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  • 1
    Electronic Resource
    Electronic Resource
    Structure of Lathyrine (1962)
    [s.l.] : Nature Publishing Group
    Nature 194 (1962), S. 91-92 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] It is now reported that lathyrine absorbs two molecules of hydrogen when reduced under these conditions, and that the reduced compound has been isolated as a monohydrate m.p. above 250 (decomp.) [〈x]2! + 64-11 in water (c., 1-1). Found: C, 40-87; H, 7-91. C7H14O2N4.H2O requires C, 41-18; H, 7-84 ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/194091a0
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  • 2
    Electronic Resource
    Electronic Resource
    Melanopsin and rod–cone photoreceptive systems account for all major accessory visual functions in mice (2003)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 424 (2003), S. 75-81 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In the mammalian retina, besides the conventional rod–cone system, a melanopsin-associated photoreceptive system exists that conveys photic information for accessory visual functions such as pupillary light reflex and circadian photo-entrainment. On ablation of the melanopsin gene, ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature01761
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  • 3
    Electronic Resource
    Electronic Resource
    A comparison of some photoreceptor characteristics in the pineal and retina (1989)
    Springer
    Journal of comparative physiology 165 (1989), S. 553-563 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunocytochemistry with a rod-specific antiserum was used to study the post-hatch development (2 days–300 days) of photoreceptor elements within the pineal of the Japanese quail. At all ages staining was restricted to limited numbers of pinealocytes scattered throughout the gland. An enzyme-linked immunosorbent assay (ELISA), with the same rod-specific antibody, was then used to obtain a quantitative measure of rod opsin in total eye and pineal extracts in both the developing retina and pineal. The opsin content of both tissues shows a marked increase during the first 30 days after hatch and then plateaued to 0.84±0.02 nmoles opsin in the eye and 2.20±0.11 pmoles opsin equivalents in the pineal. The increase in opsin in the retina may be associated with continued post-hatch development of the photoreceptors. We then attempted to demonstrate the presence of the rhodopsin chromophore within pineal and retinal extracts using HPLC analysis. In both retinal and pineal extracts, 11-cis retinaldehyde was identified and a light-induced shift from the 11-cis to the all-trans isomer was clearly shown. This analysis also allowed us to calculate the total content of 11-cis and all-trans retinaldehyde (derived from both rod and non-rod photoreceptors) of the eye and pineal (eye: 1.7±0.2 nmoles; pineal: 4.6±0.5 pmoles). In the quail eye, the total amount of retinaldehyde is more than twice the amount of rod-like opsin. This probably reflects the large contribution of cones in the quail retina; the cone pigments will contribute to the retinaldehyde content but are not recognized by the rodspecific antibodies. In the pineal, we also found more than double the concentration of retinaldehyde than we would have predicted from the amount of rod-like opsin. These results, coupled with our immunocytochemical findings, suggest that the quail pineal contains at least two classes of photoreceptor, some ‘rod-like’, others ‘non rod-like’.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00611241
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  • 4
    Electronic Resource
    Electronic Resource
    A comparison of some photoreceptor characteristics in the pineal and retina (1989)
    Springer
    Journal of comparative physiology 165 (1989), S. 565-572 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A rod-specific antiserum was used to immunolabel elements within the retina and pineal of the adult Djungarian hamster and Welsh Mountain sheep. In the retina immunostaining was localized to the outer segments and perikarya of photoreceptor cells, while in the pineal limited numbers of labelled pinealocytes were scattered throughout the gland. An enzyme-linked immunosorbent assay (ELISA) was then used to obtain a quantitative measure of rod opsin in total eye and pineal extracts from the Djungarian hamster. Total rod opsin (±SEM) in the eye was measured by absorbance spectroscopy (1.88±0.10 nmoles opsin/eye) and by using the ELISA (1.75±0.02 nmoles opsin/eye). The opsin content from a total of 56 pineals gave a mean value of 0.34±0.01 pmoles opsin/pineal. Since a functional photopigment should be coupled in a 1∶1 ratio to a chromophore, we investigated whether we could identify 11 -cis and/or alltrans retinaldehydes in the pineal extracts by quantitative extraction and HPLC analysis as the oximes. No evidence of 11-cis or all-trans retinaloxime could be found, the chromatograms were indistinguishable from those produced by extracts of cortical brain tissue. We conclude that the opsin present within the adult hamster pineal is not coupled to the common vertebrate retinaldehyde chromophore, and as a result, is unlikely to be part of a functional photopigment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00611242
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  • 5
    Electronic Resource
    Electronic Resource
    Evidence for a daily rhythmicity in the acute release of luteinizing hormone in response to electrical stimulation in the Japanese quail (1987)
    Springer
    Journal of comparative physiology 161 (1987), S. 315-319 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This study was undertaken to examine the effect of electrical stimulation of the hypothalamus at different times of day on luteinizing hormone (LH) secretion in male castrated quail on short days (8L∶16D). The posterior hypothalamus was stimulated with square-wave pulses of 80 μA for 2 min through chronically-implanted platinum microelectrodes. Stimulation was carried out on each quail at 4 (treatment A), 10 (B), or 14 h (C) after dawn. Plasma LH levels were increased markedly within 2 min of ending the stimulation but reached basal levels again over the next 20 min or so. The absolute increase was significantly greater in treatment B (10 h after lights on) than at the other times tested. This is consistent with a rhythm in hypothalamic responsivity. The results are discussed in the context of the rhythm of photoinducibility which occurs early in the night and which is used by quail as a photoperiodic clock to regulate seasonal reproduction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615251
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  • 6
    Electronic Resource
    Electronic Resource
    Circadian photoreception in the retinally degenerate mouse (rd/rd) (1991)
    Springer
    Journal of comparative physiology 169 (1991), S. 39-50 
    Details
    ISSN: 1432-1351
    Keywords: Photoreception ; Retinally degenerate ; Mouse ; Circadian ; Rods ; Cones ; 11-cis retinaldehyde ; Immunocytochemistry ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We have examined the effects of light on circadian locomotor rhythms in retinally degenerate mice (C57BL/6J mice homozygous for the rd allele: rd/rd). The sensitivity of circadian photoreception in these mice was determined by varying the irradiance of a 15 min light pulse (515 nm) given at circadian time 16 and meauring the magnitude of the phase shift of the locomotor rhythm. Experiments were performed on animals 80 days of age. Despite the loss of visual photoreceptors in the rd/rd retina, animals showed circadian responses to light that were indistinguishable from mice with normal retinas (rd/+ and +/+). While no photoreceptor outersegments were identified in the retina of rd/rd animals (80–100 days of age), we did identify a small number of perikarya that were immunoreactive for cone opsins, and even fewer cells that contained rod opsin. Using HPLC, we demonstrated the presence and photoisomerization of the rhodopsin chromophore 11-cis retinaldehyde. The rd/rd retinas contained about 2% of 11-cis retinaldehyde found in +/+ retinas. We have yet to determine whether the opsin immunoreactive perikarya or some other unidentified cell type mediate circadian light detection in the rd/rd retina.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198171
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  • 7
    Electronic Resource
    Electronic Resource
    The involvement of a rhodopsin-like photopigment in the photoperiodic response of the Japanese quail (1985)
    Springer
    Journal of comparative physiology 157 (1985), S. 519-528 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A technique has been developed for the investigation of the photopigment involved in the photoperiodic control of reproduction in Japanese quail,Coturnix coturnix. When these photoreceptors were exposed to white or monochromatic light a clear relationship was found between light intensity and the extent of photo-induced luteinizing hormone (LH) secretion. A spectroradiometric investigation of the passage of light through the skull and brain enabled us to illuminate the hypothalamic region with equal numbers of photons at a range of wavelengths. Action spectra were then conducted and showed a photopigment with a peak sensitivity at wavelengths near 500 nm. An excellent match was obtained when the standard absorption spectrum for a rhodopsin was fitted to the action spectrum, suggesting a rhodopsin maximally sensitive at 492 nm. The absolute sensitivity of the photoreceptors was calculated at a range of wavelengths: with light at 500 nm, 2.85×10−12 μE·cm−2·s−1 triggered the photoperiodic response. This level of sensitivity is matched only by the rhodopsin visual pigments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615153
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  • 8
    Electronic Resource
    Electronic Resource
    Opsin localization and chromophore retinoids identified within the basal brain of the lizard Anolis carolinensis (1993)
    Springer
    Journal of comparative physiology 172 (1993), S. 33-45 
    Details
    ISSN: 1432-1351
    Keywords: Photoreception ; Extraretinal Photoreceptor ; Chromophore ; Opsin ; Reptile ; Immunocytochemistry ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Since the beginning of this century evidence has accumulated which demonstrates that non-mammalian vertebrates possess photoreceptors situated deep within the brain. While many attempts have been made to localize these sensory cells, studies have either failed or been inconclusive. In this report we have used several experimental approaches to localize the deep brain photoreceptors of the lizard Anolis carolinensis. Using 3 antibodies that bind vertebrate cone opsins, we have immunolabelled cerebrospinal fluid (CSF)-contacting neurons located at the ventricular border within the nucleus ventromedialis of the septum. Western blot analysis indicates that these antibodies recognized a single 40 kD protein in ocular, anterior brain, and pineal extracts. Immunoblots of rodent brain did not show a similar protein band. We have also identified specific retinoids associated with phototransduction (11-cis and all-trans-3,4-didehydroretinaldehyde) within anterior brain extracts. This combined data provides the most detailed analysis of deep brain photoreceptors in any vertebrate. Consequently, we feel Anolis provides an excellent model to study this unexplored sensory system of the vertebrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214713
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  • 9
    Electronic Resource
    Electronic Resource
    Thresholds for masking responses to light in three strains of retinally degenerate mice (1999)
    Springer
    Journal of comparative physiology 184 (1999), S. 423-428 
    Details
    ISSN: 1432-1351
    Keywords: Key words Locomotor activity ; Masking ; Retinal degeneration ; Rhythms ; Vision
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Mutant mice with retinal degeneration (rd/rd) were given 1-h pulses of light of varying brightness at times of the night when they would normally be active. The mutant mice showed a significantly greater inhibition of locomotor activity to light (negative masking) than wildtype controls. Lack of impairment, or even enhancement of negative masking suggests that this response may depend on sparing in retinally degenerate mice of the same receptor type that mediates clock resetting, because synchronization of the circadian system is known to be unimpaired in these mutants. With very dim light pulses, mutants did not change their activity, but wildtypes actually became more active (positive masking). Positive and negative masking appear to depend on different sensory and central processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050341
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  • 10
    Electronic Resource
    Electronic Resource
    Rhodopsin-like sensitivity of extra-retinal photoreceptors mediating the photoperiodic response in quail (1985)
    [s.l.] : Nature Publishing Group
    Nature 313 (1985), S. 50-52 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Removing the eyes and/or the pineal gland from Japanese quail does not influence the effects of 'long days' on gonadal maturation2,3. Specifically, illuminating the pineal gland has no effect on the gonads4 but local illumination of the posterior basal hypothalamus leads to gonadal growth, as if ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/313050a0
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