Summary
This study profiles transcriptomes of the avian pineal gland and retina to identify candidate clock components, finding circadian regulation of key photopigment genes (melanopsin, cryptochrome 2, peropsin, RGR-opsin) in both tissues. The findings suggest meaningful divergence between diurnal and nocturnal species in photoentrainment mechanisms, which has implications for translating circadian lighting research from rodent models to human (diurnal) applications.
Key Findings
- mRNA for peropsin, RGR-opsin, melanopsin (opn4), and cryptochrome 2 (cry2) was localized to the Inner Nuclear Layer and Retinal Ganglion cell Layers of the chick retina, regions associated with circadian photoreception.
- opn4 and cry2 mRNA were expressed in the photoreceptor layer of the chick retina, where melatonin biosynthesis occurs.
- All four candidate photopigment genes showed circadian-regulated mRNA expression in the pineal gland under both LD and DD conditions.
- Several avian orthologs of mammalian clock genes exhibited oscillating mRNA abundance patterns over a 24-hour period in both daily and free-running conditions.
Categories
The Science of Light: Investigates photoentrainment mechanisms and candidate photopigment genes (melanopsin, cryptochrome, peropsin, RGR-opsin) in avian circadian systems, relevant to understanding divergent photoreception biology across species.
Sleep & Circadian Health: Examines circadian rhythm generation and entrainment in diurnal versus nocturnal species, with implications for understanding light-dark cycle regulation across chronotypes.
Author(s)
C Chaigne, D Sapède, X Cousin, L Sanchou, P Blader
Publication Year
2022
Related Publications
The Science of Light
- Phototransduction by retinal ganglion cells that set the circadian clock
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- The mammalian circadian timing system: organization and coordination of central and peripheral clocks
- Diminished pupillary light reflex at high irradiances in melanopsin-knockout mice
- Melanopsin is required for non-image-forming photic responses in blind mice
Sleep & Circadian Health
- Phototransduction by retinal ganglion cells that set the circadian clock
- The mammalian circadian timing system: organization and coordination of central and peripheral clocks
- The two‐process model of sleep regulation: a reappraisal
- Melanopsin is required for non-image-forming photic responses in blind mice
- Strange vision: ganglion cells as circadian photoreceptors