The RYR1 gene encoding the Ca2+ channel of sarcoplasmic reticulum of human skeletal muscle has been cloned and its nucleotide sequence has been determined earlier. We have used the polymerase chain reaction single strand conformation polymorphism (PCR-SSCP), and sequencing analysis for human, porcine (Sus scrofa), and zebrine (Equus grevyi) ryanodine receptor (ryr1) gene. The fragment of exon 17 of the ryr1 gene was characterized by a high homology between all the analysed species (substitution of a nucleotide is underlined): porcine ryr1 1834GTG GCC GTG CGC TCC AAC CAA GAT CT1859 human RYR1 1831GTG GCC GTG CGC TCC AAC CAA GAT CT1856 zebrine ryr1 GTG GCC GTG CGC TCC AAC CAA GAC CT.
Malignant hyperthermia (MH) is a clinical syndrome in which genetically susceptible individuals respond to the administration of potent inhalation anaesthetics and depolarization skeletal muscle relaxants with skeletal rigidity, unstable blood pressure, tachycardia, arrhythmias, hyperventilation, hypoxia, lactic and respiratory acidosis and high fever. In studies of the genetic basis of MH, a mutation was identified in the porcine (C1843T) and human (C1840T) skeletal muscle ryanodine receptor (RYR1) gene. This gene is mapped on human chromosome 19q13.1. The RYR1 gene contains 106 exons, of which two are alternatively spliced.
To predict meat quality after slaughter, biopsy samples were taken from musculus longissimus lumborum et thoracis of live pigs at approximately 40 kg and 80 kg of weight. The obtained values from biopsies for pH1 and EC50 (electric conductivity) were compared with measurements after slaughter at a weight of approximately 110 kg. RYR1 genotypes were determined from blood samples using PCR-RFLP. Mating of Nn sows with two nn boars resulted in 72 Nn and 40 nn offspring. Significant differences between the two genotypes were found for pH1 and EC50 values for the three weights. The coefficients of correlation for the Nn genotype of the RYR1 gene between the values after slaughter and both the first and the second biopsy for pH1 and EC50 were very low (r = 0.06, r = 0.14, and r = 0.26, r = 0.26, P 0.05). For the nn genotype were r = ?0.23, r = ?0.15, and r = ?0.25, r = ?0.11 respectively. The values of pH1 and EC50 were highly correlated (r = ?0.52 to ?0.84, P 0.001) both within biopsies and after slaughter.
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