Elevated CO2 did not affect the hydrological balance of a mature native Eucalyptus woodland

Elevated atmospheric CO₂ concentration (eC_a) 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 (E_t) is reduced, it may subsequently increase soil water storage (ΔS) or surface runoff (R) and drainage (D_g), although these could be offset or even reversed by changes in vegetation structure, mainly increased leaf area index (L). To understand the effect of eC_a in a water‐limited ecosystem, we tested whether 2 years of eC_a (~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 eC_a reduced stand water‐use irrespective of L, which was unaffected by eC_a in this timeframe. We hypothesized that eC_a would reduce tree‐canopy transpiration (E_tree), but excess water from reduced E_tree would be lost via increased soil evaporation and understory transpiration (E_floor) with no increase in ΔS, R or D_g. We computed E_t, ΔS, R and D_g from measurements of sapflow velocity, L, soil water content (θ), understory micrometeorology, throughfall and stemflow. We found that eC_a did not affect E_tree, E_floor, 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 D_g between C_a levels. Soil temperature and θ were the main drivers of E_floor while vapour pressure deficit‐controlled E_tree, though eC_a did not significantly affect any of these relationships. Our results suggest that in the short‐term, eC_a does not significantly affect ecosystem water‐use at this site. We conclude that water‐savings under eC_a 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.     

Climate and prevalence of atopic eczema in 6- to 7-year-old school children in Spain. ISAAC PhASE III

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.     

Mixed-model of ANOVA for measurement reproducibility in proteomics

This work is a statistical analysis of reproducibility of a MALDI-TOF mass spectrometry experiment. Its aim is to evaluate measurement variability and compare peak intensities from two types of MALDI-TOF platforms. We compared and commented on the abilities of Principal Component Analysis and mixed-model analysis of variance to evaluate the biological variability and the technical variability of peak intensities in different patients. The properties and hypotheses of both methods are summarized and applied to spectra from plasma of patients with Hodgkin lymphoma. Principal Component Analysis checks rapidly the balance between the two variabilities; however, a mixed-model analysis of variance is necessary to quantify the biological and technical components of the experimental variance as well as their interactions and to split the total variance into between-subjects and within-subject components. The latter method helped to assess the reproducibility of measurements from two MALDI-TOF platforms and to decompose the technical variability according to the experimental design.     

A Lagrangian Identification of the Main Sources of Moisture Affecting Northeastern Brazil during Its Pre-Rainy and Rainy Seasons

This work examines the sources of moisture affecting the semi-arid Brazilian Northeast (NEB) during its pre-rainy and rainy season (JFMAM) through a Lagrangian diagnosis method. The FLEXPART model identifies the humidity contributions to the moisture budget over a region through the continuous computation of changes in the specific humidity along back or forward trajectories up to 10 days period. The numerical experiments were done for the period that spans between 2000 and 2004 and results were aggregated on a monthly basis. Results show that besides a minor local recycling component, the vast majority of moisture reaching NEB area is originated in the south Atlantic basin and that the nearby wet Amazon basin bears almost no impact. Moreover, although the maximum precipitation in the “Poligono das Secas” region (PS) occurs in March and the maximum precipitation associated with air parcels emanating from the South Atlantic towards PS is observed along January to March, the highest moisture contribution from this oceanic region occurs slightly later (April). A dynamical analysis suggests that the maximum precipitation observed in the PS sector does not coincide with the maximum moisture supply probably due to the combined effect of the Walker and Hadley cells in inhibiting the rising motions over the region in the months following April.     

Conjugates of ferrocene with biological compounds. Coordination to gold complexes and antitumoral properties

Several bioconjugates of ferrocene with biological compounds such as aminoacid esters and related species have been prepared by reaction of chlorocarbonyl ferrocene with the corresponding amino acid ester (histidine methyl ester, tryptophan methyl ester, methionine methyl ester and lysine ethyl ester) or histamine or prolinamide in the presence of NEt₃. The reaction of the tryptophan or prolinamide ferrocene conjugates with [Au(acac)(PR₃)] (acac = acetylacetonate) results in the substitution of the proton of the cyclic NH groups by the fragment AuPR₃⁺ affording the complexes [Au(FcCO-tryptophan-OMe)(PR₃)] or [Au(FcCO-prolinamide)(PR₃)] (Fc = ferrocenyl group). The reaction of FcCO-Met-OMe with [Au(OTf)(PR₃)] (OTF = trifluoromethysulfonate) or [Au(C₆F₅)₃(OEt₂)] yields the gold(I) or gold(III) derivatives [Au(FcCO-Met-OMe)(PR₃)]OTf or [Au(C₆F₅)₃(FcCO-Met-OMe)], respectively. Cytotoxicity studies towards several cancer lines such as MCF-7, HeLa or NIE-115 have been performed. The ferrocene bioconjugates show no activity whereas the gold complexes exhibit antiproliferative effect. Preliminary studies of interaction of compounds with cells were carried out with the goal of increasing our knowledge on the mechanism of action of these potential drugs.     

Calculation of theoretical and empirical nutrient N critical loads in the mixed conifer ecosystems of southern California

Edaphic, foliar, and hydrologic forest nutrient status indicators from 15 mixed conifer forest stands in the Sierra Nevada, San Gabriel Mountains, and San Bernardino National Forest were used to estimate empirical or theoretical critical loads (CL) for nitrogen (N) as a nutrient. Soil acidification response to N deposition was also evaluated. Robust empirical relationships were found relating N deposition to plant N uptake (N in foliage), N fertility (litter C/N ratio), and soil acidification. However, no consistent empirical CL were obtained when the thresholds for parameters indicative of N excess from other types of ecosystems were used. Similarly, the highest theoretical CL for nutrient N calculated using the simple mass balance steady state model (estimates ranging from 1.4-8.8 kg N/ha/year) was approximately two times lower than the empirical observations. Further research is needed to derive the thresholds for indicators associated with the impairment of these mixed conifer forests exposed to chronic N deposition within a Mediterranean climate. Further development or parameterization of models for the calculation of theoretical critical loads suitable for these ecosystems will also be an important aspect of future critical loads research.     

Short‐term carbon cycling responses of a mature eucalypt woodland to gradual stepwise enrichment of atmospheric CO2 concentration

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 R_soil) 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 (A_sat) 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 R_soil likely reflected increased root and rhizosphere respiration rather than increased microbial decomposition of soil organic matter. This rapid increase in R_soil suggests that under eCO_2, 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.