Glutathione concentrations in the red cells of Merino sheep

Abstract

Tasmanian Merino sheep show a bimodal distribution in the concentration of reduced glutathione (GSH) in their red cells, 40% of sheep having GSH values of around 27 mg GSH/100 ml red cells and 60% with values of about 92 mg GSH/100 ml red cells (Tucker & Kilgour, 1972). The GSH deficiency was shown to be due to an impaired activity of γ-glutamyl cysteine synthetase (γ-GC-S), the enzyme catalysing the first step of GSH biosynthesis (Tucker, Kilgour & Young, 1976). Family data indicated that the deficiency in this strain of Merinos was under the control of a dominant gene, designated GSHL (Tucker et al. 1976). In contrast, Board, Roberts & Evans (1974) reported that a similar type of GSH deficiency in Australian Merino sheep was under the control of a recessive gene. The reasons for this apparent discrepancy remain unresolved.