Abstract
In a previous study, we reported fast and slow recovery phases of goldfish behavior after optic nerve transection. To understand the molecular mechanism of regrowing optic axons and reforming the retinotectal topography, we identified genes from tectum whose expression is upregulated in the late stage of optic nerve regeneration. A cDNA library constructed from goldfish tectum was screened by differential hybridization with cDNA probes derived from normal or axotomized tecta. One clone was identified as ferritin heavy subunit by high sequence homology. The level of the mRNA in the tectum increased at 30 days and peaked at 60 days after optic nerve transection. The increased expression of the mRNA was detected in the SFGS layer of the tectum by in situ hybridization. On the other hand, Eph/ephrine and neuropirin/semaphorin family are well characterized as an axon guidance molecule for retinotectal topography during development of the visual system. In the present study, therefore the full length of ephrine A2 and semaphorin IIIA cDNAs were cloned from goldfish tectal cDNA library. Their expression pattern and localization in the tectum were determined by in situ hybridization. Our data suggest that ephrine A2 and semaphorin IIIA also work as axon guidance molecules for retinotectal topography after optic nerve lesion, as seen as visual development. [Jpn J Physiol 54 Suppl:S214 (2004)]
