Expression of distribution of alpha 2,3-sialyltransferase mRNA in rat cornea.

The glycocalyx, present on the surface of the corneal epithelium, contains sialoglycoconjugates. The developmental change in the sialylated residues may be evaluated by examining the expression of the sialyltransferase mRNA. We examined the distribution of Gal beta 1,3GalNAc alpha 2,3-sialyltransferase mRNA in rat corneas during development using in situ hybridization histochemistry to detect the starting point of the synthesis of O-linked sialoglycoconjugates. Eyelid opening occurred between postnatal days 14 (P14) and 16 (P16). In the corneal epithelium, little hybridization signal was observed until P12, whereas distinct hybridization signals were identified at P14 and thereafter. The expression of alpha 2,3-sialyltransferase mRNA is developmentally regulated, based on the programmed time-course of the gene expression, and the corneal epithelium may start to synthesize O-linked sialoglycoconjugates prior to the critical eyelid opening stage.