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looked into the subject last and I may be out of date.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 

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 
 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 
 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 
 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 

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,


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.

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