[1] Univ Nacl Autonoma Mexico, Inst Fisiol Celular, Dept Mol Genet, Mexico City 045510, DF, Mexico
[2] Univ Munich, Inst Physiol Chem, D-81377 Munich, Germany
[3] Univ Nacl Autonoma Mexico, Inst Biol, Dept Bot, Mexico City 04510, DF, Mexico
[4] Cornell Univ, Dept Mol Biol & Genet, Ithaca, NY 14853 USA