Analysis The Myogenesis And Adipogensis-related Genes Expression In Fetal Skeletal Muscle Between Texel And Ujumqin Slieep During The Second Half Of Gestation

To select the most stable reference genes and investigate the developmental expression patterns ofmyostatin, MyoD, MyoG, Myf5, Pax7, PPARγ, leptin, C/EBPα, C/EBPβ and the important genes inmyostatin signal pathways such as AKT, P21, CDK2and p38MAPK genes in sheep fetal muscle.Quantitative RT-PCR was conducted for B2M, GAPDH， RPLPO, RPS18and SDHC and also appliedto investigate14genes mRNA expression of interest at the gestation of70d,85d,100d,120d and135d in longissimus dorsi muscle of Texel and Ujumuqin sheep. The main results were as follows:1. Selection of reference genesThe five reference genes expression stability was analyzed by the geNorm software, and the resultsshowed that RPS18>RPLPO>SDHC>B2M>YWHAB. Furthermore, SDHC, RPLPO and RPS18wereidentified as the most stable reference genes in the present study.2. Expression patterns of myostatin, MyoD, MyoG, Myf5and Pax7In all the five stages, the expression of myostatin in Texel was higher than that in Ujumuqin, andthe difference between the two breeds was significant (P<0.05). At the gestation of70d and85d, theMyoD, MyoG, Myf5and Pax7expression in Texel were higher than those in Ujumuqin, suggesting thatmyostatin could down-regulate the expression of Myf5, MyoD, MyoG and Pax7. Strikingly, theexpression patterns of MyoD were similar in the two sheep breeds, demonstrating that there might be acooperation effect between them.Four key genes Myf5, MyoD, MyoG and Pax7in the myogenesis regulation with the highexpression at the fetal of85d indicated that there was a unique proliferative surge in Texel sheep duringthe stage of85d.3. The expression patterns of AKT, P21, CDK2and p38MAPKIn all the five stages，the AKT, p38MAPK and CDK2genes expression in Texel were higher thanthose in Ujumuqin, but the P21was lower. In Texel, there were expression pecks of AKT and p38MAPKat the gestation of85d, but expression bottom of AKT. In addition, the difference of AKT was mostsignificant among the three genes between Texel and Ujumuqin sheep, demonstrating that myostatinmight regulate the muscle growth mainly through AKT gene.4. The developmental expression changes of PPARγ, leptin, C/EBPα and C/EBPβ in Texel andUjumuqin sheepThe expression of PPARγ and leptin were high at the gestation of70d，85d and100d, but that ofC/EBPα and C/EBPβ were at the gestation of100d，120d and135d during the two breeds. Theexpression of PPARγ, leptin, C/EBPα and C/EBPβ were all high at the gestation of100d, suggestingthat the fetal stage of100d might be the crucial period of intramuscular fat (IMF) development inUjumuqin sheep.In all the five stages, the PPARγ expression of Texel was higher than that in Ujumuqin, but theC/EBPα was lower, demonstrating that myostatin might negatively regulate the expression of C/EBPα and positively regulate the expression of PPARγ. In all the five stages, the differences of PPARγexpression between the two breeds were significant (P<0.01), but C/EBPα expression were notsignificant.