Age-associated survival and extinction in mixed cultures of Paramecium

• Published in: European journal of protistology Vol. 37; no. 3; pp. 303 - 312
• Main Authors: Maruyama, Chiyuri, Fujisawa, Hiromi, Takagi, Yoshiomi
• Format: Journal Article
• Language: English
• Published: Stuttgart Elsevier GmbH 01.10.2001; Elsevier Science Ltd
• Subjects: Aging; Competition; Food vacuole formation; Paramecium; Paramecium multimicronucleatum; Paramecium tetraurelia; Survival and extinction; Competition; Aging; Survival and extinction; Food vacuole formation; Paramecium
• ISSN: 0932-4739; 1618-0429
• DOI: 10.1078/0932-4739-00835

When Paramecium tetraurelia (Pt) and P. multimicronucleatum (Pm) were cultured together, the outcome was either survival of Pt and extinction of Pm, or coexistence of Pt and Pm. We have shown that these fates were experimentally controllable by changing external culture conditions or by selecting stocks of Pm. However, we have so far failed to observe survival of Pm and extinction of Pt. We showed previously that the survival or extinction of Pm was associated with its ability or inability to form food vacuoles (FVs). An inability to form FVs is one of the characteristics of senescence in Paramecium. The extinction of Pm was observed only when stock CH312 of Pm was used, and this stock shows some senescent characteristics. Therefore, we studied the effects of clonal aging on the fate in mixed culture. Here, we report that all three possible fates including survival of Pm and extinction of Pt are controllable by changing the clonal age of Pt. Survival or extinction is also controllable between different age groups of the same species (Pt), indicating decisively that the phenomenon is not an inter-species problem. Cells without the ability to form FVs were found prior to the occurrence of extinction.