 Up to 18 % of Morpholinos appear to induce nontarget @-@ related phenotypes including cell death in the central nervous system and somite tissues of zebrafish embryos . Most of these effects have been shown to be due to activation of p53 @-@ mediated apoptosis , and can be suppressed by co @-@ injection of an anti @-@ p53 Morpholino along with the experimental Morpholino ; moreover , the p53 @-@ mediated apoptotic effect of a Morpholino knockdown has been <unk> using another antisense structural type , showing the p53 @-@ mediated apoptosis to be a consequence of the loss of the targeted protein and not a consequence of the oligo type used to knock down the protein . It appears that these effects are sequence @-@ specific ; as in most cases , if a Morpholino is associated with non @-@ target effects , the 4 @-@ base mismatch Morpholino will not trigger these effects . 
