Genetic Polymorphism in the Promoter and 5 ́ UTR of HSP-70 Gene in Three Strains of Indigenous Tswana Chickens and Commercial Broilers

Abstract

The current study was conducted to investigate sequence polymorphisms in the promoter, 5 ́untranslated regions (UTR), and partial exon regions of chicken HSP-70 gene in the normal (n = 24), naked neck (n = 22), and dwarf (n = 12) strains of indigenous Tswana chickens relative to the commercial broiler chickens (n = 20). Genomic DNA extracted from the whole blood of the three strains of indigenous Tswana chickens and the commercial broilers were amplified using PCR and sequenced. The PCR amplicons comprised a 210 bp promoter region, a 112 bp 5 ́UTR, and a 463 bp partial exon of the chicken HSP-70 gene. Multiple sequence alignments of the partial sequences of chicken HSP-70 gene in indigenous Tswana chickens and the commercial broilers revealed no polymorphisms in the promoter region, two SNPs in the 5 ́UTR (A303G and G309A) and another two SNPs (G427 and A628G) in the partial exon sequence of chicken HSP-70 gene. The SNP G427A was unique to the normal strain and the other three SNPs were common to all the four chicken strains studied. The identified four SNPs linked up in individual chickens resulted in a total of seven different haplotypes in the studied four chicken populations. A total of seven different haplotypes were found in indigenous Tswana chickens and only two haplotypes were found in the commercial broilers. More nucleotide (4SNPs vs 3 SNPs) and more haplotype diversity (7 haplotypes vs 2) were thus found in indigenous Tswana chickens, compared to the commercial broilers in the partial sequence of HSP-70 gene.