NGUYEN THI KIM KHANG1, DANYEL JENNEN1, LOTHAR MENNICKEN1, DAWIT TESFAYE1, SIRILUCK PONSUKSILI2, KARL SCHELLANDER1, KLAUS WIMMERS5, MICHAEL HOELKER1
1University of Bonn, Institute of Animal Science, Animal Breeding and Husbandry Group, Germany
2Research Institute for the Biology of Farm Animals (FBN), Germany
Egg yolk fatty acids are a functionally important source for the 22#226 and 22#223 polyunsaturated fatty acids. Decreasing the 22#226:22#223-PUFA ratio to 5:1 in human diets is considered to improve human health with respect to the risk of cancer, adiposity, diabetes and cardiovascular diseases. Genetic polymorphism of the Vietnamese local chicken breeds and European breeds are still poorly studied as DNA markers which could be used to reduce the 22#226:22#223-PUFA ratio. Members of the FADS family are considered the most crucial enzymes involved in the biosynthesis of the fatty acids. They introduce double bonds[n1] between defined carbons resulting in the desired fatty acid modifications and thereby, they change the fatty acid profiles on chicken. The objectives of this study were to identify, clone and show the expression of the functional candidate genes FADS1 and FADS2 and to compare potential polymorphisms for distinguishing breeds of different origins. Therefore, unrelated laying hens of Vietnamese local chicken breeds Ri, H'mong, Te, Noi and Ac as well as an European breed were used for this study. Liver tissue was collected to identify the candidate genes. The chicken cDNA sequence of FADS1 and FADS2 was obtained and SNPs located within both genes. In addition, real time PCR was performed to quantify the expression of the FADS1 and FADS2 genes in the different breeds. The results show that no polymorphisms were found in FADS2, while two were found in the FADS1 at position 391 (C->A) and 468 (C->T). The later showing an amino acid change from Val to Ala.The Ri and Ac chickens are dominant heterozygous (CA and CT, respectively), whereas Te, H'mong and Noi chickens are homozygous (CC) for both SNPs. The expression of FADS2 is stronger than FADS1 and the highest levels for both genes are observed in Te chicken. (This project was supported by the Federal Ministry of Education and Research, BMBF grant VNB02/B07, Germany).
Keywords: 22#223, 22#226, chicken, FADS1, FADS2, polymorphisms