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101.
A Fayolle B Engelbrecht V Freycon F Mortier M Swaine M Réjou-Méchain JL Doucet N Fauvet G Cornu S Gourlet-Fleury 《PloS one》2012,7(8):e42381
Background
Understanding the factors that shape the distribution of tropical tree species at large scales is a central issue in ecology, conservation and forest management. The aims of this study were to (i) assess the importance of environmental factors relative to historical factors for tree species distributions in the semi-evergreen forests of the northern Congo basin; and to (ii) identify potential mechanisms explaining distribution patterns through a trait-based approach.Methodology/Principal Findings
We analyzed the distribution patterns of 31 common tree species in an area of more than 700,000 km2 spanning the borders of Cameroon, the Central African Republic, and the Republic of Congo using forest inventory data from 56,445 0.5-ha plots. Spatial variation of environmental (climate, topography and geology) and historical factors (human disturbance) were quantified from maps and satellite records. Four key functional traits (leaf phenology, shade tolerance, wood density, and maximum growth rate) were extracted from the literature. The geological substrate was of major importance for the distribution of the focal species, while climate and past human disturbances had a significant but lesser impact. Species distribution patterns were significantly related to functional traits. Species associated with sandy soils typical of sandstone and alluvium were characterized by slow growth rates, shade tolerance, evergreen leaves, and high wood density, traits allowing persistence on resource-poor soils. In contrast, fast-growing pioneer species rarely occurred on sandy soils, except for Lophira alata.Conclusions/Significance
The results indicate strong environmental filtering due to differential soil resource availability across geological substrates. Additionally, long-term human disturbances in resource-rich areas may have accentuated the observed patterns of species and trait distributions. Trait differences across geological substrates imply pronounced differences in population and ecosystem processes, and call for different conservation and management strategies. 相似文献102.
Lambert A. Motilal Dapeng Zhang Sue Mischke Lyndel W. Meinhardt Pathmanathan Umaharan 《Tree Genetics & Genomes》2013,9(6):1395-1411
Cacao (Theobroma cacao L.), the tree from which cocoa butter and chocolate is derived, is conserved in field genebanks. The largest of these ex situ collections in the public domain is the International Cocoa Genebank, Trinidad (ICG,T). Reduction of genetic redundancy is essential to improve the accuracy and efficiency of genebank management. This study examined the pedigree and genetic diversity in a subset of 387 accessions in this collection. Sibship reconstruction of this subset revealed 56 full-sib families nested within 189 half-sib families. Sixteen centers of interconnectivity were identified, which suggested a high level of genetic redundancy in the collection. Generally, consistent phylogenetic trees were obtained using different genetic distance measures. However, a principal coordinate analysis of the D est differentiation measure elicited the best representation of accession group clustering, and we recommend this approach when probing fine-scale genetic differentiation among cacao accessions. The composite genetic diversity of 414 cacao accessions was contained in a core set of 59 unique accessions. These results have significant implications in the conservation of genetic resources of the ICG,T and other cacao genebanks. The approach developed in this study is recommended as a strategy to curators in guiding conservation management practices of cacao and other similar ex situ genebanks. 相似文献
103.
Anne Clancy Claire Heride Adn Pinto-Fernndez Hannah Elcocks Andreas Kallinos Katherine J. Kayser-Bricker Weiping Wang Victoria Smith Simon Davis Shawn Fessler Crystal McKinnon Marie Katz Tim Hammonds Neil P. Jones Jonathan O'Connell Bruce Follows Steven Mischke Justin A. Caravella Stephanos Ioannidis Christopher Dinsmore Sunkyu Kim Axel Behrens David Komander Benedikt M. Kessler Sylvie Urb Michael J. Clague 《The Journal of cell biology》2021,220(3)
104.
Reimann-Berg N Murua Escobar H Kiefer Y Mischke R Willenbrock S Eberle N Nolte I Bullerdiek J 《Cytogenetic and genome research》2011,135(1):79-82
Human and canine lymphoid neoplasms are characterized by non-random cytogenetic abnormalities. However, due to the low mitotic activity of the B cells, cytogenetic analyses of B-cell lymphoid proliferations are difficult to perform. In the present study we stimulated canine B-cell lymphoma cells with the immunostimulatory CpG-oligonucleotide DSP30 in combination with interleukin-2 (IL-2) and obtained an adequate number of metaphases. Cytogenetic analyses revealed the loss of one X chromosome as the sole cytogenetic aberration. Chromosome analysis of the corresponding blood showed a normal female karyotype. Monosomy X as the sole clonal chromosomal abnormality is found in human hematopoietic malignancies as well, thus the dog may serve as a promising animal model. 相似文献
105.
Maanda Mudau Rachael Jacobson Nadia Minenza Lazarus Kuonza Vida Morris Heather Engelbrecht Mark P. Nicol Colleen Bamford 《PloS one》2013,8(3)
Objective
To describe an outbreak of multi-resistant Pseudomonas aeruginosa bloodstream infections (MRPA-BSI) that occurred in the haematology ward of a tertiary academic hospital in Cape Town, South Africa, and determine risk factors for acquisition of MRPA-BSI.Methods
The outbreak investigation included a search for additional cases, review of patient records, environmental and staff screening, molecular typing using pulsed-field gel electrophoresis (PFGE) and Multi-locus sequencing (MLST) and a retrospective case-control study.Results
Ten MRPA-BSI cases occurred in the haematology ward between January 2010 and January 2011. The case fatality rate was 80%. Staff screening specimens were negative for MRPA and an environmental source was not identified. PFGE showed that 9/10 isolates were related. MLST showed that 3 of these 9 isolates belonged to Sequence type (ST) 233 while the unrelated isolate belonged to ST260.Conclusion
We have described an outbreak of MRPA-BSI occurring over an extended period of time among neutropenic haematology patients. Molecular typing confirms that the outbreak was predominantly due to a single strain. The source of the outbreak was not identified, but the outbreak appears to have been controlled following intensive infection control measures. 相似文献106.
Uno et al. (1989) suggested that movements are organized such that the squared change of torque is minimized over time. Although
influential, this theory has attracted much less attention from experimental researchers than the competing minimum-jerk model
(Flash and Hogan 1985). One reason for this relative neglect has been the lack of general quantitative predictions, which
results from the belief that minimum-torque-change trajectories have to be computed numerically for individual movements and
arm-dynamical parameters. In the present paper, we show that for an important special case, that of planar horizontal movements
with one mechanical degree of freedom (DOF), it is actually possible to find an analytic expression for the predicted minimum-torque-change
trajectories. Based on this mathematical result, we derive a set of properties which are characteristic of these trajectories
and compare them to experimental data which have not previously been related to the minimum-torque-change model. Certain discrepancies
between these experimental data and minimum-torque-change model predictions are revealed.
Received: 3 September 1996 / Accepted in revised form: 7 January 1997 相似文献
107.
108.
Involvement of plasma membrane calcium influx in bacterial induction of the k/h and hypersensitive responses in tobacco 总被引:4,自引:7,他引:4
An early event in the hypersensitive response of tobacco to Pseudomonas syringae pv syringae is the initiation of a K+/H+ response characterized by specific plasma membrane K+ efflux, extracellular alkalinization, and intracellular acidification. We investigated the role of calcium in induction of these host responses. Suspension-cultured tobacco cells exhibited a baseline Ca2+ influx of 0.02 to 0.06 micromole per gram per hour as determined from 45Ca2+ uptake. Following bacterial inoculation, uptake rates began to increase coincidently with onset of the K+/H+ response. Rates increased steadily for 2 to 3 hours, reaching 0.5 to 1 micromole per gram per hour. This increased Ca2+ influx was prevented by EGTA and calcium channel blockers such as La3+, Co2+, and Cd2+ but not by verapamil and nifedipine. Lanthanum, cobalt, cadmium, and EGTA inhibited the K+/H+ response in both suspension-cultured cells and leaf discs and prevented hypersensitive cell death in leaf discs. We conclude that increased plasmalemma Ca2+ influx is required for the K+/H+ and hypersensitive responses in tobacco. 相似文献
109.
Stilwell Justin M. Rosser Thomas G. Woodyard Ethan T. Richardson Bradley M. López-Porras Adrián Leary John H. Mischke Charles C. Camus Alvin C. Griffin Matt J. 《Systematic parasitology》2021,98(4):423-441
Systematic Parasitology - Characterising myxozoan taxa parasitising fish hosts in catfish aquaculture ponds is crucial to understanding myxozoan community dynamics in these diverse and complex... 相似文献
110.
Hydroethidine has been used as a viability dye in various haemoparasites, including Plasmodium species. We compared flow cytometric quantification by hydroethidine and thiazole orange in P. falciparum. Dead parasites that did not develop or replicate exhibited high levels of DNA fragmentation and abnormal microscopic morphology, but were detected as viable ring-stage parasites by hydroethidine. Hydroethidine quantification was similar to thiazole orange, a DNA-binding dye that stains live and dead parasites. Data obtained cast concerns on hydroethidine as a suitable viability dye in P. falciparum and highlight the necessity of proper gating in flow cytometric studies quantifying parasitaemia. 相似文献