Abstract：n-3 polyunsaturated fatty acids exerts multiple physiology functions, which has to be provided from foods in mammals. The fatty acid desaturase-1 gene (fat-1) encoding an n-3 fatty-acid desaturase converts n-6 to n-3 fatty acids, which plays an important role in improving meat quality. To understand the fatty acid composition of fat-1 transgenic sheep (Ovis aries). In the present study, sheep fetal fibroblasts were isolated and transfected with fat-1 overexpression plasmid. It was carried out that nuclear transfer and embryo implantation using the positive monoclonal and untransfected cells. Transgenic fat-1 sheep were obtained successfully. 32 fatty acids in 5 tissues were investigated by gas chromatograph attached to mass spectrometer for fatty acid determinator (GC-MS-QP2010). Reconstructed embryos (411 for untransfected fibroblast and 441 for fat-1 transgenic cell) at the 1-2 cell stage were transferred to the oviducts of 99 synchronism recipient sheep (47 for control and 52 for positive cell). 8 individuals were got, including 5 positive fat-1 transgenic and 3 control animals. 32 fatty acids were divided 3 categories: saturated (C12:0, C13:0, C14:0, C15:0, C16:0, C17:0, C18:0, C20:0, C21:0, C22:0, C23:0, C24:0), monounsaturated (C14:1, C15:1, C16:1, C17:1, C18:1n-9t, C18:1n-9c, C20:1n-9, C22:1n-9, C24:1n-9), polyunsaturated fatty acids (C18:2n-6t, C18:2n-6c, C18:3n-6, C18:3n-3, C20:2, C20:3n-6, C20:4n-6, C20:3n-3, C20:5n-3, C22:2n-6, C22:6n-3). The percentages of saturated, monounsaturated and polyunsaturated fatty acids were not significantly different between transgenic and control groups in brain and gluteus tissues. However, in transgenic sheep, saturated fatty acid decreased in liver, heart and testis tissues, monounsaturated fatty acids rose in liver and testis tissues, and monounsaturated fatty acids reduced in heart, polyunsaturated fatty acids decreased in liver tissue, but increased in heart and testis tissues. The content changes of monounsaturated fatty acid C18:1n-9c and saturated fatty acid C16:0, C18:0 determined the change trends on monounsaturated and saturated fatty acids in transgenic sheep. These 3 fatty acids were not significantly different between transgenic and control animals in brain and gluteus tissues. Furthermore, there were not significant difference in total polyunsaturated fatty acids in brain and gluteus tissues between transgenic and control groups. Looking into the 11 polyunsaturated fatty acids in brain and gluteus tissues, the results indicated that the percentage content of C20:2, C20:3n-3 and C20:4n-6 decreased, but C20:5n-3 and C22:6n-3 increased in fat-1 transgenic group. fat-1 decreased polyunsaturated fatty acids in liver tissue, and increased them in heart and testis tissues, which was mainly determined by C20:2 (eicosadienoic acid, EDA), C20:3n-3 (eicosatrienoic acid, ESA), C20:4n-6 (arachidonic acid, ARA), C20:5n-3 (eicosapentaenoic acid, ETE) and C22:6n-3 (docosahexaenoic acid, DHA) fatty acids. Both EPA and DHA increased in 5 tissues in transgenic sheep, especially EPA. The contents of C20:3n-3 and C20:4n-6 were decreased, and the contents of C20:5n-3 and C22:6n-3 are increased by fat-1, thus the ratio of n-3/n-6 fatty acids was increased. The present study clarifies the compositions and characterizations of fatty acids in fat-1 transgenic sheep, which provides theoretical evidence for exploiting high-quality sheep, improving the structure of fatty acid in human diet and reducing the risk of obesity.
