engleski

Complex gangliosides in fish brain

Glycolipids are dominant glycans in vertebrate brains. Complex gangliosides GD1a, GD1b and GT1b are ubiquitously expressed on neurons while GM1 is marker of fibers in all reptilian, bird and mammalian brains. Complete lack of complex gangliosides does not interrupt brain morphogenesis but does affect long term myelin and axon maintenance due to interaction of GD1a and GT1b with oligodendrocyte ligand MAG. The same axon/myelin preserving interaction turns into regeneration obstructing in the case of injury in adult brain. In contrast to higher vertebrates, fish and amphibian brains are deficient in complex gangliosides but well known as regeneration-competent. Using antibodies for GM1, GD1a, GD1b and GT1b we investigated difference in distribution of gangliosides in brains of sturgeon (Fig. 1), catfish (Fig. 2), carp (Fig. 3), trout (Fig. 4), pike (Fig. 5) and perch (Fig. 6). Contrary to other vertebrates that have uniform pattern of ganglioside expression, investigated species of Actinopterygii varied in ganglioside expression. All but one species (sturgeon) expressed GM1 as neuronal marker, not being present on fibers like in mammalian brain. Catfish, carp and trout express GM1 and GT1b on individual neurons in telencephalon, hypothalamic nucleai, granular neurons in cerebellum and stratum periventriculare in optic tectum. GD1a is almost undetectable in trout, GD1b in catfish and carp while GT1b in perch brain. Brain of sturgeon has expression of complex gangliosides resembling one observed in higher vertebrates and its regeneration-competence could be farther investigated.

gangliosides; fish brain; regeneration

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