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 GD_Ia and GT, 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 sixfold of the activity of UDP-N-acetyl-galactosamine: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:lactosylceramide-, CMP-NeuAc:GM_3-, 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.