Examinando por Autor "Valdés, Iván"

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    How Were Modified the Human Anatomy Study Habits During and After Confinement By the COVID-19 Pandemic?
    (Universidad de la Frontera, 2022-12) Sánchez-Ramírez, Celso; Alarcón, Eduardo; Bravo, Leonardo; Paredes, Paula; Nova, Pablo; Iturra-González, Alejandro; Valdés, Iván; Ortiz, Ana
    During 2020 and 2021 the anatomy subject was developed by online classes. In 2022, face-to-face teaching activities were resumed. The objective was to compare the autonomous study habits of two student generations that coursed the Human Anatomy subject in online and face-to-face mode. Two groups of students were asked to fill-out an online questionnaire. Online Generation (OL) (n=185) and Face-to-face Generation (FF) (n=154). The difference between both groups was the learning activities. OL received only online classes, and FF received theoretical classes and laboratory activities in face-to-face sessions. The most of OL subjects had greater clarity about the contents (71.9 %) and the depth (50.8 %) that they should study them, in contrast with FF (58.4 %, p = 0.0124 and 24.7 %, p < 0.0001 respectively). In OL, 47 % spent more than 4 hours weekly studying human anatomy, whereas in FF 68.2 % (p<0.0001). In both groups, the most important resource was the Video Recorded Classes (90.8 % in OL, and 83.1 % in FF). For OL, the three priority resources were exclusively electronic: 1) Video Recorded Classes, 2) Apps on smartphone or tablets, and 3) Apps on laptop or computer. FF generation prioritized: 1) Video Recorded Classes, 2) Anatomy Atlas, and 3) Class Slides. During the COVID-19 pandemic, the students that received only online classes were able to plain their study time in a better way than whose were in face-to-face classes. However, they spent less time to study the topics. In addition, it was possible to determine that students prefer digital resources (video classes recorded and apps in smartphone or computer) over traditional resources such as textbook and anatomy atlas. It proposes to consider these results in the Human Anatomy subjects design, in virtual or face-to-face mode. © 2022, Universidad de la Frontera. All rights reserved.
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    Participation of two sRNA RyhB homologs from the fish pathogen Yersinia ruckeri in bacterial physiology
    (Microbiological Research, Volume 242January 2021 Article number 126629, 2021) Acuña, Lillian G.; Barros, M. José; Montt, Fernanda; Peñaloza, Diego; Núñez, Paula; Valdés, Iván; Gil, Fernando; Fuentes, Juan A.; Calderón, Iván L.
    Small noncoding RNAs (sRNAs) are important regulators of gene expression and physiology in bacteria. RyhB is an iron-responsive sRNA well characterized in Escherichia coli and conserved in other Enterobacteriaceae. In this study, we identified and characterized two RyhB homologs (named RyhB-1 and RyhB-2) in the fish pathogen Yersinia ruckeri. We found that, as in other Enterobacteriaceae, both RyhB-1 and RyhB-2 are induced under iron starvation, repressed by the Fur regulator, and depend on Hfq for stability. Despite these similarities in expression, the mutant strains of Y. ruckeri lacking RyhB-1 (ΔryhB-1) or RyhB-2 (ΔryhB-2) exhibited differential phenotypes. In comparison with the wild type, the ΔryhB-1 strain showed a hypermotile phenotype, reduced biofilm formation, increased replication rate, faster growth, and increased ATP levels in bacterial cultures. By contrast, in salmon cell cultures, the ΔryhB-1 strain exhibited an increased survival. On the other hand, the ΔryhB-2 strain was non-motile and showed augmented biofilm formation as compared to the wild type. The expression of a subset of RyhB conserved targets, selected from different bacterial species, was analyzed by quantitative RT-PCR in wild type, ΔryhB-1, ΔryhB-2, and ΔryhB-1 ΔryhB-2 strains cultured in iron-depleted media. RyhB-1 negatively affected the expression of most analyzed genes (sodB, acnA, sdhC, bfr, fliF, among others), whose functions are related to metabolism and motility, involving iron-containing proteins. Among the genes analyzed, only sdhC and bfr appeared as targets for RyhB-2. Taken together, these results indicate that Y. ruckeri RyhB homologs participate in the modulation of the bacterial physiology with non-redundant roles. © 2020 Elsevier GmbH