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Biological Miracle – Wood Frog

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Re: Biological Miracle – Wood Frog

#101

Post by mock-possum »

blue_pants wrote: post #92
plastic3169 wrote: post #82

Earlier quoted context omitted.

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.

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 Lo…

Wouldn’t it be crazy if only worked on hamsters

Re: Biological Miracle – Wood Frog

#103

Post by xg15 »

abound wrote: post #66

> 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…

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)

Re: Biological Miracle – Wood Frog

#104

Post by cmrx64 »

Someone wrote: post #90
m463 wrote: post #79

Earlier quoted context omitted.

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.

> 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.

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.

Re: Biological Miracle – Wood Frog

#106

Post by tim333 »

plastic3169 wrote: post #82
PhasmaFelis wrote: post #72

Earlier quoted context omitted.

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.

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.

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

Re: Biological Miracle – Wood Frog

#107

Post by sandworm101 »

abound wrote: post #66

> 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…

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.

Re: Biological Miracle – Wood Frog

#108

Post by gus_massa »

MacsHeadroom wrote: post #65
kortilla wrote: post #64

Earlier quoted context omitted.

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.

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.

The nervous system of caterpillars is not disolved during the transformation.

Re: Biological Miracle – Wood Frog

#109

Post by tim333 »

8n4vidtmkvmk wrote: post #85
dexwiz wrote: post #17

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 s…

I don't understand why we're not allowed to regrow limbs. What did that make room for in our DNA?

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...

Re: Biological Miracle – Wood Frog

#110

Post by speerer »

lukan wrote: post #99
durkie wrote: post #62

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 out…

"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 -40°C. Maybe that was the point of that calculat…

> 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

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