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Brain Cells Share Information with Virus-Like Capsules (theatlantic.com)
126 points by bryanrasmussen on Jan 13, 2018 | hide | past | web | favorite | 23 comments

Never underestimate the bandwidth of a virus full of RNA.

I guess this is the biological equivalent of mailing hard disk.

Yup. For the benefit of anyone who didn't hear of the original quote yet: "Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway" (Andrew Tannenbaum)


This gets towards an answer to the question I've always posed to computer scientists seeking to emulate brain function in a program: what is the basic unit of memory?

When you drill down to the fundamentals of computer science you get to the bit; all complex data is essentially a representation on top of bits. I've always wondered what the quantum of human memory is though. What's the smallest thing that you can remember?

I always think about this because my living memories are rich-media with sound and sight and smell and feel. I suppose facts can be a smaller bit of memory, but how is that actually encoded? Maybe we'll know in our lifetimes, maybe not.

How do you define memory?

If you mean, "knowledge of the past" then even the simple neural nets of today exhibit memory when they can recognize your face.

So where does this face recognizing neural net store information about eyes, ears, noses, etc? That information is part of the neural net but it's distributed across all the neurons.

This type of memory system is much closer to how memory in the real brain works.

But what if that's only one mechanism? What if some information is stored in DNA or RNA? And what if that can be copied and stored in other cells too? What if each neuron could store even kilobits of data in it's DNA? Capacity per neuron goes up by a few orders of magnitude.

Have you read "In Search of Memory" by Kandel? It's half autobiography half exploration of that question. His studies on this topic won him a Nobel, and his life story is fascinating to boot!

Lynn Margulis was a huge proponent of the idea that speciation happens mostly via symbiogenesis and cross-species gene transfer as opposed to natural selection. This virus-like cell, while admittedly still not well understood, seems like the kind of thing she would point to as an example of different forms of life merging to create new higher-level lifeforms.

disclaimer: only read the abstract. The original paper, linked in the article mentions the mRNA messaging. Intuitively that roughly makes sense -- other cells might have the luxury of being able to directly talk to each other, through physical contact or proximity, but with neurons that is made more difficult due to the possibility of extending electric signals. So carrying information through mRNA might work, but I wonder why mRNA? Why not skip the middle man and go straight for proteins? What's the use of doing it this way? ik I'm anthropomorphizing but it seems to make more sense to just send out proteins to communicate? Or maybe mRNA allows for more finetuning on the other end, and is a more efficient mechanism, since it can be read dozens of times, instead of just being a handful of proteins.....

>why mRNA? Why not skip the middle man and go straight for proteins?

There is no polypeptide decoding machinery in the cell, proteins are functional chains with a lot of structure.

However cells do use external protein structure to communicate with neighboring cells (via protein-protein interactions) now we know they can send messages via RNA as well.

it's easy to encapsulate any sequence of mRNA; unless it contains extensive tertiary, while any random sequence of protein is going to fold into an irregular shape and probably also have some catalytic capability (such as proteoltyic) which would degrade the protein coat.

That said, GroEL does that (encapsulates various proteins and refolds them).

And a capsid might be able to store a few proteins, or a few mRNAs. But a few mRNAs deposited into a cell could produce many thousand protiens.

In addition to the reasons already posted, here's another: tuning mRNA degradation rates is something cells are already very good at. If tuning the effective communication distance is desirable, using mRNA would provide a ready-made set of tools to achieve it.

There's no fundamental reason. I expect it was just chance that mRNA evolved as the messenger for this signal. One possibility is that an mRNA signal can be amplified on the receiving end with only basic cell machinery, whereas a protein it other messenger generally requires a dedicated receptor to transduce the signal.

mRNA can be re-used by the target cells. It could be an amplification mechanism (assuming fan-out distribution).

I find biology to be endlessly fascinating. I know this is terribly off-topic but, if you enjoy learning about this kind of information, I'd highly recommend 'The Gene: An Intimate History.' It's a lovely read that brings you from before Mendel up to the brink of modern genetics.

I'd like to hear any other book recommendations people may have related to this topic.

I find everything not made by humans to be completely random. Given unlimited space and eternal time everything is possible.

Maybe this is one reason we haven't become more resistant to viruses? Because we actually need to use them, or something like them, to learn?

What I read from the ya thatvwe inherited certain processes from viruses which they use to infiltrate us, hundreds of millions of years later.

Just to note, this has nothing to do with Hintons Capsule Networks

Is the mechanism of 'Arc' gene related to the dynamic routing process of Capsule networks [1, 2]?

[1] https://kndrck.co/posts/capsule_networks_explained/

[2] https://arxiv.org/abs/1710.09829

It has the same word in it, that's about it. Come on, use your brain a bit

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