For my first subject, I want to talk about this thing called CRISPR (pronounced “crisper”), which is causing a lot of excitement among biologists and biochemists. The first time I heard about CRISPR was on the JRE podcast, which led me to another podcast called Radiolab. Most of what I'm writing in this post is a worse version of the explanations given in the podcast. So, if you are interested on the subject, and you want a longer explanation about it, I highly recommend Radiolab.
Before I go on, let me be clear that I am not a biochemist, and this is just my ignorant explanation of the subject. CRISPR stands for “clustered regularly interspaced short palindromic repeats”. If you are not a biologist (like me) the acronym description did not help that much. So, let me try to explain it. Apparently people have known about CRISPR since 1987 when a Japanese scientist Yoshizumi Ishino published a paper about the subject. The Ishino’s group found in a bacteria called E. coli (Escherichia coli) repeated sequences of DNA, essentially, five repeated sequences with some bits of DNA in between, which is a very unusual thing to find in bacteria. At first, nobody really cared about it back then because they thought it was "junk DNA". However, later, they started finding this repeated sequences of DNA in a lot of different bacteria.
Some years later, around 2005, with the advances in biotechnology, algorithms, and hardware, scientist were able to apply match algorithms in their huge DNA databases containing information of various species, and they found that the bits of DNA in between the repeated sequences were actually virus DNA. In other words, they found virus DNA information inside another specie. The crazy thing is that some brilliant scientist named Eugene Koonin interpreted these findings as a defense mechanism developed by the bacteria to protect themselves against viruses. He hypothesized that the bacteria were storing these pieces of DNA to be able to identify virus later on when they get attacked again. By doing that, they could recognize the enemy right away, and send the right defense troops. The way the defense soldiers go about finding the virus DNA is to compare the stored DNA (copy of a virus) with the all the viruses DNA until they find the right match. Once they find the right match, they cut the exact piece of DNA with their molecular scissors, and kill the virus.
Scientist Jennifer Doudna was fascinated by this mechanism of finding and cutting the right sequence of DNA, and she visualized this as a tool to be used to cut DNA exactly where they want to. However, her idea was to use the soldiers to find bad genes like the ones that cause things like hemophilia, cut exactly that sequence, and replace it with a good gene sequence. This mechanism can be seen a way to engineer things. In fact, genetic engineering has been around for a long time, but nothing so far is as powerful as CRISPR. The old technologies were very expensive, and had unpredictable results, whereas CRISPR is very cheap and precise. On top of that, this technique can be used possibly in any specie.
This molecular scissors that can cut DNA cheaply and precisely is essentially a genome-editing tool that has a lot of possibilities. On part 2, I will discus the crazy different possibilities that CRISPR can enable.