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PubMed1978

Some observations in the fine structure of age changes of the mouse retinal pigment epithelium.

Age changes of the fine structure in the CF-1 mouse retinal pigment epithelium were studied from 1--24 months old. The change most characteristic of the senescence of the retinal pigment epithelium was found to be the appearance of wavy undulating 12nm wide filaments having a periodicity of about 80nm after the 12th month. In addition, the retinal pigment epithelial cells of the aging eye were found to have a marked accumulation of lysosomal dense bodies measuring about 0.3 to 1.2 micrometer in diameter especially in the apical portion of the cytoplasm. Extended and enlarged basal cytoplasmic infoldings of the retinal pigment epithelial cells were another prominent age change in the old mouse. In these basal infoldings densely fixed amorphous materials by tannic acid and very fine filaments are recognized. Age-related changes of the retinal pigment epithelial cell of the CF-1 mouse may take place as the degeneration of cytoplasmic materials, the appearance of bundles consisting of parallel undulating filaments, and the extending process of basal infolding from the choroid side.

Aging↗
PubMed1985

The visual pigment sensitivity hypothesis: further evidence from fishes of varying habitats.

Visual pigments were extracted from the retinas of 8 species of marine teleosts and 4 species of elasmobranchs and a comparison was made of the pigment properties from these fishes, some inhabiting surface waters, others from the mesopelagic zone, and a few migrating vertically between these two environments. An association was found between the spectral position of the absorbance curve and the habitat depth or habitat behavior, with the blue-shifted chrysopsins being the pigments of the twilight zone fishes and the rhodopsins with fishes living near the surface. The retina of the swell shark (Cephaloscyllium ventriosum) yielded extracts with two photopigments; one, a rhodopsin at 498 nm; the second, a chrysopsin at 478 nm. This fish has been reported to practice seasonal vertical migrations between the surface and the mesopelagic waters. In addition to the spectral absorbance, several properties of these visual pigments were examined, including the meta-III product of photic bleaching, regeneration with added 11-cis and 9-cis retinals, and the chromophoric photosensitivity. The chrysopsin properties were found to be fundamentally similar to those of typical vertebrate rhodopsins. Correlating the spectral data with the habitat and habitat behavior of our fishes gives us confidence in the idea that the scotopic pigments have evolved as adaptations to those aspects of their color environment that are critical to the survival of the species.

Animals↗
PubMed1978

Biliary lipid excretion in patients with pigment gallstones. A comparison with cholesterol gallstone patients.

Pigment gallstone patients are believed to have normal biliary lipid excretion. In order to measure this and to better understand cholesterol gallstone formation, the kinetics of biliary lipid excretion were studied in three patients who had been cholecystectomized for pigment gallstones and the results compared to those previously obtained in patients cholecystectomized for cholesterol gallstone. Pigment-stone patients had hyperbolic relationships between cholesterol and phospholipid outputs and bile salt output which were similar to those seen in cholesterol-stone patients. However, pigment-stone patients excreted more cholesterol and phospholipid at high bile salt output but approached those levels more gradually than cholesterol-stone patients. As a result, pigment-stone patients produced bile undersaturated with cholesterol at a lower bile salt output than cholesterol-stone patients, and thus they would be less likely to produce supersaturated bile during low bile salt output such as that occurring during an overnight fast. The data suggest that cholesterol-stone patients, in addition to excreting more cholesterol and less bile salts than normals, have a defect in the rate of lipid output in response to decreasing bile salt output.

Adult↗
PubMed1975

On the evolution of the photosynthetic pigments.

During the course of terrestrial evolution, some organisms developed the capability of capturing and utilizing solar radiation. Colored compounds were undoubtedly incorporated within living forms from the earliest times, but during the transition from heterotrophic to a photoautotrophic metabolism only those pigments were selected that were components of the evolving photosynthetic apparatus and were able to catalyze reactions involving storage of light energy in chemical bonds. In this communication, some properties of tetrapyrroles with a closed porphyrin ring containing a metal ion in the center are discussed. These compounds are present in all principal contemporary photosynthetic pigments, and their synthesis has been demonstrated from simpler compounds under prebiotic conditions. It is probable that during intermediate stages in the evolution of photosynthesis, pigments with oxidizing potentials lower than that of chlorophyll were utilized to store light energy although they were not capable of removing electrons from water. The evolution and function of multiple forms of a given photosynthetic pigment in vivo are discussed. 'Accessory' pigments may be regarded as rudiments of the evolutionary development of the photosynthetic apparatus.

Bacteriochlorophylls↗
PubMed1996

Hypercholeresis with cholate infusion in dogs with pigment gallstones.

We previously reported that dogs with pigment gallstones infused with taurocholate produce higher bile flow than normal dogs due to an increase in bile-acid independent bile flow. Since dogs with pigment gallstones are taurine-depleted and secrete large amounts of unconjugated bile salt, we hypothesized that the observed increased bile flow is secondary to the presence of unconjugated bile salts in the biliary tract, and cholate infusion was compared in normal and pigment gallstone dogs. Cholate increased bile flow significantly (P < 0.05) from 5.2 and 8.2 to 31 and 57 microliter/kg/min in normal and pigment gallstones dogs, respectively. Plots of bile flow versus bile acid output yielded separate linear relationships with a higher slope in gallstone dogs, but mannitol clearance indicated that excess flow originated in the canaliculus. Extended cholate infusion (570 min) severely taurine depleted normal dogs and increased cholate secretion, but bile flow remained significantly lower (P < 0.05) in normal dogs than in gallstone dogs. Choleretic activity of cholate in normal dogs was similar to that of taurocholate, but was nearly twice that of taurocholate in gallstone dogs. Choleretic activity increased in both groups with extended cholate infusion, suggesting adaptive changes in a biliary system bathed with unconjugated bile salts. These results are important since the increased bile flow in dogs with pigment gallstones would increase delivery of all biliary components to the gallbladder contributing to the high concentrations of gallbladder bile calcium previously observed in these dogs. It also has important physiological implications concerning the formation of bile in the proximal biliary tree. The data are most consistent with either direct hepatocyte stimulation to secrete another anion or with cholate/anion exchange at the canalicular, rather than ductal, level.

Animals↗
PubMed2002

Isolation and identification of Streptomyces sp. and assay of its exocellular water-soluble blue pigments.

A bacterial strain producing a great amount of blue pigment during submerse fermentation was isolated and identified. Based on morphological characteristics, cell-wall chemotype and sequence of 16S rRNA gene, the strain should belong to the genus Streptomyces; it had 99.4% homology of 16S rRNA gene sequence with that of Streptomyces indigocolor. The pigment production by the strain was affected by carbon and nitrogen sources. The main components of the pigment mixture (detected by HPLC and TLC) were tentatively classified as actinorhodin-related compounds. The pigment was relatively stable against light and higher temperature but was sensitive to low pH. The preliminary acute-toxicity determination showed that the pigment was nontoxic (LD50 > 15 mg/g).

Animals↗
PubMed2000

Distinct requirements for the AP-3 adaptor complex in pigment granule and synaptic vesicle biogenesis in Drosophila melanogaster.

The AP-3 adaptor protein complex has been implicated in the biogenesis of lysosome-related organelles, such as pigment granules/melanosomes, and synaptic vesicles. Here we compare the relative importance of AP-3 in the biogenesis of these organelles in Drosophila melanogaster. We report that the Drosophila pigmentation mutants orange and ruby carry genetic lesions in the sigma3 and beta3-adaptin subunits of the AP-3 complex, respectively. Electron microscopy reveals dramatic reductions in the numbers of electron-dense pigment granules in the eyes of these AP-3 mutants. Mutant flies also display greatly reduced levels of pigments housed in these granules. In contrast, electron microscopy of retinula cells reveals numerous synaptic vesicles in both AP-3 mutant and wild-type flies, while behavioral assays show apparently normal locomotor ability of AP-3 mutant larvae. Together, these results demonstrate that Drosophila AP-3 is critical for the biogenesis of pigment granules, but is apparently not essential for formation of a major population of synaptic vesicles in vivo.

Adaptor Protein Complex alpha Subunits↗
PubMed2001

The effects of a diode laser (810 nm) on pigmented guinea-pig skin.

Various types of lasers, such as the Q-switched ruby laser and the Alexandrite laser, cause selective damage to cutaneous pigmented cells and are currently used in the therapy of pigmented lesions. The aim of this study was to evaluate the effects of a diode laser at a wavelength of 810 nm on pigmented guinea-pig skin. The diode laser was supplied by OcuLight Iris Medical Instruments, Inc. and was used to deliver 0.15, 0.2, 0.3, 0.4, 0.5, 1 and 1.5 J/cm2 laser beams in micropulses of 100 micros. The study was carried out on albino and black-spotted guinea pigs (GP). After irradiation, punch biopsies were taken and analysed by light and electron microscopy. Albino animals developed just a few signs of cutaneous injury. This mostly consisted of spongiotic disarray, after the highest doses were administered (>1 J/cm2). In the black skin of spotted GPs alterations appeared at 0.15 J/cm2 and included melanosome damage and, at doses higher than 0.3 J/cm2, also melanocyte damage. These observations demonstrate that the diode laser at 810 nm selectively affects pigmented structures and that the cellular targets of diode laser radiation are the melanosomes. The diode laser specificity for melanin may provide a biological basis for the treatment of pigmented superficial cutaneous lesions.

Animals↗
PubMed1996

[Amiodarone pigmentation].

Amiodarone can occasionally lead to a slate-coloured pigmentation in chronically UV-expose skin. A 63 year old patient presented with a pruritic bluish-purple pigmentation of the face 2 years after taking 400 mg of amiodarone daily for 2 years. During the 24 months after the dose was reduced to 200 mg daily, the pigmentation remained unchanged. Amiodarone pigmentation is caused by the UV-induced accumulation of lipofuscin in dermal macrophages, depending on both the daily dose and the duration of therapy. In the differential diagnosis, pigmentation caused by other drugs is the main consideration. Cessation of therapy eventually leads to complete normalization of skin colour.

Amiodarone↗
PubMed2005

Molecular characterization of durum and common wheat recombinant lines carrying leaf rust resistance (Lr19) and yellow pigment (Y) genes from Lophopyrum ponticum.

Chromosome 7E from Lophopyrum ponticum carries a valuable leaf rust resistant gene designated Lr19. This gene has not been widely used in common wheat breeding because of linkage with the yellow pigment gene Y. This gene tints flour yellow, reducing its appeal in bread making. However, a high level of yellow pigment is desirable in durum wheat breeding. We produced 97 recombinant chromosomes between L. ponticum transfer 7D.7E#1 and its wheat homoeologues, using the ph1b mutation that promotes homoeologous pairing. We characterized a subset of 37 of these lines with 11 molecular markers and evaluated their resistance to leaf rust and the abundance of yellow pigment. The Lr19 gene was mapped between loci Xwg420 and Xmwg2062, whereas Y was mapped distal to Xpsr687, the most distal marker on the long arm of chromosome 7. A short terminal 7EL segment translocated to 7A, including Lr19 and Y (line 1-23), has been transferred to durum wheat by backcrossing. The presence of this alien segment significantly increased the abundance of yellow pigment. The Lr19 also conferred resistance to a new durum leaf rust race from California and Mexico that is virulent on most durum wheat cultivars. The new durum lines with the recombinant 7E segment will be useful parents to increase yellow pigment and leaf rust resistance in durum wheat breeding programs. For the common wheat breeding programs, we selected the recombinant line 1-96, which has an interstitial 7E segment carrying Lr19 but not Y. This recombinant line can be used to improve leaf rust resistance without affecting flour color. The 7EL/7DL 1-96 recombinant chromosome did not show the meiotic self-elimination previously reported for a 7EL/7BL translocation.

Basidiomycota↗
PubMed2003

The glutathione-mediated detoxification pathway in yeast: an analysis using the red pigment that accumulates in certain adenine biosynthetic mutants of yeasts reveals the involvement of novel genes.

The glutathione-mediated pathway for the detoxification of endogenously and exogenously derived toxic compounds was investigated using a pigment that accumulates in certain adenine biosynthetic mutants of yeasts. The ade1 / ade2 mutants of Saccharomyces cerevisiae, when grown on adenine-limiting medium, accumulate a characteristic red pigment (ade pigment) in their vacuoles. The precursors of the ade pigments are toxic intermediates that form conjugates with glutathione, followed by their transport inside the vacuole. In this study, this red pigment was used as a phenotypic screen to obtain insight regarding new genes involved in the three phases of this detoxification pathway: the activation phase (phase I), the conjugation phase (phase II), and the efflux phase (phase III). Components of the phase III (efflux) pathway which includes, in addition to the previously characterized Ycf1p and Bpt1p, another member of the 'Ycf1p family', Bat1p, as well as a vacuolar H(+)-ATPase-dependent transport were identified. In the investigation of phase II (conjugation), it was found that glutathione S-transferases, encoded by GTT1 and GTT2,do not appear to play a role in this process. By contrast, two other previously characterized genes, the oxidative stress transcription factor gene, SKN7, and the yeast caesin protein kinase gene, YCK1, of S. cerevisiae do participate in this pathway.

Adenine↗
PubMed2005

Analysis of cyanobacterial pigments and proteins by electrophoretic and chromatographic methods.

Cyanobacteria are a diverse and ubiquitous group of prokaryotes with several unifying features. Amongst these is the macromolecular structure known as the phycobilisome, which is composed of water-soluble phycobiliproteins covalently bound by linker peptides or proteins in a configuration designed to optimize energy transfer to the photosynthetic reaction center of the organism. Phycobiliproteins are highly fluorescent by virtue of their covalently bound, linear tetrapyrrole chromophores known as bilins. Analysis of these prosthetic pigments, along with other non-water soluble pigments, such as the chlorophylls and carotenoids, can provide insight into microbial diversity. The effects of environmental growth conditions and stresses can also be probed by measuring pigment and protein concentrations. This review will focus, therefore, on applications of various chromatographic and electrophoretic methods for the analysis of cyanobacterial pigment and protein constituents. Although the greatest emphasis will be placed on the measurement of bilins and phycobiliproteins, this review will also consider other pigments and proteins important to cyanobacterial growth and survival, such as chlorophyll a, carotenoids, ectoenzymes, linker and membrane proteins, and extracellular proteins.

Chromatography↗
PubMed2001

Visual pigments and optical habitats of surfperch (Embiotocidae) in the California kelp forest.

We studied the optical microhabitat use and visual pigment variation among a group of closely related teleosts (surfperch: Embiotocidae) living along the nearshore central California coast. We employed a diver-operated spectroradiometer to record the optical microhabitat use of eight surfperch species in Monterey Bay. and microspectrophotometry to measure visual pigment absorbance for nine surfperch species. Species were dichromatic with mixtures of A1- and A2-based visual pigments exhibiting extensive maximum absorbance (lambda(max)) variation across species: 455-482 nm for SWS cones and 527-546 nm for LWS cones. Interspecific variation in sidewelling irradiance measurements (mean lambdaFmaxs) significantly accounted for 63% of the variation in surfperch LWS visual pigments and 83% of the interspecific variation in SWS visual pigments using a phylogenetically-corrected regression technique. Optimality models for maximizing relative photon capture of background radiance demonstrate that the LWS cone lambda(max) values are tuned for maximizing photon capture of the species-specific horizontal visual field, while the SWS cone lambda(max), are well offset from the dominant background radiance. This study is one of the first to demonstrate species-specific differences in habitat usage at microhabitat scales accounting for differences in photoreceptor peak absorbance among closely related, sympatric species.

Animals↗
PubMed2005

The cone photoreceptors and visual pigments of chameleons.

Visual pigments, oil droplets and photoreceptor types in the retinas of four species of true chameleons have been examined by microspectrophotometry. The species occupy different photic environments: two species of Chamaeleo are from Madagascar and two species of Furcifer are from Africa and the Arabian Peninsula. In addition to double cones, four spectrally distinct classes of single cone were identified. No rod photoreceptors were observed. The visual pigments appear to be mixtures of rhodopsins and porphyropsins. Double cones contained a pale oil droplet in the principle member and both outer segments contained a long-wave-sensitive visual pigment with a spectral maximum between about 555 nm and 610 nm, depending on the rhodopsin/porphyropsin mixture. Long-wave-sensitive single cones contained a visual pigment spectrally identical to the double cones, but combined with a yellow oil droplet. The other three classes of single cone contained visual pigments with maxima at about 480-505, 440-450 and 375-385 nm, combined with yellow, clear and transparent oil droplets respectively. The latter two classes were sparsely distributed. The transmission of the lens and cornea of C. dilepis was measured and found to be transparent throughout the visible and near ultraviolet, with a cut off at about 350 nm.

Animals↗
PubMed2005

Visual pigment spectra of the comma butterfly, Polygonia c-album, derived from in vivo epi-illumination microspectrophotometry.

The visual pigments in the compound eye of the comma butterfly, Polygonia c-album, were investigated in a specially designed epi-illumination microspectrophotometer. Absorption changes due to photochemical conversions of the visual pigments, or due to light-independent visual pigment decay and regeneration, were studied by measuring the eye shine, i.e., the light reflected from the tapetum located in each ommatidium proximal to the visual pigment-bearing rhabdom. The obtained absorbance difference spectra demonstrated the dominant presence of a green visual pigment. The rhodopsin and its metarhodopsin have absorption peak wavelengths at 532 nm and 492 nm, respectively. The metarhodopsin is removed from the rhabdom with a time constant of 15 min and the rhodopsin is regenerated with a time constant of 59 min (room temperature). A UV rhodopsin with metarhodopsin absorbing maximally at 467 nm was revealed, and evidence for a blue rhodopsin was obtained indirectly.

Animals↗
PubMed2006

In vivo confocal microscopy of pigmented conjunctival tumors.

PURPOSE: To analyze the appearance of conjunctival pigmented tumors as seen by in vivo confocal microscopy. METHODS: Twenty-eight pigmented conjunctival tumors including 6 nevi, 13 acquired melanoses, 7 conjunctival melanomas, and 2 extrascleral growths of uveal melanomas were examined by in vivo confocal microscopy using the Heidelberg Retina Tomograph (HRTII)/Rostock Cornea Modul (RCM). Confocal images were analyzed using predefined criteria by an observer masked to final histological diagnosis and a preliminary diagnosis was established. After excision, histology and immunohistochemistry using antibodies against S-100, Melan-A, HMB-45, Ki-67, CD3, and CD68 were performed in all specimens and compared with in vivo confocal images of the same lesions. RESULTS: Confocal microscopy images confirmed typical histopathological features of conjunctival pigmented tumors. Nest or diffuse collections of medium-sized uniform hyper- or hyperreflective cells in the stroma and stromal cysts lined with a multilayered epithelium were visible in 100% of conjunctival nevi. Small dendritic cells were typically observed in 100% of primary acquired melanoses (PAM) without atypia and in 2 out of 6 nevi. Large networks of hyperreflective dendritic cells were present in 100% of PAM with atypia. Whereas images of PAM without atypia and secondary complexion-associated melanosis showed hyperreflective granules confined to the basal epithelium in 67% of lesions, PAM with atypia presented with hyperreflective granules and patches throughout the epithelium in all cases. Malignant melanomas of the conjunctiva and extrascleral growths of uveal melanomas demonstrated large hyperreflective cells with prominent nuclei and nucleoli. In vivo confocal microscopy showed a sensitivity of 89% and a specificity of 100% to establish the correct diagnosis of conjunctival melanoma compared with histology. CONCLUSIONS: High correlations were found between in vivo confocal microscopy using near-infrared laser light and histology in the diagnosis of pigmented conjunctival lesions. In vivo confocal microscopy seems to be a valuable new tool in the differential diagnosis and follow-up of pigmented conjunctival tumors. It does not replace histology, but may assist in performing guided biopsy in tumors suspected clinically and/or with in vivo microscopy. In addition, in vivo confocal microscopy may support the clinical diagnosis of extrascleral involvement in uveal melanoma.

Adolescent↗
PubMed2006

Identifying genes underlying skin pigmentation differences among human populations.

Skin pigmentation is a human phenotype that varies greatly among human populations and it has long been speculated that this variation is adaptive. We therefore expect the genes that contribute to these large differences in phenotype to show large allele frequency differences among populations and to possibly harbor signatures of positive selection. To identify the loci that likely contribute to among-population human skin pigmentation differences, we measured allele frequency differentiation among Europeans, Chinese and Africans for 24 human pigmentation genes from 2 publicly available, large scale SNP data sets. Several skin pigmentation genes show unusually large allele frequency differences among these populations. To determine whether these allele frequency differences might be due to selection, we employed a within-population test based on long-range haplotype structure and identified several outliers that have not been previously identified as putatively adaptive. Most notably, we identify the DCT gene as a candidate for recent positive selection in the Chinese. Moreover, our analyses suggest that it is likely that different genes are responsible for the lighter skin pigmentation found in different non-African populations.

Asian People↗
PubMed1999

Evidence of decreased adhesion between the neural retina and retinal pigmented epithelium of the Mitfvit (vitiligo) mutant mouse.

In order for the retina to function properly, photoreceptor cell outer segments must be in contact with the adjacent retinal pigmented epithelium (RPE). A mouse model homozygous for the vitiligo mutation of the microphthalmia (Mitf) gene manifests disruption of the outer segment/RPE interdigitation and demonstrates progressive loss of the photoreceptor cells. The mouse nevertheless has near normal levels of rhodopsin for many weeks and it is not known whether there is an in vivo loss of adhesion or whether the disruption is visible following tissue processing for histology. To assess this, a mechanical separation experiment was performed in which neural retinas were peeled free from the RPE and examined for the amount of pigment adherent to them. The peeling experiment indicated that control neural retinas retained significant amounts of adherent pigment at all ages examined. Neural retinas of mutant mice at age 2 weeks demonstrated adherent pigment, but older animals retained minimal pigment. Scanning electron microscopy indicated that the RPE cells of control mice were markedly damaged upon peeling and displayed different planes of cleavage, whereas those of mutants showed minimal cellular damage upon peeling, suggestive of decreased adhesion. A recombination experiment revealed that the mutant RPE/eyecup could reappose mutant and control retinas under in vitro conditions, suggesting that RPE fluid transport abilities were intact. The data provide the first direct experimental evidence that the Mitfvit mutant mouse has a naturally occurring retinal detachment and hence support its value as a model for studies of retina/RPE adhesion.

Animals↗