Summary
This study maps the evolutionary history of cryptochrome (Cry) genes across bilaterian species, identifying six major subgroups with evidence of sub- and neofunctionalization events relevant to circadian photoreception. The finding that all cry transcripts show broad, cyclic expression across zebrafish retinal layers supports the hypothesis of autonomous retinal circadian clocks, with implications for understanding how different retinal cell types independently process light-dark information.
Key Findings
- Six major cryptochrome subgroups were identified across bilaterian species through phylogenetic analysis.
- Teleost fish possess up to seven cry genes, crustaceans up to three, and tetrapods up to four, reflecting lineage-specific gene retention and loss.
- Paralogous cry mRNAs showed only partially overlapping expression patterns in larval zebrafish, supporting gene sub- and/or neofunctionalization.
- Daily cry expression in the adult zebrafish retina showed varying oscillation patterns across different retinal cell types, consistent with multiple autonomous circadian clocks within the vertebrate retina.
- Several parasitic or blind species have lost all cry genes, indicating functional dispensability under certain ecological conditions.
Categories
The Science of Light: Examines cryptochrome photoreceptors and their phylogenetic diversity, UV/blue light absorption, and roles in circadian rhythm regulation across species.
Sleep & Circadian Health: Investigates cyclic cry gene expression patterns in zebrafish retinal layers, supporting the existence of multiple autonomous circadian clocks in the vertebrate retina.
Author(s)
M Gesemann, MF Haug, V Lazovic
Publication Year
2012
Related Publications
The Science of Light
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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