Temperature extremes. Cold Dangers of ice formation

1. Temperature extremes. • Cold • Dangers of ice formation • How poikilotherms deal with sub-zero temperatures • Hot—the heat-shock response

2. Figure 9.22 Barnacles encased in ice during low tide along a northern seacoast

3. This process of crystal formation can be devastating tocells in two ways. 1. Formation of large crystals can disrupt cell structure and membraneintegrity. http://www.asymptote.co.uk/gallery/Videos/Eggs%201.mov

4. Ice front 2. Ice formationaround cells candraw out water, causingsevere dehydrationand shrinkage of thecell contents. Microsterias rotata (unicellular green alga)

5. Figure 9.23 The process of extracellular freezing in a tissue

6. All of these species live in sub-zero environments for part of the year; but surviveby different mechanisms. Epiblema scudderiana (caterpillar) Eurosta solidaginis (fly) Rana sylvatica (wood frog) Honeybee Box turtles, largest known freeze-tolerant animals. Painted turtles

7. Five ways that animals deal with below zero temperatures. 1. Heat the house 2. Get out of town 3. Spend the winter as a simple stage, usually as an egg. 4. Freeze avoidance 5. Freeze tolerance. Ken Storey

8. Bee swarm structure as a function ofexternal temperature. 9 C 1 C 29 C Heinrich 1981

9. Externaltemperature5C Externaltemperature30C Heinrich 1981

10. Temperature around brood in hive isremarkably well regulated. Ambient T = 3C 25C

11. Five ways that animals deal with below zero temperatures. 1. Heat the house 2. Get out of town 3. Spend the winter as a simple stage, usually as an egg. 4. Freeze avoidance 5. Freeze tolerance.

12. Milkweed Monarch Winter cluster in Mexico

13. Another way to ‘leave’ town: hide under an insulating blanket of snow.

14. Five ways that animals deal with below zero temperatures. 1. Heat the house 2. Get out of town 3. Spend the winter as a simple stage, usually as an egg. 4. Freeze avoidance 5. Freeze tolerance.

15. Five ways that animals deal with below zero temperatures. 1. Heat the house 2. Get out of town 3. Spend the winter as a simple stage, usually as an egg. 4. Freeze avoidance 5. Freeze tolerance.

16. Epiblema scudderiana(moth) Eurosta solidaginis (fly)

17. Female Eurosta Female ovipositing inSolidago bud Goldenrod (Solidago)

18. Wintergall Gall in late summerSolidago Parasitic wasp thatsticks eggs into gall chamber

19. Problem: both species live in northern areas, in galls that get very coldduring the winter (- 20 to -30°C). How do they survive? • Epiblema is freeze avoiding • Eurosta is freeze tolerant • These two strategies are quite different, but involve some of the samebiochemical mechanisms.

20. Freeze avoidance Gall temperature Supercooling point oflarvae

21. Super cooling of aqueous fluids

22. Heat of crystallization Trace of water temperature in a straw that was gradually cooled. Ice didn’t form spontaneously until about -15°C.

23. This graph shows a frequency histogram of ice nucleation temperaturesfor pure water in a small straw cooled at about 0.3°C per minute. Supercoolingis easiest insmall volumesof water—whichis what insectsare: insectsnaturally supercoolto about -10°C

24. Polyhydric alcohols carbon hydrogen oxygen Ethanol (notused as a cryoprotectant) Glycerol (commoncryoprotectant) Ethylene glycol (the antifreezein your car’sradiator). How to depress the supercooling point as much as possible? • Increase the solute concentration, usually by using small polyhydric alcohols (e.g., glycerol, sorbitol) • Use proteins that inhibit the formation of ice crystals. • Avoid contact with ice that can seed further ice formation.

25. 3 M glycerol! Epiblema scudderiana In mid-winter, glycerolcan make up 20 – 25% ofthe insect’s total body mass. The glycerol is manufacturedfrom large stores of glycogen.

26. A January 2010 article in Journal of Experimental Biology Deep supercooling, vitrification and limited survival to –100°C in the Alaskan beetle Cucujus clavipes puniceus(Coleoptera: Cucujidae) larvae T. Sformo1,*, K. Walters2, K. Jeannet1, B. Wowk3, G. M. Fahy3, B. M. Barnes1 and J. G. Duman2

27. Another solution: make antifreeze proteins. These proteins bindto small ice crystals and prevent them from growing.

28. Freezing points of aqueous solutions containing major sugars, salts and glycoproteins used as antifreeze agents. These glyco-proteins fromAntarctic fish.

29. Liou et al. 2000 Structure of antifreeze protein from Tenebrio molitor (mealworm beetle)

30. AFP Ice The AFP is structured sothat it fits exactly into the 2-D structure of the ice lattice (probably by hydrophobicinteractions). Liou et al. 2000