After digestion by restriction endonucleases DNA bands can re-joined by which of the following substance?

DNA ligase is used to join the DNA bands formed after digestion by restriction endonuclease. DNA gyrase: Its a special type of topoisomerase, has the unusual propey of being able to introduce negative supercoils into resting DNA. This facilitates the future replication of DNA because the negative supercoils neutralise the positive supercoils introduced during opening of the double helix.