1. Department of Zoology (M.B., P.T.B., V.L.T.), University of Aberdeen, Aberdeen, AB24 2TZ, United Kingdom;
2. Department of Molecular and Cellular Biology (M.B., P.T.B., K.D.), Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, United Kingdom
3. Department of Biological Sciences (J.P.C.), University of Alberta, Edmonton, Alberta, T6G 2E9, Canada;