title: L-DOPA accessibility in culture medium increases melanin expression and virulence of Sporothrix schenckii yeast cells.
abstract: Melanin is a complex polymer widely distributed in nature and has been described as an important virulence factor in several pathogenic fungi, including Sporothrix schenckii. The aim of the present work was to investigate the presence of melanin on the surface of S. schenckii yeast cells which showed differences in their virulence depending on the culture conditions under which they were grown. Yeast cells were cultivated in brain heart infusion (BHI) broth from Difco and Oxoid. BHI from these two vendors are different in their brain and heart infusion contents. Yeasts cultivated in the medium containing the higher brain infusion content were highly virulent as ascertained by the mice mortality rate, CFU and histopathology. Transmission electron microscopy revealed a higher expression of electron dense granules on the fungal cell wall of the most virulent yeast cells. Flow cytometry analysis, with anti-melanin antibodies, confirmed that this pigment was melanin. Furthermore, spectrophotometric analysis showed a higher concentration of this polymer on NaOH and cell wall extracts of the most virulent yeast cells. These results suggest that differences in the relative content of brain and heart infusion in the culture medium modulated melanin expression on the surface of S. schenckii yeast cells and, as a consequence, virulence. A new pathway of melanin biosynthesis in S. schenckii is proposed which involves the use of phenolic compounds from rich brain medium as melanin substrate.
authors.affiliation: Departamento de Biologia Celular, Instituto de Biologia Roberto Alcantara Gomes, Universidade do Estado do Rio de Janeiro, Brasil.
authors.forename: Pedro Antônio Castelo
authors.initials: PA
authors.lastname: Teixeira
authors.forename: Rafaela Alves
authors.initials: RA
authors.lastname: De Castro
authors.forename: Fernanda Rodrigues Lanzana
authors.initials: FR
authors.lastname: Ferreira
authors.forename: Marcel M Lyra
authors.initials: MM
authors.lastname: Cunha
authors.forename: Armando Pérez
authors.initials: AP
authors.lastname: Torres
authors.forename: Carla Verônica Loureiro Y
authors.initials: CV
authors.lastname: Penha
authors.forename: Sonia
authors.initials: S
authors.lastname: Rozental
authors.forename: Leila M
authors.initials: LM
authors.lastname: Lopes-Bezerra
mesh_terms: D000818:Animals; D015169:Colony Count, Microbial; D003470:Culture Media / Q000737:chemistry; D004195:Disease Models, Animal; D006651:Histocytochemistry; D007980:Levodopa / Q000378:metabolism*; D008099:Liver / Q000382:microbiology; D008168:Lung / Q000382:microbiology; D008297:Male; D008543:Melanins / Q000096:biosynthesis*; D051379:Mice; D008810:Mice, Inbred C57BL; D008853:Microscopy; D013154:Spleen / Q000382:microbiology; D013175:Sporothrix / Q000378:metabolism* / Q000472:pathogenicity*; D013174:Sporotrichosis / Q000382:microbiology / Q000473:pathology; D016019:Survival Analysis; D014774:Virulence
chemical_list: D003470:Culture Media; D008543:Melanins; D007980:Levodopa