Extreme drought events have negative effects on forest diversity and functioning. At the species level, however, these effects are still unclear, as species vary in their response to drought through ...specific functional trait combinations. We used long‐term demographic records of 21,821 trees and extensive databases of traits to understand the responses of 338 tropical dry forests tree species to ENSO2015, the driest event in decades in Northern South America. Functional differences between species were related to the hydraulic safety‐efficiency trade‐off, but unexpectedly, dominant species were characterised by high investment in leaf and wood tissues regardless of their leaf phenological habit. Despite broad functional trait combinations, tree mortality was more widespread in the functional space than tree growth, where less adapted species showed more negative net biomass balances. Our results suggest that if dry conditions increase in this ecosystem, ecological functionality and biomass gain would be reduced.
Extreme drought events have negative effects on forest diversity and functioning. We used long‐term demographic records of 21,821 trees and extensive databases of traits to understand the responses of 338 tropical dry forests tree species to an extreme. Our results indicate that irrespective of the drought adaptations, most trees will be negatively affected under drier scenarios predicted for tropical dry forests.
Abstract
We tested the idea that functional trade‐offs that underlie species tolerance to drought drive shifts in community composition via their effects on demographic processes and subsequently on ...shifts in species' abundance. Using data from 298 tree species from tropical dry forests during the extreme ENSO‐2015, we scaled‐up the effects of trait trade‐offs from individuals to communities. Conservative wood and leaf traits favoured slow tree growth, increased tree survival and positively impacted species abundance and dominance at the community‐level. Safe hydraulic traits, on the other hand, were related to demography but did not affect species abundance and communities. The persistent effects of the conservative–acquisitive trade‐off across organizational levels is promising for generalization and predictability of tree communities. However, the safety–efficient trade‐off showed more intricate effects on performance. Our results demonstrated the complex pathways in which traits scale up to communities, highlighting the importance of considering a wide range of traits and performance processes.
Seasonally dry tropical forests are distributed across Latin America and the Caribbean and are highly threatened, with less than 10% of their original extent remaining in many countries. Using 835 ...inventories covering 4660 species of woody plants, we show marked floristic turnover among inventories and regions, which may be higher than in other neotropical biomes, such as savanna. Such high floristic turnover indicates that numerous conservation areas across many countries will be needed to protect the full diversity of tropical dry forests. Our results provide a scientific framework within which national decision-makers can contextuaiize the floristic significance of their dry forest at a regional and continental scale.
We present a first study of the diversity and community composition of lichens in seasonally dry tropical forest (DTF) remnants in the Atlántico department, Colombia. Lichens were sampled in two of ...the three protected areas of the department: Distrito de Manejo Integrado (DMI) Luriza and Reserva Forestal Protectora (RFP) El Palomar. The inventory revealed 61 species, including four new to science: Fissurina linoana Lücking, Moncada & G. Rodr. sp. nov., Graphis lurizana Lücking, Moncada & Celis sp. nov., G. mokanarum Lücking, Moncada & M.C. Martínez sp. nov., and Phaeographis galeanoae Lücking, Moncada & B. Salgado-N. sp. nov. Arthonia erupta and Coenogonium saepincola are new to South America, whereas thirteen species are recorded for Colombia for the first time. Further 37 species are new records for Atlántico, raising the total of species known from the department from 27 to 84. With 42 species at Luriza and 31 at El Palomar, species richness was comparable to that of other DTF sites in the Neotropics. Overlap in species composition between the two sites was remarkably low, with only twelve shared species (20 %), indicating a high level of heterogeneity. Biogeographical affinities lie with Central American DTF, which is in line with those of woody plants. These results underline the importance of the remaining fragments of DTF in Colombia in conserving partially unknown biodiversity and the necessity for their continuing conservation.
Presentamos un primer estudio de la diversidad y composición de comunidades de líquenes en remanentes de bosque seco tropical (bs-T) en el departamento de Atlántico, Colombia. Se muestrearon líquenes en dos de las tres áreas protegidas del departamento: Distrito de Manejo Integrado (DMI) Luriza y Reserva Forestal Protectora (RFP) El Palomar. El inventario registró 61 especies, incluyendo cuatro especies nuevas para la ciencia: Fissurina linoana Lücking, Moncada & G. Rodr. sp. nov., Graphis lurizana Lücking, Moncada & Celis sp. nov., Graphis mokanarum Lücking, Moncada & M.C. Martínez sp. nov. y Phaeographis galeanoae Lücking, Moncada & B. Salgado-N. sp. nov. Arthonia erupta y Coenogonium saepincola son nuevos registros para América del Sur, mientras que trece especies son reportadas por primera vez para Colombia. Unas 37 especies adicionales son nuevos reportes para Atlántico, incrementando el total de especies conocidas para el departamento de 27 a 84. Con 42 especies en Luriza y 31 en El Palomar, la riqueza de especies fue comparable con la de otros sitios de bs-T en el Neotrópico. El traslape en la composición de especies entre los dos sitios es bajo, con solamente doce (20 %) compartidas, indicando un alto nivel de heterogeneidad. Las afinidades biogeográficas son mayores con los bs-T de Centroamérica, lo que coincide con las de plantas leñosas. Estos resultados enfatizan la importancia de los remanentes de bs-T en Colombia para la conservación de una biodiversidad poco conocida.
Tropical dry forests (TDF) are known to be resource‐limited due to a marked seasonality in precipitation. However, TDF are also shaped by factors such as solar radiation, wind speed, soil fertility, ...and land‐cover transformation. Together, these factors may determine different gradients of environmental harshness that are likely to drive changes in plant community attributes. Here, we evaluated the effects of environmental harshness on plant community diversity and structure of Colombian TDF, based on floristic and environmental data from 15 1‐ha permanent plots. We also analyzed these effects on legumes species only (including both deciduous and non‐deciduous species), deciduous species only (including both legumes and non‐legumes species), and on the whole community excluding either legumes or deciduous separately. Drier conditions and higher land‐cover transformation had the strongest negative effects on species diversity, basal area (BA), and canopy height. Soil fertility, on the contrary, did not have a significant effect on any of the evaluated response variables. Interestingly, legumes maintained their diversity and BA along the climatic gradient, while deciduous species were negatively affected by drier conditions and by an increase in secondary vegetation at the landscape level. Our results suggest that although TDF are limited by water availability, land‐cover transformation strongly increases environmental harshness. Yet, both legumes and deciduous species were differentially impacted by climatic and land transformation variables. Thus, to better understand TDF plant community attributes, it is necessary to consider these gradients and to disentangle their effects on different plant functional groups.
in Spanish is available with online material.
Resumen
Es ampliamente conocido que los bosques secos tropicales (BST) tienen fuertes limitaciones de recursos derivadas de estacionalidad de la precipitación. Sin embargo, otros factores como la radiación solar, la velocidad del viento, la fertilidad de los suelos y la transformación de las coberturas también dan forma a las condiciones ambientales restrictivas de este ecosistema. En conjunto, estos factores determinan la dureza ambiental que rige el BST y probablemente explican los cambios en los atributos comunitarios de las plantas a lo largo de gradientes. Evaluamos los efectos de la dureza ambiental sobre la diversidad de plantas y atributos estructurales del BST con base en datos florísticos y ambientales para 15 parcelas permanentes de 1 ha, para toda la comunidad de plantas, y subgrupos de plantas que incluyeron solo especies de leguminas y solo caducifolias por separado. Las condiciones secas y coberturas altamente transformadas tuvieron los efectos negativos sobre la diversidad de especies, el área basal y la altura del dosel a nivel comunitario, mientras que la fertilidad del suelo no afectó a ninguno de los atributos evaluados. Interesantemente, el grupo de especies leguminosas mantuvieron su diversidad y área basal a lo largo del gradiente de severidad climática, mientras que el grupo de especies de hoja caduca se vio negativamente afectado por las condiciones más secas y el aumento en el área de coberturas secundarias. Nuestros resultados sugieren que, aunque el BST esta claramente limitado por la disponibilidad del agua, la transformación de las coberturas naturales impulsa el aumento de la dureza ambiental en este ecosistema. Donde, las especies de leguminosas y caducifolias se ven afectadas de manera diferente a toda la comunidad de plantas. De tal forma, para un mejor entendimiento de como cambian los atributos comunitarios de las plantas en los BST es necesario tener en cuenta todas las fuentes de variación ambiental, así como, desagregar los efectos particulares para determinados grupos funcionales de plantas.
Plant xylem cells conduct water and mineral nutrients. Although most plant cells are totipotent, xylem cells are unusual and undergo terminal differentiation. Many genes regulating this process are ...well characterized, including the Vascular-related NAC Domain 7 (VND7), MYB46, and MYB83 transcription factors, which are proposed to act in interconnected feedforward loops (FFLs). Less is known regarding the molecular mechanisms underlying the terminal transition to xylem cell differentiation. Here, we generate whole-root and single-cell data, which demonstrate that VND7 initiates sharp switching of root cells to xylem cell identity. Based on these data, we identified 4 candidate VND7 downstream target genes capable of generating this switch. Although MYB46 responds to VND7 induction, it is not among these targets. This system provides an important model to study the emergent properties that may give rise to totipotency relative to terminal differentiation and reveals xylem cell subtypes.
Pediatric dengue and sepsis share clinical and pathophysiologic aspects. Multiple inflammatory and regulatory cytokines, decoy receptors and vascular permeability factors have been implicated in the ...pathogenesis of both diseases. The differential pattern and dynamic of these soluble factors, and the relationship with clinical severity between pediatric dengue and sepsis could offer new diagnosis and therapeutic strategies.
We evaluated the concentration levels of 11 soluble factors with proinflammatory, regulatory and vascular permeability involvement, in plasma from children with dengue or sepsis, both clinically ranging from mild to severe, in the early, late and convalescence phases of the disease.
During early acute infection, children with sepsis exhibited specific higher concentration levels of IL-6, vascular endothelial growth factor (VEGF), and its soluble decoy receptor II (sVEGFR2) and lower concentration levels of IL-10 and the soluble tumor necrosis factor receptor 2 (sTNFR2), in comparison with children with severe dengue. In addition, the circulating amounts of soluble ST2, and VEGF/sVEGFR2 were widely associated with clinical and laboratory indicators of dengue severity, whereas secondary dengue virus infections were characterized by an enhanced cytokine response, relative to primary infections. In severe forms of dengue, or sepsis, the kinetics and the cytokines response during the late and convalescence phases of the disease also differentiate.
Dengue virus infection and septic processes in children are characterized by cytokine responses of a specific magnitude, pattern and kinetics, which are implicated in the pathophysiology and clinical outcome of these diseases.
Abstract
Objective
Examine the relationship between symptoms of anxiety ANX and neurocognitive functions of attention ATT and working memory WM in trauma-exposed Puerto Rican adolescents.
Method
...Secondary data analysis was performed of the study’s sample, “Exploring the relationship between Traumatic Exposure on Neurocognitive Processes and Academic Achievement in a sample of Puerto Rican Youth”. This study’s design is a quantitative within-subjects, correlational-causal transactional non-experimental method. Spanish speaking adolescents who reside in Puerto Rico ages 12–17 were recruited. Without serious mental or motor disorders who self-reported exposure to more than one traumatic event. A non-probabilistic convenience sample (N = 21; M = 13; F = 8; Age: M = 15; SD = 1.6) was recruited from clinics (81%) and schools (19%) in different regions of Puerto Rico. To measure traumatic exposure, the Child and Adolescent Trauma Screen (CATS), which is a 15-item self-report trauma screening, was used. The Generalized Anxiety Disorder Scale-7 (GAD-7), a 7-item self-report assessment used to explore anxiety symptoms. Lastly, cognitive variables ATT and WM, were measured using subtests of the standardized neuropsychological battery, Cognitive Assessment System-2: Español (CAS2:ES).
Results
A Linear Regression analysis revealed that total ANX could explain 18% variability of ATT and 56% of WM and were not statistically significant (p = 0.534, IC 95%; 0.53–1.93; p = 0.245, IC 95%: −2.64-0.75) consecutively.
Conclusion
Preliminary data suggest some variability of WM can be explained by ANX experienced in trauma-exposed Puerto Rican adolescents. Confounding variables of complex trauma may exist. A larger clinical sample, including ANX severity and a control group, is recommended to explore cognitive, learning, and mental health consequences.
Cholestatic liver diseases result in the hepatic retention of bile acids, causing subsequent liver toxicity. Peroxisome proliferator‐activated receptor alpha (PPARα) regulates bile acid metabolism. ...In this retrospective observational study, we assessed the effects of fenofibrate (a PPARα agonist) therapy on bile acid metabolism when given to patients with primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) who have had an incomplete response to Ursodiol monotherapy. When fenofibrate was added to Ursodiol therapy there was a significant reduction and in some cases normalization of serum alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase abnormalities, as well as pro‐inflammatory cytokines. Combination fenofibrate treatment also reduced 7α‐hydroxy‐4‐cholesten‐3‐one (C4), the bile acid precursor, as well as total, primary, and conjugated bile acids. In addition, principal components analysis and heatmap analysis show that bile acid metabolites trended closer to that of healthy control subjects. These favorable effects of fenofibrate on bile acid metabolism may contribute to its beneficial clinical effects in patients with PBC and PSC experiencing a subtherapeutic response to Ursodiol monotherapy.
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