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Comment by JunkDNA | Hacker News Reader

This is fascinating but unsurprising given all the things that have come out lately with regard to epigenetics. If your mental model of DNA involves some image of a pristine blueprint that is followed with clockwork-like precision in the exact same way by every cell in your body, your model needed updating quite some time ago.

I feel that many researchers, even geneticists who should know better, still have not internalized the idea that epigenetics is pretty good evidence that somatic DNA is a read/write medium. This leads to sloppy thinking about genetic causes of disease as well as continued persistence of the idea that if we can just collect enough sequences, all genetic causes of disease might be found.

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The DNA doesn't sport standard read/write access, what's happening is that the expression or not of some genes can occur on an individual and be inherited by its offspring. The DNA doesn't change (save for the chance of a tiny few random changes, as usual)...

(de)methylation is DNA read/write. The DNA does change, although the sequence of bases doesn't.

Methylation is like setting a preference in a config file.

In the situation described by the article, the changes in gene expression are happening in the rat's brains. These changes aren't going to make it into the rat's gametes.

My understanding seems to be at conflict with how I'm reading your description here. Please help me out?

DNA is comprised of four specific nucleic acids which are always the same molecular combination. These acids form into base-pairs which must always be some combination of those four acids.

The DNA itself cannot be 'written to' as if it stores information no less than the following string x = "ACGTACT" can contain additional information beyond those bytes already stored in the string. We could alter the DNA, just as we can alter the string x, but this isn't writing additional data to the binary values, but changing what's stored in those memory locations.

When we're talking about reading/wrting to the DNA, are we actually speaking about modifying the sequence of any given strand, thus "reading/writing to DNA" is a misnomer ? I know there are presently ways to produce DNA synthetically, but what you've said seems to indicate there's room here for any pre-defined sequence I print to end up doing different things in a cloned cell than their synthetic duplicates might.

To cite Kwikipedia on the Epignetics article: http://en.wikipedia.org/wiki/Epigenetics

[Epigenetics] refers to functionally relevant modifications to the genome that do not involve a change in the nucleotide sequence.

There was an eye opening documentary on the subject produced by BBC Horizon a few years ago: The Ghost in your Genes, http://www.youtube.com/watch?v=ehwFVgQ82ZY

This is very cool, thank you for sharing. I've been on-and-off involved in some synthetic biology FOSS software, but as a non-biologist so much of this is hard to keep up with and make informed decisions about.

what's the FOSS software you're involved with? My synthetic biology nonprofit would be very interested.

The "epigenetics" they're talking about is the chemical modification of the DNA. So while we usually talk about sequences of A,T,G,C we've actually got an additional symbol e.g. M. Which might be "methylated C".

So, these "base modifications" are actually increasing the alphabet size, you have the normal A,T,G,C bases and then a set of modified bases.

>I know there are presently ways to produce DNA synthetically, but what you've said seems to indicate there's room here for any pre-defined sequence I print to end up doing different things in a cloned cell than their synthetic duplicates might.

yes, or they might get modified so they are similar to the sequences already present.

By this argument, culture can be imprinted into DNA too, no?

This also implies that it would be much tougher to do a Jurassic Park recreation, because the environment is different. You can't just start from scratch with the DNA.

Or am I misinterpreting?

You are absolutely correct.

It's a mistake to think there is only one correct path when talking about DNA. Often, there is quite a bit of redundancy involved so Jurasic Park dinosaurs may be slightly different than there historic counterparts but that would not prevent them from being sufficiently viable to pass on there DNA. Because, biology is PASS / FAIL not some pursuit of perfection.

You are misinterpreting. As others have noted, this is DNA in the nuclei of nerve cells, not gametes. It is not heritable.

This, thank you. People often forget about this when they are thinking about environmental elements modifying DNA.

Although the primary structure of DNA remains unaltered it is still possible for the environment to alter the traits of offspring: http://en.wikipedia.org/wiki/Transgenerational_epigenetics

Culture is related to implicit and explicit memories shared by many people.

So (supposing that the results of this study can be generalized), yes, culture ends up imprinted in neuronal DNA, one cell at a time.

Since the imprinting is distributed and varies among the billions of neurons in your head it will not be passed to descendants (which inherit half a cell's worth of DNA).

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