Preliminary Assembly Of Mongolian Sheep Genome And Transcriptome Analyses Of Cold Tolence In Mongolian Sheep

Mongolian Sheep, being known to its hardiness and good meat quality, is the ancient sheep breed in China. The genome contains a great deal of precious genetic resources.In this study, we sequened the whole-genome of the Mongolian sheep using Illumina Hiseq2000sequencing technology platform and the whole-genome shotgun sequencing approach, in order to provide the base of filtering the genes with fine properties such as anti-coldness, disease resistance etc.. The result showed that the genome size was estimated in2.91Gb. Assembly contig N50length is20.1Kb, scaffold N50length is2731.3Kb. Average GC%of the sequence was42%, and the GC average depth is more than40×in coverage distribution. Repeat sequence is1.01Gb, accounting for34.71%, and transposable elements is accounting for90%in repeat sequence. Using the gene structure and gene function annotation,21,704genes were predicted, the function of20,600genes were noted, the size of the non-coding RNA accounts for0.015%of the genome. There are17,015gene families in Mongolian sheep.Based on the genome research, we used aCGH system to identify the CNVs in the sheep genome and constructed the CNVs map in Mongolian sheep, Kazakh sheep, Tibetan sheep, Hu sheep and Dorper sheep.51CNVRs were tested containing24gains,22losses and5gain-losses. The HBB gene was amplified in Mongolian sheep and Tibetan sheep, which may be attributed to adaptability in low oxygen and high altitude environment.For the cold-resistance of Mongolian sheep, Doper Sheep as reference, we sequenced the transcriptome of fat, muscles, adrenal glands and hypothalamus in the cold condition using Iliumina/Solexa technology, and selected529,75,268and161differently expressed genes. According to differently expressed genes of fat tissue by KEGG signaling pathway, the results were mainly related with fat cell differentiation, lipid synthesis, energy metabolism.133up-regulated genes were filtered in fat, in which RXR, FATP, AQP7involved in PPAR cell signaling with the function of accelerating preadipocyte differentiation and transporting long-chain fatty acid; GPAT3, ALDH involved in glycerolipid metabolism signaling pathway and regulate the synthesis of triglyceride; IRS1and LEP involved in the regulation of energy metabolism; the ribosome28S subunit and18S subunit involved in protein synthesis.10differently expressed genes which played an important role in lipid synthesis and energy metabolism were selected to be verified using q-PCR. The results were equivalent to RNA-seq. In cold conditions, the level of lipid synthesis and energy metabolism and protein synthesis in fat tissue of Mongolian sheep was higher than Doper Sheep, which showed Mongolian sheep resisted energy consumption by accelerating fat and increasing β-Oxidation; therefore, fat tissue was fundamental to the cold-tolerance of Mongolian sheep. The establishment of transcriptomes database of Mongolian sheep reveals hereditary basis of anti-coldness.