Journal of Lipid Research, Vol 33, 1351-1359, Copyright © 1992 by Lipid Research, Inc.
Characteristic distribution of glycolipids in gadoid fish nerve tissues and its bearing on phylogeny
Y Tamai, H Kojima, S Saito, K Takayama-Abe and H Horichi
Department of Biochemistry, Kitasato University School of Medicine, Kanagawa, Japan.
Glycolipids were isolated from nerve tissues of gadoid fishes including
Alaskan pollack and Pacific cod. Their chemical structures were determined
by gas-liquid chromatography and gas chromatography-mass spectrometry, and
their constituents were analyzed in detail and compared with those of
glycolipids from other fish groups. The results revealed that gadoid fish
nerve membranes contain peculiar glycolipid molecular species that are
distinctly different from those in other teleostean fishes and higher
vertebrates. The mole percentage ratio of the four major glycolipids
(cerebroside-sulfatide-galactosylglyceride- sulfogalactosylglyce ride) was
48:12:25:15, indicating profound accumulation of glycoglycerolipids.
Galactosylglyceride and sulfogalactosylglyceride were primarily of the
diacyl type (greater than 90%), the major fatty acids being 16:0 and 18:1.
An abundance of glucocerebroside (25 to 55% of cerebroside) and its fatty
acid ester (37 to 47% of ester cerebroside) was noted. Cerebroside and
sulfatide were characterized by the absence of hydroxy and odd numbered
fatty acids, and 24:1 acid was a predominant component of both
glucocerebroside and galactocerebroside. Subcellular fractionation revealed
that myelin membranes comprised such unusual glycolipid constituents as
those seen in whole nerve tissues. A vertebrate whose nerve membranes
consist of such peculiar glycolipid molecules has not previously been
reported. The characteristics of the glycolipid composition in gadoid
fishes are discussed in relation to myelin functions, physicochemical
properties of nerve membranes, and the phylogenic significance of this fish
group.