A MicroRNA Omics Study On The Ovary Of Xiang Pig

Micro RNAs(miRNAs) are a class of endogenous non-coding RNAs with a length of about 22 nt.Mi RNAs play a role in post-transcriptional regulation by binding to the 3’UTR of target gene m RNA to degrade m RNA or inhibit the m RNA translation process.miRNAs are widely distributed in various eukaryotes,and they are involved in various life activities such as cell proliferation,differentiation,apoptosis,embryo development,substance metabolism,tumorigenesis and inhibition,and cell signal transduction.Xiang pig is a local pig breeds in Guizhou Province.It is an important economic animal with early sexual maturity and small litter size is the key factor hindering the development of Xiang pig production industry.This study aims to mine the micro RNAs regulating estrus from the small RNA sequencing data of the ovaries of Xiang pigs and analyze the molecular mechanism of estrus regulation in aromatic pigs to provide a theoretical basis for improving the litter size of aromatic pigs at the molecular level.In this study,the estrus and diestrus pigs were used as test animals.Total RNA was extracted from ovary tissues after slaughter for small RNA sequencing.Bioinformatics method was used to detect miRNA expression profile and screen differentially expressed miRNAs,and the target genes of differentially expressed miRNAs were predicted.Finally,miRNAs that regulate estrus in the ovary of Xiang pigs were preliminarily screened out.The main results of this study are as follows:1.Based on the high-throughput sequencing small RNA sequencing,using bioinformatics methods to detection Xiang pig ovary micro RNAs the results of that micro RNAs sequence in the diestrus more than the estrus,there’re a total of 68342 miRNA sequences in the diestrus ovary,it including 61448 micro RNAs of pig and6894 is homologous miRNA sequences.Total 71122 miRNA sequences in the estrus ovary,including 63530 is pig miRNA sequences and 7592 homologous sequences.2.The miRNA sequences of the ovary of pigs during estrus and diestrus showed the most homology with bovine miRNA sequences and the least homology with mouse miRNA sequences.Among the miRNA sequences of estrus and diestrus porcine ovaries,26.50% and 25.40% were conserved among pig,human,bovine and mouse.3.Sequence annotation of miRNA in the ovaries of Xiang pigs showed that miRNA molecules expressed in the ovaries of Xiang pigs during diestrus were more abundant than those in estrus.There were 607 and 594 miRNA molecules expressed in the ovaries of estrus and estrus,respectively.Among them,577 miRNA molecules co-expressed 17 and 30 miRNA molecules were specific to ovaries of estrus and estrus.4.According to the threshold of differential expression P <0.05 and log FC >;1 or log FC<;-1 was the screening condition.A total of 34 differentially expressed miRNAs were screened in this study,among which 21 were up-regulated and 13 were down-regulated.A total of 1189 unique target genes were obtained by the target gene prediction of differentially expressed miRNAs.5.Target genes were analyzed through GO enrichment and KEGG pathway,and it was found that the main biological processes involved included cellular process and metabolic process,which were mainly distributed in cells and cell parts.The Molecular functions mainly involve binding,catalytic activity,etc.The target gene pathways are concentrated in gonadotropin-releasing hormone receptor pathway,insulin-like growth factor pathway and epidermal growth factor signaling pathway(EGF)Signaling pathway).Many of the enrichment pathways are related to follicular development and granulosa cell apoptosis.Seven miRNAs(mi R-23 b,let-7i-5p,mi R-103,mi R-30e-5p,mi R-1271-5p,mi R-181 A,mi R-125b)that might regulate the estrus of Xiang-pigs were preliminarily screened out.6.The real-time fluorescence quantitative PCR test verified that the six miRNAs sequence(mi R-133b、mi R-143-3p、 mi R-7-5p、mi R-500-5p、mi R-145-5p、mi R-23b)were expressed in ovaries of Xiang pigs during estrus and diestrus.Compared with the results of sequencing analysis,the general trend was consistent.