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Previous issue date: 2010-02-26 / Paracoccidioides brasiliensis is a thermo-dimorphic human pathogenic fungus
that lives at 23”C in the mycelium phase (infecting phase) and at 37”C in the yeast
phase (parasite phase). In attempt to survive, the cell wall of fungi can change its
composition and/or structure in response to environmental stress by compensatory
mechanisms. The molecules involved in these mechanisms are possible target for the
development of effective antifungal agents. In P. brasiliensis, the main components of
the cell wall are glucans and chitin polymers. These polymers make a primary barrier
that is responsible for the structural integrity and form of the cell wall. In this work the
behavior of P. brasiliensis was evaluated against stress conditions with the aim of study,
for the first time, the mechanisms used by this fungus in the maintenance of the cell
wall integrity. Our results shown that P. brasiliensis yeast cells are sensitive to cell wall
stressors calcofluor white (CFW), congo red (CR), SDS, KCl, NaCl and sorbitol. There
was an increase in the PbFKS1 transcripts expression and in the content of cell wall β-
1,3-glicana after treatment with all stressor agents. After treatment with SDS and KCl
the PbGFA1 transcripts expression and the cell wall GlcNAc residues also increased.
The transcript expression of PbGEL3 was also evaluated being increased after treatment
with CFW, NaCl and sorbitol. Thus we showed that these molecules are involved in the
maintenance of the cell wall against stress conditions. Apart from these analyses we
obtained the active recombinant protein PbFks1pc. Through the anti-PbFks1pc antibody
we performed immunocitolocalization assays. These experiments revealed the
localization of PbFks1p in regions of apical growth in the mycelium phase and in the
cell surface in yeast phase. / Paracoccidioides brasiliensis Š um fungo patog‰nico e termodim‚rfico que se
apresenta na forma de micŠlio a 23”C (forma infectante) e na forma de levedura a 37”C
(forma parasit€ria). A parede celular de fungos Š capaz de alterar sua composiƒ o e atŠ
mesmo sua estrutura em resposta a condiƒ•es ambientais de estresse atravŠs de
mecanismos compensat‚rios. As prote…nas envolvidas nestes mecanismos s o poss…veis
alvos para o desenvolvimento de agentes antifˆngicos espec…ficos. Em P. brasiliensis,
os principais pol…meros que constituem a parede celular s o glicanas e quitina. Estes
pol…meros formam uma barreira prim€ria que Š respons€vel pela integridade estrutural e
forma da parede celular. Neste trabalho, o comportamento de P. brasiliensis diante de
situaĥes de estresse foi investigado com o intuito de estudar, pela primeira vez, os
mecanismos utilizados por este fungo na manutenƒ o da integridade da parede celular.
Nossos resultados mostram que cŠlulas leveduriformes de P. brasiliensis s o sens…veis
aos agentes estressores da parede celular calcofluor white (CFW), congo red (CR), SDS,
NaCl, KCl e sorbitol. Houve um aumento na express o de transcritos de PbFKS1 e no
conteˆdo do pol…mero de β-1,3-glicana na parede celular ap‚s tratamento com todos os
agentes estressores. Ap‚s tratamento com SDS e KCl a express o de transcritos de
PbGFA1 assim como o conteˆdo de res…duos de GlcNAc na parede celular tambŠm
aumentaram. A express o dos transcritos de PbGEL3 tambŠm foi avaliada estando
aumentada ap‚s tratamento com CFW, NaCl e sorbitol. Desta forma, mostramos que
estas molŠculas est o envolvidas na manutenƒ o da parede celular diante de situaƒ•es
de estresse. AlŠm destas an€lises, a prote…na recombinante PbFks1pc ativa foi obtida.
AtravŠs do anticorpo anti-PbFks1pc realizamos ensaios de imunocitolocalizaƒ o. Estes
experimentos revelaram a presenƒa de PbFks1p em regi•es de crescimento apical no
micŠlio e na superf…cie celular em cŠlulas leveduriformes.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.bc.ufg.br:tde/1501 |
| Date | 26 February 2010 |
| Creators | TOMAZETT, Patrícia Kott |
| Contributors | PEREIRA, Maristela |
| Publisher | Universidade Federal de Goiás, Doutorado em Ciencias da Saude, UFG, BR, Ciencias da Saude |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da UFG, instname:Universidade Federal de Goiás, instacron:UFG |
| Rights | info:eu-repo/semantics/openAccess |
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