Cunha Marcel M L, Franzen Anderson J, Alviano Daniela S, Zanardi Erica, Alviano Celuta S, De Souza Wanderley, Rozental Sonia
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 21949-900, Brazil.
Microsc Res Tech. 2005 Dec 15;68(6):377-84. doi: 10.1002/jemt.20260.
Fonsecaea pedrosoi produces melanin, a pigment related to virulence in pathogenic fungi. To understand the involvement of melanin in the protection of fungi, the authors used tricyclazole to inhibit the melanin pathway in F. pedrosoi. Experiments of pigmentation suggested that F. pedrosoi uniquely produces dihydroxynaphthalene-melanin. Pigments produced on cultures modified or not with tricyclazole were extracted by an alkali-acid method and submitted to infrared and ion exchange chromatography analysis; also cytochemistry analysis for cationized ferritin of whole cells was carried out. This group of experiments showed that the tricyclazole treatment on F. pedrosoi produced a melanin-like pigment, but less negatively charged and with less affinity for iron ions than that without the tricyclazole treatment, and this in turn lead to a less negatively charge cell wall surface. Scanning electron microscopy of such pigments showed that the melanin from control cultures maintained their hyphae-like structures, which have been described as "melanin-ghosts," whereas the tricyclazole pigment showed an amorphous surface. Interaction of conidia from cultures of F. pedrosoi, modified by tricyclazole or not, with peritoneal activated macrophages suggested that tricyclazole causes higher association of fungus with macrophages, weakens the fungus capacity to destroy the macrophages, and diminishes the resistance to dry fracture procedures on samples prepared for high resolution scanning electron microscopy.
佩德罗索分支孢菌能产生黑色素，这种色素与致病真菌的毒力有关。为了解黑色素在真菌保护中的作用，作者使用三环唑抑制佩德罗索分支孢菌中的黑色素合成途径。色素沉着实验表明，佩德罗索分支孢菌独特地产生二羟基萘黑色素。用酸碱法提取经三环唑处理或未处理的培养基上产生的色素，并进行红外和离子交换色谱分析；还对全细胞阳离子铁蛋白进行了细胞化学分析。这组实验表明，三环唑处理佩德罗索分支孢菌产生了一种类似黑色素的色素，但与未经三环唑处理的色素相比，其带负电荷较少，对铁离子的亲和力较低，这反过来导致细胞壁表面带负电荷较少。对此类色素的扫描电子显微镜观察表明，对照培养基中的黑色素保持其菌丝样结构，这种结构被描述为“黑色素幽灵”，而三环唑色素则呈现无定形表面。用三环唑处理或未处理的佩德罗索分支孢菌培养物的分生孢子与腹膜活化巨噬细胞的相互作用表明，三环唑导致真菌与巨噬细胞的结合增加，削弱真菌破坏巨噬细胞的能力，并降低为高分辨率扫描电子显微镜制备的样品对干断裂程序的抵抗力。
