Aspects of color vision in bluegill sunfish (Lepomis macrochirus): ecological and evolutionary relevance

Summary Spectral sensitivity curves were measured for bluegills using a heart-rate conditioning technique. A mean spectral sensitivity curve (n=3) determined using a white background exhibited two main peaks, indicating the possible presence of two cone photoreceptors mechanisms. Chromatic adaptation was used to separate the contribution of the cone mechanisms to sensitivity. Peak sensitivities were located at 540 and 640 nm against red and blue-green backgrounds, respectively.Light adaptation curves were measured for each cone mechanism indicating that these cone mechanisms have their greatest contrast sensitivity at higher background intensities. Spatial summation properties were also measured for each cone mechanism revealing a critical diameter (summation area) of 5° for both mechanisms.Microspectrophotometric (MSP) measurements were made on individuals from the same group of bluegills used in the above experiments. The results showed the presence of two cone types: single green-sensitive cones with an average _max of 536 nm (SD±1.8nm,n=11) and twin redsensitive cones with an average _max of 620 nm (SD ±1.9 nm,n=11).The correlation between the visual pigment absorption spectra and action spectra of the two cone mechanisms indicate a sound physiological basis for sensitivity. The functional properties of the two cone mechanisms, will be discussed in relation to the ecological and behavioral aspects of bluegills.Abbreviation TVI threshold vs intensity     

Spectral absorption and sensitivity measurements in single ommatidia of the green crab,Carcinus

Summary Rhabdoms of the green crabCarcinus maenas were examined by microspectrophotometry and found to contain a visual pigment with _max at 502–506 nm. Upon irradiation, a stable metarhodopsin formed with unchanged _max and molar extinction coefficient. In the presence of 5% glutaraldehyde the rhabdoms were photobleached. Partial bleaching experiments indicate that in the rhabdoms studied, only one visual pigment was present, with an absorption spectrum appropriate for a hypothetical rhodopsin from Dartnall's (1953) nomogram.Retinular (photoreceptor) cells were studied with microelectrodes. They had negative resting potentials of 30–65 mV and responded to light with depolarizing receptor potentials. All cells had maximum sensitivity at ~493 nm, as did the ERG (electroretinogram). Selective adaptation failed to alter the spectral sensitivity functions of single cells or the ERG. If these spectral sensitivity data are pooled with Wald's (1968), the average sensitivity of the dark-adapted eye is accounted for adequately by the pigment of the rhabdom.The results of this work do not support the hypothesis of Horridge (1967) that each ommatidium ofCarcinus has two color receptors.This work was supported by U.S. P.H.S. grant EY 00222.     

Spectral and polarized light sensitivity of photoreceptors in the compound eye of the cricket (Gryllus bimaculatus)

Summary Retinula cells in the compound eye of the cricket (Gryllus bimaculatus) were recorded intracellularly and stained with Lucifer yellow. Two different methods were used to determine the spectral sensitivity of these cells: a) the spectral scanning method, and b) the conventional flash method. Three spectral types, with S()-curves close to the rhodopsin-absorption functions, were found with _max at 332 nm (UV), 445 nm (blue) and 515 nm (green), respectively.Blue receptors were only recorded in the anatomically specialized dorsal rim area (DRA), and UV and green receptors in the dorsal region of the pigmented part of the eye, whereby green receptors were only found in the ventral eye. On the basis of these results, model calculations are presented for di- and trichromatic colour vision in the cricket.The fluorescence markings revealed green receptors whose axons project with short visual fibres to the lamina, and a UV receptor with a long visual fibre which projects through the lamina to the medulla. The blue receptors send their axons either to the lamina and medulla (long visual fibres) or only to the lamina (short visual fibres).The temporal dynamics of the three receptor types were examined. The blue receptors lack a phasic component of the receptor potential, and the time from stimulus on-set to peak potential is strongly increased compared to the UV and green receptors. Light adaptation reduces the latency to less than half of the dark adapted state.Spectral adaptation experiments revealed an unidirectional coupling between UV and green receptors, and it was found that polarization sensitivity (PS) in blue cells was much higher (PS= 6.5±1.5) than that of UV (PS=1.76±0.05) and green (2.26±0.57) receptors. The functional aspects of the three receptor types are discussed with respect to the presented physiological and morphological data.Abbreviations DA dorsal area - DRA dorsal rim area - PS polarization sensitivity     

Intracellular responses from the photosensitive pineal organ of the teleost,Phoxinus phoxinus

Summary Intracellular potentials from the isolated dark-adapted pineal organ ofPhoxinus phoxinus were recorded by using glass microelectrodes. The majority of cells had resting potentials of 20 to 35 mV and responded to light with intensitygraded hyperpolarizations. Voltage intensity curves of responses to brief flashes followed the hyperbolic tangent functionV/V _max=Iⁿ/(I ⁿ + ⁿ ).The latency of onset for responses to light stimuli near threshold was 400 ms and decreased with saturating flashes to about 50 ms. The membrane resistance decreased during the hyperpolarization. Spectral sensitivity measurements for these cells exhibited curves with _max=530 nm. Intracellular dye injection unequivocally identified this cell type as a photoreceptor cell.A second cell type with resting potentials between 30 to 40 mV exhibited a biphasic response pattern to light stimulation. The cell depolarized with dim light flashes and hyperpolarized with bright flashes. The amplitude of the hyperpolarizing component showed no saturation over an intensity range of 5 log units. Latencies and rise times were comparable to those of photoreceptor potentials. Spectral sensitivity curves peaked at longer wavelengths ( _max=550 nm) than the action spectra of photoreceptors ( _max=530 nm). It is assumed that this rare cell type represents a small class of pineal interneurons.     

Spectral sensitivity of photoreceptors in insect compound eyes: Comparison of species and methods

Summary Three different methods were used to determine the spectral sensitivity of retinula cells in the compound eyes of three species of hymenopteran insects (Apis mellifera, Melipona quadrifasciata, Osmia rufa). The conventional flash method gives the least reliable results. Sensitivity is extremely sensitive to small fluctuations of the resting potential and long lasting changes induced by preceding test flashes. The ramp method, which speeds up a spectral scan to about 1 min and keeps effective illumination constant at every flash, determines S() much more reliably. The best results are obtained with the spectral scan method, which provides the experimenter with aS() function of high spectral resolution within 20 s. Using this method we demonstrate that the high observed variability inS() of individual receptors is the result of the inadequacy of the flash method, which was the only method used in earlier studies.Double microelectrode experiments and variations of the stimulus conditions reveal that field potentials and return flow of electric current produced by activated neighboring cells have no effect in the bee eye. We conclude that the model of Shaw (1975, 1981) of current flow in the locust and fly eye does not apply to the bee eye. Very rare recordings (about 1%) of UV receptors with hyperpolarizing responses to long wavelength light are interpreted as having a synaptic inhibitory connection to green receptors.The improvement of spectral measurements of single receptors allows us for the first time to model the spectral input to a color-coding network with great precision.     

Visual and lenticular pigments in the eyes of demersal deep-sea fishes

We report on the lens pigmentation and visual pigments of 52 species of demersal deep-sea fishes caught at depths ranging from 480 m to 4110 m in the Porcupine Seabight and Goban Spur area of the North-eastern Atlantic. Only one species, caught between 480 and 840 m, had a lens with large amounts of pigment, consistent with the hypothesis that heavily pigmented lenses in deep-sea fish serve to enhance the contrast of bioluminescent signals by removing much of the background radiance, which is only visible to fish living shallower than 1000 m. Low concentrations of lens pigmentation were also observed in a further two species (Rouleina attrita and Micromesisteus poutassou). The retinae of all species except five, contained only a single visual pigment, as determined by microspectrophotometry of individual rods, and/or spectrophotometry of retinal wholemounts and retinal extracts. Those fishes caught between 500 m and 1100 m had wavelengths of peak sensitivity (_max) ranging from 476 nm to 494 nm, while most fish living below 1100 m tended to be more conservative with (_max) values ranging from 475 nm to 485 nm. The only exceptions to this were three deep-living species caught between 1600 m and 2000 m whose retinae contain abnormally short-wave sensitive visual pigments (Cataetyx laticeps — _max 468 nm; Alepocephalus bairdii — _max 467 nm; Narcetes stomias _max 472 nm), suggesting adaptation for the detection of short-wave bioluminescence.     

Intraspecific variation of spectral sensitivity in threespine stickleback (Gasterosteus aculeatus) from different photic regimes

To examine the influence of the spectral characteristics of underwater light on spectral sensitivity of the ON and OFF visual pathways, compound action potential recordings were made from retinal ganglion cells of threespine stickleback from different photic regimes. In fish from a red-shifted photic regime (P₅₀ 680 nm for downwelling light at 1m), peak sensitivity of both the ON and OFF pathways was limited to long wavelength light (_max 600–620). In contrast, the ON pathway of fish from a comparatively blue-shifted (P₅₀ 566 nm) photic regime exhibited sensitivity to medium (_max 540–560) and long (_max 600 nm) wavelengths, while the OFF pathway exhibited peak sensitivity to only medium (_max 540 nm) wavelength light. In a third population, where the the ambient light is moderately red-shifted (P₅₀ 629 nm), the ON pathway once again exhibited only a long wavelength sensitivity peak at 620 nm, while the OFF pathway exhibited sensitivity to both medium (_max 560 nm) and long (_max 600–620 nm) wavelength light. These findings suggest that the photic environment plays an integral role in shaping spectral sensitivity of the ON and OFF pathways.     

Action spectra for changes in the “high irradiance reaction” in hypocotyls of Sinapis alba L.

Detailed action spectra are presented for the inhibition of hypocotyl extension in dark-grown Sinapis alba L. seedlings by continuous (24 h) narrow waveband monochromatic light between 336 nm and 783 nm. The results show four distinct wavebands of major inhibitory action; these are centred in the ultra-violet (_max=367 nm), blue (_max=446 nm), red (_max=653 nm) and far-red (_max=712 nm) wavebands. Previous irradiation of the plants with red light (which also decreases Ptot) causes decreased inhibitory action by all wavelengths except those responsible for the red light inhibitory response. Pre-irradiation did not alter the wavelength of the action maxima. It is concluded that ultra-violet and blue light act mainly on a photoreceptor which is different from phytochrome.Abbreviations B blue - D dark - FR far-red - HIR high irradiance reaction - HW half power bandwith - Pr R absorbing form of phytochrome - Pfr FR absorbing form of phytochrome - Ptot total phytochrome=Pr+Pfr - R red - UV ultra violet     

Microspectrophotometry of the photoreceptors of palaeognathous birds — the emu and the tinamou

Summary With the aid of a microspectrophotometer the visual pigments and oil globules in the retina of the emu (Dromiceius novae-hollandiae), the brushland tinamou (Nothoprocta c. cinerascens) and the Chilean tinamou (Nothoprocta perdicaria sanborni) were characterized. All three of these palaeognathous birds contain in their rods a typical rhodopsin with _max near 500 nm. Each of these birds has cones containing iodopsin-like visual pigments with _max in the 560–570 nm spectral region. No unequivocal evidence was obtained for the presence of cone pigments other than this iodopsin-like pigment, although one cell thought to be a cone, and containing a visual pigment with _max near 498 nm, was observed in the retina of the brushland tinamou. The oil globule systems of the three palaeognathous species are identical to each other and are much simpler than is typical for neognathous birds in that only two different types of globule are present, one with _T50 at 508 nm and another with _T50 at 568 nm. Comparison of the data with observations made on neognathous species indicates (1) that palaeognathous birds probably have poorer color discrimination capabilities than neognathous birds and (2) that the tinamou is more closely related to the ratites than to the galliform species.This study was supported, in part, by NIH Grant No. EY01839 (A.J. Sillman), NIH Grant No. EY00323 (W.N. McFarland) and NSF Grant No. 78-07657 (E.R. Loew). The authors thank E. Clinite, R. Dunford, C. Murphy, R. Riis and D. Weathers for their valuable assistance. Thanks also go to R.E. Burger for his gift of the emus.     

Increment-threshold spectral sensitivity in the rabbit

Summary Increment threshold measurements in wild rabbits give rise to spectral sensitivity curves that are unimodal or bimodal in nature, depending on the background luminance. We propose a model that explains the shape of these curves on the basis of synergistic and antagonistic interaction of blue cones (_max = 425 nm), green cones (_max = 523 nm) and rods (_max = 498 nm).     

Microspectrophotometric characterization and localization of three visual pigments in the compound eye ofNotonecta glauca L. (Heteroptera)

Summary The absorption maxima ( _max) of the visual pigments in the ommatidia ofNotonecta glauca were found by measuring the difference spectra of single rhabdomeres after alternating illumination with two different adaptation wavelengths. All the peripheral rhabdomeres contain a pigment with an extinction maximum at 560 nm. This pigment is sensitive to red light up to wavelengths > 700 nm. In a given ommatidium in the dorsal region of the eye, the two central rhabdomeres both contain one of two pigments, either a pigment with an absorption maximum in the UV, at 345 nm, or — in neighboring rhabdoms — a pigment with an absorption maximum at 445 nm. In the ventral part of the eye only the pigment absorbing maximally in the UV was found in the central rhabdomeres. The spectral absorption properties of various types of screening-pigment granules were measured.     

Purification and initial characterization of phycobiliproteins from the endophytic cyanobacterium of Azolla

The endophytic cyanobacterium, Anabaena azollae, isolated from laboratory cultures of Azolla caroliniana Willd., contains three spectroscopically distinct biliproteins. About 70% of the biliprotein is c-phycocyanin (_max 610 nm) and 13% is allophycocyanin (_max 647 nm, shoulder 620 nm). A third pigment corresponds to phycoerythrocyanin (_max 570 nm, shoulder 590 nm). In very dilute solutions of allophycocyanin, at constant pH and buffer strength, the 647 nm maximum disappears and a single _max occurs at 615–620 nm. The 647 nm absorption maximum reappears upon concentrating the dilute solution. Very dilute solutions of phycoerythrocyanin exhibit a broad peak between 570 and 590 nm. Absorption spectra of c-phycocyanin are not significantly altered upon dilution. Fluorescence emission maxima of phycoerythrocyanin, c-phycocyanin, and allophycocyanin occur at 630 nm, 643 nm and 660 nm respectively, using 540 nm excitation. Two subunits, of molecular weight 16,500 () and 20,600 (), are seen in c-phycocyanin upon dissociation with SDS. Dissociation of allophycocyanin and phycoerythrocyanin with SDS yields one sizeclass of subunits, with a molecular weight of about 17,500 for allophycocyanin and 18,000 for phycoerythrocyanin.Contribution No. 684 Offprint requests to: G. A. Peters     

Photoreceptor optics of the honeybee and its eye colour mutants: the effect of screening pigments on the long-wave subsystem of colour vision

With the aim of clarifying the role of screening pigments in photoreceptor optics of the compound eye, a comparative study of the optical properties of the honeybee eye in the visible region of the spectrum was carried out using wild-type bees and eye colour mutantssnow, snow ^laranja, ivory^umberandchartreuse with total or partial blockage of the tryptophane-ommochrome pathway.

Photopigments of the lateral eye ofLimulus

Summary Photoreceptor membrane fractions of the lateral eye ofLimulus were solubilized in the detergent emulphogene, and three photobleachable materials were observed with respective _max values at 330nm±10nm, 450 nm±10 nm, and 530 nm±10 nm. A530 is the pigment which had been reported earlier by Hubbard and Wald (1960), and it can be separated from A330 and A450 on the basis of differential solubility in digitonin. Approximately the same number of incident quanta were required for a unit absorbance change at _max for all three pigments, but measurable photo-products were not observed after bleaching A330 and A450.We thank Daniel Inners for discussion and Thomas Wheeler and Vivian Leitner for assistance. This work was supported by NSF grants GB-33499 and BMS 75-07197, NIH grants EY-00871 and EY-00244, and The Institute of Ophthalmology, Houston. We also thank I.L. and Bertha Gordon Miller for their generous gift of the Cary 118C.     

The properties of photoreconvertible fluorophore systems in insect eyes resemble those of quinones

Summary Photoreconvertible fluorophore systems were found in the superposition compound eyes of the mothDeilephila and the neuropterAscalaphus. The systems are very similar to those first described by Schlecht et al. (1987) on the apposition eye of the blowflyCalliphora. The fluorophore systems in the cone cells ofDeilephila andAscalaphus closely agree with those in the Semper cells ofCalliphora. In all 3 species the primary fluorophore is converted by UV into a blue-absorbing fluorophore with its _max in the range between 410 and 450 nm. The intensity of the fluorescence from the photoproducts in all 3 pigment systems is highly dependent on pH; maximal intensity is recorded if pH5. The pK point is at 6.0 (Deilephila). The fluorescence from the Semper cells (and rhabdomeres) inCalliphora is maximal at low retinoid content showing that the chromophoric group of the fluorophore systems is not a retinoid. The probable candidates for the chromophoric group in these systems are quinones, like ubiquin-one. Phospholipid vesicles into which ubiquinone has been incorporated have fluorophore characteristics comparable to those of the fluorophores in the compound eyes: photoreconversion is induced by UV and blue light, the excitation maxima of the primary and secondary fluorophore are similar, and the intensity of the fluorescence from the secondary fluorophore is highly dependent on pH. The intensity of the fluorescence from the vesicles also depends on the direction of the pH gradient across the membrane, suggesting that this pH dependence is due to an asymmetric distribution of the quinone rings at the inner and outer membrane surface.     

Microspectrophotometry of the visual pigment of the spider crab Libinia emarginata

Summary Isolated dark-adapted rhabdoms from the spider crab Libinia emarginata were examined by microspectrophotometry to determine the visual pigments present and their light-sensitive characteristics. The rhabdoms contain a single pigment with _max=493 nm. Upon one minute irradiation with bright orange light this pigment forms a light-stable photoproduct with nearly the same _max as the parent pigment but with slightly greater absorption to the long wavelength side of the absorption peak. On exposure to orange or yellow light in the presence of 5% glutaraldehyde, however, the pigment of Libinia rhabdoms bleaches slowly.The photosensitive pigment of properly oriented, transversely illuminated rhabdoms shows isotropic and dichroic regions, corresponding to layers of the rhabdom in which the microvilli are respectively parallel and perpendicular to the direction of propagation of the measuring beam. The maximum dichroic ratio is about 2, with most absorption when the plane of polarization is parallel to the microvillar axes.

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Zusammenfassung Die isolierten, dunkeladaptierten Rhabdome von Libinia emarginata wurden mikrospektrophotometrisch untersucht, um die Sehfarbstoffe und ihre lichtempfindlichen Eigenschaften zu entdecken. Die Rhabdome enthalten ein einziges Pigment (_max 493 nm). Nach einer Bestrahlungszeit von 1 min mit hellem orangem Licht entsteht ein lichtfestes Photoprodukt mit beinahe dem gleichen _max wie das ursprüngliche Pigment, aber mit etwas größerer Absorption gegen die langwellige Seite des Absorptionsmaximums hin. Das Pigment von Libinia-Rhabdomen bleicht langsam aus, wenn man es orangem oder gelbem Licht in Gegenwart von 5% Glutaraldehyd aussetzt.Werden richtig orientierte Rhabdome von der Seite belichtet, so zeigt das lichtempfindliche Pigment teils Isotropismus teils Dichroismus. Im ersten Fall sind die Mikrovilli parallel zur Richtung des Meßstrahles orientiert, im zweiten Fall stehen sie senkrecht dazu. Das größte Dichroismus-Verhältnis liegt bei 2. Man erhält die größte Absorption, wenn die Polarisationsrichtung parallel zur Achse der Mikrovilli steht.

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This work was supported by U.S.P.H.S. grant NB-03333. Some of the experiments were done at The Marine Biological Laboratory, Woods Hole, Mass.     

The spectral input systems of hymenopteran insects and their receptor-based colour vision

Summary Spectral sensitivity functions S() of single photoreceptor cells in 43 different hymenopteran species were measured intracellularly with the fast spectral scan method. The distribution of maximal sensitivity values (_max) shows 3 major peaks at 340 nm, 430 nm and 535 nm and a small peak at 600 nm. Predictions about the colour vision systems of the different hymenopteran species are derived from the spectral sensitivities by application of a receptor model of colour vision and a model of two colour opponent channels. Most of the species have a trichromatic colour vision system. Although the S() functions are quite similar, the predicted colour discriminability curves differ in their relative height of best discriminability in the UV-blue or bluegreen area of the spectrum, indicating that relatively small differences in the S() functions may have considerable effects on colour discriminability. Four of the hymenopteran insects tested contain an additional R-receptor with maximal sensitivity around 600 nm. The R-receptor of the solitary bee Callonychium petuniae is based on a pigment (P596) with a long _max, whereas in the sawfly Tenthredo campestris the G-receptor appears to act as filter to a pigment (P570), shifting its _max value to a longer wavelength and narrowing its bandwidth. Evolutionary and life history constraints (e.g. phylogenetic relatedness, social or solitary life, general or specialized feeding behaviour) appear to have no effect on the S() functions. The only effect is found in UV receptors, for which _max values at longer wavelengths are found in bees flying predominantly within the forest.     

The respiratory chain of the facultative thermophile,Bacillus coagulans

Two oxidases were found to be present in membranes from the facultative thermophile Bacillus coagulans grown at 55°C, compared to one in cells grown at 37°C. Cytochrome spectra and inhibitors of the respiratory chain identified them as cytochrome oxidases aa ₃ and d. Both were present in membranes from 55°C grown cells, but only cytochrome oxidase aa ₃ was found in membranes from 37°C grown cells. The presence of cytochrome d in 55°C grown cultures was found to be due to decreased oxygen tension and not to the high growth temperature. This was confirmed by (a) induction of cytochrome d at 37°C under conditions of oxygen limitation and (b) its repression at 55°C under conditions of high aeration and its subsequent induction on lowering the dissolved oxygen concentration in chemostat cultures. Two cytochromes b (_max 558 and _max 562) were present in both 37°C and 55°C grown cells. Results from the inhibition of substrate oxidation by membranes suggested different pathways of electron transport by the respiratory chain.