Abstract：Dopamine receptor D1(DRD1) can promote or inhibit the secretion of prolactin in the birds' brain. It is associated with the reproductive system and highly expressed in the hypothalamus and pituitary. The experiment was designed to study of polymorphism of 5' flanking regulating of DRD1 gene on sexual maturity traits in cock (Gallus gallus), 140 W lines breeding from Poultry Institute, Chinese Academy of Agricultural Sciences were used in the experiment. The SNPs was detected by PCR-RFLP (cleaved amplification polymorphism sequence-tagged sites) and analyzed the association of polymorphisms sites with body weight, comb height 1, comb height 2 and comb length of cock at 77, 84 and 91 days of age. The results indicated that one mutation site was detected in 5' flanking regulating of DRD1 gene. Three genotypes (AA, AG and GG) were found at G-570A mutation locus at the distance of CDS-570 locus in 140 cocks by digesting the PCR product with MspⅠ. The relationship between DRD1 gene and the sexual maturity traits was analyzed by least squares linear model. The individuals with GG genotype had significant effect on the body weight (P＜0.05), and had no significant effect on the comb height 1, comb height 2 and comb length of cock at 77 days of age. At 84 days of age, the individuals with different genotype of body weight comb height 1, comb height 2 and comb length were not significant. The individuals with GG genotype had significant effect on comb height 1 and comb length (P＜0.05). The DRD1/883 promoter of DRD1 gene was amplified using PCR technology, inserted into the dual-luciferase reporter vector (pGL3-Basic) to construct pGL3-DRD1/883/promoter. 293T cell were co-transfected with a plasmid containing the pGL3-DRD1/883/promoter, pGL3-Basic and PRL-CMV, respectively. The activity of luciferase gene in 293T cell was testing using the Dual-Luciferase Reporter Assay kit. The results showed that the intensity ratio of firefly to sea renal luciferase of DRD1/883G prompter enhance 13.3 times than DRD1/883A promoter, showed high expression (P＜0.01). Thus it can be seen, GG was the most favorable genotype for early maturity traits in chicken. Individuals with DRD1/883G had higher levels of transcription. These results imply that DRD1 gene may have a certain effect on early maturity on chicken and provide a theoretical basis for the expression and function of DRD1 gene and breeding of high quality broiler.
