Melanins
Mostrando 13-24 de 32 artigos, teses e dissertações.
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13. Anatomical localisation of neuromelanin in the brains of the frog and tadpole. Ultrastructural comparison of neuromelanin with other melanins*
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14. Pathogenic Roles for Fungal Melanins
Melanins represent virulence factors for several pathogenic fungi; the number of examples is growing. Thus, albino mutants of several genera (in one case, mutated precisely in the melanizing enzyme) exhibit decreased virulence in mice. We consider the phenomenon in relation to known chemical properties of melanin, beginning with biosynthesis from ortho-hydro
American Society for Microbiology.
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15. Novel free radicals in synthetic and natural pheomelanins: distinction between dopa melanins and cysteinyldopa melanins by ESR spectroscopy.
Synthetic pheomelanins from enzymic oxidation of the 3,4-dihydroxyphenylalanine (dopa) derivative 5-S-cysteinyldopa have been examined by ESR spectroscopy. These alkalisoluble polymers contain a novel kind of free radical that is spectroscopically distinct from that found in eumelanins. Delocalization of the unpaired electron onto a nitrogen atom and the abi
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16. Melanins and Resistance of Fungi to Lysis
Hyphal walls of Aspergillus phoenicis and Sclerotium rolfsii are composed of large amounts of glucose- and N-acetylhexosamine-containing polysaccharides, and the walls are extensively digested by streptomycete culture filtrates or by a mixture of purified chitinase and β-(1 → 3) glucanase preparations with the release of the monomeric units. A. phoenicis
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17. Biodegradation of 14C-Labeled Model and Cornstalk Lignins, Phenols, Model Phenolase Humic Polymers, and Fungal Melanins as Influenced by a Readily Available Carbon Source and Soil
After 6 months of incubation in a fertile neutral sandy loam, about 48% of the ring carbons and 2-carbons and 60% of the OCH3 carbons of specifically labeled coniferyl alcohol had evolved as CO2. After 1 year, corresponding values were 55 and 65%. When coniferyl alcohol units were linked into model and cornstalk lignins, about 23% of the ring carbons and 2-c
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18. Polymer production by Klebsiella pneumoniae 4-hydroxyphenylacetic acid hydroxylase genes cloned in Escherichia coli.
The expression of Klebsiella pneumoniae hpaA and hpaH genes, which code for 4-hydroxyphenylacetic acid hydroxylase in Escherichia coli K-12 derivative strains, is associated with the production of a dark brown pigment in the cultures. This pigment has been identified as a polymer which shows several of the characteristics reported for microbial melanins and
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19. Melanization of Cryptococcus neoformans in Murine Infection
Cryptococcus neoformans is a fungus that is pathogenic in humans and that can produce melanin in vitro. Melanization is associated with virulence, but there is no evidence that melanin is made during infection. Melanins are difficult to study because they are amorphous and insoluble. Melanin-binding peptides from a phage display library were used to demonstr
American Society for Microbiology.
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20. Upper boundary of the biosphere.
By using meterological rockets fitted with specially designed analyzers, samples for microbiological investigation have been taken. The analyzer design prevented extraneous microorganisms from penetrating into the analyzer. Before being used, the analyzers were sterilized with high gamma-ray doses. For the first time microorganisms have been detected in the
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21. Inhibition of the Lysis of Fungi by Melanins
Evidence is presented that the resistance of Aspergillus nidulans hyphae to lysis by a β-(1→3) glucanase-chitinase mixture results from the presence of melanin in the fungal walls. The resistance of the walls to digestion was directly correlated with the melanin content of the mycelium. A melanin-less mutant of A. nidulans was highly susceptible to hydrol
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22. Degradation of melanin by Aspergillus fumigatus.
A strain of Aspergillus fumigatus from composted coffee and garden wastes utilized natural deproteinized insect, banana, hair, octopus, and synthetic tyrosine and dopa melanins as sole sources of carbon. With a sucrose supplement, degradation was essentially complete after 50 days in Czapek medium pH 6.5 at 30 degrees C. The catabolic rate differed for each
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23. Scytalidium dimidiatum Causing Recalcitrant Subcutaneous Lesions Produces Melanin
Scytalidium dimidiatum is a pigmented dematiaceous coelomycete that typically causes chronic superficial skin diseases and onychomycosis, as well as deeper infections, such as subcutaneous abscesses, mycetoma, and even fungemia in immunocompromised patients. A second species, Scytalidium hyalinum, has hyaline hyphae and arthroconidia and is considered by som
American Society for Microbiology.
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24. Population Genetics of LEBISTES (POECILIA) RETICULATUS Peters (Poeciliidae; Pisces). I. Effects of Radiation-Induced Mutations on the Segregation Ratio in Postirradiation F2
Wild-type germ cells of the viviparous fish, Lebistes (Poecilia) reticulatus, were irradiated in the stages of oogonia, spermatogonia or spermatozoa with 1000 R of X rays at a dose-rate of 200–220 R/min. The grown-up fish were mated after irradiation or sham treatment to unirradiated mutant fish homozygous for three recessive gene loci, causing albinism, l