Morpholinos

 Morpholinos are small oligomers that are roughly 25 base pairs long, and they are used to block gene expression. They are similar to DNA and RNA in structure and how they work, but  posses a different back bone which is non ionic.

This non ionic back bone also means that morpholinos are less likely to interact non selectively with cellular proteins, and due to their back bone being different of that of a nucleic acid, it means that enzymes that interact with nucleotides (nucleases) do not break it down and they are not degraded by cells.

They use Watson-Crick base pairing and bind to complementary nucleic acids. The morpholinos can be used in variety of techniques such as translation blocking, they do this by binding to complementary base pairs on RNA and so stoping protein synthesis at the blocked sites. They can also be used for splice modification whereby they can change to mRNA product by interfering with the splicing of the pre-mRNA (this usually happens by deletion of an exon). The morpholinos also prevent microRNA from reaching its mature and active form by blocking the Dorsha or Dicer cleavage sites.

Morpholinos are being used in experiments carried out on Zebra fish and the Clawed toad to block certain gene expressions. Human clinical trails are being done to try and find ways of blocking certain diseases and also for use of blocking replication of many viruses.