[1] UNIV CALIF BERKELEY, DEPT MOLEC & CELL BIOL, BERKELEY, CA 94720 USA
[2] UNIV STOCKHOLM, DEPT GENET, S-10691 STOCKHOLM, SWEDEN
[3] UNIV OSLO, CTR BIOTECHNOL, N-0317 OSLO, NORWAY
[4] UNIV OSLO, INST BIOL, N-0317 OSLO, NORWAY
[5] UNIV IOWA, SCH MED, DEPT MICROBIOL, IOWA CITY, IA 52242 USA
[6] LAB MICROBIAL GENE TECHNOL, N-1432 AS, NORWAY
[7] NIH, NATL LIB MED, NATL CTR BIOTECHNOL INFORMAT, BETHESDA, MD 20894 USA