Light has a substantial effect on the behaviour and physiology of nocturnal moths. Ectropis grisescens is a major nocturnal tea pest in China, and light traps are commonly used to control geometrid moths because of their positive phototaxis. However, some moths gather around light traps and enter the light adaptation state, which decreases the efficacy of light traps in controlling this pest. We identified opsin genes and the spectral sensitivities of the photoreceptors of E. grisescens moths. We also determined the effects of several monochromatic lights on opsin gene expression and light adaptation. We detected three types of opsin genes and six spectral sensitive peaks (at 370, 390, 480, 530, 550, and 580 nm). We also observed significant changes in the diurnal rhythm of opsin gene expression under different light conditions. When active males were suddenly exposed to different monochromatic lights, they quickly entered the light adaptation state, and the adaptation time was negatively correlated with the light intensity. Males were most sensitive to 390 nm wavelengths, followed by 544 nm, 457 nm, and 593 nm. Red light (627 nm) did not affect the activity of E. grisescens males but had detectable physiological effects.

There are four cone morphologies in zebrafish, corresponding to UV (U), blue (B), green (G), and red (R)-sensing types; yet genetically, eight cone opsins are expressed. How eight opsins are physiologically siloed in four cone types is not well understood, and in larvae, cone physiological spectral peaks are unstudied. We use a spectral model to infer cone wavelength peaks, semisaturation irradiances, and saturation amplitudes from electroretinogram (ERG) datasets composed of multi-wavelength, multi-irradiance, aspartate-isolated, cone-PIII signals, as compiled from many 5- to 12-day larvae and 8- to 18-month-old adult eyes isolated from wild-type (WT) or roy orbison (roy) strains. Analysis suggests (in nm) a seven-cone, U-360/B1-427/B2-440/G1-460/G3-476/R1-575/R2-556, spectral physiology in WT larvae but a six-cone, U-349/B1-414/G3-483/G4-495/R1-572/R2-556, structure in WT adults. In roy larvae, there is a five-cone structure: U-373/B2-440/G1-460/R1-575/R2-556; in roy adults, there is a four-cone structure, B1-410/G3-482/R1-571/R2-556. Existence of multiple B, G, and R types is inferred from shifts in peaks with red or blue backgrounds. Cones were either high or low semisaturation types. The more sensitive, low semisaturation types included U, B1, and G1 cones [3.0–3.6 log(quanta·μm−2·s−1)]. The less sensitive, high semisaturation types were B2, G3, G4, R1, and R2 types [4.3-4.7 log(quanta·μm−2·s−1)]. In both WT and roy, U- and B- cone saturation amplitudes were greater in larvae than in adults, while G-cone saturation levels were greater in adults. R-cone saturation amplitudes were the largest (50–60% of maximal dataset amplitudes) and constant throughout development. WT and roy larvae differed in cone signal levels, with lesser UV- and greater G-cone amplitudes occurring in roy, indicating strain variation in physiological development of cone signals. These physiological measures of cone types suggest chromatic processing in zebrafish involves at least four to seven spectral signal processing pools.

The zebrafish photopic electroretinogram (ERG) sums isolatable elements. In each element, red-, blue-, green-, and UV- (r, g, b, and u) cone signals combine in a way that reflects retinal organization. ERG responses to monochromatic stimuli of different wavelengths and irradiances were recorded on a white rod suppressing background using superfused eyecups. Onset elements were isolated with glutamatergic blockers and response subtractions. CNQX-blocked ionotropic (AMPA/kainate) glutamate receptors; l-AP4 or CPPG-blocked metabotropic (mGluR6) glutamate receptors; TBOA-blocked glutamate transporters; and l-aspartate inactivated all glutamatergic mechanisms. Seven elements emerged: photopic PIII, the l-aspartate-isolated cone response; b1, a CNQX-sensitive early b-wave element of inner retinal origin; PII, a photopic, CNQX-insensitive composite b-wave element from ON bipolar cells; PIIm, an l-AP4/CPPG-sensitive, CNQX-insensitive, metabotropic subelement of PII; PIInm, an l-AP4/CPPG/CNQX-insensitive nonmetabotropic subelement of PII; a1nm, a TBOA-sensitive, CNQX/l-AP4/CPPG-insensitive, nonmetabotropic, postphotoreceptor a-wave element; and a2, a CNQX-sensitive a-wave element linked to OFF bipolar cells. The first five elements were fit with a spectral model that demonstrates independence of cone–color pathways. From this, Vmax and half-saturation values (k) for the contributing r-, g-, b-, and u-cone signals were calculated. Two signal patterns emerged. For PIII or PIInm, the Vmax order was Vr > Vg >> Vb ≈ Vu. For b1, PII, and PIIm, the Vmax order was Vr ≈ Vb > Vg > Vu. In either pattern, u-cone amplitude (Vu) was smallest, but u-cone sensitivity (ku362) was greatest, some 10–30 times greater than r cone (kr570). The spectra of b1/PII/PIIm elements peaked near b- and u-cone absorbance maxima regardless of criteria, but the spectra of PIII/PIInm elements shifted from b- toward r-cone absorbance maxima as criterion levels increased. The greatest gains in Vmax relative to PIII occurred for the b- and u-cone signals in the b1/PII/PIIm b-wave elements. This suggests a high-gain prolific metabotropic circuitry for b- and u-cone bipolar cells.

R1–6 dominated electroretinographic (ERG) spectral sensitivities were determined as a function of days posteclosion from carotenoid deprived and replaced white-eyed Drosophila. The sensitivity of flies deprived from egg to adult waxed (about 1.5 log units by day 3), and then waned gradually from 3–11 days (over 2 log units by day 11). Carotenoid replacement (feeding nothing but carrot juice) effected recovery to near the replete control' level in about 1 day throughout (tested at 0, 4, and 11 days). The normal yellow cornmeal-agar-molasses-brewers yeast fly food (in our laboratory, supplemented with β-carotene) renders a slower recovery (requiring 7–9 days) since it is a medium designed largely for larval growth. Placing replete adults on deprivational medium did not create a deprivational syndrome in over 11 days. At 3–7 days, deprived flies reared and maintained in constant darkness had substantially enhanced sensitivity, beyond the 1.5 log unit increment already described for cyclic light rearing conditions. All spectral analyses are consistent with the ultraviolet (UV) sensitization of the blue (480 nm) rhodopsin by a replacement-dependent retinoid including two unexpected findings: (1) sensitivity recovery with carrot juice was so fast that the UV peak was already high at 6 h; and (2) the waxing of the deprived fly's sensitivity in dark rearing was so great that the UV peak was present at 4–7 days.

To test the hypothesis that light-evoked cone contraction in eye cups from Xenopus laevis is controlled through a direct mechanism initiated by the cone's own photopigment, we conducted spectral-sensitivity experiments. We estimate that initiation of contraction of red absorbing cones (611 nm) is 1.5 log units more sensitive to green (533 nm) than red (650 nm) light stimuli. The difference is comparable to that predicted from the spectral-sensitivity function of the green absorbing, principal rod (523 nm). Furthermore, 480-nm and 580-nm stimuli which are absorbed nearly equally by the principal rod have indistinguishable effects on cone contraction. We also found that light blockade of nighttime cone elongation is much more sensitive to green than to red light stimuli. Our observations are inconsistent with the hypothesis tested, and suggest that light-regulated cone motility is controlled through an indirect mechanism initiated primarily by the green absorbing, principal rod.

In a dichromatic teleost species, we determined the intensity of light of various wavelengths required to prevent cone elongation by exposing fish at the time of their normal “dusk” phase to monochromatic light (479, 623, and 660 nm) at eight to ten different intensities for 75 min. The positions of single and double cones were measured in tangential sections and expressed as cone indices. At all wavelengths, the spectral responses of both cone types were virtually identical. Furthermore, the sensitivity of the blocking effect was highest at shorter wavelengths. When comparing the relative quantal sensitivities of myoid elongation for the two cone types to the spectral sensitivities of the three types of Aequidens pulcher photoreceptor, we found the closest match between the action spectrum and the absorption spectrum of the green-sensitive single cones. This may indicate that this cone type is capable of reacting directly to decreasing levels of illumination. On the other hand, the identical sensitivity of both cone types argues for an indirect control mechanism of dark-adaptive cone elongation, possibly via a neural pathway involving the inner retinal layers, complementary to the neural control of light adaptation. Green-sensitive single cones are well suited to trigger this response, since (1) their sensitivity is inferior to that of double cones; (2) waters inhabited by the blue acara transmit best at long wavelengths; and (3) at dusk, long-wavelength radiation dominates over other parts of the spectrum. Therefore, green-sensitive cone threshold will be reached first at dusk.

Visual information encoded by the middle-wavelength-sensitive (MWS) and long-wavelength-sensitive (LWS) cones in the primate retina are processed by both depolarizing (ON) and hyperpolarizing (OFF) bipolar cells. In contrast, signals from the short-wavelength-sensitive (SWS) cones and dark-adapted rod photoreceptors are thought to be carried almost exclusively by ON bipolar cells (Gouras & Evers, 1985). Consequently, it would be expected that functional inactivation of the retinal ON channels at the bipolar cell level would produce selective deficits in visual functions mediated by rods and SWS cones. We have examined this hypothesis by injecting rhesus monkeys with 2-amino-4-phosphonobutyric acid (APB), a pharmacological agent that reduces the responsiveness of retinal ON neurons, and psychophysically measuring the changes in spectral sensitivities. Under adaptation conditions that isolated rod function, APB caused, as expected, a substantial loss in rod-mediated spectral sensitivity. However, under photopic conditions, cone-mediated spectral sensitivity, including that associated with the SWS cones, was relatively unaffected. These results demonstrate distinct organizational differences between the rod and cone systems; specifically, they indicate that the rod system is more dependent upon retinal ON channels than the cone system. Our failure to find a selective visual deficit related to SWS cone function under photopic viewing conditions suggests that the OFF system can mediate stimulus detection throughout the visible spectrum and that the ability of the OFF system to process signals from the SWS cones has been underestimated.

Psychophysical studies have documented that many observers show lower thresholds for rapid-off than for rapid-on sawtooth luminance modulation. This finding, together with physiological findings from chromatically opponent ganglion cells of the macaque monkey, prompted a search for a similar bias in psychophysical detection of chromatic increments and decrements of light. Using a luminance pedestal in conjunction with a luminance background to favor detection by chromatic mechanisms, we measured spectral sensitivity for rapid-on and rapid-off sawtooth stimuli presented spatially coextensive with the pedestal. There were two different pedestal chromaticities: one broadband, and the second composed only of long-wavelength light to enhance short-wavelength-sensitive, cone-mediated detection. Spectral-sensitivity measurements for different wavelength stimuli revealed no systematic differences across the visible spectrum as a function of sawtooth waveform polarity or pedestal chromaticity. Similarly, temporal contrast-sensitivity functions for hetero-chromatically modulated red-green sawtooth stimuli did not reveal an asymmetry in sensitivity for rapid-red and rapid-green chromatic change. Some of the observers showed a higher sensitivity for luminance modulated rapid-off sawtooth stimuli, as also noted in previous studies. This asymmetry was not found when a white luminance pedestal and background was used. These results suggest that the cone inputs to chromatically opponent ON- and OFF-center cells are sufficiently balanced to provide equivalent psychophysical thresholds for chromatic increments and decrements of light.

Microelectrodes were used to record from red and green cones of the turtle Pseudemys scripta elegans. The purpose of this study was to determine the action spectra of the red and green cone photopigments, and to look closely for direct interactions between the two cone classes. An isolated retina preparation was employed so that cones could be stimulated from the outer segment side, thereby avoiding the oil droplets that reside in the inner segments of many cones and normally filter incident light. In agreement with some previous electrophysiological studies, we found little evidence for significant direct connections between red and green cones. Exceptions to this rule are noted and discussed. Measurements indicate that this result does not appear to be due to a general loss of cone connectivity in the isolated retina preparation. Action spectra of the cone photopigments differed markedly from action spectra reported for cones in the eyecup preparation. In contrast to cones in the eyecup, cones in the isolated retina showed higher short-wavelength sensitivity and had action spectra that were adequately described by photopigment nomograms. A model of cone optical properties suggests that in the eyecup up to about 40% of the light that reaches a cone outer segment may do so without first passing through an oil droplet.

Macaque monkeys are widely used as a model species for investigations of the biology of human vision. Previous measurements suggest that the cone-based spectral sensitivity of these two primates is greatly similar, but perhaps not identical. We measured the photopic spectral sensitivity of 42 male macaque monkeys from two species (Macaca mulatto, M. fascicularis) using an objective index, electroretinogram flicker photometry. The variations among individuals and between the two species were very small and there was no evidence for any significant cone pigment polymorphism in this sample. There are small but systematic differences in spectral sensitivity between macaque monkeys and equivalently tested human subjects–the monkeys were slightly more sensitive to short wavelengths (<520 nm) and slightly less sensitive to wavelengths longer than this value. The results obtained from the curve fitting of standard photopigment absorption spectra to the spectral-sensitivity functions suggest that the difference between human and macaque monkey spectral sensitivity principally reflects differences in the relative proportions of the long- and middle-wavelength cones in the retinas of the two species.

The action spectrum of the ERG b-wave was measured under dark-adapted conditions in intact goldfish (Carassius auratus). It is substantially broader than the absorption spectrum of goldfish rod porphyropsin. Neither prolonged dark adaptation nor removal of possible efferent neural activity affected its shape. Moreover, a 682-nm background did not produce a selective loss of sensitivity to long wavelengths. The results imply that the spectral sensitivity of the b-wave in dark-adapted goldfish reflects the influence of at least two photoreceptor types which act as a single univariant mechanism near absolute threshold.

The spectral sensitivities of rods and cones in macaque and human retinas were determined by recording the membrane current from single outer segments. In the macaque retina, the wavelengths of maximum sensitivity were at about 430, 530, and 561 nm for the blue, green, and red cones, respectively, and at 491 nm for the rods. The shapes of the spectra of the three cones were similar when plotted on a log wavenumber scale; the rod spectrum was slightly broader. Spectral sensitivities of the red and green cones from a human retina were virtually identical to those of macaque cones. For comparison with human psychophysical measurements, the rod and cone spectra were adjusted to give the sensitivities expected for light incident on the cornea of the human eye. These functions satisfactorily predicted the scotopic and photopic luminosity functions as well as results from human color-matching experiments. The adjusted spectra of the red and green cones also agreed well with the π-mechanisms of Stiles (1953, 1959).

The reports of rod-dominated psychophysical spectral sensitivity from the deprived eye of monocularly lid-sutured (MD) monkeys are intriguing but difficult to reconcile with the absence of any reported deprivation effects in retina. As most studies of MD retina have been from cat, we have examined psychophysically the increment threshold spectral sensitivity of MD cats using both reaction time and simultaneous two-choice behavioral procedures. Although the deprived eyes exhibited an absolute increment threshold sensitivity deficit, both rod and cone spectral sensitivity functions were obtained on large white backgrounds. This normal transition from rod to cone vision, as background luminance increased, was also found in threshold vs. intensity functions. Using their deprived eye, some cats exhibited a rod spectral sensitivity function when a smaller, normally photopic, background was used providing some support for a hypothesis that the rod-dominated spectral sensitivity observed in monkey may represent detection of scattered stimulus light. Alternatively monocular deprivation may reveal a rod-dominated mechanism which exists in monkey but not in cat.

Afterpotentials of A-type horizontal cells (HCs) are believed to be rod-induced. They are, however, complex potentials and evidently of multiple causation. That part of the HC potential immediately after light-off is not entirely rod-determined because it has the same spectral sensitivity as the response to light-on, which is cone-induced with only some rod influence. It persists during a strong blue adapting light, which suppresses rod activity. The afterpotential may also be influenced by feedback from HCs to photoreceptors. The later part of the afterpotentials of A-type HCs is, however, rod dominated, as are the afterpotentials of axon terminals of B-type HCs.

Paradoxical shifts in human color (spectral) sensitivity occur on deep-red (658 nm) background fields. As the radiance of the deep-red background is increased from low to moderate levels, the spectral sensitivity for detecting 15-Hz flicker shifts toward shorter wavelengths, although by more than is predicted by selective chromatic adaptation (e.g., Eisner & MacLeod, 1981; Stromeyer et al., 1987; Stockman et al., 1993). Remarkably, though, at higher background radiances, the spectral sensitivity then shifts precipitously back towards longer wavelengths. Here, we show that both effects are due in large part to destructive and constructive interference between signals generated by the same cone type. Contrary to the conventional model of the human visual system, the M- and L-cone types contribute not just the customary fast signals to the achromatic or luminance pathway, but also slower signals of the same or opposite sign. The predominant signs of the slow M- and L-cone signals change with background radiance, but always remain spectrally opposed (M-L or L-M). Consequently, when the slow and fast signals from one cone type destructively interfere, as they do near 15 Hz, those from the other cone type constructively interfere, causing the paradoxical shifts in spectral sensitivity. The shift in spectral sensitivity towards longer wavelengths is accentuated at higher temporal frequencies by a suppression of fast M-cone signals by deep-red fields.

The dorso-laterally located eyes of the southern hemisphere lamprey Mordacia mordax (Agnatha) contain a single morphological type of retinal photoreceptor, which possesses ultrastructural characteristics of both rods and cones. This photoreceptor has a large refractile ellipsosome in the inner segment and a long cylindrical outer segment surrounded by a retinal pigment epithelium that contains two types of tapetal reflectors. The photoreceptors form a hexagonal array and attain their peak density (33,200 receptors/mm2) in the ventro-temporal retina. Using the size and spacing of the photoreceptors and direct measures of aperture size and eye dimensions, the peak spatial resolving power and optical sensitivity are estimated to be 1.7 cycles deg−1 (minimum separable angle of 34′7′′) and 0.64 μm2 steradian (white light) and 1.38 μm2 steradian (preferred wavelength or λmax), respectively. Microspectrophotometry reveals that the visual pigment located within the outer segment is a rhodopsin with a wavelength of maximum absorbance (λmax) at 514 nm. The ellipsosome has very low absorptance (<0.05) across the measured spectrum (350–750 nm) and probably does not act as a spectral filter. In contrast to all other lampreys studied, the optimized receptor packing, the large width of the ellipsosome-bearing inner segment, together with the presence of a retinal tapetum in the photophobic Mordacia, all represent adaptations for low light vision and optimizing photon capture.

Effects of temperature on the spectral properties of visual pigments were measured in the physiological range (5–28°C) in photoreceptor cells of bullfrog (Rana catesbeiana) and crucian carp (Carassius carassius). Absorbance spectra recorded by microspectrophotometry (MSP) in single cells and sensitivity spectra recorded by electroretinography (ERG) across the isolated retina were combined to yield accurate composite spectra from ca. 400 nm to 800 nm. The four photoreceptor types selected for study allowed three comparisons illuminating the properties of pigments using the dehydroretinal (A2) chromophore: (1) the two members of an A1/A2 pigment pair with the same opsin (porphyropsin vs. rhodopsin in bullfrog “red” rods); (2) two A2 pigments with similar spectra (porphyropsin rods of bullfrog and crucian carp); and (3) two A2 pigments with different spectra (rods vs. long-wavelength-sensitive (L-) cones of crucian carp). Qualitatively, the temperature effects on A2 pigments were similar to those described previously for the A1 pigment of toad “red” rods. Warming caused an increase in relative sensitivities at very long wavelengths but additionally a small shift of λmax toward shorter wavelengths. The former effect was used for estimating the minimum energy required for photoactivation (Ea) of the pigment. Bullfrog rod opsin with A2 chromophore had Ea = 44.2 ± 0.9 kcal/mol, significantly lower (one-tailed P < 0.05) than the value Ea = 46.5 ± 0.8 kcal/mol for the same opsin coupled to A1. The A2 rod pigment of crucian carp had Ea = 42.3 ± 0.6 kcal/mol, which is significantly higher (one-tailed P < 0.01) than that of the L-cones in the same retina (Ea = 38.3 ± 0.4 kcal/mol), whereas the difference compared with the bullfrog A2 rod pigment is not statistically significant (two-tailed P = 0.13). No strict connection between λmax and Ea appears to exist among A2 pigments any more than among A1 pigments. Still, the A1 → A2 chromophore substitution in bullfrog opsin causes three changes correlated as originally hypothesized by Barlow (1957): a red-shift of λmax, a decrease in Ea, and an increase in thermal noise.

The morphology and spectral absorption characteristics of the retinal photoreceptors in the southern hemisphere lamprey Geotria australis (Agnatha) were studied using light and electron microscopy and microspectrophotometry. The retinae of both downstream and upstream migrants of Geotria contained two types of cone photoreceptor and one type of rod photoreceptor. Visual pigments contained in the outer segments of these three photoreceptor types had absorbance spectra typical of porphyropsins and with wavelengths of maximum absorbance (downstream/ upstream) at 610/616 nm (long-wavelength-sensitive cone, LWS), 515/515 nm (medium-wavelength-sensitive cone, MWS), and 506/500 nm (medium-wavelength-sensitive rod). A “yellow” photostable pigment was present in the myoid region of all three types of photoreceptor in the downstream migrant. The same short-wavelength-absorbing pigment, which prevents photostimulation of the beta band of the visual pigment in the outer segment, was present in the rods and LWS cones of the upstream migrant, but was replaced by a large transparent ellipsosome in the MWS cones. Using microspectrophotometric and anatomical data, the quantal spectral sensitivity of each photoreceptor type was calculated. Our results provide the first evidence of a jawless vertebrate, represented today solely by the lampreys and hagfishes, with two morphologically and physiologically distinct types of cone photoreceptors, in addition to a rod-like photoreceptor containing a colored filter (a cone-like characteristic). In contrast, all other lampreys studied thus far have either (1) one type of cone and one type of rod, or (2) a single type of rod-like photoreceptor.

Temperature effects on spectral properties of the two types of rod photoreceptors in toad retina, “red” and “green” rods, were studied in the range 0–38°C. Absorbance spectra of the visual pigments were recorded by single-cell microspectrophotometry (MSP) and spectral sensitivities of red rods were measured by electroretinogram (ERG) recording across the isolated retina. The red-rod visual pigment is a usual rhodopsin (λmax = 503.6 nm and 502.3 nm at room temperature (21°C) in, respectively, Bufo marinus and Bufo bufo), that of green rods (λmax = 432.6 nm in Bufo marinus) belongs to the “blue” cone pigment family. In red rods, λmax depended inversely and monotonically on temperature, shifting by −2.3 nm when temperature was raised from 0°C to 38°C. Green-rod λmax showed no measurable dependence on temperature. In red rods, warming caused a relative increase of sensitivity in the long-wavelength range. This effect can be used for estimating the energy needed for photoexcitation, giving Ea = 44.3 ± 0.6 kcal/mol for Bufo marinus rhodopsin and 48.8 ± 0.5 kcal/mol for Bufo bufo rhodopsin. The values are significantly different (P < 0.001), although the two rhodopsins have very similar absorption spectra and thermal isomerization rates. Our recording techniques did not allow measurement of the corresponding effect at long wavelengths in green rods. Although spectral effects of temperature changes in the physiological range are small and of little significance for visual function, they reveal information about the energy states and different spectral tuning mechanisms of the visual pigments.

We investigated the photocurrents from isolated rods of the South American anuran, Caudiverbera caudiverbera. Rod outer segments were on average 66.4 ± 11.2 μm (mean ± S.D., n = 104) in length and 6.6 ± 0.9 μm (mean ± S.D.) in diameter; 40 ± 22 photoisomerizations (mean ± S.D., range 10–99, n = 16) were required for eliciting a half-saturating photocurrent response. The time-to-peak was 911 ± 217 ms (mean ± S.D., n = 14, 20°C) in the linear range of the response and the integration time of the current response was 1744 ± 451 ms (mean ± S.D., n = 14). The time-to-peak appears to be slower and the integration time shorter in Caudiverbera than in Ambystoma tigrinum, Rana pipiens or Xenopus laevis rods under similar experimental conditions. The α-band of rod spectral sensitivity has a λmax at 520 ± 2.1 nm (mean ± S.D., range 516–525 nm, n = 24) and the bandwidth fits a porphyropsin visual pigment. The single-event response amplitude ranges from 0.31–0.51 pA, depending on the calculation method. The intrinsic dark current (variance at dark minus variance under bright light) was 0.045 ± 0.040 pA2 (mean ± S.D., n = 24). Our results support the presence of a dark-noise component below 1 Hz, with kinetics similar to the single-photon evoked response and a rate of 0.006 events s−1 (n = 9).