1. University of Medicine of Göttingen, 37075 Göttingen, Germany
2. Institute of Biophysics Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-902, Brazil
3. Institute of Biological Sciences, Universidade Federal de Minas Gerais (ICB/UFMG), Belo Horizonte 31270-901, Brazil