Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.|Howard Hughes Medical Institute and Biology Division, California Institute of Technology, Pasadena, CA 91125, USA.