Browsing by Subject "photoreceptors"
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Item Biological Sunscreens Tune Polychromatic Ultraviolet Vision in Mantis Shrimp(Elsevier B.V., 2014-07-03) Bok, Michael J.; Porter, Megan L.; Place, Allen R.; Cronin, Thomas W.Stomatopod crustaceans, or mantis shrimp, are renowned for their complex visual systems. Their array of 16 types of photoreceptors provides complex color reception, as well as linear and circular polarization sensitivity. The least-understood components of their retina are the UV receptors, of which there are up to six distinct, narrowly tuned spectral types . Here we show that in the stomatopod species Neogonodactylus oerstedii, this set of receptors is based on only two visual pigments. Surprisingly, five of the six UV receptor types contain the same visual pigment. The various UV receptors are spectrally tuned by a novel set of four short- and long-pass UV-specific optical filters in the overlying crystalline cones. These filters are composed of various mycosporine-like amino acid (MAA) pigments. Commonly referred to as “nature’s sunscreens,” MAAs are usually employed for UV photoprotection , but mantis shrimp uniquely incorporate them into powerful spectral tuning filters, extending and diversifying their preeminently elaborate photoreceptive arsenal.Item Spectral Sensitivity of Vision in the Mantis Shrimp, Gonodactylus oerstedii, Determined Using Noninvasive Optical Techniques(The Biological bulletin, 1989-06-01) Cronin, Thomas W.; King, Christina A.Compound eyes of stomatopod crustaceans have many unique design features. Recently developed intracellular optical physiology techniques permit the measurement of spectral sensitivity functions in intact eyes of these animals. We tested four technically distinct approaches to measurement of spectral sensitivity in peripheral ommatidia of the compound eyes of Gonodactylus oerstedii. Each technique was evaluated for (1) the time required to measure a complete sensitivity spectrum, (2) reproducibility of results, and (3) suitability for use in a fully automated system. A spectral scan technique, in which the visual response is held constant by varying stimulation intensity throughout the scan, was found to be superior. With it, a complete, highly reproducible measurement of spectral sensitivity from 400 to 650 nm at 10-nm intervals could be accomplished automatically within 20 min. The photoreceptors were maximally sensitive near 540 nm, and the sensitivity curve was well described by the absorptance curve for a retinal₁-based visual pigment with peak absorbance at 537 nm and peak density equal to 0.5 OD.Item An Unexpected Diversity of Photoreceptor Classes in the Longfin Squid, Doryteuthis pealeii(PLOS, 2015-09-09) Kingston, Alexandra C. N.; Wardill, Trevor J.; Hanlon, Roger T.; Cronin, Thomas W.Cephalopods are famous for their ability to change color and pattern rapidly for signaling and camouflage. They have keen eyes and remarkable vision, made possible by photoreceptors in their retinas. External to the eyes, photoreceptors also exist in parolfactory vesicles and some light organs, where they function using a rhodopsin protein that is identical to that expressed in the retina. Furthermore, dermal chromatophore organs contain rhodopsin and other components of phototransduction (including retinochrome, a photoisomerase first found in the retina), suggesting that they are photoreceptive. In this study, we used a modified whole-mount immunohistochemical technique to explore rhodopsin and retinochrome expression in a number of tissues and organs in the longfin squid, Doryteuthis pealeii. 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.