Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS
NOVA ScienceNOW

Frozen Frogs

  • Posted 04.01.05
  • NOVA scienceNOW

Wood frogs freeze solid in winter then thaw back to life and mate in the spring. How do they do it? Scientists have now figured out how to recreate this extraordinary process of cryopreservation with mammalian organs. To date they have successfully frozen, thawed, and transplanted rat livers and pig hearts. Their dream? Enhanced preservation of human organs for transplant.

Close
Launch Video Running Time: 04:00

Transcript

FROZEN FROGS

PBS Airdate: April 1, 2005

ROBERT KRULWICH: Well, as we all know, it is finally springtime. So before we go, I wanted to celebrate the season. And I can think of no better way than to introduce you to a creature who is, again, very, very small, and lives down here somewhere, close to the ground, doing things that I think you will find very surprising.

Here's the thing about North American wood frogs. They're small...

JOHN COSTANZO: So it might be difficult to spot a frog.

ROBERT KRULWICH: ...very small. But they're everywhere, just out of view, hiding on the forest floor.

JOHN COSTANZO: He's camouflaged. His coloration is the same as the soil around him. You see him here? He's cold.

ROBERT KRULWICH: You can find them here in southern Ohio, all the way up to the Arctic Circle. But, wherever they are, once it gets cold, with the first sprinkle of ice, this frog does something I didn't know was possible. As soon as the frog touches, just touches, an ice crystal...

JOHN COSTANZO: This animal is going to freeze.

ROBERT KRULWICH: Freeze, freeze?

JOHN COSTANZO: Freeze solid, freeze.

ROBERT KRULWICH: That touch of ice immediately sets off signals inside the frog, says Professor John Costanza, that pull water away from the center of its body. So the frog's internal organs are now wrapped in a puddle of water that then turns to solid ice.

JOHN COSTANZO: I still can't get over it. It's really an amazing, amazing thing.

ROBERT KRULWICH: There is no breathing, no kidney function, the heart stops.

JOHN COSTANZO: And there will be no heartbeat for a long period of time.

ROBERT KRULWICH: You mean as in no heartbeat? Nothing?

JOHN COSTANZO: Right. Flat line.

ROBERT KRULWICH: Flatline. For an hour or two?

JOHN COSTANZO: It could be for days, perhaps even weeks.

ROBERT KRULWICH: Really? Sounds like it's virtually dead, no?

JOHN COSTANZO: We know that the frog isn't dead, but he's probably about as close as you can get.

ROBERT KRULWICH: To being dead?

JOHN COSTANZO: Yes.

ROBERT KRULWICH: So, from the outside, this little frog feels like a rock except that as it froze, the frog flooded itself with a kind of sugar.

JOHN COSTANZO: The frog's blood sugar is distributed through the circulatory system and works like an antifreeze.

ROBERT KRULWICH: It's harder for water to freeze, so cells stay just damp enough for the animal to hold itself together, until the springtime, when the days grow a little longer and the ground gets a little warmer and then, well, a kind of miracle happens.

After weeks or months of no heartbeat, none, suddenly there's a pulse. And that first heartbeat leads to another and then another and then, within a day, and—in the case of this little frog, it took about 10 hours—the animal literally comes back to life.

JOHN COSTANZO: Spontaneous resumption of function.

ROBERT KRULWICH: Why?

JOHN COSTANZO: We don't know. We don't know what triggers that event.

ROBERT KRULWICH: And think how elegant a business this is, because although the sun is warming up the outside of this little guy, somehow his insides, his heart, his brain, they thaw first. His insides warm up before his outsides. But somehow, it all happens in perfect synchrony every spring.

JOHN COSTANZO: Yes, and it's going to undertake a very energetic activity. It's mating time.

ROBERT KRULWICH: Oh, you mean hours after it thaws it's going to do it with a lady?

JOHN COSTANZO: It's going to perform.

ROBERT KRULWICH: Uh-huh. What an animal!

JOHN COSTANZO: Can we say that on TV?

ROBERT KRULWICH: I don't know if we can or not.

Well, we just did.

Credits

Frozen Frogs

Produced and Edited by
Vincent Liota & Win Rosenfeld

NOVA scienceNOW

Executive Producer
Samuel Fine
Executive Editor
Robert Krulwich
Senior Series Producer
Vincent Liota
Supervising Producer
Andrea Cross
Development Producer
Kyla Dunn
Associate Producer
Win Rosenfeld
Program Editor
David Small
Unit Manager
Candace White
Researcher
Jason Spingarn-Koff
Production Secretary
Hong Jung
Music
Rob Morsberger
NOVA scienceNOW Series Animation
Edgeworx
Associate Producers
Anthony Manupelli
Mary Robertson
Cass Sapir
Ben Sweeney
Camera
Nate Clapp
Brian Dowley
Allen Facemire
Ken Fuhr
Bob Hanna
Jack Rayzor
Jon Tichota
Joe Vitagliano
Brett Wiley
Ken Willanger
Sound Recordists
Bob Bryan
Walter James
Anthony Rowland
Jayme Roy
George Schafnacker
Jimmy Williams
Andrew Yuncza
Audio Mix
John Jenkins
Animation
Pie Design
Additional Production by
Simon Nasht
Annamaria Talas
Additional Music
Mark De Gli Antoni
Production Assistant
Robbie Gemmel
Compositing
Yunsik Noh
Special Thanks
American Museum of Natural History
Jade Boyd
Florida State University
R. Thomas Hammond
Ann Kiessling
David Scadden
Special thanks for its decade of support for NOVA to the
Park Foundation
Howard Hughes Medical Institute Investigators
Doug Melton
Leonard Zon
Archival Material
ABCNEWS VideoSource
Rainer Albiez
Avalanche, Inc.
BBC Motion Gallery
Dr. Tony Brain & David Parker / Photo Researchers, Inc
Corbis Corporation
The Field Museum of Chicago
Gillian Darling
Susan A. Levine Photographic Art
Lubbock Metro
National Geographic Film Library
Dr. Yorgus Nikas/Photo Researchers Inc.
Bill Nipper
Paprikaas Animation Studios - Les Films D'ici, France
Popular Science
Small Times Media
Ultimate Ungulate Images
NOVA Series Graphics
yU + co.
NOVA Theme MUSIC
Walter Werzowa
John Luker
Musikvergnuegen, Inc.
Additional NOVA Theme Music
Ray Loring
Post Production Online Editor
Spencer Gentry
Closed Captioning
The Caption Center
NOVA Administrator
Dara Bourne
Publicity
Jonathan Renes
Diane Buxton
Olivia Wong
Senior Researcher
Barbara Moran
Production Coordinator
Linda Callahan
Unit Manager
Lola Norman-Salako
Legal Counsel
Susan Rosen Shishko
Post Production Assistant
Patrick Carey
Associate Producer, Post Production
Nathan Gunner
Post Production Supervisor
Regina O'Toole
Post Production Editor
Rebecca Nieto
Post Production Manager
Maureen Barden Lynch
Supervising Producer
Stephen Sweigart
Producer, Special Projects
Susanne Simpson
Coordinating Producer
Laurie Cahalane
Senior Science Editor
Evan Hadingham
Senior Series Producer
Melanie Wallace
Managing Director
Alan Ritsko
Senior Executive Producer
Paula S. Apsell

NOVA scienceNOW is a trademark of the WGBH Educational Foundation

This material is based upon work supported by the National Science Foundation under Grant No. 0229297.  Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

© 2005 WGBH Educational Foundation

All rights reserved

Image credit: (wood frog) © Stephen Maka Photography

Related Links

  • Cold Cures

    The inner workings of frozen frogs offer insight into the medical uses of extreme cold.

  • Frozen Frogs: Expert Q&A

    Miami University researcher Jon Costanzo answers questions about reptile and amphibian cryobiology.

  • Profile: Mark Siddall

    Meet Mark Siddall, a leech expert and chef of exotic food.

  • Marathon Mouse

    With an "exercise pill," researchers turn couch-potato rodents into champion runners.

  • Fish Surgery

    Pet owners are turning to veterinary medicine for costly treatments of their goldfish, koi, and other fish.

  • Frozen Frogs

    Discover how the wood frog freezes solid every winter, an adaptation that allows the organism to survive the season.