Changes in brain ganglioside composition of normothermic and hibernating golden hamsters (Mesocricetus auratus).

1. Brain ganglioside patterns of normothermic and hibernating golden hamsters (Mesocricetus auratus) and laboratory mice had been investigated. 2. The ganglioside pattern of normothermic golden hamsters in comparison to that of mice is characterized by an unusual high amount of the polar trisialoganglioside GT1. 3. In the hibernating golden hamster in contrast to normothermic counterparts the brain gangliosides are more polar (polysialization-effect). 4. The results are discussed with regard to the hypothesis that neuronal membranes provided with more polar gangliosides at lower environmental temperatures might be more efficient with respect to the high complexation ability of gangliosides with Ca2+-ions.     

Variability in brain ganglioside content and composition of endothermic mammals, heterothermic hibernators and ectothermic fishes

Content and composition of brain gangliosides were compared among endothermic mammals, heterothermic hibernators and ectothermic fishes from habitats with extreme ambient temperatures (tropic vs. antarctic waters). In general the content of brain gangliosides in fishes is significantly lower and exhibits a greater variability than in mammals. The composition of brain gangliosides was investigated using both one- and two-dimensional High Performance Thin Layer Chromatography (HPTLC). Both techniques showed a remarkable increase in the number of individual ganglioside fractions and an additional increase of higher polar fractions in fishes as compared with mammals. The 2D-HPTLC revealed a significant decrease in the relative proportion of alkali-labile gangliosides in the course of evolution from fish to mammals. Moreover this decrease in alkali-lability is correlated with the state of thermal adaptation (antarctic fishes, 53–66%; tropical cichlid fish, 35%). These results provide additional evidence for the notion that the extremely high polarity of brain gangliosides, especially of cold-blooded vertebrates, reflects a very efficient mechanism on the molecular level to keep the neuronal membrane functional under low temperature conditions.     

Possible Involvement of Polysialogangliosides in Nerve Sprouting and Cell Contact Formation: An Ultracytochemical In Vitro Study

In Cichlid fish (Oreochromis mossambicus) primary cell cultures from whole brain and optic tectum, the differentiation-dependent distribution of polysialogangliosides on the outer cell surface has been followed on an ultrastructural level. For this, a two-step labeling technique with the monoclonal mouse antibody Q211, recognizing a polysialoganglioside-associated epitope, followed by a secondary IgM antibody, coupled to colloidal gold sols as an electron-dense marker, has been used. The gold grains are not uniformly distributed over the whole cell surface, but rather are clearly arranged clusters. In cells from freshly hatched larvae, both cell bodies and nerve fibers strongly exhibit the polysialoganglioside epitope on their surface. With progressing development, neuronal cell labeling is more and more restricted to nerve fibers and especially to cellular adhesion zones, including synaptic terminals, thus suggesting a functional involvement of polysialogangliosides in nerve sprouting and initiation of both cell-to-extracellular matrix and cell-to-cell contacts.