| Prion diseases consists of a group of genetic, infectious, or sporadic fatal neurodegenerative diseases, of which Bovine spongiform encephalopathy (BSE), sheep scrapie, and human Creutzfeldt-Jakob disease (CJD) are the most notable ones, all of which invariably involve a post-translational modification process of the cellular PrP (PrPC) encoded by the host euchromosome PrP gene during the period it converted into the pathogenic PrP (PrPSc). Although there are some insights in the infectious and inheritable character of the prion diseases, it has been unclear what is really the physiological function of normal cellular PrP, species barriers for transmission of the diseases and the mechanism of prion propagation and its conformational change yet, and these questions highly restricted to further interpret the pathogenesis of prion diseases and the pathogenic mechanism of prion. The main aims of the current study was to provide the experimental materials and the theoretical evidences to further study the genetical rule of variability and polymorphism, the relationship between amino acid variation and its protein conformational change of artiodactyl PrP gene, as well as the genetic basis of the species barrier, and to set up the experimental technology flats. The following investigations were carried and the results are discussed.The total DNAs were extracted from peripheral blood of nine cattle (three yaks, three Holstein/Friesian and three Qinchuan cattle), three Tibetan sheep and three goats, four bactrian camels and one musk deer respectively. The PrP genes were amplified by polymerase chain reaction using two pairs of special primers, then cloned into pMD 18-T Vector. The sequencing analysis showed that the sizes of genes were 795 bp in the cattle, 771 bp in the sheep, goat and musk deer, 768 bp, 792 bp and 795 bp in the bactrian camels respectively. The coding sequences of the genes had the complete ORFs contained within a single exon and were basically same as those of the published PrP genes of the same animal species, genus or family. The cloned PrP genes in this experiment contained five or six copies of a short G-C-rich element, which encoded the octapeptide Pro-His-Gly-Gly-Gly-Trp-Gly-Gln or nonapeptide Pro-Gln/His-Gly-Gly-Gly-Gly-Trp-Gly-Gln. There were six repeating elements in the cattle genes (four octorepeats and two nonarepeats), five repeating elements in the sheep, goat and musk deer (three octorepeats and two nonarepeats), meanwhile, of the four camels studied, two of them had six repeating elements (four octorepeats and two nonarepeats) and the other two had five repeating elements (four octorepeats and one nonarepeat). All the amino acid sequence of these genes included a N-terminal signal peptide with 24 amino acids and a C-terminal signal peptide with 23 amino acids (except three camel genes which had a C-terminal signal peptide with 22 amino acids). The PrP gene sequences of yak, bactrian camel and musk deer had not been reported previously.Comparison analysis of these PrP genes revealed the identities and variations of the nucleotide sequence and its putative amino acid sequence. It was indicated that the homology within cattle ranged from 99.0 to...
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