DIFFERENTIAL EXPRESSION OF MESSENGER-RNA FOR ALPHA-2,3-SIALYLTRANSFERASE DURING DEVELOPMENT OF RAT RETINA

Glycoconjugates, consisting of O- and N-linked types, are present on the surface of photoreceptor cells and in the interphotoreceptor matrix (IPM). This study was undertaken to facilitate understanding of the metabolic features of O-linked sialoglycoconjugates in comparison with those of N-linked glycoconjugates in the rat retina. We examined the developmental change in distribution of Gal beta 1,3GalNAc alpha 2,3-sialyltransferase mRNA in rat retinas using in situ hybridization histochemistry to detect the synthesis period of O-linked sialoglycans. Positive hybridization signal was observed in the ganglion cells throughout the postnatal days (P) examined, whereas strong signals were detected in the photoreceptor inner segments and the inner nuclear layer exclusively at P16 and P18. At P20 and older, only weak or sparse signals were detected in these regions. It is likely that O-linked sialoglycoconjugates which are detected in the mature IPM, are actively synthesized from P16 to P18 in the rat photoreceptor inner segments, suggesting that the O-linked sialoglycoconjugates in the photoreceptor layer may be stable with little turnover in the mature retina.