Murine BC1 RNA in dendritic fields of the retinal inner plexiform layer

Rodent BC1 RNA is a non-messenger RNA polymerase III transcript that is almost exclusively expressed in nerve cells. BC1 RNA has been localised in somatic and dendritic domains of neurons, and its location has been interpreted to indicate a functional role in extrasomatic postsynaptic protein synthesis. In previous in situ hybridisation experiments, it has been demonstrated that in the retina most of the BC1 labelling signal was confined to the ganglion cell layer and the inner plexiform layer. Dendritic processes of several types of neurons form the neuritic plexus of the inner plexiform layer, and in order to determine the contribution of ganglion cells to the BC1 labelling signal, we eliminated this cell type by transecting the optic nerve unilaterally in newborn mice. Deletion of the ganglion cells resulted in a significant reduction although not a complete elimination of the BC1 signal in the inner plexiform layer. These data indicate that dendritic processes of both ganglion cells and amacrine cells contain BC1 RNA.