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51.
Elevated CO2 did not affect the hydrological balance of a mature native Eucalyptus woodland 下载免费PDF全文
Teresa E. Gimeno Tim R. McVicar Anthony P. O'Grady David T. Tissue David S. Ellsworth 《Global Change Biology》2018,24(7):3010-3024
Elevated atmospheric CO2 concentration (eCa) might reduce forest water‐use, due to decreased transpiration, following partial stomatal closure, thus enhancing water‐use efficiency and productivity at low water availability. If evapotranspiration (Et) is reduced, it may subsequently increase soil water storage (ΔS) or surface runoff (R) and drainage (Dg), although these could be offset or even reversed by changes in vegetation structure, mainly increased leaf area index (L). To understand the effect of eCa in a water‐limited ecosystem, we tested whether 2 years of eCa (~40% increase) affected the hydrological partitioning in a mature water‐limited Eucalyptus woodland exposed to Free‐Air CO2 Enrichment (FACE). This timeframe allowed us to evaluate whether physiological effects of eCa reduced stand water‐use irrespective of L, which was unaffected by eCa in this timeframe. We hypothesized that eCa would reduce tree‐canopy transpiration (Etree), but excess water from reduced Etree would be lost via increased soil evaporation and understory transpiration (Efloor) with no increase in ΔS, R or Dg. We computed Et, ΔS, R and Dg from measurements of sapflow velocity, L, soil water content (θ), understory micrometeorology, throughfall and stemflow. We found that eCa did not affect Etree, Efloor, ΔS or θ at any depth (to 4.5 m) over the experimental period. We closed the water balance for dry seasons with no differences in the partitioning to R and Dg between Ca levels. Soil temperature and θ were the main drivers of Efloor while vapour pressure deficit‐controlled Etree, though eCa did not significantly affect any of these relationships. Our results suggest that in the short‐term, eCa does not significantly affect ecosystem water‐use at this site. We conclude that water‐savings under eCa mediated by either direct effects on plant transpiration or by indirect effects via changes in L or soil moisture availability are unlikely in water‐limited mature eucalypt woodlands. 相似文献
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Jean-Pascal Tandonnet Elisa Marguerit Sarah J. Cookson Nathalie Ollat 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2018,131(4):903-915
Key message
QTLs were identified for traits assessed on field-grown grafted grapevines. Root number and section had the largest phenotypic variance explained. Genetic control of root and aerial traits was independent.Abstract
Breeding new rootstocks for perennial crops remains challenging, mainly because of the number of desirable traits which have to be combined, these traits include good rooting ability and root development. Consequently, the present study analyzes the genetic architecture of root traits in grapevine. A segregating progeny of 138 F1 genotypes issued from an inter-specific cross between Vitis vinifera cv. Cabernet-Sauvignon × V. riparia cv. Gloire de Montpellier, used as rootstock, was phenotyped in grafted plants grown for 2 years in the field. Seven traits, related to aerial and root development, were quantified. Heritability ranged between 0.44 for aerial biomass to 0.7 for root number. Total root number was related to the number of fine roots, while root biomass was related to the number of coarse roots. Significant quantitative trait loci (QTLs) were identified for all the traits studied with some of them explaining approximately 20% of phenotypic variance. Only a single QTL co-localized for root and aerial biomass. Identified QTLs for aerial-to-root biomass ratio suggest that aerial and root traits are controlled independently. Genes known to be involved in auxin signaling pathways and phosphorus nutrition, whose orthologues were previously shown to regulate root development in Arabidopsis, were located in the confidence intervals of several QTLs. This study opens new perspectives for breeding rootstocks with improved root development capacities.54.
Short‐term carbon cycling responses of a mature eucalypt woodland to gradual stepwise enrichment of atmospheric CO2 concentration 下载免费PDF全文
John E. Drake Catriona A. Macdonald Mark G. Tjoelker Kristine Y. Crous Teresa E. Gimeno Brajesh K. Singh Peter B. Reich Ian C. Anderson David S. Ellsworth 《Global Change Biology》2016,22(1):380-390
Projections of future climate are highly sensitive to uncertainties regarding carbon (C) uptake and storage by terrestrial ecosystems. The Eucalyptus Free‐Air CO2 Enrichment (EucFACE) experiment was established to study the effects of elevated atmospheric CO2 concentrations (eCO2) on a native mature eucalypt woodland with low fertility soils in southeast Australia. In contrast to other FACE experiments, the concentration of CO2 at EucFACE was increased gradually in steps above ambient (+0, 30, 60, 90, 120, and 150 ppm CO2 above ambient of ~400 ppm), with each step lasting approximately 5 weeks. This provided a unique opportunity to study the short‐term (weeks to months) response of C cycle flux components to eCO2 across a range of CO2 concentrations in an intact ecosystem. Soil CO2 efflux (i.e., soil respiration or Rsoil) increased in response to initial enrichment (e.g., +30 and +60 ppm CO2) but did not continue to increase as the CO2 enrichment was stepped up to higher concentrations. Light‐saturated photosynthesis of canopy leaves (Asat) also showed similar stimulation by elevated CO2 at +60 ppm as at +150 ppm CO2. The lack of significant effects of eCO2 on soil moisture, microbial biomass, or activity suggests that the increase in Rsoil likely reflected increased root and rhizosphere respiration rather than increased microbial decomposition of soil organic matter. This rapid increase in Rsoil suggests that under eCO2, additional photosynthate was produced, transported belowground, and respired. The consequences of this increased belowground activity and whether it is sustained through time in mature ecosystems under eCO2 are a priority for future research. 相似文献
55.
Roland Abi Nahed Guillaume Martinez Jessica Escoffier Sandra Yassine Thomas Karaouzène Jean-Pascal Hograindleur John Turk George Kokotos Pierre F. Ray Serge Bottari Gérard Lambeau Sylviane Hennebicq Christophe Arnoult 《The Journal of biological chemistry》2016,291(6):3076-3089
Phospholipase A2 (PLA2) activity has been shown to be involved in the sperm acrosome reaction (AR), but the molecular identity of PLA2 isoforms has remained elusive. Here, we have tested the role of two intracellular (iPLA2β and cytosolic PLA2α) and one secreted (group X) PLA2s in spontaneous and progesterone (P4)-induced AR by using a set of specific inhibitors and knock-out mice. iPLA2β is critical for spontaneous AR, whereas both iPLA2β and group X secreted PLA2 are involved in P4-induced AR. Cytosolic PLA2α is dispensable in both types of AR. P4-induced AR spreads over 30 min in the mouse, and kinetic analyses suggest the presence of different sperm subpopulations, using distinct PLA2 pathways to achieve AR. At low P4 concentration (2 μm), sperm undergoing early AR (0–5 min post-P4) rely on iPLA2β, whereas sperm undergoing late AR (20–30 min post-P4) rely on group X secreted PLA2. Moreover, the role of PLA2s in AR depends on P4 concentration, with the PLA2s being key actors at low physiological P4 concentrations (≤2 μm) but not at higher P4 concentrations (∼10 μm). 相似文献
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Thengarai S. Venkatakrishnan Inhar Imaz Jean-Pascal Sutter 《Inorganica chimica acta》2008,361(12-13):3710-3713
An unprecedented octanuclear aggregate, [{Co(phen)2}6{W(CN)8}2Cl2] · 2Cl, 2, resulted from the assembling of {Co(phen)2Cl2}, 1, and {W(CN)8}4?. Surprisingly, the reaction with the paramagnetic {Nb(CN)8}4? unit did not afford the homologous {Co–Nb} cluster. Instead the latter building unit undergoes dissociation which led to the formation of a mixed-valence [{CoII(phen)2}{CoIII(phen)(CN)4}2], 3. This observation is in contrast to the usual trend that {NbIV(CN)8}4? forms compounds isostructural to that observed for {MoIV(CN)8}4? and {WIV(CN)8}4?. The structures of the compounds 2 and 3 have been established by single crystal X-ray diffraction. Magnetic behaviors for compounds 1–3 are reported. 相似文献
59.
Suárez-Varela MM García-Marcos Alvarez L Kogan MD González AL Gimeno AM Aguinaga Ontoso I Díaz CG Pena AA Aurrecoechea BD Monge RM Quiros AB Garrido JB Canflanca IM Varela AL 《International journal of biometeorology》2008,52(8):833-840
Atopic eczema (AE) is a chronic skin disease. Recent reports indicate that the worldwide prevalence of AE is increasing and
that various environmental factors are implicated in its aetiology. Climatic conditions have been related with AE prevalence,
and Spain has varying climatic conditions. The aim of this study is to document the possible climatic influence on the prevalence
of AE in schoolchildren aged 6–7 years in three different climatic regions in Spain. We conducted a cross-sectional population-based
survey of 28,394 schoolchildren aged 6–7 years from 10 Spanish centres in three different climatic regions. The mean participation
rate was 76.5%. AE prevalence was assessed using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire
and the Spanish Academy of Dermatology criteria used in Spain to diagnose AE. The data, including annual temperature, precipitation,
relative humidity and the annual number of sunny hours per climatic region, were obtained from the Spanish National Institute
of Meteorology. Different AE prevalences were found in all three climatic regions studied: Atlantic, 32.9; Mediterranean 28.3;
and Continental 31.2 per 100 children studied (p < 0.005). AE was positively associated with precipitation and humidity, and was negatively associated with temperature and
the number of sunny hours. The results show that AE is significantly dependent on meteorological conditions. 相似文献
60.
Investigation of the antifouling constituents from the brown alga Sargassum muticum (Yendo) Fensholt
Alexandra Bazes Alla Silkina Philippe Douzenel Fabienne Faÿ Nelly Kervarec Danièle Morin Jean-Pascal Berge Nathalie Bourgougnon 《Journal of applied phycology》2009,21(4):395-403
One of the most promising alternatives to toxic heavy metal-based paints is offered by the development of antifouling coatings
in which the active ingredients are compounds naturally occurring in marine organisms and operating as natural antisettlement
agents. Sessile marine macroalgae are remarkably free from settlement by fouling organisms. They produce a wide variety of
chemically active metabolites in their surroundings, potentially as an aid to protect themselves against other settling organisms.
In this study, a dichloromethane extract from the brown seaweed Sargassum muticum was tested in situ and, after 2 months of immersion, showed less fouling organisms on paints in which the extract was included,
compared to paints containing only copper after 2 months of immersion. No barnacles or mussels have been observed on the test
rack. Identification by NMR and GC/MS of the effective compound revealed the abundance of palmitic acid, a commonly found
fatty acid. Pure palmitic acid showed antibacterial activity at 44 μg mL−1, and also inhibited the growth of the diatom Cylindrotheca closterium at low concentration (EC50 = 45.5 μg mL−1), and the germination of Ulva lactuca spores at 3 μg mL−1. No cytotoxicity was highlighted, which is promising in the aim of the development of an environmentally friendly antifouling
paint. 相似文献