SEQUENCE ANALYSES OF INSULIN-LIKE GROWTH FACTOR 1 GENE IN NIGERIAN INDIGENOUS AND ARBOR ACRE CHICKENS

The chicken Insulin-like growth factor 1 (IGF1) is a candidate gene for growth, body composition and metabolism, skeletal characteristics and growth of adipose tissue and fat deposition in chickens. It is mapped to 165.95 cM on chromosome 1 and composed of four exons and three introns, spanning more than 50 kb. Genomic DNA was extracted from blood samples collected from the experimental birds using Qiagen DNA extraction kits. Polymersae chain reaction (PCR) was carried out using established primers. The PCR amplicon involving 5’untranslated region were sequenced. The sequences were analysed to identify polymorphisms, their genetic diversities and evolutionary relationships among three strains of Nigerian indigenous chickens [Frizzle Feathered (7), Normal Feathered (19) and Naked Neck (19), and the Arbor Acre broiler chicken (17)]. Nucleotide sequences generated were edited and aligned using Codon Code Aligner. Diversity analysis was done using DnaSp while MEGA6 software was used to plot phylogenetic tree using maximum likelihood method. A total of nineteen single nucleotide polymorphisms (SNPs) were detected from 560 bp portions of the 5’UTR among the four chicken populations studied with none detected in the Frizzle feathered chicken. The Naked neck chicken had the highest number of SNP’s (13), haplotypes (6), haplotype diversity (0.778), nucleotide diversity (0.00487), average number of nucleotide differences (2.725), highest number of polymorphic (segregating) sites (13), parsimony informative site (5) and singleton variable site (8). The Naked neck chicken therefore had the highest rate of mutation and degree of allelic variation compared to other chicken strains used in this study. The phylogenetic tree showed that small genetic differentiation exists among the chicken populations studied. Some of the SNPs are newly discovered; hence, association between these alleles and productive traits in Nigerian native chickens is desirable in future studies.