 exhibited a two-fold increase in Al tolerance, and higher expression of ZmMATE1 compared to the Al sensitive recurrent parent. Interestingly, a new source of Al tolerance via ZmMATE1 was identified in a Brazilian elite line that showed high expression of ZmMATE1 but carries a single copy of ZmMATE1.Conclusions
High ZmMATE1 expression, controlled either by three copies of the target gene or by an unknown molecular mechanism, is responsible for Al tolerance mediated by qALT6. As Al tolerant alleles at qALT6 are rare in maize, marker-assisted introgression of this QTL is an important strategy to improve maize adaptation to acid soils worldwide.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-15-153) contains supplementary material, which is available to authorized users. 相似文献133.
Efthalia K. Chatziefstratiou Gil Bohrer Anthony S. Bova Ravishankar Subramanian Renato P. M. Frasson Amy Scherzer Bret W. Butler Matthew B. Dickinson 《PloS one》2013,8(7)
FireStem2D, a software tool for predicting tree stem heating and injury in forest fires, is a physically-based, two-dimensional model of stem thermodynamics that results from heating at the bark surface. It builds on an earlier one-dimensional model (FireStem) and provides improved capabilities for predicting fire-induced mortality and injury before a fire occurs by resolving stem moisture loss, temperatures through the stem, degree of bark charring, and necrotic depth around the stem. We present the results of numerical parameterization and model evaluation experiments for FireStem2D that simulate laboratory stem-heating experiments of 52 tree sections from 25 trees. We also conducted a set of virtual sensitivity analysis experiments to test the effects of unevenness of heating around the stem and with aboveground height using data from two studies: a low-intensity surface fire and a more intense crown fire. The model allows for improved understanding and prediction of the effects of wildland fire on injury and mortality of trees of different species and sizes. 相似文献
134.
Phytotoxic Effects and Phytochemical Fingerprinting of Hydrodistilled Oil,Enriched Fractions,and Isolated Compounds Obtained from Cryptocarya massoy (Oken) Kosterm. Bark 下载免费PDF全文
Enrico Rolli Matteo Marieschi Silvia Maietti Alessandra Guerrini Alessandro Grandini Gianni Sacchetti Renato Bruni 《化学与生物多样性》2016,13(1):66-76
The hydrodistilled oil of Cryptocarya massoy bark was characterized by GC‐FID and GC/MS analyses, allowing the identification of unusual C10 massoia lactone ( 3 , 56.2%), C12 massoia lactone ( 4 , 16.5%), benzyl benzoate ( 1 , 12.7%), C8 massoia lactone (3.4%), δ‐decalactone ( 5 , 1.5%), and benzyl salicylate ( 2 , 1.8%) as main constituents. The phytotoxic activities of the oil, three enriched fractions (lactone‐rich, ester‐rich, and sesquiterpene‐rich), and four constituents (compounds 1, 2, 5 , and δ‐dodecalactone ( 6 )) against Lycopersicon esculentum and Cucumis sativus seeds and seedlings were screened. At a concentration of 1000 μl/l, the essential oil and the massoia lactone‐rich fraction caused a complete inhibition of the germination of both seeds, and, when applied on tomato plantlets, they induced an 85 and 100% dieback, respectively. These performances exceeded those of the well‐known phytotoxic essential oils of Syzygium aromaticum and Cymbopogon citratus, already used in commercial products for the weed and pest management. The same substances were also evaluated against four phytopathogenic bacteria and ten phytopathogenic fungi, providing EC50 values against the most susceptible strains in the 100–500 μl/l range for the essential oil and in the 10–50 μl/l range for compound 6 and the lactone‐rich fraction. The phytotoxic behavior was related mainly to massoia lactones and benzyl esters, while a greater amount of 6 may infer a good activity against some phytopathogenic fungi. Further investigations of these secondary metabolites are warranted, to evaluate their use as natural herbicides. 相似文献
135.
Alberto M. Martelli Lucia Manzoli Silvia Rubbini Anna Maria Billi Renato Bareggi Lucio Cocco 《Biology of the cell / under the auspices of the European Cell Biology Organization》1995,83(1):15-22
Summary— Using two-dimensional polyacrylamide gels stained with Coomassie blue we have studied the protein composition of the nuclear matrix obtained from mouse erythroleukemic nuclei kept at O°C throughout the isolation procedure to prepare the high ionic strength resistant fraction (control matrix) or stabilized in vitro or in vivo by different procedures prior to subfractionation (ie 37°C incubation of isolated nuclei; sodium tetrathionate exposure of purified nuclei; heat shock of intact cells). When the matrix obtained from 37°C incubated nuclei was compared with the control matrix, striking differences in the polypeptide pattern were seen if the protein was obtained in both cases from an equivalent number of nuclei. On the other hand, if the same amount of protein for both the samples was applied to the gels the differences were less evident. Sodium tetrathionate stabilization of isolated nuclei and heat shock of intact cells produced a matrix protein pattern that was very similar and differed from that of the in vitro heat-exposed matrix. Using specific polyclonal antisera, we demonstrate that nucleolar proteins B23/numatrin and C23/nucleolin were very abundant in the matrix obtained from chemically-treated nuclei or in vivo heat-stabilized nuclei but were recovered in very small amounts (B23) or completely absent (C23) in the matrix prepared from nuclei heated to 37°C in vitro. Differences were seen also in the recovery of nuclear lamins, and especially lamin B, that was poorly represented in the sodium tetrathionate-stabilized matrix. The results demonstrate that in mouse erythroleukemia cells the increased recovery of nuclear matrix protein that is seen after in vitro heating of isolated nuclei is predominantly due to an additional recovery of the same types of polypeptides that are detected also in the absence of such a treatment. The data also indicate that in vivo heat shock of intact cells produces a nuclear matrix protein pattern that is more similar to the pattern seen after stabilization of purified nuclei with sodium tetrathionate and differs significantly from that obtained by exposing nuclei to 37°C in vitro, unlike to that what previous reports have indicated. 相似文献
136.
137.
Tatiane A. Paixão Marcelo C. C. Malta Semíramis A. Soave Herlandes P. Tinoco Maria E.L.T. Costa Angela T. Pessanha Rodrigo O.S. Silva Fernanda M. Coura Luciana F. Costa Andreia P. Turchetti Francisco C.F. Lobato Marilia M. Melo Marcos B. Heinemann Renato L. Santos 《Journal of medical primatology》2014,43(2):118-121
138.
Olivier Maurin Artemis Anest Sidonie Bellot Edward Biffin Grace Brewer Tristan Charles-Dominique Robyn S. Cowan Steven Dodsworth Niroshini Epitawalage Berta Gallego Augusto Giaretta Renato Goldenberg Deise J.P. Gonçalves Shirley Graham Peter Hoch Fiorella Mazine Yee Wen Low Catherine McGinnie Fabián A. Michelangeli Sarah Morris Darin S. Penneys Oscar Alejandro Pérez Escobar Yohan Pillon Lisa Pokorny Gustavo Shimizu Vanessa G. Staggemeier Andrew H. Thornhill Kyle W. Tomlinson Ian M. Turner Thais Vasconcelos Peter G. Wilson Alexandre R. Zuntini William J. Baker Félix Forest Eve Lucas 《American journal of botany》2021,108(7):1087-1111
139.
Xavier AR Roselino JE Resano NM Garófalo MA Migliorini RH Kettelhut Ido C 《Canadian journal of physiology and pharmacology》2002,80(2):164-169
Although the conversion of lactate to glycogen (glyconeogenesis) in muscle was demonstrated a long time ago, the biochemical reactions responsible for this process are still a controversial matter. In the present study, advantage was taken from the specific inhibition induced by phenylalanine on muscle pyruvate kinase (PK) to investigate the role of reverse PK activity in muscle glyconeogenesis. Addition of phenylalanine to the incubation medium of a preparation of isolated, intact skeletal muscles that maintain metabolic activity for several hours reduced by 50% the rate of incorporation of [14C]lactate or [14C]bicarbonate into muscle glycogen. Muscle extracts presented high levels of maximal activity of PK in the reverse direction, which was completely blocked in the presence of phenylalanine. In contrast, mercaptopicolinic acid, an inhibitor of phosphoenolpyruvate carboxykinase (PEPCK), did not affect the incorporation of 14C from either lactate or bicarbonate into muscle glycogen. Maximal PEPCK activity was much lower in muscle extracts than in gluconeogenic or glyceroneogenic tissues and was suppressed in the presence of mercaptopicolinic acid. The data suggest that a reversal of the metabolic flux through the reaction catalyzed by PK contributes to the accumulation of lactate-derived glycogen that occurs in skeletal muscle under certain physiological conditions. 相似文献
140.
Hüe S Monteiro RC Berrih-Aknin S Caillat-Zucman S 《Journal of immunology (Baltimore, Md. : 1950)》2003,171(4):1909-1917
The nonclassical MHC class I molecule MHC class I-related chain A (MICA) interacts with the NKG2D receptor expressed at the surface of most peripheral CD8 T cells, gammadelta T cells, and NK cells. We investigated the role of MICA-NKG2D interactions in the selection or maturation of the T cell repertoire within the thymus using MICA tetramers and anti-MICA mAbs. MICA tetramers identified a small population of late stage CD8 single-positive, CD45RA(+) CD62L(+) CCR7(+) CD69(-) thymocytes, a phenotype compatible with that of fully mature CD8(+) cells ready to emigrate to the periphery as naive cells. MICA molecules were expressed in the outer layer of Hassal's corpuscles within the medulla of normal thymus. In thymomas, an overexpression of MICA in cortical and medullar epithelial cells was observed. This was associated with a decreased percentage of NKG2D-positive thymocytes, which expressed a less mature phenotype than in normal thymus. These results indicate that CD8(+) thymocytes up-regulate NKG2D as they complete their developmental program before leaving the thymic medulla to seed the periphery, and identify NKG2D as a potential regulator of the developmental processes in T cells that are essential for immune homeostasis. 相似文献