Glycogen hyperaccumulation in white muscle fibres of RN- carrier pigs. A biochemical and ultrastructural study.
1. The dominant RN- gene affects meat quality of pigs by increasing the glycogen content of muscle. Glycogen localization was studied in Longissimus dorsi muscle from RN- carrier pigs (RN- pigs) and rn+ rn+ homozygous pigs (rn+ pigs). 2. Ultrastructural study showed an excess of glycogen in the sarcoplasm of white fibres from RN- pigs as compared to rn+ pigs. 3. Lysosome-enriched fractions extracted from muscles contained 6% of the tissue glycogen content in both types of pigs. The distribution of the glycogen particles between sarcoplasm and lysosomes appeared to be similar in both RN- and rn+ pig tissues. 4. White fibres from RN- pigs with an increased glycogen level showed two ultrastructural alterations: the sarcoplasmic compartment was abnormally enlarged and a large proportion of mitochondria was morphologically modified. 5. The RN- gene seems, therefore, to be associated with alterations in the glycolytic metabolism, in the distribution of proteic compartments and in the oxidative metabolism of white muscle fibres.
Estrade
M
M
Station de Recherches sur la Viande, INRA, CEYRAT, France.
Vignon
X
X
Rock
E
E
Monin
G
G
D000118:Acetylglucosaminidase / Q000378:metabolism; D000818:Animals; D006580:Genetic Carrier Screening; D006003:Glycogen / Q000378:metabolism*; D008247:Lysosomes / Q000378:metabolism; D008854:Microscopy, Electron; D008931:Mitochondria, Muscle / Q000378:metabolism / Q000648:ultrastructure; D009132:Muscles / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D013552:Swine
D006003:Glycogen; D000118:Acetylglucosaminidase