ABSTRACT
Introducción: En 2020, surgió la pandemia del COVID-19, causada por el SARS-CoV-2, asociada a mayor morbi-mortalidad impactando las vidas de la población mundial. Objetivo: Determinar conocimientos de vías de transmisión, medidas de prevención y actitudes sobre COVID-19 en estudiantes de 5° y 6° año de la Facultad de Medicina de la Universidad Nacional del Nordeste en los meses de mayo a junio del 2020. Métodos: Se realizó un estudio descriptivo, transversal con los estudiantes de los últimos años de la Carrera de Medicina. El instrumento fue validado por juicio de expertos. Se utilizó un cuestionario prediseñado ad hoc a través de la plataforma Google Forms. Los datos fueron analizados mediante el software Epi Info versión 7. Resultados: Fueron analizadas un total de 153 encuestas (N=153). La edad media fue 24,8 años. El 42% de los estudiantes encuestados refiere informarse de charlas con médicos, el 15% mediante redes sociales, canales de televisión y blogs y un 13% restante lo hace a través de amigos y/o familiares. El 95,4% de la población estudiada tuvo cambios de actitud aumentó la forma de limpiar/desinfectar las superficies y ambientes. El 70% respondió que es a través del aire (Gotas de Flügge), mientras hablan, tosen o estornuda como la vía de contagio más frecuente. El 84,4% menciona encontrarse tranquilo, el 13% está nervioso y preocupado y el 2,6% cansado. Conclusión: Se encuentran conocimientos adecuados y actitudes positivas en la población estudiada.
Introduction: In 2020, the COVID-19 pandemic emerged, caused by SARS-CoV-2, associated with higher morbidity and mortality, impacting the lives of the world population. Objective: Determine knowledge of transmission routes, prevention measures and attitudes about COVID-19 in 5th and 6th year students of the Facultad de Medicina of the Universidad Nacional del Nordeste in the months of May to June 2020. Methods: A descriptive, cross-sectional study was carried out with the students of the last years of the Medicine career. The instrument was validated by expert judgment. A pre-designed ad hoc questionnaire was used through the Google Forms platform. The data were analyzed using Epi Info version 7 software. Results: A total of 153 surveys were analyzed (N = 153). The mean age was 24.8 years. 42% of the students surveyed refer to information about talks with doctors, 15% through social networks, television channels and blogs and the remaining 13% do so through friends and / or family. 95.4% of the population studied had changes in attitude, increasing the way of cleaning / disinfecting surfaces and environments. 70% responded that it is through the air (Flügge Drops), while talking, coughing or sneezing as the most frequent route of infection. 84.4% mention being calm, 13% are nervous and worried and 2.6% tired. Conclusion: Adequate knowledge and positive attitudes are found in the studied population.
ABSTRACT
Abiotic stress has a growing impact on plant growth and agricultural activity worldwide. Specific plant growth promoting rhizobacteria have been reported to stimulate growth and tolerance to abiotic stress in plants, and molecular mechanisms like phytohormone synthesis and 1-aminocyclopropane-1-carboxylate deamination are usual candidates proposed to mediate these bacterial effects. Paraburkholderia phytofirmans PsJN is able to promote growth of several plant hosts, and improve their tolerance to chilling, drought and salinity. This work investigated bacterial determinants involved in PsJN stimulation of growth and salinity tolerance in Arabidopsis thaliana, showing bacteria enable plants to survive long-term salinity treatment, accumulating less sodium within leaf tissues relative to non-inoculated controls. Inactivation of specific bacterial genes encoding ACC deaminase, auxin catabolism, N-acyl-homoserine-lactone production, and flagellin synthesis showed these functions have little influence on bacterial induction of salinity tolerance. Volatile organic compound emission from strain PsJN was shown to reproduce the effects of direct bacterial inoculation of roots, increasing plant growth rate and tolerance to salinity evaluated both in vitro and in soil. Furthermore, early exposure to VOCs from P. phytofirmans was sufficient to stimulate long-term effects observed in Arabidopsis growth in the presence and absence of salinity. Organic compounds were analyzed in the headspace of PsJN cultures, showing production of 2-undecanone, 7-hexanol, 3-methylbutanol and dimethyl disulfide. Exposure of A. thaliana to different quantities of these molecules showed that they are able to influence growth in a wide range of added amounts. Exposure to a blend of the first three compounds was found to mimic the effects of PsJN on both general growth promotion and salinity tolerance. To our knowledge, this is the first report on volatile compound-mediated induction of plant abiotic stress tolerance by a Paraburkholderia species.
ABSTRACT
Modulation of phytohormones homeostasis is one of the proposed mechanisms to explain plant growth promotion induced by beneficial rhizobacteria (PGPR). However, there is still limited knowledge about the molecular signals and pathways underlying these beneficial interactions. Even less is known concerning the interplay between phytohormones in plants inoculated with PGPR. Auxin and ethylene are crucial hormones in the control of plant growth and development, and recent studies report an important and complex crosstalk between them in the regulation of different plant developmental processes. The objective of this work was to study the role of both hormones in the growth promotion of Arabidopsis thaliana plants induced by the well-known PGPR Burkholderia phytofirmans PsJN. For this, the spatiotemporal expression patterns of several genes related to auxin biosynthesis, perception and response and ethylene biosynthesis were studied, finding that most of these genes showed specific transcriptional regulations after inoculation in roots and shoots. PsJN-growth promotion was not observed in Arabidopsis mutants with an impaired ethylene (ein2-1) or auxin (axr1-5) signaling. Even, PsJN did not promote growth in an ethylene overproducer (eto2), indicating that a fine regulation of both hormones signaling and homeostasis is necessary to induce growth of the aerial and root tissues. Auxin polar transport is also involved in growth promotion, since PsJN did not promote primary root growth in the pin2 mutant or under chemical inhibition of transport in wild type plants. Finally, a key role for ethylene biosynthesis was found in the PsJN-mediated increase in root hair number. These results not only give new insights of PGPR regulation of plant growth but also are also useful to understand key aspects of Arabidopsis growth control.
ABSTRACT
Salinity is one of the major limitations for food production worldwide. Improvement of plant salt-stress tolerance using plant-growth promoting rhizobacteria (PGPR) has arisen as a promising strategy to help overcome this limitation. However, the molecular and biochemical mechanisms controlling PGPR/plant interactions under salt-stress remain unclear. The main objective of this study was to obtain new insights into the mechanisms underlying salt-stress tolerance enhancement in the salt-sensitive Arabidopsis thaliana Col-0 plants, when inoculated with the well-known PGPR strain Burkholderia phytofirmans PsJN. To tackle this, different life history traits, together with the spatiotemporal accumulation patterns for key metabolites and salt-stress related transcripts, were analyzed in inoculated plants under short and long-term salt-stress. Inoculated plants displayed faster recovery and increased tolerance after sustained salt-stress. PsJN treatment accelerated the accumulation of proline and transcription of genes related to abscisic acid signaling (Relative to Dessication, RD29A and RD29B), ROS scavenging (Ascorbate Peroxidase 2), and detoxification (Glyoxalase I 7), and down-regulated the expression of Lipoxygenase 2 (related to jasmonic acid biosynthesis). Among the general transcriptional effects of this bacterium, the expression pattern of important ion-homeostasis related genes was altered after short and long-term stress (Arabidopsis K(+) Transporter 1, High-Affinity K(+) Transporter 1, Sodium Hydrogen Exchanger 2, and Arabidopsis Salt Overly Sensitive 1). In all, the faster and stronger molecular changes induced by the inoculation suggest a PsJN-priming effect, which may explain the observed tolerance after short-term and sustained salt-stress in plants. This study provides novel information about possible mechanisms involved in salt-stress tolerance induced by PGPR in plants, showing that certain changes are maintained over time. This opens up new venues to study these relevant biological associations, as well as new approaches to a better understanding of the spatiotemporal mechanisms involved in stress tolerance in plants.
