Hohman T C, McNeil P L, Muscatine L
J Cell Biol. 1982 Jul;94(1):56-63. doi: 10.1083/jcb.94.1.56.
Certain species of Chlorella live within the digestive cells of the fresh water cnidarian Hydra viridis. When introduced into the hydra gut, these symbiotic algae are phagocytized by digestive cells but avoid host digestion and persist at relatively constant numbers within host cells. In contrast, heat-killed symbionts are rapidly degraded after phagocytosis. Live symbionts appear to persist because host lysosomes fail to fuse with phagosomes containing live symbionts. Neither acid phosphatase nor ferritin was delivered via lysosomes into phagosomes containing live symbionts, whereas these lysosomal markers were found in 50% of the vacuoles containing heat-killed symbionts 1 h after phagocytosis. Treatment of symbiotic algae before phagocytosis with polycationic polypeptides abolishes algal persistence and perturbs the ability of these algae to control the release of photosynthate in vitro. Similarly, inhibition of photosynthesis and hence of the release of photosynthetic products as a result of prolonged darkness and 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) treatment also abolishes persistence. Symbiotic algae are not only protected from host digestive attack but are also selectively transported within host cells, moving from the apical site of phagocytosis to a basal position of permanent residence. This process too is disrupted by polycationic polypeptides, DCMU and darkness. Both algal persistence and transport may, therefore, be a function of the release of products from living, photosynthesizing symbionts. Vinblastine treatment of host animals blocked the movement of algae within host cells but did not perturb algal persistence: algal persistence and the transport of algae may be initiated by the same signal, but they are not interdependent processes.
某些小球藻物种生活在淡水刺胞动物绿水螅的消化细胞内。当被引入水螅肠道时，这些共生藻类会被消化细胞吞噬，但能避免被宿主消化，并在宿主细胞内以相对恒定的数量持续存在。相比之下，热灭活的共生体在吞噬后会迅速降解。活的共生体似乎能够持续存在是因为宿主溶酶体无法与含有活共生体的吞噬体融合。酸性磷酸酶和铁蛋白都不会通过溶酶体传递到含有活共生体的吞噬体中，而在吞噬1小时后，这些溶酶体标记物在50%含有热灭活共生体的液泡中被发现。在吞噬前用聚阳离子多肽处理共生藻类会消除藻类的持续存在，并扰乱这些藻类在体外控制光合产物释放的能力。同样，由于长时间黑暗和3-(3,4-二氯苯基)-1,1-二甲基脲（DCMU）处理导致光合作用受到抑制，从而光合产物释放受到抑制，也会消除持续存在。共生藻类不仅能免受宿主消化攻击，还能在宿主细胞内被选择性运输，从吞噬的顶端部位移动到永久居留的基部位置。这个过程同样会被聚阳离子多肽、DCMU和黑暗所破坏。因此，藻类的持续存在和运输可能都是来自活的、进行光合作用的共生体释放产物的作用。用长春花碱处理宿主动物会阻止藻类在宿主细胞内的移动，但不会扰乱藻类的持续存在：藻类的持续存在和藻类的运输可能由相同的信号启动，但它们不是相互依赖的过程。
