About the Authors
Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
Howard Hughes Medical Institute, University of Utah, Salt Lake City, Utah, United States of America
The authors have declared that no competing interests exist.
MH, MTP, and EMJ conceived and designed the experiments and wrote the paper. MH, MTP, SW, and SO performed the experiments. MH, MTP, SW, and EMJ analyzed the data.