SEARCH · Search PubMed

Results for “PIGMENTATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources

PubMed2005

The influence of long-term chromatic adaptation on pigment cells and striped pigment patterns in the skin of the zebrafish, Danio rerio.

The striped pigment patterns in the flanks of zebrafish result from chromatophores deep within the dermis or hypodermis, while superficial melanophores associated with dermal scales add a dark tint to the dorsal coloration. The responses of these chromatophores were compared during the long-term adaptation of zebrafish to a white or a black background. In superficial skin, melanophores, xanthophores, and two types of iridophores are distributed in a gradient along the dorso-ventral axis independent of the hypodermal pigment patterns. Within one week the superficial melanophores and iridophores changed their density and/or areas of distribution, which adopted the dorsal skin color and the hue of the flank to the background, but did not affect the striped pattern. The increases or decreases in superficial melanophores are thought to be caused by apoptosis or by differentiation, respectively. When the adaptation period was prolonged for more than several months, the striped color pattern was also affected by changes in the width of the black stripes. Some black stripes disappeared and interstripe areas were emphasized with a yellow color within one year on a white background. Such long-term alteration in the pigment pattern was caused by a decrease in the distribution of melanophores and a concomitant increase in xanthophores in the hypodermis. These results indicate that morphological responses of superficial chromatophores contribute to the effective and rapid background adaptation of dorsal skin and while prolonged adaptation also affects hypodermal chromatophores in the flank to alter the striped pigment patterns.

Adaptation, Physiological↗

PubMed1978

Investigations of the pigments from Cytophaga johnsonae Cy jl. New flexirubin-type pigments.

Besides carotenoids a complex of flexirubin-type pigments was isolated from the gliding bacterium Cytophaga johnsonae Cy jl and separated into 6 components, which partly containe chlorine. In spite of the fact that these components still consist of pigment mixtures, the gross structures of 18 new flexirubin-type pigments could be deduced by spectroscopic and chemical investigations. The results open insights into biosynthesis and structural variety of the flexirubins, the novel non-isoprenoid pigments recently found in Flexibacter elegans.

Chemical Phenomena↗

PubMed1984

Chromatographic resolution of the rod pigment from the four cone pigments of the chicken retina.

Chicken rod and cone pigments are chromatographically resolved using a combination of stepwise elution from a concanavalin A affinity column and a secondary ion exchange purification. The rod pigment rhodopsin and the cone pigment iodopsin are purified to homogeneity. There is a partial separation of three other cone pigments: chicken green, chicken blue, and chicken violet, making clear that this is at least a tetrachromatic cone system.

Animals↗

PubMed1999

Retinal pigment epithelium pigment granules stimulate the photo-oxidation of unsaturated fatty acids.

The cellular pigments of the retinal pigment epithelium (RPE) have been shown to catalyze free radical activity, especially when illuminated with visible or ultraviolet light. This activity is sufficient to cause photooxidation of several major cellular components. The present investigation determined the relative ability of melanin, lipofuscin, and melanolipofuscin granules isolated from human and bovine eyes to oxidize polyunsaturated fatty acids, specifically linoleic and docosahexaenoic acids. The dark reactivity as well as the light-stimulated reactions were determined. The production of hydroperoxide derivatives of the linoleic and docosahexaenoic acids were determined by NADPH oxidation coupled to the activity of glutathione peroxidase, and also by production of thiobarbituric acid reactive substances. All RPE pigment granules stimulated fatty acid oxidation when irradiated with short wavelength (< 550 nm) visible light, with the melanosomes exhibiting the greatest light-induced activity. Only lipofuscin granules, however, caused peroxidation of fatty acids in the dark. These findings provide additional support for the role of RPE pigments in "blue light toxicity" as well as indicating that accumulation of lipofuscin may contribute to increased photooxidation in the aging RPE.

Animals↗

PubMed1990

Pigmented lesions of the retinal pigment epithelium and familial adenomatous polyposis.

Bilateral pigmented fundus lesions were found in 65 out of 72 patients with familial adenomatous polyposis, an additional five patients having unilateral lesions. With a family history of familial adenomatous polyposis, the occurrence of multiple bilateral fundus lesions indicates the presence of the abnormal gene, as does the occurrence of oval pigmented lesions with surrounding pale haloes. The absence of pigmented fundus lesions does not exclude the abnormal genotype, while the presence of occasional pigmented spots can be found in an appreciable percentage of the population. Ocular examination would, however, appear to be valuable in screening those at risk, with a positive yield in most carriers of the gene for familial adenomatous polyposis.

Adenomatous Polyposis Coli↗

PubMed1998

Early embryonic interaction of retinal pigment epithelium and mesenchymal tissue induces conversion of pigment epithelium to neural retinal fate in the silver mutation of the Japanese quail.

The neural retina and retinal pigment epithelium (RPE) diverge from the optic vesicle during early embryonic development. They originate from different portions of the optic vesicle, the more distal part developing as the neural retina and the proximal part as RPE. As the distal part appears to make contact with the epidermis and the proximal part faces mesenchymal tissues, these two portions would encounter different environmental signals. In the present study, an attempt has been made to investigate the significance of interactions between the RPE and mesenchymal tissues that derive from neural crest cells, using a unique quail mutant silver (B/B) as the experimental model. The silver mutation is considered to affect neural crest-derived tissues, including the epidermal melanocytes. The homozygotes of the silver mutation have abnormal eyes, with double neural retinal layers, as a result of aberrant differentiation of RPE to form a new neural retina. Retinal pigment epithelium was removed from early embryonic eyes (before the process began) and cultured to see whether it expressed any phenotype characteristic of neural retinal cells. When RPE of the B/B mutant was cultured with surrounding mesenchymal tissue, neural retinal cells were differentiated that expressed markers of amacrine, cone or rod cells. When isolated RPE of the B/B mutant was cultured alone, it acquired pigmentation and did not show any property characteristic of neural retinal cells. The RPE of wild type quail always differentiated to pigment epithelial cells. In the presence of either acidic fibroblast growth factor (aFGF) or basic FGF (bFGF), the RPE of the B/B mutant differentiated to neural retinal cells in the absence of mesenchymal tissue, but the RPE of wild type embryos only did so in the presence of 10-40 times as much aFGF or bFGF These observations indicate that genes responsible for the B/B mutation are expressed in the RPE as well as in those cells that have a role in the differentiation of neural crest cells. They further suggest that development of the neural retina and RPE is regulated by some soluble factor(s) that is derived from or localized in the surrounding embryonic mesenchyme and other ocular tissues, and that FGF may be among possible candidates.

Animals↗

PubMed2006

Indirect antioxidant protection against photooxidative processes initiated in retinal pigment epithelial cells by a lipofuscin pigment.

Oxidative mechanisms are considered to contribute to the aging changes in retinal pigment epithelial (RPE) cells that underlie the pathogenesis of age-related macular degeneration. An important source of oxidative damage is likely to be the photoreactive pigments that progressively accumulate and constitute the lipofuscin of retinal pigment epithelial cells. Evidence for a link between RPE lipofuscin and cellular dysfunction is also provided by the understanding of disease progression in Stargardt disease. Using a culture model previously used to demonstrate photooxidative damage to retinal pigment epithelial cells that have accumulated the lipofuscin fluorophore A2E, it was shown that the propensity for cell death is increased under conditions that deplete cellular levels of glutathione. Additionally, sulforaphane, a phytochemical and inducer of phase 2 enzymes, protected RPE cells that accumulated A2E and were irradiated at 430 nm. The protection afforded by sulforaphane was paralleled by elevated levels of glutathione and increases in the activities of the phase 2 enzymes NAD(P)H:quinone reductase and glutathione-S-transferases. Moreover, transcriptional induction of NAD(P)H:quinone reductase was indicated by the increases in mRNA determined by real time RT-PCR. There has been considerable interest in the intake of carotenoids and antioxidant vitamins and the related incidence of age-related macular degeneration. The present results indicate that the indirect antioxidant activity of plant-derived phase 2 inducers also may be potentially important.

Antioxidants↗

PubMed2006

Cloning and characterization of Enterobacter sakazakii pigment genes and in situ spectroscopic analysis of the pigment.

Enterobacter sakazakii is considered an opportunistic foodborne pathogen that is characterized by formation of yellow-pigmented colonies. Because of the lack of basic knowledge about Enterobacter sakazakii genetics, the BAC approach and the heterologous expression of the pigment in Escherichia coli were used to elucidate the molecular structure of the genes responsible for pigment production in Enterobacter sakazakii strain ES5. Sequencing and annotation of a 33.025 bp fragment revealed seven ORFs that could be assigned to the carotenoid biosynthesis pathway. The gene cluster had the organization crtE-idi-XYIBZ, with the crtE-idi-XYIB genes putatively transcribed as an operon and the crtZ gene transcribed in the opposite orientation. The carotenogenic nature of the pigment of Enterobacter sakazakii wt was ascertained by in situ analysis using visible microspectroscopy and resonance Raman microspectroscopy.

Carotenoids↗

PubMedDate not supplied

Fast assessment of the central macular pigment density with natural pupil using the macular pigment reflectometer.

We built a new macular pigment reflectometer (MPR) for fast and objective measuring of the optical density of macular pigment in the human eye, using the undilated eye. The design is based on the spectral reflectance from a spot of white light at the fovea. To evaluate its performance, we measured the macular pigment of 20 healthy subjects, ages 18 to 79 years, under four conditions: (1) natural pupil in the dark, (2) natural pupil with dim room light, (3) dilated pupil in the dark, and for comparison with a different technique, (4) heterochromatic flicker photometry (HFP) in dim room light with natural pupil. Condition 1 was repeated in a subset of 10 subjects after an interval of at least 3 days. Data analysis with a model of reflectors and absorbers in the eye provided the density of the macular pigment in conditions 1 to 3. Dim room light and pupil dilatation had no influence on measured density. Mean within subjects variation was typically 7%. Mean difference between test and retest after at least 3 days was 1%. Correlation between MPR and HFP was r=0.56 (p=0.012). Mean within subjects variation with HFP was 19%. The new instrument holds promise for specific applications such as epidemiological research.

Computer Systems↗

PubMed1993

Carney's complex with primary pigmented nodular adrenocortical disease and spotty pigmentations.

Carney's complex is composed of myxoma, spotty pigmentation and endocrine overactivity. A 27-year-old male was diagnosed to have Carney's complex on the basis of intense spotty pigmentations on his face, soles and palms, and bilateral adrenal nodular hyperplasia on computed tomography scanning (CT) and magnetic resonance imaging (MRI). Total bilateral adrenectomy was done; histological findings were compatible with primary pigmented adrenocortical disease (PPNAD). Recently, his sister and one of his brothers were suspected to have Carney's complex with PPNAD. We report the first familial case of Carney's complex with PPNAD and spotty pigmentations in Japan.

Adrenal Cortex Diseases↗

PubMed1975

[Accumulation of ephedrine, norephedrine, amphetamine and tyramine labeled with carbon 14 in pigmented and non-pigmented eyes in two races of rats].

The pigmented eyes of non albino rats (PVG) accumulated ephedrine, norephedrine and amphetamine. After 15 min accumulation of ephedrine and amphetamine was larger than of norephedrine. Autoradiographic studies showed that accumulation occurred in melanin containing iris and choroid and also in lacrymal glands which lack melanin. Accumulation of tyramine did not occur in eyes containing melanin. The non pigmented eyes of albino rats did not accumulate ephedrine, amphetamine, norephedrine and tyramine. It appeared that in pigmented eyes melanin was a site of loss of ephedrine, amphetamine and norephedrine; hence a smaller amount of drug will be available for interaction with adrenergic neurons and a smaller mydriatic effect will occur. Accumulation is possible only when metabolism is low, as observed with alpha-methylated amines. The four sympathomimetic amines used did not accumulate in the pigmented skin of black and white rats.

Amphetamine↗

PubMed1976

Studies on experimental malignant nerve sheath tumors maintained in tissue and organ culture systems. III. Melanin pigment and melanogenesis in experimental neurogenic tumors: a reappraisal of the histogenesis of pigmented nerve sheath tumors.

Four melanin pigment-containing intracranial tumors were found in three Long-Evans rats in the course of experimental oncogenesis by transplacental ethylnitrosourea (ENU). One of them was a leptomeningeal melanoma. Aside from the presence of scattered melanin-pigmented cells, the other three had the typical histological features of ENU-induced malignant nerve sheath tumors. Two of the three tumors were studied by electron microscopy and in tissue and organ culture systems. One of them demonstrated progressive melanogenesis in vitro; the other failed to produce more melanin and showed increasing differentiation, with a Schwannoma-like pattern by light microscopy. Melanosomes and premelanosomes were identified in both tumors by electron microscopy; the other fine structural features were those of malignant Schwannomas. These observations are relevant to the controversy on the histogenesis of pigmented nerve sheath tumors occasionally encountered in man and on the relationship of these tumors to pigmented nevi. The findings in the present study support the view of Masson that neoplastic nerve sheath cells are capable of melanogenesis.

Animals↗

PubMed1989

Pigmented adenomatoid odontogenic tumour. Report of an undescribed case and review of the literature of pigmented intraosseous odontogenic lesions.

A pigmented adenomatoid odontogenic tumour occurring in the mandible of a 12-year-old Japanese girl is reported. In addition to the characteristic histopathologic features, fine granules and coarse aggregates of melanin pigment were widely distributed in the spindle-shaped epithelial cells between duct-like structures, and dendritic cells containing melanin pigment were also distributed in tumour epithelium. The possible histogenesis of melanin pigment in the epithelial cells of the odontogenic lesions is discussed, although no firm conclusions could be drawn.

Bone Neoplasms↗

PubMedDate not supplied

Morphometry of age pigment (lipofuscin) and of ceroid pigment deposits associated with vitamin E deficiency.

Consistent amounts of lipofuscin and of ceroid pigment associated with vitamin E deficiency are reported to represent morphological correlates of aging and increased oxidative stress. A reliable quantification of these yellow autofluorescent deposits is of critical biological significance, thus we carried out a computer-assisted morphometric study on the accumulation of lipofuscin in physiological aging and of ceroid pigment in vitamin E deficiency, respectively. The total area and the size distribution of lipofuscin or ceroid pigment deposits were measured in CA3 hippocampal pyramidal neurons of 6-, 12-, 18- and 25-month-old rats, as well as in vitamin E deficient animals of 18 months of age. An increase in the mean total area of lipofuscin and ceroid pigment was found in aging and in vitamin E deficiency. In both conditions, the proportion of large discrete deposits also increased. The similarity of changes observed in old and adult vitamin E deficient animals suggests that the underlying processes initiated by the absence of alpha-tocopherol from the diet of adult rats and in physiological aging may share some common mechanisms.

Journal Article↗

PubMed1996

Pigment-pigment interactions and energy transfer in the antenna complex of the photosynthetic bacterium Rhodopseudomonas acidophila.

BACKGROUND: Photosynthesis starts with the absorption of solar radiation by antenna pigment molecules. In purple bacteria these chromophores, (bacteriochlorophyll a and carotenoid) are embedded in the membrane; they are non-covalently bound to apoproteins which have the ability to modulate the chromophores' absorbing characteristics. The first structure of the bacterial antenna complex from Rhodopseudomonas acidophila, strain 10050, shows a ring of nonameric symmetry. Two concentric cylinders of apoproteins enclose the pigment molecules. The current resolution of the structure, to 2.5 A, allows us to begin to explore the mechanism of energy transfer among these pigments. RESULTS: The mechanism of energy transfer, from the short- to long-wavelength-absorbing pigments, is largely determined by the relative distances and orientations of the chromophores. In this paper we provide evidence that energy transfer between the B800 and B850 bacteriochlorophylls is largely via Förster induced dipole-dipole resonance. Strong Coulombic (exciton) coupling among the 18 short distanced chromophores in the B850 macrocycle is promoted by good alignment of the Qy dipoles. Singlet-singlet energy transfer from carotenoid to the B800 macrocycle appears to be minimal, with most of the energy transfer going to B850. The higher energy state of both chromophores dominates in more complex situations. CONCLUSIONS: The structure of the antenna complex not only shows Nature at its most aesthetic but also illustrates how clever and efficient the energy transfer mechanism has become, with singlet-singlet excitation being passed smoothly down the spectral gradient to the reaction centre.

Bacterial Proteins↗

PubMed2002

Pigment compositions, spectral properties, and energy transfer efficiencies between the xanthophylls and chlorophylls in the major and minor pigment-protein complexes of photosystem II.

Absorption, fluorescence, and fluorescence excitation spectra have been measured from CP26, CP29, and monomeric and trimeric LHCIIb light-harvesting complexes isolated from Photosystem II subchloroplast particles from spinach. The complexes were purified using a combination of isoelectric focusing and sucrose gradient ultracentrifugation. The chlorophyll (Chl) and xanthophyll pigment compositions were measured using high-performance liquid chromatography (HPLC). Using the pigment compositions from the HPLC analysis as a starting point, the absorption spectral profiles of the complexes have been reconstructed from the individual absorption spectra obtained for each of the pigments. Also, the fluorescence excitation spectra of the complexes have been deconvoluted. The data reveal the energy transfer efficiencies between Chl b and Chl a and between specific xanthophylls and Chl a in the complexes. The spectral analyses reveal the underlying features of the highly congested spectral profiles associated with the complexes and are expected to be beneficial to researchers employing spectroscopic methods to investigate the mechanisms of energy transfer between the pigments bound in these complexes.

Chlorophyll↗

PubMed1991

Photoregulation of the Cat2 and Cat3 catalase genes in pigmented and pigment-deficient maize: the circadian regulation of Cat3 is superimposed on its quasi-constitutive expression in maize leaves.

We have investigated the accumulation of Cat2 and Cat3 catalase transcripts in 6-7-day postimbibition leaves of normally pigmented and pigment-deficient maize seedlings under different light regimes. In seedlings of normal inbred maize lines Cat2 mRNA accumulates to significantly higher levels in either continuous light or a diurnal light/dark cycle than in continuous dark. In contrast to the high levels of the Cat2 message observed in their wild-type siblings, carotenoid-deficient mutants accumulate Cat2 mRNA at barely detectable levels. Mutants deficient in chlorophylls, but having normal carotenoid levels, accumulate normal levels of Cat2 mRNA. This suggests that both light and carotenoids are required for the normal accumulation of the Cat2 message. The steady-state level of Cat3 RNA exhibits a dramatic diurnal variation when seedlings are grown under a 24-hr light/dark cycle. We have previously shown that this variation is at the level of Cat3 gene transcription and is under the control of a novel circadian rhythm. In this study we show that both pigment-deficient mutants and their wild-type siblings exhibit the normal diurnal pattern of Cat3 RNA accumulation. This indicates that photosynthetic pigments, allelic variation, and genetic background do not directly affect the temporal pattern of Cat3 accumulation in leaves. We observed, however, that when normal plants are grown in either continuous light or continuous dark, the Cat3 transcript in leaves is present at uniformly high levels throughout the 24-hr sampling period.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Northern↗

PubMed1989

Light Quality and Irradiance Level Interaction in the Control of Expression of Light-Harvesting Complex of Photosystem II: Pigments, Pigment-Proteins, and mRNA Accumulation.

Effects of red and blue light at irradiances from 1.6 to 28.3 micromolar per square meter per second on chloroplast pigments, light-harvesting pigment-proteins associated with photosystem II, and the corresponding mRNA were evaluated in maize (Zea mays L.) plants (OP Golden Bantum) grown for 14 days under 14 hours light/10 hours dark cycles. Accumulation of pigments, pigment-proteins, and mRNA was less in blue than in red light of equal irradiance. The difference between blue and red light, however, varied as a function of irradiance level, and the pattern of this variation suggests irradiance-controlled activation/deactivation (switching) of blue-light receptor. The maximum reduction in blue light of mRNA and proteins associated with light-harvesting complex occurs at lower irradiance levels than the maximum reduction of chlorophylls a and b.

Journal Article↗