Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Instituto Nacional de Ciência e Tecnologia, and Núcleo de Biologia Estrutural e Bioimagens-CENABIO, Universidade Federal do Rio de Janeiro - UFRJ, Rio de Janeiro, Brazil; Fiocruz, Instituto Oswaldo Cruz, Laboratório de Ultraestrutura Celular, Rio de Janeiro, Brazil.
Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Instituto Nacional de Ciência e Tecnologia, and Núcleo de Biologia Estrutural e Bioimagens-CENABIO, Universidade Federal do Rio de Janeiro - UFRJ, Rio de Janeiro, Brazil.
J Struct Biol. 2019 Sep 1;207(3):301-311. doi: 10.1016/j.jsb.2019.07.002. Epub 2019 Jul 2.
Giardia intestinalis presents an intriguing endomembrane system, which includes endoplasmic reticulum and peripheral vesicles (PVs). The PVs have previously been considered to be organelles that display early and late endosomal and lysosomal properties. Some of these vesicles accumulate macromolecules ingested by the protozoan and show acid phosphatase activity. It has been previously shown that the parasite releases microvesicles, which contribute to giardiasis pathogenesis; however, the vesicles' origin and the way in which they are released by the parasite still remain unclear. In this study, we induced the parasites to encyst in vitro and analyzed these events using advanced electron microscopy techniques, including focused ion beam and electron microscopy tomography followed by three-dimensional reconstruction, in order to better understand protozoal multivesicular body (MVB) biogenesis. In addition, we performed an ultrastructural analysis of phosphatase activity during differentiation. We demonstrated that some vegetative trophozoites' PVs exhibited morphological characteristics of MVBs with a mean diameter of 50 nm, containing intraluminal vesicles (ILVs).
肠道贾第虫呈现出一种引人入胜的内膜系统，其中包括内质网和周边囊泡（PVs）。先前认为这些 PVs 是具有早期和晚期内体和溶酶体特性的细胞器。其中一些囊泡积累了原生动物摄取的大分子，并显示酸性磷酸酶活性。先前的研究表明，寄生虫释放微囊泡，有助于贾第虫病的发病机制；然而，这些囊泡的起源以及寄生虫释放它们的方式仍然不清楚。在这项研究中，我们诱导寄生虫在体外形成包囊，并使用先进的电子显微镜技术分析这些事件，包括聚焦离子束和电子显微镜断层扫描，随后进行三维重建，以便更好地了解原生动物多泡体（MVB）的生物发生。此外，我们还在分化过程中进行了磷酸酶活性的超微结构分析。我们证明，一些营养体滋养体的 PVs 表现出具有 50nm 平均直径的 MVB 的形态特征，其中包含腔内囊泡（ILVs）。
