Scientists investigating an important DNA-repair enzyme now have a better picture of the process that glues together, or ligates, the ends of DNA strands to restore the double helix. The enzyme, DNA ligase (shown in color, encircling the DNA double helix), repairs the millions of DNA breaks generated during the normal course of a cell's life. DNA is under continuous assault from environmental toxins and reactive cellular compounds. A means of repairing DNA damage is vital to maintaining the integrity of the genetic blueprint.