Ganser Maximilian H, Bartel Heidi, Weißenbacher Birgit, Andosch Ancuela, Lütz-Meindl Ursula, Radacher Peter, Agatha Sabine
Department of Environment & Biodiversity, Paris Lodron University of Salzburg, Hellbrunnerstraße 34, 5020 Salzburg, Austria.
Department of Environment & Biodiversity, Paris Lodron University of Salzburg, Hellbrunnerstraße 34, 5020 Salzburg, Austria.
Eur J Protistol. 2022 Oct;86:125922. doi: 10.1016/j.ejop.2022.125922. Epub 2022 Sep 6.
Resting cysts protect ciliates against adverse environmental conditions. The morphology and ultrastructure of resting cysts has been described in very few Oligotrichea, a group of mainly marine planktonic ciliates. The present study provides the first ultrastructural data for loricate choreotrichids, applying light and electron microscopy on the cysts of the tintinnid Schmidingerella meunieri (Kofoid and Campbell, 1929) Agatha and Strüder-Kypke, 2012. The morphology of live cysts and the wall ultrastructure of cryofixed cysts were morphometrically analysed. The resting cyst is roughly flask-shaped, broadening to a slightly concave, laterally protruding anterior plate. An emergence pore closed by a skull cap-shaped papula is directed to the bottom of the lorica on the opposite side of the cyst. The cyst wall consists of an ectocyst, mesocyst, and endocyst differing in thickness, structure, and nitrogen concentration as revealed by conventional transmission electron microscopy, electron energy loss spectroscopy, and electron spectroscopic imaging. The cysts of S. meunieri belong to the kinetosome-resorbing type, which also occurs in the majority of hypotrich ciliates. Two main features (flask-shape and presence of an emergence pore) are shared with the closely related aloricate choreotrichids and oligotrichids, distinguishing the Oligotrichea from the hypotrich and the more distantly related euplotid ciliates.
休眠包囊可保护纤毛虫抵御不利的环境条件。在寡毛目（一类主要为海洋浮游纤毛虫）中，仅有极少数种类的休眠包囊的形态和超微结构得到过描述。本研究利用光学显微镜和电子显微镜，对钟形虫Schmidingerella meunieri（Kofoid和Campbell，1929）Agatha和Strüder-Kypke，2012的包囊进行观察，首次提供了有鞘缘毛类纤毛虫的超微结构数据。对活包囊的形态以及冷冻固定包囊的壁超微结构进行了形态测量分析。休眠包囊大致呈烧瓶状，向一个略凹陷、侧向突出的前板扩展。一个由帽状丘疹封闭的出孔朝向包囊相对一侧的鞘的底部。通过传统透射电子显微镜、电子能量损失谱和电子光谱成像揭示，包囊壁由外囊、中囊和内囊组成，它们在厚度、结构和氮浓度上存在差异。S. meunieri的包囊属于动基体吸收型，大多数下毛类纤毛虫也具有这种类型。两个主要特征（烧瓶形状和存在出孔）与亲缘关系密切的无鞘缘毛类纤毛虫和寡毛类纤毛虫相同，这使寡毛目与下毛类以及亲缘关系更远的真鞘类纤毛虫区分开来。
