"The cDNA sequence of the rhodopsin gene of the cuttlefish Sepia officinalis (L.) (Sub-class Coleoidea, Order Sepiida) is presented, together with an analysis of the structure of the gene."

"A proline-rich C terminus is present; this structure is characteristic of cephalopod rhodopsins."

"An intron is present that splits codon 107, in contrast to the intronless rhodopsin gene in two species of myopsid squid."

"A spectral tuning model involving substitutions at only three amino acid sites is proposed for the spectral shifts between the rhodopsins of Sepia officinalis, three species of squid and Paroctopus defleini."

"In common with all invertebrate opsins studied so far, the equivalent site to the counterion in vertebrate opsins is occupied by an aromatic amino acid."

"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, Gqalpha and squid TRP channel transcripts were present in the retina and in all dermal samples."

"Rhodopsin, retinochrome and Gqalpha transcripts were also found in RNA extracts from dissociated chromatophores isolated from D. pealeii dermal tissues."

"Immunohistochemical staining labeled rhodopsin, retinochrome and Gqalpha 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."

"We found that light causes chromatophores to expand in excised pieces of Octopus bimaculoides skin. We call this behavior light-activated chromatophore expansion (or LACE)."

"We used antibodies against r-opsin phototransduction proteins to identify sensory neurons that express r-opsin in the skin."

"of LACE to be 480 nm. Consistent with our hypothesis, the maximum sensitivity of the light sensors underlying LACE closely matches the known spectral sensitivity of opsin from octopus eyes."

"LACE in isolated preparations suggests that octopus skin is intrinsically light sensitive and that this dispersed light sense might contribute to their unique and novel patterning abilities."

"Our data suggest that a common molecular mechanism for light detection in eyes may have been co-opted for light sensing in octopus skin and then used for LACE."

"By creating an action spectrum for the latency to LACE, we found that LACE occurred most quickly in response to blue light."

"The RNA expression of Ov-Rhodopsin, Ov-retinochrome, and Ov-GRK1 was found and quantified in the skin and also localized in different sucker types and the optic lobes."

"Each of the approximately 1000 suckers contributes to the distributed light perception system, collectively acquiring environmental information that could support eye vision."

"The optic lobes, which are part of the central nervous system, could be directly involved in light detection, in addition to their role in the integration of sensory information."

"We found that fin central muscles, hair cells (epithelial primary sensory neurons), arm axial ganglia, and sucker peduncle nerves all express rhodopsin and retinochrome proteins."

"Our findings indicate that these animals possess an unexpected diversity of extraocular photoreceptors and suggest that extraocular photoreception using visual opsins and visual phototransduction machinery is far more widespread throughout cephalopod tissues than previously recognized."

"We show, for the first time, that the O. vulgaris GRK1 gene is expressed in the sucker rim epithelium, in addition to its expression in the retina and skin."

"By quantifying the relative mRNA in different sucker types at several arm levels, we show that expression is not uniform throughout the octopus arm."

"Our data suggest a light-sensing ability to octopus suckers, adding to their known functions in touch/chemo sensation."

"The results showed that the axial nerve cord is strongly responsive to light stimulation of the arm and that the response travels along the length of the axial nerve cord."

"Blue light generated the strongest neural activity while red and green light also induced responses."

"Light-induced neural activity was mediated through the aboral arm skin and by the oral-side skin and suckers."

"In response to illumination, the arm tip reacts in a reflex-like manner, folding in and moving away from the light beam."

"In contrast to the local activation and control of LACE, the phototactic response is mediated by the brain, although it is expressed in a reflex-like pattern."

"Observations of the octopuses revealed that their arm tips are folded in during the daytime, whereas at night they are extended."

"The mRNA coding for opsin from various body regions was amplified and sequenced, and gene expression was detected in fin and ventral skin samples."

"the opsin in the fin is identical to that of the retina (λmax=492 nm), and the ventral transcripts are also unlikely to be spectrally different"

"Cuttlefish, along with a number of other cephalopod species, have been shown to be colour-blind."

"these findings suggest a possible additional mechanism of light sensing and subsequent skin patterning."

"This 'distributed sensing' could supplement the otherwise visually driven dynamic camouflage system by assisting with colour or brightness matching to adjacent substrates."

"the amino acid sequence of the opsin polypeptide that these transcripts would produce was identical in retina and fin tissue samples, but the ventral skin opsin transcripts differed by a single amino acid."

"We identified 6 opsins, 2 cryptochromes and 1 visual arrestin in Sepia officinalis"

"their expression (except for Sof_CRY6) undergoes an increase in the eyes from stage 25 to 28 thus confirming their role in the ability of the cuttlefish embryos to perceive light through the egg capsule."

"we studied the temporal expression of these genes in the eyes of embryos from stage 23 to hatching and their expression in two extraocular tissues, skin and central nervous system"

"We showed in embryos that some of these genes (Sof_CRY6, Sof_reti-1, Sof_reti-2, Sof_r-opsin1 and Sof_v-arr) are expressed in the eyes and not in the skin or CNS."

"it seems that some of these genes (Sof_r-opsin1 and Sof_reti1) are used for light detection in these extraocular tissues but that they set-up later in development than in the eyes."

"these families undergo several duplication events in Mollusca: one duplication in the arrestin family and two in the opsin family."

"This study raises the question of the role of Sof_CRY6 in the developing eyes in cuttlefish embryos and the role and localization of xenopsins and r-opsin2."

"cephalopods having the fewest number of opsins and loss of at least 2 major opsin types."

"We found extensive opsin family expansion and contraction, particularly in bivalve xenopsins and gastropod Go-opsins, while other opsins, like retinochrome, rarely duplicate."

"We used molluscan genome assemblies from 80 species to predict protein sequences and examine gene family evolution using phylogenetic approaches."

"some taxa, including cephalopods and terrestrial gastropods, have reduced repertoires of both protein families."

"Photoaffinity labelling by a GTP analogue has been used to identify a 42 kDa band as the major G alpha subunit in squid photoreceptor membranes, recently identified by partial sequence analysis to be a member of the Gq sub-group of GTP-binding proteins"

"Guanine-nucleotide-binding displacement analysis gave a stoichiometry of 1 G-protein per 12.5 rhodopsin molecules, the same as in vertebrate rod photoreceptors. Binding was not detected above background in the dark, but was rapidly activated by light."

"Invertebrate visual signal transduction is initiated by rhodopsin activation of a guanine nucleotide binding protein, Gq, which stimulates phospholipase C (PLC) activity. We have previously purified a 140-kDa PLC enzyme from squid photoreceptors that is regulated by squid Gq."

"an additional PLC enzyme was purified from the cytosol of squid photoreceptors and identified as a 70-kDa protein by SDS-polyacrylamide gel electrophoresis."

"These results suggest that cephalopod phototransduction is mediated by Gq activation of more than one cytosolic PLC enzyme."