Post by Evil Yoda on Feb 23, 2015 14:36:51 GMT -5
CRISPR - clustered regularly interspaced short palindromic repeats - are sequences of base pairs in the DNA of certain microorganisms. They are repeated collections of base pairs, separated by varying 32 base sequences. Discovered in the late 80s, their function was a mystery until scientists realized the 32 base pair sequences matched sequences found in the DNA of certain viruses. From there, experimentation revealed that these sequences essentially formed a library the bacteria used to identify viral invaders. It manufactures RNA and an enzyme, and turns them loose. They drift in the cell until and unless they encounter a matching sequence - the DNA of an invading virus. The enzyme then cuts the virus, preventing it from reproducing.
It's been known for awhile that bacteria can fight viral invades in a general way with restriction enzymes (discovered in the 70s, a discovery that earned those scientists a Nobel Prize), but CRISPR is the first glimmer that bacteria have something like what we humans have: adaptive immunity. This kind of immunity learns from antigens presented to it; this is why we may catch measles as a child but will never catch it again as long as our immune system functions.
Restriction enzymes are the basis for modern DNA amplification and sequencing - one of their discoverers, Hamilton Smith, eventually joined Craig Venter at Celera and was part of the team that sequenced human DNA. But they are crude by comparison with CRISPR. They cut DNA at arbitrary places, and they cut it all. CRISPR sequences cut only recognized DNA and only at specific places.
Scientists have already (in 2013) replaced defective DNA in mice, curing them of genetic disorders. And they have done this in human cells. Most of the remaining worst diseases, those whose causes are well understood, are genetic. A means of editing out bad genes, replacing them with good copies, or of adding missing genes, would be a true medical breakthrough.
Article
It's been known for awhile that bacteria can fight viral invades in a general way with restriction enzymes (discovered in the 70s, a discovery that earned those scientists a Nobel Prize), but CRISPR is the first glimmer that bacteria have something like what we humans have: adaptive immunity. This kind of immunity learns from antigens presented to it; this is why we may catch measles as a child but will never catch it again as long as our immune system functions.
Restriction enzymes are the basis for modern DNA amplification and sequencing - one of their discoverers, Hamilton Smith, eventually joined Craig Venter at Celera and was part of the team that sequenced human DNA. But they are crude by comparison with CRISPR. They cut DNA at arbitrary places, and they cut it all. CRISPR sequences cut only recognized DNA and only at specific places.
Scientists have already (in 2013) replaced defective DNA in mice, curing them of genetic disorders. And they have done this in human cells. Most of the remaining worst diseases, those whose causes are well understood, are genetic. A means of editing out bad genes, replacing them with good copies, or of adding missing genes, would be a true medical breakthrough.
Article