Before revision:  The mechanism is called endonuclease dependent transcript cutout  , in which a copy of ssDNA fragment (transcript) between two nicks produced by nicking endonuclease is released from double-stranded DNA region in the genome by an unknown ssDNA fragment-releasing enzyme.
After revision:  The mechanism is called endonuclease dependent transcript cutout , in which a copy of ssDNA fragment (transcript) between two nicks produced by nicking endonuclease is released from double-stranded DNA region in the genome by an unknown ssDNA fragment releasing enzyme.