[1] Department of Applied Biology, University of Wales, Institute of Science and Technology, PO Box 13, Cathays Park, Cardiff,CFI 3XF, United Kingdom
[2] Amersham International PLC, Cardiff Laboratories, Forest Farm, Whitchurch, Cardiff,CF4 1ZZ, United Kingdom
[3] Biotechnica Ltd, 5 Chiltern Close, Llanishen, Cardiff, United Kingdom