Effect of the RN(-) gene on ultrastructure and protein fractions in pig muscle

The aim of the present experiment was to study the effect of the RN^? gene on ultrastructure of white fibres and the proportion of the different protein fractions in Longissimus lumborum muscle of RN^? pigs. The ultrastructure of muscle was observed in 4 RN^? carrier pigs and 4 rn⁺rn⁺ homozygous pigs by mean of electron microscopy. Protein fractionation and quantification were performed on muscle from a second group of 4 RN^? and 4 rn⁺ pigs. No change in the proportions of the different protein compartments was observed. The abnormality of the glycolytic fibres of RN^? pigs seems to be rather due to an increase of the glucid concentration in the sarcoplasm, perhaps secondarily to a modified osmolarity in the intracellular medium.