Study of Genetic Resistance to Scrapie in Sheep of the Gene Pool Herd of the Southern Meat Breed and in Their First Generation (F1) Crossbreeds with Katumskaya Breed by the Prion Protein Gene (PRNP)

Polymorphism of Prion Protein Gene and Evaluation on Genetic Risk for Scrapie in Three Native and One Introduced Breed in the Republic of North Macedonia

Abstract Transmissible spongiform encephalopathy in sheep is known as scrapie. Polymorphisms at codons 136, 154, and 171 of the prion protein (PRNP) gene are associated with resistance or susceptibility to the disease. Based on allele combinations, sheep are classified into five genetic risk groups. The aim of this study was to determine the distribution of PRNP gene polymorphisms and assess the genetic susceptibility to scrapie among native and introduced sheep breeds reared in North Macedonia. A total of 309 unrelated animals from three native Pramenka-type sheep breeds, Karakachanian (n=92), Ovchepolian (n=91), and Sharplaninian (n=34), and one introduced breed, Awassi (n=92), were genotyped. The Awassi and Sharplaninian breeds were dominated by the ARQ/ARQ genotype (R3). In Karakachanian sheep, the ARR/ARQ genotype (R2) was most frequent, while Ovchepolian sheep showed equal predominance of ARR/ARQ (R2) and ARQ/ARQ (R3). High-risk genotypes (R4 and R5) were detected only in the Ovchepolian and Sharplaninian breeds. The ARQ allele was the most frequent in Awassi (0.7609), Ovchepolian (0.4945), and Sharplaninian (0.5000), whereas the ARR allele predominated in Karakachanian sheep (0.5772). The VRQ allele was detected only in the Ovchepolian and Sharplaninian breeds. These findings demonstrate genetic differences among the studied sheep populations and provide valuable information for breeding strategies aimed at increasing resistance to scrapie while conserving breed diversity.

DNA MARKERS FOR EVALUATING THE ADAPTATION POTENTIAL OF RABBITS AND FUR-BEARING ANIMALS

Modern breeding of agricultural animals has transitioned from phenotype-based selection to high-precision genomic prediction based on hundreds of thousands of DNA markers. This has not only accelerated the development of breeds with target traits but also enhanced their adaptability and stress resistance through the design of balanced selection programs. In this context, the present work involved the selection and validation of various DNA markers associated with adaptation potential in rabbits (Oryctolagus cuniculus) and fur-bearing animals (using the sable Martes zibellina as an example). Studies were conducted using PCR and real-time PCR. In the population-genetic study of female sables (n=9, yearlings born in 2023; n=5, two-year-olds born in 2022; n=7, born before 2022), highly polymorphic markers ((ACC)6G, LTR-BERV-K1) were identified, demonstrating high discriminatory power in analyzing differences between animal generations. In the study of feed additive effectiveness in rabbits (n=12, Rodnik cross), reduced expression of metabolic genes g6pd and slc15a1 was observed when using a vitamin-mineral premix during the fattening period. The micronucleus test revealed the potential genome-destabilizing effect of the premix on blood cells, despite the absence of a statistically significant effect on body weight gain. In the behavior genetics study (n=8, rabbits of the Soviet Chinchilla and White Giant breeds), breed and sex differences in the expression of glutamatergic system genes grik3 and gria2 were discovered, opening prospects for selection aimed at reducing aggression in captive animal populations. The proposed approaches create new opportunities for fur farming and rabbit breeding through targeted selection of DNA markers to control genetic variability across generations and the functional activity of key metabolic network components.

Characteristics of genetic resistance to Maedi-Visna in sheep breeds raised in Russia

Relevance. Small Ruminant Lentiviruses (SRLVs), including the Visna-Maedi Virus (VMV) in sheep, induce chronic progressive inflammation primarily targeting the nervous system, lungs, mammary glands, and joints. These viruses exhibit significant genetic variability, leading to a lack of effective therapies or vaccines at an affordable cost. Foreign research has identified breed-specific variations in genetic resistance to these pathogens, but such comparative data remain largely unexplored for Russian sheep breeds. A reliable DNA marker of genetic resistance to VMV infection is the ovine transmembrane protein 154 (TMEM154) gene. This study aimed to evaluate the allelic diversity among different Russian sheep breeds through targeted SNP within the TMEM154 gene linked to genetic resistance. Methods. The study utilized biological samples (tissues) of sheep maintained at the Ladozhsky PZ and from the biobank repository titled “Genetic Materials Bank of Domestic and Wild Animals.” To identify specific mutations correlated with resistance to VMV, fragments encompassing the target SNP (OAR17_5388531) within the TMEM154 gene were amplified via RT-PCR. Results. Analysis of TMEM154 polymorphisms uncovered two distinct alleles (C and T) along with their corresponding genotypes: TT, CT, and CC. Genotype distributions associated with resistance to the Visna-Maedi virus across eighteen diverse Russian sheep breeds have been documented.

Analysis of Inbreeding, Population Structure, and Genetic Diversity in the Kumamoto Sub-Breed of Japanese Brown Cattle

Simple Summary The Kumamoto sub-breed of Japanese Brown cattle is a local beef cattle population in Japan. It is facing increasing inbreeding and a declining effective population size because of the intensive use of a limited number of elite sires. This study used genetic marker information from 811 cows to evaluate inbreeding, describe the genetic structure of the population, and identify genetic subpopulations that may help to preserve genetic diversity. We found that segment-based measures gave consistent information about inbreeding. The main genetic differences among animals were not explained by where they were raised, but were closely related to their paternal background. Among the identified subpopulations, we found that the subpopulation mainly associated with the Haru-yama-to/-sakae sire background contributed most to overall genetic diversity and showed the lowest level of genomic inbreeding. These results suggest that individuals from this subpopulation may be useful for breeding designing aimed at controlling inbreeding and maintaining genetic diversity in the Kumamoto sub-breed.

Genotyping the self-incompatibility locus of wild and cultivated Brassica using NGS technologies: application to the evaluation of mate limitation in the endangered species Brassica insularis

Optimization of SCoT and iPBS-Retrotransposon Marker Systems for PCR-Based Genetic Analysis in Alfalfa (Medicago sativa L.)

The correct selection and appropriate optimization of molecular markers and primers used in genetic diversity studies are crucial for the unveiling of true polymorphism among genotypes and to make sure that the data obtained can be used effectively in breeding programs. Two important molecular marker systems that are widely used in genetic diversity analyses are SCoT and iPBS-retrotransposon markers due to their PCR-based structures and high discriminatory ability. Optimization of these markers is of high importance in alfalfa, which has a complex, polyploid, cross-pollinated genome structure. Alfalfa is not only among the most important forage crops of the world but also a strategic agricultural crop that needs continuous development because of its economic value and environmental advantages. Thus, genotype identification, population structure characterization, and determination of genetic relationships between populations constitute the basic research areas of the sustainable breeding efforts. In the present study, six alfalfa genotypes collected from distinct geographical regions of Turkey and representing the gene pool, together with two commercial varieties, were used as plant materials. Different DNA volumes were tested to find the optimal template DNA amount in the PCR amplification of the SCoT and iPBS-retrotransposon marker systems. The conditions determined after optimization were validated by screening with different SCoT and iPBS primers. The obtained results provide a reliable and reproducible methodological framework for studies on genetic diversity, population structure, and breeding in alfalfa.