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  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 393 (1998), S. 423-424 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Most deep-sea fish have visual pigments that are most sensitive to wavelengths around 460-490 nm, the intensity maxima of both conventional blue bioluminescence and dim residual sunlight. The predatory deep-sea dragon fish Malacosteus niger, the closely related Aristostomias sp. and ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 191 (1961), S. 266-267 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The proper interpretation of such observations clearly depends on an understanding of the characteristics (as radar targets) of hail, both wet and dry. Recent computations by Herman and Bafctan2 and measurements by Atlas et al.3 have shed light on the problem of radar scatter by hail (particularly ...
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 49 (1996), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Three goldfish were trained to search for food buried 20 cm from a perspex tower. In the absence of food, all fish still searched in the correct location, revealing that fish can use a landmark to locate food. Halving either the width or height of the landmark resulted in searches significantly closer to the tower, suggesting that fish determined their position relative to the landmark using its horizontal and vertical visual angles.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 31 (1987), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Photoreceptor loss causes irreversible blindness in many retinal diseases. Repair of such damage by cell transplantation is one of the most feasible types of central nervous system repair; photoreceptor degeneration initially leaves the inner retinal circuitry intact and new photoreceptors ...
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  • 6
    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, ...
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 50 (1997), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The retinal visual pigments of 52 species of deep-sea fish were measured by partial bleaching of detergent extracts. The retinae of 45 species contained only a single rhodopsin with maximum absorbance (λmax) at a wavelength between 474 and 490 nm, matching both the region of highest intensity downwelling sunlight and the maximum emission of most deep-sea bioluminescence. Seven species were shown to have more than one visual pigment within their retinae and these had λmax values that generally fell outside the usual range. One of these, Bonapartia pedaliota, was particularly interesting as, unlike most such multipigment species, it had one rhodopsin and one porphyropsin pigment, apparently based on different opsins. The relative proportions of the visual pigments in the seven multipigment species are presented.
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  • 8
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. In order to analyse the mechanism of accommodation in anurans, drugs (miotic or atropine) were applied to the cornea of anaesthetized animals to change the refractive state of their eyes. During such changes, the lens and cornea were photographed and the refractive state of the eye was measured using laser speckle refractometry. Measurements taken from the photographs confirmed suggestions by Beer (1898) that accommodation is achieved by moving the lens and not by changing the shape of the lens or cornea. The change in refractive state induced by pharmacological manipulation was about 10 diopters with an accompanying shift in lens position of about 150 μm. Calculations based on a schematic eye suggest a disparity between the amount of lens movement theoretically needed to produce a 10 D shift in refractive state and the amount actually observed. 2. The lens is probably moved by two protractor lentis muscles which are positioned so as to pull the lens towards the cornea (Tretjakoff 1906, 1913). Dissection and HRP preparations revealed that these muscles are innervated by fibres of the oculomotor nerve which relay in the ciliary ganglion. InR. esculenta andR. pipiens, the ciliary ganglion consists of only 8 to 12 nerve cells. 3. MS222 anaesthesia and lymphatic injection of curare cause the lens to move away from the cornea, presumably because they destroy the resting tonus of the protractor lentis muscles. We discuss this finding in relation to the frog's ‘resting’ accommodative state, and conclude that unparalysed frogs are likely to be myopic, and not emmetropic as previous work suggests. 4. Prey capture was analysed inR. pipiens after the disruption of accommodation by bilateral section of the oculomotor nerve. Estimates of prey distance remained accurate when vision was binocular. However, during monocular vision, when the oculomotor nerve was sectioned on one side and the other eye was either occluded or had its optic nerve cut, frogs consistently underestimated the distance of their prey. This result suggests, in agreement with earlier evidence, that accommodation is used for judging depth when vision is limited to one eye, but that binocular information predominates when it is available. 5. Atropine applied to the cornea of monocular frogs also causes distance to be underestimated. It is argued from this that frogs assess distance by monitoring the motor commands sent to their accommodative muscles, rather than by using sensory information from the muscles themselves.
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  • 9
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This study reports photopic spectral sensitivity curves (351–709 nm) for four individual roach,Rutilus rutilus, determined by two choice appetitive training. All four curves show four sensitivity maxima at 361–398 nm, 421–448 nm, 501–544 nm and 634–666 nm which are related to the four known roach photopic visual pigments (Avery et al. 1982). The overall shape of the curves at long wavelengths indicates inhibitory interactions between the red and green cone mechanisms. That the high behavioural sensitivity in the UV is caused by a specific ultraviolet visual pigment and is not due to aberrant stimulation of the other cone types is shown by the redetermination of spectral sensitivity at short wavelengths (351–501 nm) following the selective bleaching of the three longer wavelength visual pigments. This depresses the blue sensitivity to a greater degree than the relatively unaffected UV sensitivity maximum. Spectral transmission data from two corneas and four lenses show that they transmit considerable amounts of light in the near UV.
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  • 10
    ISSN: 1432-1351
    Keywords: Deep-sea Fish ; Visual pigments ; Lenses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 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 (λmax) ranging from 476 nm to 494 nm, while most fish living below 1100 m tended to be more ‘conservative’ with (λmax) 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 — λmax 468 nm; Alepocephalus bairdii — λmax 467 nm; Narcetes stomias λmax 472 nm), suggesting adaptation for the detection of short-wave bioluminescence.
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