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 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.     

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.     

Sur des pigments rouges de Levures

Summary This preliminary communication describes red, watersoluble pigments elaborated by an adeninedeficient mutant of a haploid strain of yeast (Saccharomyces cerevisi). Acid hydrolysis of these pigments liberates a number of amino acids. Some of the physical and chemical properties of these yeast pigments resemble those of the antipernicious anæmia factor (vitamin B₁₂ ¹) which contains one atom of cobalt and three atoms of phosphorus, with a molecular weight of 1,500. Our yeast pigments contain no cobalt but one or two atoms of phosphorus, with an approximate molecular weight of 2,000.A report on the biological activities of our pigments will appear in the near future.     

Alpha-fetoprotein in tumor-bearing mice assayed by particle agglutination inhibition

Summary Serum alpha-fetoprotein (AFP) in hepatoma BW7756-bearing mice was measured by a new particle agglutination inhibition test employing AFP adsorbed to charcoal particles. The AFP levels and tumor weights showed nearly parallel increases to means of 2633 g/ml and 5.2 g, respectively, 28 days after implantation. *** DIRECT SUPPORT *** A2025089 00011     

Weak neuronal accumulation of octopamine in dopaminergic neurons of the rabbit retina

Summary Dopaminergic retinal neurons become weakly radioactive after the injection of tritiated octopamine into the vitreous, but no other neurons do so. This indicates the absence of any effective mechanism for the accumulation of octopamine in rabbit retina. *** DIRECT SUPPORT *** A2025055 00008     

Nonspecific esterase activity in monkey thymus lymphocytes; study of distribution in lymphocyte subpopulation

Summary A subpopulation of monkey thymus lymphocytes was investigated by direct nonspecific esterase staining of Erosette forming lymphocytes. Thymus lymphocytes had high nonspecific esterase activity and E-rosette formation, but the level of their in vitro lectin responses was very low. *** DIRECT SUPPORT *** A2025117 00012     

Cholecystokinin-like peptides in avian brain and gut

Summary Extracts of turkey brain and jejunum contain a factor closely resembling the COOH-terminal octapeptide of porcine cholecystokinin (CCK). Turkey antral extracts contain factors distinguishable in immunochemical and gel filtration properties from the mammalian forms of gastrin and CCK. *** DIRECT SUPPORT *** A2025089 00007Acknowledgments. Skilled technical assistance was given by Elaine Clarke, Carol Higgins and Gavin Laing. Pure natural human G17 and G34 were generously provided by Prof. R.A. Gregory and Dr H.J. Tracy; pure natural porcine CCK33 was a generous gift from Prof. Viktor Mutt; the Squibb Institute for Medical Research kindly provided supplies of synthetic CCK8, and synthetic caerulein was a gift from Farmitalia Ltd.     

Verkürzte Methode zur Isolierung radiochemisch reinen Chlorophylls

Summary Radiochemically pure chlorophylla andb have been separated from barley by a rapid two-step purification procedure. It is based on chromatographic separation of pigments on polyamide columns and by paper chromatography.     

Die Farbstoffe der Blattläuse(Aphididae)

Summary Many dark-coloured species ofAphididae contain a colouring matter (protoaphin) of unusual structure in the haemolymph. After death of the insect this undergoes a remarkable series of changes by enzymic action yielding successively the pigments xanthoaphin, chrysoaphin and erythroaphin. Recent investigations leading to the complete structural elucidation of all these pigments is described.

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ViertePaul-Karrer-Vorlesung von Lord A. R. Todd F. R. S., gehalten an der Universität Zürich am 4, Juli 1962.     

Erythrocyte membrane lipid peroxidation in iron deficiency anemia

Summary Erythrocytes from normal subjects and from cases of iron deficiency anemia were exposed to hydrogen peroxide and the extent of membrane lipid peroxidation studied. Significantly less peroxidation was observed in intact anemic erythrocytes compared to normal. However, when isolated membrane lipids were subjected to peroxidation, there was no significant difference between the two groups. It is unlikely that lipid peroxidation per se plays a major role in the reported decrease in red cell life-span in iron deficiency. *** DIRECT SUPPORT *** A2025146 00003     

A new type of mutant ofEuglena which produces permanently bleached progeny by darkness

Summary A new type of mutant ofEuglena gracilis strain Z was isolated. In the light-grown culture, it contains 5–20% of bleached cells which have irreversibly lost the ability of chloroplast formation. When once grown in the dark, differing from the case with the wild type, it segregates only bleached cells, probably due to the inability of the replication of proplastids in darkness. Cell multiplication under the inhibition of chlorophyll synthesis or photosynthesis in the light also produces bleached cells.     

Are there cyclic variations in estradiol secretion in the non-pregnant rabbit?

Summary Plasma estradiol-17 (E2) concentration was measured in 5 adult non-pregnant rabbits each in 3 different seasons (January, April and September). Blood samples were taken from each rabbit every other day. There was a considerable variation in plasma E2 levels from one sampling day to another, irrespective of the season. The pattern of variation in E2 levels in individual rabbits tended to be cyclic and this cycle was roughly of the order of 8 days. There was no correlation between changes in E2 levels and those in the vaginal appearance. *** DIRECT SUPPORT *** A2025089 00013This study was supported by the Ford Foundation, and the Swedish Medical Research Council (project No. 4781).     

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.     

Elektronenmikroskopische Aufnahmen von Pollenschläuchen

Summary Electron micrographs were made of the cellulose part of the cell walls of pollen tubes ofPetunia hybrida, grown in selfed self-sterile plants and on agar plates. In sterile plants the tubes showed denser membranes but the orientation of the cellulose strands is the same as in cells germinated on agar.     

Neurosécrétion et régulation hydroélectrolytique chezArtemia salina

Summary The activity ofArtemia protocerebral median neurosecretory cells is stimulated when animals are grown in media whose tonicity is lower than that of sea weater. The substance liberated by these cells could regulate the tonicity of the internal medium.

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Neurosécrétion et régulation hydroélectrolytique chezArtemia salina

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Travail réalisé avec l'appui financier du FRFC (programme No 2.9010.75).     

Chemical communication in invertebrates

Conclusions In conclusion, olfactory pheromones are widespread in nature and control many fundamental aspects of an insect's life. Detailed behavioral observations in the field and laboratory indicate the great complexity of most pheromone communication systems. The preliminary electrophysiological experiments on single olfactory receptor neurons that we have described here, point toward the possibility of unraveling the basic physiological mechanisms underlying these behavioral complexities. This information is directly applicable to many problem areas in chemoreception and could provide a base for the rational use of pheromones in the control of insect pests. *** DIRECT SUPPORT *** A2025171 00003     

Production of insulin-like growth factor I (IGF-I) and IGF-binding proteins by rat intestinal stromal cells in vitro

To determine if intestinal stromal cells secrete diffusible factors such as insulin-like growth factors (IGFs) capable of regulating epithelial cell growth in vitro, stromal cells were isolated by enzymatic digestion of rat intestine. Incorporation of [³H]thymidine into DNA and [¹⁴C]leucine into protein of IEC-6 cells, a model intestinal epithelial cell line, was significantly increased (two- to threefold) when the IEC-6 cells were co-cultured with stromal cells, relative to IEC-6 cells grown alone. Medium conditioned by stromal cells stimulated DNA synthesis of IEC-6 cells in a dose-dependent manner. Analysis of the conditioned medium revealed that intestinal stromal cells secreted IGF-I, but little IGF-II, in addition to an M _r 32,000 IGF-binding protein (IGFBP-2) and an IGFBP having M _r∼ 24,000. We conclude that rat intestinal stromal cells secrete one or more diffusible factors, which may include IGF-I and IGFBPs, capable of stimulating proliferation of IEC-6 cells in vitro. Received 25 August 1997; received after revision 7 November 1997; accepted 20 November 1997