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Ontogeny of melanophore photosensitivity in rainbow trout (Oncorhynchus mykiss).

Chen SC, Robertson RM, Hawryshyn CW - Biol Open (2014)

Bottom Line: Extraretinal organs are also involved in photoreception; however, the ontogenetic development of extraretinal photoreceptors is not well known, especially in migratory species.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Queen's University, Kingston, ON K7L 3N6, Canada shyhchi.chen@mail.huji.ac.il.

No MeSH data available.


Related in: MedlinePlus

Pigmentation and melanophore counts of rainbow trout parr and smolt caudal fins.Pigmentation of (A) parr and (B) smolt. In close-ups of the caudal fins on the right of the images, note that in smolts the number of melanophores increased and more melanophores were present in the area between fin rays. (C) The number of melanophores in the area between fin rays increased in smolt (n = 11 for each group; also see supplementary material Table S1). Scale bars: 2 cm.
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f01: Pigmentation and melanophore counts of rainbow trout parr and smolt caudal fins.Pigmentation of (A) parr and (B) smolt. In close-ups of the caudal fins on the right of the images, note that in smolts the number of melanophores increased and more melanophores were present in the area between fin rays. (C) The number of melanophores in the area between fin rays increased in smolt (n = 11 for each group; also see supplementary material Table S1). Scale bars: 2 cm.

Mentions: Many salmonids undergo morphological and physiological changes during ontogeny. In particular, smoltification accomplishes the transformation from the parr that is essential for an anadromous species prior to its seaward migration. Modulation of sensory systems is critical for adaptation to distinct habitats at different life stages. Chromatophores are the primary agents contributing to body coloration and mediating body coloration changes in response to light. Therefore, any morphological or physiological change of chromatophores, such as cell numbers or the ability to translocate pigment granules, will lead to the modifications of body patterns and pigmentations. In the present study, we aimed at understanding how the dermal photosensory system of migratory species develops at different life stages. First, we investigated ontogenetic changes of melanophore distributions in parrs and smolts of rainbow trout (Oncorhynchus mykiss). We found that the patterns of melanophore distribution in caudal fin tissues of parrs and smolts were different. In parrs, most melanophores were restricted to the regions near fin rays (Fig. 1A). During smoltification, melanophores increased in number and extended their distribution to the region between fin rays. Thus, smolts had darker caudal fins with more melanophores, notably in the area between fin rays (Fig. 1B,C). Eventually, the development of melanophores leads to morphological color change of O. mykiss.


Ontogeny of melanophore photosensitivity in rainbow trout (Oncorhynchus mykiss).

Chen SC, Robertson RM, Hawryshyn CW - Biol Open (2014)

Pigmentation and melanophore counts of rainbow trout parr and smolt caudal fins.Pigmentation of (A) parr and (B) smolt. In close-ups of the caudal fins on the right of the images, note that in smolts the number of melanophores increased and more melanophores were present in the area between fin rays. (C) The number of melanophores in the area between fin rays increased in smolt (n = 11 for each group; also see supplementary material Table S1). Scale bars: 2 cm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232760&req=5

f01: Pigmentation and melanophore counts of rainbow trout parr and smolt caudal fins.Pigmentation of (A) parr and (B) smolt. In close-ups of the caudal fins on the right of the images, note that in smolts the number of melanophores increased and more melanophores were present in the area between fin rays. (C) The number of melanophores in the area between fin rays increased in smolt (n = 11 for each group; also see supplementary material Table S1). Scale bars: 2 cm.
Mentions: Many salmonids undergo morphological and physiological changes during ontogeny. In particular, smoltification accomplishes the transformation from the parr that is essential for an anadromous species prior to its seaward migration. Modulation of sensory systems is critical for adaptation to distinct habitats at different life stages. Chromatophores are the primary agents contributing to body coloration and mediating body coloration changes in response to light. Therefore, any morphological or physiological change of chromatophores, such as cell numbers or the ability to translocate pigment granules, will lead to the modifications of body patterns and pigmentations. In the present study, we aimed at understanding how the dermal photosensory system of migratory species develops at different life stages. First, we investigated ontogenetic changes of melanophore distributions in parrs and smolts of rainbow trout (Oncorhynchus mykiss). We found that the patterns of melanophore distribution in caudal fin tissues of parrs and smolts were different. In parrs, most melanophores were restricted to the regions near fin rays (Fig. 1A). During smoltification, melanophores increased in number and extended their distribution to the region between fin rays. Thus, smolts had darker caudal fins with more melanophores, notably in the area between fin rays (Fig. 1B,C). Eventually, the development of melanophores leads to morphological color change of O. mykiss.

Bottom Line: Extraretinal organs are also involved in photoreception; however, the ontogenetic development of extraretinal photoreceptors is not well known, especially in migratory species.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.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Queen's University, Kingston, ON K7L 3N6, Canada shyhchi.chen@mail.huji.ac.il.

No MeSH data available.


Related in: MedlinePlus