Cryoprotectants are metabolic fuels during long term frost exposure in the earthworm Dendrobaena octaedra .
Ectothermic animals that live in the subarctic and temperate regions must have strategies to deal with periods of frost during winter. The earthworm Dendrobaena octaedra is a freeze tolerant species that accumulates large concentrations of the cryoprotectant glucose upon ice formation in the extrace...
| Published in: | Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology |
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| Main Authors: | , , , |
| Format: | Conference Object |
| Language: | English |
| Published: |
2008
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| Subjects: | |
| Online Access: | https://pure.au.dk/portal/da/publications/cryoprotectants-are-metabolic-fuels-during-long-term-frost-exposure-in-the-earthworm-dendrobaena-octaedra(117d89c0-033a-11de-a987-000ea68e967b).html https://doi.org/10.1016/j.cbpa.2008.04.414 https://pure.au.dk/ws/files/15366234/AbstractSEB.pdf |
| Summary: | Ectothermic animals that live in the subarctic and temperate regions must have strategies to deal with periods of frost during winter. The earthworm Dendrobaena octaedra is a freeze tolerant species that accumulates large concentrations of the cryoprotectant glucose upon ice formation in the extracellular fluid. This study investigates if D. octaedra metabolizes its primary cryoprotectant as an energy source when frozen for longer periods. In this study D. octaedra were exposed to frost at 2 °C for 47 days. The results clearly demonstrate a gradual decrease in the level of glucose and simultaneously an accumulation of lactate, alanine and succinate as a result of the continuous anaerobic metabolism. Freeze mortality (~ 30%) did not increase with time suggesting that the accumulation of waste products were not toxic to the worms. Instead dead worms were always characterised by low glucose and glycogen levels indicating that depletion of fermentable resources was the primary cause of death. Calorimetric measurements of metabolic rate showed a 15-fold metabolic depression in frozen versus unfrozen worms and this reduction in metabolic rate is clearly of importance for long term survival of frozen worms. On the basis of metabolic rate measurements we calculated that the “average” worms would be able to survive for a total of 83 days before the glucose storage becomes exhausted. In conclusion, the present study suggests that the large accumulations of glucose during frost may be more important as anaerobic fuel source than as a cryoprotectant. |
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