[1] Nestle Res Ctr, CH-1000 Lausanne 26, Switzerland
[2] Univ Nova Lisboa, ITQB, P-2781901 Oeiras, Portugal
[3] Univ Jyvaskyla, Dept Biol Environm Sci, FIN-40014 Jyvaskyla, Finland
[4] CNRS, UMR 5100, Lab Microbiol & Genet Mol, F-31062 Toulouse, France
[5] Univ Toulouse 3, F-31062 Toulouse, France
[6] Univ London Imperial Coll Sci Technol & Med, Dept Mol Microbiol & Infect, London SW7 2AZ, England
[7] CSIC, Ctr Nacl Biotecnol, E-28049 Madrid, Spain
[8] INRA, Lab Genet Microbienne, F-78352 Jouy En Josas, France
[9] Max Planck Inst Infect Biol, RNA Biol, D-10117 Berlin, Germany