Identifying mRNAs involved potentially in corticopontine projection by modified differential display

The basilar pons plays an important role in the establishment of the corticopontine projection by releasing a diffusible molecule which induces and directs collateral branchings along the corticospinal axon shafts. To reveal the molecule which is involved in the developing process of the corticopontine projection, we attempted to modify the mRNA differential display to search for genes expressed differentially in the basilar pons during the formation of the corticopontine projection by introducing the RGD motif (arginine-glycine-asparate) in the primers of the polymerase chain reaction. With our modification, we were able to identify 99 mRNAs expressed in the basilar pons but not in the cerebral cortex where the apparent pontine-derived activity is not observed. Among these 99 gene fragments, 3 novel fragments could be selected as final candidates of the pontine-derived molecule based on their expression patterns. Modified differential display is thus a promising method for identification of these genes.