Quantitative analysis of trichocysts in Paramecium bursaria following artificial removal and infection with the symbiotic Chlorella variabilis

• Published in: European journal of protistology 2024-08, Vol.95, p.126115, Article 126115
• Main Authors: Morita, Hikaru, Kodama, Yuuki
• Format: Article
• Language: English
• Subjects: algae; Chlorella - physiology; Chlorella variabilis; Chlorella variabilis; Endosymbiosis; lysozyme; organelles; Paramecium - physiology; Paramecium bursaria; Protozoan Proteins - metabolism; Quantitative analysis; Symbiosis; Trichocyst isolation; Trichocysts
• ISSN: 0932-4739; 1618-0429; 1618-0429
• DOI: 10.1016/j.ejop.2024.126115

[Display omitted] •Trichocysts of Paramecium bursaria are situated close to the symbiotic Chlorella variabilis cells.•Paramecium specimens without algae regenerated higher numbers of trichocysts than those with algae.•Trichocyst protein levels changed before and after symbiosis with C. variabilis.•In this study, we developed a method for isolating pure trichocysts from P. bursaria.•Trichocysts may be less important for P. bursaria with algae than for P. bursaria without algae.•This study revealed a complex relationship between trichocysts and endosymbiotic algae. The ciliate Paramecium bursaria possesses cell organelles called trichocysts that have defensive functions. Paramecium bursaria is capable of symbiosis with Chlorella variabilis, and the symbiotic algae are situated in close proximity to the trichocysts. To clarify the relationship between trichocysts in P. bursaria and the presence or absence of the intracellular symbiotic C. variabilis, this study compared the regeneration capacity of trichocysts in alga-free and algae-bearing P. bursaria. In addition, trichocyst protein abundance was measured when alga-free P. bursaria specimens were artificially infected with Chlorella. After completely removing trichocysts from P. bursaria cells by treatment with lysozyme and observing them after 24 h, the percentage of regenerating trichocysts in the entire cell was significantly higher in alga-free cells than that in algae-bearing cells. We also developed a simple method for the isolation of high-purity trichocysts to quantify trichocyst protein amounts. There was a significant difference in the trichocyst protein abundance of P. bursaria before and one week after mixing with Chlorella (i.e., after the establishment of symbiosis with algae). This study shows the importance of trichocysts in alga-free P. bursaria as well as their competition with symbiotic C. variabilis for attachment sites during the algal infection process.