Use of probiotics in the catfish Sorubim cuspicaudus larviculture

Sorubim cuspicaudus, a migratory catfish distributed in the Magdalena, Sinú, and Catatumbo river basins, is categorized as vulnerable to extinction. Production of fingerlings in controlled environments stands as a strategic conservation approach, and larviculture is a critical phase in rearing this species. Probiotics are used for improvement in the critical stages of fingerling production. The study aimed to evaluate the use of probiotics (Bacillus subtilis and Bacillus licheniformis) during the larviculture phase of S. cuspicaudus. Larvae at 42 hours post-hatching (1.5±0.1mg, total length 5.7±0.4mm) were treated with four levels of probiotic inclusion in the water: 0, 5, 10, and 20ppm for 22 days. Water quality remained within suitable ranges for neotropical catfish species larviculture and the parameters assessed were weight gain (Gw), length gain (Gl), specific growth rate (G), survival rate (S), stress resistance (Sr), intestinal fold length (LF), and colony-forming units (CFU) count. Results showed higher Gl (22.23±3.5mm), Gw (40.0±12.6mg), G (14.9±1.5%/day), LP (205±72.7µm), and CFU (118.7±80.9) were found at 20 ppm (p0.05). The findings of this study suggest that probiotics (Bacillus subtilis and Bacillus licheniformis) could be used as an alternative to advance in the S. cuspicaudus larviculture.

Sorubim cuspicaudus, un bagre migratorio distribuido en las cuencas de los ríos Magdalena, Sinú y Catatumbo, se encuentra catalogado como una especie vulnerable a la extinción. La producción de alevinos en ambientes controlados es considerada como una estrategia crucial para su conservación, y la larvicultura es una fase crítica en la cría de esta especie. Para mejorar esta fase crítica de producción de alevinos se utilizan probióticos. El estudio tenía como objetivo evaluar el uso de probióticos (Bacillus subtilis y Bacillus licheniformis) durante la fase de larvicultura de S. cuspicaudus. Las larvas, a las 42 horas post eclosión (1,5±0,1mg, longitud total 5,7±0,4mm) fueron tratadas con cuatro niveles de inclusión de probióticos en el agua: 0, 5, 10 y 20ppm durante 22 días. La calidad del agua se mantuvo dentro de los rangos adecuados para la larvicultura de especies neotropicales de bagre y los parámetros evaluados fueron el aumento de peso (Gw), el aumento de longitud (GL), la tasa específica de crecimiento (G), la tasa de supervivencia (S), la resistencia al estrés (Sr), la longitud del pliegue intestinal (LF) y el recuento de unidades formadoras de colonias (UFC). Los resultados mostraron mayores GL (22,23±3,5 mm), Gw (40,0±12,6 mg), G (14,9±1,5%/día), LP (205±72,7 µm) y UFC (118,7±80,9) a 20 ppm (p0,05). Los resultados de este estudio sugieren que los probióticos (Bacillus subtilis y Bacillus licheniformis) podrían utilizarse como alternativa para avanzar en la larvicultura de S. cuspicaudus.

Draft genome assembly for the colombian freshwater bocachico fish, Prochilodus magdalenae.

We report the first draft genome assembly for Prochilodus magdalenae, the leading representative species of the Prochilodontidae family in Colombia. This 1.2-Gb assembly, with a GC content of 42.0% and a repetitive content of around 31.0%, is in the range of previously reported characid species genomes. Annotation identified 34,725 nuclear genes, and BUSCO completeness value was 94.9%. Gene ontology and primary metabolic pathway annotations indicate similar gene profiles for P. magdalenae and the closest species with annotated genomes: blind cave fish (Astyanax mexicanus) and red piranha (Pygocentrus nattereri). A comparative analysis showed similar genome traits to other characid species. The fully sequenced and annotated mitochondrial genome reproduces the taxonomic classification of P. magdalenae and confirms the low mitochondrial genetic divergence inside the Prochilodus genus. Phylogenomic analysis, using nuclear single-copy orthologous genes, also confirmed the evolutionary position of the species. This genome assembly provides a high-resolution genetic resource for sustainable P. magdalenae management in Colombia and, as the first genome assembly for the Prochilodontidae family, will contribute to fish genomics throughout South America.

Morphological characterization of the adherence and invasion of Streptococcus agalactiae to the intestinal mucosa of tilapia Oreochromis sp.: An in vitro model.

Streptococcosis in tilapia Oreochromis sp. is possibly the most important bacterial disease for fish production worldwide. In Colombia, streptococcosis is caused by Streptococcus agalactiae (GBS), but in other countries, Streptococcus iniae is also involved. Prevention of streptococcosis is required and must be addressed for economic, social, international trade and public health reasons. This research used an in vitro culture of tilapia intestine to detail the intestinal mucosal response once the pathogen contacts the epithelium. We show that S. agalactiae sheds off its capsule to adhere to the epithelium. The bacterium adheres as a single individuum, in groups or in chains and is able to divide on the apical border of enterocytes. GBS adheres at and invades exclusively through the apical portion of the intestinal folds, using the transepithelial route. Once within the cytoplasm of enterocytes, the bacteria continue to divide. On the basolateral side of the epithelium, the microorganisms leave the cells to reach the propria and travel through the microcirculation. No evidence of an immuno-inflammatory reaction or goblet cell response in the epithelium or the lamina propria was seen during the process of adherence and invasion of the pathogen.

Single Cell Real-Time miRNAs Sensing Based on Nanomotors.

A nanomotor-based strategy for rapid single-step intracellular biosensing of a target miRNA, expressed in intact cancer cells, at the single cell level is described. The new concept relies on the use of ultrasound (US) propelled dye-labeled single-stranded DNA (ssDNA)/graphene-oxide (GO) coated gold nanowires (AuNWs) capable of penetrating intact cancer cells. Once the nanomotor is internalized into the cell, the quenched fluorescence signal (produced by the π-π interaction between GO and a dye-labeled ssDNA) is recovered due to the displacement of the dye-ssDNA probe from the motor GO-quenching surface upon binding with the target miRNA-21, leading to an attractive intracellular "OFF-ON" fluorescence switching. The faster internalization process of the US-powered nanomotors and their rapid movement into the cells increase the likelihood of probe-target contacts, leading to a highly efficient and rapid hybridization. The ability of the nanomotor-based method to screen cancer cells based on the endogenous content of the target miRNA has been demonstrated by measuring the fluorescence signal in two types of cancer cells (MCF-7 and HeLa) with significantly different miRNA-21 expression levels. This single-step, motor-based miRNAs sensing approach enables rapid "on the move" specific detection of the target miRNA-21, even in single cells with an extremely low endogenous miRNA-21 content, allowing precise and real-time monitoring of intracellular miRNA expression.