In evergreen tropical forests, the extent, magnitude, and controls on photosynthetic seasonality are poorly resolved and inadequately represented in Earth system models. Combining camera observations ...with ecosystem carbon dioxide fluxes at forests across rainfall gradients in Amazônia, we show that aggregate canopy phenology, not seasonality of climate drivers, is the primary cause of photosynthetic seasonality in these forests. Specifically, synchronization of new leaf growth with dry season litterfall shifts canopy composition toward younger, more light-use efficient leaves, explaining large seasonal increases (~27%) in ecosystem photosynthesis. Coordinated leaf development and demography thus reconcile seemingly disparate observations at different scales and indicate that accounting for leaf-level phenology is critical for accurately simulating ecosystem-scale responses to climate change.
Leishmania infantum (syn. L. chagasi) is the causative agent of visceral leishmaniasis (VL) in the New World (NW) with endemic regions extending from southern USA to northern Argentina. The two ...hypotheses about the origin of VL in the NW suggest (1) recent importation of L. infantum from the Old World (OW), or (2) an indigenous origin and a distinct taxonomic rank for the NW parasite. Multilocus microsatellite typing was applied in a survey of 98 L. infantum isolates from different NW foci. The microsatellite profiles obtained were compared to those of 308 L. infantum and 20 L. donovani strains from OW countries previously assigned to well-defined populations. Two main populations were identified for both NW and OW L. infantum. Most of the NW strains belonged to population 1, which corresponded to the OW MON-1 population. However, the NW population was much more homogeneous. A second, more heterogeneous, population comprised most Caribbean strains and corresponded to the OW non-MON-1 population. All Brazilian L. infantum strains belonged to population 1, although they represented 61% of the sample and originated from 9 states. Population analysis including the OW L. infantum populations indicated that the NW strains were more similar to MON-1 and non-MON-1 sub-populations of L. infantum from southwest Europe, than to any other OW sub-population. Moreover, similarity between NW and Southwest European L. infantum was higher than between OW L. infantum from distinct parts of the Mediterranean region, Middle East and Central Asia. No correlation was found between NW L. infantum genotypes and clinical picture or host background. This study represents the first continent-wide analysis of NW L. infantum population structure. It confirmed that the agent of VL in the NW is L. infantum and that the parasite has been recently imported multiple times to the NW from southwest Europe.
Here, an alternative route to successfully synthesize polystyrene‐block‐poly(methyl methacrylate) (PS‐b‐PMMA) is reported. Steglich esterification was used as an effective, metal free approach for ...coupling carboxylic terminated PS and the hydroxyl end‐functionalized PMMA chains obtained by nitroxide‐mediated polymerization and atom transfer radical polymerization, respectively. α‐Functionalization was obtained using 4,4′‐azobis(4‐cyanovaleric acid) and 2,2,2‐tribromoethanol as initiators. The synthesis of PS‐b‐PMMA was confirmed by gel permeation chromatography and nuclear magnetic resonance (NMR), while the dependence of the diffusion coefficients of the polymers (PS, PMMA, PS/PMMA blend, and PS‐b‐PMMA) with their corresponding molecular weights was discussed based on the results of atomic force microscopy‐based infrared spectroscopy, differential scanning calorimetry, and spectra of diffusion‐ordered NMR spectroscopy. Differently from PS‐b‐PMMA, a partial segregation was observed for the PS/PMMA blend, affecting its thermal behavior and diffusion coefficient. The study here presented provides an easier and efficient strategy for the synthesis of PS‐b‐PMMA and new insights into the diffusion of polymers.
Polystyrene‐block‐poly(methyl methacrylate) (PS‐b‐PMMA) is synthesized via Steglich esterification, which links the carboxylic terminated PS and the hydroxyl end‐functionalized PMMA chains. It is also demonstrated a correlation between diffusion coefficient of the polymers and their corresponding molecular weight.
This paper reports the study on the synthesis of poly(ε-caprolactone)PCL by ring-opening polymerization (ROP) of ε-caprolactone (CL) monomer with focus on mathematic developing of the growth ...mechanisms of polymer chain. Kinetics and mathematical modeling of ROP of CL was carried out to replicate the different experimental conditions. The computational results of conversion and molecular weight of the polymer were found to be comparable with the experimental results of nuclear magnetic resonance (NMR) spectroscopy and showed that the polymerization is highly dependent on the moisture (ROH). Moreover, parametric studies have shown how the concentrations of octanoic acid and catalyst affect the conversion and molecular weight of the polymer. The study here presented provides further understanding of synthesis of PCL, reporting mathematical models of PCL synthesis which can be used for predicting the characteristic of this biocompatible and biodegradable polymer.
Cardiovascular disease (CVD) has a disproportionate effect on mortality among the poorest people. We assessed the impact on CVD and all-cause mortality of the world's largest conditional cash ...transfer, Brazil's Bolsa Família Programme (BFP).
We linked administrative data from the 100 Million Brazilian Cohort with BFP receipt and national mortality data. We followed individuals who applied for BFP between 1 January 2011 and 31 December 2015, until 31 December 2015. We used marginal structural models to estimate the effect of BFP on all-age and premature (30-69 years) CVD and all-cause mortality. We conducted stratified analyses by levels of material deprivation and access to healthcare. We checked the robustness of our findings by restricting the analysis to municipalities with better mortality data and by using alternative statistical methods.
We studied 17 981 582 individuals, of whom 4 855 324 were aged 30-69 years. Three-quarters (76.2%) received BFP, with a mean follow-up post-award of 2.6 years. We detected 106 807 deaths by all causes, of which 60 893 were premature; and 23 389 CVD deaths, of which 15 292 were premature. BFP was associated with reductions in premature all-cause mortality hazard ratio (HR) = 0.96, 95% CI = 0.94-0.98, premature CVD (HR = 0.96, 95% CI = 0.92-1.00) and all-age CVD (HR = 0.96, 95% CI = 0.93-1.00) but not all-age all-cause mortality (HR = 1.00, 95% CI = 0.98-1.02). In stratified and robustness analyses, BFP was consistently associated with mortality reductions for individuals living in the two most deprived quintiles.
BFP appears to have a small to null effect on premature CVD and all-cause mortality in the short term; the long-term impact remains unknown.
Conditional Cash Transfer Programs have been developed in Latin America in response to poverty and marked social inequalities on the continent. In Brazil, the Bolsa Familia Program (BFP) was ...implemented to alleviate poverty and improve living conditions, health, and education for socioeconomically vulnerable populations. However, the effect of this intervention on maternal and child health is not well understood.
We will evaluate the effect of BFP on maternal and child outcomes: 1. Birth weight; 2. Preterm birth; 3. Maternal mortality; and 4. Child growth. Dynamic retrospective cohort data from the 100 Million Brazilian Cohort (2001 to 2015) will be linked to three different databases: Live Birth Information System (2004 to 2015); Mortality Information System (2011 to 2015); and Food and Nutritional Surveillance System (2008 to 2017). The definition of exposure to the BFP varies according to the outcome studied. Those who never received the benefit until the outcome or until the end of the follow-up will be defined as not exposed. The effects of BFP on maternal and child outcomes will be estimated by a combination of propensity score-based methods and weighted logistic regressions. The analyses will be further stratified to reflect changes in the benefit entitlement before and after 2012.
Harnessing a large linked administrative cohort allows us to assess the effect of the BFP on maternal and child health, while considering a wide range of explanatory and confounding variables.
Passive biomonitoring was applied in four Atlantic forest plots in southeast Brazil, affected by different levels of trace metal pollution (OP site located in Minas Gerais State and PEFI, PP and STG ...located in São Paulo State). Native tree species were selected as biomonitors according to their abundance in each plot and successional classification. Current trace metal concentrations in total suspended particles, leaves of non-pioneer (NPi) and pioneer (Pi) species, topsoil (0–20 cm) and litter and concentration ratios at the plant/soil interface were analyzed to verify the atmosphere-plant-soil interactions, basal concentrations, spatial variations and metal accumulation at the ecosystem level. Redundant analysis helped to identify similar characteristics of metal concentrations in PP and PEFI, which can be influenced by the high concentrations of elements related to anthropogenic inputs. Analysis of variance and multivariate statistics indicated that the trees of OP presented higher concentrations of Cr, Fe, Mn and Ni than those in the other sites. High enrichment of Cd, Fe, Ni in non-pioneer plants indicated that the PP forest (initially considered as the least polluted) has still been affected by metal pollution. Soil collected in STG was enriched by all elements, however these elements were low available for plant uptake. Metal deposited in leaves and litter was an important sink for soil cycling, nevertheless, these metals are not bioavailable in most cases. Non-pioneer tree species revealed to be more appropriate than pioneer species to indicate the current panorama of the contamination and bioavailability levels of trace metals in the tree community-litter-soil interface of the Atlantic forest remnants included in this study.
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•Non-pioneer and pioneer species were selected for biomonitoring metals in four Atlantic Forest plots.•Metals concentrations in leaves, soil and litter and concentration ratios were analyzed.•Soil chemistry and litter in decomposition influenced bioavailability of metals in the forest plots.•Non-pioneer species were more appropriate than pioneers to indicate bioavailability levels of metals.•Cu, Ni and Zn concentrations helped to classify successional stages of rainforest species.
Non-pioneer native tree species of Atlantic Forest, can indicate the current panorama of trace metals contamination in southeast Brazil.
Seasonal dynamics in the vertical distribution of leaf area index (LAI) may impact the seasonality of forest productivity in Amazonian forests. However, until recently, fine-scale observations ...critical to revealing ecological mechanisms underlying these changes have been lacking.
To investigate fine-scale variation in leaf area with seasonality and drought we conducted monthly ground-based LiDAR surveys over 4 yr at an Amazon forest site. We analysed temporal changes in vertically structured LAI along axes of both canopy height and light environments.
Upper canopy LAI increased during the dry season, whereas lower canopy LAI decreased. The low canopy decrease was driven by highly illuminated leaves of smaller trees in gaps. By contrast, understory LAI increased concurrently with the upper canopy. Hence, tree phenological strategies were stratified by height and light environments. Trends were amplified during a 2015–2016 severe El Niño drought.
Leaf area low in the canopy exhibited behaviour consistent with water limitation. Leaf loss from short trees in high light during drought may be associated with strategies to tolerate limited access to deep soil water and stressful leaf environments. Vertically and environmentally structured phenological processes suggest a critical role of canopy structural heterogeneity in seasonal changes in Amazon ecosystem function.
•Cellular kinases can be employed as therapeutic targets to treat viral infections, by means of small molecule inhibitors.•MEK1/2 inhibitor U0126 impairs the replication of Yellow fever virus (YFV) ...and other flaviviruses in vitro.•U0126 reduces YFV genome replication, protein expression, and morphogenesis.•In vivo replication of YFV was also reduced by the treatment with U0126.
Exploiting the inhibition of host signaling pathways aiming for discovery of potential antiflaviviral compounds is clearly a beneficial strategy for the control of life-threatening diseases caused by flaviviruses. Here we describe the antiviral activity of the MEK1/2 inhibitor U0126 against Yellow fever virus 17D vaccine strain (YFV-17D). Infection of VERO cells with YFV-17D stimulates ERK1/2 phosphorylation early during infection. Pharmacological inhibition of MEK1/2 through U0126 treatment of VERO cells blockades not only the YFV-stimulated ERK1/2 phosphorylation, but also inhibits YFV replication by ∼99%. U0126 was also effective against dengue virus (DENV-2 and -3) and Saint-Louis encephalitis virus (SLEV). Levels of NS4AB, as detected by immunofluorescence, are diminished upon treatment with the inhibitor, as well as the characteristic endoplasmic reticulum membrane invagination stimulated during the infection. Though not protective, treatment of YFV-infected, adult BALB/c mice with U0126 resulted in significant reduction of virus titers in brains. Collectively, our data suggest the potential targeting of the MEK1/2 kinase as a therapeutic tool against diseases caused by flaviviruses such as yellow fever, adverse events associated with yellow fever vaccination and dengue.
IntroductionWildfires and deforestation potentially have direct effects on multiple health outcomes as well as indirect consequences for climate change. Tropical rainforest areas are characterised by ...high rainfall, humidity and temperature, and they are predominantly found in low-income and middle-income countries. This study aims to synthesise the methods, data and health outcomes reported in scientific papers on wildfires and deforestation in these locations.Methods and analysisWe will carry out a scoping review according to the Joanna Briggs Institute’s (JBI) manual for scoping reviews and the framework proposed by Arksey and O’Malley, and Levac et al. The search for articles was performed on 18 August 2023, in 16 electronic databases using Medical Subject Headings terms and adaptations for each database from database inception. The search for local studies will be complemented by the manual search in the list of references of the studies selected to compose this review. We screened studies written in English, French, Portuguese and Spanish. We included quantitative studies assessing any human disease outcome, hospitalisation and vital statistics in regions of tropical rainforest. We exclude qualitative studies and quantitative studies whose outcomes do not cover those of interest. The text screening was done by two independent reviewers. Subsequently, we will tabulate the data by the origin of the data source used, the methods and the main findings on health impacts of the extracted data. The results will provide descriptive statistics, along with visual representations in diagrams and tables, complemented by narrative summaries as detailed in the JBI guidelines.Ethics and disseminationThe study does not require an ethical review as it is meta-research and uses published, deidentified secondary data sources. The submission of results for publication in a peer-reviewed journal and presentation at scientific and policymakers’ conferences is expected.Study registrationOpen Science Framework (https://osf.io/pnqc7/).
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