Bacterial Mechanoreceptors

[Sebastian S. Cocioba]

In the process of studying rapid movement in plants, I stumbled upon a large research field in the topic of mechanosensitive ion channels in bacteria. The concepts between bacterial and plant shock sensing is similar in that they both release or take in an ion as a secondary messenger as a result said shock. I am curious if any DIY Bio or iGEM ppl worked with this concept and, lets say, tie it to gfp expression so one could make a tap sensitive glow under UV? A genetic momentary switch of sorts. Just curious...

Sebastian S Cocioba
CEO & Founder
New York Botanics, LLC

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[Nathan McCorkle]

I'd look into the dinoflagelletes as they seem to already do the 'bump and glow' thing (they're closer to your plants too)

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[Ben Hunt]

I like the idea of a plant user interface. They're big enough to mash around without killing them, and (most) don't leave a stinky residue on your hands. I think expression is pretty slow though. 

Maybe you could activate an already expressed but dormant enzyme to chew up some proteins that have been crammed into a cellular compartment so hard that they are unfolded? Or maybe there is a blockable luciferase . . .

[Nathan McCorkle]

On Tue, Dec 18, 2012 at 10:32 AM, Ben Hunt <ben.g...@gmail.com> wrote:

I like the idea of a plant user interface. They're big enough to mash around without killing them, and (most) don't leave a stinky residue on your hands. I think expression is pretty slow though. 

Expression may be slow, but if the system is already expressed but in a 'waiting' state it can be quite fast, look at mimosa pudica and venus flytraps, in the 10s or 100s of milliseconds from touch to mechanical twitch. 

I think it'd be cool to have the plant act as an electrical button interface that self-cleaned, put in public and it could reduce disease transmission. You'd need to instead of mechanical twitch, light up, or depolarize a 'nerve' tract in the stem that you could clamp a sensor onto. 

 

[Graeme Dean]

Hi, Just wondering, If you are going to try making something tap sensitive have you thought about working with something like Mimosa pudica? I have done a small amount of looking and have not found much, I  would be very curious about anything people have to say or have found/are doing on this subject. 

[Sebastian S. Cocioba]

My original goal was to try to cassette the mechanoreceptor genes from mimosa pudica but the issue is that the system in question is A). Poorly understood, and B) relies on turgor pressure loss of specific cells called pulvini motor cells. It involves very specific tissues acting like hinges and once hydraulic pressure lost the leaf or branch moves. I think dinos are the way to go. From what I know the dinos respond to bumping by hair like triggers on their surface. I am looking for a simple structure that will change conformation once touched or bumped and induce some gene expression down the line that can be exploited into a controllable switch with gfp expression as its verification packet. Thanks Nathan for the tip. Will keep posted on any findings.

Sebastian S Cocioba

CEO & Founder

New York Botanics, LLC

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[Cathal Garvey]

This mechanism matches well with that used by Dionaea muscipula (Venus
Flytrap): the closing of the traps is accomplished by expansion of the
outer layer of the trap/leaf tissue, not by contraction of the inner
layer. Unlike Mimosa pudica it's a one-way issue, apparently traps are
usually only good for 3-6 rounds of trapping, but they get bigger with
each cycle of opening and closing.

And, like M.pudica, it's an ion/osmosis influx mechanism, though I read
about it in a dead-tree book so long ago that I can't provide a citation
or even a guarantee of which ion is involved.

In other news, I actually have seeds for M.pudica, but never bothered
sprouting them; I've heard it's a really annoying plant to cultivate and
takes ages to grow. A friend has one, and I've poked it for fun; very
satisfying! But, according to her it's languishing in the Irish climate
and probably won't survive another year. :-/

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[Sebastian S. Cocioba]

M. Pudica takes 5 days to sprout after a 24hr soak in hot water and 10 days till first contractile touch. Just keep it indoors under a standard desk light. If you want to get fancy keep it at 8000 lux with a 16hr photoperiod for optimal growth. It actually grows fast since it is a weed but needs warmth so indoors is ideal. The ion in question is Ca++ and it is stored in a separate tannin vacuole denoted by redish pigmentation near the base or the leaf and intersection of the branch to the main stem. Just FYI.

Sebastian S Cocioba
CEO & Founder
New York Botanics, LLC

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[Patrik D'haeseleer]

Hi Sebastian,

It wasn't clear to me whether you want mechano*receptors*, or some sort of mechanical *actuators*. You seem to switch between the two indiscriminately, but those are two very different systems. For example, as far as I know the pulvini cells in mimosa are only actuators: they create movement. The dinoflagellates on the other hand do not have any actuators - they are not motile, and respond to mechanical shear forces with a flash of bioluminescence.

Mechanotransduction in dinoflagellates is still poorly understood, and may not be compatible at all with genetic engineering into bacteria. For one, it presumably requires an algal cell wall. Heck, mechanotransduction is still very poorly understood in general. In fact, there's probably way more known about how mechanosensing works in mammalian touch receptors, or in the hair cells in the inner ear, than in dinoflagellates - and those will probably be equally hard to engineer into bacteria.

[Sebastian S. Cocioba]

My apologies for the lack of clarity. I would like to study the genes involved in sensing mechanical signals and/or stress in plants. Not the actuation itself but the signal transduction from the stimuli to the end reaction/response. In short I'm looking for any potential leads for the development of touch sensitive gene expression in plants. Ideally like dino's touch and glow system. The genetic momentary switch.

Sebastian S Cocioba

CEO & Founder

New York Botanics, LLC

Sent via Mobile E-Mail 

To view this discussion on the web visit https://groups.google.com/d/msg/diybio/-/3kACKKyO6woJ.

[Patrik D'haeseleer]

Ah - and is there anything known about that mechanism in Mimosa or the Venus Flytrap? I assume this is entirely separate from the pulvini motor cells, right?

I believe the fast responses in Mimosa, Venus fly trap, and dinoflagellates all involve action potentials, which might be tricky to intercept. If you don't require an almost instantaneous response, you could make your life much easier. For example, there are known wound response systems in all plants that you could tap into. There's also some MAPK signal transduction pathways that you could redirect to turn on some reporter genes.

If you want a very fast response, you need to aim for something that works completely at the electrochemical level (like the action potential triggered events in Mimosa or dinos) or at least post-translationally (e.g. activating an enzyme by phosphorylation). Somewhat slower would be something that acts at the post-transcriptional level, e.g. riboswitches that turn on translation of an enzyme from an existing mRNA. Slowest of all would be something that works at the transcriptional regulation level, that is, by turning on or off expression of specific genes. The latter is easiest to engineer so far, but there's lots of research being done on riboswitches right now.

Patrik

[Sebastian S. Cocioba]

Thanks for all your insight, Patrik. From what I have read so far. There are some shock sensing calcium ion channels on the surface of the tannin vacuoles that pump out the calcium in response. The calcium acts as a secondary messenger that activates a downstream turgor pressure change which is also ionically driven. This is where things get grey since little is known about what the pathway consists of. Almost all of the research done is on Mimnosine biosynthesis since it is an apototic agent and useful against a certain type of cobra venom. Nothing else is listed in genbank from what I have dug up. Some pulvini systems from the pea family, which cause the thigmonastic response of closing leaves at night have roughly the same system which do not involve hair triggers like the VFT. Ideally the response I am hoping for is much like the dino's glow response speed- instant. I will look into all of the possibilities you have mentioned. Thanks agin! :D

Sebastian S Cocioba

CEO & Founder

New York Botanics, LLC

Sent via Mobile E-Mail 

To view this discussion on the web visit https://groups.google.com/d/msg/diybio/-/RlLAE6LWWP0J.