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PubMed1991

Molecules specific to pigment epithelial cells: expression during in situ development and in vitro lens transdifferentiation of chick embryo pigment epithelium.

The retinal pigment epithelium (PE) is a monolayer of cells and plays a vital role in the regulation of the neural retina. We prepared monoclonal antibodies directed against retinal PE cells to analyze the specificity and differentiation of these cells. Spleen cells from BALB/c mice immunized with chick embryo retinal PE cells were fused with myeloma cells. Seven independent monoclonal antibodies were obtained which specifically recognized PE cells but did not react with any other tissues examined. None of the monoclonal antibodies reacted with the choroid and skin of pigmented chicks, suggesting that these antigens were unrelated to melanogenesis. Two of the 7 antibodies reacted with the PE cells in the retina, ciliary body and iris; the remaining 5 antibodies were specific to the PE cells in the retina. In the process of in vitro lens transdifferentiation from PE cells, the distribution of an antigen detected by one monoclonal antibody changed from the cytoplasmic granules to the actin fibers and then its immunoreactivity declined. The other monoclonal antibodies did not react with the differentiated PE cells and transdifferentiated lens cells, suggesting that the antibodies might be specific to the PE cells in the differentiated state, both in vivo and in vitro. During the in situ developmental process, each monoclonal antibody began to be immunoreactive to future PE cells in the optic eye cup at various stages from 72 to 120 h. The molecules common to all types of PE cells were expressed earlier than those specific to PE cells of the retina. Future ciliary and iridial PE cells appeared to transiently express the molecules specific to the retinal PE cells before the tip of eye cup contacted the lens vesicle. These data suggest that the monoclonal antibodies established in this study are powerful probes for exploring the functions and differentiation of PE cells.

Actins↗

PubMed2005

Pigment-pigment interactions in PCP of Amphidinium carterae investigated by nonlinear polarization spectroscopy in the frequency domain.

Peridinin-chlorophyll a-protein (PCP) is a unique antenna complex in dinoflagellates that employs peridinin (a carotenoid) as its main light-harvesting pigment. Strong excitonic interactions between peridinins, as well as between peridinins and chlorophylls (Chls) a, can be expected from the short intermolecular distances revealed by the crystal structure. Different experimental approaches of nonlinear polarization spectroscopy in the frequency domain (NLPF) were used to investigate the various interactions between pigments in PCP of Amphidinium carterae at room temperature. Lineshapes of NLPF spectra indicate strong excitonic interactions between the peridinin's optically allowed S(2) (1Bu(+)) states. A comprehensive subband analysis of the distinct NLPF spectral substructure in the peridinin region allows us to assign peridinin subbands to the two Chls a in PCP having different S(1)-state lifetimes. Peridinin subbands at 487, 501, and 535 nm were assigned to the longer-lived Chl, whereas a peridinin subband peaking at 515 nm was detected in both clusters. Certain peridinin(s), obviously corresponding to the subband centered at 487 nm, show(s) specific (possibly Coulombic?) interaction between the optically dark S(1)(2A(g)(-)) and/or intramolecular charge-transfer (ICT) state and S(1) of Chl a. The NLPF spectrum, hence, indicates that this peridinin state is approximately isoenergetic or slightly above S(1) of Chl a. A global subband analysis of absorption and NLPF spectra reveals that the Chl a Q(y)-band consists of two subbands (peaking at 669 and 675 nm and having different lifetimes), confirmed by NLPF spectra recorded at high pump intensities. At the highest applied pump intensities an additional band centered at </=660 nm appears, suggesting-together with the above results-an assignment to a low-dipole moment S(0) --> S(1)/ICT transition of peridinin.

Animals↗

PubMed1979

[Differentiation and tumorigenicity of human malignant melanocytes. Comparative study of two "non pigmented" and pigmented lines from the same fibroblastoid cells].

A morphological, caryological and biochemical study of two established cell lines of human malignant melanocytes derived from the same original tumour, when compared with heterotransplantation results in nude Mice, showed that "non-pigmented" cells are more tumorigenic than pigmented cells. Differentiation and tumorigenicity, although concomitant, here seem to be two independent phenomena.

Animals↗

PubMed2002

[Photosynthetic pigment contents of different germplasm of Rehmannia glutinosa and the relationship between pigments and leaf color].

OBJECTIVE: To evaluate the germplasm of Rehmannia glutinosa on the basis of photosynthetic pigment contents (PPC). METHOD: 20 cultivars were planted on the same condition. On Oct. 23 and Sept. 25, 3 leaves per cultivar were collected on different plants, and 80 mg mesophyll was collected among upper lateral veins and was ground in 96% alcohol, and the supernatant was subjected to measure on a spectrophotometer (Angilent 8453). RESULT: The PPCs among cultivars were significantly different at a P < or = 0.01 level. The results of the measurements were similar. Chlolophyll a was the most abundant pigment, but varied to a great extent among different cultivars. 20 cultivars were divided into 9 homogeneous groups according to the contents of chlorophyll a by Duncan's multiple range test at P < or = 0.05. In addition, the content of chlorophyll a was closely related to leaf color. The cultivars with higher chlolophyll a had deep green leaves, and those with lower had yellow green or pale green leaves. CONCLUSION: PPC was an inherent character and an important index for the germplasm evaluation of R. glutinosa.

Chlorophyll↗

PubMed1983

The fate of the phagosome: conversion to 'age pigment' and impact in human retinal pigment epithelium.

Phagosomes are converted to phagolysosomes and then to residual bodies (also known as lipofuscin granules or age pigment). Lipofuscin granules of retinal pigment epithelial (RPE) cells of single human eyes were isolated and analysed for enzyme content and fluorescence spectra. The granules are low in lysosomal enzymes and they fluoresce yellow-gold. Thin layer chromatography reveals several separable constituents. Lipofuscin granules accumulate with age, the largest increase occurring after the first decade of life in humans. Macular RPE cells accumulate granules more than non-macular cells.

Adolescent↗

PubMed1980

Studies on the retina and the pigment epithelium in hereditary canine ceroid lipofuscinosis. III. Morphologic abnormalities in retinal neurons and retinal pigmented epithelial cells.

Studies of the retina in 6- and 22-month-old English setters with progressive blindness, ataxia, and muscle weakness demonstrated a marked accumulation of abnormal cytosomes within neurons and retinal pigmented epithelial cells. Ganglion cells contained abundant cytosomes with evenly spaced stacks of membranes; bipolar and amacrine cell cytosomes consisted of dense, amorphous material with closely spaced configurations of light and dark lines; cytosomes within photoreceptor cells contained faintly staining curved profiles. All three cytosomes resembled those previously reported in brain neurons of CCL dogs. In retinal pigmented epithelial cells, there were prominent accumulations of lamellar fragments, either free in the cytoplasm or incorporated into melanin granules. These retinal abnormalities are likely to be related to deficiences of peroxidase and defects of lipid peroxidation. The pathologic and biochemical changes seen in these dogs are similar in many respects to those reported in human patients with Batten disease. As such, these dogs provide a convenient model for the study disease mechanisms and for therapeutic approaches to blindness in Batten disease.

Animals↗

PubMed1993

Expression of the rasT24 oncogene in the ciliary body pigment epithelium and retinal pigment epithelium results in hyperplasia, adenoma, and adenocarcinoma.

We examined eye lesions in five lines of transgenic mice carrying the human rasT24 oncogene driven by the type I gamma glutamyl transferase (gamma GT) promoter. In three lines, hyperplasia developed as early as 11.5 days postconception in the outer neuroectodermal layer, which gives rise to ciliary body and retinal pigment epithelium. At birth, the eyes from many animals contained adenomas, and by day 27, mice developed invasive adenocarcinomas originating in the region of the ciliary body. Microphthalmia, cataracts, and chronic nongranulomatous inflammation involving the anterior and/or posterior segments of the eye were also found. gamma GT is detectable histochemically as early as 11.5 gestational days in the outer neuroectodermal layer and after birth is more abundant in the ciliary body than in the retinal pigment epithelium. Using a reverse transcriptase-polymerase chain reaction, we found that type I (but not types II or III) gamma GT RNA is made by the mouse eye; the gamma GT(I)rasT24 transgene transcription product was detected in the eyes of all five transgenic lines. The sequential progression of hyperplasia to invasive neoplasms in the ciliary body in response to gamma GT(I)rasT24 expression differs from the process in the kidney of these animals in which tubular hyperplasia and microadenomas with little evidence of progression are the major lesions.

Adenocarcinoma↗

PubMed1979

Intracellular distribution of dopa and 5-S-cysteinyldopa in pigment cells with minimal pigment formation.

The hypothesis that only melanosomal catecholic amino acids contribute to melanin formation was tested by studying adult bovine eyes in which pigment synthesis is considered to be low or absent. Dopa and 5-S-cysteinyldopa were investigated in different cell fractions of the choroid and retinal pigment epithelium of cattle. Most of the dopa and 5-S-cysteinyldopa was found in the cytoplasm and very little in the large granule fraction. The presence of cysteinyldopa in the adult eye is evidence of tyrosinase activity, but the catechol amino acids in the cytoplasm probably do not give rise to melanin formation. It is assumed that they instead are excreted from the cells.

Animals↗

PubMed2006

Regulation of two photosynthetic pigment-related genes during stress-induced pigment formation in the green alga, Dunaliella salina.

The expression of mRNAs coding for 1-deoxyxylulose-5-phosphate synthase (DXS) and phytoene synthase (PSY) were studied in Dunaliella salina grown under nitrogen-sufficient (NS) and nitrogen-limited (NL) conditions. Under NS conditions growth was 2.5 times higher than under NL conditions. No differences were found in chlorophyll a content per cell, and total carotenoid content per cell was 5.33 pg 1(-1) for the NS treatment and 7.76 pg 1(-1) for the NL. DXS transcripts exhibited diminished expression under NL conditions, peaking at day 15 of cultivation in both treatments. Simultaneously, PSY transcripts exhibited constant expression under both conditions. These results suggest that these genes play an important role in the balance of photosynthetic pigments during pigment accumulation.

Alkyl and Aryl Transferases↗

PubMed1987

Polyethylene-based high-performance liquid chromatography of chloroplast pigments: resolution of mono- and divinyl chlorophyllides and other pigment mixtures.

In addition to most chlorophylls and their derivatives, monovinyl and divinyl chlorophyll species were separated by high-performance liquid chromatography, using a polyethylene column and a simple elution with aqueous acetone. Peak retention and resolution of the pigment separation were greatly increased by increasing the polarity of the mobile phase and also by decreasing the column temperature. Polyethylene chromatography showed chlorophyll separation behavior similar to that of the octadecyl silica column, but it showed no adsorption of the pigment species containing free carboxylic acid groups, enabling the complete separation of chlorophylls and their derivatives. Polyethylene is a superior alternative stationary phase to the known reversed-phase materials for chlorophyll separation and analysis.

Acetone↗

PubMed1978

Analysis of the pigment content of an antenna pigment-protein complex from three strains of Rhodopseudomonas sphaeroides.

The pigment content of a B800-850 light-harvesting pigment-protein complex isolated from three different stains of Rhodopseudomonas sphaeroides has been determined. In each case the ratio of carotenoid to bacteriochlorophyll present is very nearly 1 : 3 an no specificity with regard to carotenoid type was observed. The fourth derivative of the infra-red absorption bands of the complex was determined and it is concluded that the minimal functional unit of B800-850 complex consists of 1 carotenoid molecule and three bacteriochlorophyll molecules. The data presented here, together with the previous study of Austin, (Austin, L.A. (1976) Ph.D. Thesis, University of California at Berkeley, Lawrence Berkeley Laboratory Report No. LBL 5512) suggest that the 800 nm absorption band represents one of these bacteriochlorophyll molecules while the remaining two bacteriochlorophylls are responsible for the 850 nm band. The absorption spectra and circular dichroism spectra of the complexes suggests that their structure has not been greatly altered during the purification.

Bacterial Chromatophores↗

PubMed2001

Pigment conformation and pigment-protein interactions in the reconstituted Lhcb4 antenna protein.

Resonance Raman spectra of the native Lhcb4 antenna protein are compared with those of a recombinant protein prepared by in vitro refolding of its polypeptide, over-expressed in Escherichia coli, with added pigments [Giuffra et al. (1996) Eur. J. Biochem. 238, 112-120]. The results indicate that the native pigment conformation is reproduced almost perfectly in the reconstituted protein, with only small differences which are attributed to a slight shift in the Soret absorption peak of two or more chlorophylls. This procedure therefore represents a model system for the investigation of site-directed mutant LHC proteins, which are otherwise very difficult to obtain.

Carotenoids↗

PubMed1999

Malignant melanoma with prominent pigment synthesis: "animal type" melanoma--a clinical and histological study of six cases with a consideration of other melanocytic neoplasms with prominent pigment synthesis.

Rare skin neoplasms in humans, comprising nodules of heavily melanized cells, mimic melanocytic neoplasms seen in horses and laboratory animals and thus are termed animal type melanomas. In part because of their rarity, behavior is unpredictable; many cases manifest a long indolent phase, and metastases are reportable. Over 6 years, the authors encountered nine skin and one lymph node biopsy specimens from six patients in whom light microscopy of formalin-fixed, paraffin-embedded tissue sections stained with hematoxylin and eosin showed melanocytic neoplasms with prominent pigment synthesis. Clinical follow-up was obtained by telephone contact with clinicians. There were three women, two men, and one boy, aged 9 to 85 years, whose lesions were described as blue-black nodules with irregular borders from 1.0 to 4.0 cm in size, located on the scalp, lower extremities, back, and sacrum. The dermatopathology comprised confluent dermal sheets of heavily melanized cells whose nuclei, where discernible, were large with irregularly thickened membranes, coarse chromatin, prominent, often spiculated nucleoli, and irregular parachromatinic clearing. Mitoses were infrequent. Four lesions had an epidermal component. One patient suffered metastases to regional lymph nodes, liver, and lungs with lethal effect, one experienced regional lymph node metastases but is still alive, one had local cutaneous metastases but was lost to follow-up, and one has a chest wall mass that has not yet been investigated. This rare dermal-based melanocytic neoplasm with prominent pigment synthesis, the animal type melanoma, has a biological behavior difficult to predict on morphological grounds. We advise complete excision with a 1.0- to 2.0-cm margin of normal skin and clinical investigation for regional or distant metastases.

Adolescent↗

PubMed2001

The electric charge of pigment granules in pigment cells.

Black pigment cells called melanophores change colour in response to environmental changes and have lately been studied as promising biosensors. To further elucidate the intracellular processes involved in the colour changes of these cells, and to find optimal biosensing principles, the electric charge of intracellular pigment granules, melanosomes, has been determined in vitro by electrophoresis. Melanosomes from the two extreme states in the cell colour change (aggregated and dispersed melanosomes) were measured. The charge was found to be -1.5 x 10(-16) and -1.7 x 10(-16) C, aggregated and dispersed melanosomes, respectively, without significant difference between the two conditions. This charge is of the same order of magnitude as the one of 1000 electrons. The origin of the melanosome charge, and the use of these findings in new biosensor principles, is discussed.

Animals↗

PubMed2001

Excitation trap approach to analyze size and pigment-pigment coupling: reconstitution of LH1 antenna of Rhodobacter sphaeroides with Ni-substituted bacteriochlorophyll.

Replacement of the central Mg in chlorophylls by Ni opens an ultrafast (tens of femtoseconds time range) radiationless de-excitation path, while the principal ground-state absorption and coordination properties of the pigment are retained. A method has been developed for substituting the native bacteriochlorophyll a by Ni-bacteriochlorophyll a ([Ni]-BChl) in the light harvesting antenna of the core complex (LH1) from the purple bacterium, Rhodobacter (Rb.) sphaeroides, to investigate its unit size and excited state properties. The components of the complex have been extracted with an organic solvent from freeze-dried membranes of an LH1-only strain of Rb. sphaeroides and transferred into the micelles of n-octyl-beta-glucopyranoside (OG). Reconstitution was achieved by solubilization in 3.4% OG, followed by dilution, yielding a complex nearly identical to the native one, in terms of absorption, fluorescence, and circular dichroism spectra as well as energy transfer efficiency from carotenoid to bacteriochlorophyll. By adding increasing amounts of [Ni]-BChl to the reconstitution mixture, a series of LH1 complexes was obtained that contain increasing levels of this efficient excitation trap. In contrast to the nearly unchanged absorption, the presence of [Ni]-BChl in LH1 markedly affects the emission properties. Incorporation of only 3.2 and 20% [Ni]-BChl reduces the emission by 50% and nearly 100%, respectively. The subnanosecond fluorescence kinetics of the complexes were monoexponential, with the lifetime identical to that of the native complex, and its amplitude decreasing in parallel with the steady-state fluorescence yield. Quantitative analysis of the data, based on a Poisson distribution of the modified pigment in the reconstituted complex, suggests that the presence of a single excitation trap per LH1 unit suffices for efficient emission quenching and that this unit contains 20 +/- 1 BChl molecules.

Bacterial Proteins↗

PubMed2005

A cross-sectional study of Krukenberg spindles and pigmented lens striae in a predominately black population: two highly associated clinical signs of anterior segment pigment dispersal.

PURPOSE: To investigate the relationship of Krukenberg spindles (KS) and pigmented lens striae (PLS), clinical signs related to iris pigment dispersal and possibly glaucoma. METHODS: During a 31-month period, 5 practitioners in an urban, primary eye care setting examined consecutive patients for KS and PLS. Multiple logistic regression was used to evaluate relationships among KS, PLS, and other variables. RESULTS: Krukenberg spindles were present in 65 patients (52 females), comprised of 57 of 2647 (2.2%) blacks, 5 of 303 (1.7%) whites, 2 of 121 (1.7%) Hispanics, and 1 of 55 (1.8%) Asians. PLS were present in 64 subjects (56 females), comprised of 59 (2.2%) blacks, 3 (1.0%) whites, and 2 (3.6%) Asians. KS and PLS were coexistent in 27 subjects. Mean age +/- SD (range) of the KS and PLS subjects was 63.1 +/- 15.0 years (24-88 years) and 67.0 +/- 10.4 years (33-88 years), respectively. Mean refractive error +/- SD (range) of KS and PLS right eyes was +0.55 +/- 2.32D (-6.50 to +5.50D) and +1.34 +/- 2.18D (-6.50 to +7.25D), respectively. Controlling for other variables, PLS were highly predictive (OR = 30.2, P < 0.0001) of KS, and KS were highly predictive (OR = 29.5, P < 0.0001) of PLS. Ignoring presence or absence of PLS, increasing age (in decades) (OR = 1.60, P < 0.0001) was strongly associated with KS. Ignoring presence or absence of KS, age (OR = 1.74, P < 0.0001), female gender (OR = 2.96, P = 0.009), and increasing hyperopic refractive error (OR = 1.30, P < 0.0001) were strongly associated with PLS. CONCLUSIONS: Krukenberg spindles and PLS were strongly associated in our patient population, and the likelihood of both increased with increasing age. Female gender and increasing hyperopic refractive error were highly significant predictors of PLS.

Adult↗

PubMed1983

Pigment analysis of chloroplast pigment-protein complexes in wheat.

Pigment-protein complexes separated from wheat (Triticum aestivum L. selection ND96-25 by two gel electrophoresis techniques were analyzed by high-performance liquid chromatography for chlorophylls and carotenoids. The two techniques are compared, and pigment analyses are given for the major reaction centers and light-harvesting complexes. Reaction centers contain mostly chlorophyll a, carotene, and lutein, whereas light-harvesting complexes contain chlorophyll a, chlorophyll b, lutein, and neoxanthin. The amounts of violaxanthin are variable.

Journal Article↗

PubMed2006

Pigmented mucoepidermoid carcinoma, a case report and review of the literature on melanin-pigmented salivary gland tumors.

This paper reports a well-differentiated mucoepidermoid carcinoma containing numerous melanocytes in the parenchyma in a middle-aged Japanese man. In addition to the characteristic histopathologic features of well-differentiated mucoepidermoid carcinoma, various-formed and -sized, pigmented cells were widely distributed in the parenchyma. Many of these were considered to be melanocytes containing melanin in their cytoplasm. Perusal of the English-language literature revealed only four cases of salivary gland tumors with parenchymal pigmentation: three mucoepidermoid carcinomas and one pleomorphic adenoma. The possible histogenesis of melanocytes in the salivary gland lesions is discussed, although no firm conclusion could be drawn.

Adult↗