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EP: Extraterrestrische Physik

EP 14: Leben und Lebensbedingungen ausserhalb der Erde II

EP 14.8: Vortrag

Mittwoch, 22. März 2000, 17:30–17:45, N3110

Molecular Phylogeny of Vertebrate Brain Gangliosides in Adaptation to Life under Extreme Temperatures — •Hinrich Rahmann — Zoological Institute, University of Hohenheim, D-70593 Stuttgart, Germany

The synaptic terminals within the nervous system of vertebrates were found to be the most thermo-sensitive structures of the whole organism. They show significant functional changes in adaptation to alterations in the environmental temperature. On this background, charged sialo-glycosphingolipids (= gangliosides) being highly concentrated particularly in the synaptic terminals, according to quite unusual physico-chemical properties became favourite candidates to play the essential role in the process of thermal adaptation of neuronal activities (transmission and storage of information. The biochemical data presented reveal that the brain ganglioside composition of vertebrates being adapted to life under extreme temperatures (cold-blooded fishes living in the tropics or in antarctica and warm-blooded mammals during their early development or hibernation) adapts according to the rule: “The lower the environmental temperature the more polar is the composition (polarity) of brain gangliosides”. These in vivo-results can be corralated with additional physico-chemical data obtained with artificial mono- and bilayer model systems demonstrating a peculiar thermosensitivity of the surface behaviour of neuronal gangliosides with the consequence to maintain homeoviscosity in areas surrounding functional membraneous proteins (ion channels, receptors etc.) independent from the environmental temperature.