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 (FST = 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.

The channel catfish farming in Mexico began in the 1970s. One of the most important areas of production is its northeastern region. Traditionally, the channel catfish farmers have attempted to preserve their original genetic stock. After more than 30 yr of production, the genetic relationship between stocks has not been assessed. The goal of this study was to evaluate the genetic differentiation between five channel catfish farm populations, using 13 microsatellite markers. A total of 154 fin clip samples were collected from five channel catfish farms in Tamaulipas. We also included 31 individuals of the commercial strain NWAC103. In each population, we calculated parameter of genetic variability: inbreeding coefficient (FIS), pairwise differentiation (FST), and genetic distance (DC). For the inference of populations and individual assignment two Bayesian methods were used. Genetic variability parameters were NA = 9.54–11.08 and AE = 5.40–6.67. Hardy–Weinberg equilibrium deviations were observed for all farm populations examined, and a deficit of heterozygotes was found. Signals of inbreeding were observed, particularly for the ACU (Acuamex) hatchery. Populations EKA (Empresas Karol) and ACU showed higher genetic differentiation values with respect to the commercial strain (FST = 0.107; FST = 0.082, respectively). Moderated genetic differences (FST = 0.067; DC = 0.080) were observed between the EKA and ACU. Clustering analysis revealed a well‐defined group between EKA and TPA (El Tiron Parejo). In the Bayesian analysis three groups were defined. The first group was formed by EKA and TPA, the second group included ACU, LAJ (La Lajilla), and PRO (Prodatec). In the third group was the commercial strain. In the assignment of individuals, EKA and ACU were represented by exclusive genotypes. Identification of two genetic stocks, one located in the EKA and the other in the ACU population, will be relevant for future management of these hatcheries. Additionally, the information from microsatellites and the statistical procedures presented will be important tools for genetic monitoring of these farm populations.

No abstract

The white-tailed deer (Odocoileus virginianus) is one of the most important species related to sport hunting in northern Mexico. During the last decade, this species has been subjected to intensive breeding to achieve improvements in certain desired traits (i.e., antlers). This alleged intensive management of bringing originally wild populations into captivity might have harmful consequences on genetic diversity. In this short research paper we estimate and discuss the consequences of that transition, as assessed by a microsatellite genetic marker analysis. The results show that no short-term changes in genetic diversity parameters were promoted by captivity; however, a genetic diversity condition maintained by artificial genetic flow was identified, perhaps allowing for the required introgression of gene diversity into this closed population. A wider analysis is recommended and the implications are discussed. Within a realistic forecast of expanding sport hunting, the achievement of useful, pragmatic, and strict conservancy programs of this species, considering approaches such as those used here, will be necessary.

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 β-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.

Mexico is the native site of 10 species of the genus Ictalurus, among which the Channel Catfish I. punctatus has great presence in worldwide aquaculture. Wild populations of catfish not only constitute a biological resource but have a great potential for aquaculture. Recently, this species was classified as an invasive organism by the Mexican government. The aim of this study was to determine the structure and genetic diversity of Channel Catfish belonging to native and introduced freshwater populations within Mexico. Using 11 DNA microsatellite loci, we analyzed 292 fish sampled from four rivers and five reservoirs. Observed heterozygosity values ranged between 0.66 and 0.80. The genetic distance analysis showed low to high differentiation among populations (overall genetic differentiation index FST = 0.14). Bayesian coancestry analysis identified two ancestral groups. A single management population on central Tamaulipas can be suggested. The findings of the present study provide the basis for future characterization of productive traits of Mexican Channel Catfish populations in order to use the species as a breeding source for aquaculture. The lower Rio Grande population is one of the most ancient and ecologically relevant Channel Catfish populations in Mexico, and this study identifies it as the most vulnerable. Free‐living populations of Channel Catfish, although they have been heedlessly spread, constitute a valuable natural resource that deserves our best effort to preserve.

No abstract

The scrotal circumference is one of the main characteristics related to fertility of the bovine male and female. Its study through genetic and genomic tools would help to the discovery of favorable variation and genetic architecture to promote its selection. The aim of this work was to carry out a genome- wide association study using a large microarray of SNPs, to identify variations and candidate genes associated with the studied trait, for which information from 141 Charolais bulls was used. Four markers found, rs110416965, rs110130953, rs43423602 and rs29003417, showed significant association at the genome level. Three of them are found within candidate genes (RBFOX2, TTF2 and CXCL2). This information contributes to the understanding of the genetic architecture of this trait.