Developments in the hammerhead ribozyme field during the last two years ape
reviewed here. New results on the specificity of this ribozyme, the mechan
ism of its action and on the question of metal ion involvement in the-cleav
age reaction are discussed. To demonstrate the potential of ribozyme techno
logy examples of the application of this ribozyme for the inhibition of gen
e expression in cell culture, in animals, as well as in plant models are pr
esented. Particular emphasis is given to critical steps in the approach, in
cluding RNA site selection, delivery, Vector development and cassette const
ruction.