Comparative Study On Small Non-coding RNA In Overwintering And Breeding Periods Of Onychostoma Macrolepis

Qinling Mountains are rich in economic animal germplasm resources.It is urgent to carry out the protection and artificial breeding of representative indigenous fish germplasm resources represented by Onychostoma macrolepis.O.macrolepis is expected to become the first export fish species in Shaanxi Province.In-depth research on the fish is conducive to strengthening the protection of this rare fish and maintaining the ecological balance of the Qinling Mountains.At the same time,it is beneficial to promote the industrialization development of O.macrolepis and the development of characteristic fish industry in Shaanxi Province.O.macrolepis is a fish endemic to China,belonging to Cyprinidae,Barbinae,and Onychostoma.It is a dominant species in Qinling-Bashan Mountains,Shaanxi Province,China.It has unique overwintering habits in cave springs and is an atypical cavefish.It inhabits caves from October to March and reproduces in June.But the regulation mechanism of overwintering and reproductive behavior is not clear.In this study,high-throughput sequencing and bioinformatic analysis were used to reveal the expression patterns of non-coding smallRNA(sncRNA)at different time(overwintering period and breeding period)and space(liver and ovary)in O.macrolepis.The roles of sncRNA in overwintering and reproductive processes were analyzed,which provided a novel perspective for uncovering characteristics of the unique overwintering ecology and reproductive physiology of an atypical cavefish.The main results are as follows:1.Among liver sncRNA,miRNA(62.42 %)was the most,followed by tsRNA(25.21 %)and piRNA(10.66 %),while the proportions of snRNA-derived RF,sdRNA and rsRNA were all less than 1 %.Among ovarian sncRNAs,miRNA(39.76 %)and piRNA(39.98 %)were the most abundant,followed by tsRNA(9.34 %)and rsRNA(9.83 %),and the abundance of other sncRNAs(2.09 %)was low.In addition,most of the nuclear tsRNAs in liver and ovary were originated from five tRNAs: tRNA-Gly-GCC,tRNA-Lys-CTT,tRNA-Glu-CTC,tRNA-Glu-TTC and tRNA-Asp-GTC.2.Although the difference of sncRNA expression among the early,middle and late overwintering period was little,there were significant differences between overwintering period and breeding period.Compared with the breeding period,the overall expression levels of liver rsRNA and miRNA and ovarian rsRNA were up-regulated in the overwintering period.Compared with the overwintering period,the overall expression levels of liver tsRNA and ovarian miRNA were up-regulated in the breeding period.3.In the liver,some up-regulated sncRNAs in the overwintering period,such as mi R-30-1 and tiRNA5-Asp-GTC-1,might affect the activities of ATPase,GTPase and pyruvate kinase,and regulate the functions of mitochondria and ribosome to reduce cell energy consumption;some up-regulated sncRNAs in the breeding period,such as let-7-1 and tiRNA5-Lys-CTT-1,might promote liver cell proliferation and tissue development,as well as sugar,lipid and protein synthesis and metabolism.In the ovary,some up-regulated sncRNAs in the overwintering period,such as mi R-125-1 and t RFi-Lys-CTT-1,might inhibit biomolecular metabolism and enhance stress tolerance;some up-regulated sncRNAs in the breeding period,such as mi R-146-1 and t RFi-Gly-GCC-1,might promote oocyte proliferation and maturation and ovarian development.In summary,sncRNA is an important regulatory factor in the overwintering and reproduction process of O.macrolepis.Different sncRNA types may have similar functions to coordinately regulate the development of liver and ovary and other physiological processes.The results of this study are of great significance to the protection of germplasm resources and artificial breeding.