DNA Polymorphism within <i>LDH-A</i> Gene in Pigeon (<i>Columba livia</i>)

Calcium/Calmodulin-Dependent Serine Protein Kinase (CASK) Gene Polymorphisms in Pigeons

Calcium/calmodulin-dependent serine protein kinase (CASK) is an multidomain protein involved in tissue development and cell signalling. In skeletal muscle, it is involved in the development of neuromuscular junctions. The participation of a pigeon in racing is a great physical effort that causes many changes in the skeletal muscles. Thus, the purpose of the study was to detect the nucleotide sequence variability in the calcium/calmodulin-dependent serine kinase (CASK) gene in domestic pigeons (Columba livia domestica) and assess the potential impact of DNA polymorphisms on the flight performance of pigeons. The research included a total of 517 individuals. DNA was extracted from the blood. A DNA fragment from nucleotides 8689 to 9049 of the CASK (NW_004973256.1 sequence) of six unrelated pigeons were sequenced. One of the detected polymorphic sites (g.8893G > A), located a very close to the start codon, was selected for genotyping in all individuals. The association studies included a total of 311 young homing pigeons that participated in racing competitions. The homing pigeons showed higher frequencies of the AA genotype than non-homing ones (p < 0.05). In rock pigeons only the GG genotype was found. Further research could confirm the functionality of the CASK g.8893G > A SNP in shaping the racing phenotype of pigeons, and the AA genotype could be useful as a selection criterion in pigeon breeding.

Development and Validation of KASP Assays for the Genotyping of Racing Performance-Associated Single Nucleotide Polymorphisms in Pigeons

Pigeon racing's recent upturn in popularity can be attributed in part to the huge prize money involved in these competitions. As such, methods to select pigeons with desirable genetic characteristics for racing or for selective breeding have also been gaining more interest. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) for genotyping-specific genes is one of the most commonly used molecular techniques, which can be costly, laborious and time consuming. The present study reports the development of an alternative genotyping method that employs Kompetitive Allele Specific Polymerase Chain Reaction (KASP) technology with specifically designed primers to detect previously reported racing performance-associated polymorphisms within the LDHA, MTYCB, and DRD4 genes. To validate, KASP assays and PCR-RFLP assays results from 107 samples genotyped for each of the genes were compared and the results showed perfect (100%) agreement of both methods. The developed KASP assays present an alternative rapid, reliable, and cost-effective method to identify polymorphisms in pigeons.

Application of PCR-HRM method for microsatellite polymorphism genotyping in the LDHA gene of pigeons (Columba livia)

High-resolution melting (HRM) is a post-PCR method that allows to discriminate genotypes based on fluorescence changes during the melting phase. HRM is used to detect mutations or polymorphisms (e.g. microsatellites, SNPs, indels). Here, the (TTTAT)_3-5 microsatellite polymorphism within intron 6 of the LDHA gene in pigeons was analysed using the HRM method. Individuals (123 homing pigeons) were genotyped using conventional PCR. Birds were classified into groups based on genotype type and the results were tested by qPCR-HRM and verified using sequencing. Based on the evaluated protocol, five genotypes were identified that vary in the number of TTTAT repeat units (3/3, 4/4, 3/4, 4/5, and 5/5). Sequencing have confirmed the results obtained with qPCR-HRM and verified that HRM is a suitable method for identification of three-allele microsatellite polymorphisms. It can be concluded that the high-resolution melting (HRM) method can be effectively used for rapid (one-step) discrimination of the (TTTAT)_3-5 microsatellite polymorphism in the pigeon’s LDHA gene.

LDHA gene is associated with pigeon survivability during racing competitions

Pigeon racing is a popular sport worldwide. Pigeons are under continuous selection to improve speed, spatial orientation, and endurance during long flights. However, numerous genetic and non-genetic factors affect survivability and homing ability, making such traits difficult for breeders to control. Polymorphisms in the lactate dehydrogenase A gene (LDHA) likely affects pigeon racing and homing abilities, due to its role in physical and mental performance. Additionally, the adenylate cyclase activating polypeptide 1 gene (ADCYAP1) has been associated with physiological and behavioral shifts that occur during avian migration. In this study, we examined the association between LDHA and ADCYAP1 genotypes with pigeon survivability during racing competitions. Survivability was evaluated through the estimated breeding value (EBV) of each individual's total race distances during its athletic life. ADCYAP1 was not polymorphic among our samples, while LDHA genotypes were significantly associated with deviated EBV values of longer total race distance; individuals carrying the S+ genotype had higher EBV (i.e., greater survivability). Thus, the LDHA locus might be useful for marker-assisted selection, empowering breeders and trainers to maximize pigeon quality. Moreover, data obtained from breeding will also improve our understanding of the genetic mechanism underlying navigation and flight for wild migrating bird species.