The expression of transferrin binding protein in the turtle nervous system

Transferrin binding protein (TfBP) is a cytoplasmic glycoprotein that was originally isolated from the chick oviduct. As we previously demonstrated the constitutive expression of TfBP in the avian nervous system, in this study we examined whether TfBP is expressed in the reptilian nervous system. In accordance with previous findings in the chicken, oligodendrocytes were most prominently labeled by antiserum to TfBP. Great variability was observed between different regions of the central nervous system (CNS) in terms of TfBP-labeled oligodendrocyte numbers. In the retina, TfBP was localized specifically in the cells that are morphologically oligodendrocytes and present in the optic nerve and the ganglion cell layer. TfBP staining was also seen in the Schwann cells of peripheral nerves. Furthermore, choroid plexus cells and capillary endothelial cells similarly exhibited strong reactions. These results may reflect the fact that the homology of nervous system genes is conserved between close phylogenetic lines, and proove the potential of TfBP as a marker for oligodendrocytes in avian as well as reptile.