1. Pharmacia and Upjohn, Animal Health Discovery Research, Kalamazoo, MI 49007, USA
2. Division of Biology, Kansas State University, Manhattan, KS 66506, USA
3. Wadsworth Center, NY State Department of Health, David Axelrod Institute, Albany, NY 12201-2002, USA
4. Botany Department, University of Georgia, Athens, GA 30602-7271, USA
5. Pace University, Haskins Laboratories, 41 Park Row, New York, NY 10038-1598, USA