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PubMed1999

Performance of red-green color deficient subjects on the Holmes-Wright lantern (Type A) in photopic viewing.

BACKGROUND: The Holmes-Wright lantern (Type A) is an approved occupational color vision test for airline pilots in the European Economic Community and for specific occupations in the British Armed Forces. The colors shown are red, green and white signal lights. HYPOTHESIS: The Holmes-Wright lantern is a sensitive screening test for red-green color deficiency in photopic viewing and the pass/fail level is similar to that of the Farnsworth Lantern (Falant) if the same scoring method is applied. METHOD: There were 138 color deficient subjects identified with the Ishihara plates and diagnosed with the Nagel anomaloscope, completed a color vision test battery which included three runs of the nine color pairs of the Holmes-Wright lantern at high brightness in normal room illumination. RESULTS: Screening sensitivity on a single error was found to be 97% compared with the Ishihara plates. Using the Falant scoring method, 20 subjects passed. These were 1 deuteranope, 2 protanomalous trichromats and 17 deuteranomalous trichromats (22% of 88 anomalous trichromats). The mean error score was greater for protans than for deutans but the mean number of qualitative error categories was smaller. Green/white confusions were the most frequent errors. It was not possible to predict who would pass the lantern test from other test results but all subjects with a Nagel anomaloscope matching range > 15 scale units who failed the Farnsworth D15 test or were grading as moderate/severe with the American Optical Company (Hardy, Rand and Rittler) plates failed. CONCLUSIONS: The Holmes-Wright lantern is a sensitive screening test for red-green color deficiency. Although a similar percentage of anomalous trichromats fail the Holmes-Wright lantern as fail the Falant, if the same scoring method is used, the superior correlation between the Holmes-Wright result and other color vision tests designed to grade the severity of color deficiency suggests that the two lantern results are not equivalent.

Adult↗

PubMed2002

Effect of layering feldspathic porcelain on resulting veneer color with aluminum oxide core.

OBJECTIVE: To evaluate the resulting color of veneers affected by adding a layer of veneering porcelain on Procera aluminium oxide core. METHODS: Fifteen aluminium oxide disks were randomized into three groups. Each of five disks was veneered with porcelain of the Vita shade Al, A2 and B4 respectively. The color of the substrate covered with non-veneered disks and the veneered disks was measured separately and the color differences were calculated. RESULTS: Statistically significant differences (P < 0.01) in color coordinates of dark substrate were recorded between the substrate covered by an aluminium oxide disks and the addition of veneering porcelain to aluminium oxide disks. Mean coordinates color difference (DeltaE, DeltaL *, Deltaa *, Deltab *) after adding the three shades of veneering porcelain showed increase from Al (2.311) to A2 (4.313) to B4 (8.778) in DeltaE, decrease from Al (-1.530) to A2 (-3.369) and B4 (-3.358) in DeltaL *, and increase from Al (-1.440) to A2 (2.198) to B4 (7.955) in Deltab *. The direction of the color modification correlated with values obtained from the liberation. The resulting color was also affected by the color of the underlying structure. CONCLUSION: This study illustrates that color of aluminium oxide shell could be modified with feldspathic veneering porcelain, which may be used by practitioners to alter the esthetic outcome of porcelain veneers.

Aluminum Oxide↗

PubMedDate not supplied

Color vision in patients with the Hermansky-Pudlak syndrome.

PURPOSE: To study color vision in patients with oculocutaneous albinism (OCA) METHODS: We evaluated color vision in 42 patients with OCA using the HRR color plates. Sixty seven percent of the patients had the Hermansky-Pudlak syndrome (HPS), diagnosed genetically or clinically. The remaining patients had unknown mutations leading to OCA. RESULTS: 47.6 % of patients of OCA of all types included had a color vision defect. Of these, 55% were female and 45% were male patients. 50% of patients with the HPS (all types) had a color vision deficit. 42.9% of patients with OCA of unknown type had color weakness. 57.1% had normal color vision. CONCLUSIONS: Results suggest that many patients with OCA and the HPS have a mild red-green color perception deficiency that is not a sex linked trait. The prevalence of color vision deficits in our study population increased with decreasing visual acuity.

Adolescent↗

PubMed1988

A new perimetric color vision analyzer.

A new apparatus was developed for mapping the extrafoveal color vision, the perimetric color vision analyzer. A yellow test object with varying degrees of saturation is presented on a cathode ray tube color display in a random sequence at one of 10 points around the fixation spot. The background is a mosaic pattern consisting of gray spots of the same size and shape as the test object, with various luminances. Background patterns with or without a test object are presented alternately. The subject is instructed to press a key when he detects a yellow object in the background pattern. The luminance of the test object is in the same range as the background gray spots. Since the luminance of background spots is changed synchronously at random when the test object appears, the subject can detect the test object only by the difference in color saturation. The results show the color contrast sensitivity at every designated point in the central visual field. The clinical application of the perimetric color vision analyzer revealed extrafoveal color defects which could not be evaluated with conventional color vision tests. It also showed that in some chorioretinal and optic nerve disorders the topographic pattern of color contrast sensitivity disagrees with that of luminance contrast sensitivity measured with automated static perimetry.

Adult↗

PubMedDate not supplied

Translucency parameter of colorants for maxillofacial prostheses.

The masking power of various generic, dry mineral earth, and flocking colorants dispersed in medical-grade silicone elastomer was investigated. Reflectance measurements were made by diffuse reflectance spectrophotometry using black and white backings. These data were reduced to optical scattering and absorption coefficients through the use of the Kubelka-Munk reflectance theory. The color difference between a 0.13-cm-thick layer of the colored elastomer placed on an ideal black backing and this layer on an ideal white backing was calculated and established as a translucency parameter. Using analysis of variance and stepwise comparison testing, significant differences were found among the translucency parameters of the colorants. Since these colorants differ substantially in their ability to mask underlying colors and since the translucency of maxillofacial material is an important aspect of color measurement and natural appearance, differences in these colorants go beyond their obvious differences in color.

Absorption↗

PubMed1996

[Phylogenetic elements in Goethe's theory of colors].

Phylogenetic findings in the field of human color vision are compared with Goethe's theory of colors. Goethe's research into nature was often based on his view that whenever you find complex ("mannigfaltige') natural phenomena, there has always been a development from simple phenomena. In this connexion his interest focused on the identification of primordial phenomena ("Urphänomene') and not on the temporal aspects of development. This was also true for his studies of color. Based on erroneous interpretations of prismatic experiments, he put forward the theory that all colors developed from the two primordial colors yellow and blue, which were, according to Goethe, the two "first and simplest colors'. Although some of his assumptions were incorrect, his theory has many similarities with current phylogenetic findings, according to which our color vision is derived from an original perception of two colors, possibly yellow and blue. This similarity needs clarification on an interdisciplinary level as well as research to determine the degree to which Goethe's own physiological condition influenced his study of colors. The author suggests that a reappraisal of this, the largest section of Goethe's scientific work is now necessary.

Color↗

PubMedDate not supplied

Color space distortions in patients with type 2 diabetes mellitus.

Color vision impairment was examined in patients with type 2 diabetes mellitus (DM2) without retinopathy. We assessed the type and degree of distortions of individual color spaces. DM2 patients (n = 32), and age-matched controls (n = 20) were tested using the Farnsworth D-15 and the Lanthony D-15d tests. In addition, subsets of caps from both tests were employed in a triadic procedure (Bimler & Kirkland, 2004). Matrices of inter-cap subjective dissimilarities were estimated from each subject's "odd-one-out" choices, and processed using non-metric multidimensional scaling. Two-dimensional color spaces, individual and group (DM2 patients; controls), were reconstructed, with the axes interpreted as the R/G and B/Y perceptual opponent systems. Compared to controls, patient results were not significant for the D-15 and D-15d. In contrast, in the triadic procedure the residual distances were significantly different compared to controls: right eye, P = 0.021, and left eye, P = 0.022. Color space configurations for the DM2 patients were compressed along the B/Y and R/G dimensions. The present findings agree with earlier studies demonstrating diffuse losses in early stages of DM2. The proposed method of testing uses color spaces to represent discrimination and provides more differentiated quantitative diagnosis, which may be interpreted as the perceptual color system affected. In addition, it enables the detection of very mild color vision impairment that is not captured by the D-15d test. Along with fundoscopy, individual color spaces may serve for monitoring early functional changes and thereby to support a treatment strategy.

Adult↗

PubMed2000

A lantern color vision test for the rail industry.

BACKGROUND: Correct identification of wayside signal colors is critical for safe operation of railway equipment. However, evaluating color discrimination using just a screening test may not be occupationally relevant. METHODS: A lantern test (CNLAN) was designed to provide a functional assessment of color discrimination for the rail industry. It was validated against a simulated field trial. 81 individuals with normal color vision and 74 individuals with congenital red-green defects participated. Color vision was classified using the Nagel Anomaloscope. RESULTS: Using a criterion based on the worst-normal performance, 97% of the individuals with a color vision defect failed both the CNLAN and simulation trial. This value is slightly lower than the 100% who failed both the Ishihara test and simulation. However, the Ishihara test also failed 3.7% of the color-normals who passed both the simulation and lantern, whereas by definition none of the color-normals failed the lantern. CONCLUSIONS: This lantern test provides a reasonable functional assessment of one's ability to identify rail signal colors; especially when a strict failing criterion is applied to screening tests.

Accidents, Occupational↗

PubMed1995

The organization of the turtle inner retina. II. Analysis of color-coded and directionally selective cells.

Color coding and directional selectivity (DS) of retinal neurons were studied in the Pseudemys turtle by using similar intracellular recording and staining techniques as in the preceding paper (J. Ammermüller and H. Kolb, 1995, J. Comp. Neuronal. 358:1-34). Color-coded responses were elicited by red (621 or 694 nm), green (525 or 514 nm), and blue (455 nm) light flashes. In addition to red/green and yellow/blue types of chromaticity horizontal cells, in our sample of 305 identified cells we found that 17% of bipolar cells, 6.5% of amacrine cells, and 18% of ganglion cells exhibit color-coded responses. DS responses were found in 37% of the tested ganglion cells and 41% of the tested amacrine cells. Two morphologically identified bipolar cell types, B10 and B11, were red-ON/blue-OFF and red-OFF/green, blue-ON, respectively. Of five identified amacrine cell types, three were red-OFF/blue-ON center (A1, A3, A23b), one was red-OFF/green-ON center (A32), and one (A33) was double color-opponent of red-ON/blue-OFF center:red-OFF/blue-ON surround. Five ganglion cell types had variously color-coded centers (G14 and G24) or surrounds (G3 and G18), including one type, G6, that was double color-opponent (red-OFF/green-ON center:red-ON/green-OFF surround). Responses to colors were found primarily in sustained responses of bipolar and ganglion cells. However, in amacrine cells, transient components of the response also showed color dependence. Red-OFF-center responses were found in ganglion cells that were in a position to make connections at the strata 2/3 border with the red-OFF bipolar cell (B11); red-ON-center responses occurred in ganglion cells with branches in stratum 4 of the IPL where the red-ON-center bipolar (B10) ended. Blue-ON-center signals appeared to be processed mainly in strata 1-2/3, and blue-OFF-center signals in strata 3-5 of the IPL, with contributions of amacrine cells and bipolar cells. Labeled DS amacrine cells could be identified as A9, A20, and A22, and ganglion cells as G19, G20, and G24. The latter type (G24) showed DS and color coding. All response types (ON-center, OFF-center, ON-OFF) were encountered. DS amacrine cells were monostratified near the middle of the IPL, whereas DS ganglion cells were mono-, bi-, and multistratified, although all DS ganglion cells had one feature in common: they had dendrites in stratum 1 of the IPL.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2003

The effect of 30% hydrogen peroxide on the color of compomers.

The interaction between bleaching agents and recently introduced compomers has several issues that need to be explored, including morphology and mechanical properties. To investigate the effect of 30% hydrogen peroxide, a bleaching agent, on the color of compomers, three compomers (Compoglass F, Elan, and F2000) were polymerized, bleached up to 120 h, and then measured to determine the reflectance of the specimen during the bleaching process. Color differences were evaluated from the reflectance and color values that were represented by CIE L*a*b* values. Compomers stored in distilled water were used as a source of reference. Teeth were also used for comparison. Color differences for both the tested teeth and compomers and different periods of bleaching and soaking in distilled water showed statistically significant difference (p < 0.0001). Among the tested compomers, Compoglass F demonstrated the highest color difference. In addition, the color differences were maximal during the first 24 h. After 24 h, the color difference increased nearly linearly. Compomers stored in both a bleaching agent and distilled water did not exhibit much color difference between them. However, the color difference between teeth and compomers was considerable.

Animals↗

PubMed2001

Conceptualization of perceptual attributes: a special case for color?

Young children experience difficulties establishing conceptual representations of color compared with everyday objects. We argue that comparing the development of color cognition to that of familiar objects is inappropriate since color is a perceptual attribute that can be abstracted from an object and by itself lacks functional significance. Instead, we compared the recognition, perceptual saliency, and naming of color to that of three other perceptual object attributes (motion, form, and size) in 47 children aged 2 to 5 years as a function of language age. Results revealed that, although color was perceptually salient relative to the other visual attributes, no selective impairment to color cognition (recognition and naming) was found relative to the three other visual attributes tested. Thus, when the appropriate comparisons are made, we find no special delay in the development of color conceptualization. Furthermore, the striking disparity between perceptual saliency and cognition of color in our youngest age groups suggests that perceptual saliency has little influence on the conceptual development of color.

Child↗

PubMed1994

Comparing color-word and picture-word Stroop-like effects: a test of the Glaser and Glaser (1989) model.

Glaser and Glaser (1989) assume that the processing of colors and pictures is highly similar in that, compared to words, both kinds of stimulis have privileged access to semantic information. This assumption was tested in the present research. In Experiment 1, the season corresponding to the color or to the word of color-word Stroop stimuli had to be named (e.g., green for spring). In Experiment 2, subjects had to name the season corresponding to the picture or the word of a picture-word stimulus (e.g., flower for spring). According to Glaser and Glaser (1989), privileged semantic processing of colors and pictures should be evidenced by a larger interfering power of color and picture distractors than of word distractors. However, the asymmetric pattern of interference was observed only with picture-word stimuli (Experiment 2), but not with color-word stimuli (Experiment 1), suggesting that, unlike pictures, colors do not have privileged access to semantic information. It was also found that word distractors interfered with the semantic processing of pictures, a result that is incompatible with the dominance rule postulated by Glaser and Glaser (1989). From these results, an adapted version of the Glaser and Glaser model is proposed: colors are assumed to have privileged access to a separate color-processing system and the pattern of interference depends upon the relative activation strength of the response alternatives activated by the target and the distractor.

Adult↗

PubMed1987

Value and limitations of color Doppler flow mapping in the detection and semiquantification of valvular regurgitation.

We compared color Doppler flow mapping data to angiographic data in 294 patients with suspected valvular regurgitation. Thirty-one patients had rheumatic mitral regurgitation and 37 had mitral regurgitation due to mitral valve prolapse by angiography. Ten patients had no angiographic regurgitation (4 rheumatic, 6 prolapse). The remaining patients included 86 with suspected aortic regurgitation and 130 with suspected tricuspid regurgitation. Angiographically 74 had aortic regurgitation and 111 tricuspid regurgitation. The maximum size of regurgitant jets was evaluated in each patient by color flow mapping. The width of the jets was also taken into consideration. In 29 of the 31 with rheumatic regurgitation and 67 of the 74 with aortic regurgitation by angiography, abnormal regurgitant signals were detected by color flow mapping. In both rheumatic mitral regurgitation and aortic regurgitation, color Doppler estimation of the jets correlated well with angiographic grading. The regurgitant jets in these regurgitation were not eccentric. In the 37 with mitral regurgitation in mitral valve prolapse by left ventriculography, abnormal jets were detected in 35 by color flow mapping. However, the regurgitant jets were eccentric and color Doppler estimation of the jets correlated poorly with angiographic grading. In patients with tricuspid regurgitation, color Doppler grading of regurgitation correlated poorly with right ventriculographic grading. A color Doppler underestimation was observed in 48%. In conclusion, color Doppler flow mapping is useful in the noninvasive detection and semiquantification of rheumatic mitral regurgitation and aortic regurgitation having non-eccentric jets, although this technique often underestimates the severity of regurgitation in mitral valve prolapse.

Aortic Valve Insufficiency↗

PubMed1999

Characterization of color CRT display systems for monochrome applications.

Soft-copy presentation of medical images is becoming more and more important as medical imaging is strongly moving toward digital technology, and health care facilities are converting to filmless hospital and radiological information management. Although most medical images are monochrome, frequently they are displayed on color CRTs, particularly if general-purpose workstations or PCs are used for medical viewing. In the present report, general measurement and modeling procedures for the characterization of color CRT monitors for monochrome presentation are introduced. The contributions from the three color channels (red, green, and blue) are weighted according to the spectral sensitivity of the human eye for photopic viewing. The luminance behavior and the resolution capabilities of color CRT monitors are analyzed with the help of photometer and charge-coupled device (CCD) camera measurements. For the evaluation of spatial resolution, a two-dimensional Fourier analysis of special test images containing white noise (broadband response) is employed. A stage model for a color CRT monitor is developed to discuss the effects of scanning and dot sampling. Furthermore, display intrinsic veiling glare and reflectivity of typical color CRT monitors are measured and compared with those of monochrome CRT monitors. The developed methods and models allow one to describe the image quality aspects of color monitors if they are applied for medical monochrome image presentation. Particularly, because of the reduced luminance and dynamic range of color monitors, the calibration and control of their luminance curves is a very important task. For present color CRT monitors, 1,280 x 1,024 turns out to be an intrinsic limit for the displayable matrix of medical images.

Color↗

PubMed1996

[The value of color-coded duplex ultrasound as standard assessment in erectile dysfunction].

Erectile dysfunction has taken on increasing importance in urologic practice. Still open is the question of which tests are mandatory for adequate clinical assessment of erectile dysfunction. One accepted standard modality is the intracavernous pharmacotest with vasoactive agents. In contrast, color duplex sonography is not considered mandatory although it reveals detailed information about penile vessels and functional implications. The question remains whether the information gained by color duplex sonography is relevant for therapy, making it an indispensable standard procedure. Patients with erectile dysfunction were evaluated, without preselection, by extensive history, clinical evaluation, laboratory tests, tumescence and rigidity measurements, intracavernous administration of vasoactive drugs and color duplex sonography. Seventy-nine patients were available for final analysis. Color duplex sonography revealed 39 normal tests, 16 arterial impairments. 19 venous leakages and 5 arteriovenous fistulae. Intracavernous vasoactive agents (pharmacotest) revealed 44 reactions sufficient for intercourse and 35 insufficient responses. In 89% of patients, the diagnoses on color duplex sonography and intracavernous pharmaco-testing were similar. The accuracy of the two methods in diagnosing erectile dysfunction was not statistically different (McNemar's test). In contrast to intracavernous pharmaco-testing, color duplex sonography permitted further etiologic subdivision into arterial disease, venous leakage, arteriovenous fistula and normal result. This was made possible by measuring significantly (P < 0.01) different arterial peak flow velocities, end-diastolic velocities and calculated resistance index. These data did not imply direct clinical consequences. Color duplex sonography and intracavernous pharmacotesting reveal comparable results concerning the diagnosis of an erectile dysfunction. In contrast to pharmacotesting, color duplex sonography reveals details of the nature of the erectile dysfunction. Because this information has no profound implications for the choice of therapeutic procedure, color duplex sonography can not be recommended as a standard procedure in the evaluation of erectile dysfunction.

Adolescent↗

PubMedDate not supplied

Color Doppler findings of gastrointestinal varices.

BACKGROUND: Compared with esophageal varices, gastrointestinal varices are relatively rare, but they are clinically important because they tend to bleed massively. Color Doppler sonography is now widely used to diagnose the collaterals, but few color Doppler findings of gastric or intestinal varices have been reported. The aim of this study was to investigate the sonographic and color Doppler findings of gastrointestinal varices and to determine the role of color Doppler sonography in the diagnosis of these varices. METHODS: We studied 30 patients who were diagnosed by endoscopy as having gastrointestinal varices (24 gastric, four duodenal, two intestinal) with color Doppler sonography and compared the results with the clinical data. The causes of gastric varices included liver cirrhosis (16/24, 66.7%), idiopathic portal hypertension (3/24, 12. 5%), chronic pancreatitis with splenic vein thrombosis (2/24, 8.3%), congenital biliary atresia (1/24, 4.2%), congenital hepatic fibrosis (1/24, 4.2%), and unknown (1/24, 4.2%). The causes of duodenal varices included idiopathic portal hypertension with portal thrombosis (3/4, 75%) and liver cirrhosis (1/4, 25%). RESULTS: The gastric wall at the fundus was thickened in 17 of 24 cases (70.8%) with gastric varices, and the duodenal wall was thickened in four of four cases (100%) with duodenal varices. Sonography revealed thrombosis in the splenic vein in two of two cases with gastric varices secondary to chronic pancreatitis and in the confluence of the superior mesenteric vein and the splenic vein in three of four cases with duodenal varices. Color Doppler sonography demonstrated multiple, slow constant blood flows in the thickened wall in 15 of 24 cases (62.5%) with gastric varices and in four of four cases (100%) with duodenal varices. It demonstrated accumulated slow constant blood flows in the cecum in the case with cecal varices. Color Doppler showed also the communication between the varices and the neighboring vascular system (superior mesenteric vein and inferior vena cava) in the case with cecal varices, but it did not directly reveal such a communication in the other 29 cases (96.7%). Color Doppler showed a hepatofugal flow in the left gastric vein in all the hemorrhagic gastric varicose patients with esophageal varices, but it showed a hepatopetal flow in the left gastric vein in the isolated nonhemorrhagic gastric varicose patients. CONCLUSION: Color Doppler sonography was very useful for the diagnosis of gastric and duodenal varices and for visualizing fine venous flows in the thickened gastric or duodenal wall. When it shows portal thrombosis in the confluence of the splenic vein and the superior mesenteric vein, duodenal varices should be suspected. The flow direction of the left gastric vein helps to differentiate hemorrhagic gastric varices from nonhemorrhagic ones.

Adolescent↗

PubMed2004

Clinical evaluation of color Doppler imaging for the differential diagnosis of thyroid follicular lesions.

Ultrasonography (US) of the thyroid gland has recently proved to be a useful clinical diagnostic method, and the newly developed high-resolution US with a color Doppler flow mapping function can reveal fine details of the thyroid gland and the hemodynamic features of a thyroid neoplasm. US can yield a diagnostic accuracy of more than 90% for thyroid carcinoma, especially papillary carcinoma. However, neither conventional B-mode US imaging nor aspiration biopsy cytology has delivered satisfactory results for follicular carcinoma. The aim of this study was to evaluate the clinical usefulness of color Doppler imaging for the differential diagnosis of thyroid follicular lesions. A color Doppler scan was performed in 310 patients with a solitary cold nodule, and a combination of B-mode US and color Doppler findings, including tumor vascularity and results of a fast Fourier transform (FFT) analysis were used to create the following diagnostic grading system for differential diagnosis of follicular lesions: grade 1, benign follicular lesion [no color flow mapping (CFM) inside the nodule]; grade 2, benign peripheral type [CFM only in peripheral area, pulsatility index (PI) < 1.0]; grade 3, suspected follicular carcinoma (penetrating CFM, vascularity moderate); grade 4, follicular carcinoma (high-velocity penetrating CFM, PI = 1.0). All patients were subjected to surgical resection, and histologic examination was used to confirm the diagnosis. The grades of the 177 adenomatous nodules were as follows: grade 1, 46.9%; grade 2, 48.0%; grade 3, 5.1%; grade 4, 0%. The corresponding percentages for the 89 follicular adenomas were 16.9%, 49.4%, 30.3%, and 3.4%; and for the 44 follicular carcinomas they were 0%, 13.6%, 45.5%, and 40.9%. On the assumption that grade 1 and 2 lesions are benign and grade 3 and 4 lesions are malignant, 38 of the 44 follicular carcinomas and 227 of the 266 benign tumors had been accurately diagnosed, yielding a sensitivity of 88.9%, a specificity of 74.2%, and an accuracy of 81.0% for the grading system. Color Doppler imaging of 310 follicular tumors has revealed that high-velocity pulsatile blood flow penetrating the tumor is a characteristic finding of follicular carcinoma and is a new diagnostic criterion for performing color Doppler imaging. The differential diagnostic grading scores for color Doppler examinations and the results of FFT analysis demonstrate that US with the color Doppler function can play an important role in the differential diagnosis of thyroid tumors.

Adenoma↗

PubMed2006

Investigation of the role of the agouti signaling protein gene (ASIP) in coat color evolution in primates.

We investigated variation in the gene encoding the agouti signaling protein (ASIP) in relation to coat color evolution in primates. We found little evidence that mutations in the coding region of ASIP have been involved in color changes among closely related primate species. Among many closely related species with differing coat color, the coding region of ASIP was identical. In two cases (Sulawesi macaque and black lion tamarin) where species with almost completely black coat color had derived point mutations in exon 4 of the ASIP coding sequence, the same mutations did not alter coloration in other mammals and so probably do not affect ASIP function. Evolutionary reconstructions of two key phenotypes that are typically related to ASIP function--transverse phaeomelanin bands on hairs and pale ventral coloration--showed that these usually evolved concurrently, suggesting that loci acting downstream of ASIP may be involved. Analysis of dN/dS ratios revealed a likely change in functional constraint on ASIP following loss of agouti-banded hairs + pale ventral coloration, particularly in catarrhine primates (humans, apes, and Old World monkeys). Together with previous results on a lack of association of coat color with MC1R variation, these results suggest that other loci probably have an important role in primate coat color evolution.

Agouti Signaling Protein↗