Biological response of rat fed diets with high tuber content of conventionally bred and transgenic potato resistant to necrotic strain of potato virus (PVYN). Part II. Caecal metabolism, serum enzymes and indices of non-specific defence of rats

The potential effect of genetic modification on nutritional properties of potatoes was determined in a rat experiment. The potato cultivar Irga was transformed with viral genome sequences in order to improve its resistance to a necrotic strain of potato virus Y (PVYN). Four clones of genetically-modified potato were compared with the conventional variety Irga and non-transgenic somaclone from cv. Irga. Autoclaved and dried potato tubers were introduced in a high amount (40%) to rat diets. The genetic status of the potato had no effect on the mass of the caecum and caecal digesta. The parameters tested were pH, dry matter content and bacterial enzyme activity, comprising α- and β-glucosidase, α- and β-galactosidase, and β-glucuronidase. The results indicate that improvement of potato resistance to PVYN by genetic transformation had no negative effect on the ecosystem of the caecum of the rats, activity of serum enzymes (aspartate and alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase and creatine kinase) and non-specific defence mechanisms (lysozyme and ceruloplasmine level, number of bacteria taken up per cell and the percentage of the phagocytic cells in the serum).