ABSTRACT. The aim of the present work was to perform a genetic verification of Herichthys species and assess their phylogenetic relationship by Cytochrome B gene resequencing in two sampling sites from Tamaulipas. Samples from Panal river in Playa Tepehuajes, Soto la Marina and samples from Carrizal river in Aldama were included. The complete sequences were analyzed with bioinformatics tools and the genetic similarity showed that Aldama samples resembled Herichthys carpintis species (> 99%) and Tepehuajes samples were confirmed as Herichthys cyanoguttatus. The assessed phylogenetic trees for genetic distance comparison among current samples and other cichlids species support the previously found results. This study suggest that cytochrome B gene is useful for genetic identification of cichlid species, such as from Tamaulipas.

RESUMEN. El objetivo del presente estudio fue verificar genéticamente la identidad de especies del genero Herichthys y estudiar su relación fiolgenética utilizando secuencias de citocromo B mitocondrial. Se incluyeron muestras de dos sitios de Tamaulipas de dicha especie: en el río Panal ubicado en Playa Tepehuajes, Soto la Marina y en el río Carrizal ubicado en Aldama. Se analizaron las secuencias completas del gen mitocondrial citocromo B con herramientas bioinformáticas, los resultados de similitud genética indican que las muestras de Aldama tienen mayor similitud (> 99%) con la especie Herichthys carpintis. Mientras que las muestras de Tepehuajes, confirmaron la identidad supuesta con Herichthys cyanoguttatus. Los árboles filogenéticos analizados con la finalidad de comparar la distancia genética de las muestras con diferentes especies de cíclidos, confirmaron la similitud encontrada previamente. Los resultados sugieren que el citocromo B es un marcador útil en la identificación de especies de cíclidos de Tamaulipas.

DNA from four cattle breeds was used to re-sequence all of the exons and 56% of the introns of the bovine tyrosine hydroxylase (TH) gene and 97% and 13% of the bovine dopamine b-hydroxylase (DBH) coding and non-coding sequences, respectively. Two novel single nucleotide polymorphisms (SNPs) and a microsatellite motif were found in the TH sequences. The DBH sequences contained 62 nucleotide changes, including eight non-synonymous SNPs (nsSNPs) that are of particular interest because they may alter protein function and therefore affect the phenotype. These DBH nsSNPs resulted in amino acid substitutions that were predicted to destabilize the protein structure. Six SNPs (one from TH and five from DBH non-synonymous SNPs) were genotyped in 140 animals; all of them were polymorphic and had a minor allele frequency of > 9%. There were significant differences in the intra- and inter-population haplotype distributions. The haplotype differences between Brahman cattle and the three B. t. taurus breeds (Charolais, Holstein and Lidia) were interesting from a behavioural point of view because of the differences in temperament between these breeds.

Background: Channel catfish are one of the most important aquaculture species raised for food purposes in Mexico. Two temporal samples were obtained from the largest channel catfish breeding hatchery in Mexico to identify changes in genetic diversity and inbreeding that are promoted by traditional hatchery management. Results: The genetic parameter analysis of 11 microsatellite loci showed no significant change in genetic diversity (p > 0.05). However, a significant heterozygosis deficiency was detected (p < 0.001), and genetic structure analysis indicated moderate differentiation between the temporally divided populations (F ST = 0.08). A moderate level of inbreeding and a slight increase of the inbreeding coefficient from 0.23 to 0.27 were the result of traditional hatchery practices. To achieve an effective population size, the temporal approach resulted in a limited number of breeders to maintain genetic variability. Conclusions: Although no significant change in genetic diversity parameters was found, the heterozygote deficiency and low effective number of breeders suggest that there is a risk for increased inbreeding. Thus, we propose the need for controlled reproductive management and the establishment of genetic programs in hatcheries. Molecular tools can provide valuable information to facilitate the achievement of these goals.