Synthesis of Retinal Gangliosides During Chick Embryonic Development

Abstract

Embryonic retina cells incorporated radioactivity from D-[6-3H]glucosamine into gangliosides in vitro. The incorporation was higher in retinas from younger embryos. The pattern of labeling of individual gangliosides of the retina changed gradually from a predominant labeling of gangliosides running chromatographically as GD3 (nomenclature of Svennerholm) and GM3 in retinas from 8 day old embryos to a predominant labeling of those running as GD1a and GT1 in retinas from 13-18 day old embryos and newly hatched chicks. The shift in the pattern of labeling correlated with a temporary increase of about 6 times of the activity of UDP-N-acetylgalactosamine:GM3 N-acetylgalactosaminyltransferase occurring between days 8 and 14 of embryonic development and with a regular increase of the activity of the UDP-galactose:GM2 galactosyltransferase occurring from day 8 until hatching. The activities of the CMP-NeuAc [neuraminic acid]:lactosylceramide-, CMP-NeuAc:GM3- and CMP-NeuAc:GM1-sialosyltransferases in the retinas of newly hatched chicks were 40, 20 and 40% in comparison with the corresponding activities determined in retinas of the 8 day old embryo.