Katarina Hedlund
Professor
Seasonal changes in lipid composition and glycogen storage associated with freeze-tolerance of the earthworm, Dendrobaena octaedra
Författare
Summary, in English
The earthworm, Dendrobaena octaedra, is a common species in the uppermost soil and humus layers of coniferous forests and tundra in temperate and subarctic regions. The species is freeze-tolerant and may survive several months in a frozen state. Upon freezing, glycogen reserves are rapidly converted to glucose serving as a cryoprotectant and fuel for metabolism. In the present study we investigated the induction of freeze-tolerance under field conditions, and sought to find relationships between temperature, glycogen and fat reserves, membrane phospholipid composition and the degree of freeze-tolerance. Freeze-tolerance was induced when worms had experienced temperatures below 5A degrees C for 2 weeks or more. Freeze-tolerance was linked to the magnitude of glycogen reserves, which also fluctuated with field temperatures being highest in autumn and winter. On the other hand fat reserves seemed not to be linked with freeze-tolerance at all. However, high glycogen alone did not confer freeze-tolerance; alterations in the membrane phospholipid fatty acid composition (PLFA) were also necessary in order to secure freeze-tolerance. The changes in PLFA composition were generally similar to changes occurring in other ectothermic animals during winter acclimation with an increased degree of unsaturation of the PLFAs.
Avdelning/ar
- Biodiversitet
- Markgruppen
Publiceringsår
2009
Språk
Engelska
Sidor
569-577
Publikation/Tidskrift/Serie
Journal of Comparative Physiology B
Volym
179
Issue
5
Dokumenttyp
Artikel i tidskrift
Förlag
Springer
Ämne
- Ecology
Nyckelord
- Winter
- temperatures
- Membrane lipids
- Freeze-tolerance
- Glycogen
- Earthworms
Status
Published
Forskningsgrupp
- Soil Ecology
ISBN/ISSN/Övrigt
- ISSN: 0174-1578