Association of prolactin and prolactin receptor gene polymorphisms with economic traits in breeder hens of indigenous chickens of Mazandaran province

Abstract

Polymorphisms in 5'-flanking region of prolactin (PRL), exon 2 and exon 5 of prolactin receptor (PRLR) genes<br />and its association with growth and egg traits were examined in breeder hens of Mazandaran native fowls<br />breeding station. A single nucleotide polymorphism at site C-2402T and a 24 bp nucleotide sequence insertion<br />at situation -382 in 5'-flanking regions of PRL gene were identified. PCR amplification together with<br />Restriction Fragment Length Polymorphism (RFLP) and direct agarose gel electrophoresis were used to identify different genotypes at C-2402T and a 24 bp indel (insertion-deletion) at the site of -358 of PRL gene, respectively. Nucleotide substitution of C to T and a 24 nucleotides insertion (I) or deletion (D) in promoter<br />region of PRL gene resulted in three genotypes with the frequency of CC (0.10), CT (0.84), TT (0.06)<br />and II (0.39), ID (0.40), DD (0.21), respectively. There were no heterozygous females and only two genotypes A/A (0.54), B/B (0.46) and AA (0.72), BB (0.28) were identified in exon 2 and exon 5 of PRLR gene<br />using PCR-Single Strand Conformation Polymorphism (PCR-SSCP) and PCR-RFLP analyses, respectively. A<br />novel mutation consists of a BamHI restriction site found in the exon 5 of PRLR gene. The results showed<br />significant association between SNP in exon 2 with body weight at hatch, age at sexual maturity, and<br />between SNP in exon 5 and egg number. Individuals with AA genotype produced higher eggs than BB genotype (P<0.05). These results showed that the PRLR locus can be considered as a major gene that may<br />influence the production traits in chicken.