About the Authors
Genome Institute of Singapore, Singapore
Department of Biology, San Diego State University, San Diego, California, United States of America
The authors have declared that no competing interests exist.
FR and YR conceived and designed the experiments. TZ, MB, JR, CLW, SWLS, and FR performed the experiments. TZ, MB, WHL, SWLS, and YR analyzed the data. TZ and YR wrote the paper. MB, MLH, ETL, and FR helped revise the paper.