Changes in the muscle proteome after compensatory growth in pigs

Differences in pig muscle proteome according to HAL genotype: implications for meat quality defects

Bidimensional electrophoresis was used to compare sarcoplasmic protein profiles of early post-mortem pig semimembranosus muscles, sampled from pigs of different HAL genotypes (RYR1 mutation 1841T/C): 6 NN, 6 Nn, 6 nn. ANOVA showed that 55 (18%) of the total of 300 matched protein spots were influenced by genotype, and hierarchical clustering analysis identified 31 (10% of the matched proteins) additional proteins coregulated with these proteins. Fold-changes of differentially expressed proteins were between 1.3 and 21.8. Peptide mass fingerprinting identification of 78 of these 86 proteins indicates that faster pH decline of nn pigs was not explained by higher abundance of glycolytic enzymes. Results indicate further that nn muscles contained fewer proteins of the oxidative metabolic pathway, fewer antioxidants, and more protein fragments. Lower abundance of small heat shock proteins and myofibrillar proteins in nn muscles may at least partly be explained by the effect of pH on their extractability. Possible consequences of lower levels of antioxidants and repair capacities, increased protein fragmentation, and lower extractability of certain proteins in nn muscles on meat quality are discussed.

The effect of weight loss on protein profiles of gastrocnemius muscle in rabbits: a study using 1D electrophoresis and peptide mass fingerprinting

The study of physiological changes occurring during selection contributes to an improved understanding of relationships leading to efficiencies in animal production. To investigate the effects of food restriction in gastrocnemius muscle protein expression, 20% weight reduction was induced in New Zealand White (meat producing) and wild rabbits, using one-dimensional gel electrophoresis and peptide mass fingerprinting. Lower expression levels of myosin heavy chains were found in the Wild Rabbits Restricted Group, while myosin light chain and alpha-crystallin proteins were not detected in restricted groups. Glyceraldeyde-3-phosphate dehydrogenase and glycogen phosphorylase expression levels were similar for all experimental groups. Phosphopyruvate hydratase beta was not detected in the wild rabbit restricted diet group. Pyruvate kinase levels were 50% lower in the New Zealand Restricted group. LIM protein detection was absent in the control New Zealand group. Results also show relevance of actin in preserving muscle structure in depressed food availability, the sensitivity of both myosin light chain and alpha-crystallin protein to restricted feed and the role of PK in the resistance of New Zealand rabbits to food restriction.

Intrauterine growth restriction affects the proteomes of the small intestine, liver, and skeletal muscle in newborn pigs

Efficiency of nutrient utilization is high in neonates with normal birth weights but is reduced in those with intrauterine growth restriction (IUGR). However, the underlying mechanisms are largely unknown. This study was conducted with the piglet model and proteomics technology to test the hypothesis that IUGR affects expression of key proteins that regulate growth and development of the small intestine, liver, and muscle, the major organs involved in the digestion, absorption, and metabolism of dietary nutrients. Jejunum, liver, and gastrocnemius muscle were obtained from IUGR and normal birth-weight piglets at birth for analysis of proteomes using the 2-dimensional-PAGE MS technology. The results indicate that IUGR decreased the levels of proteins that regulate immune function (immunoglobulins and annexin A1), oxidative defense (peroxiredoxin 1, transferrin, and zeta-crystallin), intermediary metabolism (creatine kinase, alcohol dehydrogenase, L-lactate dehydrogenase, prostaglandin F synthase, apolipoprotein AI, catecho O-methyltransferase, and phosphoglycerate kinase 1), protein synthesis (eukaryotic translation initiation factor-3), and tissue growth (beta-actin, desmin, and keratin 10) in a tissue-specific manner. In addition, IUGR increased the levels of proteins that are involved in proteolysis (proteasome alpha-5 and alpha-1 subunits), response to oxidative stress (scavenger-receptor protein and alpha-1 acid glycoprotein), and ATP hydrolysis (F1-ATPase). These novel findings suggest that cellular signaling defects, redox imbalance, reduced protein synthesis, and enhanced proteolysis may be the major mechanisms responsible for abnormal absorption and metabolism of nutrients, as well as reduced growth and impaired development of the small intestine, liver, and muscle in IUGR neonates.

Proteome Changes in Bovine Longissimus Thoracis Muscle During the Early Postmortem Storage Period

Postmortem changes in protein composition up to 24 h in bovine longissimus thoracis muscle were investigated by two-dimensional gel electrophoresis and MALDI-TOF MS/MS. A total of 47 spots were significantly changed the first 24 h postmortem. The 39 identified proteins can be divided into five groups: metabolic enzymes, defense and stress proteins, structural proteins, proteolytic enzymes, and unclassified proteins. The identified metabolic enzymes are all associated with ATP-generating pathways, either the glycolytic pathway or energy metabolism. In addition, several defense and stress proteins were changed in abundance in this study. These findings contribute to a better understanding of the biochemical processes during postmortem storage of meat.

Does feed restriction and re-alimentation differently affect lipid content and metabolism according to muscle type in pigs (Sus scrofa)?

This study aimed to investigate whether feed restriction and re-alimentation differently affect lipid content and activities of lipogenic or catabolic enzymes according to muscle types in pigs. At around 28 kg body mass (BW), sixty pigs (n=30 per group) were allocated to either ad libitum (AL) or restricted/re-feeding (RA) regimens. After feed restriction (80 kg BW), lipid content was reduced (P<0.01) in the oxidative rhomboideus (RH) as in the glycolytic biceps femoris (BF) muscles of RA pigs compared with AL pigs. Lower activities (P<0.05) of the lipogenic enzymes fatty acid synthase (FAS) and malic enzyme (ME) were observed in the RH but not in the BF of RA vs. AL pigs. After re-feeding (110 kg BW), lipid content was restored in the RH, but was still 12% lower (P<0.05) in the BF of RA compared with AL pigs. In the RH, the trend for an enhanced FAS activity and for a smaller weight-related decrease of ME activity in RA pigs than AL pigs during re-feeding, may have contributed to the muscle fat recovery observed in the RA pigs. In the BF, higher oxidative enzyme activities (P<0.10) in RA pigs compared to AL pigs might explain the incomplete lipid recovery observed after re-feeding in the former animals. In conclusion, metabolic activities in response to restriction and re-feeding differed according to muscle metabolic type.