Optogenetics – A Primer.

Now before we get started, I cannot tell you enough how cool this field is! I hope to substantiate that claim with some extraordinary demonstrations of the concept to go with a simple description.

The term Optogenetics is a fusion of the prefix Opto (related to light) and Genetics (study and manipulation of genes). This should tell you that the field involves the coupling of the study and manipulation of genes to an external control source using light.

Perhaps the most prominent example of optogenetics involves the use of genes and light to control the function of neurons or nerve cells. Basically, neurons conduct electrical impulses through gradients of ions like chloride and potassium and sodium and so on…in other words, if you alter the gradients of these ions you can get a neuron to “fire” (or propagate an electrical impulse)

This process of conduction has been illustrated here

Now, here is where optogenetics comes in, there needs to be a mechanism of getting ions in and out of cells in response to light. The thing with genes and the fact of a nigh on universally conserved genetic code is that a straight port of genes is possible from organisms of different species and they will always produce the same product.

In the application I’m talking about, they used proteins that pumped ions in and out in response to blue and yellow light, taken from a green alga called Chlamydomonas reinhardtii and an egyptian archaebacterium.

They managed to express those genes and consequently those proteins in specific cells using tissue specific promoters…wondering what those are?

Well, every gene has a region that tells the cell that there is a gene that follows, and tells the cell to make mRNA from the DNA of the gene, while also regulating the process. It is also a fact that some genes are specifically expressed in some tissues and some cells, if you take a promoter of such a gene, and fuse it to a gene of your interest, you can get it to form protein only in those tissues/cells.

This enables light to be introduced through fibre optic cables with a bit of a scattergun approach, and also enables the response to be accurately controlled. In other words, we can switch neurons on and off, mind control here we come mwahahaha 😉

Generalized protocol

Well, we really do.

The following lecture discusses what I’ve described above and has lovely illustrations, too.

These experiments were carried out in the lab using cell cultures in Petri dishes and in model organisms in the laboratory, including rats and mice, it wouldn’t surprise me if technologies such as this eventually found applications in humans, given the potential it has.

A small sampling of the peer reviewed literature on the subject follows.

Molecular and cellular approaches for diversifying and extending optogenetics

The Dawning of Primate Optogenetics

Photofunctional proteins: from understanding to engineering

The optogenetic catechism

Happy reading 🙂

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