Just four letters – A, C, T, and G – make up an organism’s genetic code. Changing a single letter, or base, can lead to changes in protein structures and functions, impacting an organism’s traits. In addition, though, subtler changes can and do happen, involving modifications of the DNA bases themselves. In the May 8, 2017 issue of Nature Genetics, a team led by scientists at the U.S. Department of Energy Joint Genome Institute (DOE JGI), a DOE Office of Science User Facility, report the prevalence of modifications in the earliest branches of the fungal kingdom. Read more at the DOE JGI website.