Ultrastructural characterization of melanosomes of the human pathogenic fungus Fonsecaea pedrosoi
Ultrastructural characterization of melanosomes of the human pathogenic fungus Fonsecaea pedrosoi
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DOI：
10.1016/j.jsb.2007.11.004
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发表时间：
2008-04-01
影响因子：
3
通讯作者：
Rozental, Sonia
中科院分区：
文献类型：
--
作者：
Franzen, Anderson J.;Cunha, Marcel M. L.;Rozental, Sonia
黑色素是一种广泛存在于自然界的复杂聚合物，是致病真菌的重要毒力因子。在大多数真菌中，黑色素形成的机制尚不清楚。在嗜色细胞菌病的主要病原——红毛菌中，黑色素储存在称为黑素体的细胞内囊泡中。本文详细介绍了人致病性真菌黑素的形成、储存和细胞壁转运的超微结构方面的情况。在这种真菌中，黑色素小体内的黑色素合成也开始于纤维基质的形成，表现出与两栖动物和哺乳动物细胞中的黑色素小体相似的形态和结构特征。基于丰塔纳-马森法检测黑色素和免疫细胞化学的银沉淀表明，黑色素小体与真菌细胞膜融合，黑色素释放并到达细胞壁。黑色素在真菌细胞壁上呈同心层状沉积。抗黑素E的抗体揭示了黑素小体中黑色素产生和储存的位点。此外，通过x射线微分析和元素作图对该细胞器的元素组成进行了初步描述，发现其基质中存在钙、磷和铁的富集，提示这些细胞器可能具有作为铁储存室的新功能。(C) 2007爱思唯尔公司版权所有。
Melanin is a complex polymer widely distributed in nature and has been described as an important virulence factor in pathogenic fungi. In the majority of fungi, the mechanism of melanin formation remains unclear. In Fonsecaea pedrosoi, the major etiologic agent of chromoblastomycosis, melanin is stored in intracellular vesicles, named melanosomes. This paper details the ultrastructural aspects of melanin formation, its storage and transportation to the cell wall in the human pathogenic fungus F pedrosoi. In this fungus, melanin synthesis within melanosomes also begins with a fibrillar matrix formation, displaying morphological and structural features similar to melanosomes from amphibian and mammalian cells. Silver precipitation based on Fontana-Masson technique for melanin detection and immunocytochemistry showed that melanosome fuses with fungal cell membrane where the melanin is released and reaches the cell wall. Melanin deposition in the fungal cell wall occurs in concentric layers. Antibodies raised against E pedrosoi melanin revealed the sites of melanin production and storage in the melanosomes. In addition, a preliminary description of the elemental composition of this organelle by X-ray microanalysis and elemental mapping revealed the presence of calcium, phosphorus and iron concentrated in its matrix, suggesting a new functional role for these organelles as iron storage compartments. (C) 2007 Elsevier Inc. All rights reserved.