IntroductionTurkey's proximity to domestication centers, along with its climate, topographical pattern, and agricultural structure that is formed according to plant cover, has created an appropriate environment for sheep breeding. Therefore, there are many sheep breeds in various regions and territories (1,2). Although there are many varieties and crossbred populations of sheep breeds in Turkey, 20 sheep breeds have been officially registered by the Ministry of Food, Agriculture, and Livestock (3). Even though Gökçeada (GA), Kıvırcık (KIV), Karacabey Merino (KM), and Sakız (SZ) sheep breeds, which are raised in the western Anatolian and Marmara regions, have a low percentage of native sheep population, each breed has certain significant characteristics. SZ sheep, known for their high fertility and milk production, and GA sheep, known for their milk production and high lamb survival rate, are raised along the coastline of the Aegean region. KIV and KM sheep breeds are known for their meat quality, wool, and meat production and are raised in western Turkey. For the purpose of improving the meat quality and fertility of the sheep population in western Turkey, the SZ and KIV breeds are commonly used in crossbreeding (4).Molecular genetic methods for identifying genetic structure and diversity in farm animals have shown a rapid development in recent years and have become widely used. Various molecular genetic methods have been developed for this purpose. Microsatellites that are specific to DNA regions are more widely used than other methods (5).This study aims to determine the genetic structure of GA and SZ sheep breeds, which are bred on the coastline of the Aegean region, and that of the KIV and KM sheep breeds, which are commonly bred in the Aegean and Marmara regions, by means of microsatellites. The information obtained from this study is based on microsatellite markers and will clarify the genetic relationships between these sheep breeds. It will also be helpful for determining current and future breeding programs and breed management and conservation strategies. Materials and methods Animal resources and DNA isolationThe animal material of the study consisted of a total of 250 animals belonging to GA, KIV, KM, and SZ sheep populations bred in the Aegean and Marmara regions. The origins and sample sizes of these 4 breeds are presented in Table 1. A DNA isolation kit (Applied Biological Materials Inc., Canada) was used for DNA extraction from blood samples.

Bovine spongiform encephalopathy (BSE) of the cattle is the outstanding disease among other transmissible spongiform encephalopathy (TSEs). It can be transmitted from the cattle to a human and causes a new variant of the Creutzfeldt-Jakob disease (CJD). It is known that prion protein coding gene (PRNP) plays a major role in the TSE susceptibility or resistance in some species. Recent researches demonstrated that the insertion (in) and deletion (del) polymorphisms within promoter and intron 1 region of the PRNP related to BSE susceptibility in cattle. In contrast to cattle, BSE has never been reported in water buffalo; hence, PRNP polymorphisms may be an explanation for buffalo resistance to BSE. The aim of this study was to evaluate allele, genotype, and haplotype frequencies of the PRNP promoter and intron 1 insertion/deletion (indel) polymorphism in healthy Anatolian, Murrah, and Murrah × Anatolian crossbred buffaloes. According to our findings, there were no deletion alleles at two mentioned loci. All studied buffaloes were monomorphic and have carried in/in haplotypes which are considered as the most resistant genotype to BSE.

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