Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
Graduate School of Human and Environmental Studies, Kyoto University, Yoshida, Nihonmatsu-cho, Sakyo-ku, Kyoto 606-8501, Japan.
Protist. 2020 Apr;171(2):125714. doi: 10.1016/j.protis.2020.125714. Epub 2020 Jan 30.
The difficult-to-cultivate katablepharid Hatena arenicola ingests green algae, Nephroselmis spp., and temporarily retains a Nephroselmis-derived cell compartment (kleptochloroplast), including a chloroplast within a phagocytotic vacuole. H. arenicola has a unique life history; during cell division, the Nephroselmis-derived cell compartment is only inherited by one of two daughter cells. However, the detailed morphological transition of the Nephroselmis cell to a kleptochloroplast and the mitotic process of the host cell remain unclear. Herein, we observed feeding behavior, enlargement of the Nephroselmis-derived chloroplast, and mitotic processes in H. arenicola using light and electron microscopy. During feeding behavior, H. arenicola peeled off the cell coverings and flagella of the Nephroselmis cell, which selectively accumulated in a vacuole separate to one containing a Nephroselmis cell body. An obvious nucleolus, but no heterochromatin was observed in the Nephroselmis-derived nucleus during the chloroplast-enlarging process, while compressed heterochromatin was explicitly observed in the nuclei of free-living Nephroselmis cells. The cell membrane of an ingested Nephroselmis cell disintegrated during enlargement of the Nephroselmis-derived chloroplast. The process of mitosis in H. arenicola was very similar to that of other katablepharids and cryptophytes.
难以培养的可食用 Hatena arenicola 摄取绿藻 Nephroselmis spp.，并暂时保留一个源自 Nephroselmis 的细胞隔室（偷食叶绿体），包括一个吞噬泡内的叶绿体。H. arenicola 具有独特的生活史；在细胞分裂过程中，源自 Nephroselmis 的细胞隔室仅由两个子细胞中的一个继承。然而，源自 Nephroselmis 的细胞向偷食叶绿体的详细形态转变以及宿主细胞的有丝分裂过程仍不清楚。在此，我们使用光镜和电子显微镜观察了 H. arenicola 的摄食行为、源自 Nephroselmis 的叶绿体的增大和有丝分裂过程。在摄食行为中，H. arenicola 剥去了 Nephroselmis 细胞的细胞覆盖物和鞭毛，这些物质选择性地积累在一个与包含 Nephroselmis 细胞体的液泡分开的液泡中。在叶绿体增大过程中，源自 Nephroselmis 的核中观察到明显的核仁，但没有异染色质，而自由生活的 Nephroselmis 细胞的核中则明确观察到压缩的异染色质。在源自 Nephroselmis 的叶绿体增大过程中，被摄取的 Nephroselmis 细胞的细胞膜解体。H. arenicola 的有丝分裂过程与其他 katablepharids 和 cryptophytes 非常相似。
