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Functional diversification process of opsin genes for teleost visual and pineal photoreceptions
Chihiro Fujiyabu1, Fuki Gyoja2, Keita Sato3
1Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan.
Cellular and Molecular Life Sciences : CMLS
|October 8, 2024
Summary
A unique gene duplication event in fish led to separate genes for vision and pineal light detection. This "domino effect" explains the evolution of distinct visual and pineal opsin genes in teleost fishes.
Area of Science:
- Evolutionary biology
- Genetics
- Molecular biology
Background:
- Most vertebrates possess a five-exon rhodopsin gene for visual photoreception.
- Teleost fishes uniquely have an intron-less rhodopsin gene for vision and an intron-containing rhodopsin (exo-rhodopsin) gene for pineal photoreception.
Purpose of the Study:
- To investigate the evolutionary origin of intron-less visual rhodopsin and intron-containing pineal opsin genes in Actinopterygii fishes.
- To elucidate the functional diversification of opsin genes in teleost visual and pineal photoreception.
Main Methods:
- Comparative genomic analysis of rhodopsin and pinopsin genes across various Actinopterygii lineages.
- Phylogenetic analysis to trace gene duplication and functional evolution events.
Main Results:
- Retroduplication after Polypteriformes branching generated the intron-less rhodopsin gene for vision.
- The parental intron-containing rhodopsin gene was repurposed for pineal photoreception in the Teleostei ancestor.
- Pinopsin functions as a green-sensitive opsin in tarpon but is lost in other teleosts due to redundancy.
Conclusions:
- A single retroduplication event triggered a cascade of changes, leading to the diversification of teleost visual and pineal opsin genes.
- This evolutionary scenario highlights how gene duplication and functional repurposing shape sensory systems.
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