Study On Beef Intramuscular Fat Deposition Of SREBP1Gene In Cattle

The intramuscular fat is one of the important factors affecting beef quality, the amount anddistribution of fat within muscle are not only directly associated with quality and value of the meat, butalso the one of the more important factors that affect the health of consumers. In this study we usedpolymorphisms of the84bp indel in the intron5of bovine SREBP1（Sterol regulatory element bindingfactor1）gene of209Simmental bulls and128Dragon black cattle which was detected by PCR toevaluate their associations with beef fatty acid composition. We also constructed SREBP1eukaryoticexpression vector, and explored the function of SREBP1by cellular level overexpression tests. The mainresults were as follows：1. The frequency of the84bp indel in the intron5of bovine SREBP1gene was significantdifferences between tow breeds, the frequency of the deletion in Snow Dragon black cattle were0.211,and0.168in Simmental bulls, respectively.2. The84bp indel in intron5of SREBP1gene significantly associated with backfat thickness inSnow Dragon black cattle, backfat thickness was significantly higher in individuals with the SSgenotype as compared to LL and LS (P<0.05).3. The84bp indel in intron5of SREBP1gene significantly associated with palmitoleic acid(C16:1), stearic acid (C18:0), saturated fatty acids (SFA), triglycerides (TAG), and C16index inSimmental bulls (P<0.05), Cattle with LL genotype was higher amount of palmitc acid (C16:1),triglycerides and C16index than did those with the LS genotype, but lower stearic acid (C18:0) andSFA in LL compared to LS.4. SREBP1gene was cloned from muscle and then constructed SREBP1eukaryotic expressionvector. Recombinant plasmid was transfected into bovine fetal skeletal fibroblasts by Lipofectaminemediated method.5. Real-time PCR results showed that SREBP1gene and its downstream target regulatory geneSDC1expressed in both experimental group and control group, but its expression were significantdifferences. In experimental group both SREBP1and SCD1gene expression were significantly higherthan the control groups (P<0.05).6. Western-blotting results showed that fusion protein was successfully expressed in experimentalgroup. SREBP1protein expressead in both experimental group and control group, but in experimentalgroup SREBP1protein expression was significantly higher than the control groups.7. Oil Red O staining results showed that experimental group was stained with red, while in thecontrol groups, cells could not be stained. So the SREBP1gene has role to promote cell generates fat.