Resumen La transferencia de embriones (TE) es considerada actualmente como una herramienta biotecnológica con gran importancia para multiplicar y obtener individuos con potencialidades productivas y alto mérito genético. El objetivo de este estudio fue determinar la influencia de factores como ITH, tamaño del CL, estado de desarrollo del embrión y peso sobre la tasa de preñez mediante transferencia de embriones por fertilización in vitro en novillas multirraciales. Se seleccionaron 840 novillas como receptoras, con edades promedio de 3 años, un peso de 346.5 ± 33.4 kg de peso vivo, a las cuales se les aplicó un protocolo de sincronización para TE, previo registro del estadio del embrión, seguimiento ecográfico y se realizó el monitoreo de variables medioambientales. La información se analizó mediante un modelo de regresión logística para determinar la correlación entre las variables independientes sobre la variable dicotómica de respuesta tasa de preñez. Se determinó la influencia del tamaño del cuerpo lúteo (CL) dado las diferencias significativas (P<0.05) en los tamaños de CL1 y CL2. También, se encontró diferencias (P<0.05) con los estadios de BL y BX. En contraste, no se encontró diferencias estadísticas (P>0.05) en las demás variables. El presente estudio evidenció el impacto del tamaño del CL y el desarrollo del embrión en el éxito de la técnica de TE.

Abstract Embryo transfer (ET) is currently considered a biotechnological tool with great importance to multiply and obtain individuals with productive potential and high genetic merit. The objective of this study was to determine the influence of factors such as THI, CL size, embryo development status and weight on the rate of pregnancy by embryo transfer by in vitro fertilization in multibreed heifers. Eight hundred forty heifers were selected as recipients, with an average age of 3 years, a weight of 346.5 ± 33.4 kg of live weight, to which a synchronization protocol for ET was applied, after recording the stage of the embryo, ultrasound monitoring and the environmental variables were monitored. The information was analyzed using a logistic regression model to determine the correlation between the independent variables and the dichotomous response variable pregnancy rate. The influence of corpus luteum (CL) size was determined given the significant differences (P<0.05) in the sizes of CL1 and CL2. Differences (P<0.05) were also found with the stages of BL and BX. In contrast, no statistical differences (P>0.05) were found in the other variables. The present study showed the impact of CL size and embryo development on the success of the ET technique.

BACKGROUND Forty percent of the world’s population live in areas where they are at risk from dengue fever, dengue hemorrhagic fever, and dengue shock syndrome. Dengue viruses are transmitted primarily by the mosquito Aedes aegypti. In Cali, Colombia, approximately 30% of field collected Ae. aegypti are naturally refractory to all four dengue serotypes. OBJECTIVES Use RNA-sequencing to identify those genes that determine refractoriness in feral mosquitoes to dengue. This information can be used in gene editing strategies to reduce dengue transmission. METHODS We employed a full factorial design, analyzing differential gene expression across time (24, 36 and 48 h post bloodmeal), feeding treatment (blood or blood + dengue-2) and strain (susceptible or refractory). Sequences were aligned to the reference Ae. aegypti genome for identification, assembled to visualize transcript structure, and analyzed for dynamic gene expression changes. A variety of clustering techniques was used to identify the differentially expressed genes. FINDINGS We identified a subset of genes that likely assist dengue entry and replication in susceptible mosquitoes and contribute to vector competence. MAIN CONCLUSIONS The differential expression of specific genes by refractory and susceptible mosquitoes could determine the phenotype, and may be used to in gene editing strategies to reduce dengue transmission.

ABSTRACT Considering that glycyrrhizic acid (GRA) has been shown to have in-vitro and in-vivo antiviral activity against a wide range of viruses as well as immunostimulating activity, a trial to evaluate its effects on the performance and the immune response against Newcastle disease of broiler chickens was carried out. The study was performed with one-day-old Ross x Ross broiler chickens. GRA was added to the drinking water throughout the 49-d production cycle at a dose of 0.03%. Sample size of the trial was established in a pilot assay. Results showed that broiler chickens treated with GRA presented better weight gain, final body weight, feed conversion ratio, and lower mortality rate than the non-treated controls. In addition, GRA-treated birds presented higher antibody titers against Newcastle disease virus and more efficient cellular immune response, as demonstrated by the late-hypersensitivity response test. Blood lymphocyte and thrombocyte counts also increased in this group. The histopathological examination of the bursa, spleen, and thymus revealed that only the thymus of the GRA-treated group had a clearly defined increase in cortex thickness on day 49. The bursa showed a higher number of lymphoid lesions in CG on days 21 and 49 compared with the GRA group. These results suggest that GRA has growth promotion properties, which are possibly linked to immune-based effects.

The objective of this research was to identify environmental risk factors for cutaneous leishmaniasis (CL) in Colombia and map high-risk municipalities. The study area was the Colombian Andean region, comprising 715 rural and urban municipalities. We used 10 years of CL surveillance: 2000-2009. We used spatial-temporal analysis - conditional autoregressive Poisson random effects modelling - in a Bayesian framework to model the dependence of municipality-level incidence on land use, climate, elevation and population density. Bivariable spatial analysis identified rainforests, forests and secondary vegetation, temperature, and annual precipitation as positively associated with CL incidence. By contrast, livestock agroecosystems and temperature seasonality were negatively associated. Multivariable analysis identified land use - rainforests and agro-livestock - and climate - temperature, rainfall and temperature seasonality - as best predictors of CL. We conclude that climate and land use can be used to identify areas at high risk of CL and that this approach is potentially applicable elsewhere in Latin America.