Abstract
This study was undertaken in order to examine whether any connection existed between the amounts of iron in forage and the sporadic occurrence of scrapie observed in certain parts of Iceland. As iron and manganese are considered antagonistic in plants, calculation of the Fe/Mn ratios was also included by using results from Mn determination earlier performed in the same samples. Forage samples (n = 170) from the summer harvests of 2001–2003, were collected from 47 farms for iron and manganese analysis. The farms were divided into four categories: 1. Scrapie-free farms in scrapie-free areas (n = 9); 2. Scrapie-free farms in scrapie-afflicted areas (n = 17); 3. Scrapie-prone farms (earlier scrapie-afflicted, restocked farms) (n = 12); 4. Scrapie-afflicted farms (n = 9). Farms in categories 1 and 2 are collectively referred to as scrapie-free farms. The mean iron concentration in forage samples from scrapie-afflicted farms was significantly higher than in forage samples from farms in the other scrapie categories (P = 0.001). The mean Fe/Mn ratio in forage from scrapie-afflicted farms was significantly higher than in forage from scrapie-free and scrapie-prone farms (P < 0.001). The results indicated relative dominance of iron over manganese in forage from scrapie-afflicted farms as compared to farms in the other categories. Thus thorough knowledge of iron, along with manganese, in soil and vegetation on sheep farms could be a pivot in studies on sporadic scrapie.
Highlights
The prion protein (PrP) occurs naturally in most organs
The iron concentration in the forage samples ranged from 57 mg kg-1 to 1379 mg kg-1
In 14 of the samples the iron concentration was less than 100 mg kg-1 and in three of the samples it was above 1000 mg kg1
Summary
The prion protein (PrP) occurs naturally in most organs. It is believed to have a role in copper metabolism and possibly in oxidative defense and functions of the central nervous system. The protein is present in both a free and a glycosylated form, bound to cell membranes. In prion diseases ( called transmissible spongiform encephalopathies (TSEs)), the prion protein takes on a pathological, misfolded form (often called PrPsc), leading to depositions of extracellular aggregates and spongiform degeneration (vacuolation) in the brain. A distinguishing feature of TSEs is their transmissibility between individuals of the same species, or even between individuals of different species [1,2,3,4]
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