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  • 1
    Electronic Resource
    Electronic Resource
    Post-freeze recovery of peripheral nerve function in the freeze-tolerant wood frog, Rana sylvatica (1994)
    Springer
    Journal of comparative physiology 164 (1994), S. 316-320 
    Details
    ISSN: 1432-136X
    Keywords: Freeze tolerance ; Sciatic nerve ; Osmotic stress ; Cryoprotection ; Frog, Rana sylvatica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We investigated the restoration of peripheral nerve function and simple neurobehavioral reflexes in the freeze-tolerant wood frog (Rana sylvatica). Thirty-two specimens, allowed to freeze for 39 h and ultimately cooled to-2.2°C, were sampled at various time intervals up to 60 h after thawing at 5°C was initiated. The sciatic nerves of treated frogs were initially unresponsive to stimulation, but usually regained excitability within 5 h. Except for a slight reduction in nerve excitability characteristics of the compound action potentials of treated frogs were indistinguishable from those of control frogs. Recovery times for the hindlimb retraction and righting reflexes were 8 h and 14 h, respectively. Concentrations of the cryoprotectant glucose increased 8.2-fold in the sciatic nerve and 10.5-fold in the underlying semimembranosis muscle of treated frogs, and remained elevated for at least 60 h after thawing was initiated. These organs lost 47.2% and 15.9%, respectively, of their water during freezing, but were rehydrated within 2 h of the onset of thawing. The accumulation of glucose and the withdrawal of tissue water apparently are cryoprotective responses which enable this species to survive freezing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00346449
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  • 2
    Electronic Resource
    Electronic Resource
    Cryoprotective and osmotic responses to cold acclimation and freezing in freeze-tolerant and freeze-intolerant earthworms (1999)
    Springer
    Journal of comparative physiology 169 (1999), S. 207-214 
    Details
    ISSN: 1432-136X
    Keywords: Key words Freeze tolerance ; Earthworms ; Eisenia nordenskioeldi ; Cryoprotectants ; Glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In this paper we present the results of physiological responses to winter acclimation and tissue freezing in a freeze-tolerant Siberian earthworm, Eisenia nordenskioeldi, and two freeze-intolerant, temperate earthworm species, Lumbricus rubellus and Aporrectodea caliginosa. By analysing the physiological responses to freezing of both types we sought to identify some key factors promoting freeze tolerance in earthworms. Winter acclimation was followed by a significant increase in osmolality of body fluids in E. nordenskioeldi, from 197 mosmol kg−1 in 10 °C-acclimated animals to 365 mosmol kg−1 in animals acclimated to 0 °C. Cold acclimation did not cause any change in body fluid osmolality in the two freeze-intolerant species. As a response to ice formation in the body, the freeze-intolerant species produced copious amounts of slime and expulsion of coelomic fluids, and thereby lost 10–30% of their total water content. Contrary to this, the freeze-tolerant species did not lose water upon freezing. At temperatures down to −6.5 °C, the ice content in the freeze-tolerant E. nordenskioeldi was significantly lower than in L. rubellus. At lower temperatures there were no differences in ice content between the two species. Cold acclimated, but unfrozen, specimens of all three species had low levels of ammonia, urea, lactate, glycerol and glucose. As a response to ice formation, glucose levels significantly increased within the first 24 h of freezing. This was most pronounced in E. nordenskioeldi where a 153-fold increase of glucose was seen (94 mmol · l−1). In L. rubellus and A. caliginosa a 19-fold and 17-fold increase in glucose was seen. This is the first study on physiological mechanisms promoting freeze tolerance in E. nordenskioeldi, or any other oligochaete. Our results suggest that the cryoprotective system of this species more closely resembles that of freeze-tolerant anurans, which synthesize cryoprotectants only after tissues begin to freeze, than that of cold-hardy invertebrates which exhibit a preparatory accumulation of cryoprotectants during seasonal exposure to low temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003600050213
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of soil hydric parameters on the winter cold hardiness of a burrowing beetle, Leptinotarsa decemlineata (Say) (1997)
    Springer
    Journal of comparative physiology 167 (1997), S. 169-176 
    Details
    ISSN: 1432-136X
    Keywords: Key words  Cold hardiness  ;  Inoculative freezing  ;   Insect overwintering  ;  Microenvironment  ; Moisture relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This investigation examined the influence of soil moisture and associated parameters on the cold hardiness of the Colorado potato beetle (Leptinotarsa decemlineata Say), a temperate-zone species that overwinters in terrestrial burrows. The body mass and water content of adult beetles kept in sand at 4 °C varied over a 16-week period of diapause according to the substratum's moisture content. Changes in body water content, in turn, influenced the crystallization temperature (range −3.3 to −18.4 °C; n = 417), indicating that environmental moisture indirectly determined supercooling capacity, a measure of physiological cold hardiness. Beetles held in dry sand readily tolerated a 24-h exposure to temperatures ranging from 0° to −5 °C, but those chilled in sand containing as little as 1.7% water (dry mass) had elevated mortality. Thus, burrowing in dry soils not only promotes supercooling via its effect on water balance, but may also inhibit inoculative freezing. Mortality of beetles exposed to −5 °C for 24 h was lower in substrates composed of sand, clay and/or peat (36–52%) than in pure silica sand (78%) having an identical water content (17.0% dry mass). In addition to moisture, the texture, structure, water potential, and other physico-chemical attributes of soil may strongly influence the cold hardiness and overwintering survival of burrowing insects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003600050061
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  • 4
    Electronic Resource
    Electronic Resource
    Supercooling, ice inoculation and freeze tolerance in the European common lizard, Lacerta vivipara (1995)
    Springer
    Journal of comparative physiology 165 (1995), S. 238-244 
    Details
    ISSN: 1432-136X
    Keywords: Freeze tolerance ; Supercooling ; Cold-hardiness ; Cryoprotection ; Lizard ; Lacerta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The European common lizard (Lacerta vivipara) is widely distributed throughout Eurasia and is one of the few Palaearctic reptiles occurring above the Arctic Circle. We investigated the cold-hardiness of L. vivipara from France which routinely encounter subzero temperatures within their shallow hibernation burrows. In the laboratory, cold-acclimated lizards exposed to subfreezing temperatures as low as -3.5°C could remain unfrozen (supercooled) for at least 3 weeks so long as their microenvironment was dry. In contrast, specimens cooled in contact with ambient ice crystals began to freeze within several hours. However, such susceptibility to inoculative freezing was not necessarily deleterious since L. vivipara readily tolerated the freezing of its tissues, with body surface temperatures as low as -3.0°C during trials lasting up to 3 days. Freezing survival was promoted by relatively low post-nucleation cooling rates (≤0.1°C·h-1) and apparently was associated with an accumulation of the putative cryoprotectant, glucose. The cold-hardiness strategy of L. vivipara may depend on both supercooling and freeze tolerance capacities, since this combination would afford the greatest likelihood of surviving winter in its dynamic thermal and hydric microenvironment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00260815
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  • 5
    Electronic Resource
    Electronic Resource
    Electrophysiological and ultrastructural correlates of cryoinjury in sciatic nerve of the freeze-tolerant wood frog, Rana sylvatica (1999)
    Springer
    Journal of comparative physiology 169 (1999), S. 351-359 
    Details
    ISSN: 1432-136X
    Keywords: Key words Freeze tolerance ; Sciatic nerve ; Cryoinjury ; Dehydration ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We investigated function and ultrastructure of sciatic nerves isolated from wood frogs (Rana sylvatica) endemic to the Northwest Territories, Canada, following freezing at −2.5 °C, −5.0 °C, or −7.5 °C. All frogs frozen at −2.5 °C, and most frogs (71%) frozen at −5.0 °C, recovered within 14 h after thawing began; however, frogs did not survive exposure to −7.5 °C. Sciatic nerves isolated from frogs frozen at −7.5 °C were refractory to electrical stimulation, whereas those obtained from frogs surviving exposure to −2.5 °C or −5.0 °C generally exhibited normal characteristics of compound action potentials. Frogs responded to freezing by mobilizing hepatic glycogen reserves to synthesize the cryoprotectant glucose, which increased 20-fold in the liver and 40-fold in the blood. Ultrastructural analyses of nerves harvested from frogs in each treatment group revealed that freezing at −2.5 °C or −5.0 °C had little or no effect on tissue and cellular organization, but that (lethal) exposure to −7.5 °C resulted in marked shrinkage of the axon, degeneration of mitochondria within the axoplasm, and extensive delamination of myelin sheaths of the surrounding Schwann cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003600050231
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