Glycosphingolipid biosynthesis in early chick embryos

Authors


Correspondence to H. Wiegandt, Physiologisch-Chemisches Institut, Philipps-Universität, Lahnberge, Karl-von-Frisch-Straβe, D-3550 Marburg/Lahn, Federal Republic of Germany.

Abstract

Early chick embryos at the age of 22 h (neurula stage) and 48 h (20–25 somite stage) were explanted from eggs and cultured in vitro in the presence of radioactive sugar precursors. Metabolically labelled glycosphingolipids were isolated. Amongst these, neutral and acidic components, the latter including sulfatide and gangliosides, were identified. Cleavage by exoglycosidases, as well as immunostaining with antibodies on thin-layer plates, showed that at both embryonic stages glycosphingolipids were synthesized that belong to the globo series (globoside, Forssman glycolipid), the lacto series (lactoneotetraosylceramide, nLc4Cer, and two nLc4Cer-based gangliosides, a monosialo and a disialo species), and the ganglio series (ganglioside Gtet1a and higher sialylated derivatives).

Abbreviations
CMH

ceramide monohexoside

CDH

ceramide dihexoside

CTH

ceramide trihexoside

CtetH

ceramide tetrahexoside

CpentH

ceramide pentahexoside. Gangliosides are designated according to their constituents by using short-hand notations as detailed earlier [24] [see also Eur. J. Biochem. 79, 11–21 (1979)]: Ggal1

 

NeuAc-GalCer

Glac1

II3NeuAc-LacCer

Glac2

II3(NeuAc)2-LacCer

Gtri1

II3NeuAc-Gg3Cer

Gtet1a

II3NeuAcGg4Cer

Gtet2a

IV3NeuAc-,II3NeuAc-Gg3Cer

Gtet2b

II3(NeuAc)2-Gg4Cer

Gtet3b

IV3NeuAc-,II3(NeuAc)2-Gg4Cer

HPTLC

highperformance thin-layer chromatography

PBS

phosphate-buffered saline

 

TLC

 

thin-layer chromatography

Enzymes
 

α-Galactosidase (EC 3.2.1.22)

 

β-galactosidase (EC 3.2.1.23)

 

α-N-acetylgalactosaminidase (EC 3.2.1.49)

 

β-N-acetylhexosaminidase (EC 3.2.1.30)

 

neuraminate glycohydrolase or sialidase (EC 3.2.1.18)

Ancillary