1. Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
2. Present address: Department of Molecular Biology and Microbiology Tufts University School of Medicine, Boston, MA, USA
3. Present address: Department of Biology, Haverford College, Haverford, PA, USA
4. Present address: Department of Biological Sciences, Wellesley College, Wellesley, MA, USA
5. Present address: Institute for Medical Engineering and Science, Department of Biological Engineering, and Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA, USA
6. Present address: Broad Institute of MIT and Harvard, Cambridge, MA, USA
7. Present address: Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, USA
8. Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA