Photopigments are found in two places - rods and cones.
Microspectrophotometry studies of other members of the family Pleuronectidae (Platichthys flesus [flounder] and Pseudopleuronectes americanus [winter flounder]) show that the peak absorbance of the
photopigment in rod cells is [approximately equal to] 510 nm, that in single cones is [approximately equal to] 450 nm, and that in double cones is [approximately equal to] 530 or 550 nm (Evans et al.
This, taken together with evidence for extraocular photoreception in the nerve cords of decapods, warrants further investigation into whether the abundance of stomatopod opsin transcripts found in retinas extends to extraretinal tissues and whether they there form functional
photopigments that contribute to a significant physiological role.
The matching range on the red-green mixture scale is highly correlated with the peak wavelength separation of the two expressed
photopigments determined by genetic analysis.
Photopigment markers include chlorophyll b and lutein (chlorophytes), zeaxanthin, myxoxanthophyll, and echinenone (cyanobacteria), fucoxanthin (diatoms), peridinin (dinoflagellates), and alloxanthin (cryptomonads).
This combination of traits is highly suggestive that the transcript produces an apoprotein able to bind to a retinal-based chromophore to form a
photopigment capable of absorbing light.
Trichromatic vision, often described inappropriately as 'red', 'green'and 'blue', is derived from three cone classes which contain
photopigment with relatively long (L), medium (M) and short (S) wavelength spectral sensitivity.
When we blocked the function of ME-ller cells, the retinal visual pathway could not function because cones ran out of
photopigment and could not adapt to dark, Kefalov says.
While recent studies have shown Rh7 expression in retinal or CNS tissues, or ubiquitously in both, they have been unable to determine whether either the Rh7 physiological function or the Rh7
photopigment is sensitive to visible or ultraviolet (UV) wavelengths of light (Battelle et al.
Their cylindrical shape and the orientation of the
photopigment rhodopsin within the rods make them suitable.
It appears that the cones are disturbed and may be diminished in number, or the number of discs in the cone outer segments where the
photopigment is located are decreased in AMD.
The researchers believed that the new
photopigment did not have to establish new neural connections, but an extra dimension of colour vision developed from the splitting of the existing chromatic pathway.
