Circadian rhythm and light regulate opsin mRNA in rod photoreceptors
Abstract
Disk membranes in the outer segment of rod photoreceptors are continuously renewed, being assembled at the outer segment base, displaced outward by new disks and eventually shed at the tip1. In lower vertebrates, disk assembly occurs with a diurnal rhythm with 2-4% of the outer segment length produced daily2,3. We have discovered that in toad and fish retinas the level of mRNA for opsin, the most abundant protein in rod disks4, fluctuates with a daily rhythm and is regulated both by light and by a circadian oscillator5. The mRNA level rises before light onset, remains high during the light phase of a diurnal cycle and decreases four to tenfold during the dark phase. In constant darkness, mRNA eleva-tion occurs during subjective daytime. At night, rod opsin mRNA can be elevated by exposure to light.
- Publication:
-
Nature
- Pub Date:
- February 1989
- DOI:
- 10.1038/337454a0
- Bibcode:
- 1989Natur.337..454K