Biology subjects

Soto-Rodriguez, S. A.

Publications and source records attributed to Soto-Rodriguez, S. A..

3 recordsLinked to original sources

bioRxiv2026

Selection of DNA aptamers targeting PirAB toxin for potential biosensing applications in acute hepatopancreatic necrosis disease (AHPND)

The timely detection of AHPND is one of the key factors to avoid the great economic losses that this disease entails for aquaculture. The use of aptamers as detection tools allows us to develop a method focused on the specific needs of the producer, such as simple and easy to use, ability to carry out a safe and rapid response field detection. Vibrio parahaemolyticus is currently known as the main causal agent of AHPND in shrimp cultures, however, it is not limited to this species as a transfer of virulence factors has been observed, including the genes encoding the PirAB binary toxin. The concern that this transfer implies has led us to focus our interest on the PirAB binary toxin as a ligand for the development of aptamers capable of identifying it in the field in early stages and avoiding advanced stages of the disease, giving the producer the ability to take preventive actions and reduce the risk of losses. In the present work we have optimized the SELEX (systematic evolution of ligands by exponential enrichment) aptamer development methodology to rapidly develop candidates capable of detecting both the PirAB complex and its subunits separately, obtaining candidates with a dissociation constant (Kd) of 65 to 700 nM for the PirB subunit and 1 to 3 uM for the PirAB complex. These aptamers provide the first step toward the development of a rapid detection method targeting the causative toxin of AHPND and aid in a new user-friendly approach to early disease detection.

molecular biology↗

bioRxiv2023

Prevalence of pathogenic bacteria detected by qPCR from cultured Nile tilapia (Oreochromis niloticus Linnaeus, 1758) in southwest Mexico

Nile tilapia (Oreochromis niloticus) is one of the most important aquaculture species in the world. When bacteria are present in cultured tilapia but do not cause a declared disease, it makes them asymptomatic carrier organisms. Once environmental or nutritional conditions change, an outbreak may occur. This is why it is so important to detect pathogens before outbreaks occur. This is the first study that use molecular techniques based on PCR to estimate prevalence of fish pathogens in southwest Mexico. During 2018, 2019, 2020 and 2022 samples of internal organs and lesions of Nile tilapia were taken and analyzed for detection of the main bacterial tilapia pathogens using one-step PCR or qPCR. A total of 2396 samples from the internal organs of Nile tilapia pond and cage cultured come from the Mexican Pacific southwest states of Guerrero, Oaxaca and Chiapas were analyzed. Most of the sampled tilapias were apparently healthy and had no relation between the clinical signs and the pathogens detection was found. No Francisella sp. was detected in any sample, Staphylococcus sp. was the most prevalent bacterial genus from the three states over time (from 0 to 64 %). Prevalence of Aeromonas sp. was from 0 to 4.3 %, although the fish pathogen A. dhakensis was not detected. Meanwhile, S. iniae was only detected in Chiapas in 2019 at low prevalence (1.4 %) and S. agalactiae was detected in the three sites at high prevalence (from 0 to 59 %). Both Streptococcus can cause streptococcosis, the most dangerous re-emergent disease to cultured tilapia, which means a great risk for tilapia farming in Mexico.

microbiology↗

bioRxiv2021

First evidence of nocardiosis in farmed red drum (Sciaenops ocellatus, Linnaeus) caused by Nocardia seriolae in the Gulf of Mexico

Between August and December 2013, the offshore cages of a commercial marine farm culturing red drum Sciaenops ocellatus in Campeche Bay were affected by an outbreak of an ulcerative granulomatous disease, reaching 70% cumulative mortality. Thirty-one adults displaying open ulcers on the skin were submitted to our laboratory for diagnosis. Multiple white-yellowish nodules (0.1-0.5 cm in diameter) were present in all internal organs, where the kidney and the spleen were the most severely affected. Histopathological observations of these organs evinced typical granulomatous formations. Gram and Ziehl-Neelsen stains on tissue imprints, bacterial swabs and tissue sections revealed Gram-positive, acid-fast, branching beaded long rod filamentous bacteria. Tissue samples resulted positive for nocardiosis when a Nocardia genus specific nested PCR was used. Definite identification at the species level and taxonomic positioning of the fastidious pathogen was achieved through a specific Nocardia seriolae PCR and by sequencing the gyrB gene of pure isolates. After application of antibiotics during fry production, a posterior follow-up monitoring (from 2014 to 2017) detected mild but recurrent outbreaks of the bacteria with no seasonality pattern. To the extent of our current knowledge, this is the first report of piscine nocardiosis (in a new host -red drum) in Mexico.

microbiology↗