| Prolactin (PRL), secreted from anterior pituitary, plays extensive roles in reproduction, growth, and immunology in animals. In avian, PRL is especially crucial for reproduction traits such as broodiness and thus for egg production. PRL need to combine its receptor (Prolactin Receptor,PRLR), act on target cell with the help of PRLR to promote target gene to expression. PRL and PRLR will bring reproduction handicap of creature with gene mutation or knock out; Follical-stimulate hormone(FSH) is a pituitary glycoprotein gonadotropin that is Composed of a-subunit and the specificβ-subunit, hCG, LH and TSH provided with a-subunit together in the same species. It plays a key role in hypo-thalamicgonad axis; The estrogen receptor(ESR) is a member of the nuclear receptor superfamily, including two subunits, estrogen receptor alpha(ESRa) and beta(ESRβ).a-subunit maintains natural reproduction function, andβ-subunit maintains natural efficiency ovulation. it affects the development of follicle in the reproduction cycle of female vertebrate.Considering the association of PRL,PRLR,FSHβand ESRa with chicken reproductivity, the PRL,PRLR,FSHβand ESRa genes were selected as candidates to screen the nucleotide variation by means of PCR-RFLP and PCR-SSCP protocols and analyze the association of polymorphisms with early egg reproduction.1 Polymorphisms in PRL and PRLR gene and association with egg production traitsA 24 bp insertion/deletion mutation, 5'-GACAAGAAGAGACAAGACAAGGAA-3', was identified in the promotor-378～-355bp (GenBank accession no. AB011438) of PRL gene,and detected a SNP(A-269G) in TaiHu chicken. The pure insertion genotype was not detected in the blue eggshell chicken with 80% deletion (AA genotype),and only one pure insertion genotype(BB) in TaiHu in this study. There are two loci (4198bp和4169bp) of HaeⅢenzyme cuting, 4198bp can be cut entiretily,but 4169bp only partly.Three genotype were detected in this site,and there were insert sequences in some individuals. Association analysis of early egg production traits showed that age at first egg of 5'flanking regulation region in blue eggshell chicken was significant difference between AA and AB (P＜0.05), moreover,the egg number at 36 weeks of genotype AA was higher than that of AB in PRLintron2 (P＜0.05),and the age of first egg was also significant difference between AA and AB.Whereas,there were not significant difference in PRL loci of TaiHu chicken (P＞0.05),and the difference of 20 weeks egg number after the age at 50% egg was five eggs. It is obvious that PRL influence early egg production traits comparatively, we need to study morely when we think PRL gene is important to the reproduction of chicken. Nucleotide variations were identified in exon 3 and 6 of PRLR gene respectively. A single nucleotide polymorphism (SNP), A9026G (GenBank accession no. AY237377), in exon 3 of PRLR was detected, which led to a nucleotide transition in the 5'-untranslated region (5'-UTR) of PRLR cDNA. The G14820A (GenBank accession no. AY237376), a synonymous mutation, was also detected in exon6 of the PRLR. PRLR3 and PRLR6 did not influence egg production traits (exclusion early average weight of egg) including age at first egg, egg index and early egg number (P＞0.05).2 Polymorphisms in FSHB gene and association with egg production traitsThe SSCP detection of PCR products showed that FSHβpro site was polymorphismic in two population. Six nucleotide variation at G-494A, T-470A, A-464G,-450A insertion, A-405G and A-361G,were identified in promotor region of TaiHu chicken;Three nucleotide variation at A-464G,-450A insertion, A-405G,were identified in promotor region of blue eggshell chicken,three genotype. In FSHBexon3 locus, there was not polymorphismic in TaiHu,and three genotypes in blue eggshell chicken. The polymorphismic sequences were detected the SNPs. A SNP,A2447G (GenBank accession no. AF467082), which did not led to amino acid variation in the 3'-untranslated region. Association analysis of early egg production traits showed that egg number at 36 weeks of FSHBpro locus in blue eggshell chicken was significant difference between AA and AB (P＜0.05), simultaneity, in exon3 site, the age at first egg was also significant difference between AA and AB (P＜0.05);The egg number at 20 weeks after the age at 50% egg of genotype BB were six eggs higher than that of AA and AB.Considering, FSHB 5'regulation region should be marker-assisted selection(MAS).3 Polymorphisms in ESRa gene and association with egg production traitsThe SSCP detection of 5' flanking regulation region and intronl in ESRa gene showed that two genotypes were detected in 5'flanking regulation region of blue eggshell chicken.Four SNPs, A-34G, T-76C, T-79C, C-102T,were identified.The frequence ofallele C and D were 0.86,0.14, respectively. The SNPs did not led to amino acid variation in the 5'-untranslated region; No polymorphism was found in 5' flanking regulation region of ESRa gene in TaiHu population. In addition,three SNPs, T122C, A155G, C169T,were identified in ESRaintron 1 of blue eggshell chicken. To blue eggshell chicken,association analysis of early egg production traits showed that the egg number at 36 weeks was significant difference between genotype GC and CD (P＜0.05).4 Interaction analysis among PRL, PRLR, FSHB and ESRa genes To TaiHu chicken, significant interactions between PRLRexon3 and PRLRexon6 were detected in interaction analysis of PRL, PRLR and FSHβgenes (p＜0.01), and the incorporative genotype CCFF is available to breed TaiHu chicken variety.To six loci of four genes in bule eggshell chicken, significant interaction between FSHβpro and FSHβexon3 was detected(p＜0.01),but no significant difference between egg production traits at 36 weeks of incorporative genotypes(p＞0.05). Conjectureing some mutations are available to egg production traits, the others are disadvantageous to egg production traits. Therefore, all kinds of molecule biology techniques must are used to detect gene mutations of influencing egg production traits, provide integrated and veracious theory thereunder for breeding.
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