Gene Expression Profiling of Destructured Pig Semimembranosus Muscle

The destructured meat syndrome is clearly detrimental to cooked ham industry but still poorly understood. The affected muscles lose their fibrous aspect and give a soft whitened muscular mass without any organised structure. Normal (n=7) and destructured (n=7) groups of pigs were allotted 36 h post-mortem based on meat L* values. Transcriptome analysis of Semimembranosus muscles was conducted to identify genes potentially involved in this syndrome. Fifty nine genes were differentially expressed (p < 0.01) and 90% of them were upregulated in the affected muscles. Myofibrillar proteins involved in the contractile properties (TNNC2 and TNNT3) or in the integrity (TMOD4) of the sarcomere were increased in the affected muscle. Moreover, eight genes encoding enzymes of glycolysis (ALDOA, ENO3, GAPDH, LDHA, PGAM2, PKM2) or glycogenolysis (PGM1, PYGM) were upregulated in the destructured muscles. These results suggest that both myofibrillar and sarcoplasmic proteins might be involved in the etiology of this syndrom. Keywords: meat quality comparison Fourteen pigs were included in this study and alloted into two groups according to meat quality measurment. Pigs with low L* value were considered as normal and unaffected pigs (n=7) whereas pigs with high L* value were considered as affected pigs leading to destructured meat. Total RNA was isolated from each of the 14 semimembranosus muscle samples and controlled for quality and concentration using an AGILENT 2100 bioanalyzer. cDNA was synthesized and labelled from 5 µg total RNA by simultaneous reverse transcription of mRNA using SuperScriptTM II RNase H- Reverse Transcriptase and 33P-deoxy-CTP. Each muscle sample mRNA was hybridized at 68°C during 48 h to one array containing two duplicated parts (sample names ending by 1 correspond to the left part whereas sample names ending by 2 correspond to the right part). The arrays were then exposed to radioisotopic-sensitive imaging plates that were scanned thereafter with a phosphor imaging system at a 25 µm resolution. Hybridization images were quantified using a semi-automated software through a grid process with a fixed spot diameter (BZscan). The output was then subjected to the data analysis process.