ABSTRACT
Genotypes for melatonin receptor type 1A [MTNR1A] and Calpastatin [CAST] were determined by enzymatic digestion of PCR products and Calpain [CAPN] genotype detected by PCR-SSCP method in Iranian Karakul sheep. Blood samples were collected from 100 purebred Karakul sheep. The extraction of genomic DNA was based on guanidinium thio-cyanate-silica gel method. PCR amplicons were digested with restriction enzymes Mnll and Mspl for MTNR1A and CAST genes, respectively. The MTNR1A locus had two alle-les with frequencies of 0.79 for [+] and 0.21 for [-] alleles. Allelic frequencies for CAST locus were 0.85 for M and 0.15 for N. In addition, Calpain had two alleles A and B with respective frequencies of 0.79 and 0.21. The observed het-erozygosity values for MTNR1A, Calpastatin and Calpain locus were 0.42, 0.29 and 0.35, respectively. The X[2] test confirmed the existence of Hardy-Weinberg equilibrium for the three loci in the population. The data showed a large variation in studied genes. The genetic polymorphism could be regarded as useful tool for selection programs based on marker- assisted selection between different genotypes of those loci