1. D. Ilver, Department of Microbiology, Umeå University, SE-901 87 Umeå, Sweden.
2. A. Arnqvist, Department of Microbiology and Department of Oral Biology, Umeå University, SE-901 87 Umeå, Sweden.
3. J. Ögren and T. Borén, Department of Oral Biology, Umeå University, SE-901 87 Umeå, Sweden.
4. I.-M. Frick, Department of Cell and Molecular Biology, Lund University, SE-221 00 Lund, Sweden.
5. D. Kersulyte, E. T. Incecik, D. E. Berg, Department of Molecular Microbiology, Washington University Medical School, St. Louis, MO 63110, USA.