Vegetation‐mediated impacts of trends in global radiation on land hydrology: a global sensitivity study

Incident solar radiation has changed in the last 50 years, as an initial dimming trend from 1960 to approximately 1990 was followed by an ongoing brightening period, with concomitant changes in the partitioning between direct and diffuse fractions. Such radiation changes are expected to affect the global water cycle. In this study, we use the Community Land Model (CLM) to perform global offline simulations for the period 1948–2004 and study the effects of solar forcing changes on trends in evapotranspiration and runoff. The modeled components of the hydrologic cycle respond strongly to the imposed radiation changes in several regions, especially in the tropics. Exceptions are regions with soil moisture‐limited evapotranspiration regime, such as the U.S. Great Plains. In Europe and the Eastern US, the imposed 7 W m^?2 solar dimming for 1960–1990 leads to an evapotranspiration reduction of 1.5 W m^?2 or approximately 5% of the mean and an enhancement of runoff by equal percentage. In these regions, the imposed 6 W m^?2 solar brightening leads to a 3 W m^?2 increase of evapotranspiration in 1990–2004, and a runoff reduction of between 7 and 10% of the mean. Additional simulations investigating the impact of higher diffuse radiation fraction during 1960–1990 suggest mostly an increase of evapotranspiration in the tropics of 2.5 W m^?2 (3% of mean) due to increased photosynthesis from shaded leaves, but with smaller opposite effects elsewhere because of lower ground evaporation. The runoff trend resulting from the imposed radiation/aerosols effect is of the same sign and approximate relative magnitude (but larger absolute magnitude) as those calculated, in various studies, for other potential drivers of runoff change such as climate, CO₂, or land use. These results thus strengthen the claim that radiation effects on runoff are not to be neglected. Understanding the impacts of radiation on the water cycle will affect projections of river flow and freshwater availability for human consumption.     

Effects of 24 weeks of progressive resistance training on knee extensors peak torque and fat-free mass in older women

This study examined the effects of resistance training (RT) on knee extensor peak torque (KEPT) and fat-free mass (FFM) in older women. Seventy-eight volunteers (67.1 ± 5.9 years old) underwent 24 weeks of progressive RT (RTG) while 76 (67.4 ± 5.9 years old) were studied as controls (CG). Dominant knee extension peak torque was assessed using an isokinetic dynamometer (Biodex System 3) and FFM measurements were performed by dual-energy x-ray absorptiometry. Muscle strength and FFM were evaluated before and after the intervention in all volunteers. Participants in the RTG trained major muscle groups 3 times per week during 24 weeks. Training load was kept at 60% of 1 repetition maximum in the first 4 weeks, 70% in the following 4 weeks, and 80% in the remaining 16 weeks, with repetitions, respectively, decreasing from 12, 10, and 8. A Split-plot analysis of variance was performed to examine between- and within-group differences, and the level of significance was accepted at p ≤ 0.05. It was observed that the RTG showed significant increases in KEPT (from 89.9 ± 21.8 to 102.8 ± 22.6 N·m; p < 0.05) and FFM (from 36.4 ± 4.0 to 37.1 ± 4.2 kg, p < 0.05). Appendicular FFM was also significantly increased after the intervention period in the RTG (13.9 ± 1.8 to 14.2 ± 1.9 kg, p < 0.05). None of these changes were observed for the CG. Consistent with the literature, it is concluded that a progressive RT program promotes not only increases in muscle strength, as evaluated by an isokinetic dynamometer, but also in FFM as evaluated by the DXA, in elderly women.     

Silver‐induced conformational changes of polypeptides: a CD study

The role of silver ions in various pathologies, as well as their effect on peptide conformation and properties are less understood. Consequently, we synthesized several peptides with various residues in their sequence to investigate silver‐induced conformational changes at various pH values by Circular Dichroism spectroscopy. Uniquely, the glycine‐based, histidine‐containing peptide showed a severe change from a random coil and β‐turn conformation to large α‐helices during silver binding. When comparing the effect of silver ions on the conformation of bradykinin a similar tendency was found. Besides, silver ions reduced the amyloid‐β peptide tendency to aggregation. Our results suggest a specific and protective role for silver ions in brain pathologies, which is related to their high affinity toward physiologically and pharmacologically active peptides. Fourier transform infrared spectroscopy studies as well as the mass spectrometric ones support our conclusions. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.     

DNA strand breaks and base modifications induced by cholesterol hydroperoxides

Cholesterol (Ch) can be oxidized by reactive oxygen species, forming oxidized products such as Ch hydroperoxides (ChOOH). These hydroperoxides can disseminate the peroxidative stress to other cell compartments. In this work, the ability of ChOOH to induce strand breaks and/or base modifications in a plasmid DNA model was evaluated. In addition, HPLC/MS/MS analyses were performed to investigate the formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) after the incubation of 2'-deoxyguanosine (dGuo) with ChOOH and Cu(2+). In the presence of copper ions, ChOOH induced DNA strand breaks in time and concentration-dependent manners. Purine and pyrimidine base modifications were also observed, as assessed respectively by the treatment with Fpg and Endo III repair enzymes. The detection of 8-oxodGuo by HPLC/MS/MS is in agreement with the dGuo oxidation in plasmid DNA. ChOOH-derived DNA damage adds further support to the role of lipid peroxidation in inducing DNA modifications and mutation.     

Emerging Threats and Opportunities for Large‐Scale Ecological Restoration in the Atlantic Forest of Brazil

Over the past 150 years, Brazil has played a pioneering role in developing environmental policies and pursuing forest conservation and ecological restoration of degraded ecosystems. In particular, the Brazilian Forest Act, first drafted in 1934, has been fundamental in reducing deforestation and engaging private land owners in forest restoration initiatives. At the time of writing (December 2010), however, a proposal for major revision of the Brazilian Forest Act is under intense debate in the National Assembly, and we are deeply concerned about the outcome. On the basis of the analysis of detailed vegetation and hydrographic maps, we estimate that the proposed changes may reduce the total amount of potential areas for restoration in the Atlantic Forest by approximately 6 million hectares. As a radically different policy model, we present the Atlantic Forest Restoration Pact (AFRP), which is a group of more than 160 members that represents one of the most important and ambitious ecological restoration programs in the world. The AFRP aims to restore 15 million hectares of degraded lands in the Brazilian Atlantic Forest biome by 2050 and increase the current forest cover of the biome from 17% to at least 30%. We argue that not only should Brazilian lawmakers refrain from revising the existing Forest Law, but also greatly step up investments in the science, business, and practice of ecological restoration throughout the country, including the Atlantic Forest. The AFRP provides a template that could be adapted to other forest biomes in Brazil and to other megadiversity countries around the world.     

Maintenance of syntenic groups between Cathartidae and Gallus gallus indicates symplesiomorphic karyotypes in new world vultures

Similarities between New World and Old World vultures have been interpreted to reflect a close relationship and to suggest the inclusion of both in Accipitridae (Falconiformes). However, deeper analyses indicated that the placement of the New World vultures (cathartids) in this Order is uncertain. Chromosome analysis has shown that cathartids retained a karyotype similar to the putative avian ancestor. In order to verify the occurrence of intrachromosomal rearrangements in cathartids, we hybridized whole chromosome probes of two species (Gallus gallus and Leucopternis albicollis) onto metaphases of Cathartes aura. The results showed that not only were the syntenic groups conserved between Gallus and C. aura, but probably also the general gene order, suggesting that New World vultures share chromosomal symplesiomorphies with most bird lineages.     

Evaluating environmental and geometrical constraints on endemic vertebrates of the semiarid Caatinga (Brazil)

Most hypotheses explaining species diversity are related to the current and/or past environment, but explanations that rely on geometrical constraints, such as the mid-domain effect, have been recently proposed. Under this type of model, more species are expected in the centre of a domain due to the extent of occurrence of the species being constrained by the domain's geometry. Here we evaluated the proportion of the explanatory power of space, the current environment, historical vicariance events and geometric constraints on the richness of the Caatinga's terrestrial endemic vertebrates using a partial regression approach. The current environment had the highest proportion of explanatory power for the variance of the Caatinga's endemic species, in its shared effect, explaining approximately 47%. On the other hand the geometric constraints model (GCM) had the highest proportion in its single explanatory power with 15% of explanatory power. The amount of explanation by GCM changes when analyzing richness of endemics calculated from species with different range sizes. Despite the fact that GCM is the main driver of the Caatinga's endemic species, in its single effect, this does not necessarily indicate that geometric constraints and random dispersal within species ranges drive richness. The GCM model underestimates richness in the centre of the Caatinga, suggesting that other ecological and evolutionary processes may help explain the overall pattern of decreasing richness towards the borders of the biome.