Genotypic Frequency of Calpastatin Gene in Atabi Sheep by PBR Method Shahram Nanekarani 1 , Saber Khederzadeh 2 and Amar Mohammadi Kaftarkari 3 1 Department of Animal Sciences, Broujerd Branch, Islamic Azad University- Broujerd, Iran E-mail: sh.nanekarani@gmail.com 2 Department of Biology, Varamin Pishva branch, Islamic Azad University- Varamin Pishva, Iran 3 Bandar gaz Branch, Islamic Azad University- Bandar gaz, Iran Abstract. Calpastatin have role in regulation muscle growth and meat tenderness after slaughter that its coding gene located on ovine chromosome 5. Studies have shown that this gene is polymorphic in many breeds of sheep and is related with weight gain and carcass traits. In this study blood samples were collected from 120 Atabi sheep located in northern and western Golistan of Iran. Genomic DNA was extracted from blood sample. Gel monitoring and spectrophotometer methods were used to determination quality and quantity of DNA. Exon and entron I from L domain of the ovine calpastatin gene was amplified to produce a 622 bp fragment. The PCR products were digested by restriction endonucleases MspI. Digested products were separated by electrophoresis on 2.5% agarose gel and visualized after staining with ethidium bromide on UV transillumination. The MspI digestion of the PCR products produced digestion fragments of 336 bp and 286 bp. Data analysis was done using PopGen32 software (ver.1.32). In this population, AA, AB, BB genotype have been identified with the 67.5, 27.5, 5.0% frequencies, respectively. The population was found to follow Hardy-Weinberg equilibrium. Keywords: Calpastatin gene, polymorphism, Atabi Sheep, PBR Method. 1. Introduction Genetic polymorphism in native breeds is a major concern considering the necessity of preserving genetic resources. It is very important to characterize genetically indigenous breeds (Bastos et al., 2001). Marker assisted selection is one of the new DNA based methods that improves accuracy and progress of selection in animal programmers'. Calpastatin (CAST) gene is located on the fifth chromosome of sheep and plays important roles in formation of muscles, degradation and meat tenderness after slaughter. The rate and extent of skeletal muscle growth ultimately depends mainly on three factors: rate of muscle protein synthesis, rate of muscle protein degradation, and the number and size of skeletal muscle cells. Recent studies have shown that calpain activity is required for myoblast fusion [Balcerzak 1995, Barnoy 1997] and cell proliferation in addition to cell growth [Mellegren 1997]. The calpain system may also affect the number of skeletal muscle cells (fibres) in domestic animals by altering rate of myoblast proliferation and modulating myoblast fusion. A number of studies have shown that the calpain system is also important in normal skeletal muscle growth. Increased rate of skeletal muscle growth can result from a decreased rate of muscle protein degradation, and this is associated with a decrease in activity of the calpain system, due principally to a large increase in calpastatin activity (Goll et al. 1998). Calpastatin, which is an endogenous inhibitor (ca +2 dependent cysteine proteinase), plays a central role in regulation of calpain activity in cells (Murachi et al., 1981;Murachi, 1983; Forsberg et al., 1989) and is considered to be one of the major modulators of the calpains. Therefore, calpastatin may affect proteolysis of myofibrils due to regulation of calpain, which can initiate postmortem degradation of myofibril proteins (Goll et al., 1992; Hufflonergar et al., 1996). At the 189 2011 International Conference on Food Engineering and Biotechnology IPCBEE vol.9 (2011) © (2011)IACSIT Press, Singapoore