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PubMed1999

Ultrastructural and biochemical analysis of epidermal xanthophores and dermal chromatophores of the teleost Sparus aurata.

We have studied the pigmentary system of the teleost Sparus aurata skin by electron microscopy and chromatographic analysis. Under electron microscopy, we found the dermis to contain the three major types of recognized chromatophores: melanophores, xanthophores and iridophores. Melanophores were more abundant in the dorsal region, whereas the iridophores were more abundant in the ventral region. The most important discovery was that of epidermal xanthophores. Epidermal xanthophores were the only chromatophores in the epidermis, something only found in S aurata and in a teleost species living in the Antartic sea. In contrast, the biochemical analysis did not establish any special characteristics: we found pteridine and flavin pigments located mostly in the pigmented dorsal region. Riboflavin and pterin were two of the most abundant coloured pigment types, but other colourless pigments such as xanthopterin and isoxanthopterin were also detected.

Animals↗
PubMedDate not supplied

[Influence of reduced pterine and juvenile hormone on the pigmentation of the phasms Carausius morosus (author's transl)].

Tetrahydrofolic acid and dimethyltetrahydropterine, FH4 and DMH4P, have an antagonist action. FH4 darkens the phasms. DMH4P and the tryptophane have an inhibitrice influence on the melanisation, probably by the increase of the synthesis or the release of serotonin, in the hypoderm. For the adult phasm remaining ivory, xanthopterin must be added in the treatment. The addition of diapausing chrysalids pieridae extract (containing juvenile hormone JH) and treated by FH4, in the treatment precedent, transmits the pgimentary effect at the first generation, which presents a strong percentage of dark or ivory phasms.

Animals↗
PubMed1979

Pterin deaminase from Bacillus megaterium. Purification and properties.

A pterin deaminase catalyzing the hydrolytic deamination of various pteridines was found in the bacterium, Bacillus megaterium, and partially purified from bacterial extract. The specific activity was raised 90-fold over that of the crude extract. The pH optimum is around 7.3, and the Km value for 6-carboxypterin is 1.3 mM. The molecular weight of the enzyme was estimated by gel filtration to be about 110,000. The enzyme deaminated pterin, 6-carboxypterin, biopterin, 6-methylpterin, 7-methylpterin, xanthopterin, 6-hydroxymethylpterin, sepiapterin, isosepiapterin, folic acid, and 6,7-dimethylpterin to their corresponding lumazines, whereas guanine, 7-carboxypterin, leucopterin, isoxanthopterin, and 6-methylisoxanthopterin did not serve as substrates. The enzyme was inhibited by PCMB and 8-azaguanine.

Aminohydrolases↗
PubMed1987

Evaluation of pteridines in patients with different tumors.

During the last few years interesting results have been reported on alterations of folates and on pterins in tissues and body fluids from patients with malignant tumors. For some diseases defects in pterin biosynthesis was described. Plasma and blood cells from various tumor patients were analyzed to obtain information on the role of pteridine pattern and the pathological alterations of cells and on the relevance of some pteridine levels for diagnosis of cancer and other diseases. In the oxidized and deproteinized blood fractions (plasma, white cells, and erythrocytes) nine pteridines (pterin-6-carboxylic acid, xanthopterin, neopterin, monapterin, isoxanthopterin, lumazine, biopterin, 6-hydroxymethylpterin, and pterin) were quantified after their separation by reverse-phase high-performance liquid chromatography with fluorescence detection at exc/em = 360/460 nm.

Adult↗
PubMed1980

Permanent cell lines from erythrophoromas in goldfish (Carassius auratus).

Attempts to establish permanent cell lines from spontaneous erythrophoromas (tumors derived from red pigment cells or erythrophores) of goldfish were made with the use of biopsy specimens from 12 tumors in 10 fish. Three cell lines were established that grew in vitro in synthetic medium (L-15 or Dulbecco's modified Eagle's minimum essential medium) supplemented with 20% fetal bovine serum for more than 8 months. One of these lines (GEM-81) with high proliferative activity was cultured for over 200 generations without an obvious change in growth rate. From this cell line, clonal cultures were obtained that formed clones with relatively intense yellow pigmentation. Descendants of these cell lines and clones contained low but detectable amounts of pteridine pigments (such as 7-hydroxybiopterin, biopterin, xanthopterin, and isoxanthopterin) and numerous cytoplasmic organelles analogous to pterinosomes. Both these characteristics are phenotypic markers of normal erythrophores and their neoplastic counterparts. After numerous subcultivations, these long-term cultures differed from those of the initial explants in having much lower contents of total pteridines and relatively lowered contents of 7-hydroxybiopterin. As manifestations of their neoplastic origins, all cell lines examined showed disoriented growth with dense focal mounding in monolayer cultures. The population doubling time of the uncloned GEM-81 cell line was 31 hours at 35 degrees C over a feeder cell layer and 3 days at 25 degrees C without feeder cells. Injection of cultured cells (1.5 x 10(7) cells/fish) into normal goldfish that had not been immunosuppressed did not give rise to tumors within 5 months.

Animals↗
PubMedDate not supplied

[Determination of folacin in the liver with the use of its enzymes].

A method of instituting hydrolysis by using enzymes of the examined liver is proposed as an adjunct to the formerly elaborated fluorometric procedure of determining folacin in the liver. The fermentative hydrolysis is conducted in two stages. The purpose of the first of them is to split the combined form of folacin under the effect of the examined liver conjugases; the second stage involves transformation of xanthopterin contained in the liver into leucopterin by xanthinoxidase of the liver. When utilizing enzymes of the examined liver the need for producing and application of the enzymatic preparation made of the pig kidneys falls away, this simplifying the fluorometric determination of folacin in the liver and increasing its accuracy.

Animals↗
PubMed1953

Isoxanthopterin.

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Humans↗
PubMed1985

Pteridine formation during lectin-induced lymphocyte activation.

After iodine oxidation, biopterin, 6-hydroxymethylpterin, and 6-formylpterin were identified in mouse spleen lymphocytes by means of reverse-phase HPLC, Crithidia assay, and oxidative degradation. Concanavalin A activation induces a 30-fold increase in the pteridine amounts; biopterin as well as the sum of the carbinol and the aldehyde attain levels of 6-8 X 10(-12) mol/10(6) cells. The most rapid increase occurs during the first 24 hr. Thus, pteridine accumulation precedes the period of lymphocyte proliferation; maximum DNA synthesis was found after 72 hr. Biopterin remains largely inside the cells, whereas 6-hydroxymethylpterin and 6-formylpterin were found in the supernatant if the stimulated cells were subsequently incubated in a phosphate buffered salt solution (PBS). Isoxanthopterin was found in the PBS supernatant of control cells that previously were kept in medium alone rather than subjected to lectin stimulation. Only minimal amounts were found inside these cells, and this pterin was absent from the stimulated lymphocytes. The early increase in cellular pteridines and their differential release may well provide the basis for their modulating effect on interleukin-2 activity (Ziegler I, et al: Lymphokine Research 3:284, 1984).

Animals↗