Cara H Haney1, Frederick M Ausubel2. 1. Department of Genetics, Harvard Medical School, Boston, MA 02114, USA. Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA. haney@molbio.mgh.harvard.edu. 2. Department of Genetics, Harvard Medical School, Boston, MA 02114, USA. Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA.