Laboratório de Helmintologia Romero Lascasas Porto, Universidade do Estado do Rio de Janeiro, Departamento de Microbiologia, Imunologia e Parasitologia, Brazil.
Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, RJ, Brazil.
J Struct Biol. 2020 Nov 1;212(2):107611. doi: 10.1016/j.jsb.2020.107611. Epub 2020 Sep 3.
Whipworms of the genus Trichuris are nematode parasites that infect mammals and can lead to various intestinal diseases of human and veterinary interest. The most intimate interaction between the parasite and the host intestine occurs through the anterior region of the nematode body, inserted into the intestinal mucosa during infection. One of the most prominent structures of the nematode surface found at the infection site is the bacillary band, a surface domain formed by a number of cells, mostly stichocytes and bacillary glands, whose structure and function are still under debate. Here, we used confocal microscopy, field emission scanning electron microscopy, helium ion microscopy, transmission electron microscopy and FIB-SEM tomography to unveil the functional role of the bacillary gland cell. We analyzed the surface organization as well as the intracellular milieu of the bacillary glands of Trichuris muris in high pressure frozen/freeze-substituted samples. Results showed that the secretory content is preserved in all gland openings, presenting a projected pattern. FIB-SEM analysis showed that the lamellar zone within the bacillary gland chamber is formed by a set of lacunar structures that may exhibit secretory or absorptive functions. In addition, incubation of parasites with the fluid phase endocytosis marker sulforhodamine B showed a time-dependent uptake by the parasite mouth, followed by perfusion through different tissues with ultimate secretion through the bacillary gland. Taken together, the results show that the bacillary gland possess structural characteristics of secretory and absorptive cells and unequivocally demonstrate that the bacillary gland cell functions as a secretory structure.
旋毛虫属的鞭虫是一种寄生在哺乳动物体内的线虫寄生虫，可导致人类和兽医关注的各种肠道疾病。寄生虫与宿主肠道之间最密切的相互作用发生在线虫体的前区，在感染过程中插入肠黏膜。在感染部位发现的线虫表面最突出的结构之一是杆菌带，这是一个由许多细胞形成的表面结构域，主要是刺细胞和杆菌腺，其结构和功能仍存在争议。在这里，我们使用共聚焦显微镜、场发射扫描电子显微镜、氦离子显微镜、透射电子显微镜和 FIB-SEM 断层扫描技术，揭示了杆菌腺细胞的功能作用。我们分析了高压冷冻/冷冻置换样品中旋毛虫杆菌腺的表面组织以及细胞内环境。结果表明，所有腺开口处都保留了分泌内容物，呈现出突出的模式。FIB-SEM 分析表明，杆菌腺腔内的层状区由一组腔隙结构组成，这些结构可能具有分泌或吸收功能。此外，用液相反噬标记物磺基罗丹明 B 孵育寄生虫显示寄生虫口的时间依赖性摄取，随后通过不同组织进行灌注，最终通过杆菌腺分泌。综上所述，结果表明杆菌腺具有分泌细胞和吸收细胞的结构特征，并明确证明杆菌腺细胞是一种分泌结构。
