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PubMed2000

Effect of some antibiotics on pigmentation in Serratia marcescens.

Serratia marcescens is characterized by its ability to produce a red pigment called prodigiosin. It is well known that there are some substances affecting pigmentation in bacteria. Cefoxitin, erythromycin, tobramycin, co-trimoxazole, imipenem and nitrofurantoin were found to have an inhibitory effect on pigmentation in a S. marcescens strain isolated from urine. It was also shown that the LD50 dose determined by inoculation of eight-week-old BALB/c mice with serial dilutions of overnight cultures of pigmented and nonpigmented variants was lower (LD50 = 300 x 10(3.94)) in the nonpigmented variant than in the pigmented one (LD50 = 300 x 10(5.58)). In addition, the Sereny test showed that in contrast to the pigmented variant, the nonpigmented variant caused keratitis in guinea pig eye.

Animals↗
PubMed2002

The effect of dietary carotenoid access on sexual dichromatism and plumage pigment composition in the American goldfinch.

We investigated potential dietary and biochemical bases for carotenoid-based sexual dichromatism in American goldfinches (Carduelis tristis). Captive male and female finches were given access to the same type and amount of carotenoid pigments in the diet during their nuptial molt to assess differences in the degree to which the two sexes incorporated ingested pigments into their plumage. When birds were fed a uniform, plain-seed diet, or one that was supplemented with the red carotenoid canthaxanthin, we found that males grew more colorful plumage than females. HPLC analyses of feather pigments revealed that male finches incorporated a higher concentration of carotenoids into their pigmented feathers than females. Compared to females, males also deposited significantly more canary xanthophyll B into feathers when fed a plain-seed diet and a greater concentration and proportion of canthaxanthin when fed a carotenoid-supplemented diet. These results indicate that sex-specific expression of carotenoid pigmentation in American goldfinches may be affected by the means by which males and females physiologically utilize (e.g. absorb, transport, metabolize, deposit) carotenoid pigments available to them in the diet.

Animals↗
PubMed1999

A simple and rapid method for analyzing the Monascus pigment-mediated degradation of mutagenic 3-hydroxyamino-1-methyl-5H-pyrido[4,3-b]indole by in-capillary micellar electrokinetic chromatography.

A simple and rapid method is described for analyzing the Monascus pigment-mediated degradation of 3-hydroxyamino-1-methyl-5H-pyrido[4, 3-b]indole (Trp-P-2(NHOH)). We used the in-capillary micellar electrokinetic chromatography (MEKC). During the electrophoresis, the mutagen and the pigment, due to their different migration velocities, mix for a certain period of time to interact, and then they are separated and quantified. Using this technique, we were able to demonstrate that Trp-P-2(NHOH) is degraded by the pigment. The degradation was pigment-dose dependent, and because the pigment was recovered unchanged, it was deduced that the pigment acted catalytically for the degradation. The entire MEKC procedure takes 8 min.

Antimutagenic Agents↗
PubMed1992

Immunocytochemical reactivity of rod and cone visual pigments in the sturgeon retina.

Microspectrophotometry and immunocytochemistry with several antivisual pigment antibodies were used to study visual cells of the Siberian sturgeon, Acipenser baeri Brandt. The retina contained rods and three morphological types of cones: large cones with oil drops, small cones with oil drops, and cone-like cells without oil drops. Rods and cone-like drop-free cells were found to possess porphyropsin-549, while the large oil drop-bearing cones contained red-sensitive (P613), green-sensitive (P542), and blue-sensitive (P462) visual pigments. The immunocytochemical staining pattern with three antibodies to visual pigment proteins also revealed one visual pigment in rods and three visual pigments in cones. Rods were labeled with all three antibodies, while the majority of large cones (type I), presumably the red-sensitive ones, were negative with the polyclonal serum AO against bovine opsin. A less-frequently occurring large cone type (type II) was stained by all three antibodies including mAb COS-1 specific to middle-to-long-wave visual pigments in birds and mammals, and is thought to be green-sensitive. An even less-frequent large cone type (type III, probably the blue-sensitive one) did not bind COS-1. The small cones with oil droplets showed immunoreactivities similar to either type II or type III cones. The oil drop-free small photoreceptor exhibited a staining pattern identical with that of rods. These results indicate that the immunocytochemical approach can be used to reveal photoreceptor-specific neural connections in the sturgeon retina.

Animals↗
PubMedDate not supplied

Photoreceptors and visual pigments in the red-eared turtle, Trachemys scripta elegans.

Absorbance spectra of cone outer segments and oil droplets were recorded microspectrophotometrically in the retina of the red-eared turtle, Trachemys scripta elegans. There are four cone visual pigments, with lambda(max) = 617 nm (red sensitive), 515 nm (green sensitive), 458 nm (blue sensitive), and 372 nm (UV-sensitive). The red-sensitive pigment resides in single cones with red or orange oil droplets, and in both members of double cones. The principal member of the double cone contains an orange oil droplet, and the accessory member is droplet free. The green-sensitive pigment is situated in single cones with orange/dark yellow droplets. The blue-sensitive pigment is combined with the UV-absorbing oil droplet in single cones. The UV-sensitive pigment resides in single cones with clear oil droplets that exhibited virtually no absorbance down to 325 nm. Thus, seven types of cones can be identified based on their morphology, oil droplet color, and the visual pigment absorbance. At the moment, this is the most complex cone system described for vertebrates.

Animals↗
PubMedDate not supplied

Novel form of a single X-linked visual pigment gene in a unique dichromatic color-vision defect.

In normal trichromats, the long- (L) and middle-wavelength-sensitive (M) pigment genes are arranged in a head-to-tandem array on the X chromosome. Two amino acids at positions 277 and 285, encoded by exon 5 of the L and M genes, respectively, are essential for the spectral difference between L and M pigments whose spectral peaks are at approximately 560 and 530 nm. Intragenic or intergenic unequal crossing-over commonly occurs between the highly homologous L and M genes, resulting in red-green color vision deficiencies. The dichromacy is usually associated with a single L gene for deuteranopia or a single 5' L-M 3' hybrid gene with M-gene exon 5 for protanopia. We clinically diagnosed a total of 88 male dichromats using a Nagel model I anomaloscope, which included one unclassified subject in addition to 31 protanopes and 56 deuteranopes. The objective of this study was to characterize the phenotype of the subject and to determine the genotype of his X-linked pigment genes. The subject accepted not only any red-green mixture but also an extended yellow-scale range at each matching point (i.e. 20 to 32 scale units at the green primary and 3.5 to 6 scale units at the red primary). The slopes of regression lines were in the range of -0.34 to -0.23, while the mean slopes for the protanopes and deuteranopes were -0.38 and -0.01, respectively. Spectral sensitivity tests showed that the subject's curve was shifted between the protanope and deuteranope curves. Molecular analysis revealed a novel form of a single pigment gene with a unique arrangement of exon 5 (Y277 from the L gene and A285 from the M gene). The predicted lambdamax (541 to 546 nm) of the unique pigment was closer to the M than to the L pigment. Our outcome suggests that intragenic unequal crossing-over may have occurred between amino acid positions 279 and 283.

Adult↗
PubMed1991

Design, chemical synthesis, and expression of genes for the three human color vision pigments.

Color vision in humans is mediated by three pigments from retinal cone photoreceptor cells: blue, green, and red. We have designed and chemically synthesized genes for each of these three pigments. The genes were expressed in COS cells, reconstituted with 11-cis-retinal chromophore, and purified to homogeneity using an immunoaffinity procedure. To facilitate the immunoaffinity purification, each pigment was modified at the carboxy terminus to contain an additional eight amino acid epitope for a monoclonal antibody previously used to purify bovine rhodopsin. The spectra for the isolated pigments had maxima of 424, 530, and 560 nm, respectively, for the blue, green, and red pigments. These maxima are in excellent agreement with the maxima previously observed by microspectrophotometry of individual human cone cells. The spectra are the first to be obtained from isolated human color vision pigments. They confirm the original identification of the three color vision genes, which was based on genetic evidence [Nathans, J., Thomas, D., & Hogness, D.S. (1986) Science 232, 193].

Amino Acid Sequence↗
PubMed1990

14-Fluorobacteriorhodopsin and other fluorinated and 14-substituted analogues. An extra, unusually red-shifted pigment formed during dark adaptation.

Five vinyl-substituted fluororetinal analogues (8-F, 10-F, 12-F, 14-F, and 13,14-F2) were found to give bacteriorhodopsin analogues with properties similar to those of the parent system. Of these, only 14-fluororetinal was found to give an extra red-shifted BR analogue (lambda max less than or equal to 680 nm) in equilibrium with the normal 587-nm pigment. The 680-nm pigment was enriched upon irradiation. It rearranged to the 587-nm pigment at room temperature (delta E [symbol: see text] = 20.8 kcal/mol). Chromophore extraction experiments revealed the all-trans geometry for the 680-nm pigment. 14-Chlororetinal gave a similarly red-shifted pigment while 14-methylretinal did not. A scheme for dark adaptation of the 14-halogenated bacteriorhodopsins has been proposed in which the new red-shifted pigment was assigned the all-trans, 15-syn geometry.

Bacteriorhodopsins↗
PubMed1998

The cyanobacterium Spirulina platensis contains a long wavelength-absorbing pigment C738 (F76077K) at room temperature.

Spirulina platensis is a cyanobacterium which usually lives under high-light conditions. Nonetheless, it is thought to contain the most red-shifted antenna pigment of all known Chl a-containing phototrophic organisms, as shown by its 77 K fluorescence peaking at 760 nm. To exclude preparation artifacts and to exclude the possibility that long wavelength-absorbing pigments form only when the temperature is lowered to 77 K, we carried out experiments with whole cells at room temperature. The combined analysis of stationary absorption and fluorescence spectra as well as fluorescence induction and time-resolved fluorescence decays shows that the pigment responsible for the 77 K fluorescence at 760 nm (i) has the oscillator strength of approximately one Chl a molecule, (ii) absorbs maximally at 738 nm (), (iii) is present only in the antenna system of PS I, (iv) participates in light collection, and (v) does not entail a low photochemical quantum yield. Other, more abundant but less red-shifted Chl a antenna pigments lead to a significantly larger absorption cross section of the photosynthetic unit of PS I above 700 nm compared to units that would not possess these long wavelength-absorbing pigments. These results support the hypothesis that the physiological role of long wavelength-absorbing pigments is to increase the absorption cross section at wavelengths of >700 nm when in densely populated mats the spectrally filtered light is relatively more intense at these wavelengths [Trissl, H.-W. (1993) Photosynth. Res. 35, 247-263].

Chlorophyll↗
PubMed1997

A comparison of phenobarbital and codeine incorporation into pigmented and nonpigmented rat hair.

Drugs and endogenous compounds circulating in the blood may ultimately become incorporated into a growing hair shaft. Hair analysis for drugs of abuse is a growing field in the area of forensic and clinical toxicology. However, the underlying principles that govern drug incorporation into hair are not known. In this study, we examined the incorporation of a weak acid, phenobarbital, and a weak base, codeine, into Sprague-Dawley (SD) rat hair. Codeine or phenobarbital was administered to male SD rats at 40 mg/kg/day for 5 days by intraperitoneal (ip) injection. Hair was collected from the back 14 days after beginning the 5-day dosing protocol and analyzed by gas chromatography/mass spectrometry (GC/MS) for codeine and phenobarbital. The time-courses of phenobarbital and codeine in plasma were also obtained after a single ip injection (40 mg/kg). Concentrations of codeine and phenobarbital in SD hair samples were 0.98 +/- 0.10 and 17.01 +/- 1.40 ng/mg hair. respectively. The areas under the curve (AUC) of plasma concentration versus time for codeine and phenobarbital were 1.58 and 414.50 micrograms h/microL, respectively. Notwithstanding the greater phenobarbital concentrations in hair, when plasma concentrations were considered, codeine was apparently incorporated to a 15-fold greater extent than phenobarbital. Because hair pigmentation may be important in drug incorporation, the incorporation of these two drugs was also studied in Long-Evans (LE; produces both black and white hair on the same animal) rats after 40 mg/kg/day of ip drug administration for 5 days. Hair was collected at the same time as the previous experiment. Concentrations of codeine in hair were 44-times greater in pigmented than nonpigmented hair from the same animals. In contrast, hair concentrations of phenobarbital were identical in both pigmented and nonpigmented hair. These data suggest that hair pigmentation greatly affects weak base incorporation but not weak acid incorporation into hair. Because hair concentrations of phenobarbital are not affected by pigmentation, phenobarbital may be an ideal drug to separate out factors other than pigmentation involved in incorporation of drugs into hair.

Animals↗
PubMed2004

Qualitative and quantitative composition of pigments in Phaeodactylum tricornutum (Bacillariophyceae) stressed by iron.

The effect of Fe(III) deficiency on qualitative and quantitative changes in pigment composition in Phaeodactylum tricornutum Bohlin was demonstrated by HPLC and AAS. Maximum content of pigments showed the diatom cells incubated at the optimum iron concentration, i.e., 10 microM. The contents of chlorophyll a, chlorophyll c1 + c2, fucoxanthin, diadinoxanthin and beta,beta-carotene were 109.99, 20.16, 40.39, 1.29 and 1.48 fg per cell, respectively. The results obtained showed that Fe(III) affected qualitative and quantitative pigment composition in P. tricornutum. The content of individual pigments, proportions between accompanying pigments and their ratios to chlorophyll a were important indicators of phytoplankton response to iron stress. The strong reduction in beta,beta-carotene content, several times (2-5) increase in diadinoxanthin level as compared to beta,beta-carotene, and high amount of diadinoxanthin in relation to chlorophyll a were observed in algae growing at very low Fe(III) concentrations, 0.001 and 0.01 microM. The data suggested that phytoplankton pigments could be a potential physiological marker.

Chlorophyll↗
PubMed2001

Oral melanin pigmentation related to smoking in a Turkish population.

OBJECTIVE: Besides genetic factors, tobacco smoking has been found to be the major cause of oral melanin pigmentation. The purpose of the present study was to evaluate the frequency of oral melanin pigmentation in a Turkish population and to present its correlation with clinical parameters relevant to periodontal status in current smokers, non-smokers, former smokers. METHOD: A sample of 496 patients was randomly selected. The subjects were interviewed regarding their smoking habits. They were clinically examined by a single examiner for the presence of oral melanin pigmentation in different oral mucosal regions. The same examiner recorded the clinical parameters including GI (gingival index), PI (plaque index), BOP (bleeding on probing), PD (probing depth) and GR (gingival recession). Examiner 2 completed a questionnaire concerning skin color and smoking habits. RESULTS: In the study group, 41% were current smokers, 46% nonsmokers and 13% former smokers. The frequencies of pigmented areas were significantly higher in current smokers than in those without any smoking habits. The clinical parameters revealed similar findings for all groups. Low GI and BOP values were observed for current smokers when compared with non-smokers and former smokers, respectively. GI values were significantly associated with the pigmentations in gingiva. CONCLUSIONS: The results of our study show that smokers in a Turkish population had significantly more pigmented oral surfaces than nonsmokers.

Adult↗
PubMed2000

The inbred mouse in pigmentation research: significance of a congenic developmental system.

Pigment mutations in inbred mice have been important to many new scientific developments over the past century. Inbred mice are essentially genetically alike because of 10-20 generations or more of sibling mating or the equivalent. Mice of the same inbred strain that differ at only one locus can be used to evaluate the phenotypic effects of that one locus without complication of variation at other loci. Similarly, genic interactions among the functions of two or more loci are evaluated by comparing them in all combinations against a uniform genetic background. The next logical step in describing the pigment system will occur when all pigment cell biologists who use mice (cells, tissues, DNA, RNA) make certain that their mice are congenic with C57BL/6J. As a result, the work of all investigators will be genetically comparable. Their work will also be comparable to those investigating other organ systems, because NIH has chosen C57BL/6J as one of its two standard strains. As a result of this standardization, interactions among the different gene loci that function in the pigment system will become more readily evident and the community of pigment cell biologists using congenic mice will be able to analyze the functional interplay of loci that regulate the entire pigment system in the same way that earlier researchers analyzed one mutant allele, or the interactions of two mutant loci.

Alleles↗
PubMed2001

Production of melanocyte-specific antibodies to human melanosomal proteins: expression patterns in normal human skin and in cutaneous pigmented lesions.

Multiple factors affect skin pigmentation, including those that regulate melanocyte and/or keratinocyte function. Such factors, particularly those that operate at the level of the melanosome, are relatively well characterized in mice, but the expression and function of structural and enzymatic proteins in melanocytes in human skin are not as well known. Some years ago, we generated peptide-specific antibodies to murine melanosomal proteins that proved to be instrumental in elucidating melanocyte development and differentiation in mice, but cross-reactivity of those antibodies with the corresponding human proteins often was weak or absent. In an effort to characterize the roles of melanosomal proteins in human skin pigmentation, and to understand the underlying mechanism(s) of abnormal skin pigmentation, we have now generated polyclonal antibodies against the human melanocyte-specific markers, tyrosinase, tyrosinase-related protein (TYRP1), Dopachrome tautomerase (DCT) and Pmel17 (SILV, also known as GP100). We used these antibodies to determine the distribution and function of melanosomal proteins in normal human skin (adult and newborn) and in various cutaneous pigmented lesions, such as intradermal nevi, lentigo simplex, solar lentigines and malignant melanomas. We also examined cytokeratin expression in these same samples to assess keratinocyte distribution and function. Immunohistochemical staining reveals distinct patterns of melanocyte distribution and function in normal skin and in various types of cutaneous pigmented lesions. Those differences in the expression patterns of melanocyte markers provide important clues to the roles of melanocytes in normal and in disrupted skin pigmentation.

Adult↗
PubMed2002

Spleen and liver pigmented macrophages of Rana esculenta L. A new melanogenic system?

The present study reports the results of a morpho-functional analysis of spleen pigmented cells from Rana esculenta L. and comparison with liver melanin-synthesizing cells, belonging to the macrophage cell lineage. Cytological and cytochemical analyses show that parenchymal pigmented cells of the spleen, like those of the liver, are positive to peroxidase and lipase reactions and have phagocytic properties. The observation of premelanosomes in various stages of differentiation, together with the demonstration of dopa oxidase activity in the melanosome proteins, indicate that spleen pigmented macrophages have endogenous melanogenic ability as do liver pigmented macrophages. Attempts to demonstrate tyrosinehydroxylase activity in melanosome protein extracts from frog spleen and liver, using the same protocol as for mammalian tyrosinases, gave negative results. As regards the dopa oxidase activity revealed, some of its properties differ from the typical behaviour observed for tyrosinases from different sources. Peroxidase activity is shown in spleen and liver melanosome proteins with p-phenylenediamine-pyrocatechol (PPD-PC), and not with typical peroxidase substrates. Suitable inhibition tests revealed that dopa oxidase and peroxidase activities might be supported by two different proteins. Liver melanosome extracts display a very strong laccase (dimethoxyphenoloxidase) activity but spleen extracts do not. Differences observed in the enzymatic properties of the spleen and liver melanosomes suggest that pigmented macrophages may undergo tissue-specific differentiation. These preliminary data show that the melanin pathway of pigmented macrophages is different from that of melanocytes and may pave the way to identification of a new melanogenic pathway in vertebrates.

Animals↗
PubMed2002

Expression of Cre recombinase in pigment cells.

Conditional gene targeting using the Cre/loxP system enables specific deletion of a gene in a tissue of interest. For application of Cre-mediated recombination in pigment cells, Cre expression has to be targeted to pigment cells in transgenic mice. So far, no pigment cell-specific Cre transgenic line has been reported and we present and discuss our first results on use of Cre recombinase in pigment cells. A construct was generated where Cre recombinase is controlled by the promoter of the mouse dopachrome tautomerase (Dct) gene. The construct was functionally tested in vitro and introduced into mice. Following breeding to two reporter mouse strains, we detected Cre recombinase activity in telencephalon, melanoblasts, and retinal pigment epithelium (RPE). Our data demonstrate the feasibility of pigment cell-specific Cre/loxP-mediated recombination.

Animals↗
PubMed2001

The phagocytosis of rod outer segments is inhibited by selected drugs in retinal pigment epithelial cell cultures.

The effects of tamoxifen, toremifene and chloroquine on the phagocytosis of rod outer segments by retinal pigment epithelium were evaluated in human retinal pigment epithelial cell line D407 and pig retinal pigment epithelial cell culture. Retinal pigment epithelial cells were exposed to different concentrations of tamoxifen (1-20 microM), toremifene (1-20 microM) and chloroquine (1-1000 microM), and challenged with FITC-labeled rod outer segments for 24 hr. The phagocytized (bound and ingested) rod outer segments were measured fluorometrically, and the effect of the drugs on the phagocytosis was determined. The cytotoxicity of the drugs was evaluated by measuring their effects on mitochondrial enzyme activities (WST-1-test). The results showed that the test compounds inhibited the phagocytosis of rod outer segments in both D407 and pig retinal pigment epithelial cells. The phagocytic activity was more sensitive to tamoxifen (EC(50) 7.2 microM for D407 cells and 3.6 microM for pig retinal pigment epithelial cells) and toremifene (EC(50) 6.2 microM and 3.1 microM respectively) than to chloroquine (EC(50) 77.2 microM for D407 cells). The inhibition of rod outer segment phagocytosis in both cell cultures started at lower dose levels of test compounds than the cytotoxicity indicated by the WST-1-test. The experiments were carried out both in serum-free medium and serum-containing medium. Serum seemed to be a critical factor in the medium and caused difficulties in the interpretation of the results.

Animals↗
PubMed2001

The polarity of the retinal pigment epithelium.

The diversity of epithelia in the body permits a multitude of organ-specific functions. One of the foremost examples of this is the retinal pigment epithelium. Located between the photoreceptors of the retina and their principal blood supply, the choriocapillaris, the retinal pigment epithelium is critical for the survival and function of retinal photoreceptors. To serve this purpose, the retinal pigment epithelium cell has adapted the classic Golgi-to-cell-surface targeting pathways first described in such prototypic epithelial cell models as the Madin-Darby canine kidney cell, to arrive at a unique distribution of membrane and secreted proteins. More recent data suggest that the retinal pigment epithelium also takes advantage of its inherent asymmetry to augment the classical pathways of Golgi-to-cell-surface traffic. As retinal pigment epithelium transplants and gene therapy represent potential cures for retinal degenerative diseases, understanding the basis of the unique polarity properties of retinal pigment epithelium cells will be a critical issue for the development of future therapies.

Animals↗