Antioxidants in blood from sheep lines divergently selected for facial eczema resistance

Abstract

Romney sheep have been evaluated for resistance to facial eczema (FE) using a process which involves challenge with the FE toxin, sporidesmin, and they have been bred in selection lines for increased resistance (R) or susceptibility (S) to FE. There is evidence that sporidesmin exerts its toxic effects by generating reactive oxygen species, and protection can be afforded by a number of antioxidants and antioxidant enzymes. Our objective was to summarise three separate experiments to determine whether the R and S lines differed in antioxidant mechanisms, in search of a non-invasive genetic marker. Lines were compared for the activities of four enzymes in blood in Experiment 1, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), and glutathione reductase (GR), and for the concentration of the tri-peptide thiol, glutathione (GSH). SOD, CAT, and GSH were also recorded in Experiment 2, and GPX alone in Experiment 3. Heritabilities were estimated for SOD, A03050 Online publication date 27 May 2004 Received 11 September 2003; accepted 18 February 2004CAT, and GSH. SOD activity was lower and CAT activity was higher in the R than in the S line (P < 0.01 for both enzymes). GPX activity was higher in the R than in the S line in Experiment 1 (P = 0.002) and Experiment 3 (P = 0.06), whilst neither GR activity nor GSH concentration differed significantly between lines. Heritability estimates for SOD, CAT, and GSH were 0.19 ± 0.11, 0.63 ± 0.14, and 0.34 ± 0.14, respectively. It is concluded that selection for divergence in sensitivity to sporidesmin in sheep may have been successful partly because of correlated responses in activities of three antioxidant enzymes (SOD, CAT, and GPX), capable of scavenging reactive oxygen species. However, the divergence between resistant and susceptible sheep in blood antioxidant activity was not large enough to be a reliable indicator of individual FE resistance.

Identifying chromosomal selection‐sweep regions in facial eczema selection‐line animals using an ovine 50K‐SNP array

“…In our comparative studies of antioxidant enzymes in blood of FE‐resistant vs. FE‐susceptible selection lines, we detected significantly higher catalase and glutathione peroxidase activities in the former animals (Hohenboken et al . ). In contrast, we observed significantly higher superoxide dismutase activity in blood of susceptible rather than resistant animals; this enzyme was presumably superoxide dismutase 3, extracellular (encoded by SOD3 ).…”

“…The animals also were used to explore the mechanism of resistance by comparing the serum levels of antioxidant enzymes between the lines (Hohenboken et al . ). In genetic studies, these selection lines were used in three different types of experiments aimed to detect causative FE genes and loci.…”

Effects of quantitative trait loci and themyostatinlocus on trace and macro elements (minerals) in bovine liver, muscle and kidney

“…Hohenboken et al . () reported in sheep that the activity of SOD1 was lower in facial eczema‐resistant selection‐line animals than in susceptible‐line animals. SOD1 is located on BTA1 where no QTL were found.…”

A history of facial eczema (pithomycotoxicosis) research

“…Munday et al (1983) demonstrated that liver injury by sporidesmin in sheep could be reduced by giving exogenous antioxidants. Hohenboken et al (2004) examined the possibility that heritable facial eczema resistance might be the consequence of levels of blood antioxidants and antioxidant enzymes which differed significantly between selection lines of sheep. The authors concluded that "divergences between resistant and susceptible sheep were not large enough to be a reliable indicator of individual FE resistance.…”