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  • 1
    Electronic Resource
    Electronic Resource
    ON THE VISUAL SYSTEM OF THE BEE (APIS MELLIFERA) (1958)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 74 (1958), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1958.tb39547.x
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  • 2
    Electronic Resource
    Electronic Resource
    The Epoxide Nature of the Carotenoid, Neoxanthin (1960)
    [s.l.] : Nature Publishing Group
    Nature 188 (1960), S. 491-493 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Neoxanthin is characterized by: (1) its tight adsorption on chromatographic columns of magnesium oxide or aluminum oxide, where it is found above lutein, violaxanthin, and flavoxanthin; (2) its characteristic absorption spectrum, similar in shape and position to violaxanthin, and with more ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/188491b0
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  • 3
    Electronic Resource
    Electronic Resource
    The interpretation of intracellular measurements of membrane potential, resistance, and coupling in cells of higher plants (1978)
    Springer
    Planta 143 (1978), S. 267-274 
    Details
    ISSN: 1432-2048
    Keywords: Cells (electric properties) ; Coleoptiles ; Electrical parameters ; Intercellular coupling ; Intracellular recording ; Membrane resistance ; Microelectrodes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Results of microelectrode impalements of parenchymal cells of coleoptiles made in several different laboratories differ widely. The highest membrane potentials correlate with lower input resistance and the presence of intercellular coupling, whereas high input resistance seems to be associated with an absence of measurable coupling and possibly lower membrane potentials. In this paper we demonstrate that these results are consistent with (1) a tonoplast resistance several times greater than the input resistance of the cytoplasmic compartment, and (2) the presence of variable amounts of shunting introduced by insertion of the microelectrode through the cell membranes. The general consequences of this hypothesis are developed quantitatively. If the ideas are applicable to other tissues of higher plants-and on this point the evidence is still insufficient to judgeboth the design of experiments and the interpretation of measurements made with microelectrodes will have to be reevaluated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391997
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  • 4
    Electronic Resource
    Electronic Resource
    Spectral responses of sustaining fibers in the optic tracts of crayfish (Procambarus) (1970)
    Springer
    Journal of comparative physiology 69 (1970), S. 117-133 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Spectral response curves were recorded for 60–70 individual sustaining fibers in the optic nerve of the crayfish Procambarus. These cells belong to at least 8 of the 14 classes of sustaining fibers described by Wiersma and Yamaguchi (1966) on the basis of receptive fields. About 90 percent of the cells receive predominant input from yellow-green receptors and are maximally sensitive at 560 to 570 nm; a much smaller number receive principal input from blue receptors and are maximally sensitive near 460 nm. The wavelength sensitivity of optic fibers receiving their major input from yellow-green receptors depends on the state of dark adaptation of the animal and the intensity of illumination. Early in dark adaptation and at high intensities of stimulation the spectral response curve is distorted by light which has been filtered through the sleeves of red-brown shielding pigment. During dark adaptation a shift in maximum spectral response to shorter wavelengths parallels the retraction of the migratory pigment to the “dark” position and the development of retinal glow. The effects are reversed by injecting into a dark-adapted animal an extract of eyestalks containing the hormone controlling pigment migration: the pigment sleeves lengthen, retinal glow disappears, and shoulders or peaks of sensitivity appear in the red region of the spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00340913
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  • 5
    Electronic Resource
    Electronic Resource
    Spectral absorption and sensitivity measurements in single ommatidia of the green crab,Carcinus (1973)
    Springer
    Journal of comparative physiology 82 (1973), S. 151-163 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Rhabdoms of the green crabCarcinus maenas were examined by microspectrophotometry and found to contain a visual pigment with λmax at 502–506 nm. Upon irradiation, a stable metarhodopsin formed with unchanged λmax 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696150
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  • 6
    Electronic Resource
    Electronic Resource
    Microspectrophotometry of the visual pigment of the spider crab Libinia emarginata (1969)
    Springer
    Journal of comparative physiology 65 (1969), S. 218-232 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: 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 (λmax 493 nm). Nach einer Bestrahlungszeit von 1 min mit hellem orangem Licht entsteht ein lichtfestes Photoprodukt mit beinahe dem gleichen λmax 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.
    Notes: 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 λmax=493 nm. Upon one minute irradiation with bright orange light this pigment forms a light-stable photoproduct with nearly the same λmax 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297684
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  • 7
    Electronic Resource
    Electronic Resource
    Comparative studies of crustacean spectral sensitivity (1968)
    Springer
    Journal of comparative physiology 60 (1968), S. 156-175 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Spectral sensitivity of the lateral eyes of the isopodPorcellio scaber (wood louse) and the decapodsCallinectes sapidus (blue crab),Palaemonetes paludosus (Everglades prawn),Orconectes virilis, andO. immunis (crayfish) have been measured between 300 and 660 nm by determining the reciprocal number of photons required to evoke a constant size retinal action potential. Porcellio is maximally sensitive at 515 nm andCallinectes at 505 nm. Both species have a single pigment system, as spectral sensitivity is unchanged by red light adaptation. Palaemonetes appears to have a dichromatic color vision. Sensitivity of the dark-adapted eye is dominated by a receptor maximally sensitive at 550–555 nm, but red or yellow adaptation discloses a uv pigment with λmax at about 380 nm. Present evidence suggests the 555 and 380 nm pigments are located in different receptor cells. Orconectes has peak sensitivity at 565 nm, but under red light adaptation and close to the electroretinographic threshold a second sensitivity maximum appears at 425 nm. As in the prawn, these peaks seem to indicate the presence of a two-receptor color vision system. The corneas ofOrconectes, Callinectes, andHomarus (lobster) are relatively thick, and microspectrophotometric measurements show near ultraviolet absorption as well as the protein peak at 280 nm. By contrast,Palaemonetes andMusca (housefly), species with near ultraviolet receptors, have thinner corneas which are transparent through the near ultraviolet. The crystalline cone ofPalaemonetes likewise shows no near ultraviolet absorption but a strong protein band at 280 nm. The scarcity of ultraviolet receptors in the compound eyes of crustacea, in contrast to their common occurrence in insects, is thought to be related to the relative absence of ultraviolet wavelengths in most aquatic environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00878449
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  • 8
    Electronic Resource
    Electronic Resource
    Photoinhibition of arousal in the stick insect Carausius (1972)
    Springer
    Journal of comparative physiology 76 (1972), S. 135-145 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. The phasmid Carausius assumes a stick posture (thanatosis) during the day but becomes active and feeds at night. Animals placed in darkness during the day start to arouse after a latency of 8–10 minutes, and about half are active after 12 minutes. 2. Light inhibits arousal. A flux of 4×109 hν sec-1 cm−2 at 483 nm increases the latency to the first arousal to about 12 minutes and the half-time to about 26 minutes. 3. The action spectrum for the inhibition of arousal peaks at 510–520 nm. Sensitivity falls gently toward the blue, more steeply to longer wavelengths, and is down 2 log units at 620 nm. 4. Animals with opaque screens on their eyes arouse quickly when placed in dim test lights that inhibit activity in normal controls. Therefore the eyes are the principal receptors. 5. Animals with eyes surgically removed show residual sensitivity to light. Therefore a higher-threshold, extra-optic receptor is also present. 6. Normally the insects integrate intensity over large areas of the visual field, for if they are placed on a reflecting substrate, illumination of the posterior half of the body is as effective in inhibiting arousal as light on the anterior end.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00455958
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  • 9
    Electronic Resource
    Electronic Resource
    Separation of tonoplast and plasma membrane potential and resistance in cells of oat coleoptiles (1982)
    Springer
    The journal of membrane biology 66 (1982), S. 15-23 
    Details
    ISSN: 1432-1424
    Keywords: plant cells ; Avena ; vacuolar membrane ; plasmalemma ; membrane potential ; membrane resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Membrane potential and resistance were recorded from parenchymal cells of oat (Avena) coleoptiles, using one and two intracellular electrodes. Membrane potential is largest (−100 mV) in impalements with low input resistance (2–4 MΩ), and is less negative (−50 mV) in penetrations with high input resistance (〉 20 mΩ). The interpretation is that the electrode lodges in the vacuole which is positive to the cytoplasm (but still negative to the external solution), and that measurements of net membrane potential are compromised to varying degrees by leakage shunts introduced across the high resistance vacuolar membrane by the electrode. This conclusion is supported by several additional lines of evidence. (1) It is possible to convert large-R/small-V impalements into small-R/large-V penetrations by passing excess current through the electrode or by briefly ‘ringing’ the capacitance neutralization circuit in the amplifier. The cells usually recover their resistance in a few minutes, with a concomitant decrease in the negativity of the membrane potential. (2) Changes in external [K] affect the measuree potential by an amount that is independent of the input resistance of the impalement. This is consistent with an effect of [K] o on the potential of the plasma membrane and the occurrence of leakage shunts primarily at the tonoplast. (3) Quantitatively, the effects of a change in [K] o on resistance indicate that nearly 90 percent of the input resistance of unshunted cells resides in the tonoplast. (4) The effects of metabolic inhibitors (DNP, CN−) on potential are smaller in large-R than in small-R impalements. This observation suggests there are electrogenic pumps contributing to the membrane potential at both the plasmalemma and tonoplast. Finally, we conclude that with an electrode in the vacuole it is possible to record potentials that are dominated by the contribution of the plasma membrane, provided care is taken to select impalements combining both large, negative potential and low input resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01868478
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  • 10
    Electronic Resource
    Electronic Resource
    Discrimination of colors by the black-chinned hummingbird,Archilochus alexandri (1979)
    Springer
    Journal of comparative physiology 130 (1979), S. 209-220 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The color vision of a population of black-chinned hummingbirds was studied by behavioral methods. Birds were attracted to feeders equipped with tungsten lamps and interference filters. Results are based on counts of approximately 5700 visits by 92 ± 5 birds. Population size was estimated by mistnetting and marking 29 hummingbirds, 22 of which could be recognized individually during the course of the experiments. Following experience with red (620 nm) at all feeders, the birds showed a modest tendency to visit red (620 nm, 650 nm) and blue (490 nm) rather than intermediate greens and yellows. When sugar was presented at only one wavelength, however, choices became much sharper. When positions of the feeders were randomized, trained birds selected feeders on the basis of hue. Brightness was not used as a significant cue. This finding thus provides a more rigorous demonstration of color vision in hummingbirds than has heretofore been available. Either position or color could be learned in several hours (6–22 visits). Red (620 nm) and green (546 nm) were learned at the same rate. Two different (and opposing) color associations could be learned simultaneously at sites approximately 30 m apart. Discrimination of hue was measured following training to each of four wavelengths: 620, 590, 546, and 480 nm. Light from interference filters with transmission maxima at 546 and 550 nm were differentiated by the birds to a statistically significant extent. 546 and 590 nm appear to lie near the boundaries of hues; a boundary near 540 nm is found in pigeon but not human color vision.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00614607
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