The E. coli enzyme β-glucuronidase (GUS) is widely used as a reporter in plant gene expression studies. But its value in other systems is limited by its sensitivity to aldehyde fixatives, and the endogenous activity of many organisms. On page 696, Ellington and colleagues extend the range of GUS by DNA shuffling. They evolved an aldehyde-resistant variant that can be used in formerly recalcitrant organisms like Xenopus, and that can be combined with other reporters for double-staining.