Genetic Variation and SNP of Tyrosinase Gene Among Some Camel Breeds Reared in Egypt

Sally S. Alam, Heba A.M. Abd El-Kader, Sekena H. Abd El-Aziem and Othman E. Othman*

Department of Cell Biology, National Research Centre, Dokki, Egypt.

ABSTRACT: Tyrosinase is a key enzyme in the metabolic pathway leading to coat color pigmentation. Mutations in the tyrosinase (TYR) gene are responsible for the albino phenotype in mammals and chicken. Loss of tyrosinase mRNA expression prevents melanin synthesis, thereby causing albinism. The objective of this study was to detect the genetic variations and SNPs of tyrosinase gene among five camel breeds reared in Egypt; Sudany, Somali, Mowaled, Maghrabi and Falahy. Genomic DNA was extracted from blood samples of camels belonging to the five tested breeds and the genotyping of TYR was studied using PCR-RFLP technique. The amplified fragment of camel TYR exon 1 at 474-bp was digested with the restriction enzyme DdeI. The result showed the appearance of three different genotypes; CC, CT and TT in the tested breeds with significant differences in genotype and allele frequencies between these breeds. The camels in Somali, Falahy and Sudany breeds had slightly higher T allele frequency (0.38, 0.36 and 0.33, respectively) than those in Maghrabi and Mowaled camels (0.18 and 0.27, respectively). The genotype TT was detected only in Somali, Falahy and Sudany camels. The overall genotype frequencies for all breeds obtained were 0.06, 0.49 and 0.45 for TT, TC and CC, respectively. The sequence analysis declared the presence of a SNP (C/T) at position 135 in the amplified fragment which is responsible for the destruction of the restriction site C^TCAG and consequently the appearance of two different alleles C and T. The nucleotide sequences of camel TYR alleles C and T were submitted in GenBank database and have accession numbers: KP193960 and KP193961, respectively. It is concluded that only one SNP C/T was detected in TYR gene among the five tested camel breeds and this nucleotide substitution can be used as a marker for the genetic biodiversity between camels breeds reared in Egypt. Also, due to the possible association between TYR gene with coat color pigmentation, we can used its polymorphism for MAS in breeding programs for targeted color camels.

KEYWORDS: Camel breeds in Egypt; TYR; PCR; RFLP; SNPs

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