1. Laboratory of Comparative Endocrinology, K. U. Leuven, Zoological Institute (C.H.J.V., K.V., T.S., E.R.K., S.V.d.G., V.M.D.), B-3000 Leuven, Belgium
2. Laboratory of Endocrinology, Academic Medical Center (O.B., B.Z.D.), 1105 AZ Amsterdam, The Netherlands
3. Department of Cellular and Molecular Physiology, University of Massachusetts Medical Center (J.L.B.), Worcester, Massachusetts 01655