Pimenta P F, Saraiva E M, Sacks D L
Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892.
Exp Parasitol. 1991 Feb;72(2):191-204. doi: 10.1016/0014-4894(91)90137-l.
The cellular ultrastructure and surface glycoconjugate expression of three life stages of Leishmania major were compared. Noninfective logarithmic phase promastigotes (LP) are immature cells bearing a thin cell coat, short flagellum, small and empty flagellar pocket, and a loose cytoplasm filled with profiles of ER and large Golgi complex. LP also contain subpopulations of maturing cells containing less ER and Golgi and synthesizing cytoplasmic granules of different size, number, and electron-density. Infective or metacyclic promastigotes (MP) are fully differentiated nondividing forms with a thickened, prominent cell coat, long flagellum, distended flagellar pocket filled with secretory material, and few cytoplasmic organelles other than abundant electron-dense granules. Tissue amastigotes also contain electron-dense cytoplasmic granules, their flagellar pockets are also enlarged and contain secretory material, but they lack a discernable cell coat. Immunogold labeling of GP63 on the cell surface was extensive only on amastigotes. Promastigote GP63 appeared to be masked by the presence of a densely packed lipophosphoglycan (LPG) coat which was extensively labeled on the entire surface of MP and LP. An elongated, developmentally modified form of LPG was abundantly labeled only on MP. LPG was poorly labeled on amastigotes, arguing that the promastigote cell coat is a stage-specific structure which is lost during intracellular transformation.
对硕大利什曼原虫三个生命阶段的细胞超微结构和表面糖缀合物表达进行了比较。非感染性对数期前鞭毛体（LP）是未成熟细胞，具有薄的细胞被膜、短鞭毛、小而空的鞭毛囊以及充满内质网轮廓和大型高尔基体复合体的疏松细胞质。LP还包含成熟细胞亚群，这些细胞含有较少的内质网和高尔基体，并合成大小、数量和电子密度不同的细胞质颗粒。感染性或循环后期前鞭毛体（MP）是完全分化的非分裂形式，具有增厚、突出的细胞被膜、长鞭毛、充满分泌物质的扩张鞭毛囊，除了丰富的电子致密颗粒外几乎没有细胞质细胞器。组织内无鞭毛体也含有电子致密的细胞质颗粒，它们的鞭毛囊也扩大并含有分泌物质，但它们没有可辨认的细胞被膜。细胞表面GP63的免疫金标记仅在无鞭毛体上广泛存在。前鞭毛体GP63似乎被密集堆积的脂磷壁酸（LPG）被膜所掩盖，LPG被膜在MP和LP的整个表面都被广泛标记。一种细长的、发育修饰形式的LPG仅在MP上被大量标记。LPG在无鞭毛体上标记较差，这表明前鞭毛体细胞被膜是一种阶段特异性结构，在细胞内转化过程中会丢失。
