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L. Li, P. Li; Circadian and Dopamine Regulation of Red Cone Opsin mRNA Expression in Zebrafish . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3523.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate if the zebrafish circadian visual sensitivity correlates with its opsin gene expression, and to elucidate the mechanisms that underlay opsin mRNA expression. Methods: Total RNA was isolated from adult zebrafish eyes at different times between the day and night while the fish were kept in either a normal light-dark cycle (14:10, LD) or constant (LL) or constant darkness (DD). The expression of long-wavelength cone (LC) opsin mRNA was determined using real-time RT-PCR. Results: Under a normal LD, the expression of LC mRNA is low in the early morning and high in the late afternoon, similar to the fluctuation of behavioral cone sensitivity. This pattern of LC mRNA expression persists in LL and DD for about 24 hours, and then dampens out. Brief light or dark adaptation produces no obvious effects, but exposure to prolonged light or darkness results in the dramatic change of LC mRNA expression. Prolonged light down regulates LC mRNA expression. In contrast, prolonged darkness elevates its expression. Dopamine, a neural modulator in the retina, also plays a role in LC mRNA expression. Exogenous dopamine increases LC mRNA expression by approximately 2-fold. Conclusions: In zebrafish, the circadian rhythm of behavioral visual sensitivity correlates with its circadian-regulated opsin gene expression. The expression of opsin gene is regulated by ambient illumination and dopamine.
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