1. Division of Biological Sciences, Cornell University, Ithaca, New York 14853
2. Fachbereich Biologie, J. W. Goethe Universität Frankfurt, Frankfurt-am-Main, West Germany
3. Division of Biological Sciences, Cornell University
4. Fachbereich Biologie, J. W. Goethe Universität Frankfurt
5. School of Dentistry, State University of New York, Stony Brook 11790