Candidate genes expression affect intramuscular fat content and fatty acid composition in Tan sheep
Ningxia Tan sheep meat is tender, has no strong smell, a delicious taste, and even fat distribution. Intramuscular fat (IMF) content and the composition of fatty acid (FA) both are important factors associated with meat quality, and are also important for meat tenderness and flavor assessment. We examined the correlation of candidate genes expression with these factors in four muscle tissues, including longissimus dorsi, triceps, biceps and supraspinatus from Tan sheep. The IMF and FA composition in the different muscle tissues were measured and associated with mRNA expression of related genes (PPARγ, C/EBPα, FAS, LPL, FABP4, and ACC). IMF content in longissimus dorsi muscle was 45.4% higher than that in triceps brachii (P < 0.05), 48.4% higher than that in biceps femoris, and 20.1% higher than that in supraspinatus. PPARγ, C/EBPα, FAS and LPL mRNA levels in supraspinatus were significantly different among longissimus dorsi muscle, biceps femoris and triceps brachii. There was significant positive correlation between IMF content and the relative mRNA expression of PPARγ, C/EBPα, FAS, LPL, FABP4 and ACC in longissimus dorsi muscle. The ratio of polyunsaturated fatty acids to saturated fatty acid was positively and significantly correlated with C/EBPα and ACC mRNA levels, and negatively and significantly correlated with FAS and FABP4 mRNA levels. Omega-6 fatty acid (ω6)/omega-3 fatty acid (ω3) ratio was positively and significantly correlated with C/EBPα, FAS and LPL mRNA levels, but negatively and significantly correlated with FAS and PPARγ mRNA levels. These correlations indicate that PPARγ, C/EBPα, FAS, LPL, FABP4, and ACC are key candidate genes for fatty deposits and the components and contents of FA in sheep, and the evaluation and functional verification of these genes may be useful for improving the meat quality of Tan sheep.