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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.


Spectral sensitivity of smolt melanophores and candidate photopigments involved in melanophore photosensitive processes.(A,B) Incident light triggered a smolt melanophore to aggregate or disperse inner pigment granules (melanosomes): (A) aggregation at 380 nm; (B) dispersion at 480 nm. (C) Melanophores responded to light in a wavelength-dependent manner. Aggregations occurred with UV and short wavelength illumination and dispersions with middle and long wavelength illumination. (D) Western blot analysis of photopigment proteins of the integumentary tissues of parrs and smolts. Proteins extracted from caudal fins of parrs and smolts were subjected to western blot analysis. Blots were probed with antibodies against UVS, Cry, OPN4, and actin which served as a loading standard. After incubation with NBT/BCIP, UVS, Cry, and OPN4, and actin were detected at their expected sizes (in kDa): UVS = ∼40; Cry = ∼66; OPN4 = ∼63; actin = ∼42. Scale bars: 50 µm.
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f02: Spectral sensitivity of smolt melanophores and candidate photopigments involved in melanophore photosensitive processes.(A,B) Incident light triggered a smolt melanophore to aggregate or disperse inner pigment granules (melanosomes): (A) aggregation at 380 nm; (B) dispersion at 480 nm. (C) Melanophores responded to light in a wavelength-dependent manner. Aggregations occurred with UV and short wavelength illumination and dispersions with middle and long wavelength illumination. (D) Western blot analysis of photopigment proteins of the integumentary tissues of parrs and smolts. Proteins extracted from caudal fins of parrs and smolts were subjected to western blot analysis. Blots were probed with antibodies against UVS, Cry, OPN4, and actin which served as a loading standard. After incubation with NBT/BCIP, UVS, Cry, and OPN4, and actin were detected at their expected sizes (in kDa): UVS = ∼40; Cry = ∼66; OPN4 = ∼63; actin = ∼42. Scale bars: 50 µm.

Mentions: Subsequently, we examined if melanophore photoresponses undergo ontogenetic change during smoltification. Under illumination, parr melanophores did not show obvious photoresponse regardless of wavelengths (n = 16; supplementary material Fig. S1); Conversely, light triggered smolt melanophores to aggregate or disperse their pigment granules, melanosomes (Fig. 2A,B). Smolt melanophores showed photoresponses in a wavelength-dependent manner. Aggregations occurred in the UV (380–400 nm) region and dispersions at 420–600 nm (n = 8; Fig. 2C). Furthermore, the spectral sensitivity curve showed two response peaks at 380 and 480 nm (Fig. 2C), suggesting that two light-sensitive molecules could be involved in the photoresponses: one photopigment being responsible for aggregation in the UV and short wavelengths and the other for dispersion in the middle and long wavelengths. This biphasic photosensitivity of rainbow trout melanophores is similar to the spectral characteristics of many extraretinal photoreceptors showing sensitivity to short- and middle-wavelength regions (Shand and Foster, 1999).


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

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

Spectral sensitivity of smolt melanophores and candidate photopigments involved in melanophore photosensitive processes.(A,B) Incident light triggered a smolt melanophore to aggregate or disperse inner pigment granules (melanosomes): (A) aggregation at 380 nm; (B) dispersion at 480 nm. (C) Melanophores responded to light in a wavelength-dependent manner. Aggregations occurred with UV and short wavelength illumination and dispersions with middle and long wavelength illumination. (D) Western blot analysis of photopigment proteins of the integumentary tissues of parrs and smolts. Proteins extracted from caudal fins of parrs and smolts were subjected to western blot analysis. Blots were probed with antibodies against UVS, Cry, OPN4, and actin which served as a loading standard. After incubation with NBT/BCIP, UVS, Cry, and OPN4, and actin were detected at their expected sizes (in kDa): UVS = ∼40; Cry = ∼66; OPN4 = ∼63; actin = ∼42. Scale bars: 50 µm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4232760&req=5

f02: Spectral sensitivity of smolt melanophores and candidate photopigments involved in melanophore photosensitive processes.(A,B) Incident light triggered a smolt melanophore to aggregate or disperse inner pigment granules (melanosomes): (A) aggregation at 380 nm; (B) dispersion at 480 nm. (C) Melanophores responded to light in a wavelength-dependent manner. Aggregations occurred with UV and short wavelength illumination and dispersions with middle and long wavelength illumination. (D) Western blot analysis of photopigment proteins of the integumentary tissues of parrs and smolts. Proteins extracted from caudal fins of parrs and smolts were subjected to western blot analysis. Blots were probed with antibodies against UVS, Cry, OPN4, and actin which served as a loading standard. After incubation with NBT/BCIP, UVS, Cry, and OPN4, and actin were detected at their expected sizes (in kDa): UVS = ∼40; Cry = ∼66; OPN4 = ∼63; actin = ∼42. Scale bars: 50 µm.
Mentions: Subsequently, we examined if melanophore photoresponses undergo ontogenetic change during smoltification. Under illumination, parr melanophores did not show obvious photoresponse regardless of wavelengths (n = 16; supplementary material Fig. S1); Conversely, light triggered smolt melanophores to aggregate or disperse their pigment granules, melanosomes (Fig. 2A,B). Smolt melanophores showed photoresponses in a wavelength-dependent manner. Aggregations occurred in the UV (380–400 nm) region and dispersions at 420–600 nm (n = 8; Fig. 2C). Furthermore, the spectral sensitivity curve showed two response peaks at 380 and 480 nm (Fig. 2C), suggesting that two light-sensitive molecules could be involved in the photoresponses: one photopigment being responsible for aggregation in the UV and short wavelengths and the other for dispersion in the middle and long wavelengths. This biphasic photosensitivity of rainbow trout melanophores is similar to the spectral characteristics of many extraretinal photoreceptors showing sensitivity to short- and middle-wavelength regions (Shand and Foster, 1999).

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.