Metabolism of cerebrosides and sulfatides in the nervous system ofXenopus tadpole during metamorphosis
Tóm tắt
Xenopus laevis tadpoles undergoing metamorphosis were used to study the turnover of cerebrosides and sulfatides in the nervous system of the frog. Tadpoles at the beginning of metamorphosis were treated by intraperitoneal injection with [U-14C]glucose and radioactivity incorporated into galactosphingolipids of brain and tail was measured after various times. The specific activity of brain cerebrosides increased rapidly for the first 24 hr after injection, reached a plateau after 48hr, and then declined 40% by 7 days. The specific activity of sulfatides changed somewhat more slowly. Hydroxy fatty acid-containing galactosphingolipids had nearly twice the specific activity compared with their nonhydroxy counterparts in brain. Despite the complete regression of tail nerve cord, metabolism of glycosphingolipids in this tissue also indicated active synthesis as well as degradation during this period. The specific activities of these lipids were similar and all reached a peak 24 hr after injection. Examination of the components of these galactosphingolipids disclosed that only a small fraction (7–25%) of the radioactivity was in the galactose moiety in both brain and tail. The ratios of the radioactivity in fatty acid to that in the sphingoid base were much higher for hydroxycerebroside and hydroxysulfatide than for the nonhydroxy isomers.
Tài liệu tham khảo
Fox, H. 1981. Cytological and morphological changes during amphibian metamorphosis. Pages 327–362,in,L. I. Gilbert andE. Frieden (eds.) Metamorphosis: A Problem in Development Biology, ed. 2, Plenum Press, New York.
Fox, H. 1973. Degeneration of the nerve cord in the tail of Rana temporaria during metamorphic climax: study by electron microscopy, J. Embryol. Exp. Morph. 30:377–396.
Ebbesson, S. O. E. 1976. Morphology of the spinal cord. Pages 679–682,in R. Llinas andW. Precht (eds.), Frog Neurobiology: A Handbook. Springer-Verlag, New York.
Kollros, J. J. 1981. Transitions in the nervous system during amphibian metamorphosis. Pages 445–460,in L. I. Gilbert andE. Frieden (eds.), Metamorphosis: A Problem in Developmental Biology, ed. 2, Plenum Press, New York.
Okamura, N., andKishimoto, Y. 1983. Changes in nervous system glycolipids during metamorphosis ofXenopus laevis. J. Biol. Chem., 258:12243–12246.
Lowry, O. H., Rosebrough, N. J., Farr, L., andRandall, R. J. 1951. Protein measurement with the Folin phenol reagent. J. Biol. Chem. 193:265–275.
Kishimoto, Y.;Radin, N. S. 1965. A reaction tube for Methanolysis; Instability of hydrogen chloride in Methanol, J. Lipid Res., 6:435–436.
Nieuwkoop P. D., andFaber, J. 1967. Normal Table of Xenopus laevis (Daudinin). A Systematical and Chronological Survey of the Development of the Fertilized Egg Till the End of Metamorphosis, Pages 1–260, ed. 2, North-Holland, Amsterdam.
Burton, R. M., Sodd, M. A., andBrady, R. O. 1958. The incorporation of galactose into galactolipids. J. Biol. Chem. 233:1053–1060.
Hauser, G. 1964. Labeling of cerebrosides and sulfatides in rat brain, Biochim. Biophys. Acta 84:212–215.
Radin, N. S., Martin, F. B., andBrown, J. R. 1957. Galactolipid metabolism, J. Biol. Chem. 224:499–507.
Yahara, S., Singh, I., andKishimoto, Y. 1980. Cerebroside and cerebroside III-sulfate in brain cytosol. Evidence for their involvement in myelin assembly. Biochim. Biophys. Acta 619:177–185.