Multi-omic Study On MRNAs And LncRNAs Of Sow Gonadal Axis During Puberty

Puberty is the begining with sow’s reproductive performance with firstly ovulating.Long non-coding RNA(lncRNA)is a mode of epigenetic regulation,involved in animal developing.It’s reported that lncRNA may affect animal puberty onset by regulating target genes.This study firstly collected 6810 records of puberty age in Duroc,Landrace and Yorkshire sow populations,estimated heritability of puberty age,and explored the effect of puberty age on sow lifetime reproductive performance combined with reproductive data;then,based on the full-sibling experimental design,pre-pubertal(n = 3)and in-pubertal(n = 3)sow gonad axis tissue(hypothalamus-pituitary-follicle)were our research subjects,using strand-specific RNA-seq and genome-wide DNA methylation sequencing technology,a new process was conducted to detect lncRNAs;based on this process,sequencing data of the transcriptome and DNA methylation were integrated and analyzed,and candidate mRNAs and lncRNAs affecting the initiation of sow puberty were screened,and their functional analysis was performed.The main results of present study were drawed as follows:(1)The heritability of age at puberty in sow is 0.25～0.42.Age at puberty significantly affected age at breeding(P > 0.05),and age at farrowing(P > 0.05).Age at puberty significantly affected sow culling parity,and sows with early puberty had higher parity.Age of puberty did not significantly affect the number of sow lifetime born alive piglets(P > 0.05),and lifetime birth weight(P > 0.05).(2)Compared with follicle,expression file of mRNAs in hypothalamus and pituitary were similar.1131,881 and 1492 differentially expressed genes were screened out in the hypothalamus,pituitary and follicles,respectively.These mRNAs were mainly enrich for estrogen signaling pathway,steroid hormone-mediated signaling pathway,signal transduction,GABAergic synapse,synapse,insulin secretion and oxytocin signaling pathway.In addition,157 differentially methylated genes,and 30 genes were overlapped with differentially expressed mRNAs in follicles.(3)A predicting pipeline for new lncRNAs was developed.A total of 28,919 new lncRNAs were detected,among which the largest number were long intergeneic non-coding RNAs(linc RNAs).Compared with mRNAs,lncRNAs have lower expression,shorter length and fewer exons.1020,733 and 1179 differentially expressed lncRNA transcripts were detected in the hypothalamus,pituitary and follicles,respectively.Target genes of differential lncRNAs are mainly enriched in oxytocin signaling pathway,estrogen signaling pathway,GABAergic synapse,synapse,insulin secretion and signal transduction.Many of these lncRNAs targeted IGF1,IGF1 R,FSHR,ESR1,ESR2 and KISS1,which were confirmed to regulate mammalian puberty onset.The main conclusions of this study are as follows:(1)age of the puberty is a medium heritability trait;(2)age at puberty affects the life productivity of the sow;(3)a predicting process of new lncRNAs was developed;(4)Compared with follicle,expression profiles of mRNAs and lncRNAs in the hypothalamus and pituitary were more similar;(5)expression profile of follicles lncRNAs in the in-pubertal was different from that in the pre-pubertal stage;(6)importantly candidate mRNAs and lncRNAs,affecting puberty onset,were screened.These research work laid a theoretical foundation for further exploration of the initiation mechanism of sow puberty.