1. Interdisciplinary Biochemistry Program, Indiana University, Bloomington, IN 47401, USA.
2. Carnegie Institution of Washington, Washington, DC 20015, USA.
3. NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD 20771, USA.
4. Facultad de Ciencias, Universidad Nacionale Autónoma de México, Mexico Distrito Federal 04510, Mexico.
5. Scripps Institution of Oceanography, La Jolla, CA 92093–0212, USA.