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1.
Red-green cone interactions in the increment-threshold spectral sensitivity of primates 总被引：2，自引：0，他引：2
Threshold spectral sensitivity of primate eyes is the upper envelope of the sensitivity of three response channels. Sensitivity in the green and red channels is modeled as linear difference functions reflecting neural interaction between cones containing photopigments with 535- and 575-nanometer peaks. Sensitivity in the blue channel seems determined by a single class of cones containing a 445-nanometer photopigment. 相似文献
2.
Opponent color cells in the cat lateral geniculate nucleus 总被引：1，自引：0，他引：1
A microelectrode survey of the cat lateral geniculate has uncovered an infrequent new type of lateral geniculate cell in layer B with "on" center responses to short wavelengths and "off" center responses to long wavelengths. The short wavelength responses are mediated by cones with peak sensitivity at about 450 nanometers, and the long wavelength responses by cones with peak sensitivity at 556 nanometers. Two of double opponent color cells also had double opponent features. 相似文献
3.
Lucas RJ Freedman MS Muñoz M Garcia-Fernández JM Foster RG 《Science (New York, N.Y.)》1999,284(5413):505-507
In mammals, ocular photoreceptors mediate an acute inhibition of pineal melatonin by light. The effect of rod and cone loss on this response was assessed by combining the rd mutation with a transgenic ablation of cones (cl) to produce mice lacking both photoreceptor classes. Despite the loss of all known retinal photoreceptors, rd/rd cl mice showed normal suppression of pineal melatonin in response to monochromatic light of wavelength 509 nanometers. These data indicate that mammals have additional ocular photoreceptors that they use in the regulation of temporal physiology. 相似文献
4.
A circadian rhythm of egg hatching in the moth Pectinophora gossypiella can be initiated with a brief light pulse. The action spectrum for this effect has a peak in the blue and near ultraviolet region of the spectrum with a sharp cutoff above 500 nanometers and a more gradual cutoff below 390 nanometers. 相似文献
5.
Spectral measurements of red bioluminescence were obtained from the deep-sea stomiatoid fishes Aristostomias scintillans (Gilbert) and Malacosteus niger (Ayres). Red luminescence from suborbital light organs extends to the near infrared, with peak emission at approximately 705 nanometers in the far red. These fishes also have postorbital light organs that emit blue luminescence with maxima between 470 and 480 nanometers. The red bioluminescence may be due to an energy transfer system and wavelength-selective filtering. 相似文献
6.
7.
The compound eye of the cockroach Periplaneta has receptors for ultraviolet light (maximum sensitivity at 365 nanometers) and green light (maximum sensitivity at 510 nanometers). Single photoreceptor cells in the compound eye were impaled, identified by spectral response, and marked with dye-filled microelectrodes. Using two diferent dyes, we showed that both types of receptors can be found in the same ommatidium. 相似文献
8.
Structural modification of photosynthetic reaction centers is an important approach for understanding their charge-separation processes. An unprecedented persistent structural transformation of the special pair (dimer) of bacteriochlorophyll molecules can be produced by light absorption alone. The nonphotochemical hole-burned spectra for the reaction center of Rhodopseudomonas viridis show that the phototransformation leads to a red shift of 150 wave numbers for the special pair's lowest energy absorption band, P960, and a comparable blue shift for a state at 850 nanometers, which can now be definitively assigned as being most closely associated with the upper dimer component. Additional insights on excited-state electronic structure include the identification of a new state. 相似文献
9.
An unusual phycoerythrin from a marine cyanobacterium 总被引：1，自引：0，他引：1
Phycoerythrin conjugates are reagents for cell sorting and analyses in which the argon-ion laser line at 488 nanometers is used for excitation. Many marine Synechococcus strains contain phycoerythrins with absorption maxima at approximately 490 and 550 nanometers; these maxima indicate the presence of phycourobilin and phycoerythrobilin prosthetic groups in the protein. Phycoerythrins of red algae contain both groups, but those of freshwater and soil cyanobacteria contain only phycoerythrobilin. Phycoerythrin purified from Synechococcus WH8103 has molecular properties typical of red algal phycoerythrins, but its phycourobilin content is higher than that of other phycoerythrins. The protein has absorption maxima at 492 and 543 nanometers and corresponding molar extinction coefficients of 2.78 and 1.14 x 10(6); it fluoresces maximally at 565 nanometers with a quantum yield of 0.5. Conjugates of Synechococcus WH8103 phycoerythrin could increase the sensitivity of cell analysis techniques to almost twice that possible with other phycoerythrin conjugates. 相似文献
10.
The retinal cones of cynomolgus macaque monkeys show marked amounts of adaptation when the receptor potential is elicited by brief incremental stimuli presented against steady backgrounds of increasing intensity. The results can be accounted for by mechanisms of response compression, modified by the effects of photopigment bleaching, which together set the gain of the system at each background level, while also making the response nearly linear over a significant range of intensities above and below that of each adapting stimulus. 相似文献
11.
Spectral tuning of pigments underlying red-green color vision 总被引：18，自引：0，他引：18
Variations in the absorption spectra of cone photopigments over the spectral range of about 530 to 562 nanometers are a principal cause of individual differences in human color vision and of differences in color vision within and across other primates. To study the molecular basis of these variations, nucleotide sequences were determined for eight primate photopigment genes. The spectral peaks of the pigments specified by these genes spanned the range from 530 to 562 nanometers. Comparisons of the deduced amino acid sequences of these eight pigments suggest that three amino acid substitutions produce the approximately 30-nanometer difference in spectral peaks of the pigments underlying human red-green color vision, and red shifts of specific magnitudes are produced by replacement of nonpolar with hydroxyl-bearing amino acids at each of the three critical positions. 相似文献
12.
红蓝单色光质下茄子叶片的光吸收与光合光响应特性 总被引：2，自引：0，他引：2
以日光温室茄子‘黑帅圆茄’为试材,测试了高亮型发光二极管LED光源发出的白光(400~700 nm)和单色光质[红光(650±5)nm、蓝光(470±5)nm]下叶片和叶绿素的光吸收,以及光合对光强响应特性参数的影响,分析了红、蓝单色光质的光合效率。通过分光光度计在400~700 nm波长范围内扫描表明,叶绿素对强吸收波长400~480 nm和650~680 nm范围内的红光(660 nm)和蓝光(470 nm)的吸光值较高,白光(400~700 nm)较低。通过积分球采用LED光源测得红光下茄子叶片的光吸收系数ε最高,其次为白光,蓝光最低。在白光和红、蓝单色LED光源下,光饱和点LSP无明显差异,在1 800~2 000μmol/(m2.s)之间;但是,蓝光的表观光量子效率AQY、实际光量子效率PQY、最大净光合速率Pnmax和最大光合光转化效率LCEmax均比红光的低;蓝光的光补偿点LCP、光半饱和点LSPsemi比红光的高,白光居中。综合反映出蓝光的光合效率低于红光,其原因主要与蓝光的光吸收系数ε低于红光有关。 相似文献
13.
Bradshaw WE 《Science (New York, N.Y.)》1972,175(4028):1361-1362
While 540 nanometers is the most effective wavelength in provoking development, larvae are far more responsive to 540-nanometer light if it is provided immediately preceding rather than followng a white-light photophase which otherwise serves to maintain diapause. This difference in sensitivity is probably due to bleaching and implies that the larvae experience an asymmetric day. 相似文献
14.
Cessation of movement (stop response) is used as a criterion for light reception by the dinoflagellate Gyrodinium dorsum Kofoid. Brief irradiation (2 seconds at 470 nanometers) elicits a stop response in cells any time during the 6-minute interval after removal from growth lights. This stop response is inactivated by exposure for 4 minutes to 470-nanometer light prior to stimulation. Red light (620 nanometers) reactivates this stop response, and far-red light (700 nanometers) reverses this reactivation. This red-far-red photo reversibility is taken as evidence for phytochrome involvement. 相似文献
15.
Panda S Nayak SK Campo B Walker JR Hogenesch JB Jegla T 《Science (New York, N.Y.)》2005,307(5709):600-604
In mammals, a small population of intrinsically photosensitive retinal ganglion cells (ipRGCs) plays a key role in the regulation of nonvisual photic responses, such as behavioral responses to light, pineal melatonin synthesis, pupillary light reflex, and sleep latency. These ipRGCs also express melanopsin (Opn4), a putative opsin-family photopigment that has been shown to play a role in mediating these nonvisual photic responses. Melanopsin is required for the function of this inner retinal pathway, but its precise role in generating photic responses has not yet been determined. We found that expression of melanopsin in Xenopus oocytes results in light-dependent activation of membrane currents through the Galpha(q)/Galpha(11) G protein pathway, with an action spectrum closely matching that of melanopsin-expressing ipRGCs and of behavioral responses to light in mice lacking rods and cones. When coexpressed with arrestins, melanopsin could use all-trans-retinaldehyde as a chromophore, which suggests that it may function as a bireactive opsin. We also found that melanopsin could activate the cation channel TRPC3, a mammalian homolog of the Drosophila phototransduction channels TRP and TRPL. Melanopsin therefore signals more like an invertebrate opsin than like a classical vertebrate rod-and-cone opsin. 相似文献
16.
落叶松球果花蝇的视觉诱捕 总被引：5，自引：4，他引：5
1996年在黑龙江省太兴安岭地区加格达奇附近进行了落叶松球果花蝇（Strobitomyiaspp)的视觉诱捕试验。结果表明．黑胸球果花蝇为该地区的优势种．并首次发现了黄尾球果花蝇进一步探明了该地区落叶松球果花蝇的种团由6种组成。球果花蝇的种团结构及种群的雌雄性比在不同年份，不同林地有变化。挂于树冠上的蓝杯诱辅器诱捕效果优于设在树梢的黄板诱捕器，二者差异显著，挂于树冠南侧的蓝杯请捕器效果明显优于其它三个方位。蓝杯诱捕器对雌雄蝇的诱捕效果因花蝇种群在不同年份的性比变化而有明显差异。 相似文献
17.
A linear photodiode array has been used as the photodetector element in a new ultraviolet-visible detection system for high-performance liquid chromatography. This array allows simultaneous acquisition of light intensity data at all wavelengths between 190 and 600 nanometers. By use of a computer network concept in the electronics, this detection system can process eight different chromatographic signals simultaneously in real time and acquire spectra manually or automatically. Detector response times are variable and can be as low as 0.040 second, and bandwidth selection is variable from 4 to 400 nanometers. These characteristics permit fast chromatographic techniques and user-selectable signal-to-noise ratio enhancement. Spectra can be acquired in 10 milliseconds, permitting qualitative characterization at several different points on a single peak without destroying chromatographic signal integrity. Examples illustrate applications in fast high-performance liquid chromatography peak purity determination, and postanalysis data reduction. 相似文献
18.
Microspectrophotometry of photoreceptor organelles from eyes of the prawn Palaemonetes 总被引：3，自引：0，他引：3
Microspectrophotometric measurements of individual dark-adapted rhabdoms of the prawn Palaemonetes vulgaris reveal the presence of two light-sensitive pigments. A pigment with maximum absorbancy at 555 nanometers is converted by light to a long-lived intermediate with wavelength of maximum absorbancy at 496 nanometers. A second pigment with wavelength of maximum absorbancy at 496 nanometers bleaches in the light, seemingly without forming detectable products at wavelengths longer than 375 nanometers. Both pigments occur in each layer of microvilli. 相似文献
19.
Photosensitivity of the circadian rhythm and of visual receptors in carotenoid-depleted Drosophila 总被引：6，自引：0，他引：6
Drosophila melanogaster was raised on aseptic diets, with and without beta-carotene. The sensitivity of visual receptors in the carotenoid-depleted flies was lowered 3 log units, but the photosensitivity of the circadian rhythm was not affected. This result suggests that the chromophore of the photopigment which mediates light effects on the circadian rhythm is not a carotenoid derivative. 相似文献
20.
The ultraviolet receptor of bird retinas 总被引：4，自引：0，他引：4
The eyes of 15 species of birds from 10 families have some cones maximally sensitive at 370 nanometers in the near-ultraviolet. Spectral sensitivity was measured by recording extracellularly in opened eyecups , and a maximum in the ultraviolet was revealed by selectively adapting the retina with yellow background lights. The 370-nanometer spectral sensitivity function is attributed to receptors because its spectral position does not vary with the strength of adaptation and because it is present when the receptor potentials are isolated from the contributions of higher order retinal neurons by exposing the retina to sodium aspartate. These measurements demonstrate the basis for the ultraviolet sensitivity of birds that has been seen in behavioral experiments, and they provide further evidence that many vertebrates share with insects vision in the near-ultraviolet. 相似文献