Capacidad de acumulación de cadmio y cobre, y sus efectos en el desempeño fotosintético en Azolla filiculoides Lam. bajo rizofiltración aumentada

This study evaluated the capacity of Azolla filiculoides to enhance heavy metal accumulation through the addition of different concentrations of cadmium (Cd) and copper (Cu), as ethylenediaminetetraacetic acid (EDTA) complexes, under hydroponic conditions. The physiological effect was determined by Photosynthetic efficiency (Fv/Fm) as an indicator of plant stress, and heavy metal content was measured with flame atomic absorption spectroscopy in the whole plants. The results obtained in rhizofiltration systems did not show an increase in accumulation when Cd-EDTA was added, but the Cu-EDTA increased the accumulation of Cu by plants. Although the Fv/Fm was decreased in all treatments, only the Cd-EDTA complex caused damage to photosystem II (PSII) activity, and that damage was critical. These results coincide with the higher toxicity of cadmium to plants; the quantity of cadmium in the plants, although small, was indeed harmful to them. The correlation analysis for both heavy metals coincides with the assumption that the heavy metals on leaf tissue affected the photosynthetic metabolism. This research makes a new contribution to the field by evaluating EDTA-induced Azolla rhizofiltration in aquatic systems, a departure from the majority of the literature on the topic, which examines EDTA in soil remediation. In future, further study is needed on the interactions of EDTA with other ions and the physiological consequences for different plant species.El presente estudio evaluó la capacidad de Azolla filiculoides de incrementar la acumulación de metales pesados a través de la adición de diferentes concentraciones de cadmio (Cd) y cobre (Cu), como complejos del ácido etilendiaminotetraacético (EDTA), bajo condiciones hidropónicas. Los efectos fisiológicos de la capacidad fotosintética fueron determinados por la eficiencia fotosintética (Fv/Fm) como un indicador de estrés en las plantas, y el contenido de metales pesados en la planta completa, fue medido mediante espectroscopia de absorción atómica. Los resultados obtenidos en los sistemas de rizofiltración no lograron alcanzar un incremento en la acumulación de Cd ante la adición de Cd-EDTA, pero el Cu-EDTA aumentó la acumulación de cobre. Aunque el Fv/Fm fue menor en todos los tratamientos, sólo el complejo Cd-EDTA causó daño en la actividad del PSII, y este resultó crítico. Estos resultados coinciden con la alta toxicidad del cadmio en las plantas, la cantidad de cadmio en las plantas, aunque pequeña, resultó dañina. El análisis de correlación para ambos metales pesados concuerda con el supuesto que los metales pesados en el tejido foliar afectan el metabolismo fotosintético. Esta investigación hace una nueva contribución al área, por cuanto se evalúo la rizofiltración inducida con EDTA utilizando Azolla en sistemas acuáticos, cuando la mayoría de la literatura evalúa la remediación en suelos con EDTA. En el futuro, se necesitan más investigaciones enfocada en la interacción del EDTA con otros iones y las consecuencias fisiológicas en diferentes especies de plantas

Ecos de la academia: Revista de la Facultad de Educación, Ciencia y Tecnología - FECYT Nro 6

Ecos de la academia, Revista de la Facultad de Educación Ciencia y Tecnología es una publicación científica de la Universidad Técnica del Norte, con revisión por pares a doble ciego que publica artículos en idioma español, quichua, portugués e inglés. Se edita con una frecuencia semestral con dos números por año.En ella se divulgan trabajos originales e inéditos generados por los investigadores, docentes y estudiantes de la FECYT, y contribuciones de profesionales de instituciones docentes e investigativas dentro y fuera del país, con calidad, originalidad y relevancia en las áreas de ciencias sociales y tecnología aplicada.Modelos multidimensionales del bienestar en contextos de enseñanza- aprendizaje: una revisión sistemática. Nuevas tendencias para el área académica de la Publicidad en la zona 1 del Ecuador. Propuesta de un curso de escritura académica bajo la base de modelos experienciales. Aproximación al estudio de las emociones. Seguimiento a egresados y graduados para actualizar el perfil de egreso y profesional. Impacto de la Gerencia de Calidad en el clima organizacional en Educación Básica. Comunicación efectiva del gerente educativo orientada al manejo de conflictos en el personal docente. Meritocracia: Democratización o exclusión en el acceso a la educación superior en Ecuador. Asertividad y desempeño académico en estudiantes universitarios. La creatividad en la formación profesional. Aspectos metodológicos en el proceso de enseñanza- aprendizaje de la gimnasia en estudiantes de Educación Física. English Language Learning Interaction through Web 2.0 Technologies. La sistematización de la práctica educativa y su relación con la metodología de la investigación. El ozono y la oxigenación hiperbárica: una vía para mejorar la recuperación en lesiones deportivas. La labor tutorial: Independencia del aprendizaje en el contexto universitario. Motivación hacia la profesión docente en la Enseñanza Secundaria. El uso académico de Facebook y WhatsApp en estudiantes universitarios... La educación superior en Ecuador: situación actual y factores de mejora de la calidad. El Proyecto de Investigación “Imbabura Étnica”

Dormancy-break and germination requirements for seeds of the threatened Austral papaya (Carica chilensis)

Abstract Seed dormancy is one of the most important adaptive mechanisms in plants, optimizing germination, seedling emergence, and establishment to ensure these processes occur when environmental conditions are favorable for plant survival and growth. Endemic to rocky environments of the southern Atacama Desert, the Austral papaya (Carica chilensis) is the papaya species with the southernmost distribution within the Caricaceae, thriving in the most extreme environmental conditions. This threatened plant exhibits low natural regeneration, primarily attributed to low germination, yet no information regarding seed dormancy release is available. In this study, we investigated the dormancy-break and germination requirements of C. chilensis. We hypothesized that if C. chilensis seeds exhibit physiological dormancy, then seeds with reduced moisture content and those treated with chemicals or growth hormones would exhibit higher germination percentages and faster germination than control seeds akin to other members of Caricacea. Our results confirmed this prediction and revealed that ultra-drying (< 3% moisture content) and treating seeds with sulfuric acid, gibberellic acid, or potassium nitrate are the most effective methods for germinating C. chilensis. Consequently, we suggest using these treatments to propagate this threatened papaya species

Data from: A hyper arid environment shapes an inverse pattern of the fast–slow plant economics spectrum for above-, but not belowground resource acquisition strategies

1. The fast–slow plant economics spectrum predicts that because of evolutionary and biophysical constraints, different plant organs must be coordinated to converge in a unique ecological strategy within a continuum that shifts from fast to slow resource acquisition and conservation. Therefore, along a gradient of aridity, taxa with different strategies will be expected to be successful because selection pressures for slow resource acquisition become stronger as the environment becomes drier. In extremely arid and seasonal environments, however, a slow strategy may become disadvantageous because slow traits are costly to maintain. Additionally, as the availability of water decreases, selection pressures increase, reducing the variation in ecological strategies. 2. Using shrub assemblages along an aridity gradient in the Atacama Desert, we test the hypothesis that selection pressures imposed by hyper aridity act simultaneously on the variation and coordination of trait attributes, leading to an inverse pattern in the fast – slow plant economics spectrum, where strategies shift from slow to fast as the environment becomes drier. 3. We established 20 to 22 plots at each of four sites along the gradient to estimate plant community structure and functional variation. For all species recorded we quantified a set of leaf, stem and, root traits. 4. Results revealed an inverse pattern of the fast–slow economics spectrum for leaf and stem traits, but not for root traits; that is, as aridity further increased, aboveground traits exhibited a shift from a slow to a fast strategy with some level of coordination. Belowground traits, however, did not shift accordingly with our prediction, rather they showed more complex pattern of shift and coordination with aboveground traits along the gradient. We also found that trait variation showed an idiosyncratic pattern of variation along the gradient, indicating that ecological strategies are driven by local processes within sites. 5. Synthesis: Our results increase our understanding of the fast–slow plant economics spectrum by showing that environmental gradients, as well as local process can simultaneously shape different below- and above-ground resource acquisition strategies in extremely poor resource environments

Risk of COVID-19 after natural infection or vaccinationResearch in context

Background: While vaccines have established utility against COVID-19, phase 3 efficacy studies have generally not comprehensively evaluated protection provided by previous infection or hybrid immunity (previous infection plus vaccination). Individual patient data from US government-supported harmonized vaccine trials provide an unprecedented sample population to address this issue. We characterized the protective efficacy of previous SARS-CoV-2 infection and hybrid immunity against COVID-19 early in the pandemic over three-to six-month follow-up and compared with vaccine-associated protection. Methods: In this post-hoc cross-protocol analysis of the Moderna, AstraZeneca, Janssen, and Novavax COVID-19 vaccine clinical trials, we allocated participants into four groups based on previous-infection status at enrolment and treatment: no previous infection/placebo; previous infection/placebo; no previous infection/vaccine; and previous infection/vaccine. The main outcome was RT-PCR-confirmed COVID-19 >7–15 days (per original protocols) after final study injection. We calculated crude and adjusted efficacy measures. Findings: Previous infection/placebo participants had a 92% decreased risk of future COVID-19 compared to no previous infection/placebo participants (overall hazard ratio [HR] ratio: 0.08; 95% CI: 0.05–0.13). Among single-dose Janssen participants, hybrid immunity conferred greater protection than vaccine alone (HR: 0.03; 95% CI: 0.01–0.10). Too few infections were observed to draw statistical inferences comparing hybrid immunity to vaccine alone for other trials. Vaccination, previous infection, and hybrid immunity all provided near-complete protection against severe disease. Interpretation: Previous infection, any hybrid immunity, and two-dose vaccination all provided substantial protection against symptomatic and severe COVID-19 through the early Delta period. Thus, as a surrogate for natural infection, vaccination remains the safest approach to protection. Funding: National Institutes of Health

Risk of COVID-19 after natural infection or vaccinationResearch in context

Summary: Background: While vaccines have established utility against COVID-19, phase 3 efficacy studies have generally not comprehensively evaluated protection provided by previous infection or hybrid immunity (previous infection plus vaccination). Individual patient data from US government-supported harmonized vaccine trials provide an unprecedented sample population to address this issue. We characterized the protective efficacy of previous SARS-CoV-2 infection and hybrid immunity against COVID-19 early in the pandemic over three-to six-month follow-up and compared with vaccine-associated protection. Methods: In this post-hoc cross-protocol analysis of the Moderna, AstraZeneca, Janssen, and Novavax COVID-19 vaccine clinical trials, we allocated participants into four groups based on previous-infection status at enrolment and treatment: no previous infection/placebo; previous infection/placebo; no previous infection/vaccine; and previous infection/vaccine. The main outcome was RT-PCR-confirmed COVID-19 >7–15 days (per original protocols) after final study injection. We calculated crude and adjusted efficacy measures. Findings: Previous infection/placebo participants had a 92% decreased risk of future COVID-19 compared to no previous infection/placebo participants (overall hazard ratio [HR] ratio: 0.08; 95% CI: 0.05–0.13). Among single-dose Janssen participants, hybrid immunity conferred greater protection than vaccine alone (HR: 0.03; 95% CI: 0.01–0.10). Too few infections were observed to draw statistical inferences comparing hybrid immunity to vaccine alone for other trials. Vaccination, previous infection, and hybrid immunity all provided near-complete protection against severe disease. Interpretation: Previous infection, any hybrid immunity, and two-dose vaccination all provided substantial protection against symptomatic and severe COVID-19 through the early Delta period. Thus, as a surrogate for natural infection, vaccination remains the safest approach to protection. Funding: National Institutes of Health