X-Message-Number: 14876 From: "Marta Sandberg" <> Subject: Frogs and fish Date: Wed, 08 Nov 2000 08:15:15 GMT In the last weeks there have been postings about frozen frogs and their relevance to cryonics. I have waited with my reply as I hoped someone else would post a comprehensive reply. I know a bit about it, but unfortunately it was several years since I really looked into the subject last and I may be out of date. But I'll try none the less. Lets start with my final conclusion. Studies of animals who naturally have cryoprotection give us some interesting pointers and may one day become relevant to practical cryonics. Some species of insects, frogs, snakes (and possible squirrels) can apparently freeze without harmful effects. Of those animals it is squirrels that excite me most, as they are warm-blooded. Unfortunately, they are also the least studied animals. It appears that these animals either have cells that can survive freezing without harm (eg some insects) or they produce glycerol in their bodies that prevent ice formation as they freeze (eg frogs). All of this sounds very promising, but there are problems with trying to apply these findings to cryonics patients; h The animals can only stay frozen or in suspended animation for a few months. h There is no evidence that they are totally frozen, in fact it is likely that at least part of the brain is not 'frozen solid'. h They cannot tolerate very low temperatures or freezing damage will occur anyway. h They all appear to have inbuilt adaptations to make them tolerant to their ordeal (eg cells that can take partial dehydration or high levels of glycerol concentration). h We don't know that their minds survive the freezing process. As one researcher said to me "I don't know. How do you tell if a frog is brain damaged?" (private correspondence). I find Antarctic fish a much more promising avenue of research. They are sometimes overlooked by cryonicsits, as these fish don't freeze. That's the whole point. They should. They live in waters that are so cold that their flesh should become at least partially frozen in winter, yet their cells contain natural antifreeze that appears to inhibit ice formation or breaks up the ice crystals as soon as they are formed. Some of those compounds have been isolated and their structure determined. All of them are huge, complex molecules. Just by looking at them it is not apparent how they work. Pity. Different fish species have different antifreeze molecules. Very, very different molecules. This is both puzzling and promising. There are two ways to interpret this wide diversity of anti-freeze molecules. EITHER there are many ways in which ice formation can be blocked and each species have evolved along its own separate path, OR the anti-freeze molecules are mainly 'inert bulk' with small active sites that do the actual work. It may seem strange that fishes should evolve large molecules that are chiefly wasted bulk, but it makes perfect sense from the fish point of view. These fish live in a harsh environment where resources are scarce. They need antifreeze; it is produced in their own cells and use up some of these scarce resources. If the cells keeps on losing their freeze protectants they have to continuously produce more. It's a much better solution to make the molecules so large that they can't escape through the cell membrane. Hence, large molecules with small active sites. If this is true then it is possible to find these sites (just as it is possible to find a needle in a haystack). As the structure of more natural anti-freeze molecules are determined the task becomes easier. You can compare the molecules and look for similar structures hidden amongst their mass. Then we may be left with a small molecule that can easily slip in and out of cells and is ferociously effective in preventing ice formation. Very good news for cryonics, if and when this theoretical mini-anti-freeze molecule is developed... On the other hand, maybe the whole molecule is needed to do its job. Then each fish must use a different tactic to disrupt ice formation (or maybe break down ice crystals as soon as they are formed). Even that can be good news for cryonics as it can points the way to a choice of different methods for preventing ice damage. At least one of those could be useful to us. Before we get too optimistic I should point out some of the problems with Antarctic fish. h The fish only live in Antarctica, this makes them expensive and difficult to study. h The fish are all protected species, and that adds extra problems when studying them. h The fish stinks! This makes the research and researchers unpopular subjects. (The Antarctic research hut is placed as far from the main camp as it can be, and the researchers often have a whole table for themself in the dining room.) h There are very limited supplies of the antifreeze compound available and it is prohibitively expensive. Some can be synthesised, but it is difficult to produce such complex molecules. h The last point is moot. The molecules are too large to be absorbed into cells. Unless they can be slimmed down they can't be used as a perfusate anyway. h It s possible that when we do unravel the secrets these fish use, it uses some pathway that is impossible for cryonicists to imitate But the research that is being done is already of interest to cryonics as it looks at what actually happens when ice is formed in an impure environment (such as the inside of a cell). When they explained it in high school physics it all seemed so simple - when water molecules become cold enough they stick together and ice crystals grow like an endless jigsaw puzzle. The reality is different. I remember viewing an animated computer simulation of the water/ice boundary seen at a molecular level. I was fascinated. Ice isn't a stable thing. At the edge new water molecules are constantly captured and others break free. Even those that are captured form a helter-skelter pattern where each molecule jostles for position with its neighbours and only slowly becomes recognisable ice crystal structure. You can t really say where the water end and the crystal begin; they flow into each other in a nervous, complex dance. Even inside the proper ice crystal, each molecule still vibrates and occasionally it jumps out of place and creates a mini-crack in the ice. These can grow until a whole shard of ice breaks free. Or they can heal and close again. Always movement, never still. This is very good news for cryonics. A process this dynamic must be amenable to manipulation. Once we learn how. The research is forging onwards. And unlike a lot of esoteric research, their funding seems reasonable secure. Let me finish with a small (improbable) story of how airplanes can help cryonics. A lot of people who buy airline tickets live in cold climates. Airplanes need airports to land on. In winter the runways may ice up and then the airplanes can't use them. Large airports can afford expensive mechanical systems to keep their runways ice-free, but smaller airports have to rely on chemical compounds that inhibit ice formation. These compounds wash off the runways into the watertable and pollute it. There are laws about pollution. At the moment the airports are breaching the environmental guidelines and have to get exemptions to continue operating. These exemptions are getting harder and harder to get and fairly soon the airports must find another, environmentally-friendly way to keep the ice off their runways. Unlike their runways, Antarctic fish don't freeze. Guess who finds this an exciting fact? Guess who is major sponsors for Antarctic fish research? Isn't it nice when the rest of the world seems to conspire to help cryonics. Thanks to airport and Antarctic fish we may one day have the perfect ice-inhibiting perfusate. That's a good thought to end on. Log life, Marta PS In the beginning of my message I explained that my information may be out of date and incomplete. If anyone can update this posting or correct any mistakes I have made I would be grateful. Thank you. _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. 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