Symbiotic Chlorella sp of the ciliate Paramecium bursaria do not prevent acidification and lysosomal fusion of host digestive vacuoles during infection
Symbiotic Chlorella sp of the ciliate Paramecium bursaria do not prevent acidification and lysosomal fusion of host digestive vacuoles during infection
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DOI：
10.1007/s00709-005-0087-5
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发表时间：
2005-10-01
期刊：
影响因子：
2.9
通讯作者：
Fujishima, M
中科院分区：
文献类型：
--
作者：
Kodama, Y;Fujishima, M
每一个共生的纤毛草皮虫的小球藻都被包裹在一个由宿主消化液泡衍生的藻周液泡中，因此藻类被保护免受溶酶体融合的消化。无藻细胞可以被从带藻细胞中分离出来的藻类重新感染，通过摄入消化液泡。为了检测消化液泡酸化和溶酶体融合的时间以及藻类从消化液泡中逃逸的时间，将无藻类细胞与分离的藻类或酵母细胞混合，用pH指示染料在25 +/- 1℃下染色1.5分钟，清洗，追赶，并在不同的时间点固定。小球藻泡的酸化和消化分别在混合后0.5 min和2 min开始。混合0.5 h前存在于寄主细胞质中的绿色小球藻，0.5 h后全部被消化。混合1 h后，寄主细胞质中又出现了单个的绿藻，这是由那些同时含有未消化和部分消化藻类的消化液泡产生的，3 h时这类细胞的比例增加到40%左右。48 h时，单个绿藻开始通过细胞分裂繁殖。说明这些藻类成功地建立了内共生关系。与先前发表的研究相反，我们的数据表明，在酸酶体和溶酶体与宿主消化液泡融合后，藻类可以成功地从液泡中逃脱，从而产生内共生。
Each symbiotic Chlorella sp. of the ciliate Paramecium bursaria is enclosed in a perialgal vacuole derived from the host digestive vacuole, and thereby the alga is protected from digestion by lysosomal fusion. Algae-free cells can be reinfected with algae isolated from algae-bearing cells by ingestion into digestive vacuoles. To examine the timing of acidification and lysosomal fusion of the digestive vacuoles and of algal escape from the digestive vacuole, algae-free cells were mixed with isolated algae or yeast cells stained with pH indicator dyes at 25 +/- 1 degrees C for 1.5 min, washed, chased, and fixed at various time points. Acidification of the vacuoles and digestion of Chlorella sp. began at 0.5 and 2 min after mixing, respectively. All single green Chlorella sp. that had been present in the host cytoplasm before 0.5 h after mixing were digested by 0.5 h. At 1 h after mixing, however, single green algae reappeared in the host cytoplasm, arising from those digestive vacuoles containing both nondigested and partially digested algae, and the percentage of such cells increased to about 40% at 3 h. At 48 h, the single green algae began to multiply by cell division, indicating that these algae had succeeded in establishing endosymbiosis. In contrast to previously published studies, our data show that an alga can successfully escape from the host's digestive vacuole after acidosomal and lysosomal fusion with the vacuole has occurred, in order to produce endosymbiosis.