Single-cell Transcriptome Sequencing Analyses The Gene Expression Differences In 16-day Embryos Of HulunBuir Short-tailed Sheep And Ujumqin Sheep

Hulunbuir short-tailed sheep is a nationally certified mutton sheep breed native to Inner Mongolia of China,and has been vigorously bred and developed by the Ministry of Agriculture.The breed is preferred by herdsmen due to its short tail phenotype,great meat yield,and high lean meant percentage,etc.,which indicate excellent economic and breeding value.The existing research focuses primarily on the genetic mechanism of its tail traits.The present study is the first attempt to reveal the mechanism of short tail formation by examining the early embryonic development.Methodologically,single-cell RNA-seq was used to identify the variations in different cell groups,pathway changes,and cell interaction at the cellular level.By the method,the potential molecular mechanism underlying the short tail phenotype was investigated at multiple levels and from different perspectives.The study identify the differences of gene expression in 16 day embryos of Hulunbuir short tailed sheep and Ujumqin sheep by the single-cell RNA sequencing.The results of the study are as follows:1.Analyze the differences of gene expression between the two types of embryos in early development,and some regulatory factors involved in tail development were excavated.It was found that Hulunbuir short tail sheep embryos were mainly composed of 8 cell groups and the Ujumqin sheep embryos were mainly composed of13 cell groups.2.Screening of highly expressed marker genes showed that Hippo pathway was enriched in notochord cell subsets and paraxial mesoderm cell subsets of Wujumqin sheep,suggesting that Hippo pathway was involved in the development and regulation of sheep tail.3.Gene expression analysis of four cell subsets of sheep embryonic: spinal cord cells,notochord cells,somite cells and paraxial mesoderm cells showed that Alpha-HS-glycoprotein(AHSG)and Alpha Fetoprotein(AFP)were highly expressed in the spinal cord cells of Ujumqin sheep;Insulin-Like Growth Factor Binding Protein 5(IGFBP5)and Follicular Statin(FST)were highly expressed in notochord cells of Ujumqin sheep;Vimentin(VIM)and Galectin-3(LGALS3)were highly expressed in somite cells.4.Via RNA rate analyses,the study found that the mesenchymal cells group in the early embryos of Ujumqin sheep tended to transform into notochord cells.The cell transformation may have regulated the tail development.Via cell interaction analyses,Insulin-Like Growth Factor 2(IGF2)was found to be an important regulator of the tail development.In conclusion,it was discovered that the 16-day embryo of Hulunbuir short-tailed sheep was composed of eight types of cells,and that of Ujumqin sheep was composed of13 types of cells;it was screened that Hippo,TGF,WNT and other signal pathways were jointly regulate tail development of sheep.