Cloning,Polymorphism Of GnRh And GnIH Genes And Their Association With Egg Production In Sichuan White Goose

The egg laying character is an important economic trait in goose,but the egg laying performance of goose is low,which seriously restricts the development of the goose industry.The reproductive ablities of birds are determined by the complex interaction of various hormones secreted by the hypothalamus-pituitary-gonadal axis system.GnRH and GnIH have been proved to be key signaling molecules in thissystem.The hypothalamus releases gonadontropin releasing hormone to the pituitary,influencing the release of gonadotropin hormone.Gonadotropin hormone works on gonad through peripheral blood circulation and controls the animals’ individual development and reproduction process by affecting the endocrine and exocrine of the gonad.At present,studies have shown that the GnRH and GnIH genes of pigs,cattle,sheep and other animals can be used as candidate genes that affected reproductive performance.There were few studies of GnRH and GnIH genes in geese.This research focused on the Sichuan White goose as the experimental animal.We cloned the DNA sequence,analyzed the sequence structure and screened the single nucleotide polymorphisms site in the genomic DNA sequence.PCR-RFLP and PCR-SSCP methods were used to detect the SNPs of GnRH and GnIH genes and to analyze the correlation between genotypes and egg productions.The following results are obtained:The length of GnRH genomic DNA was about 3520 bp,including four exons and three introns.The mRNA sequences comparison showed that the similarity of GnRH gene was highest with anser’s,reaching 92%.A total of 28 SNPs were detected in the goose GnRH gene,in which SNP(g.3447A>C)was detected in exon1,and the other 27 SNPs were detected in introns.The intron1(g.490A>G)mutation used PCR-RFLP by Bcl I.It was found that digestion produced 3 genotypes,which were defined as AA,AB,BB.There was no significant differences between the egg productions and these genotypes(P>0.05).The exon3(g.3447A>C)mutation produced 3 genotypes through PCR-SSCP.We did not find there was significant difference between egg productions and the three genotypes(P>0.05).The length of GnIH genomic DNA was about 7621 bp,including four exons and three introns.The mRNA sequence comparison showed that goose GnIH nucleotide sequence was similar to the grey goose,gallus,quail and other birds,the similar homologies were 99%,91%,90%.SNP scanning showed that there were 18 SNPs in introns and 15 SNPs in exons.There were three wrong mutations including: 230 bp at the deletion of GAA bases,2164 bp mutation at C>G,2228 bp mutation at the T>A,all led to amino acid changes,respectively,p.38 Glu InDel,p.100Pro>Arg,p.123Try>Asn.We found two genotypes through PCR-SSCP in 230 bp and 3262 bp,which were defined as AA,Aa and HH,Hh,There was no significant differences between the egg production and these genotypes(P>0.05).We used PCR-RFLP by Sma I and EcoR V in the intron1(g.1320G>A)and exon3(g.3553T>C).It was found that the egg productions of CC genotype was significantly higher than those of CD and DD genotypes(P<0.05).There was no significant difference between egg productions and three genotypes in 3553bp(P>0.05),which were named as EE,EF,FF.In summary,this research first obtained the DNA sequences and SNPs of the Sichuan white goose.The egg productions of CC genotype was significantly higher than those of CD and DD genotypes by the g.1320G>A mutation in GnIH gene.The results provided a basis for further study on the function of GnRH and GnIH gene in goose,and provided a reference for the study on the regulation mechanism of goose egg production.