Detection of Melanin-Like Pigments in the Dimorphic Fungal Pathogen<i>Paracoccidioides brasiliensis</i>In Vitro and during Infection

Gómez, Beatriz L.; Nosanchuk, Joshua D.; Dı́ez, Soraya; Youngchim, Sirida; Aisen, Philip; Cano, Luz Elena; Restrepo, Ángela; Casadevall, Arturo; Hamilton, Andrew J.

doi:10.1128/iai.69.9.5760-5767.2001

Cited by 112 publications

(121 citation statements)

References 45 publications

(37 reference statements)

Supporting

Mentioning

104

Contrasting

Unclassified

Order By: Relevance

“…The ability of P. brasiliensis to make melanin pigments was first described by Gómez et al [15] (Fig. 1).…”

Section: Paracoccidioides Brasiliensismentioning

confidence: 99%

“…A laccase-like activity was detected in protein extracts of P. brasiliensis that was implicated in the enzymatic synthesis of melanin in yeast cells. Additionally, in vitro conidial melanization is quite significant since conidia become pigmented when suspended in pure water indicating a capacity to synthesize melanin-like pigment in the absence of L-DOPA, which would require the fungus to either synthesize its own phenolic precursors for use via laccase or to utilize a different mechanism, such as the polyketide synthesis pathway, to produce melanin [15].…”

Section: Paracoccidioides Brasiliensismentioning

confidence: 99%

“…The synthesis of melanin in fungi by the DOPA-melanin pathway, also known as eumelanin, requires the presence of exogenous substrate in the form of certain o-diphenolic and p-diphenolic compounds, such as 3,4 dihydroxyphenylalanine (L-DOPA) [11]. The pathogenic fungi investigated in the production of DOPA-melanins via polyphenoloxidase (a laccase) include many model organisms such as Cryptococcus neoformans [12,13], Paracoccidioides brasiliensis [14,15], Histoplasma capsulatum [16], Blastomyces dermatitidis [17], Candida albicans [18], and Coccidioides posadasii [19].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Melanin as a virulence factor of Paracoccidioides brasiliensis and other dimorphic pathogenic fungi: a minireview

et al. 2008

Self Cite

View full text Add to dashboard Cite

Melanin pigments are substances produced by a broad variety of pathogenic microorganisms, including bacteria, fungi, and helminths. Microbes predominantly produce melanin pigment via tyrosinases, laccases, catecholases, and the polyketide synthase pathway. In fungi, melanin is deposited in the cell wall and cytoplasm, and melanin particles (''ghosts'') can be isolated from these fungi that have the same size and shape of the original cells. Melanin has been reported in several human pathogenic dimorphic fungi including Paracoccidioides brasiliensis, Sporothrix schenckii, Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides posadasii. Melanization appears to contribute to virulence by reducing the susceptibility of melanized fungi to host defense mechanisms and antifungal drugs.

show abstract

“…The ability of P. brasiliensis to make melanin pigments was first described by Gómez et al [15] (Fig. 1).…”

Section: Paracoccidioides Brasiliensismentioning

confidence: 99%

Section: Paracoccidioides Brasiliensismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Melanin as a virulence factor of Paracoccidioides brasiliensis and other dimorphic pathogenic fungi: a minireview

et al. 2008

Self Cite

View full text Add to dashboard Cite

show abstract

“…The following species were investigated: C. neoformans , Sporothrix schenckii (Romero-Martinez et al 2000), P. brasiliensis (Gomez et al 2001, da Silva et al 2006, Fonsecaea pedrosoi (Alviano et al 2004), Aspergillus fumigatus (Youngchim et al 2004) and C. posadasii (Nosanchuk et al 2007). Generally, a cellular immune response appears to be the most effective defence mechanism against both experimental and human PCM (Calich et al 1994, Marques Mello et al 2002, Batista et al 2005.…”

mentioning

confidence: 99%

Resistance of melanized yeast cells of Paracoccidioides brasiliensis to antimicrobial oxidants and inhibition of phagocytosis using carbohydrates and monoclonal antibody to CD18

Silva

Thomaz

Marques

et al. 2009

Mem. Inst. Oswaldo Cruz

Self Cite

View full text Add to dashboard Cite

“…The debris was collected, washed with PBS and then boiled in 6 M HCl for 1 h. If particles remained, they were collected, washed in PBS and dialysed extensively against distilled water. This procedure has been shown to solubilize non-melanized C. neoformans, Paracoccidioides brasiliensis, S. cerevisiae and Candida albicans yeast cells (Gó mez et al, 2001; Rosas et al, 2000b).Scanning electron microscopy (SEM). The particles isolated from the treated cells were studied by SEM as described previously (Nosanchuk et al, 1999a).…”

mentioning

confidence: 99%

Budding of melanized Cryptococcus neoformans in the presence or absence of l-dopa

Nosanchuk

Casadevall

2003

Microbiology

Self Cite

View full text Add to dashboard Cite

Cryptococcus neoformans is a pathogenic fungus that produces melanin when incubated in the presence of certain phenolic substrates such as L-3,4-dihydroxyphenylalanine (L-dopa). Melanin is an enigmatic polymer that is deposited in the cell wall and contributes to virulence. Substantial progress has been made in understanding the synthesis of melanin and the mechanisms by which it contributes to virulence, but relatively little is known about how melanin is rearranged during growth and budding. In this study we used transmission and scanning electron microscopy and immunofluorescence of melanized cells and melanin 'ghosts' to study the process of melanization during replication. Budding in melanized C. neoformans results in focal disruption of cell-wall melanin at the bud site. In the presence of L-dopa, bud-related melanin defects are repaired and daughter cells are melanized. However, in the absence of substrate, mother cells cannot repair their melanin defects and daughter cells are non-melanized. Hence, melanin in the parent cell is not carried to the daughter cells, but rather is synthesized de novo in buds. These results imply that melanin remodelling occurs during cell growth in a process that involves degradation and synthesis at sites of budding. INTRODUCTIONCryptococcus neoformans is an encapsulated, environmental fungus that can cause life-threatening meningitis, particularly in immunocompromised individuals. The ability of C. neoformans to make melanin was discovered in the early 1960s (Staib, 1962(Staib, , 1963 and was associated with virulence in the 1980s Rhodes et al., 1982). Melanins are rigid, acid-resistant polymers of uncertain structure that are found in all biological kingdoms (Hill, 1992). The synthesis of melanin by C. neoformans occurs only in the presence of phenolic compounds, such as L-3,4-dihydroxyphenylalanine (L-dopa), and is catalysed by a laccase Williamson, 1994). The C. neoformans laccase has recently been shown to be tightly associated with the cell wall by a hydrolysable bond (Zhu et al., 2001). When the fungus grows in the presence of phenolic compounds, melanin is deposited in the cell wall (Wang et al., 1995) and comprises approximately 15 % of the dry weight of late-stationary-phase melanized C. neoformans (Wang & Casadevall, 1996). C. neoformans is melanized in the environment (Nosanchuk et al., 1999b) and during human infection (Nosanchuk et al., 2000). In the environment melanin is thought to protect the fungus against extremes of temperature (Rosas & Casadevall, 1997), ultraviolet light (Wang & Casadevall, 1994a), heavy metals (Garcia-Rivera & Casadevall, 2001) and amoeboid predators (Steenbergen et al., 2001). During infection melanin appears to function in virulence by protecting fungal cells against microbicidal oxidants (Wang & Casadevall, 1994b) and peptides (Doering et al., 1999) produced by immune effector cells. Furthermore, melanin may interfere with the development of effective cellmediated responses (Huffnagle et al., 1995) and could affect the activation ...

show abstract

Detection of Melanin-Like Pigments in the Dimorphic Fungal PathogenParacoccidioides brasiliensisIn Vitro and during Infection

Cited by 112 publications

References 45 publications

Melanin as a virulence factor of Paracoccidioides brasiliensis and other dimorphic pathogenic fungi: a minireview

Melanin as a virulence factor of Paracoccidioides brasiliensis and other dimorphic pathogenic fungi: a minireview

Resistance of melanized yeast cells of Paracoccidioides brasiliensis to antimicrobial oxidants and inhibition of phagocytosis using carbohydrates and monoclonal antibody to CD18

Budding of melanized Cryptococcus neoformans in the presence or absence of l-dopa

Contact Info

Product

Resources

About