Related Experiment Videos
Cryoprotection by urea in a terrestrially hibernating frog
Jon P Costanzo1, Richard E Lee
1Department of Zoology, Miami University, Oxford, OH 45056, USA. costanjp@muohio.edu
The Journal of Experimental Biology
|October 26, 2005
Summary
Urea, a known osmolyte, is crucial for wood frog (Rana sylvatica) freezing tolerance. This cryoprotectant protects against freeze-thaw damage in hibernating amphibians.
Area of Science:
- Zoology
- Biochemistry
- Ecology
Background:
- Urea is recognized for its role as an osmolyte in osmotic adaptation.
- This study investigates the lesser-known functions of urea in diverse taxa, specifically focusing on freezing tolerance.
Purpose of the Study:
- To determine the role of urea in the freezing tolerance of the wood frog (Rana sylvatica).
- To assess urea's efficacy as a cryoprotectant in amphibian tissues.
Main Methods:
- Monitoring urea accumulation in wood frogs under natural conditions.
- Laboratory experiments to assess urea's cryoprotective effects on erythrocytes and tissues.
- Measuring lysis and lactate dehydrogenase (LDH) leakage as indicators of cell damage.
Main Results:
- Wood frogs accumulate significant urea levels during autumn and early winter.
- Urea demonstrated cryoprotective properties comparable to glycerol and glucose.
- Urea treatment improved the viability of frozen amphibian tissues.
Conclusions:
- Urea plays a vital, previously unrecognized role in the freezing tolerance of wood frogs.
- Urea functions as both an osmoprotectant and a cryoprotectant in hibernating amphibians.
- Findings suggest urea is essential for terrestrial hibernation survival in freezing environments.