J. Biol. Chem., Vol. 258, Issue 20, 12243-12246, 10, 1983
Changes in nervous system glycolipids during metamorphosis of Xenopus laevis
N Okamura and Y Kishimoto
Qualitative and quantitative changes occurring in the myelin marker
glycolipids, cerebrosides, sulfatides, and monogalactosyl diglyceride, in
the nervous system (brain, spinal cord, and tail) of Xenopus laevis during
its metamorphic stages were analyzed by normal and reverse-phase high
performance liquid chromatography. The concentration of these glycolipids
increased rapidly in brain until the tadpole reached the middle of
metamorphosis, fluctuated slightly, decreased until metamorphosis was
completed, and increased once more as the frog matured. Similar changes
were observed in the spinal cord, but the decrease of glycolipids occurred
at a later stage of metamorphosis. The glycolipid level in tail nerve
reached a peak at the beginning of metamorphosis and then rapidly
decreased. The ratios of hydroxycerebroside and hydroxysulfatide to
respective nonhydroxylipids in brain, spinal cord, and tail remained
constant throughout the metamorphic change but differed in each tissue. The
tail contained the highest ratio. The glycolipids in sciatic nerve
generated during the metamorphosis had an even higher hydroxyl
lipid/nonhydroxy lipid ratio. The cerebrosides contained extremely high
concentrations of monounsaturated fatty acids with very long carbon chains
(C22-C25) and this homolog composition remained almost unchanged throughout
metamorphosis. These results indicate that active degradation of these
glycolipids, and probably of myelin, occurs but the glycolipid composition
of myelin appears to remain the same throughout the metamorphic process.
The significance of these findings is discussed from a morphological
standpoint.
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