Structural characterization of the acidic glycosphingolipids in peripheral nervous system and studies on their biological function.

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We isolated four phosphonoglycosphingolipids, designated FGL-IIa, FGL-IIb, FGL-V and F-21, from the nervous system of A. kurodai by Iatrobeads column chromatography using three solvent systems and elucidated their complete structures, respectively. Pyruvic acid attached as a ketal to O-3 and O-4 of the terminal galactose of the oligosaccharide chain in FGL-IIa, FGL-IIb and FGL-V. F-21 has 3-O-methylgalactose as its non-reducing end sugar and one of its three 2-aminoethylphosphonate molecules is linked to C_6 of N-acetylgalactosamine.We raised a polyclonal antibody against FGL-IIb and examined the antigens that reacted with this anti-FGL-IIb antiserum by TLC-immunostaining. The antiserum reacted with FGL-IIb, FGL-I, FGL-IIa, FGL-V and F-9, which were identified in ganglia and nerve fibers on TLC plates. When cryostat and paraffin sections of the nervous tissue and skin of Aplysia were treated with the antiserum, only nerve bundles were distinctly stained. From histochemical findings in cryostat sections pretreated with chloroform-methanol (2 : 1, v/v) and from results by Western blot analysis of the nervous system, the staining was concluded to be due to glycolipid antigens. In nerve bundles disintegrated with Disperse, periaxonal materials or small periaxonal cells were stained but axons were not stained. This peculiar location of these glycolipids suggests roles of these glycolipids in neurite outgrowth and fasciculation.In primary cultures of Aplysia neurons and in clonal cultures of neuronal cell lines, we have not yet obtained results that indicate whether or not the new glycolipid family has these proposed neurobiological functions.