title: Comparative analysis of Cryptococcus neoformans acid-resistant particles generated from pigmented cells grown in different laccase substrates.
abstract: Cryptococcus neoformans produces pigments in vitro in the presence of exogenous substrate. We characterized acid-resistant particles isolated from pigmented cells grown in L-dopa, methyl-dopa, (-)-epinephrine or (-)-norepinephrine. The goals of this study were to determine whether pigments made from each of these substrates were melanins and the consequences of pigmentation on related cell characteristics. The greatest yield of acid-resistant particles occurred with methyl-dopa followed by L-dopa. Electron microscopy indicated that L-dopa and methyl-dopa produced particles with thicker shells. The mAb 6D2 reacted with all particles, but a lower reactivity was observed with epinephrine-derived particles. ESR analysis revealed that epinephrine-derived particles failed to produce a stable free radical signal typical of melanins. Growth of C. neoformans in different substrates affected cell and capsule size but not capsule induction. Hence, the type of pigment produced by C. neoformans is dependent on the substrate and not all pigments meet the criteria for melanins.
authors.affiliation: Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
authors.forename: Javier
authors.initials: J
authors.lastname: Garcia-Rivera
authors.forename: Helene C
authors.initials: HC
authors.lastname: Eisenman
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Nosanchuk
authors.forename: Philip
authors.initials: P
authors.lastname: Aisen
authors.forename: Oscar
authors.initials: O
authors.lastname: Zaragoza
authors.forename: Tiffany
authors.initials: T
authors.lastname: Moadel
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Dadachova
authors.forename: Arturo
authors.initials: A
authors.lastname: Casadevall
mesh_terms: D002851:Chromatography, High Pressure Liquid; D003455:Cryptococcus neoformans / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D003594:Cytoplasmic Granules / Q000737:chemistry* / Q000648:ultrastructure; D004578:Electron Spin Resonance Spectroscopy; D004837:Epinephrine / Q000378:metabolism; D007980:Levodopa / Q000378:metabolism; D008543:Melanins / Q000096:biosynthesis / Q000737:chemistry; D008750:Methyldopa / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D009638:Norepinephrine / Q000378:metabolism; D015388:Organelles / Q000648:ultrastructure; D010860:Pigments, Biological / Q000096:biosynthesis* / Q000737:chemistry
chemical_list: D008543:Melanins; D010860:Pigments, Biological; D007980:Levodopa; D008750:Methyldopa; D009638:Norepinephrine; D004837:Epinephrine