1. Department of Chemistry, Bowling Green State University, Bowling Green, OH 43403, USA
2. Center for RNA Biomedicine, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
3. Architecture et Réactivité de l’ARN, Université de Strasbourg, Institut de Biologie Moléculaire et Cellulaire du CNRS, Strasbourg France
4. Department of Mathematics and Statistics, Bowling Green State University, Bowling Green, OH 43403, USA