The endosymbiosis between Paramecium bursaria and Chlorella spp. is mutualistic. Symbiotic algae localize beneath the host Paramecium cell cortex compete for their attachment sites with preexisting organelle trichocysts. To examine the relationship between P. bursaria trichocysts and their symbiotic algae, algae-bearing or alga-free P. bursaria were starved for several days and the changes in the number of Chlorella sp. and presence or absence of trichocysts were evaluated. We conducted an indirect immunofluorescence microscopy with an anti-trichocyst monoclonal antibody against P. bursaria cells. Indirect immunofluorescence microscopy demonstrated that under starvation and darkness conditions, the immunofluorescence of trichocysts in alga-free P. bursaria decreased much faster than that in the normal algae-bearing P. bursaria . In the latter case, our observations proposed the possibility that the nutrition obtained from symbiotic algal digestion may promote trichocysts synthesis. This algal digestion mechanism may permit host P. bursaria cells to survive for a longer time under starvation condition. To the best of our knowledge, this may be a new benefit that host P. bursaria gain from harboring symbiotic algae.

中文翻译：

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饥饿草履虫中变异小球藻的自溶帮助宿主细胞抵抗饥饿压力

草履虫和小球藻之间的内共生。是互惠的。共生藻位于宿主草履虫细胞皮层下方，与预先存在的细胞器毛囊竞争它们的附着位点。为了检查 P. bursaria 毛囊菌与其共生藻类之间的关系，将含藻类或无藻类的 P. bursaria 饥饿数天，小球藻数量的变化。并评估是否存在毛囊虫。我们使用针对 P. bursaria 细胞的抗毛囊肿单克隆抗体进行了间接免疫荧光显微镜检查。间接免疫荧光显微镜观察表明，在饥饿和黑暗条件下，无藻 P. bursaria 毛囊虫的免疫荧光下降速度比正常含藻 P. bursaria 快得多。在后一种情况下，我们的观察提出了从共生藻类消化中获得的营养可能促进毛囊虫合成的可能性。这种藻类消化机制可能允许宿主 P. bursaria 细胞在饥饿条件下存活更长的时间。据我们所知，这可能是寄主 P. bursaria 从共生藻类中获得的新好处。