Hop, skip and jump

From ancient fish genes geneticists have reconstructed a stretch of DNA that can "hop' in and out of chromosomes. This gene could expedite the development of gene therapy to tackle diseases. Such mobile genetic units (called transposons) are usually found in insects and worms. Transposons, only a few thousand base pairs long, contain the enzyme transposae, that snips out and inserts them elsewhere on the chromosome. Perry Hackett, molecular geneticist at University of Minnesota, usa, and a team from Netherlands Cancer Institute, Amsterdam, have aligned two dozen transposon fragments and rebuilt an operational fish transposon. This new gene unit, baptised Sleeping Beauty, was successfully tested on human and mouse cells. The team "sprinkled' bits of dna containing Sleeping Beauty onto the cells, which took up the genetic material. The cells then expressed the transposae gene and Sleeping Beauty awoke, hopping out of the added dna and into the chromosomes ( New Scientist , Vol 156, No 2109).