Prolonged exposure to constant, high intensity light leads to apoptosis of the photoreceptors in the outer nuclear layer of the zebrafish retina. The retina has the ability to regenerate these lost photoreceptors through a response in which inner nuclear layer cells proliferate, migrate to the outer nuclear layer, and differentiate into rod and cone photoreceptors. Recent studies indicate that the Müller glia, the only non-neuronal cell type found in the retina, may be the inner nuclear layer source of the regenerated photoreceptors. I am using transgenic and molecular techniques to further investigate the roles of the Müller glia in the retinal regeneration response. We propose that these roles include providing a migrational scaffold for proliferating neuronal precursor cells, intercellular signaling, and neuronal cell production.
Figure 1. Müller glial proliferation in response to constant light. After 36 hours of constant light treatment of albino tg(GFAP:EGFP)nt zebrafish, a large proliferative response is observed (through PCNA co-labeling) in EGFP-expressing Müller glia (arrows).
1. Kassen, S.C., Ramanan, V., Montgomery, J.E., Burket, C.T., Liu, C.G., Vihtelic, T.S., and Hyde, D.R. Time course analysis of gene expression during light-induced photoreceptor cell death and regeneration in albino zebrafish. J. Neurobiol. in press.
