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PubMed2001

Assessment of aspiration in patients with tracheostomies: comparison of the bedside colored dye assessment with videofluoroscopic examination.

BACKGROUND: Aspiration is a serious clinical concern in patients with long-term artificial airways. The purpose of this study was to determine the reliability of a bedside colored dye assessment of aspiration in tracheostomized patients and to determine its comparability to a more sophisticated videofluoroscopic study. METHODS: This was a prospective, blinded comparison study conducted in a large, urban, university teaching hospital. We studied 20 consecutive patients who underwent tracheostomy for bronchial hygiene needs and who were referred for videofluorographic evaluation for suspected oropharyngeal dysphagia and possible aspiration. Excluded were patients unable to follow verbal commands and those requiring mechanical ventilatory support. All patients were brought to the videofluorography suite for colored dye assessment for aspiration and videofluorographic assessment of oropharyngeal swallow. A nurse, blinded to the results of videofluorographic swallow study, performed colored dye assessments for aspiration. Speech-language pathologists, blinded to the results of the colored dye assessments, interpreted simultaneous (preliminary) and subsequent complete (final) videofluorographic evaluations of swallow. RESULTS: The colored dye aspiration assessments and the videofluoroscopic studies were compared for the frequency of aspiration detection. Sensitivity and specificity were determined using standard methods. Seven patients showed no aspiration on either the colored dye test or videofluoroscopic examination. Eight patients were judged to aspirate by videofluorography but not by the colored dye test. Five patients were judged to aspirate by both the colored dye test and videofluorography. The data indicate that the colored dye test for aspiration carries a low sensitivity of 38% (95% confidence interval = +/- 7%), but a high specificity of 100%. The videofluoroscopic study detected a significantly greater frequency of aspiration than did the colored dye test (p < 0.01). CONCLUSIONS: The colored dye test for aspiration can provide useful information when positive, but because there is a significant false negative rate, decisions made on the basis of a negative test must be made with caution.

Adult↗

PubMed2005

[An automatic color correction algorithm for digital human body sections].

OBJECTIVE: To find a new approach to improve the uniformity of color parameters for images data of the serial sections of the human body. METHOD: An auto-color correction algorithm in the RGB color space based on a standard CMYK color chart was proposed. The gray part of the color chart was auto-segmented from every original image, and fifteen gray values were attained. The transformation function between the measured gray value and the standard gray value of the color chart and the lookup table were obtained. In RGB color space, the colors of images were corrected according to the lookup table. RESULT: The color of original Chinese Digital Human Girl No. 1 (CDH-G1) database was corrected by using the algorithm with Matlab 6.5, and it took 13.475 s to deal with one picture on a personal computer. CONCLUSION: Using the algorithm, the color of the original database is corrected automatically and quickly. The uniformity of color parameters for corrected dataset is improved.

Algorithms↗

PubMed2006

Visually guided movements to color targets.

The pathways controlling motor behavior are believed to exhibit little selectivity for color, but there is growing evidence suggesting that color signals can be used to guide actions. We investigated this by having observers make a saccade or a rapid pointing movement to a small, peripherally flashed (100 ms) Gaussian target (SD=0.5 degrees) defined exclusively by luminance (maximum contrast) or color (from cardinal DKL red-green or blue-yellow axes, at maximum saturation). We found no difference in saccadic or pointing accuracy for luminance or color targets. The same was true using shutter goggles during pointing (to minimize the use of external cues), and when the luminance contrast of color targets was varied by up to +/-10%. In terms of response times, both eye and hand latencies increased with target eccentricity for R-G targets only, in a manner consistent with the sensitivity of this channel across eccentricity. We found little difference in response latencies between luminance and color targets once matched in terms of cone contrast. While RTs were longer when coupled with a goal directed pointing movement (versus a simple reaction without pointing), the difference was the same for color or luminance targets, suggesting that the spatial coding for the movements was also the same. In a final experiment we compared the accuracy of pointing to color-naming performance in a 4AFC procedure. The psychometric functions relating pointing accuracy (% correct quadrant) to color-naming (% correct color-name) were identical. Taken together, the results show that human observers can efficiently use pure chromatic signals to guide actions.

Analysis of Variance↗

PubMed2005

The color of human gingiva and mucosa: visual measurement and description of distribution.

No soft tissue shade guide is available for matching the color of denture resins to human intraoral soft tissues. To determine the color of both the gingiva and the alveolar mucosa, intraoral soft tissue colors of 150 men and women were assessed under standardized lighting conditions. Colors of the papilla, attached gingiva, and alveolar mucosa in the central incisor region of the maxilla and mandible were examined using Munsell color tabs and their corresponding notations (value, hue, chroma). Statistical evaluation was performed by using frequency tables and multiple regression (level of significance p=0.05). Color ratings for the maxillary interincisal papilla lay in the yellow hue spectrum. A high incidence of ratings was found between 7/6 2.5R and 7/4 5R (Munsell color notations). Two further peaks were identified for the colors 3/6 2.5 R and 8/4 10R. Five peaks with the highest frequency of ratings were present with regard to the color of the mucosa in the maxillary incisal region: 6/6 2.5R, 7/6 2.5R, 6/8 5R, 5/8 7.5RP, and 5/6 10RP. In the mandible, a similar pattern was found. Using the results from visual matching tests, five color frequency peaks were identified. They could be used to construct an intraoral soft tissue shade guide.

Adult↗

PubMed2006

Effect of esthetic core shades on the final color of IPS Empress all-ceramic crowns.

STATEMENT OF PROBLEM: Clinically relevant assessment of all-ceramic crowns supported by esthetic composite resin foundations has not been evaluated with regard to color reproducibility. PURPOSE: This in vitro study quantitatively evaluated the influence of different shades of composite resin foundations and resin cement on the final color of a leucite-reinforced all-ceramic material. MATERIAL AND METHODS: A total of 128 disks were fabricated; 64 (20 x 1 mm) were made of all-ceramic material (IPS Empress) and 64 (20 x 4 mm) of 4 different shades composite resin (Tetric Ceram). The ceramic and composite resin disks were luted using 2 shades (A3 and Transparent) of resin cement (Variolink II). Color was measured using a colorimeter configured with a diffuse illumination/0-degree viewing geometry, and Commission Internationale de l'Eclairage (CIE) L( *)a( *)b( *) values were directly calculated. Descriptive statistical analysis was performed, and color differences (DeltaE) for the average L( *), a( *) and b( *) color parameters were calculated. Repeated measures analysis of variance (ANOVA) was used to compare mean values and SDs between the different color combinations (alpha=.05). RESULTS: The CIE L( *)a( *)b( *) color coordinate values showed no significant differences for variation in color parameters due to the effect of the different composite resin shades (P=.24) or cement shades (P=.12). The mean color difference (DeltaE) value between the groups was 0.8. CONCLUSION: Within the limitations of this study, the use of different shades for composite resin cores and resin cements presented no statistically significant effect on the final color of IPS Empress all-ceramic material.

Acrylic Resins↗

PubMed1999

Color stability of heat-polymerized and autopolymerized soft denture liners.

STATEMENT OF PROBLEM: The physical and mechanical properties of soft denture liners are influenced by a number of factors. Aging is one factor that has an effect on the characteristics of polymers. The resistance of denture liners to aging can potentially influence the color stability of these liners. PURPOSE: This study attempted to determine the color stability of soft liners by subjecting them to an in vitro accelerated aging test. MATERIAL AND METHODS: Two autopolymerizing and 3 heat polymerizing commercially available soft denture lining materials were tested. Seven sample disks were made of each material according to manufacturers' instructions. Color measurements were recorded before and after the accelerated aging process. Color changes (DeltaE) were calculated by measuring tristimulus values at several wavelengths in the visual spectrum with the use of Commission International de l'Eclairge Lab (CIE-LAB) uniform color scale. RESULTS: Kruskall-Wallis variance analysis and Mann-Whitney U-Wilcoxon rank sum W tests were performed for statistical comparison of the DeltaE values. Ufigel P and Simpa liner materials showed significantly greater color changes than the other tested materials. There were no significant differences in color change among Ufigel L-Molloplast B, Ufigel L-Flexor, and Molloplast B-Flexor liner materials. However, a significant difference in color change was found between Ufigel P and Simpa liners. CONCLUSION: Heat-polymerized soft liners were more color stable than autopolymerized soft liners. No significant differences were found among heat polymerized materials; however, significant differences in color change were found between the 2 autopolymerized liners.

Analysis of Variance↗

PubMed2000

Sensory and cognitive contributions of color to the recognition of natural scenes.

Although color plays a prominent part in our subjective experience of the visual world, the evolutionary advantage of color vision is still unclear [1] [2], with most current answers pointing towards specialized uses, for example to detect ripe fruit amongst foliage [3] [4] [5] [6]. We investigated whether color has a more general role in visual recognition by looking at the contribution of color to the encoding and retrieval processes involved in pattern recognition [7] [8] [9]. Recognition accuracy was higher for color images of natural scenes than for luminance-matched black and white images, and color information contributed to both components of the recognition process. Initially, color leads to an image-coding advantage at the very early stages of sensory processing, most probably by easing the image-segmentation task. Later, color leads to an advantage in retrieval, presumably as the result of an enhanced image representation in memory due to the additional attribute. Our results ascribe color vision a general role in the processing of visual form, starting at the very earliest stages of analysis: color helps us to recognize things faster and to remember them better.

Cognition↗

PubMed2000

Double-layer porcelain veneers: effect of layering on resulting veneer color.

STATEMENT OF PROBLEM: Densely sintered aluminum oxide veneered with feldspathic porcelain seems to be a promising technology for the fabrication of porcelain laminate veneers, which provide both strength and esthetics. To effectively use this approach for porcelain veneers, practitioners should know how the resulting color is affected by adding a layer of veneering porcelain onto the aluminum oxide. PURPOSE: This study compared changes in CIE L*a*b* color coordinates of simulated stained teeth when covered with the aluminum oxide core disks alone and after the disks had been veneered with 3 different shades of porcelain. MATERIAL AND METHODS: Fifteen aluminum oxide disks were divided into 3 groups. Each of 5 disks was veneered with porcelain of the Vita shades A1, A2, and B4, respectively. The colors of the substrate covered with the nonveneered disks and the veneered disks were measured separately, and the color differences were calculated. Measurements of the disks on a white background were also performed and used as controls. The extracted data were compared with Vita shade values available from the literature. RESULTS: Statistically significant differences in color coordinates of dark substrates were recorded between the substrate covered by an aluminum oxide disk and the addition of veneering porcelain to the aluminum oxide disks. Veneering the aluminum oxide disks with A1, A2, and B4 porcelain produced significant differences in the resulting color when placed on a dark substrate. The direction of the color modifications correlated with values obtained from the literature. The resulting color was also affected by the color of the underlying structures. CONCLUSION: Although aluminum oxide alone does have a degree of masking capability, the resulting color of porcelain veneers with the use of this material can successfully be modified with the veneering porcelain.

Aluminum Oxide↗

PubMed2002

Variation in color between intended matched shade and fabricated shade of dental porcelain.

STATEMENT OF PROBLEM: The total quantifiable color difference between shade matching and shade duplication has not been investigated formally. PURPOSE: The purpose of this in vitro study was to evaluate and compare the color difference of the total color replication process and the direction of the individual color parameters for 3 dental porcelain shade-matching systems. MATERIAL AND METHODS: The shade of 11 porcelain master disks was determined visually and instrumentally using 3 porcelain shade-matching systems: (1) Vita Lumin/Vita VMK 68, (2) Vitapan 3D-Master/Vita Omega 900, and (3) Shofu ShadeEye-EX/Vintage Halo. Corresponding porcelain disks made of 4.5 mm opaque and 1 mm dentin porcelain were fabricated with each of the porcelain systems. The colors of the master disks and fabricated disks (CIE L* a* b* coordinates) were measured with a spectroradiometer with a 45 degrees /0 degrees configuration. Repeated-measures analysis of variance was used to evaluate within-group differences among the porcelain systems for the total color difference (Delta E) and direction of the color parameters (Delta L, Delta a, and Delta b). The Ryan-Einot-Gabriel-Welsch multiple range test was used for post-hoc analysis (alpha=.05). RESULTS: The largest mean Delta E was recorded for the Vitapan 3D-Master system, which was significantly different from the other systems (P=.0024). A significant difference was found between the interaction of the different systems and the direction of color (P=.0024). The amount of change within each color parameter was dependent on the porcelain system, as well as the amount of change among the color parameters. CONCLUSION: Within the limitations of this study, the results suggest that reliable delivery of a properly matched restoration to existing porcelain restorations cannot be ensured regardless of the shade assessment method used (visual or computer-generated).

Algorithms↗

PubMed2006

Discrete color filling beyond luminance gaps along perceptual surfaces.

Perceived color at a point in space is not determined simply by the color directly stimulating the corresponding retinal position. Surface color is informed by flanking edge signals, which also serve to inhibit the intrusion of signals from neighboring surfaces. Spatially continuous local interactions among color and luminance signals have been implicated in a propagation process often referred to as filling-in. Here, we report a phenomenon of discrete color filling whereby color jumps over luminance gaps filling into disconnected regions of the stimulus. This color filling is found to be blocked at boundaries defined by texture. The color filling is also highly specific to the elements belonging to a common perceptual surface, even when multiple surfaces are transparently overlaid. Our results indicate that color filling can be governed by a host of visual cues outside the realm of first-order color and brightness, via their impact on perceptual surface segmentation and segregation.

Color Perception↗

PubMed1998

Color-luminance interaction: data produced by oblique cross masking.

Threshold-elevation (TE-) versus-mask-spatial-frequency (SF) curves and TE-versus-mask-contrast curves, produced by the oblique-masking technique, were reported for uncrossed stimuli (color-test-on-color-mask and luminance-test-on-luminance-mask) [Invest. Ophthalmol. Visual Sci. Suppl. 34, 751 (1993) and Vision. Res. 23, 873 (1983)]. The technique minimizes the artifacts that are due to spatial phase effects, spatial beats, spatial probability summation, and local cues. My goal was to measure these curves for crossed stimuli (color-test-on-luminance-mask and luminance-test-on-color-mask) by this oblique-masking technique and to compare the curves with those reported in previous studies. For this purpose threshold contrasts were measured by a yes-no procedure with randomized double staircases. Test targets were vertical spatially localized (D6) patterns, and masks were oblique sinusoidal patterns; both the test and the mask were presented simultaneously, for 2 s (Gaussian window), on a color monitor interfaced with an ATVista system and a Powell achromatizing lens. The test SF's were 0.125, 0.5, 2, 4, and 8 cycles per degree (cpd); mask SF's were 0.031-16 cpd; and mask contrasts were 6.25%-50%. Furthermore, the Red-Green channel was defined by the minimum flicker and the hue cancellation techniques. Results show mostly masking effect (TE > 1) at contrasts above threshold; sometimes, separability (TE = 1) and above-threshold facilitation (TE < 1) effects were also observed, depending on the test SF, the mask SF, the mask contrast, and the subject. In general, the magnitudes of TE's are smaller and the TE-versus-mask-SF curves are slightly narrower for the oblique-cross-masking conditions than those for the respective oblique uncross masking. In addition, the TE-versus-mask-contrast curves for the crossed conditions are mostly shallower than those for the respective uncrossed conditions. Furthermore, mostly the color-luminance asymmetry (color masks luminance more than luminance masks color) is found, in mild form, for SF's > or = 0.5 cpd. For the lower SF of 0.125 cpd, there is either a lack of asymmetry or a very mild asymmetry of the opposite kind (luminance masks color slightly more than color masks luminance) seems to prevail. In general, the oblique-masking data shows mild asymmetry and reduced facilitation; both are consistent with reduced local cues, similar to those shown by randomized phase data, thus making the data suitable for SF analysis; moreover, at high contrast, the masking data are consistent with those reported in previous studies.

Adult↗

PubMed2001

Color constancy at a pixel.

In computational terms we can solve the color constancy problem if device red, green, and blue sensor responses, or RGB's, for surfaces seen under an unknown illuminant can be mapped to corresponding RGB's under a known reference light. In recent years almost all authors have argued that this three-dimensional problem is too hard. It is argued that because a bright light striking a dark surface results in the same physical spectra as those of a dim light incident on a light surface, the magnitude of RGB's cannot be recovered. Consequently, modern color constancy algorithms attempt only to recover image chromaticities under the reference light: They solve a two-dimensional problem. While significant progress has been made toward achieving chromaticity constancy, recent work has shown that the most advanced algorithms are unable to render chromaticity stable enough so that it can be used as a cue for object recognition [B. V. Funt, K. Bernard, and L. Martin, in Proceedings of the Fifth European Conference on Computer Vision (European Vision Society, Springer-Verlag, Berlin, 1998), Vol. II, p. 445.] We take this reductionist approach a little further and look at the one-dimensional color constancy problem. We ask, Is there a single color coordinate, a function of image chromaticities, for which the color constancy problem can be solved? Our answer is an emphatic yes. We show that there exists a single invariant color coordinate, a function of R, G, and B, that depends only on surface reflectance. Two corollaries follow. First, given an RGB image of a scene viewed under any illuminant, we can trivially synthesize the same gray-scale image (we simply code the invariant coordinate as a gray scale). Second, this result implies that we can solve the one-dimensional color constancy problem at a pixel (in scenes with no color diversity whatsoever). We present experiments that show that invariant gray-scale histograms are a stable feature for object recognition. Indexing on invariant distributions supports almost perfect recognition for a dataset of 11 objects viewed under five colored lights. In contrast, object recognition based on chromaticity histograms (post-color constancy preprocessing) delivers much poorer recognition.

Artificial Intelligence↗

PubMed2004

Thresholds of color attribute differences in detecting camouflaged textures.

We examined the threshold at which a camouflaged color texture pattern (target) embedded in a surrounding colored texture pattern (background) was discriminated by making the difference between their color distributions serve as a cue. The texture consisted of 900 colored disks. The color applied to the disk was chosen from a normal distribution with the mean and the standard deviation set beforehand. The mean of the background's distribution was a standard achromatic color set at L*=40, u*=0, and v*=0 of CIELUV. In experiment 1, the mean of the target's color distribution was shifted from the background's one. The threshold for the mean of the target's color distribution depended on the standard deviation and increased as the standard deviation became bigger. In experiment 2, the standard deviation of the target's color distribution was shifted. There was the slight dependence of threshold of the standard deviation of the target's distribution on that of the background's distribution. In experiment 3, both of the mean and the standard deviation of the target's color distribution were shifted at the same time. The threshold was not determined by each of the mean and the standard deviation independently. There seemed to be some compensating contribution between them to each other. The threshold could be characterized by Doyle metric or modified Doyle metric.

Color↗

PubMed1997

Long wavelength pass filters designed for the management of color vision deficiencies.

This study reports on the effectiveness of long wavelength pass filters dispensed as tinted spectacles as an aid for individuals with congenital red-green color vision deficiencies. The effectiveness of the filters was evaluated by the performance on a series of clinical color vision tests and a questionnaire after the subjects had tried the lenses for 1 week. The lenses improved performance on color vision tests that required discrimination between large color differences, particularly between red and green hues. However, performance was degraded on tests which required fine color discrimination or used colors that were located parallel to the tritan confusion axis. The improved performance on certain tests was primarily based on brightness artificats induced by the filters, whereas the degraded performance on the other tests was due to the absorption of short- to midwavelength light by the filters. A slight majority (56%) of the subjects rated the filters as being moderate to highly effective in improving their color discrimination. Nevertheless, only 17% were interested in actually purchasing a pair. Common reasons for rejecting the filters were the color distortions produced by the red filters and fewer colors were actually perceived when wearing the filters.

Adolescent↗

PubMed1997

Eye color changes past early childhood. The Louisville Twin Study.

OBJECTIVE: To determine whether eye color changes after 6 years of age. DESIGN: Longitudinal data on eye color were obtained from the Louisville Twin Study, Louisville, Ky. Twins (n = 1513 [individuals]) were assessed at least once and most twins (n = 1386) were examined on 2 or more occasions. Parents of twins were also examined at the study inception, 128 of whom were assessed again from February 1989 to October 1993. MAIN OUTCOME MEASURE: Eye color was assessed at each examination by matching the iridial coloration of the subject to 1 of 15 painted glass eye anterior segments, similar to those in artificial eyes, mounted on a circular disk. The spectrum ranged from light blue (1) to dark brown (15). RESULTS: Among whites (n = 1359), the eye color of 3.8% to 8.6% of the sample twins became 2 U or more darker or 2 U or more lighter during 3- to 9-year intervals between 6 years of age and adulthood (> 18 years, < 24 years). Among identical (monozygotic) twin pairs, there was a high degree of concordance in eye color (r = 0.98 [P < .001]), while in fraternal (dizygotic) twin pairs, the concordance was less pronounced (r = 0.49) and decreased with age (r = 0.07). Among the sample of the mothers of twins, 9% had irides that lightened by 2 U or more during the follow-up period. CONCLUSION: Most individuals achieve stable eye color by 6 years of age. However, a subpopulation of 10% to 15% of white subjects have changes in eye color throughout adolescence and adulthood in the eye color range that can be expected to reflect changes in iridial melanin content or distribution. These data also suggest that such changes in eye color, or the propensity to such changes, may be genetically determined.

Adolescent↗

PubMed2000

Clinical evaluation of contrast-enhanced color Doppler sonography in the differential diagnosis of liver tumors.

PURPOSE: We investigated the value of contrast-enhanced color Doppler sonography in the differential diagnosis of liver tumors. METHODS: We prospectively examined 105 focal liver lesions in 100 patients by real-time gray-scale sonography, color Doppler sonography, and contrast-enhanced color Doppler sonography with galactose-based microbubbles (SH U 508A; Levovist). The final diagnoses of the liver lesions as confirmed by pathology or additional imaging techniques were 31 metastases, 25 hemangiomas, 19 hepatocellular carcinomas, 19 focal nodular hyperplasias, 2 cholangiocellular carcinomas, and 9 other lesions. RESULTS: Vascularity could be detected in 43 (41%) of the 105 lesions by conventional color Doppler sonography compared to 67 (64%) by contrast-enhanced color Doppler sonography. Contrast-enhanced color Doppler sonography identified moderate or extensive vascularity in all 19 focal nodular hyperplasias, moderate or extensive vascularity in 16 hepatocellular carcinomas and both cholangiocellular carcinomas, and no or minor vascularity in all but 3 hemangioma. The combination of gray-scale, conventional color Doppler, and contrast-enhanced color Doppler sonography led to the correct diagnosis in 81% of cases (85 of 105), compared to 57% (60/105) for gray-scale and conventional color Doppler sonography and 31% (33/105) for gray-scale sonography alone. CONCLUSIONS: Contrast-enhanced color Doppler sonography improves the detection of tumor vascularity and is useful in the differential diagnosis of liver lesions.

Confidence Intervals↗

PubMed2005

Sugar concentration of fruits and their detection via color in the Central American spider monkey (Ateles geoffroyi).

Although most arguments explaining the predominance of polymorphic color vision in platyrrhine monkeys are linked to the advantage of trichromacy over dichromacy for foraging for ripe fruits, little information exists on the relationship between nutritional reward and performance in fruit detection with different types of color vision. The principal reward of most fruits is sugar, and thus it seems logical to investigate whether fruit coloration provides a long-distance sensory cue to primates that correlates with sugar content. Here we test the hypothesis that fruit detection performance via trichromatic color vision phenotypes provides better information regarding sugar concentration than dichromatic phenotypes (i.e., is a color vision phenotype with sufficient red-green (RG) differentiation necessary to "reveal" the concentration of major sugars in fruits?). Accordingly, we studied the fruit foraging behavior of Ateles geoffroyi by measuring both the reflectance spectra and the concentrations of major sugars in the consumed fruits. We modeled detection performance with different color phenotypes. Our results provide some support for the hypothesis. The yellow-blue (YB) color signal, which is the only one available to dichromats, was not significantly related to sugar concentration. The RG color vision signal, which is present only in trichromats, was significantly correlated with sugar content, but only when the latter was defined by glucose. There was in fact a consistent negative relationship between fruit detection performance and sucrose concentration, although this was not significant for the 430 nm and 550 nm phenotypes. The regular trichromatic phenotypes (430 nm, 533 nm, and 565 nm) showed higher correlations between fruit performance and glucose concentration than the other two trichromatic phenotypes. Our study documents a trichromatic foraging advantage in terms of fruit quality, and suggests that trichromatic color vision is advantageous over dichromatic color vision for detecting sugar-rich fruits.

Animals↗

PubMed2001

Endocrine mechanisms controlling body-color polymorphism in locusts.

The present article reviews recent published and unpublished findings on the hormonal mechanisms for the control of body-color polymorphism in locusts. Emphasis is placed on the dark color-inducing factors and their role in the induction of various types of body coloration observed under different environmental conditions. Implantation of corpora cardiaca (CC) taken from normal nymphs of Locusta migratoria induced dark color in nymphs of an albino strain. Using the albino strain for the bioassay, a neuropeptide, [His7]-corazonin, was identified as a dark color-inducing factor for L. migratoria and Schistocerca gregaria. In the former, depending upon the dose and timing of the injection, this peptide and juvenile hormone developed various body colors looking like those found in nature. The body coloration characteristic of gregarious forms was also induced in isolated albino nymphs and field-collected solitary nymphs. In S. gregaria, on the other hand, the peptide induced black patterns, but the orange or yellow background color observed in gregarious forms was not induced when the peptide was injected into solitary individuals. [His7]-corazonin also induced darkening in other grasshoppers and locusts, but not in katydids. Albino L. migratoria developed dark color when implanted with brains or CC taken from other insects belonging to 10 major insect orders, but not with those from Coleoptera. [His7]-corazonin or a similar compound is widespread among insects and plays a pivotal role in controlling body color in some species and presumably other physiological roles in other species. Arch.

Animals↗