SNPs In 5’ Regulatory Region Of Shouguang Chicken AANAT Gene And Their Association With Laying Trait

Mainly formed by pineal gland of mammals, melatonin(MLT) is a kind of indol e derivatives with a wide range of biological activities. Four steps are needed to synth esize MLT from tryptophan, hydroxylation, decarboxylation, N2-acetylation and methyla tion, oxygen melatonin. The synthesis procedures are same from amphibians and reptil es to birds and mammals. AANAT(Serotonin- N- acetyl transferase), the rate-limitin g enzyme and HIOMT, the key enzyme play important parts of the procedure. By ana lyzing the correlation between 5 ’control region polymorphism of AANAT and chicken egg production traits, this study intends to detect meaningful molecular markers as an auxiliary tool for breeding laying hens. The research may also help to improve the molecular mechanism of MLT activity.The experimental material is Shouguang Chicken. By using monoclonal sequencin g the fragments of 5’ control region or AANAT, where polymorphism loci may exist,were amplified. With the direct sequencing technique on a large group of Shouguang Chicken to detect the SNPs, we then analyzed the correlation with these SNPs and th e egg production traits. The results are as followings:There are 24 SNPs on the 5’ control region of AANAT, with 15 transition, 7 tr ansversion and 2 insertion. 8 loci(-853,-803,-623,-619,-561,-522,-477,-210) have a sign ificant influence on egg production performance(P < 0.05), while others do not. 4 of the 8 are low polymorphic sites, with great difference of frequencies among each oth er. The G base at-803 accelerates the first egg day by 2.5 days, improving the early egg number by 1.6 than the T base by additive effect and dominant effect. Compare d with the A base,the T base at-561 improves the middle egg number by 0.9 with additive effect significantly, and improves total egg number by 4 with significant addit ive effect and dominant effect. Compared with the G base,the A base at-522 improv es the late egg number by 1.5 and improves total egg number by 5.4 with significant additive effect and dominant effect. The A base at-210 accelerates the first egg day by 2.9 days, improving the total egg number by 5.8 than the C base.The loci-708、-615 were linked with four haplotypes in the population. Compared with TG, haplotype TA postponed the age of first egg by 10.3 days significantly(P<0.05). The loci-619、-595 were linked, with four haplotypes in the population. Comp ared with GT, haplotype GG improved middle egg number by 10.6 significantly(P<0.05). There is significant interaction effect between haplotype AC and GC, decreasing t he early and middle egg number. The loci-546、-210 were linked, with four haplotyp es in the population. Compared with TA, haplotype CC accelerated the age of first eg g by 4 days significantly(P<0.05); haplotype CA decreased middle egg number by 6.8 significantly(P<0.05).This study detected some potential molecular markers, provided a reference for ch icken genetic improvement and breeding as well as the molecular mechanisms of MLT receptor on chicken breeding performance.