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N. Martinez-Ruiz, Sr., M. Blazquez, F. Piferrer, J. De Juan; The Outer Segments of the Teleost Photoreceptors Have Aromatase (cyp19a2) Whose Amount Is Greatest in Dark-Adapted Retinas Than in Light-Adapted Ones. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3057.
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Aromatase catalyzes the conversion of androgens into estrogens.It has been implicated in the regulatory effect of estrogens on neural differentiation and neural plasticity, and it is widely expressed in several locations of the central nervous system, including the retina. Recently, we found the aromatase promoter sequence, in retina of a teleost (sea bass), and verify that it has binding sites to transcription factors related to cone and rod photoreceptors (Crx-cone-rod homeobox). The aim of this work is show the presence of aromatase in photoreceptors and quantify the possible differences between light- and dark-adapted retinas.
The study was performed insea bass (Dicentrarchus labrax). Before to sacrifice, fishes were long time light- and dark- adapted (>2h), and their retinas processed for semiquantitative PCR which was used to measure the neural isoform of aromatase (Cyp19A2) gene expression in sea bass retinas. Final values were normalized with those of 18S rRNA in the same samples. An Immunocytochemical study was performed in sections from LR-white embedded retinas, using a polyclonal antibody against a consensus sequence of fish aromatases.
In dark- adapted retinas, the mean of Cyp19A2 gene expression was near twofold the expression of the light- adapted ones. In immunocytochemical studies, the outer segments of cone and rod photoreceptors are clearly reactive to anti-aromatase in both lightness conditions, being more intense in dark- adapted retinas.
As we known that the trancription factor Crx regulates the transcription of rodopsin, the differences in expression of aromatase in light- and- dark adaptation, suggest that this enzyme should have and important role in circadian rhyme and probably in sexual dimorphism of Dicentrarchus labrax retina.
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