Browsing by Author "Nelson Peña-Navarro"
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Item Análisis físico-químico de filetes de la especie exótica Hemiancistrus aspidolepis en Costa Rica(2021) Nelson Peña-Navarro; Paulina Vargas-AlpízarIntroducción. Cuando especies de animales invasoras se introducen en un ecosistema que no es su área de distribución natural, su control podría estar determinado por la posibilidad de utilizar estos organismos para el consumo humano u otra alternativa de manejo. Objetivo. Determinar las características físico-químicas del filete de H. aspidolepis, y comparar su calidad nutricional con especies de peces de consumo humano de origen marino y de aguas continentales. Materiales y métodos. Se recolectaron 109 peces en tres Refugios de Vida Silvestre en Costa Rica, durante el 2017, se pesaron en fresco y sin vísceras, además se pesó cada filete, las vísceras y la carcasa. Se les realizó un análisis proximal, para determinar el contenido de ácidos grasos, minerales y mercurio. Resultados. La longitud promedio de los individuos recolectados fue de 25,35 cm y el peso promedio fue de 162,55 g, de los cuales el 8,2 % fueron vísceras, y 19,02 % fue músculo. Para cada muestra se obtuvieron promedios por cada 100 g de: 80,69 g de agua, 17,64 g de proteína y 73,40 kcal de energía. Los niveles de grasa trans y carbohidratos totales fueron de 0,01 y 0,55 g 100 g-1, respectivamente. Los minerales por cada 100 g fueron 281,81 mg de potasio, 28,87 mg de sodio y 1,23 mg de hierro. Los ácidos grasos en mayor cantidad fueron: palmítico (23,64 %), esteárico (9,43 %) y tricosanoico (7,26 %). El nivel de mercurio total fue inferior a 0,15 ppm. Conclusiones. Los individuos colectados no poseían tallas ni porcentajes de peso de filetes similares a los utilizados para mercado y consumo humano. H. aspidolepis posee semejanzas en contenido proximal, ácidos grasos y minerales con respecto a algunos peces de consumo humano; los contenidos de proteínas y lípidos la hacen apta para su consumo y comercialización.Item Detección de IHHNV en el cultivo de Litopenaeus vannamei en Costa Rica(2021) Jose Francisco Parajeles-Mora; Nelson Peña-Navarro; Antony Solorzano-Morales; Gaby DolzEl virus de la necrosis hipodérmica y hematopoyética infecciosa (IHHNV) produce deformidades cuticulares y reducción del crecimiento del camarón blanco (Litopenaeus vannamei), lo que genera pérdidas productivas por un menor peso de cosecha y menores precios de mercado. Aunque se han descrito linajes patógenos y no patógenos del agente, se desconoce si estos están presentes en el país. Objetivo. Caracterizar los linajes de IHHNV presentes en fincas de camarón blanco en Costa Rica. Materiales y métodos. Entre 2017 y 2018 se investigaron quince granjas camaroneras distribuidas en el Golfo de Nicoya, Guanacaste, Costa Rica. En estas fincas se recolectaron muestras de agua, postlarvas y camarones juveniles, durante un ciclo de producción de tres meses, se tomaron los parámetros fisicoquímicos del agua de los estanques y se aplicó una encuesta a los productores para conocer si tenían conocimiento sobre la enfermedad y si sospechaban de la presencia del agente en sus establecimientos. Las muestras recolectadas se analizaron mediante Reacción en Cadena de Polimerasa (PCR) y secuenciación. Resultados. La presencia de IHHNV se determinó en el 86,6 % (13/15) de las fincas analizadas, la secuenciación de los productos amplificados estableció la presencia del linaje III de IHHNV, con un 99,2 %-100,0 % (386-389/389 pb) de similitud con la secuencia aislada en L. vannamei de Venezuela (KM485615.1). Los parámetros fisicoquímicos del agua se determinaron como deficientes. Un 53,3 % de productores no tenían conocimiento de IHHNV, mientras que los restantes sospechaban tener el agente en su finca. Conclusión. El linaje patógeno III de IHHNV estuvo presente en la mayoría de las fincas. Se recomienda capacitar a los productores y establecer protocolos de bienestar, manejo y bioseguridad para así mejorar los parámetros productivos de sus fincas.Item 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 MarzoThe 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.Item Molecular detection of acute hepatopancreatic necrosis disease (AHPND) in Penaeus vannamei shrimps in Costa Rica(2020) Nelson Peña-Navarro; Ruth Castro-Vásquez; Bernardo Vargas-Leitón; Gaby DolzAcute hepatopancreatic necrosis disease (AHPND) is a bacterial disease associated to severe mortality in farmed shrimps, and caused by Vibrio parahaemolyticus containing plasmid pVA-1 encoding pirA and pirB toxins. This study investigates the presence of Vibrio spp. carrying plasmid pVA-1 in post larvae and juveniles Penaeus vannamei from farms located in Costa Rica. Moreover, a possible corelation between Vibrio spp. presence, management parameters, and water quality was also investigated. Between 2017 and 2018, post larvae, the first water pumped into ponds, and juvenile shrimp (6 to 7 weeks after stocking) were collected from 15 farms located in the Gulf of Nicoya and the country's Central Pacific region. On the day when the juvenile shrimp were collected, a survey was applied to farmers to obtain information about management conditions, finally physicalchemical parameters of pond water were measured. Plasmidic pVA-1 pirA and pirB genes were detected in hepatopancreas of juvenile shrimp in 5 (33.3%) farms, while Vibrio spp. were found in 6 (40.0%) farms. Sequencing of pVA-1, pirA and pirB genes showed 99–100% similarity to pathogenic Vibrio parahemolyticus XN89 homologous genes identified in Vietnamese shrimps. Statistically significant differences were found in the water volume (p < .03), rate of water replacement (p < .04), and farms disease history (p < .05). A correlation between presence of Vibrio spp. and water quality was not established. The molecular diagnosis of Vibrio spp., the plasmid and the genes encoding toxins that are associated with AHPND are reported for the first time in Costa Rica. Further studies aimed to isolate AHPND-causing Vibrio spp. from ponds, to generate histopathological data, and to establish economic losses due to AHPND mortalities in Penaeus vannamei farms, are needed to clarify the role and pathogenic features of Vibrio spp. in AHPND.Item Molecular identification of Streptococcus sp. and antibiotic resistance genes present in Tilapia farms (Oreochromis niloticus) from the Northern Pacific region, Costa Rica(2021) Karen Oviedo-Bolaños; Jorengeth Abad Rodríguez-Rodríguez; Carolina Sancho-Blanco; Juan Esteban Barquero-Chanto; Nelson Peña-Navarro; Cesar Marcial Escobedo-Bonilla; Rodolfo Umaña-CastroStreptococcosis is a bacterial disease in tilapia that produces economic losses, caused mainly by Streptococcus agalactiae and S. iniae. It is treated using oxytetracycline and florfenicol, which when inappropriately used promotes the selection of antibiotic resistance genes (ARGs). The disease has been mainly associated with stress events such as variations in temperature. The aims of the present study were (1) to detect by molecular methods two species of Streptococcus sp. in a tilapia farm, (2) to relate their presence to physicochemical parameters in the culture system, and (3) to detect the presence of ARGs in tilapia tissues and/or ponds. Tilapia grow-out ponds (n = 30) were sampled, collecting 15 individuals per pond. The physicochemical parameters of water were measured in each pond. Per pond, organs such as the liver, spleen, brain, and eyes were collected from each individual. Then, each organ type was pooled with the respective organ of the other individuals, processed for DNA extraction, and used for PCR analyses to determine the presence of S. agalactiae and S. iniae and for the detection of ARGs (tetM, tetO, fexA, and ermB). The correlations between the presence of S. agalactiae and water physicochemical parameters were determined. Sixty percent of the ponds and 46% of the organ pools were positive for S. agalactiae, whereas S. iniae was not detected. The positive samples showed the following resistance genes: tet(O) (29.1%), tet(M) (12.7%), and erm(B) (1.8%). A moderate but significant positive correlation was found between temperature and the presence of S. agalactiae. This work reported the molecular detection of two species of Streptococcus and ARGs, providing information that allows fast and effective control of these pathogens in tilapia farming. In addition, a future complementary study on Streptococcus sp. serotype distribution and antibiotic resistance genes from tilapia cultured in Costa Rica could also contribute to increase the knowledge of S. agalactiae infections in tilapia farming worldwide.Item 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-EnríquezIntroducción: 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.Item White spot syndrome virus and Enterocytozoon hepatopenaei in shrimp farms in Costa Rica1(2020) Nelson Peña-Navarro; Ruth Castro-Vásquez; Gaby DolzIntroduction. 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.