Morpholino

 -Small oligomer of synthetic nucleotide analogues that block gene expression

-25bp length
-attaches to mRNA, pre/mature, to cause gene knockdown

-Used as gene knockdown tools on zebra fish   

On mature:
-attach to AUG blocking ribosome interaction

On pre-mRNA:
-sits on splice site, an intron-exon junction, making a double stranded RNA, blocking spliceosome which will create truncated/no protein

Shukla, Arun K., editor. “The Zebrafish: Disease Models and Chemical Screens.” Methods in Cell Biology, vol. 105, no. 12, 2011, pp. 273–308., doi:10.1016/c2009-0-62387-4.