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A. C. Morris, D. Mari, J. M. Fadool; Sox11b Expression in the Zebrafish Eye Suggests a Role in Retinal Development and Rod Regeneration. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2660. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Unlike mammals, the retinas of teleost fish display remarkable regenerative ability in response to experimental damage or genetic manipulation. We are interested in identifying factors that regulate photoreceptor regeneration in the zebrafish retina. This will increase our understanding not only of the molecular mechanisms of adult retinal regeneration, but may also uncover genes that are important for photoreceptor development during embryogenesis. In a microarray analaysis of retinal RNA purified from wild type zebrafish and from zebrafish that experience rod degeneration, members of the sox family of transcriptional regulators displayed increased expression in response to rod degeneration. Of these, sox11b demonstrated the largest increase over wild-type levels. Therefore, we evaluated the expression pattern of sox11b in adult retinas from wild type, rod-deficient, and cone-deficient zebrafish, as well as during embryonic retinal development.
sox11b expression in the zebrafish retina was examined by RT-PCR and in situ hybridization of embryonic, larval and adult retinal cryosections. Cell proliferation in the retina was visualized by immunodetection of BrdU incorporation. Localization of sox11b expression in different retinal cell types was determined by immunolabeling with antibodies to cell-type specific markers. Expression patterns of sox11b were compared in wild type, transgenic XOPS-mCFP (rod-deficient), and mutant pde6cw59 (cone-deficient) retinas.
In the developing zebrafish eye, sox11b expression was observed throughout the retinal neuroepithelium at 24 hours post fertilization (hpf). Thereafter, sox11b expression became progressively restricted to the persistently neurogenic marginal zone (CMZ), in a pattern very similar to that of the proliferation marker PCNA. At 5 dpf, sox11b expression was observed in the CMZ and in a few cells located in the outer nuclear layer (ONL). In the wild type adult retina, sox11b expression was very low. However, in rod-deficient XOPS-mCFP retinas, sox11b expression was observed in numerous rod precursor cells at the base of the ONL. sox11b expression did not appear to co-localize with BrdU-positive rod progenitor cells.
Our results suggest that sox11b plays a role in both embryonic retinal development and in the generation of rod photoreceptors in adult zebrafish in response to rod degeneration. In the mature retina, sox11b may function after rod progenitor exit from the cell cycle.
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