Pigmentation and sporulation in selected Myxomycetes

Chemical, chromatographic and spectrometric methods are used to characterize plasmodial pigments and determine relationships between pigmentation and sporulation in selected Myxomycetes. In Physarum gyrosum (white) a single pigment is identified and characterized as a flavone. Physarum polycephalum (yellow) and Didymium iridis (brown) contain four and six components, respectively, in their plasmodial pigments which test negatively for flavones but show the presence of some type of phenolic compound. No detectable component is identified in the white plasmodium of Didymium squamulosum which proved to be independent of light for fruiting. The absorption spectra of all species that were light sensitive for fruiting showed common peaks in the 300–400-mμ region, among others. Pigment changes associated with light absorption are reported for some white, yellow and brown plasmodial types. In Physarum gyrosum a yellow pigment forms in light which did not show the characteristic flavones present in the white plasmodial stage. Changes in absorption spectra are reported for Physarum polycephalum, Didymium iridis and Didymium squamulosum as the plasmodial pigments change prior to fruiting. Results show a close relationship between the physiology of plasmodial pigmentation and sporulation in the Myxomycete species studied.     

Production of water-soluble yellow pigments via high glucose stress fermentation of Monascus ruber CGMCC 10910

Monascus pigments are secondary metabolites of Monascus species and are mainly composed of yellow pigments, orange pigments and red pigments. In this study, a larger proportion of Monascus yellow pigments could be obtained through the selection of the carbon source. Hydrophilic yellow pigments can be largely produced extracellularly by Monascus ruber CGMCC 10910 under conditions of high glucose fermentation with low oxidoreduction potential (ORP). However, keeping high glucose levels later in the culture causes translation or a reduction of yellow pigment. We presume that the mechanism behind this phenomenon may be attributed to the redox level of the culture broth and the high glucose stress reaction of M. ruber CGMCC 10910 during high glucose fermentation. These yellow pigments were produced via high glucose bio-fermentation without citrinin. Therefore, these pigments can act as natural pigments for applications as food additives.

     

Characterization of an hyperpigmenting mutant of Monascus purpureus IB1: identification of two novel pigment chemical structures

Monascus purpureus IB1 produces about 50-fold higher levels of azaphilone pigments than M. purpureus NRRL1596. Differently pigmented mutants were obtained from M. purpureus IB1 by nitrosoguanidine treatment. A highly pigmented strain, M. purpureus HP14, was found to lack the formation of the classical yellow and orange azaphilones and was found to produce only about 10% of the red azaphilone pigments. The intense color was associated with novel pigments as shown by high-performance liquid chromatography (HPLC). The addition of hexanoic acid to M. purpureus IB1 resulted in higher volumetric and specific red pigment productivity, but in a complete absence of the classical orange azaphilones, while the classical yellow and red azaphilone pigments were severely reduced; new peaks corresponding to less hydrophobic pigments were found in hexanoic-supplemented cultures by HPLC. Purification of pigments from hexanoic-supplemented cultures showed the presence of five new pigments as indicated by the absorption spectra and HPLC analysis. Two of them, R3 and Y3, were characterized by nuclear magnetic resonance as 9-hexanoyl-3-(2-hydroxypropyl)-6a-methyl-9,9a-dihydro-6H-furo[2,3-h]isochromene-6,8(6aH)-dione and 4-[2,4-dihydroxy-6-(3-hydroxybutanethioyloxy)-3-methylphenyl]-3,4-dihydroxy-3,6-dimethylheptanoic acid. These pigments were also found to be present in cultures of the high-producing mutant M. purpureus HP14. These new pigments are less hydrophobic than the classical azaphilones and may have better properties as natural colorants in the food industry.     

Isolation of thermophilic bacteria similar to Thermus sp.

Several thermophilic strains similar to Thermus sp. were isolated from a hot spring in Nha Trang (Vietnam), and a domestic hot water reservoir, respectively. They grow aerobically on a complex medium at a temperature of 55 to 70°C and a pH value of 7 to 8. The cells are gram-negative, non-motile and non-sporulating. They possess yellow or red pigments. The isolated strains are similar to Thermus sp. in regard to the composition of the intracellular fatty-acid fraction as well as the absorption spectra of the extracted cellular pigments.     

不产氧光合细菌光合色素的光氧调控机制

[目的]为不产氧光合细菌光合色素研究提供可行的较系统规范的研究方法和数据,揭示固氮红细菌(Rhodobacter azotoformans 134K20)光合色素光氧适应性机制.[方法]采用光谱法和色谱法对光和氧调控下的类胡萝卜素和细菌叶绿素合成代谢进行了研究.[结果]134K20菌株光照好氧时细胞得率最高.光照厌氧时主要合成3黄、1红、1紫、2绿、2蓝9种色素,黄色素大量表达.有氧时红色素大量表达,且启动2种新的红色素和1种新的紫色素表达,而黄色和蓝绿色素则受氧抑制.黑暗好氧主要合成2黄、3红、2紫、1绿、1蓝9种色素,但不同于光照厌氧.光照好氧时黄色素减少到1种,紫色素含量增加,其余同黑暗好氧.[结论]固氮红细菌(Rhodobacter azotoformans 134K20)是通过PpsR调节途径来调节光合基因表达的.黄色和红色素属于类胡萝卜素.黄色素1属于球形烯系列,其余两种黄色素是新的类胡萝卜素组分.红色素为新的球形烯酮组分,3种红色素极性、峰形和峰位差别显著,正己烷能显示其精细结构.紫色为极性较大的细菌脱镁叶绿素,绿色和蓝色为4种极性不同的细菌叶绿素a中间产物.乙醚甲醇法适合类胡萝卜素的提取,丙酮甲醇冰冻研磨法能快速有效完全提取光合色素.溶剂效应可有效鉴别细菌叶绿素a中间产物.     

Mechanism of fluorescent cocoon sex identification for silkworms Bombyx mori

By using silkworms, Bombyx mori, fluorescent cocoon sex identification (FCSI) as an experimental material, direct fluorescence spectrometry of the cocoon surface indicates that the fluorescent color of silkworm cocoons is made up of two peaks of yellow and blue-purple fluorescence emission. The fluorescent difference between male and female cocoons is attributed to the differential absorption of yellow fluorescent substances by the midgut tissue of 5th instar female silkworms. Thin layer chromatography (TLC) and fluorescent spectra indicate that blue-purple fluorescent substances are composed of at least five blue-purple fluorescent pigments, and yellow fluorescent substances are made up of at least three. UV spectra and AlCl₃ color reaction show that the three fluorescent yellow pigments are flavonoids or their glycosides. Silkworm FCSI is due to selective absorption or accumulation of the yellow fluorescent pigments by the posterior midgut cells of female 5th instar larvae. The cells of the FCSI silkworm midgut, especially the cylinder intestinal cells of the posterior midgut have a component which is a yellow fluorescent pigment-specific binding protein that may be vigorously expressed in the 5th instar larvae.     

Growth kinetics of biopigment production by Thai isolated <Emphasis Type="Italic">Monascus purpureus</Emphasis> in a stirred tank bioreactor

Monascus purpureus is a biopigment-producing fungi whose pigments can be used in many biotechnological and food industries. The growth kinetics of biopigment production were investigated in a liquid fermentation medium in a 5-l stirred tank bioreactor at 30°C, pH 7, for 8 days with 100 rpm agitation and 1.38 × 10⁵ N/m² aeration. Thai Monascus purpureus strains TISTR 3002, 3180, 3090 and 3385 were studied for color production, growth kinetics and productivity. Citrinin as a toxic metabolite was measured from the Monascus fermentation broth. The biopigment productions were detected from fermentation broth by scanning spectra of each strain produced. Results showed a mixture of yellow, orange and red pigments with absorption peaks of pigments occurring at different wavelengths for the four strains. It was found that for each pigment color, the color production from the strains increased in the order TISTR 3002, 3180, 3090, 3385 with 3385 production being approximately 10 times that of 3002. Similar results were found for growth kinetics and productivity. HPLC results showed that citrinin was not produced under the culture conditions of this study. The L*, a* and b* values of the CIELAB color system were also obtained for the yellow, orange and red pigments produced from the TISTR 3002, 3180, 3090 and 3385 strains. The colors of the pigments ranged from burnt umber to deep red.     

Identification and quantification of carotenoid pigments during the embryonic development of the freshwater shrimp Macrobrachium olfersii (crustacea,decapoda)

The principal carotenoids present during the 16‐day embryonic development period and in the first post‐embryonic stage (zoea I) were identified and quantified in the diadromous, neotropical, freshwater shrimp Macrobrachium olfersii, employing differential extraction, absorption spectra analysis and thin layer chromatography. The characteristic crustacean pigments α‐ and β‐carotene and astaxanthin, and a mixture of four unidentified yellow pigments were found. Total carotenoids increase significantly at the mid‐point of embryogenesis (day 8), declining to a minimum in the recently hatched first zoea. This decrease appears to reflect the establishment of carotenoid catabolism, or of carotenoid use in protein and membrane formation and stabilization towards the end of embryogenesis, as well as the depletion of yolk protein reserves by the non‐feeding first zoea.     

Betaxanthins as pigments responsible for visible fluorescence in flowers

Betalains are water-soluble nitrogen-containing pigments present in flowers and fruits of plants of the order Caryophyllales, where they replace anthocyanins. This article describes how flowers containing yellow betaxanthins are fluorescent. Betaxanthins exhibit spectra with excitation maxima between 463 nm and 474 nm and emission maxima between 509 nm and 512 nm. Thus, betaxanthins are able to absorb blue light and emit green light. Relations between fluorescence and the structural properties of the pigments are discussed. For the first time, pictures of flowers naturally emitting light are presented. Yellow flowers of the ornamental plant Portulaca grandiflora were chosen as a model for the studies in fluorescence due to the existence of the white phenotype, which was used as a control. Studies were also performed in Lampranthus productus flowers, which contain dopaxanthin as a single pigment. The visible fluorescence of betaxanthins inside the petal cells was detected in a confocal microscope after laser excitation.     

The major carotenoid pigments of the grain aphid, Sitobion avenae (F.) (Hemiptera: Aphididae)

The economically important grain aphid, Sitobion avenae (F.) shows colour polymorphism, with brown and green forms predominating. Colour is determined both genetically and in response to environmental factors, including nutrition. The biological significance of the colour polymorphism is unknown, although seasonal changes occur in the frequency of colour morphs in the field, whilst the brown morph may have adaptive significance in terms of hymenopterous endoparasitism. The ground colour of aphids is produced by haemolymph pigments, aphins (glucosides) and carotenoids. The latter may be under the synthetic control of intracellular endosymbiotic bacteria. In this study, the major carotenoid pigments of a brown and a green clone of S. avenae were examined using thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC), and their absorbance spectra recorded. Using TLC, the brown clone produced five bands of different R_f, ranging from yellow, to orange-pink to pink in colour. In contrast, the green clone gave only a single yellow band of higher R_f than any of the bands of brown aphids. Following separation of carotenoids by HPLC, brown aphids gave seven peaks and green aphids five. Comparison of absorbance maxima with known published values for carotenoids provides strong evidence for the identification of four of the carotenoid pigments from brown aphids (RB-4, 3,4-didehydrolycopene; RB-5, torulene; RB-6; lycopene; RB-7, γ-carotene) and one from green aphids (RG-2, α-carotene). The other carotenoids remain unidentified. The biosynthesis and possible biological relevance of the various pigments of S. avenae are briefly discussed.     

Red-winged blackbirds Agelaius phoeniceus use carotenoid and melanin pigments to color their epaulets

Over the past three decades, the red‐winged blackbird Agelaius phoeniceus has served as a model species for studies of sexual selection and the evolution of ornamental traits. Particular attention has been paid to the role of the colorful red‐and‐yellow epaulets that are striking in males but reduced in females and juveniles. It has been assumed that carotenoid pigments bestow the brilliant red and yellow colors on epaulet feathers, but this has never been tested biochemically. Here, we use high‐performance liquid chromatography (HPLC) to describe the pigments present in these colorful feathers. Two red ketocarotenoids (astaxanthin and canthaxanthin) are responsible for the bright red hue of epaulets. Two yellow dietary precursors pigments (lutein and zeaxanthin) are also present in moderately high concentrations in red feathers. After extracting carotenoids, however, red feathers remained deep brown in color. HPLC tests show that melanin pigments (primarily eumelanin) are also found in the red‐pigmented barbules of epaulet feathers, at an approximately equal concentration to carotenoids. This appears to be an uncommon feature of carotenoid‐based ornamental plumage in birds, as was shown by comparable analyses of melanin in the yellow feathers of male American goldfinches Carduelis tristis and the red feathers of northern cardinals Cardinalis cardinalis, in which we detected virtually no melanins. Furthermore, the yellow bordering feathers of male epaulets are devoid of carotenoids (except when tinged with a carotenoid‐derived pink coloration on occasion) and instead are comprised of a high concentration of primarily phaeomelanin pigments. The dual pigment composition of red epaulet feathers and the melanin‐only basis for yellow coloration may have important implications for the honesty‐reinforcing mechanisms underlying ornamental epaulets in red‐winged blackbirds, and shed light on the difficulties researchers have had to date in characterizing the signaling function of this trait. As in several other birds, the melanic nature of feathers may explain why epaulets are used largely to settle aggressive contests rather than to attract mates.     

Oil droplets of bird eyes: microlenses acting as spectral filters

An important component of the cone photoreceptors of bird eyes is the oil droplets located in front of the visual-pigment-containing outer segments. The droplets vary in colour and are transparent, clear, pale or rather intensely yellow or red owing to various concentrations of carotenoid pigments. Quantitative modelling of the filter characteristics using known carotenoid pigment spectra indicates that the pigments’ absorption spectra are modified by the high concentrations that are present in the yellow and red droplets. The high carotenoid concentrations not only cause strong spectral filtering but also a distinctly increased refractive index at longer wavelengths. The oil droplets therefore act as powerful spherical microlenses, effectively channelling the spectrally filtered light into the photoreceptor''s outer segment, possibly thereby compensating for the light loss caused by the spectral filtering. The spectral filtering causes narrow-band photoreceptor spectral sensitivities, which are well suited for spectral discrimination, especially in birds that have feathers coloured by carotenoid pigments.     

微生物黄色素的研究进展

对来源于微生物的天然黄色素的研究进行了详细概述, 尤其对红曲黄色素的生产、安全性以及黄色素的合成代谢机理研究进行了详细论述, 最后对红曲黄色素的应用前景及其未来研究重点进行了展望, 并对研究中存在的问题进行了分析。     

不同叶色三叶海棠叶片成色色素分析

结合民族植物学和药理学的研究方法,对西双版纳地区傣族、哈尼族和基诺族等3个少数民族民间利用番石榴（Psidium guajava）、余甘子（Phyllanthus emblica）和水柳（Homonoia riparia）的传统知识进行调查研究及体外抗菌活性实验。结果表明：番石榴和余甘子在村寨中较为常见,当地少数民族将其种植于庭院中,常作为果蔬食用,食用番石榴嫩叶可缓解拉肚子的症状,治疗腹痛、腹泻。水柳生长在水边,傣族会将其叶作为腌酸鱼的配料之一。根据文献记载,番石榴、余甘子和水柳的叶部位作为药使用时,常煎水外洗,治疗皮肤瘙痒。对这3种药用植物叶部位采用80%乙醇浸泡制备的提取物进行体外抗菌实验,结果显示番石榴、余甘子和水柳3种药用植物对金黄色葡萄球菌和大肠埃希菌均有较好的抑菌和杀菌活性,其最小抑菌浓度MIC在98~390 μg·mL 1之间,最小杀菌浓度MBC在98~781 μg·mL 1之间。番石榴和水柳叶对铜绿假单胞菌有一定抑菌和杀菌活性,其MIC和MBC范围均为6 250~12 500 μg·mL 1。由此可见,这3种药用植物的民间利用具有一定的合理性和药用开发价值。     

Dietary carotenoids change the colour of Southern corroboree frogs

Animal coloration can be the result of many interconnected elements, including the production of colour‐producing molecules de novo, as well as the acquisition of pigments from the diet. When acquired through the diet, carotenoids (a common class of pigments) can influence yellow, orange, and red coloration and enhanced levels of carotenoids can result in brighter coloration and/or changes in hue or saturation. We tested the hypothesis that dietary carotenoid supplementation changes the striking black and yellow coloration of the southern corroboree frog (Pseudophryne corroboree, Amphibia: Anura). Our dietary treatment showed no measurable difference in colour or brightness for black patches in frogs. However, the reflectance of yellow patches of frogs raised on a diet rich in carotenoids was more saturated (higher chroma) and long‐wave shifted in hue (more orange) compared to that of frogs raised without carotenoids. Interestingly, frogs with carotenoid‐poor diets still developed their characteristic yellow and black coloration, suggesting that their yellow colour patches are a product of pteridines manufactured de novo.     

Lutein-based plumage coloration in songbirds is a consequence of selective pigment incorporation into feathers

Many birds obtain colorful carotenoid pigments from the diet and deposit them into growing tissues to develop extravagant red, orange or yellow sexual ornaments. In these instances, it is often unclear whether all dietary pigments are used as integumentary colorants or whether certain carotenoids are preferentially excluded or incorporated into tissues. We examined the carotenoid profiles of three New World passerines that display yellow plumage coloration—the yellow warbler (Dendroica petechia), common yellowthroat (Geothlypis trichas) and evening grosbeak (Coccothraustes vespertinus). Using high-performance liquid chromatography, we found that all species used only one carotenoid—lutein—to color their plumage yellow. Analyses of blood carotenoids (which document those pigments taken up from the diet) in two of the species, however, revealed the presence of two dietary xanthophylls—lutein and zeaxanthin—that commonly co-occur in plants and animals. These findings demonstrate post-absorptive selectivity of carotenoid deposition in bird feathers. To learn more about the site of pigment discrimination, we also analyzed the carotenoid composition of lipid fractions from the follicles of immature yellow-pigmented feathers in G. trichas and D. petechia and again detected both lutein and zeaxanthin. This suggests that selective lutein incorporation in feathers is under local control at the maturing feather follicle.     

Physical and chemical cues influencing the oviposition behaviour of Aphidius ervi

The oviposition behaviour of the aphid parasitoid Aphidius ervi Haliday is influenced by both chemical and physical cues. Oviposition attack responses were elicited by paint pigments sealed into the tip of a glass capillary tube. Parasitoids reacted to yellow pigments with repeated oviposition attack responses, but they did not react to green pigments. The spectrum of reflected light from the yellow pigments was very similar to that from the `green' natural host Acyrthosiphon pisum (Harris), with a high proportion of the total radiation energy being emitted in the yellow-orange wavebands (580–660 nm). Pea aphid cornicle secretion also elicited oviposition attack responses, which were not exclusively induced by its pale yellow-green colour. In fact, the oviposition attack response to capillary tips coated with cornicle secretion remained evident under red light conditions, which, in contrast, nearly completely suppressed the response to yellow pigments. Chemical compounds from cornicle secretion do not appear to be involved in parasitoid orientation, even though they stimulate intense oviposition attack responses. Olfactometer experiments showed that the putative kairomone involved acts only at very short range or on contact. Host exuviae, which also elicited strong and persistent oviposition reactions from A. ervi females, appear to be a good alternative source of ovipositional kairomone(s). This work confirms the existence of an aphid cuticular kairomone.     

Light-induced changes of carotenoid pigments in anaerobic cells of the aerobic photosynthetic bacterium,Roseobacter denitrificans (Erythrobacter species OCh 114): reduction of spheroidenone to 3,4-dihydrospheroidenone

Roseobacter denitrificans, previously named Erythrobacter species OCh 114, synthesized spheroidenone as a major carotenoid under aerobic dark conditions. When the dark-grown cells were subjected to illumination under anacrobic conditions, many unknown yellow pigments appeared and a considerable amount of spheroidenone disappeared. Absorption maxima of these pigments were blue-shifted from those of spheroidenone. The most abundant of the pigments was isolated, and its chemical structure was determined as 3,4-dihydrospheroidenone on spectroscopic and chemical evidence. Presumably, over-reduction of the photosynthetic apparatus interfered with normal photosynthetic electron transfer and resulted in photoreduction of C=C double bond at the 3,4-position of spheroidenone.     

Structure and biosynthesis of 5-deoxyfusarubin and anhydro-5-deoxyfusarubin,naphthaquinone pigments from Nectria haematococca

Two naphthaquinone pigments, 5-deoxyfusarubin and anhydro-5-deoxyfusarubin, were isolated from a yellow strain of the fungus Nectria haematococca. The ¹³C NMR spectra of 2 biosynthetically labelled from [1-¹³C]acetate confirmed the structures of the pigments and established the heptaketide origin of the molecules.     

Chromatic adaptation in lichen phyco- and photobionts

The effect of light quality on the photosynthetic pigments as chromatic adaptation in 8 species of lichens were examined. The chlorophylls, carotenoids in 5 species with green algae as phycobionts (Cladonia mitis, Hypogymnia physodes, H. tubulosa var. tubulosa and subtilis, Flavoparmelia caperata, Xanthoria parietina) and the chlorophyll a, carotenoids and phycobiliprotein pigments in 3 species with cyanobacteria as photobionts (Peltigera canina, P. polydactyla, P. rufescens) were determined. The total content of photosynthetic pigments was calculated according to the formule and particular pigments were determined by means CC, TLC, HPLC and IEC chromatography. The total content of the photosynthetic pigments (chlorophylls, carotenoids) in the thalli was highest in red light (genus Peltigera), yellow light (Xanthoria parietina), green light (Cladonia mitis) and at blue light (Flavoparmelia caperata and both species of Hypogymnia). The biggest content of the biliprotein pigments at red and blue lights was observed. The concentration of C-phycocyanin increased at red light, whereas C-phycoerythrin at green light.