The invention encompasses methods for improving the level and/or sustainability of expression for a target nucleic acid in a eukaryotic cell comprising: (a) modifying the target nucleic acid to introduce or to comprise signals that limit or constrain the positions of nucleosome cores, and (b) introducing the modified target nucleic acid into the eukaryotic cell, wherein the modified target nucleic acid has improved levels and/or sustainability of expression compared to original unmodified nucleic acid.