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Prion protein gene polymorphism in polish black-and-white cattle

Krysztof Walawski, Czarnik Urszula. 2002. Prion protein gene polymorphism in polish black-and-white cattle. In : Second international symposium on Candidate Genes for Animal Health (C.G.A.H), Montpellier, France, August 16-18th 2002 : abstracts. CIRAD, INRA. Montpellier : CIRAD, Résumé, 1 p. International Symposium on Candidate Genes for Animal Health. 2, Montpellier, France, 16 August 2002/18 August 2002.

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Additional Information : Session 4 : Genetic resistance / susceptibility to non-infectious diseases

Abstract : The conformation changes of prion protein (PRNP) is probable a pathogenic factor of BSE (Bovine Spongiform Encephalopathy). Deformed PRNP molecules are cumulated in the brain and spinal cord, forming the amyloid structure, resistant to the proteolytic enzyme activity. Expression of BSE has a source in the environmental influence. However, the conformation changes are possible as the result of gene mutation, involved in protein synthesis. Within PRNP gene, a deletion of the DNA fragment, located in the exon 3 ORF region was detected. Occurrence of 3 allelic variants. determined structure of 5, 6 or 7 octa- (or nine-) repeats of amino acids sequence is known in cattle. In all breeds, PRNP6 allele occurs most often, PRNP5 occurs immediately low, while PRNP7 was identified only in Swiss Brown cattle. The procedure of BSE diagnosis depends on the brain post-mortem. Therefore, application of molecular methods for detection of normal and changed PRNP gene fragment is a logically supported direction in further investigations. Presented research comprised characterisation of PRNP gene polymorphism in the Polish Black-and-White cattle. The investigation included representative groups of highly selected 150 AI sires and 190 sire-mothers as well as, mass population of 376 cows kept in commercial herds. PRNP gene polymorphism. was determined by means of the PCR procedure. Two variants of the PCR product size and three genotypes: PRNP 5/5 - distinguished by one shorter product, PRNP 5/6 - characterised by an occurrence of two varied size products and PRNP 6/6 - showing one longer PCR product were recorded. Recognition of PRNP heterozygous animals is unproblematic, while the identification of homozygous in some cases was difficult. To avoid incorrect reading, DNA samples of homozygous were combined with DNA of PRNP reference sample, and re-tested using PCR procedure. The correctness of genotype identification was confirmed by obtaining a one-band picture (in cases of PRNP 6/6) or two-band picture (in cases of PRNP 5/5). Polish Black-and-White cattle population is improved by using HF sires. The elite breeding groups of AI sires and sire-mothers are characterised a close genetic similarity to HF breed, while the mass population consist the animals with a significant level of autochthonous genes. These regularities are confirmed by the results of presented investigation. The allele frequencies calculated for whole examined population amount: PRNP6 - 0.891 and PRNP5 - 0.109. However, the cows from commercial herd are characterised by a significantly higher frequency of PRNP5 (q=0.134), in comparison to AI sires (q=0.077) and sire-mothers (q=0.084). Additionally, sire-mothers and mass population cows are distinguished by occurrence of PRNP 5/5 homozygous animals, which have not been found in AI sire group, and so far examined HF populations. The genetic equilibrium is generally preserved however, in the group of sire-mothers was observed the tendency of heterozygous decreasing as well as, PRNP 5/5 homozygous increasing (A2=7.81; 2 df). So far, in carried out investigations no differences in the PRNP gene frequencies in healthy and BSE animals have been observed. However, in BSE group, no cases of PRNP 5/5 genotype were recorded. The indication of these animals as BSE resistant can not be statistically verified for very low PRNP 5/5 frequency. On the other hand, unbalanced genetic structure induces a need for an explanation the dependence between PRNP gene polymorphism and the variability of biological features and important breeding traits. (Texte intégral)

Mots-clés Agrovoc : Prion, Polymorphisme génétique, Encéphalopathie spongiforme bovine

Mots-clés géographiques Agrovoc : Pologne

Classification Agris : L10 - Animal genetics and breeding

Auteurs et affiliations

  • Krysztof Walawski, University of Warmia and Mazury (POL)
  • Czarnik Urszula, University of Warmia and Mazury (POL)

Autres liens de la publication

Source : Cirad - Agritrop (https://agritrop.cirad.fr/512063/)

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