Characteristics of Intron 17 and Exon 18 of Leptin Receptor Gene in Nigerian Locally Adapted and Exotic Turkeys

Abstract

Leptin Receptor gene (LEPR) gene has been implicated as the activator of the JAK-STAT signaling pathway and plays an important role in regulating body energy storage and metabolism. Identification of Single nucleotide polymorphisms (SNPs) were carried out in intron 17 and exon 18 of LEPR gene in 200 turkeys comprising 100 each of Nigerian locally adapted and exotic (Nicholas White) turkeys. Blood samples for DNA extraction were collected at 20 weeks. DNA extraction was carried out using whole blood collected with Quick- DNA Miniprep Plus extraction kits by strictly followed the manufacturer’s protocol. The sequence data obtained were analyzed using GeneScan and Sequencing software (Applied Biosystems). The single nucleotide polymorphisms (SNPs) present in LEPR gene of the two turkey genotypes were identified using DnaSP 6 software. The allele frequency of each SNP, Heterozygosity (He) and Polymorphic information content (PIC) of the SNPs were calculated. Out of six SNPs identified in intron 17 of the turkey LEPR gene, four were found in local turkeys while all the six were found in exotic turkey. The major allele frequency of the SNPs ranged from 0.86 to 0.96. The SNP 28C>G in exotic turkey had the highest HE while SNPs 7T>G, 67A>T and 85G>C in local turkey had the least. The PIC ranged from 0.077 in local turkey to 0.211 in exotic turkey. In addition, ten SNPs were identified in exon 18 of the turkey LEPR gene, out of which eight were detected in local turkeys while seven were detected in exotic turkeys. The major allele frequency of the SNPs identified in exon 18 ranged from 0.54 in 602A>C in local turkey to 1.00 in 60T>G, 267A>G, 274A>G alleles that are fixed in both local and exotic turkeys. Also, SNP 602A>C in local turkey had the highest HE while incidentally SNPs 130G>C, 166G>A and 789G>A also in local turkey had the least heterozygosity. PIC discovered in exon 18 of LEPR gene ranged from 0.077 to 0.377 in local turkey. Intron 17 and exon 18 of LEPR gene is polymorphic in both Nigerian locally adapted and exotic turkeys and therefore could be used for further analysis to form a basis for genetic variation in growth in the two genotypes