Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA. dfowler@uw.edu|Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA. dfowler@uw.edu|Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA. dfowler@uw.edu|Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA. dfowler@uw.edu