Comparative Analyses of the Symbiotic Associations of the Host Paramecium bursaria with Free-Living and Native Symbiotic Species of Chlorella

Characterization of Crystals in Ciliate Paramecium bursaria Harboring Endosymbiotic Chlorella variabilis

“…1 b, left). The crystals were localized at the posterior end of the cell rather than beneath the cell cortex, and most crystals moved inside the cell via P. bursaria cytoplasmic streaming, as demonstrated in our previous study [ 30 ]. In contrast, a negligible number of crystals were found in algae-bearing cells (Fig.…”

“…The entry of algae into host P. bursaria cells may trigger the ejection of crystals occupying a major space in the cytoplasm to secure the space required for endosymbiotic association. Recently, [ 30 ] revealed a significantly decreased abundance of crystals, which almost disappeared when the original symbiotic Chlorella sp. was used to inoculate alga-free P. bursaria cells, whereas free-living Chlorella sp.…”

“…Interestingly, alga-free P. bursaria cells fed compatible Chlorella sp., such as the original symbiotic algae, lost their intracellular crystals during the algal infection process, but not when fed less compatible Chlorella sp., such as free-living Chlorella sp. [ 30 ]. Since one of the roles of crystals is as a storage reservoir for purines and organic nitrogen [ 3 ], the amount and composition of photosynthetic products of symbiotic algae may affect the host crystals.…”