ABSTRACT
Migratory species experience morphological and physiological changes during transitions between different life stages. In particular, modification of sensory systems is critical for animals to adapt to new environments. For example, to prepare for entry into seawater, salmonids undergo smoltification with dramatic changes in ultraviolet photoreceptors and polarized vision, which are important for orientation and foraging behaviours. Extraretinal organs are also involved in photoreception; however, the ontogenetic development of extraretinal photoreceptors is not well known, especially in migratory species. Here, we investigated whether rainbow trout dermal photoreceptors, melanophores, undergo change in spectral sensitivity during smoltification and which candidate molecules may account for this ontogenetic alteration. Our results showed that, contrary to parr melanophores which are insensitive to light, smolt melanophores displayed chromatic photoresponses with the emergence of cryptochrome and melanopsin expression. We suggest that these modifications may benefit the active foraging behaviour of smolts and enable adaptation to variable environments.
Footnotes
Author Contributions Conceived and designed the experiments: SCC and CWH. Performed the experiments: SCC. Analyzed the data: SCC. Contributed reagents/materials/analysis tools: CWH. Wrote the paper: SCC. Critically read the manuscript: RMR and CWH.
Competing interests The authors have no competing interests to declare.
- Received August 26, 2014.
- Accepted September 21, 2014.
- © 2014. Published by The Company of Biologists Ltd
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