Using Microinjection of Xenopus Oocytes to Express and Optimize Ribozymes In Vivo

Although it appears to be relatively easy to design ribozymes that cleave their targets and produce detectable cleavage products in vitro, especially when both molecules are quite small, the detection of cleavage products in viva has been remarkably difficult. It is generally assumed that the cleavage products are very unstable and experimenters have tended to look for overall decreases in target RNA levels or to examine the effects on protein levels or on biological activity (e.g., resistance to HIV replication). In some cases where an apparent ribozyme effect has been claimed, it is therefore possible that inhibition may be due to factors other than cleavage of the target by ribozyme.