Laying Curve Fitting Of Jining Bairi Chicken And Polymorphism Analysis Of 5' Regulatory Region Of ASMT Gene

Melatonin(Mel)is a steroid hormone with a variety of biological effects,mainly synthesized in the pineal gland.It has the functions of regulating the circadian rhythm,endocrine,and controlling the seasonal reproduction of animals.ASMT,acetyl serotonin methyltransferase,is a key enzyme involved in melatonin synthesis.This study aimed to study the transcriptional regulation of chicken ASMT gene and its association with egg production traits at the molecular level,laying the foundation for breeding work.The experiment used Jining Bairi Chicken as the research material.Firstly,the curve analysis of the egg production rate and cumulative egg production number of Jining Bairi Chicken was carried out.Then,the5'RACE was used to determine the transcription initiation site of ASMT gene,and its 5'regulation was amplified.The region was searched for its core promoter region;finally,the SNPs of the 5'regulatory region of the ASMT gene were searched and correlated with the egg production traits.The main findings are as follows:(1)Yang Ning model had the best fitting effect on the egg production rate of Jining Bairi chicken,R~2 reached 0.990,higher than Wood model(R~2=0.699),compartment model(R~2=0.891)and cubic equation(R~2=0.887).The three nonlinear models have a good fit to the cumulative number of eggs laid in Jining Bairi Chicken,and the fitting degree is more than0.99.The Von Bertalanffy model has the best fitting degree,reaching 0.999;the Gompertz model is second,R~2 is 0.997.The Logistic model is the lowest.R~2 is 0.990.(2)The transcription initiation site of the ASMT gene was determined,and its mRNA5'UTR was 19 bp long,the sequence was GCCTCAATACTAAAGGAAG,and the transcription start site was base G.(3)The promoters of the ASMT gene were deleted and the vector was transfected into three kinds of cells.The luciferase activity was analyzed and the-272~-3 was used as the core promoter region.Bioinformatics analysis of this region revealed that there are multiple transcription factor binding sites such as Sp1,GATA-1,Oct-1,and NF-1.(4)A total of 32 SNPs were detected in the 5'regulatory region of the ASMT gene of Jining Bairi Chicken,and the polymorphism was extremely abundant.Two of the loci were low polymorphism,and the rest were moderate polymorphism.The-672 locus was significantly associated with the total number of eggs laid(P<0.05),and the mode of action was dominant.The total number of eggs produced by the GG type at this locus was significantly 7.41 more than that of the GA type,and 2.96 more than the AA type.The-550locus was significantly associated with the number of eggs laid in the previous period(P<0.05),and the mode of action was additive.The number of eggs laid in the pre-AA period was 3.96 and 3.52,respectively,compared with GG and GA.The-254 locus had a significant effect on the age of onset and the number of eggs laid in the previous period(P<0.05).The age of TT-type individuals was earlier than that of CC and CT,and the number of eggs laid in the previous period increased by 4.39 and 3.8,respectively.One.The mode of action of this site on the age of onset was dominant and additive,both significant(P<0.05).Among them,the-254 locus is located in the core region of the promoter of the ASMT gene.(5)Analysis of haplotypes of all SNP loci revealed that:-786,-550,-529,-254 were linked,and three haplotypes of CGCC,CGTC,and TATT were constructed.However,the association analysis of each haplotype with egg production traits was not significant.In summary,the Yang Ning model and the Von Bertalanffy model have the best fitting effect on the egg production rate and cumulative egg production of Jining Bairi chicken;the transcription start site of chicken ASMT gene is base G,-271~-3 is the core promoter region of ASMT gene;32 SNPs were detected in the 5'regulatory region of ASMT gene in Jining Bairi chicken,and-672,-550 and-254 sites had significant effects on egg production traits.Among them,the-254 locus was located in the core region of the promoter,which was significantly correlated with the number of days of production and the number of eggs laid in the early stage.