[HN Gopher] Biological Miracle - Wood Frog
___________________________________________________________________
Biological Miracle - Wood Frog
Author : thunderbong
Score : 474 points
Date : 2024-11-15 18:16 UTC (1 days ago)
(HTM) web link (www.nps.gov)
(TXT) w3m dump (www.nps.gov)
| pwdiscflatmajor wrote:
| I now know why I require so much sugar and sweets: I am a wood
| frog preparing for hibernation!
| sudobash1 wrote:
| There are no pictures of the frogs in this article. For pictures
| (of thawed and frozen frogs) you can see:
| https://shakerlakes.org/frozen-frogs/
| olejorgenb wrote:
| From the linked video: timelapse of the thawing process:
| https://youtu.be/pLPeehsXAr4?t=176
| chasil wrote:
| They also have a wiki, but not many photos. One photo is from
| Quebec.
|
| The wiki also mentions that urea is produced, in addition to
| glucose, and both act as cryoprotectants.
|
| https://en.m.wikipedia.org/wiki/Wood_frog
| nuancebydefault wrote:
| Looks like a normal (frozen) frog to me
| moralestapia wrote:
| Fascinating phenomena, thanks a lot for sharing!
| metalman wrote:
| cant even call that hibernation. There are other knock on
| advantages to bieng frozen solid, it would slow down and even
| kill a lot of infectious microbes.It may convey a certain life
| extension benifit. And threre is not much behavioral adaptation
| needed,frog gets chilly, snuggles under a leaf,freezes solid,
| gets defrosted 8 months later and wakes up hungry and horny, not
| bad.
| duskwuff wrote:
| > it would slow down and even kill a lot of infectious microbes
|
| I wouldn't count on it killing them. The cryoprotectants in the
| frog's body don't discriminate; they'll protect foreign
| bacteria just as well as the frog's cells.
| metalman wrote:
| I should of elaborated, many of the issues associated
| with,"conventional hibernation" have to do with lethal
| infections aquired externaly while hibernating, damp, cold,
| ....mold as to the cryoprotectants ,side protecting microbes,
| clearly gut microbes and other internal flora ,would
| benifit......but ,big but, would a sneeky cryosuspension
| routine also include a freeze and clense cycle?, why not! and
| easy enough to verify,right!
| seesaw wrote:
| I wonder what happens to the gut bacteria ? Do they also
| freeze and get thawed ? If so, are those bacterium also
| having a special adaptation, or is it a function of the
| host ?
| m463 wrote:
| I would imagine the frog's internal ecosystem has co-evolved
| with lots of bacteria that can also be frozen solid.
| flir wrote:
| > It may convey a certain life extension benefit.
|
| I think it would be more interesting if it _doesn 't_ affect
| lifespan. It would be a really counter-intuitive result (to
| me).
| metalman wrote:
| either way, or any info that could be gathered about life
| expectancy due to cryosuspension hibernation, is good, even a
| null result is data that plays into many conversations about
| longevity, space travel, temporary medical suspension to buy
| time. The fact of this type of biological process, moves the
| brackets quite a bit in how to think about many? all? other
| biological processes. Here is a little game....try and think
| about the world from a wood frogs perspective
| killjoywashere wrote:
| Evolutionarily, amphibians are somewhat simpler than mammals,
| they're smaller than a lot of mammals and they don't live as
| long, so I suspect some of this is simply that "things that
| aren't there". They wouldn't have as many problems with advanced
| glycation end products because the temperature is so low. There's
| at least one other ice survival strategy: antifreeze proteins.
| The fir tree and a variety of arctic fish have these:
| https://pmc.ncbi.nlm.nih.gov/articles/PMC6691018/.
|
| In all cases, I still don't understand how the membrane
| potentials are maintained or re-constructed in the thawing phase:
| any pointers?
| monkeycantype wrote:
| Perhaps because ice forms outside cells, freezing ions in
| place. Even if there was a very small area around ion channels
| that was liquid that equalized all ion concentrations with the
| cell, when the extra cellular fluid thaws the original
| concentrations would be pretty much restored
| danwills wrote:
| I think there are threads in Michael Levin's work that suggest
| membrane voltage potential may be able to be 'encoded' to
| microtubule structures and converted back into voltage
| potentials later. I don't think it's firmly established or
| understood yet but seems like a promising area for research!
| pkoird wrote:
| Curious to how long the frozen structure can "survive". I wonder
| if it's a good idea to freeze one such frog and thaw it centuries
| later (an amphibian time-traveler!)
| olejorgenb wrote:
| - Artificial experiment [1]: no longer than 3 months (but see
| disclaimer)
|
| - New study [2]: 7 months (with 100% survival rate)
|
| So further study seems to be needed.
|
| [1]
| https://journals.biologists.com/jeb/article/216/18/3461/1160...
|
| [2]
| https://journals.biologists.com/jeb/article/217/12/2193/1211...
| crazygringo wrote:
| If kept in pristine conditions (perfectly sealed to prevent
| evaporation leading to dehydration, deep freeze), is there a
| particular chemical needed for life that we might expect to
| break down first?
|
| Since chemical reactions happen in the freezer just slower...
| Qem wrote:
| > Since chemical reactions happen in the freezer just
| slower.
|
| Can't the gross just be kept at artificially lie
| temperatures to lengthen the stasis time? Say, -100C or
| even lower?
| Qem wrote:
| *the frog
| maronato wrote:
| The article says their cells don't freeze during
| hibernation. -100C would probably freeze the cells and
| kill them
| muzani wrote:
| It's a bit of a fantasy that we might find a perfectly well
| preserved dinosaur in a glacier somewhere.
| t-3 wrote:
| Not possible - the oldest ice we've found on the planet is
| much less than 10 million years old. Even if some area
| remained frozen long enough to contain an intact dinosaur, it
| would be buried deeply enough and under enough pressure to
| just be a bit more arctic oil by now.
| 8n4vidtmkvmk wrote:
| What about amber? Don't tell me that's a lie too
| ComputerGuru wrote:
| Forget the dinosaurs, we can't even preserve the glaciers
| themselves these days!
| megiddo wrote:
| Not one photo of said frog.
|
| Look, new rule: you write an article about frogs, you include a
| photo.
| jjcm wrote:
| here's an illustration of one:
| https://image.non.io/e9078e7d-5eb4-4787-9fe2-d7068d01a4df.we...
| daredoes wrote:
| this was really helpful! thanks!
| sgt wrote:
| But the article explains perfectly how they look like. White
| eyes, glucose filled cells, frozen solid as a rock. Bang it
| against a table, it's definitely frozen. Throw it back
| underneath those leaves.
| speerer wrote:
| Like the Tree Octopus?
| soco wrote:
| I really expected a wood(en) frog here, qualifying truly as a
| biological miracle. But the wood frogs are cool as well.
| furyofantares wrote:
| Oh god. This made me wonder, what _is_ wood, anyway? And I 've
| just come away much more confused.
|
| Bamboo is a grass and doesn't come from a tree. Palm wood comes
| from palm trees, except palm tree trunks are apparently a
| totally different type of structure than other tree trunks,
| sounds closer to Papyrus. No growth rings, a fiber type
| structure. Is Papyrus wood?
|
| Any plant matter above a certain density? I don't think that's
| it. Corn stalks aren't wood.
|
| Man, I don't know. I am certain that it must be plant matter
| though, so yes, a wooden frog would be a biological miracle.
| yial wrote:
| Wood is secondary xylem produced by growth from the vascular
| Cambium. (Sometimes? I think the issue is that there's more
| than one definition of wood depending on context ...?).
| Growth rings?
|
| But palm trees aren't truly trees, right ? Just called
| trees.... They're more of a tree like shrub? I think.
| furyofantares wrote:
| Trying to learn about this through claude was kinda funny.
|
| Ask it to tell me about wood that doesn't come from trees,
| and it tells me about palm wood. I say, but doesn't that
| come from palm trees? It says palm trees aren't technically
| trees because their trunk isn't wooden.
|
| Anyway, with your definition palm wood wouldn't be wood,
| and neither would bamboo. Feels like the vegetable/fruit
| thing though, there just isn't a perfect answer.
| mawise wrote:
| It's worse than that. _Tree_ isn't even a well-defined thing.
|
| > Trees are not a monophyletic taxonomic group but consist of
| a wide variety of plant species that have independently
| evolved a trunk and branches as a way to tower above other
| plants to compete for sunlight.[1]
|
| [1]: https://en.wikipedia.org/wiki/Tree
| mkl wrote:
| I don't know a precise definition, but wood has many origins.
| Wood has evolved hundreds of separate times, including at
| least 38 separate times just on the Canary Islands. https://w
| ww.researchgate.net/publication/341287935_Multiple_..., https
| ://www.pnas.org/doi/pdf/10.1073/pnas.2208629119?downloa...
| RajT88 wrote:
| What's really going to bake your noodle later is that Corn is
| a grass, just like Bamboo.
|
| My total armchair answer: It helps to think about trees as
| just giant shrubs.
|
| Shrubs are considered "woody", but most definitely are not
| trees. There are plenty of trees which are close relatives of
| shrubs (like poison oak and the urushi tree).
|
| So what's the difference between a grass and a tree? Walking
| the tree of life up from Poison Oak and Bamboo, we see we
| land at Monocotyledon and Eudicots. There's lots of non-woody
| and tough fibrous (i.e. woody) plans in both clades (palm
| trees are monocots, btw).
|
| Wikipedia says if it is tough and fibrous and has growth
| rings it's wood:
|
| https://en.wikipedia.org/wiki/Wood
|
| So Bamboo, although coming from a grass and not a tree, is
| wood. Further reading down that page talks about density as a
| key quality of wood, and goes on to _not definitively quality
| bamboo as wood or as non-wood_ but some are dense enough.
|
| Ultimately, there's no super clean definition of wood is my
| take-away, between the technical and colloquial aspects. You
| can use bamboo in construction much like wood, if you cut off
| a bit of shrub and dry it out, it's a "stick" just as much as
| if you trimmed it off a tree. You can make paper out of all
| kinds of fibers.
| NoImmatureAdHom wrote:
| It's best to think of it as "tree-ing" or "to tree"
|
| A really, really fantastic article:
| https://eukaryotewritesblog.com/2021/05/02/theres-no-such-
| th...
| the_arun wrote:
| Nicely written article. A few pictures could have made it more
| interesting.
| epicureanideal wrote:
| Someone tell Alcor about this.
| dexwiz wrote:
| Wood frogs only live 3-5 years, so they probably only go through
| a max of 5 of these cycles. I wonder how much cellular damage
| they accumulate during these cycles that they can tolerate due to
| short lifespans. They also have ~10,000x less neurons than a
| mammal.
|
| Even if you had the biochemistry that was able to do this, how
| many cycles could a higher life form tolerate this, assuming it
| would even work? Complex life seems to sacrifice some resiliency,
| such as the ability to regrow limbs. Amphibians already seem to
| be particularly adept at regeneration.
| e44858 wrote:
| "frogs don't freeze once and stay frozen. Instead, they spend a
| week or two freezing at night and thawing during the day until
| the temperatures drop permanently below freezing"
|
| https://shakerlakes.org/frozen-frogs/
| MPSimmons wrote:
| like maple syrup...
| kortilla wrote:
| Or water... or anything else with a freezing point that the
| ambient temperature crosses at night
| MPSimmons wrote:
| Oh sorry, I more meant specific to the times when you
| harvest maple syrup.
|
| If you didn't know, you need to wait to harvest maple
| syrup until you have a series of days when the daytime
| temperature is above freezing and the nighttime
| temperature is below freezing. This causes the maple sap
| to flow and allows it to collect in the bucket.
|
| https://botanistinthekitchen.blog/2013/03/18/maple-syrup-
| mec...
| 8n4vidtmkvmk wrote:
| I don't understand why we're not allowed to regrow limbs. What
| did that make room for in our DNA?
| macrolime wrote:
| Some animals regenerate, some form scar tissue. It's thought
| that scar tissue is a cheaper and faster mechanism than
| regrowing limbs and has thus been selected in many cases.
| 8n4vidtmkvmk wrote:
| If an iguana loses its tail, it doesn't just bleed until
| the new tail starts forming, right? Doesn't it seal up _and
| then_ regrow?
| tim333 wrote:
| The only animal that really does it properly is the
| salamander and I guess our family trees diverged before they
| figured that out?
|
| Still scientists are working on it - they've done frogs
| https://www.nbcnews.com/science/science-news/can-humans-
| regr...
| 8n4vidtmkvmk wrote:
| Can't just be the salamander. I saw an iguana regrowing its
| tale just last week. Geckos too. Pretty sure starfish as
| well.
| croisillon wrote:
| reminds me of the New Avengers episode "the eagle's nest"
| https://www.imdb.com/title/tt0659325/
| redundantly wrote:
| > ...the wood frog's liver produces large amounts of glucose that
| flushes into every cell in its body. This syrupy sugar solution
| prevents the cells from freezing...
|
| All natural, no preservatives added, sweetened frog popsicles!
| Yummy!
| crazygringo wrote:
| I'm not even joking about this -- since frog legs are a thing
| people eat (taste kinda like chicken), I'm now incredibly
| curious what this would taste like if you "caught" these in
| their frozen state and cooked them.
|
| Are we taking syrupy sweet meat? Or just a hint of it?
| lIl-IIIl wrote:
| According to the video in https://shakerlakes.org/frozen-
| frogs, it's also full of urine. Not sure if any left after
| the cooking process.
| olddustytrail wrote:
| Ok, this is what you really wanted:
| https://www.bbc.co.uk/programmes/p091w1b3
| sandgiant wrote:
| The content is not available in your location.
| olddustytrail wrote:
| Ah, sorry. I'll see if I can find an alternative source.
|
| Edit: I can't and I'm busy. Any UK folk who can provide this
| for our international family?
| imglorp wrote:
| Aquatic turtles have another brumination (hibernation) strategy.
| Since they breathe air, yet may get trapped under the ice for
| months at at time, they lower their metabolism plus have
| adaptations such as scavenging some oxygen from the water via
| rectal tissues as well as other chemical activity involving
| glucose and calcium.
|
| https://www.pbs.org/newshour/science/the-secret-to-turtle-hi...
|
| https://wildlifeinwinter.com/painted-turtle
|
| I have one at home in constant warm water, yet she can see the
| sky and decides to bruminate on her own: every year around this
| time, she starts napping in her under water hide for days or
| weeks at a time.
| card_zero wrote:
| That's a word I don't know (and neither do you): brumation,
| invented in 1965.
|
| https://en.wiktionary.org/wiki/brumation
|
| The verb ought to be _brumate._ But I guess the desire to pull
| it into line with _hibernation_ is strong, this happens with
| lots of words. (Or was the influence from "rumination"?)
| imglorp wrote:
| Oops, thank you.
| esperent wrote:
| Weirdly, I do know this word and I learned it exactly two
| days ago because I wanted to know the technical difference
| between Hibernation and Sleep in Windows 11.
|
| So I typed in "hibern..." to Kagi and it suggested
| "hibernation vs brumation". I got sniped because I'd never
| seen the word before. So yep, I did know. And probably would
| have forgotten by next week if I didn't see your comment! But
| now I'll remember forever, thank you.
| Loughla wrote:
| Our tortoise, even though he's in a very comfortable climate
| controlled indoor pen, tries to dig a hole every year to do the
| same.
|
| He's not very smart but he tries hard.
| zardo wrote:
| How are they thawing from the inside out?
| ledauphin wrote:
| this seems implausible to me based on how heat generally
| transfers...
| pcthrowaway wrote:
| Now I'm wondering all kinds of things about their brain. Are they
| capable of forming memories, and would they retain those memories
| after a freeze/thaw cycle?
|
| Effectively they're dead when they freeze. I'm assuming there's
| no brain activity.. Which means when they thaw they're being
| restored to life. I wonder if any other animals experience this
| card_zero wrote:
| Reading about them, it seems they migrate in winter (like half
| a mile uphill), but the adults always return to the same
| breeding pond in spring, so that information is stored
| somewhere.
| jon_richards wrote:
| I'm not surprised. There have been studies that show
| caterpillars retain memories through metamorphosis into a
| butterfly (a process that basically liquefies them).
| yyyfb wrote:
| Couldn't it just be algorithmic? Go uphill in the summer,
| then downhill until you hit water, you'll probably end in the
| same pond?
| userbinator wrote:
| Hibernate and resume.
| bobbylarrybobby wrote:
| I would assume that just as a computer's storage remains intact
| after a restart, these frogs' brains have internal structure,
| synaptic connections etc that are preserved after a freeze/thaw
| cycle.
| kortilla wrote:
| That's a bad assumption though. Based on our inability to
| bring brains back to life it seems very likely the better
| comparison is volatile memory like RAM.
| MacsHeadroom wrote:
| As discussed elsewhere in this thread, butterflies retain
| some memories formed as caterpillars after every cell in
| their body changes drastically. They never die but they
| change immensely and still retain memories, so I'm not sure
| we know enough to say what good and bad assumptions are
| here.
|
| Also this should be relatively trivial to test.
| gus_massa wrote:
| The nervous system of caterpillars is not disolved during
| the transformation.
| mathh wrote:
| Could such a mechanism be used for interstellar travel ?
| vitiral wrote:
| Of the frogs? Sure!
| 8n4vidtmkvmk wrote:
| No. Article says they have 1000x sugar in their blood. When we
| get to 10x we tend to die.
| ImHereToVote wrote:
| We could replace some of the Glucose with Xylitol. Xylitol is
| another sugar that protects the body from Advanced Glycation
| End Products. AGEs are what makes glucose so dangerous.
|
| https://www.healthline.com/nutrition/advanced-glycation-
| end-...
| RedNifre wrote:
| Be careful though, if you send an all female human crew
| enhanced by frog genes, some of them might change sex on the
| way.
| tantalor wrote:
| > wood frogs spend the winter frozen
|
| > syrupy sugar solution prevents the cells from freezing
|
| So they don't freeze. This is click bait.
| GavinMcG wrote:
| Why does it only count if the cells themselves freeze? Also, am
| I still allowed to play freeze tag, or do we need to rename
| that?
| vitiral wrote:
| Can't tell if joking...
| durkie wrote:
| A great book about how animals survive super cold winters is
| "Winter World" by Bernd Heinrich.
|
| Bernd is a super fascinating biologist who really dives deep in
| to things. At one point in the book I think he was talking about
| chipmunks surviving winter, and it goes really fun on the first
| principles. Something like: "chipmunks have a surface area of X
| m^2, and need to maintain an internal temperature of Y@C. If the
| outside temperature is -40@C they therefore they need to consume
| Z calories per hour just to maintain body temperature. Their
| favorite food are pine nuts from the white pine tree. The pine
| nuts each have B calories, so the chipmunk will need to eat D of
| them per hour. How many nuts can a chipmunk fit in its mouth?
| Well I found a dead one and shoved pine nuts in to its mouth
| until I couldn't fit anymore, and managed to get 17 in there.
| That means..."
| lukan wrote:
| "Well I found a dead one and shoved pine nuts in to its mouth
| until I couldn't fit anymore, and managed to get 17 in there."
|
| That part is .. weird. What is the point except morbid humor?
|
| Chipmunks have a food storage, so they don't store nuts in
| their mouth. They wake up, go to the food storage and eat and
| go back to sleep. They don't go outside to collect more nuts in
| -40degC. Maybe that was the point of that calculation, to show
| it would not be a good strategy, but there ain't much nuts in
| winter on trees left anyway.
|
| (and the calculation above lacks insulation of the fur and
| their sleeping place)
| speerer wrote:
| > What is the point except morbid humor?
|
| It'll be part of the time-spent-eating calculation, I expect.
|
| Edit: I think I found the direct quote among a trio from a
| Goodreads review, which gives more context [0]:
|
| > To get a rough idea of whether the flying squirrel's nest
| indeed affords much insulation, I heated a potato to simulate
| the body of a squirrel and examined its cooling rates.
|
| > I do not know how many seeds a chipmunk usually packs into
| each of its two pouches--I easily inserted sixty black
| sunflower seeds through the mouth into just one pouch of a
| roadkill.
|
| > Some years ago, I took on the brave, or foolish, task of
| measuring hornets' body temperatures, grabbing and stabbing
| them with an electronic thermometer as they left their nests.
|
| [0] https://www.goodreads.com/book/show/19954417
| jounker wrote:
| The number of seeds that fit into a cheek pouch determines
| calories transferred per trip to storage.
|
| Knowing this number will be critical for any modelling of
| chipmunk energetics.
| lukan wrote:
| They can also eat at the storage. Also some chipmunks have
| their food storage next to their bed.
|
| So knowing how big the cheeks are, is a useful information,
| but in this context not clear.
| abound wrote:
| > Nobody yet understands what starts the wood frog's heart after
| being frozen and inert for the entire northern winter.
|
| To me, that's the most fascinating part of the (already quite
| fascinating) story. Frog is frozen solid, there is no (to our
| knowledge) heartbeat or brain activity. It thaws and _something
| happens_ that gets it going again.
|
| I have trouble imagining what that mechanism could even look
| like. Tiny portion of brain responsible for keeping track of
| frozen-ness? Some chemical signaling from within the body cavity?
| chii wrote:
| a chemical reaction that is sensitive to temperature.
| telgareith wrote:
| my poor knowledge of biology says it's a deeply unsatisfying
| "heart beats when enough of the body has thawed for it to
| beat."
|
| If the heart depends on the brain at all in frogs.
| nine_k wrote:
| It doesn't, even in humans. There is an independent circuit
| of special muscle cells right on it that keeps it beating.
|
| So starting and stopping the heart in a controlled manner is
| pretty interesting, because it has to be well-timed, and
| there are few obvious and reliable inputs to control it,
| especially when thawing.
| 8n4vidtmkvmk wrote:
| Why doesn't my heart keep beating if my brain dies then? Or
| would it?
| kampsun wrote:
| I understand that it would keep beating until you are
| provided oxygen. That's my understanding understanding of
| brain death at least.
| oharapj wrote:
| Probably because the brain controls breathing and so the
| oxygen runs out quickly
| 8n4vidtmkvmk wrote:
| I was going to say that's silly, but I guess we need to
| be able to hold our breath sometimes.
| telgareith wrote:
| "Even in humans"- thats a pretty steep assumption.
|
| I am fully aware that if the human heart is severed from
| the brainstem it will develop _A_ rhythm.
|
| But what about other mammals? Dunno. Not going to assume.
|
| Theres also the tidbit that frogs are not mammals.
| nine_k wrote:
| The point is that whatever control a frog heart may have,
| it's not cerebral. It must be a very low-level circuit,
| which can be modulated from outside, but which remains
| autonomous.
| LoveMortuus wrote:
| Maybe something like a bit flip but for neurons happens in the
| frog's brain from the sun's radiation or something.
|
| Or the elasticity of the heart and muscles.
| necovek wrote:
| If it gets frozen in a heavily contracted form, unthawing it
| will trigger at least one half-beat: could that be enough to
| restart it?
| gnatolf wrote:
| Hard to imagine that this is significant, given that the
| (un)thawing is likely quite slow.
|
| Did not think that my early morning would be spend trying
| to imagine how thawing a frog works. :)
| necovek wrote:
| Good point for sure.
| PittleyDunkin wrote:
| The frog is _not_ frozen solid.
| PhasmaFelis wrote:
| Interestingly, you can freeze a rat solid in liquid nitrogen
| --completely solid right through--and then thaw them out in a
| microwave and they actually survive. Well, many of them
| survive. For a while. Okay, it's not good for the rats but
| it's still crazy that it works.
| plastic3169 wrote:
| Where can I read more about this? If this was a fact I
| think people would be way more excited about cryonics.
| Casually browsing wikipedia suggests that we are not there
| yet with the ability to thawn large animals or even organs.
| terribleperson wrote:
| I can't source this because I read it years ago, but I
| _believe_ that there is some science that says that a
| major factor (not the only major factor, but a major
| factor) is body mass and volume. Essentially, the speed
| at which the core organs go from operating temperature to
| frozen is crucial, and it 's also important for them to
| be deprived of oxygen when that happens. Humans are
| just... too big.
| sriacha wrote:
| There are ways to adjust cooling rates... for example
| route the blood externally and chill it like they do in
| some kinds of surgery.
| blue_pants wrote:
| From https://en.wikipedia.org/wiki/James_Lovelock
|
| "In the mid-1950s, Lovelock experimented with the
| cryopreservation of rodents, determining that hamsters
| could be frozen and revived successfully.[14] Hamsters
| were frozen with 60% of the water in the brain
| crystallised into ice with no adverse effects recorded.
| Other organs were shown to be susceptible to damage.[15]"
|
| And there's a Tom Scott's interview with James Lovelock:
|
| https://www.youtube.com/watch?v=2tdiKTSdE9Y
| mock-possum wrote:
| Wouldn't it be crazy if _only_ worked on hamsters
| tim333 wrote:
| I was checking youtube to see if I could see that happen
| but failed - they were all about thawing rats to feed to
| snakes. There was however a goldfish dropped in liquid
| nitrogen briefly and recovering
| https://www.youtube.com/watch?v=wwolYFGM9pU
| m463 wrote:
| What puzzles me is... it is not just the heart but the entire
| circulatory system.
|
| Maybe it is that thawing happens in reverse with the
| extremities, then the rest of the system thawing, with the
| heart being last. Would be a biological advantage in this case
| for the heart to be centrally located.
| Someone wrote:
| > Maybe it is that thawing happens in reverse with the
| extremities, then the rest of the system thawing, with the
| heart being last
|
| FTA: In spring, the wood frog thaws from the inside outward.
| First the heart starts beating. Then the brain activates.
| Finally, the legs move.
| cmrx64 wrote:
| The article says that, but it can't be the normal meaning
| of thaw. Thermodynamically, onbiously the innermost portion
| of the volume is going to warm last. But in terms of the
| frog's system restart order, that order makes sense.
| ethbr1 wrote:
| The inside of the frog isn't actually frozen, because
| it's glucose-flushed.
|
| So the sequence is more: 1. Outside of
| frog thaws 2. ?? 3. Heart starts beating
| Someone wrote:
| This frog is alive. It could detect that long-term thaw
| is imminent (say from sensors on its skin) and start some
| processes that produce heat around its heart.
| abainbridge wrote:
| I skimmed
| https://en.wikipedia.org/wiki/Sinoatrial_node#Function. Here's
| my guess at what is going on:
|
| In humans (and I guess many animals), the thing that controls
| the heart beat is a structure in the heart called the
| Sinoatrial node. Each cell in the SA node has an ability to
| generate its own rhythmic electrical impulse. I imagine that
| when one of these cells thaws out in a Wood frog, it
| immediately starts producing its rhythmic pulse. It has to get
| in sync with the rest of the cells in the Sinoatrial node
| before the heart will beat correctly, so the cells have a
| mechanism to communicate their rhythm with their neighbours. I
| guess each cycle, each cell adjusts its phase a little towards
| the average phase of its neighbours and thus a consensus will
| be reached.
| mock-possum wrote:
| Fireflies eventually manage to more or less sync up and
| they're completely separate organisms - tiny cells with
| physical connections inside the body should be able to make
| it work.
| agumonkey wrote:
| Maybe the system relies on average heat randomness to bootstrap
| again ..
| xg15 wrote:
| Yeah, I was wondering about that too, but on the other hand,
| there are possibilities:
|
| You don't need a brain to execute "programmed behavior" in a
| body, the cells have enough "compute" in the regulatory
| networks of their DNA, RNA and proteins to do that on their own
| (and in fact do it all the time as part if their normal
| functioning. That's what "metabolism" means.)
|
| Another question would be where the cells take the energy to
| execute that program if blood circulation has halted and there
| is no oxygen. But then on the other hand, at that point they
| are filled to the brim with glucose. So I wonder if this isn't
| just to prevent freezing but also as an energy reserve for the
| "restart".
|
| (Sorry for the bad programming analogies in this post, please
| don't take them too literally)
| sandworm101 wrote:
| Most likely it isnt that the heart stops or starts in response
| to freezing. The heartbeat signal probably runs 24/7 unless
| inhibited by freezing. So as soon as it thaws, the signaling
| bit resumes its pulsing and the rest of the heart begins to
| beats as it also thaws. The order in which organs thaw would be
| regulated by sugar levels. Remember too that at this scale
| frogs can absorb much of their needed O2 through their skin. A
| steady heartbeat isn't as essential as it is with us.
| LoveMortuus wrote:
| I hope the frogs don't feel pain... Imagine getting frozen alive
| and extremely slowly.
| ssr2020 wrote:
| The One who created it with care and compassion has arranged
| its pain. Perhaps it is like us waking up from sleep."
| m463 wrote:
| looking at wikipedia, there is more information:
|
| > Frogs can survive many freeze/thaw events during winter if no
| more than about 65% of the total body water freezes
|
| https://en.wikipedia.org/wiki/Wood_frog#Cold_tolerance
| javajosh wrote:
| _> Also, the wood frog's ability to withstand freezing may help
| researchers discover how human organs used for transplants could
| be frozen and thawed without damage. This would increase the
| allowable time between removing an organ from a donor and
| implanting it within the recipient, which could make many more
| transplants possible._
|
| While certainly some good would come of this, imagine the
| unintented consequences of such an advancement, especially in a
| world with stark income inequality.
| w10-1 wrote:
| For those thinking freezing could be an option... there's a fair
| bit more than just avoiding ice crystals.
|
| Medical hypothermia in humans (which is just a few degrees
| colder) is bounded not really by not by time-cold but by
| restoring normal temperature too quickly. It turns out
| mitochondria generate a lot of free oxygen radicals when going
| hypoxic, and restoring oxygen quickly does the chemical damage
| that actually causes death - so they restore normal temps over a
| period of hours. I'd bet that's not the only metabolic cycle
| deranged by hypercooling.
| ImHereToVote wrote:
| Couldn't you inject liposomal ATP into the bloodstream before
| the cooling process? Then mitochondria could simply be turned
| off. (I don't mean simple when I use the word simply)
| rendall wrote:
| > _Understanding how frogs can do this might provide valuable
| knowledge to help in the management of high blood sugar in people
| with diabetes._
|
| Also, space travel!
| tim333 wrote:
| One min video with some frozen frogs https://youtu.be/SSvspDZOVV0
|
| They only seem part frozen - still a bit bendy when touched.
| wkjagt wrote:
| > No heartbeat. No breathing. For the entire winter, the wood
| frog is like a lump of hard, frigid, icy stone carved in the
| shape of a frog. But it's alive, in a state of suspended
| animation.
|
| I find it hard to grasp what is still alive about the frog. I
| mean, it's not dead so there must be something happening inside
| the frozen frog? How does it compare to a dead (and frozen) wood
| frog?
| fhfjfk wrote:
| A live frozen frog has ice around it's cells. Inside the cells
| remains liquid because of extra glucose acting as anti-freeze.
|
| A dead frozen frog will be frozen completely, with all the
| cells having ruptured walls from their insides freezing.
___________________________________________________________________
(page generated 2024-11-16 23:01 UTC)