Expression of C-Jun Following Optic Nerve Injury in Danio Rerio
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Unlike mammals, fish and amphibians exhibit remarkable regenerative properties of the central nervous system. This study focused on the changes in c-jun expression consequent to optic nerve injury in Danio rerio (zebrafish). Known for its function in regulating transcription, c-jun binds with other transcriptional regulators to affect nerve regeneration and cell death in ways that seem paradoxical. I sought to determine if c-jun was differentially expressed in the retina following optic nerve injury as compared to fish which had undergone a similar operation but whose optic nerve had not been injured (sham-operated). Based on previous studies, I hypothesized that expression of c-jun in the retina would significantly increase in fish that suffered injury to the optic nerve compared to those that only underwent collateral tissue damage. Following RNA extraction and cDNA synthesis with reverse transcription polymerase chain reaction (RT-PCR), quantification of c-jun expression was determined by quantitative real time-PCR (qRT-PCR). Expression levels were normalized to expression of a reference gene (ß-actin), yielding relative expression levels. A two way analysis of variance was carried out in order to determine whether there were significant differences in gene expression 3 hours, 24 hours and 168 hours after injury between sham-operated and optic nerve injured fish. Significant differences (p < 0.05) between sham-operated and optic nerve injured retinas were observed at 24 hours and at 168 hours. The significant differences in expression of c-jun corroborated and extended past studies (Veldman et al., 2007, Herdegen et al., 1993). Furthermore, my findings raised the possibility that c-jun expression may be important for optic nerve regeneration. If the ability of fish to regenerate optic nerve has a genetic basis, then one may be able conduct gene therapy treatment in glaucoma patients by identifying the genes that are differentially expressed following optic nerve injury.