title: Calendar life-span versus fission life-span of Paramecium aurelia.
abstract: The hypothesis that paramecia use fissions, not days, to measure length of cell life-span was investigated. Parallel cell lines were grown at 27 C and at 24 C. The daily fission rate of the cells at 24 C was lower than at 27 C. If the cells count fissions, not days, the life-span in fissions should remain unchanged, whereas the cell life-span in days should increase in the lines with reduced daily fission rate. The results showed a significant increase in cell life-span in days when the cells were cultivated for 70-100% of their life cycle at 24 C. The life-span as measured by fissions, however, remained unchanged regardless of the time of the life cycle when cells were shifted to 24 C. The data indicate that, as a model system for cellular aging, paramecia are comparable to cells which use cell doublings to measure life-span.
mesh_terms: D000818:Animals; D002455:Cell Division; D002460:Cell Line; D002478:Cells, Cultured; D002910:Chronology as Topic; D002999:Clone Cells / Q000502:physiology; D010247:Paramecium / Q000502:physiology*; D012098:Reproduction; D012100:Reproduction, Asexual; D013696:Temperature; D013997:Time Factors