Genetics and Aging in Protozoa

Smith-Sonneborn, Joan

doi:10.1016/s0074-7696(08)61291-7

Cited by 48 publications

(12 citation statements)

References 141 publications

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“…It is therefore expected that autogamy immaturity would be shortened by measure of clock time under microgravity, which is known to raise the proliferation rate. Since the length of clonal life span of Paramecium may be related to the length of autogamy immaturity (Smith-Sonneborn, 1981;Ishikawa et al, 1998), proliferation at an increased rate under microgravity would result in a decrease in clonal life span.…”

Section: Discussionmentioning

confidence: 99%

Responses to Hypergravity in Proliferation of Paramecium tetraurelia

2003

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Section: Discussionmentioning

confidence: 99%

Responses to Hypergravity in Proliferation of Paramecium tetraurelia

2003

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“…caudatum, P. multimicronucleatum, P. jenningsi, E. patella, E. crassus, E. ninuta, E. woodruffi, Oxytricha bifaria, Stylonychia mytilus, Tokophrya lemnarum, T. rostrata, species of the T. pyriformis complex (general reviews by Sonneborn, 1957;Siegel, 1967;1. R. Preer, 1968;Bleyman, 1971;Grell, 1973;Nanney, 1974Nanney, , 1977Nanney, , 1980Nanney, , 1986Nanney and McCoy, 1976;Smith-Sonneborn, 1981;Takagi, 1988).…”

Section: The Life Cycle Of Ciliatesmentioning

confidence: 99%

Sex in Ciliates

Dini

Nyberg

1993

Advances in Microbial Ecology

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“…Although the lengths of clonal lifespan (Takagi et al, 1987a) and autogamy-immaturity (Komori et al, 2002) are very variable, the isolation of mutants that have shorter immaturity period in P. caudatum (Myohara & Hiwatashi, 1978), those that have shorter clonal lifespan in P. tetraurelia (Takagi et al, 1987b), and those that have longer period of autogamy-immaturity in P. tetraurelia (Komori et al, 2004(Komori et al, , 2005 indicates that the life cycle stages in Paramecium are genetically regulated. Although it has been reported in mammals (Cutler, 1978) and in ciliates (Smith-Sonneborn, 1981) that the lifespan is directly proportional to the age at sexual maturation, mutants with longer period of autogamy-immaturity were not related to the clonal lifespan (Komori et al, 2004(Komori et al, , 2005, suggesting that the interspecies rule between the lifespan and the immaturity period should not be applied to the intraspecies relation (Komori et al, 2005).…”

Section: Introductionmentioning

confidence: 90%

“…The length of each life cycle stage is counted by the number of fissions, rather than by the physical time (Takagi, 1988). Paramecium that has long been a model organism for cellular aging and clonal lifespan (Sonneborn, 1954(Sonneborn, , 1974Smith-Sonneborn, 1981, 1985Takagi, 1988Takagi, , 1999 proposes fascinating questions such as whether the maximal lifespan could be extended indefinitely or not, what would happen if the immaturity period was drastically shortened or elongated, whether the relationship might exist between the immaturity period and the lifespan, and so forth. These questions have been partly answered by mutant studies.…”

Section: Introductionmentioning

confidence: 99%

Novel features of computer-simulated clonal life of Paramecium caudatum

Uezu

Kakutani

Yoshida

et al. 2009

Journal of Theoretical Biology

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The clone of the ciliated protozoan Paramecium caudatum has the immaturity period of about 60 fissions and the lifespan of about 600 fissions. These life cycle figures have been depicted through laboratory experiments that allow continuous cell divisions for hundreds, which never occur in nature. We here constructed the nature-mimicking model culture that alternated the log-and stationary phases to allow conjugation, and computer-simulated the age structure modifying parameters such as cell distributions to start the culture, fission rates, death rates, immaturity periods, probabilities of conjugation, proportions of transplantation and so on. The average and maximum ages in the culture after thousands of alternations were converged to 43 ± 2 and 140 ± 5 fissions, respectively, when parameters for the immaturity period and the maximum clonal lifespan were set at 60 and 600 fissions.This result explains why cells collected in nature are usually young and vigorous.The average and maximum ages proportionally prolonged as the immaturity period was prolonged, as reported true for species of the ciliate. These results indicate the validity of our simulation. The average and maximum ages remained unchanged when the initial condition for starting the culture was changed from two complementary mating-type cells to a population with a quadratic-function * Corresponding author.: +81 742 20 3382: fax: +81 742 20 3382 E-mail address: uezu@cc.nara-wu.ac.jp 1 distribution, and when the fission rate at the log-phase and the death rate at the stationary phase were modified for older ages. The average and maximum ages changed slightly when either the conjugation rate or the proportion of transplantation was somewhat lowered. Although they changed considerably when such parameters as the immaturity period, conjugation rate and death rate were extremely modified, no clones with the age over 230 fissions appeared in any simulations. These results indicate the robustness of the model, which provides us with fresh insight into the structural system of the clonal lifespan of P. caudatum in nature.

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Genetics and Aging in Protozoa

Cited by 48 publications

References 141 publications

Responses to Hypergravity in Proliferation of Paramecium tetraurelia

Responses to Hypergravity in Proliferation of Paramecium tetraurelia

Sex in Ciliates

Novel features of computer-simulated clonal life of Paramecium caudatum

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