Distinctive Genes Determine Different Intramuscular Fat and Muscle Fiber Ratios of the longissimus dorsi Muscles in Jinhua and Landrace Pigs

Abstract

Meat quality is determined by properties such as carcass color, tenderness and drip loss. These properties are closely associated with meat composition, which includes the types of muscle fiber and content of intramuscular fat (IMF). Muscle fibers are the main contributors to meat mass, while IMF not only contributes to the sensory properties but also to the plethora of physical, chemical and technological properties of meat. However, little is known about the molecular mechanisms that determine meat composition in different pig breeds. In this report we show that Jinhua pigs, a Chinese breed, contains much higher levels of IMF than do Landrace pigs, a Danish breed. We analyzed global gene expression profiles in the longissimus dorsi muscles in Jinhua and Landrace breeds at the ages of 30, 90 and 150 days. Cross-comparison analysis revealed that genes that regulate fatty acid biosynthesis (e.g., fatty acid synthase and stearoyl-CoA desaturase) are expressed at higher levels in Jinhua pigs whereas those that regulate myogenesis (e.g., myogenic factor 6 and forkhead box O1) are expressed at higher levels in Landrace pigs. Among those genes which are highly expressed in Jinhua pigs at 90 days (d90), we identified a novel gene porcine FLJ36031 (pFLJ), which functions as a positive regulator of fat deposition in cultured intramuscular adipocytes. In summary, our data showed that the up-regulation of fatty acid biosynthesis regulatory genes such as pFLJ and myogenesis inhibitory genes such as myostatin in the longissimus dorsi muscles of Jinhua pigs could explain why this local breed produces meat with high levels of IMF.

The novel gene pFAM134B positively regulates fat deposition in the subcutaneous fat of Sus scrofa

“…BF702245.1 was much higher than Landrace in SAT at 90 d, which is coincident with the rules that IMF of LD and SAT is increased significantly at 90 d compared with Landrace pigs [14], we presumed that it might play some functional roles in fat deposition. Full-length cDNA sequence of the candidate gene was cloned by RACE technology according to the known EST sequence (BF702245.1), and then submitted to NCBI (GenBank Accession No.…”

“…The difference of the genotypes between the two breeds is the foundation for resulting in the difference of phenotypes of the difference of the SAT deposition. It was reported that the body fat ratio and back fat thickness of Jinhua pigs was significantly higher than that of the Landrace pigs at each developmental stage, especially 3.34 and 3.42-fold increase at 90 d, respectively [14].…”

“…The RNA extraction, microarray hybridization and microarray data analysis were carried out by using the published methods previously [14].…”

The effect of breed and feeding level on carcass composition, fatty acid profile and expression of genes encoding enzymes involved in fat metabolism in two muscles of pigs fed a diet enriched in n-3 fatty acids. A preliminary study

“…Opposite results were obtained by Gao et al (2011), who reported lower SCD expression in Northeastern Indigenous pigs having a higher IMF content, but the animals were slaughtered on day 150 regardless of their final BW. The results reported by Wu et al (2013) seem to indicate that SCD expression may be affected by the age of animals. The authors found that SCD expression in the LD muscle of Jinhua pigs that grow faster and have a higher IMF content was greater in 30-day-old pigs and smaller in animals aged 150 days.…”

Intermuscular and intramuscular adipose tissues: Bad vs. good adipose tissues

“…144,163 In pigs, positive association between the IM content and the expressions of myosin (MYL1), adipose-specific phospholipase A2 (AdPLA), melanocortin 4 receptor (MC4R), phosphoenolpyruvated carboxykinase (PEPCK), and SCD, and novel porcine FLJ36031 (pFLJ) genes are suggestive of their role in fast glycolysis and lipid deposition. 142,145 Genomewide-association studies (GWAS) and the liver RNA-Seq on female pigs with extreme phenotypes for IM showed differential expression of transposable elements, long non-coding RNAs. 151,164,165 Furthermore, these studies established the role of putative protein-coding genes including Endotoxin lipopolysaccharide/pro-inflammatory cytokines (LPS/IL-1) in mediating inhibition of retinoid X receptors (RXR) function to regulate cholesterol homeostasis and bile acid homeostasis ( Table 3).…”