Editing Exon (section)

==Experimental approaches using exons==
[[Exon trapping]] or '[[gene trapping]]' is a [[molecular biology]] technique that exploits the existence of the intron-exon [[RNA splicing|splicing]] to find new genes.<ref>{{cite journal |author1=Duyk G. M |author2=Kim S. W. |author3=Myers R. M |author4=Cox D. R | year = 1990 | title = Exon Trapping: a Genetic Screen to Identify Candidate Transcribed Sequences in Cloned Mammalian Genomic DNA | journal = Proceedings of the National Academy of Sciences | volume = 87 | issue = 22| pages = 8995–8999 | doi=10.1073/pnas.87.22.8995|pmid=2247475 |pmc=55087 |bibcode=1990PNAS...87.8995D |doi-access=free }}</ref> The first exon of a 'trapped' gene splices into the exon that is contained in the [[insertional DNA]]. This new exon contains the ORF for a [[reporter gene]] that can now be expressed using the [[Enhancer (genetics)|enhancer]]s that control the target gene. A scientist knows that a new gene has been trapped when the reporter gene is expressed.

Splicing can be experimentally modified so that targeted exons are excluded from mature mRNA transcripts by blocking the access of splice-directing small nuclear ribonucleoprotein particles (snRNPs) to pre-mRNA using [[Morpholino|Morpholino antisense oligos]].<ref>{{cite journal |author=Morcos PA |title=Achieving targeted and quantifiable alteration of mRNA splicing with Morpholino oligos |journal=Biochemical and Biophysical Research Communications |volume=358 |issue=2 |pages=521–7 |date=June 2007 |pmid=17493584 |doi=10.1016/j.bbrc.2007.04.172}}</ref> This has become a standard technique in [[developmental biology]].  Morpholino oligos can also be targeted to prevent molecules that regulate splicing (e.g. splice enhancers, splice suppressors) from binding to pre-mRNA, altering patterns of splicing.