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 t he surface of photoreceptor cells and in the interphotoreceptor matrix (IPM). This study was undertaken to facilitate understanding of the m etabolic features of O-linked sialoglycoconjugates in comparison with those of N-linked glycoconjugates in the rat retina. We examined the d evelopmental change in distribution of Gal beta 1,3GalNAc alpha 2,3-si alyltransferase mRNA in rat retinas using in situ hybridization histoc hemistry to detect the synthesis period of O-linked sialoglycans. Posi tive hybridization signal was observed in the ganglion cells throughou t the postnatal days (P) examined, whereas strong signals were detecte d in the photoreceptor inner segments and the inner nuclear layer excl usively at P16 and P18. At P20 and older, only weak or sparse signals were detected in these regions. It is likely that O-linked sialoglycoc onjugates which are detected in the mature IPM, are actively synthesiz ed 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.