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In this study, four experimental assays were conducted to evaluate the use of a new silver nanoparticle formulation named Argovit-4, which was prepared with slight modifications to enhance its biological activity against white spot syndrome virus (WSSV) in shrimp culture. The goals of these assays were to (1) determine the protective effect of Argovit-4 against WSSV, (2) determine whether Argovit-4 supplemented in feed exhibits toxicity towards shrimp, (3) determine whether Argovit-4 as antiviral additive in feed can prevent or delay/reduce WSSV-induced shrimp mortality, and (4) determine whether Argovit-4 supplemented in feed alters the early stages of the shrimp immune response. In bioassay 1, several viral inocula calibrated at 7 SID50(shrimp infectious doses 50% endpoint) were exposed to 40, 100, 200 and 1,000 ng/SID50 of Ag+ and then intramuscularly injected into shrimp for 96 h. In bioassay 2, shrimp were fed Argovit-4 supplemented in feed at different concentrations (10, 100 and 1,000 µg per gram of feed) for 192 h. In bioassay 3, shrimp were treated with Argovit-4 supplemented in feed at different concentrations and then challenged against WSSV for 192 h. In bioassay 4, quantitative real-time RT-qPCR was performed to measure the transcriptional responses of five immune-relevant genes in haemocytes of experimental shrimp treated with Argovit-4 supplemented in feed at 0, 6, 12, 24 and 48 h. The intramuscularly injected Argovit-4 showed a dose-dependent effect (p < 0.05) on the cumulative shrimp mortality from 0–96 h post-infection. In the second bioassay, shrimp fed Argovit-4 supplemented in feed did not show signs of toxicity for the assayed doses over the 192-h experiment. The third and fourth bioassays showed that shrimp challenged with WSSV at 1,000 µg/g feed exhibited reduced mortality without altering the expression of some immune system-related genes according to the observed level of transcriptional. This study is the first show that the new Argovit-4 formulation has potential as an antiviral additive in feed against WSSV and demonstrates a practical therapeutic strategy to control WSSV and possibly other invertebrate pathogens in shrimp aquaculture.

White spot syndrome virus (WSSV) is the most aggressive disease affecting cultured shrimp. One possibility to tackle it is by means of RNA interference (RNAi) induced by the presence of double-stranded RNA (dsRNA). Normally, dsRNA is a product of the cellular machinery to gene regulation, but it can be produced synthetically and introduced into specific tissues or cells and thereby induce RNAi. Although in vitro production of dsRNA is possible, this is high cost. An alternative is to produce dsRNA in vivo using biological systems such as bacteria or yeasts. In this regard, Yarrowia lipolytica offers distinctive advantages for dsRNA production. The objective was to develop a Y. lipolytica strain able to produce dsRNA-specific against WSSV and to evaluate its antiviral activity in the white leg shrimp Litopenaeus vannamei.From the 0.4 and 0.6 Kb fragments of the ORF89 gene, a dsRNA-ORF89-producing construct was built in the plasmid pJC410; the resulting construct (pARY410) was used to transform Y. lipolytica to drive the specific expression of dsRNA-ORF89.Yeast colonies positive to the WSSV-ORF89 gene were selected. The expression of dsRNA-ORF89 and RNAse III was measured being detected at 32 and 48 hr. Subsequently, the antiviral activity of dsRNA-ORF89 was tested in a WSSV challenge bioassay. The results showed survival in dsRNA-ORF89 shrimp (25%) compared to control organisms treated with total RNA from the yeast P01-AS harvested at 32 hr. In conclusion, Y. lipolytica is a convenient host to produce and deliver dsRNA-ORF89 able to protect WSSV-challenged shrimp. K E Y W O R D Santiviral, Litopenaeus vannamei, ORF89, RNAi, RNAse III

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University teachers have adapted to different situations during the development of distance learning due to the pandemic caused by the COVID-19 virus. This study was conducted by assigning a data collection instrument to 993 teachers who are part of 15 technological universities (TUs) and 7 polytechnic universities (PUs) to determine how they were affected by COVID-19. The questions asked were related to the social, economic, academic, emotional, and health effects experienced. The results show that 63% of the teachers working online complained that online teaching invaded their family privacy; 56% pointed out that working from home and the virtual classes affected their performance as teachers; 90% of the teachers thought that they dedicated too much extra to preparing for their classes; 15% were stressed; 4% felt negative under the new teaching scheme of virtual classes; finally, 38% of the teachers stated that repeated interaction with electronic devices had a lot of negative impacts on their emotional wellbeing. By means of a G-test, it was determined that gender was independent from the studied effects. Through a multiple correspondence analysis (MCA), it was determined that, of the total number of teachers who responded to the questionnaire, half were comfortable with the online teaching model and the other half were not. The most impacted effects were the economic, training and connectivity independently from the gender.

Objetivo. Evaluar los efectos de la zona de habitad y sexo en la respuesta bioquímica sérica y morfométrica de Ichthyoelephas humeralis en ecosistemas loticos de la provincia Los Ríos, Ecuador. Materiales y métodos. Se identificó una de las especies nativas (I. humeralis) que más se comercializan en los cantones de Quevedo, Mocache y Fumisa de la provincia Los Ríos. Se capturaron 60 ejemplares por cada zona (180 total). Se realizó el sexado y se determinó el peso vivo, la longitud, el grosor de la cabeza, cuerpo y cola; factor de condición y bioquímica sanguínea (glucosa, colesterol y triglicéridos). Resultados. Para los indicadores morfométricos no hubo interacción zona-sexo. Solo existieron diferencias significativas (p<0.05) para el efecto del sexo sobre el peso vivo, longitud, grosor de la cabeza, cuerpo y cola, con los mayores valores para los machos (284.98 g; 29.32 cm; 6.77 cm; 14.81 cm y 7.80 cm, respectivamente) excepto para el Factor de condición el cual no mostró diferencias estadísticas. Para la bioquímica sanguínea los resultados más elevados para glucosa y triglicéridos en Quevedo con 162 mg/dL y 320.67 mg/dL, respectivamente mientras que para el colesterol fue de 130 mg/dL para Fumisa. Conclusiones. Se evidenció el efecto del sexo sobre los indicadores morfométricos, con los mejores resultados para los machos. Mientras que la bioquímica sanguínea mostró variabilidad con respecto a las zonas con los mayores resultados para Quevedo, producto a las fluctuaciones en condiciones naturales del ambiente y la alimentación.

El compost es una forma principal para degradar desechos de origen orgánicos; no obstante, todo el procedimiento requiere de largos tiempo de maduración por lo cual, es indispensable la búsqueda de formas rápidas para descomponer y transformar estos desechos en subproductos con alto valor agronómico. El objetivo de este estudio fue determinar el efecto de sustancias azucaradas en la descomposición de sustratos orgánicos para elaborar compost. Las sustancias investigadas fueron azúcar, melaza y jugo de caña (Saccharum officinarum), mezclados con un sustrato orgánico compuesto por 30% estiércol, 50% panca de maíz, 10% de restos de leguminosa, 9% de tierra y 1% de ceniza. El diseño experimental fue completamente al azar, con 16 unidades experimentales, un testigo absoluto y cuatro repeticiones. Las variables evaluadas fueron días para la descomposición, temperatura, humedad, peso del sustrato y contenido de nutrimentos. La melaza mezclada con residuos orgánicos disminuyó 6 días (9.68%) el período de descomposición, con relación al testigo (62 días). El tratamiento con melaza añadida presentó el mayor descenso de temperatura (8.7 ºC), aunque no se encontraron diferencias significativas entre tratamientos, al inicio y al final del ensayo. El contenido de humedad entre los tratamientos osciló entre 56.5 y 59.0%, sin embargo, las diferencias no fueron significativas. El tratamiento con melaza fue el que presentó la mayor pérdida de peso (10.8 kg) durante la descomposición del sustrato orgánico; no obstante, no hubo diferencias en el pH y contenido de nutrimentos (B, Ca, Cu, K, Mg, N, P, S, Zn, M.O.). El tratamiento con mayor concentración de nutrimientos fue el conformado por sustancias orgánicas y melaza, por lo cual, se recomienda su uso o integración para acelerar el proceso de descomposición en el compost.