RESUMEN
The developmental pattern of expression of the UDP-GalNAc:GM3 N-acetylgalactosaminyltransferase (GalNAc-T) gene was examined in the rat brain and retina. A GalNAc-T cDNA cloned from a rat olfactory bulb cDNA library was used as a probe for Northern blot and in situ hybridization experiments and a rabbit polyclonal antibody to rat GalNAc-T peptide was used for Western blot analysis. In Northern blot experiments, a single approximately 3 kb transcript was detected both in brain and retina. In brain, the abundance of this transcript increased from E15 to PN1-5 and then declined while, in retina, it increased steadily from PN1 to PN13-24. The developmental trends of GalNAc-T mRNA expression, GalNAc-T immunoreactive protein and GalNAc-T activity were comparable in brain. In retina, however, GalNAc-T activity and GalNAc-T peptide immunoreactivity followed developmental patterns that were similar between them and different from that of the specific mRNA. Results suggest that post-transcriptional controls of the GalNAc-T gene expression operate in the rat CNS, which are particularly evident in retina. The expression of the GalNAc-T gene in glial and neuronal cells was examined in rat retina cell cultures by in situ hybridization. The GalNAc-T mRNA was abundant in GM1+/GD3+ neurons and almost absent in the flat, GM1-/GD3+ Müller glia-derived cells.