Color Blindness Research Today is a free monthly online journal that collates and summarizes the latest research about Color Blindness, including details on causes, classification, red-green and blue-yellow color blindness, diagnosis.

Immunohistochemical evidence for multiple photosystems in box jellyfish.

Ekström P, Garm A, Pålsson J, Vihtelic TS, Nilsson DE

Department of Cell and Organism Biology, Zoology Building, Lund University, Helgonavägen 3, S-223 62, Lund, Sweden, Peter.Ekstrom@cob.lu.se.

Cubomedusae (box jellyfish) possess a remarkable visual system with 24 eyes distributed in four sensory structures termed rhopalia. Each rhopalium is equipped with six eyes: two pairs of pigment cup eyes and two unpaired lens eyes. Each eye type probably captures specific features of the visual environment. To investigate whether multiple types of photoreceptor cells are present in the rhopalium, and whether the different eye types possess different types of photoreceptors, we have used immunohistochemistry with a range of vertebrate opsin antibodies to label the photoreceptors, and electroretinograms (ERG) to determine their spectral sensitivity. All photoreceptor cells of the two lens eyes of the box jellyfish Tripedalia cystophora and Carybdea marsupialis displayed immunoreactivity for an antibody directed against the zebrafish ultraviolet (UV) opsin, but not against any of eight other rhodopsin or cone opsin antibodies tested. In neither of the two species were the pigment cup eyes immunoreactive for any of the opsin antibodies. ERG analysis of the Carybdea lower lens eyes demonstrated a single spectral sensitivity maximum at 485 nm suggesting the presence of a single opsin type. Our data demonstrate that the lens eyes of box jellyfish utilize a single opsin and are thus color-blind, and that there is probably a different photopigment in the pigment cup eyes. The results support our hypothesis that the lens eyes and the pigment cup eyes of box jellyfish are involved in different and specific visual tasks.

Published 18 June 2008 in Cell Tissue Res, 333(1): 115-24.
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Articles on Color Blindness published 13 June 2008:

Pupillary responses to coloured and contourless displays in total cerebral achromatopsia.   Brain.

In two patients with total acquired cortical colour blindness and in six control subjects we studied the binocular pupillary response to a variety of sharply defined coloured and grey displays that either had the same mean luminance as the background (isoluminant) or were of greater mean luminance. Despite their complete inability to identify or to discriminate between colours the patients, like the control subjects, showed a pupillary response to the structured coloured displays, even when ... [Abstract] [Full-text]

Articles on Color Blindness published 29 May 2008:

Fear of the mind. The annihilating power of the gaze.   Am J Psychoanal, 68(2): 169-76.

The concern for the annihilating power of the gaze is not part of the Freudian discourse, but represents one of the most valuable contributions of phenomenology to psychoanalysis. When clear boundaries between the self and the others are not yet established, the gaze is experienced as a disembodied force that radiates from the eyes and can dangerously penetrate into the mind. In this regard, the body or parts of it can be used as a shelter. If the external body is not sufficiently cathected, ... [Abstract] [Full-text]

Articles on Color Blindness published 23 May 2008:

Adverse cardiovascular effects of acute salt loading in young normotensive individuals.   Hypertension, 51(6): 1525-30.

We sought to explore the effects of salt loading in young normotensives on vascular endothelial function, echocardiographic left ventricular diastolic function, and electrocardiographic QT dispersion. Sixteen healthy normotensive male volunteers were randomized in a double-blind crossover fashion to 5-day treatment periods with either placebo or salt tablets (200 mmol/d of sodium) separated by a 2-week washout period. Throughout the study the volunteers were asked to maintain a low-salt diet. ... [Abstract] [Full-text]

Articles on Color Blindness published 14 May 2008:

Color matching on natural substrates in cuttlefish, Sepia officinalis.   J Comp Physiol A Neuroethol Sens Neural Behav Physiol, 194(6): 577-85.

The camouflaging abilities of cuttlefish (Sepia officinalis) are remarkable and well known. It is commonly believed that cuttlefish-although color blind-actively match various colors of their immediate surroundings, yet no quantitative data support this notion. We assembled several natural substrates chosen to evoke the three basic types of camouflaged body patterns that cuttlefish express (uniform/stipple, mottle, and disruptive) and measured the spectral reflectance of the camouflaged pattern ... [Abstract] [Full-text]

Articles on Color Blindness published 12 May 2008:

Summary of: An in vitro comparison of tooth whitening techniques on natural tooth colour.   Br Dent J, 204(9): 516-517.

Objective Tooth whitening has become a popular treatment regime but there is little quantitative evidence to compare techniques and so confusion may exist for the clinician as to which regime to prescribe for greatest efficacy. The aim of this study was to compare immediate and longer-term colour change on natural tooth colour in vitro, using five current tooth whitening techniques with blind matched control groups.Methods A total of 100 human teeth of matched size were cleaned, stored in ... [Abstract] [Full-text]

An in vitro comparison of tooth whitening techniques on natural tooth colour.   Br Dent J, 204(9): E15; discussion 516-7.

OBJECTIVE: Tooth whitening has become a popular treatment regime but there is little quantitative evidence to compare techniques and so confusion may exist for the clinician as to which regime to prescribe for greatest efficacy. The aim of this study was to compare immediate and longer-term colour change on natural tooth colour in vitro, using five current tooth whitening techniques with blind matched control groups. METHODS: A total of 100 human teeth of matched size were cleaned, stored in ... [Abstract] [Full-text]

Articles on Color Blindness published 8 May 2008:

Different ranking of avian colors predicted by modeling of retinal function in humans and birds.   Am Nat, 171(6): 831-8.

Abstract: Only during the past decade have vision-system-neutral methods become common practice in studies of animal color signals. Consequently, much of the current knowledge on sexual selection is based directly or indirectly on human vision, which may or may not emphasize spectral information in a signal differently from the intended receiver. In an attempt to quantify this discrepancy, we used retinal models to test whether human and bird vision rank plumage colors similarly. Of 67 species, ... [Abstract] [Full-text]

Articles on Color Blindness published 30 April 2008:

Functional analysis of human CNGA3 mutations associated with colour blindness suggests impaired surface expression of channel mutants A3(R427C) and A3(R563C).   Eur J Neurosci, 27(9): 2391-401.

Mutations in the CNGA3 gene have been associated with complete and incomplete forms of total colour blindness (achromatopsia), a disorder characterized by reduced visual acuity, lack of colour discrimination, photophobia and nystagmus. CNGA3 encodes the A-subunit of the cone photoreceptor cyclic nucleotide-gated (CNG) channel, an essential component of the phototransduction cascade. Here we report the identification of three new CNGA3 mutations in patients with achromatopsia. To assess the ... [Abstract] [Full-text]

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