From another blog this date.
Reading this week:
- Matt Ridley's Genome, 1999; and,
- The Code Breaker: Jennifer Doudna, Gene Editing, and the Future of the Human Race, Walter Isaacson, c. 2021. Notes here.
- an early post on CRISPR: link here. This was back in 2018! Whoo-hoo!
- CRISPR was all the rage in the 2010s. All of a sudden, the acronym is seldom heard/read in mainstream media.
I had forgotten I wrote this in 2018:
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Bonus Note For The Granddaughters
Bonus Note For The Granddaughters
CRISPR.
CRISPR-Cas9.
Until this week, I knew nothing of significance about CRISPR. For whatever reason I mentioned CRISPR to our 14-year-old granddaughter on the way to school the other day, and she became incredibly animated. She loved "CRISPR" and knew more about it than I did.
Whatever she knows about CRISPR she learned on her own. I doubt they have yet studied it in high school, although it's possible it's been mentioned
I'll have fun talking to her about CRISPR over the next few weeks.
CRISPR is part of the DNA genome. Back in 1993, a biologist studying bacteria in Spanish swamps, found bacteria whose DNA contained repeated sequences of DNA that did not correspond to anything previously seen.
Because of the nature of these repeated sequences (clusters, regularly interspersed, and short palindromic repeats) he labeled them CRISPR for short.
It turns out that these palindromic repeats of "meaningless" genome were actually pieces of viral DNA -- viruses that had invaded bacteria as pathogens (bacteriophages -- to eat bacteria).
It is hypothesized that by incorporating this "meaningless" viral genome, bacteria are more quickly able to defend against a virus from attacking it (a second time).
And like everything else in biology, there is more to the story.
Molecular biology dogma: DNA makes RNA makes protein.
CRISPER makes RNA but this RNA does not make a protein. By itself, the CRISPR-RNA is worthless.
But, as it turns out, as in a Rudyard Kipling "just so" story, bacteria also contain an enzyme (or protein) called Cas9 -- short for CRISPER-associated protein 9. If the biologists had had a sense of humor, it would be easier to remember as"Mama Cass protein" -- CRISPR-associated protein that loves to eat.
But a very special way of eating.
As noted above CRISPER-RNA by itself is worthless.
But with the Cas9 enzyme "stuff happens." Cas9 enzyme is a "cutter."
CRISPER-RNA guides Cas9 enzyme to the virus with the corresponding DNA genome.
At the viral DNA genome, the Cas9 enzyme gets to work, cutting out the viral genome that corresponds to CRISPR-RNA.
Pretty clever, huh?
Know who connected the dots, figured this out?
A Danish yogurt company. Yup, Danisco -- a Danish yogurt company.
Danisco is now owned by Dow Dupont.
Researchers now use CRISPER-Cas9 to target any region/gene in any DNA genome and cut it out / remove it. By removing a gene, researchers are better able to discern the purpose of a previously non-understood gene.
If a bacteria is able to do what a bacteria normally does and now loses a certain function because it has lost a certain gene, scientists have a pretty good idea of what that gene must be responsible for.
Likewise, researchers can do that to any mammalian genome.
Much, much more to the story but I now have enough to share with our granddaughter and still be able to keep up with her.
This was from "Diary" in the current issue of London Review of Books. Another source is here.
That 14-year-old granddaughter is now a sophomore STEM student at Stanford University, California, ROTC.
