Abstract
Purpose: :
Many mutations which cause inherited retinal diseases such as retinitis pigmentosa (RP) have been identified. However, the precise mechanism of photoreceptor cell death in such diseases remains unknown. The purpose of our study was to produce transgenic zebrafish with one of the rhodopsin mutations at position 344 (Q344X), which is associated with autosomal dominant retinitis pigmentosa (ADRP) in human, and to investigate the phenotype in such transgenic zebrafish.
Methods: :
We used the tol2 transposon system to produce transgenic zebrafish with the rhodopsin Q344X mutation associated with ADRP in human for analysis. This Q344X transgenic fish was then crossed with a fish line whose photoreceptors can be visualized in the zebrafish rhodopsin promoter-driven green fluorescent protein (GFP). The number of surviving photoreceptors on the cryosections was counted by means of fluorescent microscopy for both wild type and Q344X transgenic fish, within 2, 3, 4, 5 and 7 days after fertilization. In addition, we compared the number of surviving photoreceptor cells of the continuous 800lux light exposure group to that of the control group (normal cycle: 200lux for 14 hours, 10 hours of blackout) in the Q344X transgenic fish within 5 days after fertilization.
Results: :
The number of surviving photoreceptor cells was not significantly different in wild type and Q344X transgenic fish within 2, 3 and 4 days after fertilization. On the other hand, the number of surviving photoreceptor cells in the Q344X retina was significantly reduced compared with that in wild type within 5 and 7 days after fertilization (p<0.05). The number of photoreceptor cells showed no significant difference between the continuous light exposure and control groups of Q344X transgenic fish within 5 days after fertilization.
Conclusions: :
The number of surviving photoreceptor cells started to decrease from 5 days after fertilization in Q344X transgenic compared with wild type zebrafish. The photoreceptor cell death in Q344X transgenic zebrafish was not markedly accelerated by light exposure.
Keywords: retinal degenerations: cell biology • transgenics/knock-outs • photoreceptors