(
2015-04)
Kingston, Alexandra C. N.; Kuzirian, Alan M.; Hanlon, Roger T.; Cronin, Thomas W.
Cephalopod molluscs are renowned for their colorful and dynamic body patterns, produced by an
assemblage of skin components that interact with light. These may include iridophores,
leucophores, chromatophores, and (in some species) photophores. Here, we present molecular
evidence suggesting that cephalopod chromatophores, small dermal pigmentary organs that
reflect various colors of light, are photosensitive. RT-PCR revealed the presence of transcripts
encoding rhodopsin and retinochrome within the retinas and skin of the squid Doryteuthis
pealeii, and the cuttlefish Sepia officinalis and Sepia latimanus. In D. pealeii, Gqα and squid
TRP channel transcripts were present in the retina and in all dermal samples. Rhodopsin,
retinochrome, and Gqα transcripts were also found in RNA extracts from dissociated
chromatophores isolated from D. pealeii dermal tissues. In D. pealeii, immunohistochemical
staining labeled rhodopsin, retinochrome, and Gqα proteins in several chromatophore
components, including pigment cell membranes, radial muscle fibers, and sheath cells. This is
the first evidence that cephalopod dermal tissues, and specifically chromatophores, may possess
the requisite combination of molecules required to respond to light.