Morphological Characterization of Three Phenotypes of the Isopod Armadillidium vulgare

The morphological characteristics and ommochrome quantity in the integument of red, white, and wild type (black-grey) Armadillidium vulgare were studied. The red phenotype was found to possess two kinds of immature ommochrome pigment granules within its pigment cells, in addition to mature pigment granules. The immature granules seemed to contain uniformly distributed fibrilles, or to have an electron-dense central region surrounded by an electron-lucent outer edge. Since these immature pigment granules were typically observed to be distributed along with the mature ones, and were also more easily extractable than the wild type's, it is hypothesized that ommochrome granule maturation in the red phenotype may occur slowly due to a defect in the pigment granule internal process which combines pigments with matrix proteins. Regarding the white phenotype, although its pigment cells were undeveloped, several large-sized vesicles containing a small amount of electron-dense material appeared in the pigment cell cytoplasm. The wild and red type males of A. vulgare were found to have an ommochrome content twice as large as that of the corresponding females, with no ommochrome pigment being detected in the white phenotype. The genetic relationship between the white and red phenotypes was discussed using as a basis the observed pigment granule structure.     

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.     

Studies on red pigments excreted by cells of Chlorella protothecoides during the process of bleaching induced by glucose or acetate II. Mode of formation of the red pigments

In parallel with the studies reported in the preceding paper(I), the modes of production of characteristic red pigmentsby Chlorella protothecoides cells were investigated under variousculture conditions, (i) During the course of "acetate-bleaching"of algal cells, excretion of red pigments in the medium proceededwith simultaneous disappearance of chlorophyll from algal cells.The total amount (weight) of the red pigments excreted intomedium was slightly less than that of the chlorophyll lost.No red pigment was detectable within the bleaching algal cells.Carotenoids were found to increase or remain nearly constantin their quantities per culture during the process of bleaching,(ii) In a later phase of "glucose-bleaching" some red pigmentswere found to be present inside as well as outside the algalcells, and the excreted pigments underwent further changes turningcolourless, (iii) Both the production of red pigments and disappearanceof chlorophyll were suppressed by light and this light effectwas insensitive to CMU. (iv) During the process of "regreening"of "glucose-bleached" algal cells, no production of red pigmentswas observed either in or outside the algal cells. Based on these results we concluded that the red pigments areproduced from chlorophyll during the bleaching process of algalcells induced by an organic carbon source. (Received July 23, 1968; )     

Structure and histochemical organization of the spleen of Agama stellio (Sauria: Agamidae) and Chalcides ocellatus (Sauria: Scincidae)

The spleen of Agama stellio is composed mainly of red pulp; the white pulp is poorly developed, and its clusters are scattered throughout the organ and contain lymphocytes, reticular cells, and some plasma cells. The red pulp consists of clear reticular cells intermingled with blood cells, sinusoids, and pigment cells. The spleen of Chalcides ocellatus is encapsulated by connective tissue and is composed of white and red pulp. The white pulp consists of lymphoid tissue that surrounds the central arterioles, forming the periarteriolar lymphocyte sheath (PALS). The red pulp is composed of a system of venous sinuses and cords. The results of various histochemical procedures designed to demonstrate mucosubstances, proteins, and nucleic acids indicate that the spleen in these species resembles the mammalian spleen. © 1993 Wiley-Liss, Inc.     

豹纹鳃棘鲈体色变异的色素细胞差异分析

为了揭示豹纹鳃棘鲈(Plectropomus leopardus)体色变异机制,研究选取了不同体色个体的样本,利用石蜡切片、冰冻切片及体视显微镜观察等方法揭示不同皮肤部位色素细胞的类型、分布和数量的差异,并对应激和非应激状态下色素细胞的变化进行了研究。结果显示,黑色素细胞在背部和尾部分布比较密集,在腹部较为稀疏,黑色个体的黑色素细胞数量较红色个体多;在应激状态下个体能迅速发生体色变化,主要由于色素细胞快速扩张和收缩导致。研究为进一步揭示豹纹鳃棘鲈体色变异的分子机制和优良品种选育奠定了基础。     

Inhibition of neural crest cell differentiation by embryo ectodermal extract.

The white mutation in Mexican axolotls has long been thought to be a defect associated with the embryonic extracellular environment, but not with embryonic neural crest cells. Thus it was believed that pigment cells in white axolotls disappear from the skin during early development, not because they are intrinsically defective but because they have no choice but to move into an unfavorable environment. We present evidence to suggest that: (1) white neural crest cells are in fact intrinsically different from dark (wild-type) cells, and (2) an inhibitor is produced in white embryonic ectoderm that actively suppresses the migration, differentiation, and survival of pigment cells in this animal. How these observations fit into the existing body of literature on the white mutant and a model for how the white phenotype might develop are discussed.     

LED光质对茄子果实品质及抗氧化能力的影响

采用发光二极管(LED)精量调制光质和光强,以白光为对照,研究红光、蓝光和红蓝组合光对‘布利塔’长茄果实品质、抗氧化能力及产量的影响.结果表明: 蓝光处理下,茄子果肉中可溶性蛋白、游离氨基酸和茄皮中花青素含量显著高于其他处理,分别比对照高15.1%、27.2%和73.6%,但果肉中类黄酮、总酚含量及产量显著低于其他处理;红光处理下,茄皮中类黄酮含量显著高于其他处理,但果肉中维生素C(Vc)和可溶性蛋白含量显著低于其他处理;红蓝组合光处理下,果肉中可溶性糖及茄皮中总酚、红色素、黄色素含量、总抗氧化能力以及产量均显著高于其他处理,其中茄皮中总抗氧化能力及产量分别比对照高43.5%和43.4%;而白光处理下,果肉中Vc、类黄酮和总酚含量及总抗氧化能力最高.茄皮中总酚及果肉中Vc含量与其总抗氧化能力呈显著正相关.设施栽培条件下,适当补充蓝光或红光均有利于改善茄子部分品质,红蓝组合光更有利于改善茄皮品质与产量形成.     

集球藻对盐胁迫的生理适应及细胞结构变化

盐胁迫是影响荒漠区土壤藻类生存的重要环境因子。集球藻是一种广泛分布于生物土壤结皮中的球状绿藻, 能够积累红色素(如虾青素)和油滴, 显示出其独特的生理特性和潜在的应用价值。目前对集球藻的生理、细胞结构以及色素积累的研究非常匮乏。以从荒漠生物结皮中分离的一种集球藻为材料, 在实验室条件下研究盐胁迫对集球藻生物量、光合活性、膜脂过氧化产物丙二醛含量、细胞可溶性蛋白质含量和可溶性糖含量以及细胞结构的影响。研究结果表明, 与对照处理相比, 盐胁迫导致集球藻生物量和光合活性的显著降低, 细胞可溶性蛋白和可溶性糖呈现一定的积累。同时盐处理导致集球藻膜脂丙二醛含量大量增加, SOD和CAT 活性升高。研究还表明, 对照处理下细胞结构完整, 细胞器形态清晰, 生长后期有大量脂肪体积累。在盐处理下藻体细胞形态结构出现阶段性破坏特征和脂肪体以及淀粉粒的积累, 此外细胞器结构模糊和消失, 细胞出现质壁分离和空泡化等。研究为更好地揭示集球藻在盐胁迫环境中的生理适应特性、微结构特征以及色素积累机制具有重要的科学意义, 并为该藻的基础和应用研究提供实验资料。       

Chromatophore Organs, Reflector Cells, Iridocytes and Leucophores in Cephalopods

The chromatophore organs of Lohgo are each composed of fivetypes of cells: a central pigment cell: radially arranged, obliquelystriated muscle fibers: neuronal processes; glial cells: andan investment of sheath cells. Sheath cells are absent in Octopuschromatophore organs. The cycle of expansion and retractionof a chromatophore organ may occur within the order of a second.It is clear that the muscle fibers expand the pigment cell andspread out the pigment granules. The pigment is contained withinan unusual, filamentous, cytoplasmic compartment called thecytoelastic sacculus. This compartment has elastic properties. Reflector cells and iridocytes produce structural colors eventhough their components are colorless. Reflector cells in Octopusbear peripheral sets of leaf-like reflecting lamellae calledreflectosomes: these contain proteinaceous platelets with ahigh refractive index (1.42). In each reflectosome the reflectinglamellae are separated by gaps that are about equal to the thicknessof the lamellae, but have a lower refractive index (1.33). Reflectosomesare believed to reflect light and to function as thin-film interferencedevices. Iridocytes in squid and cuttlefish contain iridosomes that arealso composed of sets of ribbon-like platelets but these arelocated centrally within the cell body. The platelets are usuallyoriented on edge with respect to the surface of the skin. Thepossibility that dermal iridocytes may act as diffraction gratingsis discussed. Leucophores have thousands of processes that containglobules of protein with a high refractive index. These cellsscatter light of all wave lengths and appear white in whitelight.     

Effect of red pigment on amyloidization of yeast

Amyloid-bound thioflavin T fluorescence was studied in lysates of yeast strains that carry mutations in the ADE1 or ADE2 genes and accumulate red pigment as a result of the polymerization of aminoimidazole ribotide (an intermediate of adenine biosynthesis). The fluorescence is drastically enhanced in cells grown in media with high concentrations of adenine (100 mg/l), which suppresses the accumulation of red pigment. Mutations that block the first stages of purine biosynthesis de novo also impede the accumulation of red pigment and produce the same effect on thioflavin fluorescence. Mutations in ADE1 or ADE2 genes in originally white prototrophic strains considerably suppress fluorescence. The fraction of protein polymers was studied by agarose gel electrophoresis, which permitted us to conclude that reduced fluorescence intensity was associated with decreased amyloid content in cells that accumulate red pigment. Model experiments with insulin fibers demonstrate that red pigment binds fibrils and blocks their interaction with thioflavin T. A comparison of lysate pellet proteins from red and white isogenic strains separated by 2D electrophoresis followed by MALDI analysis allowed us to identify 23 pigment-dependent proteins. These proteins mostly belong to functional classes of chaperones and proteins involved in glucose metabolism, which closely correspond to the prion-dependent proteins that we characterized previously. We suppose that the binding of red pigment with amyloid fibrils prevents the generation of prion aggregates and impedes prion propagation by blocking fibril contact with chaperones.     

A functional zeaxanthin epoxidase from red algae shedding light on the evolution of light‐harvesting carotenoids and the xanthophyll cycle in photosynthetic eukaryotes

The epoxy‐xanthophylls antheraxanthin and violaxanthin are key precursors of light‐harvesting carotenoids and participate in the photoprotective xanthophyll cycle. Thus, the invention of zeaxanthin epoxidase (ZEP) catalyzing their formation from zeaxanthin has been a fundamental step in the evolution of photosynthetic eukaryotes. ZEP genes have only been found in Viridiplantae and chromalveolate algae with secondary plastids of red algal ancestry, suggesting that ZEP evolved in the Viridiplantae and spread to chromalveolates by lateral gene transfer. By searching publicly available sequence data from 11 red algae covering all currently recognized red algal classes we identified ZEP candidates in three species. Phylogenetic analyses showed that the red algal ZEP is most closely related to ZEP proteins from photosynthetic chromalveolates possessing secondary plastids of red algal origin. Its enzymatic activity was assessed by high performance liquid chromatography (HPLC) analyses of red algal pigment extracts and by cloning and functional expression of the ZEP gene from Madagascaria erythrocladioides in leaves of the ZEP‐deficient aba2 mutant of Nicotiana plumbaginifolia. Unlike other ZEP enzymes examined so far, the red algal ZEP introduces only a single epoxy group into zeaxanthin, yielding antheraxanthin instead of violaxanthin. The results indicate that ZEP evolved before the split of Rhodophyta and Viridiplantae and that chromalveolates acquired ZEP from the red algal endosymbiont and not by lateral gene transfer. Moreover, the red algal ZEP enables engineering of transgenic plants incorporating antheraxanthin instead of violaxanthin in their photosynthetic machinery.     

Abstracts of papers read at the winter meeting at the university of Newcastle Upon Tyne

Young plants of Laminaria hyperborea collected from the field were grown for 2·5–4 weeks in blue, green, red and white (simulated underwater) light fields at 5, 20 and 100 μmol m^-2s^-1. The absolute concentrations of all pigments showed little variation with irradiance in green and white light, but decreased in high irradiances of red and blue light. The ratio of fucoxanthin to chlorophyll a also increased in the latter treatments, as did the chlorophyll c:a ratio in bright red light. There was little difference in the action spectrum for photosynthesis between the different light qualities at any one irradiance, but the action spectra for plants grown at 100 μmol m^-2s^-1 showed deeper troughs and higher peaks than those for plants grown at lower irradiances. Gross photosynthesis per unit of thallus area at 10 μmol m^-2s^-1 decreased in plants with low total pigment concentrations, but the photosynthesis per unit of pigment concentration increased. This suggestion of self-shading of pigment molecules within the algal thalli was supported by a flattening of the action spectrum in plants with higher chlorophyll a contents. The variations observed between the action spectra for different plants could thus be attributed to the decrease in pigment content at high irradiances, and not to the light quality in which the plants were grown.     

Sub-cellular Localisation of the White/Scarlet ABC Transporter to Pigment Granule Membranes Within the Compound Eye of Drosophila Melanogaster

The white, scarlet, and browngenes of Drosophila melanogasterencode ABC transporters involved with the uptake and storage of metabolic precursors to the red and brown eye colour pigments. It has generally been assumed that these proteins are localised in the plasma membrane and transport precursor molecules from the heamolymph into the eye pigment cells. However, the immuno-electron microscopy experiments in this study reveal that the White and Scarlet proteins are located in the membranes of pigment granules within pigment cells and retinula cells of the compound eye. No evidence of their presence in the plasma membrane was observed. This result suggests that, rather than tranporting tryptophan into the cell across the plasma membrane, the White/Scarlet complex transports a metabolic intermediate (such as 3-hydroxy kynurenine) from the cytoplasm into the pigment granules. Other functional implications of this new finding are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

A prodiginine pigment toxic to embryos and larvae of Crassostrea virginica

The red pigment produced by a marine Pseudomonas sp. which causes abnormal development and mortality in developing embryos of the American oyster, Crassostrea virginica, was analyzed. A comparative study of a nonpigmented and two pigmented mutants of the red parental strain indicated that virulence was associated and varied with pigmentation. The use of sonicated cells supported lysing of the pseudomonad cells as the most probable means of pigment release. Crude pigment extracted from the red parental strain and its yellow mutant was toxic to developing oyster embryos. Neither the “pigment” extracted from the white mutant nor dimethyl sulfoxide, used for dissolving the extract, was toxic. Three pigment fractions were demonstrated by thin-layer chromatography even after purification. Studies indicate that only the fraction corresponding to R₁ 0.41 was necessary for virulence. The virulent pigment fraction was identified as belonging to the prodiginine group.     

Growth and pigment composition in the red alga <Emphasis Type="Italic">Halymenia floresii</Emphasis> cultured under different light qualities

Halymenia floresii is an edible species consumed in some Asian markets. In the Yucatan peninsula coast of Mexico, H. floresii dominates rocky substrata between 3 and 40 m where it grows up to 50 cm high. After analyzing the seasonal pattern of pigment content on H. floresii, we evaluate if and how the spectral composition of light affects growth and pigment dynamics under laboratory cultivation. Unialgal cultures were exposed to white, blue, red and green light in a 3-week experiment. Green light resulted in the highest algal growth rates. Synthesis of chlorophyll a, α-carotene and lutein, but not of β-carotene, was induced by white or green light. Phycocyanin synthesis was stimulated by blue light and phycoerythrin synthesis by blue or red light. Light quality treatments may be used to manipulate pigment composition in Halymenia floresii cultures.     

Phagocytosis in the spleen of the sunfish Lepomis spp.

A histological investigation of the filtering function of the spleen of the sunfish Lepomis spp. was conducted by light, scanning, and transmission electron microscopy. The parenchyma of the organ is predominantly red pulp, a system of splenic cords and sinuses. The white pulp consists of loose lymphoid tissue which forms a cuff around the pulp arteries. Filtering of particulate matter from the blood occurs in the red pulp by phagocytes of the pulp cords and ellipsoids (periarterial macrophage sheaths). The ellipsoids are pale-staining cuffs of macrophages and reticular cells in a framework of reticular fibres surrounding the arterial capillaries. Destruction of effete blood cells (especially erythrocytes) is confined to the pigment nodules; particulate matter is not taken up by the nodules. These yellow-brown bodies are dispersed throughout the red pulp and are bounded by a reticular capsule. They contain masses of phagocytes and have the appearance of a morula. They are associated with blood vessels and are surrounded by sinusoids. Prussian Blue stain shows the presence of haemosiderin within their phagocytes. The phagocytes of the pigment nodules are filled with inclusions such as residual bodies, siderosomes, and fragments of erythrocytes. The early filtering of particulate matter by the phagocytes of the pulp cords and ellipsoids may allow for a more efficient phagocytosis of erythrocytes by the pigment nodules, followed by storage and reutilization of iron-containing compounds uncontaminated by other phagocytosed material.     

The effect of light and 2,4-D on anthocyanin production in Oxalis reclinata callus

In vitro cultures of O. reclinata accumulate red anthocyanin pigments. Two callus lines were established from O. reclinata, one red and the other non-pigmented. The red callus accumulated cyanidin-3-glucoside as a major pigment. Light irradiation induced anthocyanin synthesis in white callus, resulting in a heterogenous red callus line being formed. The incubation of red and white callus cultures in the dark or at low-light resulted in the repression of red pigment accumulation. The application of 2,4-D (1.0 mg l^-1) inhibited pigment production in the white callus and decreased anthocyanin accumulation in the red callus. The polypeptide composition of the red and white callus lines from O. reclinata were compared using two-dimensional electrophoresis. The red callus had a larger subset of neutral and acidic polypeptides.     

Geochemical Evidence of the Seasonality,Affinity and Pigmenation of Solenopora jurassica

Solenopora jurassica is a fossil calcareous alga that functioned as an important reef-building organism during the Palaeozoic. It is of significant palaeobiological interest due to its distinctive but poorly understood pink and white banding. Though widely accepted as an alga there is still debate over its taxonomic affinity, with recent work arguing that it should be reclassified as a chaetetid sponge. The banding is thought to be seasonal, but there is no conclusive evidence for this. Other recent work has, however demonstrated the presence of a unique organic boron-containing pink/red pigment in the pink bands of S. jurassica. We present new geochemical evidence concerning the seasonality and pigmentation of S. jurassica. Seasonal growth cycles are demonstrated by X-ray radiography, which shows differences in calcite density, and by varying δ¹³C composition of the bands. Temperature variation in the bands is difficult to constrain accurately due to conflicting patterns arising from Mg/Ca molar ratios and δ¹⁸O data. Fluctuating chlorine levels indicate increased salinity in the white bands, when combined with the isotope data this suggests more suggestive of marine conditions during formation of the white band and a greater freshwater component (lower chlorinity) during pink band precipitation (δ¹⁸O). Increased photosynthesis is inferred within the pink bands in comparison to the white, based on δ¹³C. Pyrolysis Gas Chromatography Mass Spectrometry (Py-GCMS) and Fourier Transform Infrared Spectroscopy (FTIR) show the presence of tetramethyl pyrrole, protein moieties and carboxylic acid groups, suggestive of the presence of the red algal pigment phycoerythrin. This is consistent with the pink colour of S. jurassica. As phycoerythrin is only known to occur in algae and cyanobacteria, and no biomarker evidence of bacteria or sponges was detected we conclude S. jurassica is most likely an alga. Pigment analysis may be a reliable classification method for fossil algae.     

Unusual development of light-reflecting pigment cells in intact and regenerating tail in the periodic albino mutant of Xenopus laevis

Unusual light-reflecting pigment cells, “white pigment cells”, specifically appear in the periodic albino mutant (a ^p /a ^p ) of Xenopus laevis and localize in the same place where melanophores normally differentiate in the wild-type. The mechanism responsible for the development of unusual pigment cells is unclear. In this study, white pigment cells in the periodic albino were compared with melanophores in the wild-type, using a cell culture system and a tail-regenerating system. Observations of both intact and cultured cells demonstrate that white pigment cells are unique in (1) showing characteristics of melanophore precursors at various stages of development, (2) accumulating reflecting platelets characteristic of iridophores, and (3) exhibiting pigment dispersion in response to α-melanocyte stimulating hormone (α-MSH) in the same way that melanophores do. When a tadpole tail is amputated, a functionally competent new tail is regenerated. White pigment cells appear in the mutant regenerating tail, whereas melanophores differentiate in the wild-type regenerating tail. White pigment cells in the mutant regenerating tail are essentially similar to melanophores in the wild-type regenerating tail with respect to their localization, number, and response to α-MSH. In addition to white pigment cells, iridophores which are never present in the intact tadpole tail appear specifically in the somites near the amputation level in the mutant regenerating tail. Iridophores are distinct from white pigment cells in size, shape, blue light-induced fluorescence, and response to α-MSH. These findings strongly suggest that white pigment cells in the mutant arise from melanophore precursors and accumulate reflecting platelets characteristic of iridophores.