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排序方式: 共有281条查询结果,搜索用时 31 毫秒
1.
Distinct effects of climate warming on populations of silver fir (Abies alba) across Europe 下载免费PDF全文
2.
An Ustilago maydis ergosterol biosynthesis mutant (A14) which is partially blocked in sterol 14alpha-demethylase (P45014DM) activity is described. This mutant accumulated the abnormal 14alpha-methyl sterols, eburicol, 14alpha-methylfecosterol, and obtusifoliol, along with significant amounts of ergosterol. Although the A14 mutant grew nearly as well as the wild type, it was impaired in cell extension growth, which indicated a dysfunction in apical cell wall synthesis. The mutant was also found to be hypersensitive to the azole fungicides penconazole and tebuconazole. 相似文献
3.
J. M. Barrasa S. Camarero A. T. Martínez K. Ruel 《Applied microbiology and biotechnology》1995,43(4):766-770
The ultrastructural patterns characterizing wheat straw degradation by the ligninolytic fungi Phanerochaete chrysosporium and Trametes versicolor were studied. During fungal attack, the less lignified tissues were degraded first, whereas the xylematic and sclerenchymatic fibers underwent a delayed attack. In straw samples degraded by T. versicolor, partial delignification, defibrillation and swelling of cell walls, often causing separation between primary and secondary walls, were observed. By contrast, the formation of erosions and fissures, with minor lignin removal, characterized the attack to the cell wall by P. chrysosporium. At an advanced stage of decay, KMnO4 staining demonstrated abundant electron-dense material around hyphae and in the proximity of the cell-wall surface. In the case of P. chrysosporium, spherical black bodies were found in the erosions and fissures produced during fungal attack. 相似文献
4.
5.
González-Diez B Cavia M Torres G Abaigar P Camarero V Muñiz P 《Molecular biology reports》2012,39(1):629-634
In the last few years haemodiafiltration with on-line regeneration of ultrafiltrate (HFR) has been shown to have a positive
impact on inflammation and oxidative stress biomarkers, but its effect on antioxidant levels and on oxidative damage to biomolecules
in the long-term is still unknown. This is a randomised clinical study over 12 months involving 40 patients on haemodialysis,
comparing the effect of HFR (n = 25) dialysis with haemodialysis with polysulfone (HD-PS, n = 15) on oxidative stress. Total antioxidant capacity, enzymatic antioxidant [superoxide dismutase (SOD), catalase and glutathione
peroxidase], non-enzymatic (GSH) and biomarkers of oxidative stress (TBARs, carbonyl groups and 8-OH-dG) were evaluated. The
antioxidant activity decreased in the lymphocytes of patients dialysed with HFR, with a significant decrease in the enzyme
SOD. In the oxidative stress biomarkers, an increase was seen in the levels of 8-OH-dG in patients on HD-PS dialysis but not
in those treated with HFR. Throughout the year the changes in antioxidant levels and biomarkers of oxidative damage in patients
dialysed with HFR were generally more modest and fluctuated less than those dialysed with HD-PS. Our study indicates that,
in general, long-term dialysis with HFR does not modified antioxidant parameters or increases the oxidative damage to biomolecules.
The HFR showed to be a biocompatible technique for long-term dialysis. 相似文献
6.
Arun K. Bose Arthur Gessler Andreas Bolte Alessandra Bottero Allan Buras Maxime Cailleret J. Julio Camarero Matthias Haeni Ana‐Maria Here Andrea Hevia Mathieu Lvesque Juan C. Linares Jordi Martinez‐Vilalta Luis Matías Annette Menzel Raúl Snchez‐Salguero Matthias Saurer Michel Vennetier Daniel Ziche Andreas Rigling 《Global Change Biology》2020,26(8):4521-4537
Global climate change is expected to further raise the frequency and severity of extreme events, such as droughts. The effects of extreme droughts on trees are difficult to disentangle given the inherent complexity of drought events (frequency, severity, duration, and timing during the growing season). Besides, drought effects might be modulated by trees’ phenotypic variability, which is, in turn, affected by long‐term local selective pressures and management legacies. Here we investigated the magnitude and the temporal changes of tree‐level resilience (i.e., resistance, recovery, and resilience) to extreme droughts. Moreover, we assessed the tree‐, site‐, and drought‐related factors and their interactions driving the tree‐level resilience to extreme droughts. We used a tree‐ring network of the widely distributed Scots pine (Pinus sylvestris) along a 2,800 km latitudinal gradient from southern Spain to northern Germany. We found that the resilience to extreme drought decreased in mid‐elevation and low productivity sites from 1980–1999 to 2000–2011 likely due to more frequent and severe droughts in the later period. Our study showed that the impact of drought on tree‐level resilience was not dependent on its latitudinal location, but rather on the type of sites trees were growing at and on their growth performances (i.e., magnitude and variability of growth) during the predrought period. We found significant interactive effects between drought duration and tree growth prior to drought, suggesting that Scots pine trees with higher magnitude and variability of growth in the long term are more vulnerable to long and severe droughts. Moreover, our results indicate that Scots pine trees that experienced more frequent droughts over the long‐term were less resistant to extreme droughts. We, therefore, conclude that the physiological resilience to extreme droughts might be constrained by their growth prior to drought, and that more frequent and longer drought periods may overstrain their potential for acclimation. 相似文献
7.
Rüdiger Ortiz-Álvarez Joan Cáliz Lluís Camarero Emilio O. Casamayor 《Environmental microbiology》2020,22(1):297-309
Microbial communities in natural ecosystems are subject to strong ecological rules. The study of local communities along a regional metacommunity can reveal patterns of community assembly, and disentangle the underlying ecological processes. In particular, we seek drivers of community assembly at the regional scale using a large lacustrine dataset (>300 lakes) along the geographical, limnological and physico-chemical gradients in the Pyrenees. By using high throughput amplicon sequencing of the 16S rRNA gene, and inferring environmental sources of bacterial immigrants, we showed that surface aquatic bacterial assemblages were strongly influenced by terrestrial populations from soil, biofilms or sediments, and primarily selected by a pH-alkalinity gradient. Indeed, source proportions explained 27% of the community variation, and chemistry 15% of the total variation, half of it shared with the sources. Major taxonomic groups such as Verrucomicrobia, Actinobacteria and Bacteroidetes showed higher aquatic affinities than Parcubacteria, Gammaproteobacteria, Alphaproteobacteria or Betaproteobacteria, which may be recruited and selected through different hydrographic habitats. A regional fingerprint was observed with lower alpha diversity and higher beta diversity in the central Pyrenees than in both ends. We suggest an ecological succession process, likely influenced by complex interactions of environmental source dispersal and environmental filtering along the mountain range geography. 相似文献
8.
Olga P. Nyssen Angeles Perez‐Aisa Luis Rodrigo Manuel Castro Pilar Mata Romero Juan Ortuo Jesus Barrio Jose Maria Huguet Ines Modollel Noelia Alcaide Alfredo Lucendo Xavier Calvet Monica Perona Barbara Gomez Blas Jose Gomez Rodriguez Pilar Varela Manuel Jimenez‐Moreno Manuel Dominguez‐Cajal Liliana Pozzati Diego Burgos Luis Bujanda Jenifer Hinojosa Javier Molina‐Infante Tommaso Di Maira Luis Ferrer Luis Fernndez‐Salazar Ariadna Figuerola Llucia Tito Cristobal de la Coba Judith Gomez‐Camarero Nuria Fernandez Maria Caldas Ana Garre Elena Resina Ignasi Puig Colm OMorain Francis Megraud Javier P. Gisbert 《Helicobacter》2020,25(5)
9.
JA Kiernan 《Biotechnic & histochemistry》2013,88(5-6):203-210
Hexazonium pararosaniline is a valuable reagent that has been used in enzyme activity histochemistry for 50 years. It is an aqueous solution containing the tris-diazonium ion derived from pararosaniline, an aminotriarylmethane dye, and it contains an excess of nitrous acid that was not consumed in the diazotization reaction. Other investigators have found that immersion for 2 min in an acidic (pH 3.5) 0.0015 M hexazonium pararosaniline solution can protect cryostat sections of unfixed animal tissues from the deleterious effects of aqueous reagents such as buffered solutions used in immunohistochemistry, while preserving specific affinities for antibodies. In the present investigation hexazonium pararosaniline protected lymphoid tissue and striated muscle against the damaging effects of water or saline. The same protection was conferred on unfixed sections treated with dilute nitrous or hydrochloric acid in concentrations similar to those in hexazonium pararosaniline solutions. Model tissues (solutions, gels or films containing gelatin and/or bovine albumin) responded predictably to well known cross-linking (formaldehyde) or coagulant (mercuric chloride) fixatives. Hexazonium pararosaniline solutions prevented the dissolution of protein gels in water only after 9 or more days of contact, during which time considerable swelling occurred. It is concluded that there is no evidence for a “fixative” action of hexazonium pararosaniline. The protective effect on frozen sections of unfixed tissue is attributable probably to the low pH of the solution. 相似文献
10.
Ana I. García-Cervigón Antonio Gazol Virginia Sanz J. Julio Camarero José Miguel Olano 《Perspectives in Plant Ecology, Evolution and Systematics》2013,15(4):226-236
Plant–plant interactions change depending on environmental conditions, shifting from competition to facilitation when the stress is high. In addition to these changes, the relevance of intraspecific compared to interspecific interactions may also shift as abiotic stress does. We inferred intra- and interspecific plant–plant interactions of the cushion plant Hormathophylla spinosa as related to the dominant shrub Juniperus sabina in two sites with contrasting abiotic conditions (a slope with high-stress conditions vs. a valley bottom with milder conditions) in a Mediterranean high mountain. Specifically, we studied the spatial patterns and several variables related to plant performance (plant size and form, non-structural carbohydrate – NSC – concentrations and radial growth) of H. spinosa.The spatial pattern varied depending on site conditions. H. spinosa plants were positively associated with juniper in the high-stress slope site, probably through higher establishment rates due to the amelioration of soil conditions. In contrast, in the milder valley site H. spinosa establishment occurred mostly in open areas. Age structure, inferred from annual rings, reflected a massive establishment event in the whole study area which occurred 30–50 years ago. Canopy variables and radial growth were density dependent: both were negatively affected by the high density of H. spinosa individuals in the valley, but favoured by junipers on the slope. Interestingly, NSCs showed the opposite pattern, suggesting lower investment in growth by H. spinosa plants in the valley than on the slope.Our results reinforce the strong links existing between intra- and interspecific relationships and the need to include both when studying the influence of abiotic conditions on plant–plant interactions. This approach enabled us to detect that the direction and intensity of plant–plant interactions may shift at different ecological levels. Particularly interesting was the finding that optimal sites at the population level may not necessarily be the sites showing maximum individual performance. 相似文献