Yoshikawa H, Furuki J, Takahashi Y, Morioka H, Yoshida Y
Department of Biology, Nara Women's University, Japan.
J Electron Microsc (Tokyo). 1992 Oct;41(5):364-8.
The polyene antibiotic, filipin, was used as a probe for demonstrating sterols in the plasma membrane of Trypanosoma brucei gambiense. Three different regions of the continuous plasma membrane over the cell body proper, flagellar pocket, and flagellum, were compared as to density and distribution of the filipin-sterol complexes by freeze-fracture method. The density of the complexes was highest in the cell body membrane and lowest over the flagellar pocket. The filipin-sterol complexes in the cell body membrane were distributed homogeneously on both the protoplasmic and exoplasmic faces except in the zone of flagellar attachment. This junctional zone showed a linear, complex-poor region. In the flagellar membranes, a line of complex-poor regions was observed along the juncture of the flagellum to the cell body. At the neck of the flagellar pocket, the membranes of the flagellar pocket and flagellum were closely opposed, with few filipin-sterol complexes on either membrane. At the base of the flagellar shaft, the complexes were completely lacking on both faces. Based on these observations, the zones of juncture observed in T.b. gambiense seems to be similar in ultrastructure to mammalian cell junctions, such as tight, gap, septate junctions and desmosomes, which show a nearly complete absence of the filipin-sterol complexes.
多烯抗生素制霉菌素被用作探针，以证明布氏冈比亚锥虫质膜中的固醇。通过冷冻断裂法，比较了细胞体本身、鞭毛囊和鞭毛上连续质膜的三个不同区域中制霉菌素 - 固醇复合物的密度和分布。复合物的密度在细胞体膜中最高，在鞭毛囊上最低。细胞体膜中的制霉菌素 - 固醇复合物在原生质面和外质面上均匀分布，除了鞭毛附着区域。这个连接区域显示出一个线性的、复合物较少的区域。在鞭毛膜中，沿着鞭毛与细胞体的连接处观察到一条复合物较少的区域线。在鞭毛囊的颈部，鞭毛囊和鞭毛的膜紧密相对，两个膜上的制霉菌素 - 固醇复合物都很少。在鞭毛轴的基部，两个面上都完全没有复合物。基于这些观察结果，在布氏冈比亚锥虫中观察到的连接区域在超微结构上似乎与哺乳动物细胞连接相似，如紧密连接、间隙连接、分隔连接和桥粒，这些连接显示出几乎完全没有制霉菌素 - 固醇复合物。
