Repositorio UTN
El Repositorio Institucional de la Universidad Técnica Nacional (UTN) es la memoria institucional, conserva el patrimonio documental universitario, así como ofrece un espacio que invita al intercambio de saberes. Asimismo, es una herramienta que permite reunir, almacenar, preservar y difundir la producción científica y académica de esta institución, producto de una cultura investigativa de innovación, desarrollo y transferencia que busca aportar en la construcción de un mundo más inclusivo, equitativo y próspero para todas las personas. Los libros, artículos científicos y académicos, informes, documentos técnicos, trabajos finales de graduación, material didáctico y multimedia, registros, software, entre otros, serán parte del canal de información que se habilita tanto para la población de la UTN como para las diversas audiencias existentes. De tal manera que se visualiza como una puerta de acceso abierto para interconectar la institución con el mundo, en la cual se comparte conocimiento e información en formato digital.
Recent Submissions
An Action Research for Implementing Metacognitive Strategies for Increasing EFL Beginner Learners' Awareness on English Structure in Oral Production in a group of 14 students from Ingles Integrado III at Universidad Técnica Nacional Sede Regional de Guanacaste
(2021) Imer Alejandro Salazar Aguirre
This final project proposes the action research for implementing metacognitive strategies for a group of 14 EFL beginner students in order to improve their speaking skills from Integrated English III at the Universidad Técnica Nacional Sede Regional de Guanacaste, Costa Rica.
Learning English as a second language today has become a necessary tool to communicate, over the years English has been involved in accelerated growth. In terms of the process of acquiring a second language, it is important that teachers, as well as institutions, collect valuable information to improve cognitive and metacognitive strategies as well as the methodologies that are required to be applied in classes in order to help learners.
Studies have proven that all students learn in different ways, that is, all students have unique colours that identify them as learners, so all students have different characteristics about their cognition, metacognition, psychological, affective and physically in which those differences influence the learning of each individual.
Application of PCR-based diagnostic tools that target Enterocytozoon hepatopenaei for the molecular detection of a Vittaforma-like microsporidium that infects Penaeus vannamei from Costa Rica
(2023) Nelson Pena-Navarro; Antonio López Carvallo; Brandon Chacón Pérez; Roberto Cruz Flores
Several PCR methodologies are available for the detection of Enterocytozoon hepatopenaei (EHP) that target the SSU rRNA gene. However, these methodologies are reported as unsuitable for the detection of EHP due to specificity issues. Here, we report the applicability of two commonly used SSU rRNA methodologies for the detection of additional microsporidia from the genus Vittaforma that is present in cultured Penaeus vannamei from Costa Rica. The molecular detection of DNA of the novel microsporidia can only be achieved using SSU rRNA targeting methodologies and does not cross-react with the highly specific spore wall protein gene PCR detection method.
Variabilidad genética del pez Lutjanus guttatus (Perciformes: Lutjanidae) mediante el uso de microsatélites en Costa Rica
(2023) Alejandra Murillo-Rios; Silvia Ramirez-Flores; Juan Esteban Barquero-Chanto; Nelson Peña-Navarro; Ricardo Pérez-Enríquez
Introducción: El pargo mancha es un pez marino de alto consumo e interés comercial en Costa Rica que está
sometido a una fuerte presión pesquera, la cual puede afectar la diversidad genética y generar problemas por
depresión endogámica. Objetivo: Evaluar el estado genético de la población de Lutjanus guttatus mediante el uso microsatélites.
Métodos: Se recolectaron muestras entre el 2018 y 2019 y se estudiaron 44 individuos de cada una de las localidades
del Golfo de Nicoya y Golfo Dulce. Se realizó la extracción de ADN y la amplificación de diez loci con
microsatélites mediante PCR, para la determinación del genotipo, análisis de diversidad genética y estructura
poblacional. Resultados: Los parámetros de diversidad indican un elevado polimorfismo asociado con un alto número de
alelos obtenidos por locus, pero con bajos niveles de heterocigosidad observada en comparación con la esperada
(Ho= 0.774 y 0.800 y He= 0.948 y 0.954 para Golfo de Nicoya y Golfo Dulce, respectivamente). No hay evidencia
suficiente para decir que las dos poblaciones son distintas (FST= 0.00264, P > 0.05). La desviación del
Equilibrio de Hardy-Weinberg indica la posible mezcla de organismos de origen distinto a los del medio silvestre.
Conclusiones: L. guttatus tiene niveles altos de diversidad genética, no hay evidencia de diferenciación en subpoblaciones
genéticas, lo que en manejo pesquerías se considera una sola población panmíctica. La posible mezcla
de individuos de origen distinto al silvestre sugiere la presencia de organismos de un programa de repoblación o
de cultivos comerciales en la región. El uso de marcadores genéticos se recomienda para el monitoreo, además,
en programas de repoblación y evaluar su efecto.
White spot syndrome virus and Enterocytozoon hepatopenaei in shrimp farms in Costa Rica1
(2020) Nelson Peña-Navarro; Ruth Castro-Vásquez; Gaby Dolz
Introduction. The white spot syndrome virus (WSSV) causes systemic destruction of ectodermal and mesodermal tissues in shrimp and can cause 100 % mortality. Enterocytozoon hepatopenaei (EHP) is an intracellular microsporidian that causes lysis of epithelial cells in hepatopancreatic tubules in shrimp. Objective. Detect the presence of WSSV and EHP in fifteen shrimp farms in the Gulf of Nicoya and the Central Pacific from Costa Rica. Materials and methods. Between January 2017 and July 2018 water during the filling process of the pond, postlarvae, and juvenile shrimp of Penaeus vannamei was collected, during a production cycle in each one of the fifteen farms. Samples were analyzed through polymerase chain reaction (PCR) using primers and protocols to detect the VP41B gene in WSSV, and the small subunit ribosomal RNA gene of EHP. Results. The presence of WSSV was detected in one farm, while EHP was not detected in any of the fifteen farms. The sequencing of the amplified segments of the VP41B gene showed 100 % identity with isolated shrimp sequences in Taiwan and Mexico. Conclusion. WSSV was detected at a very low frequency and EHP was not detected in this study. It is necessary to continue monitoring these agents in the country’s shrimp farms.
In Vitro Evaluation of Postbiotics Produced from Bacterial Isolates Obtained from Rainbow Trout and Nile Tilapia against the Pathogens Yersinia ruckeri and Aeromonas salmonicida subsp. salmonicida
(2023-07-17) Mario Quintanilla-Pineda; Chajira Garrote Achou; Jesús Díaz; Ana Gutiérrez-Falcon; María Bravo; Juan Ignacio Herrera-Muñoz; Nelson Peña-Navarro; Carlos Alvarado; Francisco C. Ibañez; Florencio Marzo
The use of antibiotics in aquaculture leads to the proliferation of multidrug-resistant
bacteria, and an urgent need for developing new alternatives to prevent and control disease has,
thus, arisen. In this scenario, postbiotics represent a promising tool to achieve this purpose; thus,
in this study, isolation and selection of bacteria to further produce and evaluate their postbiotics
antibacterial activity against fish pathogens was executed. In this respect, bacterial isolates from
rainbow trout and Nile tilapia were obtained and tested in vitro against Yersinia ruckeri and Aeromonas
salmonicida subsp. salmonicida. From 369 obtained isolates, 69 were selected after initial evaluation.
Afterwards, additional screening was carried out by spot-on-lawn assay to finally select twelve
isolates; four were identified as Pediococcus acidilactici, seven as Weissella cibaria, and one as Weissella
paramesenteroides by matrix assisted laser desorption/ionization, time-of-flight mass spectrometry
(MALDI-TOF MS). Selected bacteria were used to obtain postbiotic products to test their antagonistic
activity through coculture challenge and broth microdilution assays. The influence of incubation time
prior to postbiotic production on antagonistic behavior was also recorded. Two isolates identified as
W. cibaria were able to significantly reduce (p < 0.05) A. salmonicida subsp. salmonicida’s growth in the
coculture challenge up to 4.49 0.05 Log CFU/mL, and even though the reduction in Y. ruckeri was
not as effective, some inhibition on the pathogen’s growth was reported; at the same time, most of the
postbiotic products obtained showed more antibacterial activity when obtained from broth cultures
incubated for 72 h. Based on the results obtained, the preliminary identification of the isolates that
expressed the highest inhibitory activity was confirmed by partial sequencing as W. cibaria. Through
our study, it can be concluded that postbiotics produced by these strains are useful to inhibit the
growth of the pathogens and could, thereby, be applicable in further research to develop suitable
tools as feed additives for disease control and prevention in aquaculture.