Comparison Of Sheep Tail Morphology And Structure And Evolutional Relationship Of Tail Fat-Deposition Related Genes

The type of sheep tail is an important economic trait in sheep raising.In this paper,four types of sheep [(long fat-tailed Tan sheep(Tan),short fat-tailed Small-Tailed Han sheep(STH),and long-thin-tailed Gansu Alpine Fine-wool sheep(GAF)and short thin-tailed Tibetan sheep(Tib)] were investigated.From the perspective of the morphology of the tails and genes related to the regulation of tail fat deposition,we analyzed the differences in tail fat deposition and the regulation mechanism of fat tail sheep and lean tail sheep with the methods of molecular biology and morphology.Evolutionary and polymorphic methods were used for further understanding of the genetic differentiation between the fat-tailed and the lean-tailed sheep.The results showed that:(1)for tail phenotype,tail width and tail thickness were positively correlated with tail fat deposition;(2)the total number of the first-and the second-class tail vertebrae of long-tail sheep is generally 13,and that of third-and fourth-class tail vertebrae and the degree of degeneration vary greatly among individuals;Generally,there are 9 cases of the total number of first-and second-class tail vertebrae of short-tail sheep,and the individual differences of the total number of the third and fourth types of tail vertebrae and the degree of degeneration are small;(3)among different tail types,the width of the vertebral body with transverse process is positively correlated with the amount of tail fat deposition,and the largest width is in the long fat tail sheep(Tan)and the smallest in the short lean tail sheep(Tib);(4)compared with lean-tail sheep,fat-tail sheep increase tail fat deposition mainly by increasing the number of fat cells while inhibiting lipid degradation pathways;(5)PLIN1,a key gene for lipid metabolism,has a significant mutation in fat-soluble amino acids from Alanine to Valine in fat-tailed sheep,which may be related to differences in protein structure and function.The results indicate that fat deposition in fat-tailed sheep is mainly due to the increase in the number of fat cells and the inhibition of fat degradation,with the increase in the volume of fat cells,meanwhile,the mutation of the amino acid site in the PLIN1 protein in fat-tailed sheep may have an important relationship with fat-tailed traits.