Generation of cloned transgenic pigs rich in omega-3 fatty acids

BRIEF COMMUNICATIONSGeneration of cloned transgenic

pigs rich in omega-3 fatty acids.com/naturebiotechnology Nature Publishing Group Liangxue Lai1,2,8, Jing X Kang5,8, Rongfeng Li1,

Jingdong Wang5, William T Witt6, Hwan Yul Yong1,

Yanhong Hao1, David M Wax1, Clifton N Murphy1,

August Rieke1, Melissa Samuel1, Michael L Linville3,

Scott W Korte4, Rhobert W Evans7,Thomas E Starzl6, Randall S Prather1,2 &Yifan Dai6Meat products are generally low in omega-3 (n-3) fatty acids,

which are beneficial to human health. We describe the

generation of cloned pigs that express a humanized

Caenorhabditis elegans gene, fat-1, encoding an n-3 fatty

acid desaturase. The hfat-1 transgenic pigs produce high levels

of n-3 fatty acids from n-6 analogs, and their tissues havea significantly reduced ratio of n-6/n-3 fatty acids (P o 0.001).The health benefits of long chain n-3 fatty acids, found mainly in fish

oils, are well recognized. Meat products normally contain small

amounts of n-3 fatty acids and large amounts of n-6 fatty acids1.

Diets with a high ratio of n-6/n-3 fatty acids may contribute to the

prevalence of many diseases, such as coronary artery disease, cancer,

diabetes, arthritis and depression2. The high n-6/n-3 ratio in meat

products is largely due to the extensive use of grains rich in n-6 fatty

acids but deficient in n-3 fatty acids as animalfeed. In addition, livestock cannot convertn-6 fatty acids into n-3 fatty acids becausethey lack an n-3 fatty acid desaturase gene,such as the fat-1 gene found in the roundworm C. elegans3. Earlier

work in transgenic mice carrying the fat-1 gene has suggested the

feasibility of creating fat-1 transgenic livestock capable of producing

n-3 fatty acids from the corresponding n-6 fatty acids4. Here we report

the cloning of fat-1 transgenic pigs that produce high levels of n-3 fatty

acids in their tissues and organs.An hfat-1 expression vector, pCAGGS-hfat-1, which contains a

humanized fat-1 cDNA (with modification of codon usage) driven

by the cytomegalovirus enhancer and chicken b-actin promoter,

has been described previously4. A pgk-neo expression cassette as a

selection marker was inserted into pCAGGS-hfat-1 to generate

pST103, which was transfected into early-passage male primary

porcine fetal fibroblast cells, pCFF4-35, by electroporation; the transfected cells were selected with 250 mg/ml G418. The G418-resistant

colonies were pooled. Gas chromatographic analysis showed that

pCFF4-3/pST103 cells contained higher amounts of n-3 fatty...