5 research outputs found

    A two-component regulatory system playing a critical role in plant pathogens and endosymbionts is present in Brucella abortus and controls cell invasion and virulence

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    Two mutants showing increased sensitivity to polycations and surfactants were obtained by transposon mutagenesis of virulent Brucella abortus 2308 Nal(r). These mutants showed no obvious in vitro growth defects and produced smooth-type lipopolysaccharides. However, they hardly multiplied or persisted in mouse spleens, displayed reduced invasiveness in macrophages and HeLa cells, lost the ability to inhibit lysosome fusion and were unable to replicate intracellularly. Subsequent DNA analyses identified a two-component regulatory system [Brucella virulence related (Bvr)] with a regulatory (BvrR) and sensory (BvrS) protein. Cloning on bvrR in the BvrR-deficient mutant restored the resistance to polycations and, in part, the invasiveness to polycations and, in part, the invasiveness and the ability to multiply intracellularly. BvrR and BvrS were highly similar (87-89% and 70-80% respectively) to the regulatory and sensory proteins of the chromosomally encoded Rhizobium meliloti Chvl-ExoS and Agrobacterium tumefaciens Chvl-ChvG systems previously shown to be critical for endosymbiosis and pathogenicity in plants. Divergence among the three sensory proteins was located mostly within a periplasmic domain probably involved in stimulus sensing. As B. abortus, R. meliloti and A. tumefaciens are phylogenetically related, these observations suggest that these systems have a common ancestor that has evolved to sense stimuli in plant and animal microbial environments.Dos mutantes que muestran una mayor sensibilidad a los policationes y a los tensioactivos se obtuvieron por mutagénesis de transposones de la Brucella abortus 2308 Nal(r) virulenta. Estos mutantes no mostraron defectos evidentes de crecimiento in vitro y produjeron lipopolisacáridos de tipo suave. Sin embargo, apenas se multiplicaron o persistieron en el bazo de los ratones, mostraron una menor capacidad de invasión en macrófagos y células HeLa, perdieron la capacidad de inhibir la fusión de lisosomas y fueron incapaces de replicarse intracelularmente. Los análisis posteriores del ADN identificaron un sistema regulador de dos componentes [Brucella virulence related (Bvr)] con una proteína reguladora (BvrR) y otra sensorial (BvrS). La clonación en bvrR en el mutante deficiente en BvrR restauró la resistencia a los policationes y, en parte, la capacidad de invasión a los policationes y, en parte, la capacidad de invasión y de multiplicación intracelular. BvrR y BvrS eran muy similares (87-89% y 70-80% respectivamente) a las proteínas reguladoras y sensoriales de los sistemas Rhizobium meliloti Chvl-ExoS y Agrobacterium tumefaciens Chvl-ChvG codificados cromosómicamente, que habían demostrado ser críticos para la endosimbiosis y la patogenicidad en las plantas. La divergencia entre las tres proteínas sensoriales se localizó sobre todo en un dominio periplásmico probablemente implicado en la detección de estímulos. Dado que B. abortus, R. meliloti y A. tumefaciens están filogenéticamente relacionados, estas observaciones sugieren que estos sistemas tienen un ancestro común que ha evolucionado para percibir estímulos en entornos microbianos vegetales y animales.Universidad Nacional, Costa RicaEscuela de Medicina Veterinari

    In COVID-19 health messaging, loss framing increases anxiety with Little-to-No concomitant benefits: Experimental evidence from 84 countries

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    The COVID-19 pandemic (and its aftermath) highlights a critical need to communicate health information effectively to the global public. Given that subtle differences in information framing can have meaningful effects on behavior, behavioral science research highlights a pressing question: Is it more effective to frame COVID-19 health messages in terms of potential losses (e.g., “If you do not practice these steps, you can endanger yourself and others”) or potential gains (e.g., “If you practice these steps, you can protect yourself and others”)? Collecting data in 48 languages from 15,929 participants in 84 countries, we experimentally tested the effects of message framing on COVID-19-related judgments, intentions, and feelings. Loss- (vs. gain-) framed messages increased self-reported anxiety among participants cross-nationally with little-to-no impact on policy attitudes, behavioral intentions, or information seeking relevant to pandemic risks. These results were consistent across 84 countries, three variations of the message framing wording, and 560 data processing and analytic choices. Thus, results provide an empirical answer to a global communication question and highlight the emotional toll of loss-framed messages. Critically, this work demonstrates the importance of considering unintended affective consequences when evaluating nudge-style interventions

    A multi-country test of brief reappraisal interventions on emotions during the COVID-19 pandemic

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    Abstract: The COVID-19 pandemic has increased negative emotions and decreased positive emotions globally. Left unchecked, these emotional changes might have a wide array of adverse impacts. To reduce negative emotions and increase positive emotions, we tested the effectiveness of reappraisal, an emotion-regulation strategy that modifies how one thinks about a situation. Participants from 87 countries and regions (n = 21,644) were randomly assigned to one of two brief reappraisal interventions (reconstrual or repurposing) or one of two control conditions (active or passive). Results revealed that both reappraisal interventions (vesus both control conditions) consistently reduced negative emotions and increased positive emotions across different measures. Reconstrual and repurposing interventions had similar effects. Importantly, planned exploratory analyses indicated that reappraisal interventions did not reduce intentions to practice preventive health behaviours. The findings demonstrate the viability of creating scalable, low-cost interventions for use around the world. Protocol registration: The stage 1 protocol for this Registered Report was accepted in principle on 12 May 2020. The protocol, as accepted by the journal, can be found at https://doi.org/10.6084/m9.figshare.c.4878591.v1 © 2021, The Author(s), under exclusive licence to Springer Nature Limited
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