title: Effects of tricyclazole (5-methyl-1,2,4-triazol[3,4] benzothiazole), a specific DHN-melanin inhibitor, on the morphology of Fonsecaea pedrosoi conidia and sclerotic cells.
abstract: The influence of tricyclazole (5-methyl-1,2,4-triazol[3,4]benzothiazole), a specific DHN-melanin inhibitor, on the cell walls and intracellular structures of Fonsecaea pedrosoi conidia and sclerotic cells was analyzed by transmission electron microscopy (TEM), deep-etching, and field emission scanning electron microscopy. The treatment of the fungus with 16 microg mL(-1) of tricyclazole (TC) did not significantly affect fungal viability, but electron microscopy observations showed several important morphological differences between TC-treated and non-TC treated cells. Control sclerotic cells presented patched granules, with an average diameter of 47 nm, on the cell surface, which were absent in TC-treated cells. Also, TC-treated sclerotic cells showed an undulated relief. TC treatment leads to an accumulation of electron lucent vacuoles in the fungal cytoplasm of both conidia and sclerotic cells, and treated conidia observed by deep etching showed a relevant thickening of the fungal cell wall. Together, these observations support the previous data of our group that F. pedrosoi synthesizes melanin in intracellular organelles. In addition, we suggest that melanin is not only an extracellular constituent but could also be dispersing all over the cell walls and could have an effective role in cross-linking different cell wall compounds that help maintain the regular shape of the cell wall.
authors.affiliation: Laboratório de Biologia Celular de Fungos, Instituto de Biofísica Carlos Chagas Filho (IBCCF), Centro de Ciências da Saúde (CCS), Universidade Federal do Rio de Janeiro (UFRJ), Bloco G, Ilha do Fundão, Rio de Janeiro, RJ, 21949-900, Brazil.
authors.forename: Anderson J
authors.initials: AJ
authors.lastname: Franzen
authors.forename: Marcel M L
authors.initials: MM
authors.lastname: Cunha
authors.forename: Evander J O
authors.initials: EJ
authors.lastname: Batista
authors.forename: Sergio H
authors.initials: SH
authors.lastname: Seabra
authors.forename: Wanderley
authors.initials: W
authors.lastname: De Souza
authors.forename: Sonia
authors.initials: S
authors.lastname: Rozental
mesh_terms: D001203:Ascomycota / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure*; D052160:Benzothiazoles / Q000494:pharmacology*; D002473:Cell Wall / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure*; D006801:Humans; D008543:Melanins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D046529:Microscopy, Electron, Transmission
chemical_list: C515168:5-methyl-1,2,4-triazol(3,4)benzothiazole; D052160:Benzothiazoles; D008543:Melanins