Molecular cloning and functional analysis of MRLC2 differential expressed in MeishanxYorkshire F1 crossbreeds and their parents, Meishan pigs

Biological mechanisms of growth performance and meat quality in porcine muscle tissue

Growth performance and meat quality are important traits for pig production. The aim of the present study was to investigate the molecular mechanisms underlying growth performance and meat quality, and to identify novel target molecules for predicting the growth performance and meat quality. The differentially expressed genes (DEGs) in Diannan small ears pigs (DSP) and Landrace pigs (LP) were assessed by RNA-sequencing analyzing technology. A total of 339 DEGs were obtained between DSP and LP. 146 DEGs were upregulated in LP compared with DSP and 193 DEGs were upregulated in DSP compared with LP. The DEGs were significantly enriched in 26 GO and 3 KEGG pathways. The protein-protein interaction (PPI) network with 201 nodes and 382 edges was constructed and 5 modules were extracted from the entire network. The identified upregulated expression of genes involved in glycolysis and myogenesis as well as extracellular matrix may be associated with fast body and muscle deposition rates in LP. Increased expression of genes involved in PPAR signaling pathway and fatty acid metabolism as well as oxidative phosphate processes could be related to the intramuscular fat deposition and meat quality in DSP. The present study may provide an improved understanding of the growth performance and meat quality.

Molecular characterization, expression patterns, and polymorphism of a differentially expressed porcine gene (PYGM) isolated by suppression subtractive hybridization and two-dimensional gel electrophoresis analysis

Suppression subtractive hybridization was performed to detect the differences in gene expression of porcine longissimus dorsi muscles between Large White and Chinese Meishan pigs. An upregulated gene in Large White that shared high homology with human muscle glycogen phosphorylase (PYGM) was identified. The porcine PYGM gene contains an open reading frame encoding 842 amino acid residues with 26 and 283 nucleotides in the 5' and 3' untranslated regions, respectively. Tissue distribution analysis indicated that porcine PYGM mRNAs are highly expressed in all tissues. Expression pattern of PYGM was similar in the two breeds. Both breeds had the highest expression levels when 120 days old (p<0.01), and PYGM was upregulated during skeletal muscle development. A similar expression pattern of PYGM in protein level was also observed by differential proteome analysis of skeletal muscle development using two-dimensional gel electrophoresis and mass spectroscopy. The mRNA abundance of PYGM in Large White was higher than Meishan at all four stages (p<0.05). Moreover, a G/T mutation in exon 8 was identified and association analysis with meat quality traits showed that it was significantly associated with lean meat percentage (p<0.05). Our data may provide further insight into the molecular mechanisms responsible for breed-specific differences in porcine growth and meat quality.

Characterization of the porcine differentially expressed PDK4 gene and association with meat quality

To investigate the differential expression of genes in the skeletal muscle between Yorkshire and Chinese indigenous breed Meishan pigs, suppression subtractive hybridization was carried out and many genes were proved to be expressed significantly different in the two breeds. One gene highly expressed in Meishan but lowly expressed in Yorkshire specific library, shared strong homology with human pyruvate dehydrogenase kinase 4 (PDK4). Using semi-quantity and quantity PCR, We confirmed its differential expression between the two breeds. Temporal and spatial expression analysis indicated that porcine PDK4 gene is highly expressed in skeletal muscle and the highest in neonatal pigs. Complete cDNA cloning and sequence analysis revealed that porcine PDK4 gene contains an open reading frame of 1,221 bp. The deduced amino acid sequence showed conservation in evolution. A G/A mutation in intron 9 was identified and association analysis showed that it was significantly associated with intramuscular fat, muscle water content.