1. School of Biological and Molecular Sciences, Oxford Brookes University, Headington, Oxford, OX3 0BP, U.K.
2. Bass Brewers Limited, Research Laboratory, Bass Technical Centre, P.O. Box 12, Cross Street, Burton-on-Trent, DEM 1XH, U.K.
3. Bass Brewers Limited, Tower Brewery, Wetherby Road, Tadcaster, North Yorkshire, LS24 9S, U.K.