Int. J. Pharm. Sci. Rev. Res., 30(1), January – February 2015; Article No. 60, Pages: 340-344 ISSN 0976 – 044X International Journal of Pharmaceutical Sciences Review and Research Available online at www.globalresearchonline.net © Copyright protected. Unauthorised republication, reproduction, distribution, dissemination and copying of this document in whole or in part is strictly prohibited. © Copyright pro 340 Saleha Y. M. Alakilli Department of Biology, King Abdulaziz University, Jeddah/ Northern Border University, Arar, Saudi Arabia. *Corresponding author’s E-mail: salakilli@yahoo.co.uk Accepted on: 20-11-2014; Finalized on: 31-12-2014. ABSTRACT With the recent advances in molecular biology techniques, a great interest focused towards the improving livestock production in general and meat production in specific. In the present study is to identify the genetic polymorphism of calpastatin and callipyge genes (CAST and Clpy) related to meat production in two Saudi sheep breeds (Najdi and Harri). The detection was done using the restriction fragment length polymorphism for the polymerase chain reaction products (PCR-RFLPs). Genomic DNA was isolated from 20 animals from each breed; The PCR products were digested with MspI restriction enzyme for calpastatin gene and FaqI restriction enzyme for callipyge gene. The results indicated the presence of polymorphism in the callipyge gene was detected homozygous genotype AA – 1.00 only in the two breeds understudy. The heterozygous genotype AG and homozygous genotype GG was not detected. Calpastatin locus digested with MspI had two genotypes MM and MN. The highest allelic frequency was for allele M allele but homozygous genotype NN has not been observed. The CAST locus had two genotypes MM (0.64 and 0.26 from Najdi and Harri) and MN (0.36 and 0.74 from Najdi and Harri), but homozygous genotype NN has not been observed. It may be concluded that CLPG locus is a monomorphic for population sheep kept in Saudi. The locus of CAST gene is polymorphic for breeds of sheep involved Najdi and Harri. Najdi sheep breed showed the highest observed heterozygosity for CAST gene. Keywords: Sheep, PCR-RFLP, Calpastatin gene, Callipyge gene. INTRODUCTION t the present time, the consumers demand for sheep meat is not focused on quantitative traits only, but also qualitative traits of meat too. Animal breeders could accelerate the rate of genetic improvement attained in carcass composition and meat quality traits through the application of gene-assisted selection (GAS), based simply on incorporating some candidate genes in traditional breeding programs 1 . The Najdi or Nejdi is a breed of domestic sheep native to the Najd region of the Arabian Peninsula. Though it is primarily raised in Saudi Arabia, Nadji sheep are also present in Kuwait, Jordan, Oman, and Iraq 2 . The Najdi has a distinctive appearance that has even been celebrated in Saudi “sheep beauty pageants” not unlike livestock shows and sales in the West. They are a very tall breed, averaging 76-86 centimeters (30-34 inches) in height at the withers 2 . They have long, Roman nosed faces with drooping ears. Ewes are polled and rams may be either polled or have scars. They are generally black with white faces and white on the legs and tail. Top Najdi ewes can sell for 20,000- 30,000 Saudi riyals ($5,300-$8,000 USD), while rams which can sire many more offspring can fetch hundreds of thousands 2 . Najdi are highly adapted to life in desert conditions, though it is less drought tolerant than some breeds, such as the Awassi 3,4 . Though its meat may be consumed locally, it is especially valued for its milk and long, straight wool. There are many of published articles on two genes associated with meat-related traits in varied sheep breeds, CAST and Callipyge genes 5 . Calpastatin (CAST) gene is located on the fifth chromosome of sheep and plays important roles in formation of muscles, degradation and meat tenderness after slaughtering 6 . It was also proved that there is a relationship between polymorphism in the calpastatin gene in sheep and slaughter traits such as lamb’s body weight at birth and its growth rate until weaning 7 . Associations between variation in CAST and carcass and meat quality traits in sheep, there was also a genetic variation in the CAST gene 8-11 The Callipyge (CLPG) gene is most documented gene for double muscle in sheep which causes a postnatal muscle hypertrophy that is localized to the pelvic limbs and loin 12 . The mutation cognizant of unique muscling phenotype in sheep was first discovered in 1983 in Oklahoma in Dorset breed. The locus of CLPG gene was mapped to the telomeric region of ovine chromosome 18 13 . The CLPG gene has unique inheritance pattern, which has been termed as polar overdominance 14 . The term polar overdominance was used to describe the genetic model in which only heterozygous individuals that were receiving the newly identified allele from their sire expressed the unique phenotype 14 . Callipygephenotypic effects were previously estimated in heterozygous lamb but the mutant CLPG allele have to be inherited from sire and normal allele have to be inherited from dam. The others combination of allele can be classified as non carrier lambs with normal phenotype 15 . Analysis of Polymorphism of Caplstatin and Callipyge Genes in Saudi Sheep Breeds Using PCR-RFLP Technique A Research Article