Experimental studies of schistosomal pigment from Schistosoma japonicum.

The schistosomal and malarial pigments were distinguishable before and after extraction from the host liver. Presence of iron in both pigments was ascertained by the elemental X-ray analysis. Histochemically, however, schistosomal pigment was similar to that of malarial pigment.     

Vision in the ultraviolet

Sensitivity to ultraviolet light (UV) is achieved by photoreceptors in the eye that contain a class of visual pigments maximally sensitive to light at wavelengths <400 nm. It is widespread in the animal kingdom where it is used for mate choice, communication and foraging for food. UV sensitivity is not, however, a constant feature of the visual system, and in many vertebrate species, the UV-sensitive (UVS) pigment is replaced by a violet-sensitive (VS) pigment with maximal sensitivity between 410 and 435 nm. The role of protonation of the Schiff base-chromophore linkage and the mechanism for tuning of pigments into the UV is discussed in detail. Amino acid sequence analysis of vertebrate VS/UVS pigments indicates that the ancestral pigment was UVS, with loss of UV sensitivity occurring separately in mammals, amphibia and birds, and subsequently regained by a single amino acid substitution in certain bird species. In contrast, no loss of UV sensitivity has occurred in the UVS pigments of insects.     

Behavioral selection in crayfish correlates with movement of a screening pigment in the eye

Light induces two contrasting behavioral responses in crayfish: attraction at low intensities and withdrawal at high intensities. The aim of our experiments has been to study whether screening pigments of the eye influence the selection of attraction or withdrawal responses. During illumination, screening pigments mask photoreceptor cells, reducing the gain of the visual system. Comparison of the time and light-intensity functions of pigment migration and of attraction and withdrawal responses suggest that pigment migration might influence the selection as well as the latency of the response.     

Occurrence of soluble pigments in the genusBacillus

Résumé B. anthracis cultivé en bouillon dans certaines conditions précisées dans ce travail, produit un pigment rose sensible aux variations de pH.B. cereus produit de même, un pigment jaune-brun, fluorescent. Les pigments sont solubles et se retrouvent dans le filtrat. Quatre autres espèces deBacillus ne produisent pas de pigments dans les mêmes conditions. La production de pigments en bouillons de culture pourrait être employée comme un critère additionnel pour la classification des souchesBacillus.

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This investigation was supported by research grant E-1535 from the National Institutes of Health, U.S. Public Health Service.     

Quantification of melanin in hepatic and cardiac lipofuscin

Summary Melanin pigment in liver and heart tissue, obtained at autopsy from patients, was isolated and quantified. The quantity of melanin extracted was directly proportional to lipofuscin granule counts. Infrared and electron spin resonance spectrographs of the isolated pigments from liver and heart showed absorption characteristics identical to those of known melanins. The pigment was absent in fetal and neonatal life, increased in brown atrophy of the heart and liver, and diminished in livers with fatty metamorphosis.Supported by USPHS, grant NS 07542, the St. Vincent Hospital Research Foundation and the Dermatopathology Foundation.     

The comparative biology of neuromelanin and lipofuscin in the human brain

Neuromelanin and lipofuscin are two pigments produced within the human brain that, until recently, were considered inert cellular waste products of little interest to neuroscience. Recent research has increased our understanding of the nature and interactions of these pigments with their cellular environment and suggests that these pigments may, indeed, influence cellular function. The physical appearance and distribution of the pigments within the human brain differ, but both accumulate in the aging brain and the pigments share some structural features. Lipofuscin accumulation has been implicated in postmitotic cell aging, while neuromelanin is suggested to function as an iron-regulatory molecule with possible protective functions within the cells which produce this pigment. This review presents comparative aspects of the biology of neuromelanin and lipofuscin, as well as a discussion of their hypothesized functions in brain and their possible roles in aging and neurodegenerative disease.     

Pigment formation in sensory cells ofAplysia l

Summary The yellow-brown pigment present in the sensory cells ofAplysia limacina was studied using light and electron microscopy. The ultrastructure, the high carotenoid content and the presence in neurons for which a turnover process has been hypothesized, indicate that these pigments are cytosomes, organelles involved in the production of energy in anaerobiosis.This investigation was conducted at the Zoological Station of Naples.     

Phaeomelanic pigments from a human melanoma

Summary The pigments in melanomas from 2 patients were studied with regard to solubility and chemical composition. Melanoma pigment from a patient with red-blonde hair was alkali-soluble and contained 9 or 10% sulfur and was thus of phaeomelanic type. Melanoma pigment from a patient with red-brown hair was insoluble in 0.2N NaOH. Its sulfur content was 6%. This pigment was eumelanic with regard to solubility characteristics but the sulfur content was higher than previously observed for eumelanin.Supported by grants from the Swedish Cancer Society (No. 626-B75-04XA), the Swedish Medical Research Council (No. B76-04X-00056-12), and the Walter, Ellen, and Lennart Hesselman Foundation for Scientific Research. ProfessorProta was a visiting scientist of the Swedish Cancer Society (No. 626-B75-04U).     

Phénomènes chromatiques et rythme nycthéméral chezHippolyte varians Leach (crustacé décapode)

Summary Hippolyte varians passes through a daily colour-cycle, but a given pigment shows an opposite behaviour according to the chromatophore pattern. A significant variation in the state of concentration of pigments is observed in males and females.     

Anion sensitivity and spectral tuning of middle- and long-wavelength-sensitive (MWS/LWS) visual pigments

The long-wavelength-sensitive (LWS) opsins form one of four classes of vertebrate cone visual pigment and exhibit peak spectral sensitivities (λ(max)) that generally range from 525 to 560 nm for rhodopsin/vitamin-A(1) photopigments. Unique amongst the opsin classes, many LWS pigments show anion sensitivity through the interaction of chloride ions with a histidine residue at site 197 (H197) to give a long-wavelength spectral shift in peak sensitivity. Although it has been shown that amino acid substitutions at five sites (180, 197, 277, 285 and 308) are useful in predicting the λ(max) values of the LWS pigment class, some species, such as the elephant shark and most marine mammals, express LWS opsins that possess λ(max) values that are not consistent with this 'five-site' rule, indicating that other interactions may be involved. This study has taken advantage of the natural mutation at the chloride-binding site in the mouse LWS pigment. Through the use of a number of mutant pigments generated by site-directed mutagenesis, a new model has been formulated that takes into account the role of charge and steric properties of the side chains of residues at sites 197 and 308 in the function of the chloride-binding site in determining the peak sensitivity of LWS photopigments.     

Visual pigment: G-protein-coupled receptor for light signals

The visual pigment present in photoreceptor cells is a prototypical G-protein-coupled receptor (GPCR) that receives a light signal from the outer environment using a light-absorbing chromophore, 11-cis-retinal. Through cis-trans isomerization of the chromophore, light energy is transduced into chemical free energy, which is in turn utilized for conformational changes in the protein to activate the retinal G-protein. In combination with site-directed mutagenesis, various spectroscopic and biochemical studies identified functional residues responsible for chromophore binding, color regulation, intramolecular signal transduction and G-protein coupling. Extensive studies reveal that these residues are localized into specific domains of visual pigments, suggesting a highly manipulated molecular architecture in visual pigments. In addition to the recent findings on dysfunctional mutations in patients with retinitis pigmentosa or congenital night blindness, the mechanism of intramolecular signal transduction in visual pigments and their evolutionary relationship are discussed. Received 20 July 1998; received after revision 9 September 1998; accepted 23 September 1998     

Pigment distribution in cyanobacteria: An in vivo microspectroscopic investigation

Summary In vivo microspectroscopy represents an effective and reliable technique to study pigment composition and distribution. In contrast to traditional extractive techniques, it preserves the integrity of biological specimens, without modifying the nature of the pigments. The spectroscopic apparatus we used is very simple and consists of a common microscope equipped with a monochromator, a photomultiplier, and two pinhole diaphragms. Absorption spectra obtained by means of this apparatus on different species of cyanobacteria are presented.     

Anthocyanins inDioscorea alata L.

Résumé Trois arthocyanidines acylées ont été extraits de tubercules d'une variété deDioscorea alata L. des Antilles. Tous 3 sont des glycosides de la cyanidine: le pigment principal est la cyanidine-3-gentiobioside acylée d'acide ferrulique; les 2 autres pigments secondaires sont semblables aux cyanidine-3-glycosides acylées d'acide ferrulique.     

On partial and differential bleaching experiments with the visual pigments in a fresh water euryhaline teleost (Etroplus suratensis)

Summary Visual pigment was extracted from a fresh water toleost,Etroplus suratensis and the optical density measured over a range of 300–650 nm. The absorption spectrum indicates the _max at 550 nm and a small hump at 530 nm. Through partial bleaching at 630 nm, it was confirmed that the fish possesses a mixture of 2 visual pigments: the one with the _max at 550 nm predominating over the other.     

IgG deposits and Disse's space pathology in human schistosomal liver

Summary IgG deposits were identified in Disse's spaces of patients with advanced Symmers' fibrosis consequent to schistosomal infection.This work was supported by an A. T. P. (18-75-41) Inserm (France) and by the Conselho Nacional de Pesquisas (Brazil). —The Centre de documentation et d'information Franco-Egyptien et l'Ambassade de France en République d'Egypte are acknowledged for their valuable assistance.     

Renal handling of bilirubin photoderivatives

The renal handling of unconjugated bilirubin in the dark and during light exposure was analyzed using an isolated rat kidney preparation. The parameters tested were pigment disappearance from the perfusion medium, pigment uptake by tissue, and its renal clearance. The results indicated that despite the fact that pigment disappearance from the medium was similar for both forms of pigment, the extraction ratio was higher for irradiated pigment than for pigment in the dark. When renal clearance of pigment was plotted vs pigment uptake of tissue, the results indicated that irradiated pigment may be more efficiently removed by the kidney. In addition, data on the rate of secretion of p-aminohippurate suggested that both pigment forms shared a common site for secretion.     

Polyvinylchloride (PVC) particles implantation in mouse liver. A technique for experimental study of schistosome eggs-induced liver pathology.

An injection of suspended PVC particles in the caecal vein of mice induces a foreign-body portal granuloma reaction in the liver. Plastic casts of the portal system, after PVC particles implantation, show modifications in the portal bed and are compared with plastic casts obtained in mice infested by Schistosoma mansoni. This technique can be useful to study the cellular dynamics of the portal granuloma and can be a model for schistosomal eggs induced liver pathology.     

Polyvinylchloride (PVC) particles implantation in mouse liver. A technique for experimental study of schistosome eggs-induced liver pathology

Summary An injection of suspended PVC particles in the caecal vein of mice induces a foreign-body portal granuloma reaction in the liver. Plastic casts of the portal system, after PVC particles implantation, show modifications in the portal bed and are compared with plastic casts obtained in mice infested bySchistosoma mansoni. This technique can be useful to study the cellular dynamics of the portal granuloma and can be a model for schistosomal eggs induced liver pathology.This work was supported by an ATP (INSERM) 18.75.41 and a scholarship from the Société d'Hépatologie Expérimentale.     

Renal handling of bilirubin photoderivatives

Summary The renal handling of unconjugated bilirubin in the dark and during light exposure was analyzed using an isolated rat kidney preparation. The parameters tested were pigment disappearance from the perfusion medium, pigment uptake by tissue, and its renal clearance. The results indicated that despite the fact that pigment disappearance from the medium was similar for both forms of pigment, the extraction ratio was higher for irradiated pigment than for pigment in the dark. When renal clearance of pigment was plotted vs pigment uptake of tissue, the results indicated that irradiated pigment may be more efficiently removed by the kidney. In addition, data on the rate of secretion of p-aminohippurate suggested that both pigment forms shared a common site for secretion.13 August 1986Acknowledgments. This work was supported by grants from Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET), República Argentina. The valuable technical assistance of J. Pellegrino and E. Luque is gratefully acknowledged. We are also indebted to Dr S. Bravlavsky (Max-Planck Institut für Strahlenchemie, D-4330 Mülheim a. d. Ruhr, FRG) for stimulating discussion, and to Mr B. Leguizamón for secretarial assistance.