Katarina Hedlund. Foto.

Katarina Hedlund

Professor

Katarina Hedlund. Foto.

Seasonal changes in lipid composition and glycogen storage associated with freeze-tolerance of the earthworm, Dendrobaena octaedra

Författare

  • Johannes Overgaard
  • Michaela Tollarova
  • Katarina Hedlund
  • Soren O. Petersen
  • Martin Holmstrup

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.

Ämne

  • Ecology

Nyckelord

  • Winter
  • temperatures
  • Membrane lipids
  • Freeze-tolerance
  • Glycogen
  • Earthworms

Status

Published

Forskningsgrupp

  • Soil Ecology

ISBN/ISSN/Övrigt

  • ISSN: 0174-1578