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Variations Of TPH Gene Family And Their Relationship With Seasonal Reproduction Of Sheep

Posted on:2021-03-14Degree:DoctorType:Dissertation
Country:ChinaCandidate:C H LiuFull Text:PDF
GTID:1363330611982880Subject:Animal breeding and genetics and breeding
Abstract/Summary:PDF Full Text Request
Seasonal reproduction severely limits the balanced production of sheep.It is essential to study the molecular mechanism of seasonal reproduction for breeding new sheep breeds which able to reproduce annually.Sheep respond to seasonal changes by changing the synthesis and secretion of melatonin(MLT)in the pineal gland and seasonal reproduction can be formed.In mammals,there are 13 genes involved in the MLT synthesis,degradation and ligand-binding process of melatonin.The purpose of this study is to explore the formation process and mechanism of sheep seasonal reproduction and screen the variation related to seasonal reproduction by using multi omics method to provide theoretical basis for breeding new breeds of sheep which able to reproduce annually.The positive selection signals of 13 melatonin related genes in mammals and Mongolian sheep populations were detected by using the reference sequence in Gen Bank and the whole genome sequencing data of Mongolian sheep,respectively.The eukaryotic expression vectors of wild type and mutant type were constructed according to the positively selected SNPs.The proteins were expressed in HEK293T cells and its enzyme activity was determined in vitro.The transcription levels of TPH1,transcription factors on TPH1 upstream and spermatogenesis related genes in hypothalamus,pituitary gland and gonad of male and female livestock were detected.The relationship between transcription levels of these genes was analyzed.The 1325th nucleotide in the coding sequence of TPH1 gene was significantly positively selected and functional associated,its allele T in 88.9%of seasonal reproducing mammals and C in 89.5%of annual reproducing mammals.This mutation might change the 442nd amino acid in the tetramer domain from Leu to Pro.One new nonsynonymous mutation was detected at the 865th nucleotide on TPH1 gene in six Mongolian sheep,which occurred between 5844 and 724 years ago.The mutation was only detected in Hu sheep.The frequency of allele T was 89.66%,and that of allele G was 10.34%.The mutation changed the 289th amino acid in the active center of TPH1from Phe to Val,which might affect the three-dimensional structure and hydrophobicity.The activity of the expression product of TPH1-Wild was 5 times higher than that of TPH1-T1325C,indicating that the mutation significantly reduced the activity of TPH1protein(p<0.01).Meanwhile,the activity of the expression product of TPH1-Wild was almost 2 times higher than that of TPH1-T865G,suggesting that the mutation significantly reduced the activity of TPH1 protein(p<0.05).Among the genes related to gametogenesis,there was a significant regression between the transcription of STRA8,DMC1 and STAG3 and TPH2 genes(p<0.05).Among the 35 specific transcription factors of TPH2 gene,the transcription of FOXD3 and TPH2 genes in testis and ovary had a significant regression relationship(p<0.05).As two main members of TPH gene family,the TPH1 and TPH2 genes have been significantly functional diverged in mammalian.In sheep,(1)TPH1 gene is important to regulate the seasonal reproduction.Two mutations(T865G and T1325C)were found in this gene,which affected the efficiency of transforming optical signal into MLT chemical signal by changing the activity of TPH1 protein,and result in change in the seasonal reproduction characteristics of sheep.(2)The results also suggested that TPH2 gene might be related to meiosis during spermatogenesis.In summary,TPH1 gene can be used as a candidate gene for breeding or gene editing to create new annual reproducing sheep.
Keywords/Search Tags:TPH gene family, sheep, melatonin, seasonal reproduction
PDF Full Text Request
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