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At least 595 records · Page 33Linked to original sources
PubMed2003

Molecular evolution of bat color vision genes.

The two suborders of bats, Megachiroptera (megabats) and Microchiroptera (microbats), use different sensory modalities for perceiving their environment. Megabats are crepuscular and rely on a well-developed eyes and visual pathway, whereas microbats occupy a nocturnal niche and use acoustic orientation or echolocation more than vision as the major means of perceiving their environment. In view of the differences associated with their sensory systems, we decided to investigate the function and evolution of color vision (opsin genes) in these two suborders of bats. The middle/long wavelength (M/L) and short wavelength (S) opsin genes were sequenced from two frugivorous species of megabats, Haplonycteris fischeri and Pteropus dasymallus formosus, and one insectivorous species of microbat, Myotis velifer. Contrary to the situation in primates, where many nocturnal species have lost the functional S opsin gene, both crepuscular and strictly nocturnal species of bats that we examined have functional M/L and S opsin genes. Surprisingly, the S opsin in these bats may be sensitive to UV light, which is relatively more abundant at dawn and at dusk. The M/L opsin in these bats appears to be the L type, which is sensitive to red and may be helpful for identifying fruits among leaves or for other purposes. Most interestingly, H. fischeri has a recent duplication of the M/L opsin gene, representing to date the only known case of opsin gene duplication in non-primate mammals. Some of these observations are unexpected and may provide insights into the effect of nocturnal life on the evolution of opsin genes in mammals and the evolution of the life history traits of bats in general.

Amino Acid Sequence↗
PubMed1983

Clinical studies of color vision with Gunkel's chromagraph.

Color thresholds in a series of patients with local or systemic diseases were determined by a chromagraph method and subjected to computer analysis. When compared with normal persons, those with optic nerve disease (multiple sclerosis, optic neuritis, and optic atrophy) showed an overall weakness for all colors (enlarged neutral areas), with an additional specific defect in the orange-cyan (greenish blue) axis. Those with the two retinal diseases studied (macular degeneration and retinitis pigmentosa) also showed threshold elevation for all colors, but with a special defect in the yellow-blue axis. The general elevation was greater for patients with retinitis pigmentosa than for those with macular degeneration, regardless of the visual acuity. In patients undergoing treatment for systemic lupus erythematosus and rheumatoid arthritis, there was a mild elevation of the color threshold, especially for yellow.

Arthritis, Rheumatoid↗
PubMed1998

Mechanisms of central color vision.

In monkey cerebral cortex, color information is processed along the ventral visual pathway. This pathway starts in the primary visual cortex and ends in area TE of the inferior temporal cortex. Recent studies indicate that the transformation of cone signals occurs early in the pathway to form neurons selective to a narrow range of hues. In addition, it has become apparent that area TE plays a vital role in color discrimination.

Animals↗
PubMed1993

Photopigments and color vision in the nocturnal monkey, Aotus.

The owl monkey (Aotus trivirgatus) is the only nocturnal monkey. The photopigments of Aotus and the relationship between these photopigments and visual discrimination were examined through (1) an analysis of the flicker photometric electroretinogram (ERG), (2) psychophysical tests of visual sensitivity and color vision, and (3) a search for the presence of the photopigment gene necessary for the production of a short-wavelength sensitive (SWS) photopigment. Both electrophysiological and behavioral measurements indicate that in addition to a rod photopigment the retina of this primate contains only one other photopigment type--a cone pigment having a spectral peak ca 543 nm. Earlier results that suggested these monkeys can make crude color discriminations are interpreted as probably resulting from the joint exploitation of signals from rods and cones. Although Aotus has no functional SWS photopigment, hybridization analysis shows that Aotus has a pigment gene that is highly homologous to the human SWS photopigment gene.

Animals↗
PubMed1995

Color vision in Parkinson's disease: missing influence of amantadine sulphate.

In recent studies, disorders of chromatic and achromatic vision in parkinsonian patients have been demonstrated; these could be partially restored after application of L-Dopa. In this study, the effect of a 3-day infusion therapy with amantadine sulphate on color vision was evaluated in 19 parkinsonian patients by use of the Farnsworth-Munsell 100-Hue test. Under this treatment, the motor symptoms of parkinsonism improved significantly as assessed by the part "motor examination" of the Unified Parkinson's Disease Rating Scale (UPDRS). However, the total error scores of the Farnsworth-Munsell 100-Hue test before and after amantadine sulphate infusions were unchanged [before therapy, 94.53 (SD = 52.09); after therapy, 99.5 (SD = 58.81)]. From these results, it can be concluded that the pathophysiology of dopaminergic pathways in the visual system differs from that of the basal ganglia.

Aged↗
PubMed2003

Leaders of progressions in wild mixed-species troops of saddleback (Saguinus fuscicollis) and mustached tamarins (S. mystax), with emphasis on color vision and sex.

Leadership of travel progression is an important aspect of group living. It is widely believed that trichromacy evolved to facilitate the detection and selection of fruit in the dappled light of a forest. Further, it has been proposed that in New World primate species, which typically contain a range of color vision phenotypes, at least one female in a group will be trichromatic (i.e., having three types of visual pigment, in contrast to the two types of pigment found in dichromatic individuals) and will lead the group to fruiting trees. We examine progression leadership within two wild mixed-species troops of saddleback (Saguinus fuscicollis) and mustached (Saguinus mystax) tamarins over a complete year. As whole units, the mixed-species troops were most frequently led by a mustached tamarin. This is the first time that mixed-species group leadership and individual leadership have been quantified in these tamarin species. In terms of single-species intragroup leadership, neither the visual status (dichromatic or trichromatic) nor the sex of individuals had a consistent effect across species. Saddleback tamarin groups were led by males more frequently than females, while evidence suggests that mustached tamarins may be female-led. The notion that all groups contain at least one trichromatic female that leads the troop to feeding trees was not supported.

Animals↗