WEBVTT

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Have you ever wondered how fish survive in freezing

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Arctic oceans, or how an Alaskan beetle withstands

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negative 30 degrees? In this episode of The Deep

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Dive, we unpack the miraculous world of antifreeze

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proteins, AFPs, and ice -structuring proteins,

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ISPs. We explore the evolutionary heists, the

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quantum -level physics of thermal hysteresis,

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and the mind -bending biology that prevents living

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cells from turning into solid ice. Plus, discover

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how these same biological cheat codes are sitting

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in your kitchen freezer right now, and how they

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might just be the key to human cryopreservation

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and space exploration. Tune in for a fascinating

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journey through extreme survival, convergent

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evolution, and the future of cryobiology. Have

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you ever left a glass bottle of water in the

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freezer and just completely forgotten about it?

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Oh, definitely. Right. And you come back a few

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hours later, maybe the next morning, and you

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open the freezer door to an absolute disaster.

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It's just shattered glass everywhere. Everywhere.

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The water inside froze, it expanded, and it just

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violently destroyed its container. Because water

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expands when it turns to ice. It's just a fundamental

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rule of nature. Exactly. Now... I want you to

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take that exact same scenario, but I want you

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to shrink it down to the microscopic level. you

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know, jagged expanding ice crystals forming not

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inside a rigid glass bottle, but inside the incredibly

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delicate microscopic cells of a living organism.

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That sounds like a nightmare. It really is. By

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all the laws of biology, physics, and chemistry,

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it should be an absolute death sentence. The

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physical expansion alone would just rupture the

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cell membranes, shred the internal organelles,

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systematically destroy the tissue from the inside

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out. It should be game over. Yeah. And yet, if

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you look at our planet life... is incredibly

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almost absurdly stubborn. It really is. I mean

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life absolutely thrives in the freezing, lightless

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oceans of Antarctica. It thrives beneath miles

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of pack ice in the Arctic and it survives the

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bitter sub -zero winters of the Northern Hemisphere.

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It's a fundamental biological paradox. It's puzzled

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scientists for generations, honestly. Because

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they should just freeze. Exactly. We are talking

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about environments where the ambient temperature

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drops well below the freezing point of water.

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And since living things, from a microscopic algae

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to a massive fish, are largely made of water.

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They're essentially just big bags of water. Right.

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So they should theoretically freeze solid the

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moment the temperature dips. Their blood should

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turn to slush. Their cells should crystallize.

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But they don't. And the way they avoid this seemingly

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inevitable biological fate is nothing short of

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an evolutionary miracle. And that brings us to

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the mission for today's deep dive. We are going

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to discover the biological cheat codes that allow

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life to survive the deep freeze. I like that.

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Cheat codes. It really feels like they are hacking

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the system. Our source material for this exploration

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is a really comprehensive look into a miraculous

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class of molecules known as anti -freeze proteins.

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Or AFPs, for short. Yes, AFPs. Though, as you'll

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find out a bit later today, if you look at a

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food label, they are sometimes more commercially

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known as ice -structuring proteins. Which is

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a brilliant rebrand. It is. Okay, let's unpack

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this. Because when I first started reading through

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these sources, I thought, uh, I thought this

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was just about a few weird fish. But how big

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is the scope of this phenomenon, really? The

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scope is massive. And frankly, it spans the entire

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tree of life. Wow. In this deep dive, we are

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going to explore the literal physics of freezing

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and how these incredibly specialized proteins

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hack those physics. We'll look at the wild evolutionary

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leaps that created them too. Exactly. Sometimes

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seemingly out of nowhere or through methods that

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defy our traditional understanding of genetics,

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we will examine the surprising and frankly beautiful

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diversity of these molecules across fish, insects,

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plants, fungi, and microbes. It's everywhere.

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And finally, we will look at how these very same

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proteins have made the leap from the freezing

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Arctic oceans into commercial everyday applications.

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Which is my favorite part. There is a very good

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chance that some of the mechanisms we discussed

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today are sitting right inside your kitchen freezer

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right now. I absolutely love that. It takes something

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so alien and just brings it right into your home.

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So I want to start by redefining what we mean

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by the word antifreeze. That's a good place to

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start. Because I think for you, me, and anyone

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listening, when you hear that word, your mind

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immediately goes to the garage. Right, car maintenance.

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You think of that brightly colored neon green

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or pink toxic liquid you pour into your car's

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radiator before the winter hits. Which is usually

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a chemical called ethylene glycol. And it works

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by what chemists call colligative properties.

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Which is the term that sounds a bit intimidating.

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It does. But it essentially means it works by

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sheer brute force volume. Right. I was reading

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that with car antifreeze, you literally have

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to pump a ton of it into the water to get the

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freezing point to drop. You're fundamentally

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changing the ratio of the liquid. It's like trying

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to stop a crowd from dancing by just shoving

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an equal number of people who refuse to dance

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into the room. That is a brilliant way to put

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it. It's a volume game. Just crowding the floor.

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And if we connect this to the bigger picture

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of a living, breathing organism, a brute force

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approach just isn't biologically viable. Because

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you can't just fill a fish with neon green chemicals.

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Exactly. You cannot simply pump a living fish

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full of a traditional solute like ethylene glycol.

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And even if it wasn't toxic, you couldn't pump

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them full of massive amounts of salt or sugar

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to lower their freezing point either. Because

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it would completely mess up their internal balance,

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right? I mean, fish already have to regulate

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their salt levels so carefully. Exactly. It would

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cause a massive fatal shift in osmotic pressure.

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Osmosis being the water balancing act. Right.

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Osmosis is the process that dictates that water

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always wants to balance out solute concentrations

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across a cell membrane. If a cell suddenly floods

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its interior with massive amounts of a solute,

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like sugar or salt, just to prevent freezing,

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the water outside the cell would rush in to dilute

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it. And the cell would swell up. And literally

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burst. Or, conversely, If the solute was heavily

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concentrated in the blood, it would draw all

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the water out of the surrounding tissues, completely

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dehydrating the animal from the inside out. So

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the animal would basically turn into a piece

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of biological beef jerky. Precisely. They would

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die of dehydration while surrounded by water.

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That is a terrible irony. So the absolute beauty

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of antifreeze proteins is that they work in a

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non -colligative manner. Meaning they don't rely

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on sheer volume at all. Not at all. I was floored

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by the numbers in our sources. They note that

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AFPs are effective at concentrations 1 300th

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to 1 500th of other dissolved solutes. It's a

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fraction of a fraction. If we go back to our

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room full of dancers, instead of flooding the

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room with non -dancers, the organism just sends

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in two or three highly trained bouncers to stand

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exactly where the dancing starts and shut it

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down. I like the bouncer analogy. It is a hyper

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precise biochemical surgical strike. They don't

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flood the system. They target the problem at

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incredibly low concentrations, which completely

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minimizes any dangerous effect on the organism's

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delicate osmotic pressure. execute that targeted

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strike is through a fascinating physical mechanism.

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They don't just float around randomly. They selectively

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seek out and bind to specific crystalline forms

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of ice the microsecond they begin to form. Just

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grabbing them. Essentially creating a physical

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blockade that stops the ice nucleation process

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dead in its tracks. And this leads us to a term

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in the source material that I absolutely have

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to geek out over. Oh, I know which one you mean.

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The term is thermal hysteresis. I'm not gonna

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lie, it sounds like an incredible sci -fi band

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name. It really does. But it is actually the

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core fundamental mechanism of how AFPs keep these

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creatures alive. It is a great term, and it is

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the key to everything we are talking about today.

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Hysteresis generally refers to a phenomenon where

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the state of a system depends on its history,

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or where there's a lag in a reaction. Okay. To

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break thermal hysteresis down for you in this

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context, it is effectively the artificial gap

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created between the melting point of water and

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the freezing point of water. Right, because normally

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those two things are the exact same temperature.

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Water freezes at zero degrees Celsius and ice

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melts at zero degrees Celsius. It's a two -way

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street at the exact same intersection. Exactly.

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Under normal thermodynamic laws, it's a perfectly

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balanced equilibrium. But when an organism possesses

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antifreeze proteins, it breaks that equilibrium.

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Those proteins physically wedge themselves at

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the microscopic interface between the solid ice

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crystal and the liquid water surrounding it.

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And by doing this, they kinetically inhibit the

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growth of the ice crystal. They push the freezing

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point down while the melting point remains exactly

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the same. I love the phrasing in the source material.

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It stops the thermodynamically favored growth.

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Yes. Physics says, I am at zero degrees, I want

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to freeze, I need to freeze. And the protein

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steps right in the middle of that chemical reaction

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and says, access denied. That is a perfect way

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to visualize it. The proteins literally cover

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the water -accessible surfaces of the microscopic

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ice crystals. They hold open this gap, this hysteresis.

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They create a state of tension where the water

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should be ice, but it is forced to remain liquid.

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And looking at the data from the sources, the

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maximum level of thermal hysteresis shown by

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fish AFPs is approximately negative 3 .5 degrees

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Celsius. Which is about 29 .3 degrees Fahrenheit.

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Now, when I first read that, I thought, wait,

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negative 3 .5 degrees? That doesn't sound like

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a massive drop. It doesn't sound like much. I

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was expecting them to push it down to negative

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50 or something. Yeah, sure. But then the material

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clarified why that is exactly, perfectly what

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they need. Right, because aquatic organisms are

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typically only exposed to water temperatures

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that drop to about negative 1 or negative 2 degrees

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Celsius below freezing. Because ocean water itself

00:10:10.600 --> 00:10:13.179
generally freezes around negative 1 .9 degrees

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Celsius. The salt content lowers the freezing

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point of the ocean itself. Exactly. So if the

00:10:18.879 --> 00:10:21.200
fish's blood is protected down to negative 3

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.5, that gives them an absolutely perfect, comfortable

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safety buffer. but there is a catch here, isn't

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there? It's not a flawless magic shield. This

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raises an important question about the limits

00:10:31.460 --> 00:10:33.539
of biology, and you are right to point it out.

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The catch is that the rate of cooling absolutely

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matters. These proteins are incredible marvels

00:10:40.679 --> 00:10:44.299
of engineering, but they are still physical molecules

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floating in a fluid. Many time to work. They

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require a little bit of time to physically find

00:10:48.759 --> 00:10:52.320
the nascent ice crystals. orient themselves and

00:10:52.320 --> 00:10:55.200
bind to them. So if there is a sudden rapid plunge

00:10:55.200 --> 00:10:57.759
in temperature? It can actually substantially

00:10:57.759 --> 00:11:00.500
decrease the thermal hysteresis value. Oh, wow.

00:11:00.720 --> 00:11:03.360
The freezing point drops so fast and the ice

00:11:03.360 --> 00:11:05.919
grows with such violent speed that the proteins

00:11:05.919 --> 00:11:08.460
simply cannot keep up. They are overwhelmed.

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Consequently, these organisms can still easily

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freeze to death if the temperature drops too

00:11:13.320 --> 00:11:15.820
abruptly. So they need the cold to arrive at

00:11:15.820 --> 00:11:19.340
a relatively natural gradual pace. Yes, so their

00:11:19.340 --> 00:11:22.360
internal defenses can mobilize and cap the ice

00:11:22.360 --> 00:11:25.240
crystals as they form. So it is this dynamic,

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high -stakes battle between the speed of the

00:11:27.519 --> 00:11:29.679
temperature drop and the physical reaction time

00:11:29.679 --> 00:11:32.279
of the proteins. It's a race. That is incredibly

00:11:32.279 --> 00:11:34.039
dramatic when you think about it happening inside

00:11:34.039 --> 00:11:37.149
the blood vessels of a tiny fish. and it perfectly

00:11:37.149 --> 00:11:38.909
sets up something else I found fascinating in

00:11:38.909 --> 00:11:42.009
the sources, which is... Not every organism uses

00:11:42.009 --> 00:11:44.850
these proteins the exact same way. The material

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outlines two very distinct survival camps. I'll

00:11:48.649 --> 00:11:51.470
admit, one makes total sense to me, and the other

00:11:51.470 --> 00:11:53.629
sounds completely insane. I think I know where

00:11:53.629 --> 00:11:55.690
you're going with this. Can you clarify the difference

00:11:55.690 --> 00:11:57.789
between the freeze -avoidant species and the

00:11:57.789 --> 00:12:00.990
freeze -tolerant species? Gladly. The first camp

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is the freeze -avoidant species, which is the

00:12:03.529 --> 00:12:05.759
one that... probably makes the most intuitive

00:12:05.759 --> 00:12:08.279
sense. Right. These are the organisms, like the

00:12:08.279 --> 00:12:11.399
fish we just discussed, that use AFPs to prevent

00:12:11.399 --> 00:12:14.100
their body fluids from freezing entirely. Their

00:12:14.100 --> 00:12:17.200
singular goal is zero internal ice. They hold

00:12:17.200 --> 00:12:19.740
the line, they use the proteins to create that

00:12:19.740 --> 00:12:22.240
thermal hysteresis gap, and as long as they stay

00:12:22.240 --> 00:12:24.679
within that temperature buffer they remain completely

00:12:24.679 --> 00:12:27.500
liquid. But as we just discussed with the cooling

00:12:27.500 --> 00:12:30.159
rates, if the temperature drops too low or too

00:12:30.159 --> 00:12:33.299
fast, the AFP function is overwhelmed, ice grows

00:12:33.299 --> 00:12:35.659
rapidly throughout their body fluids, and they

00:12:35.659 --> 00:12:38.779
die. Yes. For them, any significant internal

00:12:38.779 --> 00:12:41.120
freezing is fatal. It's an all -or -nothing defense

00:12:41.120 --> 00:12:44.259
mechanism. The shield either holds, or the organism

00:12:44.259 --> 00:12:47.340
perishes. But the second camp, the freeze -tolerant

00:12:47.340 --> 00:12:49.340
species. This is the one where my mind just gets

00:12:49.340 --> 00:12:52.840
blown. It is truly remarkable. Freeze -tolerant

00:12:52.840 --> 00:12:56.000
species actually survive the freezing of their

00:12:56.000 --> 00:12:57.919
internal body fluids. They don't just tolerate

00:12:57.919 --> 00:13:01.279
the cold. They tolerate turning into ice. For

00:13:01.279 --> 00:13:04.600
these organisms, the AFPs aren't trying to stop

00:13:04.600 --> 00:13:07.700
the freeze entirely. They aren't trying to maintain

00:13:07.700 --> 00:13:10.179
a purely liquid state. So what are they doing?

00:13:10.659 --> 00:13:13.620
Instead, they act as what we call cryoprotectants.

00:13:13.850 --> 00:13:16.490
Meaning, they manage the freezing process rather

00:13:16.490 --> 00:13:18.809
than preventing it? Exactly. But how does that

00:13:18.809 --> 00:13:20.889
not shred their cells like the glass bottle in

00:13:20.889 --> 00:13:23.250
the freezer? Because they inhibit something called

00:13:23.250 --> 00:13:26.330
recrystallization. Recrystallization? When ice

00:13:26.330 --> 00:13:29.169
first forms, it usually starts as lots of very

00:13:29.169 --> 00:13:32.590
tiny microscopic crystals. On their own, these

00:13:32.590 --> 00:13:35.149
tiny crystals aren't immediately lethal. Okay.

00:13:35.389 --> 00:13:38.450
But over time, thermodynamics pushes those tiny

00:13:38.450 --> 00:13:41.649
crystals to fuse together into larger, much more

00:13:41.649 --> 00:13:44.529
stable, and much more destructive ice crystals.

00:13:44.809 --> 00:13:46.750
The large crystals that act like microscopic

00:13:46.750 --> 00:13:49.090
knives, slicing through cell membranes and destroying

00:13:49.090 --> 00:13:53.090
tissue. Okay, so the AFPs in freeze -tolerant

00:13:53.090 --> 00:13:56.070
species, they bind to the tiny crystals and stop

00:13:56.070 --> 00:13:58.409
them from fusing together. Yes, they keep the

00:13:58.409 --> 00:14:01.490
ice small and manageable. This stabilizes the

00:14:01.490 --> 00:14:03.610
cell membranes and prevents the massive tissue

00:14:03.610 --> 00:14:06.590
damage. the deadly knives into harmless sand.

00:14:06.870 --> 00:14:09.190
That is exactly it. What's fascinating here is

00:14:09.190 --> 00:14:12.049
that to pull this off, these freeze -tolerant

00:14:12.049 --> 00:14:14.830
organisms often work in conjunction with another

00:14:14.830 --> 00:14:17.669
type of protein altogether. Called ice -nucleating

00:14:17.669 --> 00:14:20.870
proteins, or INPs. Yes. Now wait, I had to read

00:14:20.870 --> 00:14:23.029
this twice in the notes. They actually have a

00:14:23.029 --> 00:14:25.710
protein specifically dedicated to starting the

00:14:25.710 --> 00:14:27.669
freezing process. Why would they want to do that?

00:14:27.870 --> 00:14:30.330
It sounds counterintuitive, but it's a stroke

00:14:30.330 --> 00:14:33.580
of genius. The INPs intentionally trigger the

00:14:33.580 --> 00:14:36.259
freezing process at relatively high sub -zero

00:14:36.259 --> 00:14:39.159
temperatures. Oh. Because if they control when

00:14:39.159 --> 00:14:41.379
it freezes, they control how it freezes. Exactly.

00:14:41.460 --> 00:14:44.000
They take control of the environment. By initiating

00:14:44.000 --> 00:14:46.960
the freeze early and predictably, it allows the

00:14:46.960 --> 00:14:49.179
organism to control the rate of ice propagation.

00:14:49.379 --> 00:14:53.490
It's a slow... managed rollout of ice. The INPs

00:14:53.490 --> 00:14:55.970
start the fire, so to speak, in a controlled

00:14:55.970 --> 00:14:59.190
manner, while the AFPs ensure the resulting iced

00:14:59.190 --> 00:15:01.610
crystals stay incredibly small and harmless.

00:15:02.009 --> 00:15:05.879
It is a highly choreographed biologically controlled

00:15:05.879 --> 00:15:09.840
freeze that allows the organism to survive being

00:15:09.840 --> 00:15:13.399
effectively frozen solid for months at a time.

00:15:13.600 --> 00:15:15.679
It's brilliant biological engineering. They aren't

00:15:15.679 --> 00:15:18.240
fighting nature. They are conducting it. So now

00:15:18.240 --> 00:15:19.919
that we have the physics down, the hysteresis,

00:15:20.059 --> 00:15:22.299
the bouncers at the door, the managed freezing,

00:15:22.580 --> 00:15:24.759
let's dive into the animals themselves. Let's

00:15:24.759 --> 00:15:26.840
do it. Because the history of how we even figure

00:15:26.840 --> 00:15:29.200
this out is a great story. Let's set the scene.

00:15:29.289 --> 00:15:32.690
It is the 1950s. We have a Norwegian scientist

00:15:32.690 --> 00:15:34.809
named Scollander. A pioneer in the field. He

00:15:34.809 --> 00:15:37.490
is out on boats in the freezing, brutal conditions

00:15:37.490 --> 00:15:40.029
of the Arctic. He is pulling up these fish from

00:15:40.029 --> 00:15:42.570
the dark water and he is just absolutely baffled.

00:15:42.610 --> 00:15:44.850
Because they should be dead. He is taking temperature

00:15:44.850 --> 00:15:47.549
readings, and the water is definitively colder

00:15:47.549 --> 00:15:50.110
than the known freezing point of the fish's blood.

00:15:50.950 --> 00:15:52.710
By all rights, the moment these fish are pulled

00:15:52.710 --> 00:15:55.269
out, or even while they are swimming, they should

00:15:55.269 --> 00:15:57.860
be solid blocks of ice floating in the sea. He

00:15:57.860 --> 00:16:00.159
suspects there must be some sort of antifreeze

00:16:00.159 --> 00:16:02.519
dissolved in their blood, but the analytical

00:16:02.519 --> 00:16:05.480
tools of the 1950s just aren't quite there to

00:16:05.480 --> 00:16:08.440
let him pin it down. He knows it's happening,

00:16:08.440 --> 00:16:11.179
but he can't prove how. It was an incredible

00:16:11.179 --> 00:16:14.120
biological mystery. It really was. It wasn't

00:16:14.120 --> 00:16:16.279
until a couple of decades later, in the late

00:16:16.279 --> 00:16:20.100
1960s, that an animal biologist named Arthur

00:16:20.100 --> 00:16:23.200
de Vries finally managed to isolate the culprit.

00:16:23.460 --> 00:16:25.120
And he was working in the Antarctic, right? He

00:16:25.120 --> 00:16:28.120
was. And through rigorous chemical isolation

00:16:28.120 --> 00:16:31.259
techniques, he discovered a unique class of molecules

00:16:31.259 --> 00:16:34.440
in their blood that he called antifreeze glycoproteins,

00:16:34.659 --> 00:16:38.019
or AFGPs. Antifreeze glycoproteins. And this

00:16:38.019 --> 00:16:40.200
discovery completely changed how we viewed cold

00:16:40.200 --> 00:16:42.539
weather biology. But my favorite part of the

00:16:42.539 --> 00:16:44.340
source material is why these fish had them in

00:16:44.340 --> 00:16:46.500
the first place. Yes. And if we connect this

00:16:46.500 --> 00:16:48.480
to the bigger picture, to understand why debris

00:16:48.480 --> 00:16:50.960
found these highly specialized proteins in Antarctic

00:16:50.960 --> 00:16:54.279
fish, we have to zoom way, way out. Like geological

00:16:54.279 --> 00:16:56.639
time scales. Exactly. We have to look back at

00:16:56.639 --> 00:16:59.340
the geological and climatic history of the entire

00:16:59.340 --> 00:17:02.240
planet. The sources detail some incredible data

00:17:02.240 --> 00:17:05.140
pulled from deep sea ocean drilling cores. Those

00:17:05.140 --> 00:17:08.460
are the literal cylinders of Earth pulled from

00:17:08.460 --> 00:17:10.799
the ocean floor. Yes. That allows scientists

00:17:10.670 --> 00:17:12.690
scientists to read the history of the planet's

00:17:12.690 --> 00:17:15.309
climate like the rings of a tree. And those cores

00:17:15.309 --> 00:17:18.529
reveal an incredible dramatic story. Over 30

00:17:18.529 --> 00:17:21.130
million years ago, a massive planet -altering

00:17:21.130 --> 00:17:23.990
geological shift occurred. The continents were

00:17:23.990 --> 00:17:26.190
shifting, and this led to the formation of the

00:17:26.190 --> 00:17:29.349
Antarctic Circumpolar Current. This is that massive,

00:17:29.670 --> 00:17:32.710
incredibly powerful ocean current that constantly,

00:17:33.089 --> 00:17:35.490
relentlessly circles the entire continent of

00:17:35.490 --> 00:17:37.589
Antarctica, right? It is. And when that current

00:17:37.589 --> 00:17:41.109
formed 30 million years ago, it effectively created

00:17:41.109 --> 00:17:44.309
a dynamic physical wall around Antarctica. Wow.

00:17:44.430 --> 00:17:46.450
It isolated the continent and its surrounding

00:17:46.450 --> 00:17:48.970
waters from the warmer, more temperate ocean

00:17:48.970 --> 00:17:50.730
currents of the rest of the globe. It basically

00:17:50.730 --> 00:17:52.940
cut off the global central heating. Exactly.

00:17:53.220 --> 00:17:55.880
This initiated a massive planetary cooling event

00:17:55.880 --> 00:17:58.039
in the southern hemisphere. The oceans around

00:17:58.039 --> 00:18:00.160
Antarctica plummeted in temperature, turning

00:18:00.160 --> 00:18:02.460
into the freezing, hostile environments we know

00:18:02.460 --> 00:18:04.460
today. And what happened to the life there? Well,

00:18:04.519 --> 00:18:07.500
as a result of this sudden, in geological terms,

00:18:07.819 --> 00:18:11.000
deep freeze, there was a mass extinction. The

00:18:11.000 --> 00:18:13.640
vast majority of Tellios species, which are the

00:18:13.640 --> 00:18:16.279
ray -finned fishes. Yes, the ray -finned fishes

00:18:16.279 --> 00:18:19.259
that populated those waters simply couldn't withstand

00:18:19.259 --> 00:18:21.740
the freezing temperatures. Their blood crystallized,

00:18:22.019 --> 00:18:24.359
their populations were decimated. It was an icy

00:18:24.359 --> 00:18:26.500
apocalypse for the fish down there, but not all

00:18:26.500 --> 00:18:30.710
of them. No. A specific, seemingly unremarkable

00:18:30.710 --> 00:18:34.490
suborder of fish called the notothenioids managed

00:18:34.490 --> 00:18:37.109
to survive. And why do they survive? Because

00:18:37.109 --> 00:18:40.410
by pure evolutionary chance, they had evolved

00:18:40.410 --> 00:18:44.309
this precise genetic adaptation. the antifreeze

00:18:44.309 --> 00:18:47.309
glycoprotein gene. Just a lucky roll of the genetic

00:18:47.309 --> 00:18:49.829
dice. While the rest of the fish died off in

00:18:49.829 --> 00:18:51.970
droves, the nototheneoids didn't just scrape

00:18:51.970 --> 00:18:55.750
by, they thrived. They diversified. They evolved

00:18:55.750 --> 00:18:57.809
into numerous different species and essentially

00:18:57.809 --> 00:19:00.750
took over all the newly emptied ecological niches

00:19:00.750 --> 00:19:02.549
left behind by the mass extinction. It's the

00:19:02.549 --> 00:19:05.029
ultimate evolutionary success story. They basically

00:19:05.029 --> 00:19:06.750
looked around and said, oh, the water is freezing

00:19:06.750 --> 00:19:09.029
and everyone else is dead. Great. More real estate

00:19:09.029 --> 00:19:11.730
for us. They inherited the entire bottom of the

00:19:11.730 --> 00:19:14.609
world because of one genetic quirk. But here's

00:19:14.609 --> 00:19:18.049
where the genetics get really, truly crazy. Our

00:19:18.049 --> 00:19:21.289
notes highlight a mind -bending fact about convergent

00:19:21.289 --> 00:19:23.650
evolution. This is one of my favorite examples.

00:19:23.710 --> 00:19:26.349
We just talked about the Antarctic nototheneoids

00:19:26.349 --> 00:19:29.190
down at the South Pole 30 million years ago.

00:19:29.569 --> 00:19:32.150
Now, I want you to look all the way up at the

00:19:32.150 --> 00:19:34.750
North Pole at a fish called the Arctic Northern

00:19:34.750 --> 00:19:37.819
Cod. Right. These two groups of fish are separated

00:19:37.819 --> 00:19:39.859
by the entire plant. They live in completely

00:19:39.859 --> 00:19:42.140
different oceans. They diverged from each other

00:19:42.140 --> 00:19:44.920
evolutionarily somewhere between 7 to 15 million

00:19:44.920 --> 00:19:47.119
years ago. They are not closely related at all.

00:19:47.339 --> 00:19:49.910
And yet... Scientists look at their blood and

00:19:49.910 --> 00:19:53.509
they both have nearly identical antifreeze glycoproteins.

00:19:53.589 --> 00:19:56.450
This is a textbook prime example of convergent

00:19:56.450 --> 00:20:00.130
evolution. Two completely unrelated species separated

00:20:00.130 --> 00:20:03.609
by thousands of miles facing the exact same brutal

00:20:03.609 --> 00:20:06.369
environmental pressure. Freezing waters. Independently

00:20:06.369 --> 00:20:08.609
arrive at the exact same biochemical solution.

00:20:09.069 --> 00:20:11.549
It is nature finding the optimal answer to a

00:20:11.549 --> 00:20:14.809
problem twice. But what is truly phenomenal,

00:20:15.289 --> 00:20:17.930
and what had geneticists thrilling, is how they

00:20:17.930 --> 00:20:20.410
arrived at that solution. They built the exact

00:20:20.410 --> 00:20:22.930
same protein, but they used entirely different

00:20:22.930 --> 00:20:25.170
genetic blueprints and raw materials to do it.

00:20:25.289 --> 00:20:27.089
Alright, I was reading about where these genes

00:20:27.089 --> 00:20:30.710
actually came from. So the Antarctic nautothenioids,

00:20:30.849 --> 00:20:34.250
they evolved their antifreeze gene from a digestive

00:20:34.250 --> 00:20:37.069
enzyme. The material specifically calls it an

00:20:37.069 --> 00:20:40.670
ancestral pancreatic, trypsinogen -like, serine,

00:20:40.730 --> 00:20:43.319
protease gene. Which is a very long way of saying

00:20:43.319 --> 00:20:45.599
it was a gene responsible for making an enzyme

00:20:45.599 --> 00:20:47.900
that breaks down food in the fish's pancreas.

00:20:48.440 --> 00:20:50.500
Exactly. So somewhere along the line over millions

00:20:50.500 --> 00:20:53.240
of years, a gene that was meant to help digest

00:20:53.240 --> 00:20:56.400
a meal accidentally duplicated, mutated, and

00:20:56.400 --> 00:20:58.279
somehow transformed into a gene that perfectly

00:20:58.279 --> 00:21:00.279
stops ice from forming in the blood. That alone

00:21:00.279 --> 00:21:02.839
is wild. But the northern cod in the Arctic.

00:21:03.279 --> 00:21:05.940
their evolutionary path was entirely different

00:21:05.940 --> 00:21:08.319
and much more recent. The sources say it happened

00:21:08.319 --> 00:21:10.900
only about 3 .2 million years ago. And their

00:21:10.900 --> 00:21:13.599
antifreeze gene didn't evolve from a pre -existing

00:21:13.599 --> 00:21:17.019
working gene like a digestive enzyme? No. It

00:21:17.019 --> 00:21:20.500
emerged from non -coding DNA. Non -coding DNA.

00:21:20.670 --> 00:21:22.609
Which is what people sometimes colloquially call

00:21:22.609 --> 00:21:26.289
junk DNA, right? Just the biological filler material

00:21:26.289 --> 00:21:28.190
that doesn't seem to do anything. Exactly. It

00:21:28.190 --> 00:21:30.130
was previously thought to be just evolutionary

00:21:30.130 --> 00:21:33.589
baggage. But the COD's antifreeze protein emerged

00:21:33.589 --> 00:21:36.369
via tandem duplications of a very short sequence

00:21:36.369 --> 00:21:39.509
of this non -coding DNA. Specifically, a tiny

00:21:39.509 --> 00:21:43.329
unit of amino acids. Thranningalaninealanine.

00:21:43.450 --> 00:21:46.029
It just duplicated over and over, right out of

00:21:46.029 --> 00:21:48.230
the dark, non -coding regions of the genome.

00:21:48.390 --> 00:21:50.990
I saw a term in the material describing this,

00:21:51.390 --> 00:21:54.710
the Proto -ORF model. I will be honest, I need

00:21:54.710 --> 00:21:56.309
you to translate that into English for me, because

00:21:56.309 --> 00:21:58.390
it sounds incredibly complex. It is a cutting

00:21:58.390 --> 00:22:01.450
edge concept in genetics. ORF stands for open

00:22:01.450 --> 00:22:03.990
reading frame. It is effectively a section of

00:22:03.990 --> 00:22:06.269
DNA that has the potential to be read and translated

00:22:06.269 --> 00:22:09.250
into a protein. The Proto -ORF model describes

00:22:09.250 --> 00:22:12.099
a very rare occurrence where a new gene essentially

00:22:12.099 --> 00:22:15.359
pre -exists as a fully formed, potentially useful

00:22:15.359 --> 00:22:18.000
sequence in the non -coding DNA. It is just sitting

00:22:18.000 --> 00:22:20.519
there in the dark, silent. Before the regulatory

00:22:20.519 --> 00:22:22.980
elements, the genetic on switches even exists

00:22:22.980 --> 00:22:26.180
to activate it. So it's like a fully built furnished

00:22:26.180 --> 00:22:28.559
house sitting in the middle of nowhere, just

00:22:28.559 --> 00:22:30.380
waiting for someone to finally run a power line

00:22:30.380 --> 00:22:33.039
to it. That is a brilliant analogy. The house

00:22:33.039 --> 00:22:35.880
is there, but the lights are off. And then boom.

00:22:36.079 --> 00:22:38.480
a massive environmental pressure like a rapidly

00:22:38.480 --> 00:22:41.200
cooling freezing ocean comes along. Through random

00:22:41.200 --> 00:22:44.380
mutation, a regulatory switch is flipped, the

00:22:44.380 --> 00:22:46.960
power line is connected, and this non -coding

00:22:46.960 --> 00:22:50.539
junk DNA suddenly illuminates and becomes a highly

00:22:50.539 --> 00:22:53.519
functional, life -saving protein. So the Cod

00:22:53.519 --> 00:22:56.440
literally hacked its own junk DNA to survive

00:22:56.440 --> 00:22:58.539
the freezing Arctic. I absolutely love that.

00:22:58.539 --> 00:23:00.299
It's incredible. But if you think that hacking

00:23:00.299 --> 00:23:02.740
your own DNA is wild, we have to talk about the

00:23:02.740 --> 00:23:05.730
smelt. Because we just discussed convergent evolution,

00:23:05.910 --> 00:23:07.990
where two animals invent the same thing independently.

00:23:08.609 --> 00:23:10.490
But there's another evolutionary curveball in

00:23:10.490 --> 00:23:12.670
the source material regarding a different type

00:23:12.670 --> 00:23:16.029
of antifreeze. Type II AFPs. These are found

00:23:16.029 --> 00:23:19.349
in three specific fish. The sea raven, the smelt,

00:23:19.470 --> 00:23:22.430
and the herring. Now, the notes point out a statistical

00:23:22.430 --> 00:23:24.829
impossibility. The smelt and the herring share

00:23:24.829 --> 00:23:27.609
up to 98 % of the introns for this specific antifreeze

00:23:27.609 --> 00:23:30.160
gene. Which, as you alluded to, is statistically

00:23:30.160 --> 00:23:33.059
impossible to achieve through independent convergent

00:23:33.059 --> 00:23:35.500
evolution. We need to define introns quickly.

00:23:35.859 --> 00:23:38.519
Introns are the non -coding sections of an RNA

00:23:38.519 --> 00:23:41.079
transcript. When a cell reads a gene to make

00:23:41.079 --> 00:23:43.799
a protein, it makes a rough draft of RNA, and

00:23:43.799 --> 00:23:46.200
then it literally splices out and throws away

00:23:46.200 --> 00:23:48.640
the introns before the final protein is made.

00:23:48.880 --> 00:23:51.500
They are the cutting room floor scraps of genetics.

00:23:51.779 --> 00:23:55.269
Precisely. Now, for two widely divergent lineages

00:23:55.269 --> 00:23:57.990
of fish, the smelt and the herring, to share

00:23:57.990 --> 00:24:02.009
98 % of these highly specific, seemingly useless

00:24:02.009 --> 00:24:04.829
cutting room floor sequences implies something

00:24:04.829 --> 00:24:07.589
much, much more direct than convergent evolution.

00:24:08.160 --> 00:24:10.740
The smelt didn't independently evolve this gene

00:24:10.740 --> 00:24:13.660
over millions of years. The scientific consensus,

00:24:13.920 --> 00:24:16.779
backed by undeniable genomic evidence, is that

00:24:16.779 --> 00:24:18.880
the smelt actually stole it from the herring.

00:24:19.079 --> 00:24:21.099
I'm sorry, I need to pause here. Yeah. They stole

00:24:21.099 --> 00:24:23.960
a gene. Yes. Like a genetic heist. Yeah. How

00:24:23.960 --> 00:24:26.299
does a fish steal a gene from another fish? It

00:24:26.299 --> 00:24:28.759
is a phenomenon known as horizontal or lateral

00:24:28.759 --> 00:24:30.900
gene transfer. We see it all the time in bacteria.

00:24:31.140 --> 00:24:33.599
It's how they share antibiotic resistance so

00:24:33.599 --> 00:24:37.009
quickly. But it is extremely, exceedingly rare

00:24:37.009 --> 00:24:40.230
in complex vertebrates like fish. The theory,

00:24:40.410 --> 00:24:42.670
which is heavily supported by the presence of

00:24:42.670 --> 00:24:44.930
transposable elements. Basically jumping genes.

00:24:45.269 --> 00:24:48.210
Exactly. Jumping genes in the smelt gene that

00:24:48.210 --> 00:24:50.309
are otherwise uniquely characteristic of the

00:24:50.309 --> 00:24:52.670
herring. The theory is that this transfer happened

00:24:52.670 --> 00:24:55.250
during mating. Wait, herring and smelt don't

00:24:55.250 --> 00:24:57.799
mate with each other, do they? No, but they do

00:24:57.799 --> 00:25:00.839
spawn in the same freezing chaotic water columns.

00:25:01.400 --> 00:25:04.380
It is believed that during spawning, smelt sperm

00:25:04.380 --> 00:25:08.200
cells were somehow exposed to degraded or free

00:25:08.200 --> 00:25:10.920
-floating foreign herring DNA in the water. Just

00:25:10.920 --> 00:25:13.180
floating around. Through a microscopic stroke

00:25:13.180 --> 00:25:16.059
of unimaginable statistical luck, a smelt sperm

00:25:16.059 --> 00:25:18.940
cell absorbed that herring DNA, integrated the

00:25:18.940 --> 00:25:21.740
antifreeze gene into its own payload, and then

00:25:21.740 --> 00:25:24.900
successfully fertilized a smelt egg. That is

00:25:24.900 --> 00:25:27.359
staggering. A microscopic sperm cell just bumps

00:25:27.359 --> 00:25:29.539
into some floating genetic debris from a completely

00:25:29.539 --> 00:25:32.400
different species, absorbs it, and suddenly the

00:25:32.400 --> 00:25:35.019
entire subsequent lineage of smelt has a survival

00:25:35.019 --> 00:25:37.579
superpower. They literally acquired it horizontally

00:25:37.579 --> 00:25:41.240
across species lines. It totally upends the idea

00:25:41.240 --> 00:25:44.019
of evolution being this slow branching tree.

00:25:44.319 --> 00:25:46.220
It's more like a tangled web where sometimes

00:25:46.220 --> 00:25:48.460
you just grab a power up from the guy swimming

00:25:48.460 --> 00:25:50.819
next to you. It truly is a paradigm shifting

00:25:50.819 --> 00:25:53.920
discovery in evolutionary biology. It shows how

00:25:53.920 --> 00:25:56.240
opportunistic life can be. can be under extreme

00:25:56.240 --> 00:25:59.460
pressure. Nature is absolutely wild. And just

00:25:59.460 --> 00:26:01.480
to show you that, listen, the sheer diversity

00:26:01.480 --> 00:26:04.599
of these proteins, the sources give us a roster

00:26:04.599 --> 00:26:08.240
of different fish AFPs. We've talked deeply about

00:26:08.240 --> 00:26:11.059
the glycoproteins. But there are four other completely

00:26:11.059 --> 00:26:14.200
distinct structural types of antifreeze proteins

00:26:14.200 --> 00:26:16.539
in fish. Let's run through them quickly, because

00:26:16.539 --> 00:26:18.519
I want to give a sense of how many ways nature

00:26:18.519 --> 00:26:21.799
solves this one problem. OK. First, there's type

00:26:21.799 --> 00:26:24.460
I. This is found in the winter flounder and various

00:26:24.460 --> 00:26:27.039
sculpins. The material notes that this is the

00:26:27.039 --> 00:26:29.339
best documented one because it was the first

00:26:29.339 --> 00:26:31.960
to have its 3D structure fully mapped out by

00:26:31.960 --> 00:26:35.460
scientists. It looks like a single long amphipathic

00:26:35.460 --> 00:26:38.319
alpha helix. Let's clarify that term amphipathic

00:26:38.319 --> 00:26:40.460
because it is crucial to how these proteins work.

00:26:40.859 --> 00:26:43.059
Amphipathic means the molecule has distinct faces

00:26:43.059 --> 00:26:45.859
with entirely different properties. Imagine a

00:26:45.859 --> 00:26:49.029
long cylinder. One side of the cylinder is highly

00:26:49.029 --> 00:26:51.789
hydrophobic, meaning it actively repels water.

00:26:52.349 --> 00:26:55.089
The opposite side is hydrophilic, meaning it

00:26:55.089 --> 00:26:57.730
attracts water. Got it. And nestled within this

00:26:57.730 --> 00:27:01.410
structure is a highly specific face made of threonine

00:27:01.410 --> 00:27:04.509
and asparagine amino acids. This exact architectural

00:27:04.509 --> 00:27:06.589
arrangement is what allows it to bind to ice,

00:27:06.730 --> 00:27:08.890
which we will detail much more closely when we

00:27:08.890 --> 00:27:11.009
look at the micromechanics. OK, so a two -faced

00:27:11.009 --> 00:27:13.710
cylinder. Then you have type I hip. And hip simply

00:27:13.710 --> 00:27:16.400
stands for hyperactive. found in right eye flounders.

00:27:16.460 --> 00:27:18.480
And compared to the standard type I, it is a

00:27:18.480 --> 00:27:20.940
massive molecule. The notes say it's about 32

00:27:20.940 --> 00:27:24.640
kilodaltons, making it a dimeric molecule. Domeric

00:27:24.640 --> 00:27:27.059
simply meaning it is composed of two identical

00:27:27.059 --> 00:27:29.859
halves or monomers bound together. It operates

00:27:29.859 --> 00:27:32.500
as a twin system. Right. And because of this

00:27:32.500 --> 00:27:36.119
massive twin structure, it is incredibly effective

00:27:36.119 --> 00:27:39.299
at depressing freezing temperatures. It has multiple

00:27:39.299 --> 00:27:41.839
ice binding sites. It's like having an antifreeze

00:27:41.839 --> 00:27:44.180
molecule with extra hands to grab onto the ice

00:27:44.180 --> 00:27:46.480
crystal from multiple angles. Following that,

00:27:46.579 --> 00:27:49.279
we have the type 3 AFPs, which are found in the

00:27:49.279 --> 00:27:51.720
Antarctic eel pout. These are fascinating because,

00:27:51.920 --> 00:27:53.819
similar to the digestive enzyme we discussed

00:27:53.819 --> 00:27:57.000
earlier, they evolved from a completely different

00:27:57.000 --> 00:28:00.460
functional gene. In this case, a sialic acid

00:28:00.460 --> 00:28:04.220
synthase gene, or SAS. Through a complex gene

00:28:04.220 --> 00:28:07.450
duplication event? This SAS gene actually lost

00:28:07.450 --> 00:28:10.049
its N -terminal part. It basically lost a chunk

00:28:10.049 --> 00:28:12.089
of itself. And the remaining fragment evolved

00:28:12.089 --> 00:28:16.210
into a highly compact, globular, highly effective

00:28:16.210 --> 00:28:19.329
antifreeze protein. It shows yet another completely

00:28:19.329 --> 00:28:22.089
unique evolutionary pathway. And finally, type

00:28:22.089 --> 00:28:25.369
4, found in longhorn sculpins. This one is an

00:28:25.369 --> 00:28:27.829
alpha helical bundle. It's incredibly rich in

00:28:27.829 --> 00:28:31.269
glutamate and glutamine amino acids. Just stepping

00:28:31.269 --> 00:28:34.230
back for a second. In fish alone, we have at

00:28:34.230 --> 00:28:36.809
least five completely distinct structural molecules.

00:28:37.289 --> 00:28:39.829
Blycoproteins, type I cylinders, type I hyperactive

00:28:39.829 --> 00:28:42.369
twins, type III globular fragments, and type

00:28:42.369 --> 00:28:44.490
IV bundles. They all look completely different.

00:28:44.549 --> 00:28:46.430
They all evolve completely independently. And

00:28:46.430 --> 00:28:48.390
they're all designed to do the exact same thing.

00:28:48.869 --> 00:28:51.609
Stop ice. It's a testament to evolutionary pressure.

00:28:51.930 --> 00:28:54.630
But as we pivot away from the ocean, we learn

00:28:54.630 --> 00:28:57.349
that the macrofauna, the big fish, are not the

00:28:57.349 --> 00:28:59.660
only ones playing this high stakes game. We have

00:28:59.660 --> 00:29:01.259
to look at the micro world. We have to look at

00:29:01.259 --> 00:29:03.599
the microbes, the fungi, and the fascinating

00:29:03.599 --> 00:29:06.259
paradox of plants. Let's start with the sea ice

00:29:06.259 --> 00:29:08.480
ecosystem. When you look at a documentary about

00:29:08.480 --> 00:29:11.859
the polar ice caps, the ice just looks like dead

00:29:11.859 --> 00:29:15.579
frozen sterile water. But it's not. It is absolutely

00:29:15.579 --> 00:29:18.220
teeming with life. Diatoms, which are a type

00:29:18.220 --> 00:29:21.599
of microscopic algae absolutely dominate the

00:29:21.599 --> 00:29:24.880
polar sea ice communities. Specifically, species

00:29:24.880 --> 00:29:27.539
like Fragillaryopsis cylindrus. Yes, and these

00:29:27.539 --> 00:29:30.920
diatoms possess AFPs that belong to a large complex

00:29:30.920 --> 00:29:33.700
multi -gene family. They need them because they

00:29:33.700 --> 00:29:36.259
actually live inside the tiny, brine -filled

00:29:36.259 --> 00:29:38.700
channels within the sea ice itself. But what

00:29:38.700 --> 00:29:41.119
is really intriguing about this specific family

00:29:41.119 --> 00:29:43.839
of ice -binding proteins is that it isn't just

00:29:43.839 --> 00:29:46.299
found in diatoms. The exact same homologs are

00:29:46.299 --> 00:29:48.700
represented across wildly different unrelated

00:29:48.700 --> 00:29:51.970
taxa. in the sea ice ecosystem. You find variations

00:29:51.970 --> 00:29:54.369
of these ice binding proteins in psychrophilic

00:29:54.369 --> 00:29:57.049
or cold loving bacteria. You find them in cold

00:29:57.049 --> 00:29:59.589
tolerant fungi like the snow mold fungi that

00:29:59.589 --> 00:30:01.809
survive under the winter pack snow. And wait,

00:30:01.809 --> 00:30:03.549
I have to bring this up because it shocked me.

00:30:03.880 --> 00:30:06.599
The notes say you even find them in edible mushrooms,

00:30:07.039 --> 00:30:09.980
like the enoki and shiitake mushrooms. They absolutely

00:30:09.980 --> 00:30:12.220
do. The enoki mushrooms I literally put in my

00:30:12.220 --> 00:30:15.099
ramen last week have antifreeze proteins. They

00:30:15.099 --> 00:30:17.680
do. It's how they survive sudden frosts in their

00:30:17.680 --> 00:30:20.599
natural environments. Wow. And the fact that

00:30:20.599 --> 00:30:24.099
we find this same family of proteins in diatoms,

00:30:24.380 --> 00:30:26.559
bacteria, snow mold, and your dinner mushrooms

00:30:26.559 --> 00:30:29.640
points to one of two things. What's that? Either...

00:30:29.880 --> 00:30:33.319
There is a deeply ancient shared ancestral origin

00:30:33.319 --> 00:30:35.900
for these proteins among all microorganisms dating

00:30:35.900 --> 00:30:39.400
back hundreds of millions of years. Or... Or

00:30:39.400 --> 00:30:42.380
we are looking at an incredibly vast complex

00:30:42.380 --> 00:30:44.980
network of horizontal gene transfer. Like the

00:30:44.980 --> 00:30:47.019
smell to the herring. Occurring constantly in

00:30:47.019 --> 00:30:49.619
the microscopic sea ice community. The idea of

00:30:49.619 --> 00:30:52.180
a global microscopic gene sharing network under

00:30:52.180 --> 00:30:54.740
the ice is incredible. Okay, but my absolute

00:30:54.740 --> 00:30:57.279
favorite microbe from the source material has

00:30:57.279 --> 00:31:01.680
to be the ciliate consortium. This little single

00:31:01.680 --> 00:31:04.359
-celled organism has an ice -binding protein

00:31:04.359 --> 00:31:08.900
called AFC -IBP, and it is an absolute masterclass

00:31:08.900 --> 00:31:11.440
in freeze tolerance. It is a perfect example

00:31:11.440 --> 00:31:13.680
of what we discussed earlier. Remember our distinction

00:31:13.680 --> 00:31:15.900
between freeze tolerance versus freeze avoidance.

00:31:16.190 --> 00:31:18.910
The Euclid's Fecardiae protein doesn't focus

00:31:18.910 --> 00:31:22.069
entirely on creating a massive thermal hysteresis

00:31:22.069 --> 00:31:25.349
gap to prevent ice formation entirely. Instead,

00:31:25.609 --> 00:31:28.250
it is exceptionally good at ice recrystallization

00:31:28.250 --> 00:31:30.289
inhibition. It works efficiently all the way

00:31:30.289 --> 00:31:33.789
down to a staggering negative 7 .4 degrees Celsius.

00:31:34.410 --> 00:31:36.789
It allows the ice to form around it, but perfectly

00:31:36.789 --> 00:31:39.109
manages the crystal size to prevent its single

00:31:39.109 --> 00:31:41.809
cell from being punctured. And the science gets

00:31:41.809 --> 00:31:44.599
even cooler. Researchers actually took the specific

00:31:44.599 --> 00:31:47.480
gene for this Euclid's Focardianta freeze protein,

00:31:47.720 --> 00:31:50.559
isolated it, and inserted it into the genome

00:31:50.559 --> 00:31:53.339
of standard E. coli bacteria in a lab. And the

00:31:53.339 --> 00:31:56.460
result? The newly modified E. coli survived significantly

00:31:56.460 --> 00:31:59.380
longer periods at zero degrees Celsius. This

00:31:59.380 --> 00:32:02.059
little single -celled ciliates genetic code is

00:32:02.059 --> 00:32:04.160
so robust, so perfectly engineered by nature,

00:32:04.480 --> 00:32:06.619
that you just plug it into a standard lab bacterium

00:32:06.619 --> 00:32:09.000
like a software update and instantly upgrade

00:32:09.000 --> 00:32:11.460
its cold resistance. Which, as you can imagine,

00:32:11.599 --> 00:32:14.220
has massive implications for biotechnology and

00:32:14.220 --> 00:32:16.279
synthetic biology, which we will certainly get

00:32:16.279 --> 00:32:18.960
to. But first, we need to address the plants.

00:32:19.460 --> 00:32:21.960
Because as the sources note, the classification

00:32:21.960 --> 00:32:24.640
of AFPs became much, much more complicated in

00:32:24.640 --> 00:32:27.680
the 1990s when antifreeze proteins were finally

00:32:27.680 --> 00:32:30.380
discovered in plants, specifically in winter

00:32:30.380 --> 00:32:33.319
rye leaves. The plant exception. So I'm picturing

00:32:33.319 --> 00:32:37.130
a field of winter rye covered in snow. What makes

00:32:37.130 --> 00:32:39.890
plant AFPs so fundamentally different from the

00:32:39.890 --> 00:32:41.690
fish and the microbes we've been talking about?

00:32:41.970 --> 00:32:44.869
What's fascinating here is that plant AFPs, which

00:32:44.869 --> 00:32:47.910
are often classified by botanists as dehydrins,

00:32:48.470 --> 00:32:51.210
operate on a slightly different biological paradigm.

00:32:51.509 --> 00:32:53.750
First off, if you measure them, they exhibit

00:32:53.920 --> 00:32:57.119
much weaker thermal hysteresis activity compared

00:32:57.119 --> 00:32:59.940
to the hyperactive fish or insect AFPs. Their

00:32:59.940 --> 00:33:02.359
primary physiological function isn't really to

00:33:02.359 --> 00:33:04.619
prevent ice formation altogether. They know they're

00:33:04.619 --> 00:33:07.500
going to freeze. They can't swim away to deeper,

00:33:07.900 --> 00:33:10.319
warmer water. They're literally rooted in the

00:33:10.319 --> 00:33:13.440
freezing ground. Exactly. They are entirely immobile.

00:33:13.960 --> 00:33:16.480
So like the ciliate we just discussed, they are

00:33:16.480 --> 00:33:19.299
heavily focused on managing the inevitable. They

00:33:19.299 --> 00:33:22.160
inhibit the recrystallization of ice. They let

00:33:22.160 --> 00:33:24.960
the water in their cellular spaces freeze, but

00:33:24.960 --> 00:33:27.220
the dehydrants stop those ice crystals from growing

00:33:27.220 --> 00:33:30.039
large enough to shred the plant's delicate vascular

00:33:30.039 --> 00:33:32.599
system. They are the elegant managers of the

00:33:32.599 --> 00:33:35.480
cold. They let the frost in, but they dictate

00:33:35.480 --> 00:33:37.940
the terms. But the evolutionary origin of these

00:33:37.940 --> 00:33:40.400
plant proteins is what really caught my eye in

00:33:40.400 --> 00:33:42.619
the reading, because it's a completely different

00:33:42.619 --> 00:33:44.740
origin story than the digestive enzymes of the

00:33:44.740 --> 00:33:48.400
fish. It is a brilliant, highly resourceful pivot

00:33:48.400 --> 00:33:51.799
by nature. Analysis shows that most plant AFPs

00:33:51.799 --> 00:33:54.539
actually evolved from pathogenesis -related proteins.

00:33:54.880 --> 00:33:57.059
Pathogenesis. Yeah. Meaning proteins that originally

00:33:57.059 --> 00:33:59.819
evolved to fight off diseases. Precisely. They

00:33:59.819 --> 00:34:01.960
originally evolved as defense mechanisms to fight

00:34:01.960 --> 00:34:04.619
off fungal infections and other pathogens. And

00:34:04.619 --> 00:34:07.079
what is truly remarkable, what makes it a biological

00:34:07.079 --> 00:34:09.619
marvel, is that some of these plant antifreeze

00:34:09.619 --> 00:34:12.440
proteins still retain their original antifungal

00:34:12.440 --> 00:34:14.929
properties. They are pulling double duty. They

00:34:14.929 --> 00:34:17.389
are protecting the plant from deadly, expanding

00:34:17.389 --> 00:34:20.849
ice crystals in the dead of winter, while simultaneously

00:34:20.849 --> 00:34:24.090
fighting off opportunistic fungal pathogens that

00:34:24.090 --> 00:34:26.349
might try to take advantage of the stressed freezing

00:34:26.349 --> 00:34:29.809
plant. It's a two -for -one survival tool, a

00:34:29.809 --> 00:34:33.349
shield against both ice and disease. It is incredibly

00:34:33.349 --> 00:34:36.340
elegant. but if plants are the elegant managers

00:34:36.340 --> 00:34:39.599
of the gold, kinsects are the absolute biological

00:34:39.599 --> 00:34:41.719
tanks. Here's where it gets really interesting.

00:34:41.940 --> 00:34:44.000
You think a fish surviving at negative two degrees

00:34:44.000 --> 00:34:47.019
Celsius is impressive. Our sources introduce

00:34:47.019 --> 00:34:50.300
us to the spruce budworm. During the extreme

00:34:50.300 --> 00:34:53.079
brutal winter months in northern forests, this

00:34:53.079 --> 00:34:56.099
little moth larva resists freezing at temperatures

00:34:56.099 --> 00:34:58.199
approaching negative 30 degrees Celsius. Just

00:34:58.199 --> 00:35:00.639
for context, that is negative 22 degrees Fahrenheit.

00:35:00.699 --> 00:35:03.570
It is unimaginably cold. To survive temperatures

00:35:03.570 --> 00:35:06.110
that extreme, the proteins involved have to be

00:35:06.110 --> 00:35:08.690
incredibly robust. Insect AFPs are generally

00:35:08.690 --> 00:35:10.769
referred to in the literature as hyperactive.

00:35:10.989 --> 00:35:13.570
They have a significantly greater thermal hysteresis

00:35:13.570 --> 00:35:16.329
value than most fish AFPs. They have to because

00:35:16.329 --> 00:35:18.750
the air temperatures they face are vastly colder

00:35:18.750 --> 00:35:22.150
than any liquid ocean. Structurally, insect AFPs

00:35:22.150 --> 00:35:24.909
are highly repetitive. They form a shape that

00:35:24.909 --> 00:35:28.769
biochemists call a beta solenoid or a coil structure.

00:35:28.969 --> 00:35:32.070
I was trying to visualize this. Imagine a tightly

00:35:32.070 --> 00:35:35.389
wound spring, like from a mattress, but instead

00:35:35.389 --> 00:35:38.090
of being perfectly round, one entire side of

00:35:38.090 --> 00:35:40.610
the spring is completely flattened out. That

00:35:40.610 --> 00:35:43.239
flat side is the ice binding surface. That is

00:35:43.239 --> 00:35:46.039
a highly accurate visualization. And nature has

00:35:46.039 --> 00:35:48.880
engineered several distinct variations of this

00:35:48.880 --> 00:35:51.360
flattened coil across different species of bugs.

00:35:51.440 --> 00:35:53.420
For instance, let's look at the tenebrio and

00:35:53.420 --> 00:35:55.539
dendroids beetles. Their proteins are heavily

00:35:55.539 --> 00:35:58.059
reinforced. They have internal disulfide bonds

00:35:58.059 --> 00:36:00.679
that act like microscopic structural braces,

00:36:01.199 --> 00:36:03.820
holding the coils rigidly together. And on that

00:36:03.820 --> 00:36:06.019
flat ice -binding side of the coil, they have

00:36:06.019 --> 00:36:08.599
a double row of an amino acid called threonine.

00:36:08.659 --> 00:36:11.079
It's like armored plating. Very much so. But

00:36:11.079 --> 00:36:13.809
then compare that to the rage their proteins

00:36:13.809 --> 00:36:15.909
have even longer repeats. They don't rely on

00:36:15.909 --> 00:36:18.789
those internal disulfide bonds for bracing. Instead,

00:36:19.010 --> 00:36:21.070
they form what is called a compressed beta sandwich

00:36:21.070 --> 00:36:24.019
structure. And instead of a double row, they

00:36:24.019 --> 00:36:27.440
boast a formidable four rows of threonine residues

00:36:27.440 --> 00:36:29.920
on their ice binding surface. They maximize the

00:36:29.920 --> 00:36:31.860
contact area with the ice. And then you have

00:36:31.860 --> 00:36:34.219
the midges, which use a structurally similar

00:36:34.219 --> 00:36:37.480
solenoid coil. But their flat ice binding surface

00:36:37.480 --> 00:36:40.119
consists of a single row of tyrosine residues

00:36:40.119 --> 00:36:42.440
instead of threonine. It's exactly like looking

00:36:42.440 --> 00:36:44.460
at different models of armored vehicles. They

00:36:44.460 --> 00:36:47.139
all have the exact same goal, survive the battlefield

00:36:47.139 --> 00:36:49.980
of winter. But the armor plating, the internal

00:36:49.980 --> 00:36:52.719
bracing, the structural layout is arranged completely

00:36:52.719 --> 00:36:54.840
differently depending on the specific evolutionary

00:36:54.840 --> 00:36:57.260
path they took. But then I asked about the snow

00:36:57.260 --> 00:36:59.679
fleas, because they are famous here in North

00:36:59.679 --> 00:37:02.079
America, especially in Canada. You see them literally

00:37:02.079 --> 00:37:04.460
hopping around on the surface of the snow on

00:37:04.460 --> 00:37:07.719
relatively warm winter days. They aren't actually

00:37:07.719 --> 00:37:10.500
true insects. They are springtails, which are

00:37:10.500 --> 00:37:13.719
a type of primitive six -legged arthropod. And

00:37:13.719 --> 00:37:17.079
their AFPs, despite living in the snow, are totally

00:37:17.079 --> 00:37:19.090
different from the beetles, right? Completely

00:37:19.090 --> 00:37:21.389
different. The similarity entirely ends at the

00:37:21.389 --> 00:37:23.550
fact that they have a flat ice -binding surface.

00:37:24.130 --> 00:37:26.929
The snow flea AFP is roughly 50 % composed of

00:37:26.929 --> 00:37:29.769
the amino acid glycine. It doesn't form a beta

00:37:29.769 --> 00:37:32.949
solenoid coil. Instead, it folds into a dense

00:37:32.949 --> 00:37:35.630
bundle of what are called polyproline type 2

00:37:35.630 --> 00:37:39.210
helices. And instead of using threonine or tyrosine

00:37:39.210 --> 00:37:41.590
to bind to the ice like the beetles and midges,

00:37:42.010 --> 00:37:45.809
its ice -binding face is dominated by small hydrophobic

00:37:45.809 --> 00:37:49.409
residues like alanine. Again, convergent evolution.

00:37:50.489 --> 00:37:53.389
A totally different genetic path, a totally different

00:37:53.389 --> 00:37:56.110
molecular shape, but they still arise at a flat

00:37:56.110 --> 00:37:58.949
surface that perfectly sticks to ice. But I want

00:37:58.949 --> 00:38:00.809
to drop a bombshell from the sources right now.

00:38:00.829 --> 00:38:03.070
Freeze you. Because we have spent this entire

00:38:03.070 --> 00:38:05.809
deep dive talking about antifreeze proteins,

00:38:06.269 --> 00:38:09.650
the P in AFP, amino acids folding into complex

00:38:09.650 --> 00:38:12.760
shapes. But the Alaskan beetle... scientifically

00:38:12.760 --> 00:38:15.679
known as upocereboids, has an antifreeze that

00:38:15.679 --> 00:38:18.079
isn't even a protein at all. This was a landmark

00:38:18.079 --> 00:38:19.739
discovery published in the Proceedings of the

00:38:19.739 --> 00:38:22.940
National Academy of Sciences in 2009. It challenged

00:38:22.940 --> 00:38:24.920
everything we thought we knew about cryobiology.

00:38:25.260 --> 00:38:28.280
The Alaskan beetle produces a hyperactive antifreeze

00:38:28.280 --> 00:38:30.619
molecule that is actually a non -protein polymer.

00:38:31.159 --> 00:38:33.500
It is composed of saccharides and fatty acids.

00:38:34.000 --> 00:38:36.980
It's a complex sugar polymer known as a xylomanin.

00:38:37.019 --> 00:38:39.960
A sugar antifreeze. Exactly. It uses a chain

00:38:39.960 --> 00:38:42.960
of sugars to do the exact same job as the complex

00:38:42.960 --> 00:38:46.679
beta -solenoid proteins. It proves, unequivocally,

00:38:47.079 --> 00:38:49.639
that nature found multiple, completely independent,

00:38:50.039 --> 00:38:53.219
radically different biochemical pathways to fight

00:38:53.219 --> 00:38:55.679
freezing. Evolution isn't restricted to just

00:38:55.679 --> 00:38:58.340
rearranging amino acids into proteins. It can

00:38:58.340 --> 00:39:00.960
literally build a highly effective, hyperactive

00:39:00.960 --> 00:39:03.639
ice blocking shield out of complex sugars and

00:39:03.639 --> 00:39:06.190
fats. That is staggering to me. It really makes

00:39:06.190 --> 00:39:08.570
you wonder what else is out there in the extreme

00:39:08.570 --> 00:39:10.550
environments of our planet that we simply haven't

00:39:10.550 --> 00:39:13.369
discovered yet. What other bizarre molecular

00:39:13.369 --> 00:39:16.250
combinations are keeping bugs alive in Siberia

00:39:16.250 --> 00:39:18.590
or the deep Arctic? But whether it's a sugar

00:39:18.590 --> 00:39:21.590
polymer like the xylomanin or a heavily armored

00:39:21.590 --> 00:39:24.349
beta solenoid protein in a beetle or a microscopic

00:39:24.349 --> 00:39:27.230
zipper in a flounder, it begs the ultimate mechanical

00:39:27.230 --> 00:39:30.090
question. How does it physically work? How does

00:39:30.090 --> 00:39:32.630
a tiny microscopic molecule actually grab onto

00:39:32.630 --> 00:39:35.670
something as slippery, as rigid, and as dynamically

00:39:35.670 --> 00:39:37.789
growing as an ice crystal? It all comes down

00:39:37.789 --> 00:39:39.889
to a process that scientists call the adsorption

00:39:39.889 --> 00:39:42.610
inhibition mechanism. To truly visualize this,

00:39:42.949 --> 00:39:45.250
you have to understand how ice naturally grows

00:39:45.250 --> 00:39:48.070
at a microscopic level. When water begins to

00:39:48.070 --> 00:39:50.800
freeze in a solution, The water molecules slow

00:39:50.800 --> 00:39:54.260
down and form a lattice. These nascent ice crystals

00:39:54.260 --> 00:39:56.559
normally exhibit what crystallographers call

00:39:56.559 --> 00:39:59.780
basal and prism faces. They tend to grow outward

00:39:59.780 --> 00:40:03.840
as round, flat disks. Okay, so picture a microscopic,

00:40:04.260 --> 00:40:07.630
dynamically growing Hockey puck. Exactly. The

00:40:07.630 --> 00:40:09.670
hockey puck wants to keep expanding outward,

00:40:10.070 --> 00:40:12.710
adding water molecules to its edges. What the

00:40:12.710 --> 00:40:15.429
antifreeze proteins do is they target and adsorb,

00:40:15.590 --> 00:40:17.650
meaning they physically adhere to the surface

00:40:17.650 --> 00:40:20.050
of the non -basal planes of the ice crystal.

00:40:20.389 --> 00:40:23.030
By attaching themselves to these specific structural

00:40:23.030 --> 00:40:25.269
faces of the ice lattice, they create physical

00:40:25.269 --> 00:40:27.579
roadblocks. They block the crystal from growing

00:40:27.579 --> 00:40:30.019
in its thermodynamically favored direction. It's

00:40:30.019 --> 00:40:31.760
like trying to build a brick wall and someone

00:40:31.760 --> 00:40:34.820
keeps gluing unstackable steel plates randomly

00:40:34.820 --> 00:40:36.699
onto your bricks. You just can't keep building.

00:40:36.980 --> 00:40:40.420
But how do the proteins actually stick? Ice is

00:40:40.420 --> 00:40:42.900
incredibly slippery. Because initially, according

00:40:42.900 --> 00:40:44.880
to the sources, scientists thought it was all

00:40:44.880 --> 00:40:47.250
about hydrogen bonding. Like the proteins were

00:40:47.250 --> 00:40:49.909
tiny molecular magnets locking onto the oxygen

00:40:49.909 --> 00:40:52.250
and hydrogen atoms in the water molecules of

00:40:52.250 --> 00:40:55.250
the ice. That was indeed the prevailing, widely

00:40:55.250 --> 00:40:57.769
accepted theory proposed by Raymond and de Vries,

00:40:58.349 --> 00:41:00.989
the pioneer we mentioned earlier, back in 1977.

00:41:01.610 --> 00:41:04.500
It made intuitive sense. However, biology and

00:41:04.500 --> 00:41:07.480
physical chemistry are rarely that simple. Later

00:41:07.480 --> 00:41:10.400
researchers decided to rigorously test this hydrogen

00:41:10.400 --> 00:41:13.480
bonding theory by purposefully mutating the proteins

00:41:13.480 --> 00:41:17.059
in the lab. They systematically altered or removed

00:41:17.059 --> 00:41:19.599
the specific parts of the protein that were supposed

00:41:19.599 --> 00:41:22.340
to be facilitating this magnetic -like hydrogen

00:41:22.340 --> 00:41:25.420
bonding. If the 1977 theory held up perfectly,

00:41:25.780 --> 00:41:28.079
the mutated proteins should have completely failed

00:41:28.079 --> 00:41:30.000
to bind to the ice. They should have been useless.

00:41:30.179 --> 00:41:33.349
But they weren't. The hypothesized massive decrease

00:41:33.349 --> 00:41:35.929
in antifreeze activity was not observed. The

00:41:35.929 --> 00:41:38.489
mutated proteins still stopped the ice. Which

00:41:38.489 --> 00:41:40.690
means hydrogen bonding wasn't the main anchor

00:41:40.690 --> 00:41:43.010
holding them there, so if it's not a magnetic

00:41:43.010 --> 00:41:44.690
attraction, what is actually holding them to

00:41:44.690 --> 00:41:47.250
this slippery ice? The current scientific consensus,

00:41:47.510 --> 00:41:49.809
derived from decades of intense study, X -ray

00:41:49.809 --> 00:41:51.869
crystallography, and advanced molecular modeling

00:41:51.869 --> 00:41:55.170
programs, points to a highly complex mix of interactions.

00:41:55.710 --> 00:41:58.710
Van der Waals forces, which are very weak, distance

00:41:58.710 --> 00:42:01.539
-dependent intermolecular forces, play a significant

00:42:01.539 --> 00:42:04.619
role. Along with that is surface complementarity.

00:42:04.960 --> 00:42:06.900
Essentially, the physical shape of the protein

00:42:06.900 --> 00:42:09.800
perfectly flawlessly matches the microscopic

00:42:09.800 --> 00:42:12.460
physical topography of the ice crystal, locking

00:42:12.460 --> 00:42:14.840
together like an impossibly complex puzzle piece.

00:42:15.119 --> 00:42:17.719
But the primary driving force, the main contributor,

00:42:17.900 --> 00:42:20.480
seems to be largely hydrophobic interactions.

00:42:20.719 --> 00:42:23.139
Hyndrophobic meaning water repelling. So the

00:42:23.139 --> 00:42:25.900
protein basically uses its water repelling side

00:42:25.900 --> 00:42:28.659
to forcefully push away the liquid water in the

00:42:28.659 --> 00:42:31.519
blood, which effectively forces its other flat

00:42:31.519 --> 00:42:34.440
complementary side perfectly against the solid

00:42:34.440 --> 00:42:37.380
ice matrix. Yes. And we can look back at the

00:42:37.380 --> 00:42:40.679
type IAFPs from the winter flounder as a prime,

00:42:40.920 --> 00:42:43.719
easily visualizable example of this micromechanic

00:42:43.719 --> 00:42:47.039
in action. Because of its amphipathic, two -faced

00:42:47.039 --> 00:42:50.099
structure, it acts quite literally like a microscopic

00:42:50.099 --> 00:42:53.280
zipper. The hydroxyl groups of the critical threonine

00:42:53.280 --> 00:42:55.460
residues on the flat side of the protein align

00:42:55.460 --> 00:42:57.739
perfectly to bind to the oxygen atoms in the

00:42:57.739 --> 00:43:00.159
ice lattice along a very specific directional

00:43:00.159 --> 00:43:03.039
plane. It literally zips itself onto the ice

00:43:03.039 --> 00:43:06.519
nucleation structure. Once zipped on, it creates

00:43:06.519 --> 00:43:09.480
a rigid barrier, subsequently regarding the growth

00:43:09.480 --> 00:43:11.579
of the pyramidal planes of the ice and depressing

00:43:11.579 --> 00:43:14.639
the freeze point. A microscopic zipper driven

00:43:14.639 --> 00:43:17.840
by water repulsion holding a growing ice crystal,

00:43:18.199 --> 00:43:21.000
completely hostage. It's almost poetry. But our

00:43:21.000 --> 00:43:23.559
sources also tell us that these biological zippers

00:43:23.559 --> 00:43:26.159
don't always work entirely alone. Sometimes they

00:43:26.159 --> 00:43:27.940
bring friends to the fight to make sure the ice

00:43:27.940 --> 00:43:30.260
stays locked down. Yes, in the literature we

00:43:30.260 --> 00:43:32.820
call these secondary molecules enhancers. In

00:43:32.820 --> 00:43:35.099
beetles, for example, the highly hyperactive

00:43:35.099 --> 00:43:37.880
antifreeze proteins are often accompanied by

00:43:37.880 --> 00:43:40.119
other molecules circulating in their hemolymph,

00:43:40.159 --> 00:43:43.199
their equivalent of blood. These include polycarboxylates,

00:43:43.619 --> 00:43:45.599
specifically citrate and other compounds called

00:43:45.599 --> 00:43:48.599
thomatin -like proteins. These enhancers interact

00:43:48.599 --> 00:43:51.119
with the AFPs and dramatically, exponentially

00:43:51.119 --> 00:43:53.860
increase their thermal hysteresis activity. They

00:43:53.860 --> 00:43:56.519
act as an amplifier. They boost the signal of

00:43:56.519 --> 00:43:59.920
the freeze protection. Exactly. And the biochemical

00:43:59.920 --> 00:44:02.840
machinery involved in this whole process is incredibly,

00:44:03.219 --> 00:44:06.010
unimaginably delicate. Researchers looked closely

00:44:06.010 --> 00:44:08.989
at the dendroids beetle's highly evolved antifreeze

00:44:08.989 --> 00:44:11.750
protein and in the lab they chemically modified

00:44:11.750 --> 00:44:15.989
a single solitary amino acid. arginine. They

00:44:15.989 --> 00:44:17.869
just tweaked one tiny part of the structure.

00:44:18.070 --> 00:44:20.710
That one microscopic modification resulted in

00:44:20.710 --> 00:44:23.329
the complete and total loss of the protein's

00:44:23.329 --> 00:44:25.769
thermal hysteresis ability. It was instantly

00:44:25.769 --> 00:44:28.570
rendered completely useless. It proves how highly

00:44:28.570 --> 00:44:32.190
specific, how unimaginably fine -tuned this evolutionary

00:44:32.190 --> 00:44:34.570
lock -and -key mechanism really is. You change

00:44:34.570 --> 00:44:37.070
one tiny pin in the lock, the whole door just

00:44:37.070 --> 00:44:39.150
flies open to the freezing cold. The beetle dies.

00:44:39.690 --> 00:44:41.849
It's a game of absolute microscopic precision.

00:44:42.059 --> 00:44:44.340
And speaking of fine -tuned mechanisms, I have

00:44:44.340 --> 00:44:46.980
to mention a genuinely mind -bending study from

00:44:46.980 --> 00:44:49.019
2010 that was detailed in our notes, because

00:44:49.019 --> 00:44:51.519
we keep calling them anti -freeze proteins. But

00:44:51.519 --> 00:44:54.000
scientists discovered that AFPs don't just inhibit

00:44:54.000 --> 00:44:57.480
freezing, because they bind so stably, so perfectly

00:44:57.480 --> 00:44:59.619
to the ice matrix, they can actually inhibit

00:44:59.619 --> 00:45:01.840
melting. In a laboratory setting, they were able

00:45:01.840 --> 00:45:05.400
to create superheated water ice crystals. They

00:45:05.400 --> 00:45:08.480
created ice that physically stays solid at temperatures

00:45:08.480 --> 00:45:10.840
where it should technically, thermodynamically,

00:45:11.179 --> 00:45:13.699
be liquid water. Which is a phenomenal physical

00:45:13.699 --> 00:45:16.320
feat. It perfectly illustrates why the scientific

00:45:16.320 --> 00:45:19.079
community is shifting its terminology. These

00:45:19.079 --> 00:45:21.519
proteins are not just simple anti -free solutes.

00:45:21.960 --> 00:45:25.630
They are truly profoundly ice -structuring proteins.

00:45:25.889 --> 00:45:28.530
They actively dictate and manipulate the structural

00:45:28.530 --> 00:45:31.110
integrity of ice in both directions, preventing

00:45:31.110 --> 00:45:33.570
it from forming when it should, and conversely,

00:45:33.849 --> 00:45:35.869
preventing it from dismantling and melting when

00:45:35.869 --> 00:45:39.010
it should. In that concept, the ability to physically

00:45:39.010 --> 00:45:41.550
structure and control ice provides the perfect

00:45:41.550 --> 00:45:44.449
transition to the final major area of our deep

00:45:44.449 --> 00:45:47.010
dive today. Because once humanity discovers a

00:45:47.010 --> 00:45:49.429
biological cheat code as powerful as this, we

00:45:49.429 --> 00:45:51.230
are absolutely without a doubt going to figure

00:45:51.230 --> 00:45:53.179
out how to harness it. First, let's talk about

00:45:53.179 --> 00:45:55.619
that name change. There has been a significant

00:45:55.619 --> 00:45:58.380
PR rebrand in the commercial space. You will

00:45:58.380 --> 00:46:01.039
notice that food scientists and massive corporations

00:46:01.039 --> 00:46:04.980
are pushing hard to rename AFPs to ice -structuring

00:46:04.980 --> 00:46:08.980
proteins, or ISPs. Why? Because when average,

00:46:09.199 --> 00:46:11.800
everyday consumers read the word antifreeze on

00:46:11.800 --> 00:46:14.219
the back of their food packaging, their mind

00:46:14.219 --> 00:46:17.579
immediately, understandably, goes to that toxic,

00:46:17.760 --> 00:46:20.139
neon -essiling glycol in their car radiator.

00:46:20.400 --> 00:46:23.019
Even though the biological proteins and the car

00:46:23.019 --> 00:46:25.760
chemicals have absolutely nothing in common besides

00:46:25.760 --> 00:46:29.099
their end goal of managing ice, the name antifreeze

00:46:29.099 --> 00:46:31.599
is a complete nightmare for marketing. It is

00:46:31.599 --> 00:46:34.079
a very necessary distinction for public understanding

00:46:34.079 --> 00:46:36.900
and commercial acceptance because, as you alluded

00:46:36.900 --> 00:46:39.300
to, the commercial applications of these proteins

00:46:39.300 --> 00:46:41.840
are not some far -off sci -fi future. They're

00:46:41.840 --> 00:46:44.280
already here, right now. So what does this all

00:46:44.280 --> 00:46:46.000
mean for you? You might actually be eating these

00:46:46.000 --> 00:46:48.340
highly evolved ice structuring proteins right

00:46:48.340 --> 00:46:50.960
now. Indeed. The multinational consumer goods

00:46:50.960 --> 00:46:54.019
company Unilever recognized the immense multi

00:46:54.019 --> 00:46:56.460
-billion dollar potential of these ice structuring

00:46:56.460 --> 00:46:58.940
proteins for the global food industry, specifically

00:46:58.940 --> 00:47:01.460
the frozen dessert sector. Years ago, they underwent

00:47:01.460 --> 00:47:03.760
rigorous testing and secured official approval

00:47:03.760 --> 00:47:06.320
across the United States, the UK, the European

00:47:06.320 --> 00:47:09.019
Union, China, Australia, and many other nations

00:47:09.019 --> 00:47:11.920
to use these exact proteins in commercial ice

00:47:11.920 --> 00:47:14.789
cream production. They utilize a highly specific

00:47:14.789 --> 00:47:17.369
genetically modified yeast to safely produce

00:47:17.369 --> 00:47:19.789
the exact same antifreeze proteins originally

00:47:19.789 --> 00:47:22.789
found in those freezing deep sea fish. And they

00:47:22.789 --> 00:47:25.289
put them directly into mass market products like

00:47:25.289 --> 00:47:29.090
popular popsicles and the highly successful Breyers

00:47:29.090 --> 00:47:31.750
light double turned ice cream bars. OK, but taking

00:47:31.750 --> 00:47:35.230
a step back, why? Why on earth does my vanilla

00:47:35.230 --> 00:47:38.409
ice cream need fish antifreeze in it? To solve

00:47:38.409 --> 00:47:40.710
the absolute greatest enemy of the commercial

00:47:40.710 --> 00:47:43.730
ice cream industry. temperature fluctuation.

00:47:44.550 --> 00:47:47.070
Let's trace the journey of ice cream. When it

00:47:47.070 --> 00:47:49.530
is manufactured, it is perfectly smooth. But

00:47:49.530 --> 00:47:51.510
then it has to be transported. It might sit on

00:47:51.510 --> 00:47:53.550
a slightly warm loading dock for 20 minutes.

00:47:53.610 --> 00:47:55.610
It goes into a delivery truck. It goes into the

00:47:55.610 --> 00:47:57.750
grocery store freezer, which goes through defrost

00:47:57.750 --> 00:47:59.590
cycles. Then it goes into your grocery cart as

00:47:59.590 --> 00:48:01.949
you walk around the store. Then it thaws slightly

00:48:01.949 --> 00:48:03.969
on your kitchen counter before you finally put

00:48:03.969 --> 00:48:06.150
it back into your home freezer. During every

00:48:06.150 --> 00:48:08.230
single one of those slate temperature fluctuations,

00:48:08.610 --> 00:48:11.130
the microscopic smooth ice crystals inside the

00:48:11.130 --> 00:48:13.980
ice cream melt slightly and then refreeze. And

00:48:13.980 --> 00:48:16.980
when they refreeze, they undergo that exact same

00:48:16.980 --> 00:48:19.340
recrystallization process we talked about earlier

00:48:19.340 --> 00:48:23.059
with the freeze -tolerant plants and bugs. Thermodynamics

00:48:23.059 --> 00:48:26.579
forces those tiny crystals to fuse into larger,

00:48:26.860 --> 00:48:29.000
jagged, crunchy ice crystals. Which completely

00:48:29.000 --> 00:48:31.960
ruins the texture. It gets that weird icy, crunchy,

00:48:32.199 --> 00:48:34.460
freezer -burnt texture that everyone hates. Exactly.

00:48:34.639 --> 00:48:37.260
But by adding these ice structuring proteins

00:48:37.260 --> 00:48:39.960
into the mix, Unilever completely controls the

00:48:39.960 --> 00:48:42.659
ice crystal growth during those inevitable temperature

00:48:42.659 --> 00:48:44.780
fluctuations. Just like in the freeze tolerant

00:48:44.780 --> 00:48:48.639
organisms, the AFPs bind to the tiny ice crystals

00:48:48.639 --> 00:48:51.000
the moment they start to refreeze, and they physically

00:48:51.000 --> 00:48:53.500
stop them from growing larger. This structural

00:48:53.500 --> 00:48:55.960
control allows Unilever to produce incredibly

00:48:55.960 --> 00:48:59.840
dense, rich creamy and notably reduced fat ice

00:48:59.840 --> 00:49:02.559
cream with far fewer artificial chemical additives

00:49:02.559 --> 00:49:05.059
because the biological protein is doing all the

00:49:05.059 --> 00:49:07.440
heavy lifting of maintaining the smooth microscopic

00:49:07.440 --> 00:49:10.039
texture. It is brilliant engineering. Now whenever

00:49:10.039 --> 00:49:12.219
we mention genetically modified yeast and the

00:49:12.219 --> 00:49:14.539
insertion of fish genes into mass market food,

00:49:14.860 --> 00:49:17.139
it is important that we impartially address the

00:49:17.139 --> 00:49:19.599
concerns noted in our reading. There are anti

00:49:19.599 --> 00:49:22.860
-GMO organizations and consumer advocacy groups

00:49:22.860 --> 00:49:26.429
that have raised concerns suggesting that Introducing

00:49:26.429 --> 00:49:29.710
these novel antifreeze proteins might cause inflammation

00:49:29.710 --> 00:49:32.489
or allergic reactions in humans. It is a concern

00:49:32.489 --> 00:49:34.750
that has been raised publicly, yes. However,

00:49:34.969 --> 00:49:36.869
analyzing the data strictly from an objective,

00:49:37.090 --> 00:49:39.550
toxicological, and historical standpoint, the

00:49:39.550 --> 00:49:42.289
human intake of these specific AFPs in our diet

00:49:42.289 --> 00:49:45.110
is already quite substantial and has been for

00:49:45.110 --> 00:49:48.130
millennia. Historically, humans living in temperate

00:49:48.130 --> 00:49:50.329
and northern regions have consumed these exact

00:49:50.329 --> 00:49:53.389
proteins naturally for centuries. Every single

00:49:53.389 --> 00:49:55.789
time they eat a cold -water fish, winter harvested

00:49:55.789 --> 00:49:58.510
vegetables, or cold tolerant edible mushrooms.

00:49:58.780 --> 00:50:01.119
Based on this extensive history of natural human

00:50:01.119 --> 00:50:03.619
consumption, the overwhelming scientific and

00:50:03.619 --> 00:50:05.679
regulatory consensus is that their functional

00:50:05.679 --> 00:50:08.920
ice binding properties do not impart any toxicological

00:50:08.920 --> 00:50:11.340
or allergenic effects on the human body. And

00:50:11.340 --> 00:50:14.119
as for the transgenic yeast process itself, using

00:50:14.119 --> 00:50:16.480
a modified yeast to brew the protein, the source

00:50:16.480 --> 00:50:18.400
material is very clear that this is standard,

00:50:18.599 --> 00:50:20.480
deeply established practice in the modern food

00:50:20.480 --> 00:50:23.860
and medical industries. This is the exact identical

00:50:23.860 --> 00:50:26.880
biotechnology used to produce modern insulin

00:50:26.880 --> 00:50:29.659
for diabetics. It is the exact same process used

00:50:29.659 --> 00:50:32.179
to produce the rennet that is used to make almost

00:50:32.179 --> 00:50:34.920
all modern mass -produced cheese. You isolate

00:50:34.920 --> 00:50:37.239
the specific gene you want, you insert it into

00:50:37.239 --> 00:50:39.420
a fast -growing yeast, and you let the yeast

00:50:39.420 --> 00:50:43.039
act as a microscopic brewery to safely, cleanly

00:50:43.039 --> 00:50:46.130
produce the protein in massive vats. And from

00:50:46.130 --> 00:50:48.510
an ecological and sustainability standpoint,

00:50:48.829 --> 00:50:52.210
producing it in use is vastly, immeasurably superior.

00:50:52.710 --> 00:50:54.570
It makes industrial production highly efficient

00:50:54.570 --> 00:50:56.650
and more importantly, it absolutely prevents

00:50:56.650 --> 00:50:58.789
the industry from having to harvest and kill

00:50:58.789 --> 00:51:02.309
thousands, if not millions of deep sea fish just

00:51:02.309 --> 00:51:04.630
to extract trace amounts of the protein from

00:51:04.630 --> 00:51:07.590
their blood. It's a win -win. We save the ocean

00:51:07.590 --> 00:51:09.929
ecosystems and we get perfectly smooth ice cream

00:51:09.929 --> 00:51:11.889
that survives the trip home from the grocery

00:51:11.889 --> 00:51:13.969
store. But perfecting the texture of dessert

00:51:13.969 --> 00:51:16.909
is really just the tip of the iceberg, pun fully

00:51:16.909 --> 00:51:19.570
unabashedly intended, because the future commercial

00:51:19.570 --> 00:51:21.510
and medical applications currently being researched

00:51:21.510 --> 00:51:25.090
are massive. We are looking at agricultural revolutions,

00:51:25.409 --> 00:51:27.690
increasing the freeze tolerance of vital crop

00:51:27.690 --> 00:51:30.090
plants to extend harvest seasons and protect

00:51:30.090 --> 00:51:32.809
against devastating sudden frosts, improving

00:51:32.809 --> 00:51:35.170
farm fish production in much colder climates

00:51:35.170 --> 00:51:37.989
to ensure global food security, lengthening the

00:51:37.989 --> 00:51:40.150
shelf life and nutritional integrity of frozen

00:51:40.150 --> 00:51:43.559
foods worldwide. improving the pinpoint precision

00:51:43.559 --> 00:51:46.940
of cryosurgery, where doctors use extreme cold

00:51:46.940 --> 00:51:50.329
to target and destroy cancer cells. The agricultural

00:51:50.329 --> 00:51:52.269
and surgical applications are incredible, but

00:51:52.269 --> 00:51:56.150
then there are the absolute holy grails of cryomedicine.

00:51:56.230 --> 00:51:58.630
We are talking about the ability to dramatically

00:51:58.630 --> 00:52:01.150
enhance the preservation of human organs and

00:52:01.150 --> 00:52:03.469
delicate tissues for transplants. Right now,

00:52:03.489 --> 00:52:05.969
as you may know, the window to transport a donated

00:52:05.969 --> 00:52:08.849
heart or liver is incredibly frustratingly short.

00:52:09.090 --> 00:52:11.610
You cannot freeze a donor organ because the resulting

00:52:11.610 --> 00:52:14.210
ice crystals will immediately rupture the cell

00:52:14.210 --> 00:52:16.409
membranes and destroy the tissue beyond repair.

00:52:16.769 --> 00:52:19.519
If we can master the use of synthesized AFPs

00:52:19.519 --> 00:52:22.139
to safely freeze, transport, and then flawlessly

00:52:22.139 --> 00:52:24.639
thaw human organs without cellular damage, it

00:52:24.639 --> 00:52:27.000
would fundamentally revolutionize global transplant

00:52:27.000 --> 00:52:29.320
medicine. Beyond that, there is active research

00:52:29.320 --> 00:52:31.920
into advanced therapies for severe hypothermia

00:52:31.920 --> 00:52:34.960
and potentially the ultimate most ambitious frontier

00:52:34.960 --> 00:52:38.440
of all, human cryopreservation, often referred

00:52:38.440 --> 00:52:41.519
to as cryonics. The theoretical ability to safely

00:52:41.519 --> 00:52:45.019
freeze an entire human body, halt all biological

00:52:45.019 --> 00:52:48.000
degradation, and revive it decades or centuries

00:52:48.000 --> 00:52:50.480
later. without massive, irreversible cellular

00:52:50.480 --> 00:52:52.659
damage. It sounds like pure science fiction,

00:52:52.880 --> 00:52:55.340
the stuff of space operas and futuristic movies,

00:52:55.679 --> 00:52:59.079
but the biological blueprint, the exact molecular

00:52:59.079 --> 00:53:01.219
mechanism to make it happen, already exists.

00:53:01.400 --> 00:53:04.139
It has been perfected. It is floating right now

00:53:04.139 --> 00:53:06.519
in the blood of an Antarctic fish and the hemolymph

00:53:06.519 --> 00:53:09.539
of an Alaskan beetle. To quickly recap the incredible

00:53:09.539 --> 00:53:11.400
mind -expanding journey we've been on today,

00:53:12.000 --> 00:53:14.079
we started with deep sea drilling cores revealing

00:53:14.079 --> 00:53:17.039
a 30 million year old climate catastrophe, a

00:53:17.039 --> 00:53:19.300
mass extinction that forcefully pushed surviving

00:53:19.300 --> 00:53:22.199
fish to blindly evolve their own digestive enzymes

00:53:22.199 --> 00:53:24.840
into a biological antifreeze. We learned about

00:53:24.840 --> 00:53:27.039
smelt pulling off an impossible evolutionary

00:53:27.039 --> 00:53:29.800
heist to steal survival DNA directly from herring.

00:53:30.119 --> 00:53:32.980
We scaled all the way down to microscopic diatoms

00:53:32.980 --> 00:53:35.699
and edible fungi surviving the brutal sea ice.

00:53:35.880 --> 00:53:38.260
And we looked at heavily armored bugs that can

00:53:38.260 --> 00:53:41.039
comfortably, casually survive negative 30 degrees

00:53:41.039 --> 00:53:43.920
Celsius. We decoded the complex microscopic zipper

00:53:43.920 --> 00:53:46.420
mechanisms and hydrophobic forces that physically

00:53:46.420 --> 00:53:49.639
locked down expanding ice crystals. And finally,

00:53:50.059 --> 00:53:52.400
We traced how all of this ancient evolutionary

00:53:52.400 --> 00:53:55.000
brilliance has been captured by modern biotechnology

00:53:55.000 --> 00:53:57.980
to keep your Breyers ice cream perfectly smooth.

00:53:58.300 --> 00:54:00.800
It is a profound, humbling demonstration of nature's

00:54:00.800 --> 00:54:03.659
relentless adaptability. But there is one final,

00:54:03.960 --> 00:54:05.760
entirely unmentioned thread to pull from our

00:54:05.760 --> 00:54:07.099
source material that I want to leave you with

00:54:07.099 --> 00:54:10.179
today. Up until very recently, we were entirely

00:54:10.179 --> 00:54:13.119
dependent on biological sources. But in 2021,

00:54:13.480 --> 00:54:15.599
a breakthrough occurred. Scientists at the E

00:54:15.599 --> 00:54:17.519
.P. Schofell in Switzerland and the University

00:54:17.519 --> 00:54:20.619
of Warwick successfully created an entirely artificial

00:54:20.619 --> 00:54:22.960
imitation of antifreeze proteins in the lab.

00:54:23.239 --> 00:54:25.579
We are no longer strictly reliant on harvesting

00:54:25.579 --> 00:54:28.599
or brewing nature's designs. Human science can

00:54:28.599 --> 00:54:30.980
now actively synthesize these ice structuring

00:54:30.980 --> 00:54:33.940
mechanisms from scratch. Furthermore, consider

00:54:33.940 --> 00:54:36.219
the Alaskan beetle we discussed, the one that

00:54:36.219 --> 00:54:39.480
completely bypassed proteins and uses a non -protein

00:54:39.480 --> 00:54:42.639
sugar polymer, xylomanin, to easily survive the

00:54:42.639 --> 00:54:45.360
freezing tundra. This convergence of synthetic

00:54:45.360 --> 00:54:48.500
biology and non -protein cryoprotectants raises

00:54:48.500 --> 00:54:51.500
a highly provocative question. If humans can

00:54:51.500 --> 00:54:54.039
now artificially synthesize these complex ice

00:54:54.039 --> 00:54:56.280
structuring mechanisms, and if nature has already

00:54:56.280 --> 00:54:58.199
proven that you don't even need complex fragile

00:54:58.199 --> 00:55:00.539
proteins to do it, what does this mean for the

00:55:00.539 --> 00:55:03.440
future of human space exploration? Could we synthetically

00:55:03.440 --> 00:55:06.159
adapt human biology or perhaps the delicate crops

00:55:06.159 --> 00:55:08.840
we need to sustain us to comfortably survive

00:55:08.840 --> 00:55:11.179
the deeply frozen hostile environments of Mars

00:55:11.179 --> 00:55:13.920
or the icy radiation blasted moons of Jupiter

00:55:13.920 --> 00:55:17.280
like Europa? Could an artificial mass synthesized

00:55:17.280 --> 00:55:20.119
xylomanon be the key biological shield that eventually

00:55:20.119 --> 00:55:22.780
protects the first human colonists from the lethal

00:55:22.780 --> 00:55:25.940
sub -zero vacuum of deep space? That is an incredible

00:55:25.940 --> 00:55:28.829
profound thought to end on. from a small fish

00:55:28.829 --> 00:55:31.530
swimming in the dark freezing waters of an ancient

00:55:31.530 --> 00:55:34.510
Antarctica to the very real potential for human

00:55:34.510 --> 00:55:36.769
survival on the frozen surface of another planet.

00:55:37.510 --> 00:55:39.530
Thank you so much for joining us on this deep

00:55:39.530 --> 00:55:41.329
dive. I guarantee you are going to look at the

00:55:41.329 --> 00:55:43.530
winter frost on your window and your next bowl

00:55:43.530 --> 00:55:45.889
of vanilla ice cream in a completely different

00:55:45.889 --> 00:55:46.150
light.