Isolation and characterization of multilayered sheath membrane rich in glucocerebroside from shrimp ventral nerve.
A membrane fraction rich in glucocerebroside was isolated from homogenates of ventral nerves of pink shrimp (Penaeus duorarum) by sucrose gradient centrifugation. The membrane fraction was observed at 0.15 M sucrose and was rich in lipids (lipid/protein ratio approximately 15:1). Electron microscopy showed that the fraction was derived from myelin-like multilayered glial membrane ensheathing axons, which has morphological similarities to myelin. Most of the lipids in shrimp nerve, including glucocerebroside, sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, and ethanolamine-plasmalogen, as well as cholesterol, appeared to be concentrated in this fraction. The fatty acids of these phospholipids were exclusively saturated or monounsaturated with C14-C26 chain lengths. The aldehyde moiety of plasmalogens contained only saturated C14-C18 carbon chains. Like glucocerebrosides, the sphingoid base of sphingomyelin consisted mainly of C14-C16 sphingenines and sphinganines, but they also contained significant amounts of C19 and C20 sphinganines. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the proteins in this fraction showed several bands in the 23,000-85,000 Mr range. Radioimmunoassay, however, did not show cross-reactivity with antibodies to myelin basic protein. The functional role of this membrane in relation to mammalian myelin is discussed.
D000818:Animals; D002462:Cell Membrane / Q000032:analysis; D002554:Cerebrosides / Q000032:analysis*; D033364:Decapoda / Q000648:ultrastructure*; D005227:Fatty Acids / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D005963:Glucosylceramides / Q000032:analysis*; D008563:Membrane Lipids / Q000032:analysis; D008565:Membrane Proteins / Q000032:analysis; D008854:Microscopy, Electron; D008970:Molecular Weight; D009186:Myelin Sheath / Q000032:analysis / Q000648:ultrastructure*; D010743:Phospholipids / Q000032:analysis; D013109:Sphingomyelins / Q000032:analysis
D002554:Cerebrosides; D005227:Fatty Acids; D005963:Glucosylceramides; D008563:Membrane Lipids; D008565:Membrane Proteins; D010743:Phospholipids; D013109:Sphingomyelins