New violet 3,3′-bipyridyl pigment purified from deep-sea microorganism <Emphasis Type="Italic">Shewanella violacea</Emphasis> DSS12

We have purified a new violet pigment derived from Shewanella violacea DSS12 to determine its chemical structure. The pigment colored blue in tetrahydrofuran (THF) or chloroform and showed a broad absorption spectrum from 500 to 700 nm. X-ray diffraction analysis of single crystals showed that the chemical structure of this pigment was 5,5′-didodecylamino-4,4′-dihydroxy-3,3′-diazodiphenoquinone-(2,2′), containing the same chromophore as an indigoidine known as microbial blue pigment. The violet color of this pigment was due to hypsochromic shift (blue shift) caused by the side-by-side orientation of this pigment molecule, revealed by X-ray structural analyses of a single crystal. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Production of antibacterial violet pigment by psychrotropic bacterium RT102 strain

The antibacterial action of violet pigment, a mixture of violacein and deoxyviolacein, isolated from phychrotrophic bacterium RT102 strain was examined, and the operational conditions for the effective production of violet pigment were studied. The antibacterial activity of the violet pigment was confirmed for several bacteria such asBacillus licheniformis, Bacillus subtilis, Bacillus megaterium, Staphylococcus aureus, andPseudomonas aeruginosa, and the high concentration of violet pigment, above about 15 mg/L, caused not only growth inhibition but also death of cells. The growth properties of RT102 strain were clarified under various incubation conditions such as pH, temperature, and dissolved oxygen concentration. The maximum violet pigment concentration,i.e. 3.7 g/L, and the maximum productivity of violet pigment,i.e. 0.12 g L⁻¹h⁻¹, were obtained in a batch culture of pH 6, 20°C, and 1 mg/L of dissolved oxygen concentration.     

A Pigment-producing Spoilage Bacterium Responsible for Violet Discoloration of Refrigerated Market Milk and Cream

A psychrophilic strain of bacteria identified as Chromobacterium lividum was established as the causative agent of an outbreak of violet discoloration in refrigerated, pasteurized retail milk and cream.

The organism was rod-shaped, gram-negative, and produced viscid colonies with abundant violet pigment on Tryptone glucose yeast extract agar. Growth was abundant at 4 C but none occurred at 37 C. Growth in milk was characterized by a dark violet ring at the surface after a few days, and the deep violet color gradually extended through the product in older cultures. Some proteolysis occurred. The pigment appeared to be similar to that of other known species of Chromobacterium and assisted in identification of the genus of the causative organism.

The isolated strain of C. lividum was destroyed by exposure to 56 C for 5 min which suggested postpasteurization contamination as the source of the spoilage organism in commercial milk and cream.

     

Isolation of a blue-violet pigment from the flowers ofPlatycodon grandiflorum

A blue violet pigment was isolated in a crystalline state from the flowers ofPlatycodon grandiflorum A. DC. by the use of neutral solvents. The absorption spectrum of this pigment in buffer solution (pH 4.5) was almost identical with that of an intact tissue. The essential component of this pigment is platyconin, i.e., delphinidin 3-dicaffeoylrutinosido-5-glucoside.     

A novel amino acid substitution is responsible for spectral tuning in a rodent violet-sensitive visual pigment

Cone short-wave (SWS1) visual pigments can be divided into two categories that correlate with spectral sensitivity, violet sensitive above 390 nm and ultraviolet sensitive below that wavelength. The evolution and mechanism of spectral tuning of SWS1 opsins are proving more complex than those of other opsin classes. Violet-sensitive pigments probably evolved from an ancestral ultraviolet-sensitive opsin, although in birds ultraviolet sensitivity has re-evolved from violet-sensitive pigments. In certain mammals, a single substitution involving the gain of a polar residue can switch sensitivity from ultraviolet to violet sensitivity, but where such a change is not involved, several substitutions may be required to effect the switch. The guinea pig, Cavia porcellus, is a hystricognathous rodent, a distinct suborder from the Sciurognathi, such as rats and mice. It has been shown by microspectrophotometry to have two cone visual pigments at 530 and 400 nm. We have ascertained the sequence of the short-wave pigment and confirmed its violet sensitivity by expression and reconstitution of the pigment in vitro. Moreover, we have shown by site-directed mutagenesis that a single residue is responsible for wavelength tuning of spectral sensitivity, a Val86Phe causing a 60 nm short-wave shift into the ultraviolet and a Val86Tyr substitution shifting the pigment 8 nm long wave. The convergent evolution of this mammalian VS pigment provides insight into the mechanism of tuning between the violet and UV.     

The effect of the spectral composition of light on the growth,pigments, and photosynthetic rate of unicellular marine algae

Methods are given for obtaining spectral regimes related to algal absorption regions (red, green, violet) and to coastal, underwater light. Amphidinium and Biddulphia maintained for several months in these regimes have the same structure as when maintained in white light except Biddulphia in the red regime, in which there was breakdown in cytoplasmic structure, preponderance of large cells, and slower growth. Electron microscopy showed that the average number of thylakoid bands increased from 6.0 in white to 7.6 in red and appeared teased. Amphidinium did not show a gross morphological change but slower growth, crimping of bands, and increase in band number from 5.1 to 6.7 were observed. On the basis that increase in number and loss in compactness indicate stress, the stress effect of the regimes decreased from red, to green, to underwater, to white, and finally to violet.Algae grown in white light had their highest photosynthetic rate in the violet regime, then underwater, red, white, and green. When grown in any of the coloured regimes, the rate in violet was again highest. Changes in assimilation number for the different regimes compared with white light fell into three classes. First, both algae showed no change in green; there was also no pigment change with Amphidinium but a decrease with Biddulphia. Secondly, Amphidinium in red or underwater, and Biddulphia in red (before cytoplasmic breakdown) decreased their assimilaton number; this was accompanied by an increase in pigment, suggesting that the decreased usage of pigment in photosynthesis was due to increase in availability. Thirdly, Amphidinium in violet, and Biddulphia in underwater increased their assimilation number; this was accompanied by a decrease in pigments, suggesting that there was increased usage because of decreased availability, and that the pigment changes caused those in assimilation number.     

Effects of anthocyanin and carotenoid combinations on foliage and immature fruit color of Capsicum annuum L

Shades ranging from violet to black pigmentation in pepper (Capsicum annuum L.) are attributed to anthocyanin accumulation. High-performance liquid chromatography and mass spectrometry analysis of violet and black fruit tissue identified a single anthocyanin that was determined to be delphinidin-3-p-coumaroyl-rutinoside-5-glucoside. Leaf tissue of a black-pigmented foliage genotype contained the same anthocyanin found in fruit but at a considerably higher concentration in comparison to violet and black fruit tissue. Fruit chlorophyll concentration was approximately 14-fold higher in black fruit in comparison to violet fruit that contained relatively little chlorophyll. Beta-carotene, lutein, violaxanthin, and neoxanthin carotenoid concentrations in black fruit were also significantly greater in comparison to violet fruit. High concentrations of delphinidin in combination with chlorophyll and accessory carotenoid pigments produced the characteristic black pigmentation observed in fruits and leaves of selected genotypes. Anthocyanins were accumulated in the outer mesocarp of violet and black fruit and in the palisade and mesophyll cells of black leaves. Consistent with chlorophyll content of respective genotypes, chloroplast density was greater in cells of black fruits. Utilizing Capsicum pigment variants, we determine the biochemical factors responsible for violet versus black-pigmented pepper tissue in the context of described pepper color genes.     

Genetic basis of spectral tuning in the violet-sensitive visual pigment of African clawed frog, Xenopus laevis

Ultraviolet (UV) and violet vision in vertebrates is mediated by UV and violet visual pigments that absorb light maximally (lambdamax) at approximately 360 and 390-440 nm, respectively. So far, a total of 11 amino acid sites only in transmembrane (TM) helices I-III are known to be involved in the functional differentiation of these short wavelength-sensitive type 1 (SWS1) pigments. Here, we have constructed chimeric pigments between the violet pigment of African clawed frog (Xenopus laevis) and its ancestral UV pigment. The results show that not only are the absorption spectra of these pigments modulated strongly by amino acids in TM I-VII, but also, for unknown reasons, the overall effect of amino acid changes in TM IV-VII on the lambdamax-shift is abolished. The spectral tuning of the contemporary frog pigment is explained by amino acid replacements F86M, V91I, T93P, V109A, E113D, L116V, and S118T, in which V91I and V109A are previously unknown, increasing the total number of critical amino acid sites that are involved in the spectral tuning of SWS1 pigments in vertebrates to 13.     

Integumental reddish-violet coloration owing to novel dichromatic chromatophores in the teleost fish, Pseudochromis diadema

In the reddish-violet parts of the skin of the diadema pseudochromis Pseudochromis diadema, we found novel dichromatic chromatophores with a reddish pigment and reflecting platelets. We named these novel cells 'erythro-iridophores'. In standard physiological solution, erythro-iridophores displayed two hues, red and dark violet when viewed with an optical microscope under ordinary transmission light and epi-illumination optics, respectively. Under transmission electron microscopy, however, we observed no typical red chromatosomes, i.e., erythrosomes, in the cytoplasm. High-performance thin-layer chromatography (HPTLC) analysis of the pigment eluted from the erythro-iridophores indicated that carotenoid is the main pigment generating the reddish color. Furthermore, when the irrigating medium was a K(+)-rich saline solution, the color reflected from the erythro-iridophores changed from dark violet to sky blue, but the red coloration remained. The motile activities of the erythro-iridophores may participate in the changes in the reddish-violet shades of the pseudochromis fish.     

Deoxyribonucleic acid base composition and taxonomy of violet-pigmented cocci

The content of guanine and cytosine in DNA of the violet-pigmented micrococci designated asStaphylococcus flavocyaneus andMicrococcus flavocyaneus varies within the range of 70.8 – 72.0%. These species have similar deoxyribonucleic acid base compositions and do not differ physiologically and morphologically: they both produce yellow and violet pigments, hydrolyse gelatin and casein, reduce nitrates and do not form lipase. Therefore we consider them in accordance with Kocur and Martinec (1962, 1963) identical. They do not, however, seem to be identical withMicrococcus luteus (Schroeter, 1872) Cohn 1872 because the content of guanine and cytosine in DNA of the neotype culture of this species was found to be 66.3%.Micrococcus luteus differs from the violet pigmented micrococci also physiologically. It does not produce violet pigment, does not hydrolyse gelatin and casein and does not produce urease. For the violet pigmented strainMicrococcus cyaneus the use of the original designation is recommended:Micrococcus cyaneus (Schroeter) Cohn 1872, as it differs from the other violet cocci not only physiologically — it does not produce yellow pigment, oxidises mannitol, dulcitol and sorbitol, produces lipase and does not hydrolyse casein — but also in its DNA base composition.     

Spectral tuning and evolution of primate short-wavelength-sensitive visual pigments

The peak sensitivities (λ(max)) of the short-wavelength-sensitive-1 (SWS1) pigments in mammals range from the ultraviolet (UV) (360-400 nm) to the violet (400-450 nm) regions of the spectrum. In most cases, a UV or violet peak is determined by the residue present at site 86, with Phe conferring UV sensitivity (UVS) and either Ser, Tyr or Val causing a shift to violet wavelengths. In primates, however, the tuning mechanism of violet-sensitive (VS) pigments would appear to differ. In this study, we examine the tuning mechanisms of prosimian SWS1 pigments. One species, the aye-aye, possesses a pigment with Phe86 but in vitro spectral analysis reveals a VS rather than a UVS pigment. Other residues (Cys, Ser and Val) at site 86 in prosimians also gave VS pigments. Substitution at site 86 is not, therefore, the primary mechanism for the tuning of VS pigments in primates, and phylogenetic analysis indicates that substitutions at site 86 have occurred at least five times in primate evolution. The sole potential tuning site that is conserved in all primate VS pigments is Pro93, which when substituted by Thr (as found in mammalian UVS pigments) in the aye-aye pigment shifted the peak absorbance into the UV region with a λ(max) value at 371 nm. We, therefore, conclude that the tuning of VS pigments in primates depends on Pro93, not Tyr86 as in other mammals. However, it remains uncertain whether the initial event that gave rise to the VS pigment in the ancestral primate was achieved by a Thr93Pro or a Phe86Tyr substitution.     

Responses of anthocyanin-producing and non-producing cells of Glehnia littoralis to radical generators.

The responses of anthocyanin-producing (violet) and non-producing (white) cells of Glehnia littoralis to radical generators were compared. Cell growth, anthocyanin content, phenylalanine ammonia-lyase (PAL) activity and furanocoumarin production were determined after treatment with H(2)O(2), 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH), X-ray and yeast extract, independently. AAPH and H(2)O(2) repressed the growth of both violet and white cells, but violet cells grew better than white cells. On the other hand, the anthocyanin content in violet cells decreased. Neither X-ray nor yeast extract affected cell growth or pigment production. Treatment with H(2)O(2), yeast extract, and X-ray, but not AAPH, induced PAL activity and furanocoumarin production in white cell cultures, whereas violet cell cultures did not produce furanocoumarin following any of the treatment employed.     

Anthocyanins, colour and antioxidant properties of eggplant (Solanum melongena L.) and violet pepper (Capsicum annuum L.) peel extracts

Acetone extracts from eggplant (Solanum melongena L.) and violet pepper (Capsicum annuum L.) peels both belonging to the Solanaceae plant family were characterized with respect to their anthocyanin profiles, colour qualities and antioxidant capacities. According to HPLC-DAD-MS3 analyses the major anthocyanin in eggplant was delphinidin-3-rutinoside, while the predominant pigment in violet pepper was assigned to delphinidin-3-trans-coumaroylrutinoside-5-glucoside. Since virtually all anthocyanins were delphinidin-based, the effect of acylation and glycosylation patterns on colour stability and antioxidant capacity could be assessed. Application of two in vitro-assays for antioxidant capacity assessment revealed that eggplant generally exhibited higher values compared to violet pepper which was ascribed to 3,5-diglycosylated structures predominating in the latter. The higher extent of acylation in violet pepper was reflected by a more purplish colour shade of the extracts, but did not translate into a higher stability against fading which again was attributed to additional glycosyl substitution at C5. These findings support the relevance of structure-related activities of anthocyanins both for understanding food colour and their particular nutritional value.     

Selection of the medium for the simultaneous synthesis of an antibiotic, protease and pigment by a Nocardia fructiferi culture

Using method of mathematical planning of experiment the culture medium ensuring the simultaneous intensive production of ristomycin, protease and violet pigment by Nocardia fructiferi has been worked out.     

E113 is required for the efficient photoisomerization of the unprotonated chromophore in a UV-absorbing visual pigment

Protonation of the retinal Schiff base chromophore is responsible for the absorption of visible light and is stabilized by the counterion residue E113 in vertebrate visual pigments. However, this residue is also conserved in vertebrate UV-absorbing visual pigments (UV pigments) which have an unprotonated Schiff base chromophore. To elucidate the role played by this residue in the photoisomerization of the unprotonated chromophore in UV pigments, we measured the quantum yield of the E113Q mutant of the mouse UV cone pigment (mouse UV). The quantum yield of the mutant was much lower than that of the wild type, indicating that E113 is required for the efficient photoisomerization of the unprotonated chromophore in mouse UV. Introduction of the E113Q mutation into the chicken violet cone pigment (chicken violet), which has a protonated chromophore, caused deprotonation of the chromophore and a reduction in the quantum yield. On the other hand, the S90C mutation in chicken violet, which deprotonated the chromophore with E113 remaining intact, did not significantly affect the quantum yield. These results suggest that E113 facilitates photoisomerization in both UV-absorbing and visible light-absorbing visual pigments and provide a possible explanation for the complete conservation of E113 among vertebrate UV pigments.     

Photochemistry of the primary event in short-wavelength visual opsins at low temperature.

Two short-wavelength cone opsins, frog (Xenopus laevis) violet and mouse UV, were expressed in mammalian COS1 cells, purified in delipidated form, and studied using cryogenic UV-vis spectrophotometry. At room temperature, the X. laevis violet opsin has an absorption maximum at 426 nm when generated with 11-cis-retinal and an absorption maximum of 415 nm when generated with 9-cis-retinal. The frog short-wavelength opsin has two different batho intermediates, one stable at 30 K (lambda(max) approximately 446 nm) and the other at 70 K (lambda(max) approximately 475 nm). Chloride ions do not affect the absorption maximum of the violet opsin. At room temperature, mouse UV opsin has an absorption maximum of 357 nm, while at 70 K, the pigment exhibits a bathochromic shift to 403 nm with distinct vibronic structure and a strong secondary vibronic band at 380 nm. We have observed linear relationships when analyzing the energy difference between the initial and bathochromic intermediates and the normalized difference spectra of the batho-shifted intermediates of rod and cone opsins. We conclude that the binding sites of these pigments change from red to green to violet via systematic shifts in the position of the primary counterion relative to the protonated Schiff base. The mouse UV cone opsin does not fit this trend, and we conclude that wavelength selection in this pigment must operate via a different molecular mechanism. We discuss the possibility that the mouse UV chromophore is initially unprotonated.     

Trichromatic visual system in an insect and its sensitivity control by blue light

Summary The spectral sensitivity of the visual cells in the compound eye of the mothDeilephila elpenor was determined by electrophysiological mass recordings during exposure to monochromatic adapting light. Three types of receptors were identified. The receptors are maximally sensitive at about 350 nm (ultraviolet), 450 nm (violet), and 525 nm (green). The spectral sensitivity of the green receptors is identical to a nomogram for a rhodopsin with _max at 525 nm. The spectral sensitivity of the other two receptors rather well agrees with nomograms for corresponding rhodopsins. The recordings indicate that the green receptors occur in larger number than the other receptors. The ultra-violet and violet receptors probably occur in about equal number.The sensitivity after monochromatic adapting illumination varies with the wavelength of the adapting light, but is not proportional to the spectral sensitivity of the receptors. The sensitivity is proportional to the concentration of visual pigment at photoequilibrium. The equilibrium is determined by the absorbance coefficients of the visual pigment and its photoproduct at each wavelength. The concentration of the visual pigment, and thereby the sensitivity, is maximal at about 450 nm, and minimal at wavelengths exceeding about 570 nm.The light from a clear sky keeps the relative concentration of visual pigment in the green receptors, and the relative sensitivity, at about 0.62. The pigment concentration in the ultra-violet receptors is about 0.8 to 0.9, and that in the violet receptors probably about 0.6. At low ambient light intensities a chemical regeneration of the visual pigments may cause an increase in sensitivity. At higher intensities the concentrations of the visual pigments remain constant. Due to the constant pigment concentrations the input signals from the receptors to the central nervous system contain unequivocal information about variations in intensity and spectral distribution of the stimulating light.The work reported in this article was supported by the Swedish Medical Research Council (grant no B 73-04X-104-02B), by Karolinska Institutet, and by a grant (to G. Höglund) from Deutscher Akademischer Austauschdienst, and by the Deutsche Forschungsgemeinschaft, Schwerpunktsprogramm Rezeptorphysiologie HA 258-10, and SFB 114.     

A pentacyclic quinone diosindigo B from the heartwood of Diospyros melanoxylon

Diosindigo A, diosindigo B and biramentacéone have been isolated from heartwood of Diospyros melanoxylon. A violet pigment isolated from the same source has been shown to be a new pentacyclic quinone. Sunlight causes diosindigo B to change to the pentacyclic quinone and biramentacéone. The intense peaks at m/e 389 and 388 in the mass spectrum of diosindigo B are doublets which arise by fragmentation of both M⁺ and M⁺ + 2.     

Production of red pigment by submerged culture of Paecilomyces sinclairii

AIMS: From a survey of submerged culture of edible mushrooms, a high pigment-producing fungus Paecilomyces sinclairii was selected and its optimal culture conditions investigated. METHODS AND RESULTS: The optimal culture conditions for pigment production were as follows: inoculum age, 3 d; temperature, 25 degrees C; initial pH, 6.0; carbon source, 1.5% (w/v) soluble starch; nitrogen source, 1.5% (w/v) meat peptone. Although addition of 10 mmol l(-1) CaCl2 to the culture medium slightly increased pigment production, most of the bio-elements examined had no notable or detrimental effect on pigment production. CONCLUSIONS: Under the optimal conditions obtained in the flask culture tested, a ninefold increase in pigment production (4.4 g l(-1)) was achieved using a 5(-l) batch fermenter. Paecilomyces sinclairii secreted water-soluble red pigment into the culture medium. The pigment colour was strongly dependent on the pH of the solution: red at pH 3-4, violet at pH 5-9 and pink at pH 10-12. SIGNIFICANCE AND IMPACT OF THE STUDY: The high concentration of pigment (4.4 g l(-1)) produced by P. sinclairii demonstrates the possibility of commercial production of pigment by this strain, considering its relatively high production yield and light stability.     

Growth Inhibition of Various Organisms by a Violet Pigment,Nostocine A,Produced by Nostoc spongiaeforme

A freshwater filamentous cyanobacterium, Nostoc spongiaeforme TISTR 8169, produced and excreted a violet pigment, named nostocine A, in the culture medium. Nostocine A inhibited the growth of some typical strains of microorganisms, algae, cultured plants, and established animal cell lines.