Origin of phagocytosis in eukaryotic cells

真核细胞是真细菌在古细菌宿主细胞内形成细胞器而形成的。 虽然真核细胞具有真核生物所特有的特征，但这些独特特征的起源尚未阐明。 系统发育分析表明，吞噬作用的起源与古细菌中发现的细胞骨架同源物有关。 然而，在原核细胞中从未发现吞噬作用。 我们最近观察到的特点表明可能的吞噬作用的古菌嗜酸热浆菌的细胞结构。 在这项工作中，我们已经构建了三维结构的细胞从连续显微照片的切片，并分析了结构与共聚焦激光显微镜，这表明在古细菌的吞噬作用。

Eukaryotic cell has been originated by the endosymbiosis of eubacteria forming organelle in an archaebacterial host cell. Though the eukaryotic cells have characteristics unique to eukaryotes, the origin of these unique characteristics has not been elucidated. Phylogenetic analysis revealed that the origin of the phagocytosis is related to the homolog of cytoskeleton found in archaebacteria. However, phagocytosis has never been found in prokaryotic cells. We have recently observed the characteristics suggesting the possible phagocytosis in cellular structure of an archaeon Thermoplasma acidophilum. In this work we have constructed 3D structures of the cells from continuous micrographs of ultrathin sections and analyzed the structure with confocal laser microscope, suggesting the phagocytosis in the archaeon.