Behavior of sugar derivatives in procedures for ganglioside isolation

Gangliosides in axolemmal and synaptic membrane fractions from developing rats: effects of maternal ethanol consumption on offspring

Previous work from this laboratory has shown that in utero exposure to ethanol significantly alters the synthesis of glycoproteins in synaptic, axolemmal, and myelin membranes from developing rats. In an attempt to determine whether in utero exposure to ethanol similarly alters the synthesis of other glycoconjugates involved with cell-cell interactions, the present study examined the influence of chronic maternal ethanol consumption prior to parturition on the content and synthesis of gangliosides in axolemmal and synaptic plasma membranes from developing rats. The results demonstrate that, in contrast to central nervous system glycoproteins, synaptic and axolemmal glycolipids are minimally affected by in utero exposure to ethanol. At all ages examined (17 to 34 days of age), the offspring of control and ethanol-treated rats had a comparable distribution of radiolabel among synaptic and axolemmal gangliosides, a normal concentration of ganglioside sialic acid in synaptic plasma membranes, and a near-normal distribution of sialic acid among synaptic gangliosides. The present study provides evidence which indicates that the radiolabeling patterns of axolemmal and synaptic membrane gangliosides are similar. Specifically, the most heavily labeled synaptic and axolemmal gangliosides were GT1b (20-37% of the total radioactivity) and GD1a (20-32%). A smaller proportion of radioactivity was associated with GD1b (approximately 11-16%), GM1 (5-10%), and GQ1b (4-11%), as well as with GD3 and the other monosialogangliosides (less than 5%). During the age period examined the proportion of radioactive GT1b increased in both membrane fractions.

Procedure for isolation of gangliosides in high yield and purity: simultaneous isolation of neutral glycosphingolipids

While several methods for ganglioside extraction and isolation have been described, relatively little attention has been given to the effectiveness of separation from peptides, phospholipids, and various low-molecular-weight contaminants. A procedure is described for isolation of gangliosides in high purity and good yield from 1- to 400-mg samples (wet wt). A key step was mild acidification following homogenization, designed to dissociate gangliosides from lipophilic peptides which coextracted into organic solvents. This has proved particularly helpful for myelin and myelin-containing tissues (e.g., white matter, nerve) whose proteins have presented special problems in ganglioside isolation. In this study isolation was effected by consecutive chromatographies on Sephadex LH-20, DEAE-Sephadex, and silica gel following the initial acidification. The method applied to bovine white matter gave tissue concentrations (calculated from yields and radiolabeled tracer recoveries) that were similar to those obtained with three previously described procedures; however, peptide contaminants were an order of magnitude lower. Removal of low-molecular-weight contaminants, including nucleotide sugars, was virtually complete. In addition to ganglioside isolation the method can be used to obtain neutral glycosphingolipids as well. It is believed to have broad applicability to a diversity of tissues.