MACROMOLECULAR SYNTHESES RELATED TO THE REPRODUCTIVE CYST OF <i>TETRAHYMENA PATULA </i>

Gabe, Philip R.; Bault, Lawrence E. De

doi:10.1083/jcb.59.3.615

Cited by 13 publications

(5 citation statements)

References 13 publications

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“…This is shown not only by conformity to Model I1 but also by mutational analysis (11). Such behavior has also been found in the formation of cysts of Tetrahymena patula, in which there are successive macronuclear divisions without intervening DNA syntheses ( 12).…”

Section: Computer Simulationsupporting

confidence: 64%

Regulation of Macronuclear DNA Content in *Tetrahymena thermophila**†

Doerder

1979

The Journal of Protozoology

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Synopsis. Unequal macronuclear division in Tetrahymena thermophila introduces variance into G1 macronuclei; unless eliminated such variance would result in continuous variation in DNA content. Analysis of G1 and G2 macronuclear variances reveals that the added variance is eliminated by action on the extremes of macronuclear DNA content. In this model (Model II), macronuclei with small amounts of DNA have an additional complete S phase, while those with large amounts of DNA skip S. From available data, chromatin extrusion is shown not to contribute significantly, if at all, to the elimination of variance. Computer simulations utilizing haploid subunits indicate that model II predictions apply reasonably well to experimental data in terms of coefficients of variation, mean DNA content, and frequency of additional and skipped S phases. The simulations reveal also that within certain constraints, particularly the thresholds for additional and skipped S phases, macronuclear assortment is unaffected by Model II regulation. The relationships between Model II and other aspects of the cell cycle are briefly discussed.

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Section: Computer Simulationsupporting

confidence: 64%

Regulation of Macronuclear DNA Content in *Tetrahymena thermophila**†

Doerder

1979

The Journal of Protozoology

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“…These spherical cells capable of dividing are considered cysts because of their tolerance to desiccation 5 . Their ability to divide is compatible with their cyst status as demonstrated for the “reproductive cysts” of some free-living ciliates 6,7 . Cyst division is also observed in Rhodospirillum centenum , an anoxygenic photosynthetic and thermotolerant bacterium, when depleted of nutrients 8 .…”

Section: Introductionmentioning

confidence: 54%

Light on the cell cycle of the non-photosynthetic bacterium Ramlibacter tataouinensis

Luca

Fochesato

Lavergne

et al. 2019

Sci Rep

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Ramlibacter tataouinensis TTB310, a non-photosynthetic betaproteobacterium isolated from a semi-arid region of southern Tunisia, forms both rods and cysts. Cysts are resistant to desiccation and divide when water and nutrients are available. Rods are motile and capable of dissemination. Due to the strong correlation between sunlight and desiccation, light is probably an important external signal for anticipating desiccating conditions. Six genes encoding potential light sensors were identified in strain TTB310. Two genes encode for bacteriophytochromes, while the four remaining genes encode for putative blue light receptors. We determined the spectral and photochemical properties of the two recombinant bacteriophytochromes RtBphP1 and RtBphP2. In both cases, they act as sensitive red light detectors. Cyst divisions and a complete cyst-rod-cyst cycle are the main processes in darkness, whereas rod divisions predominate in red or far-red light. Mutant phenotypes caused by the inactivation of genes encoding bacteriophytochromes or heme oxygenase clearly show that both bacteriophytochromes are involved in regulating the rod-rod division. This process could favor rapid rod divisions at sunrise, after dew formation but before the progressive onset of desiccation. Our study provides the first evidence of a light-based strategy evolved in a non-photosynthetic bacterium to exploit scarse water in a desert environment.

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“…In all conditions thus far investigated in which T. pyriformis cells are growing in nutrient medium-regardless of their developmental status-macronuclear DNA accumulation takes place, whereas in all nongrowing situations it does not (e.g., reference 24). This relationship also holds in a dramatic way in polymorphic Tetrahymena species (14,30). The relationship between cell growth and macronuclear DNA synthesis may, however, be highly indirect.…”

Section: Relationships Of Clusters Of Cell-cycle Processes: a Minimalmentioning

confidence: 98%

“…As shown in this study and earlier in other strains of T. pyriformis by Jeffery et al (38,39) and Cleffmann (7-9), completion of a round of macronuclear DNA synthesis is not sufficient for cell division; two successive rounds of macronuclear DNA synthesis within one cell division cycle may occur even in undisturbed wildtype cells (8). Conversely, cell division cycles (including oral development) have been observed in the absence of ongoing macronuclear DNA synthesis after heat-shock synchronization in T. pyriformis (39,43) and normally in T. patula (30) and T. paravorax (14). A temporal setback of cell division brought about by manipulation of temperature affects the events of clusters A and B more severely than macronuclear DNA synthesis, as shown both in this study and in earlier work with the amicronucleate strain GL-C (compare reference 39 to reference 19).…”

Section: Relationships Of Clusters Of Cell-cycle Processes: a Minimalmentioning

confidence: 99%

Causal relations among cell cycle processes in Tetrahymena pyriformis. An analysis employing temperature-sensitive mutants.

Frankel¹,

Jenkins²,

DeBault³

1976

The Journal of Cell Biology

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Utilization of temperature-sensitive mutants of Tetrahymena pyriformis affected in cell division or developmental pathway selection has permitted elucidation of causal dependencies interrelating micronuclear and macronuclear replication and division, oral development, and cytokinesis. In those mutants in which cell division is specifically blocked at restrictive temperatures, micronuclear division proceeds with somewhat accelerated periodicity but maintains normal coupling to predivision oral development. Macronuclear division is almost totally suppressed in an early acting mutant (mol a) that prevents formation of the fission zone, and is variably affected in other mutants (such as mo3) that allow the fission zone to form but arrest constriction. However, macronuclear DNA synthesis can proceed for about four cycles in the nondividing mutant cells. A second class of mutants (psm) undergoes a switch of developmental pathway such that cells fail to enter division but instead repeatedly carry out an unusual type of oral replacement while growing in nutrient medium at the restrictive temperature. Under these circumstances no nuclei divide, yet macronuclear DNA accumulation continues. These results suggest that (a) macronuclear division is stringently affected by restriction of cell division, (b) micronuclear division and replication can continue in cells that are undergoing the type of oral development that is characteristic of division cycles, and (c) macronuclear DNA synthesis can continue in growing cells regardless of their developmental status. The observed relationships among events are consistent with the further suggestion that the cell cycle in this organism may consist of separate clusters of events, with a varying degree of coupling among clusters. A minimal model of the Tetrahymena cell cycle that takes these phenomena into account is suggested.One way to uncover causal relations between successive or simultaneous cellular developmental processes is to interfere selectively with one process and then observe the effects on the others. Microsurgical dissection provides a paradigm for this experimental logic: for example, Tartar (61) was able to demonstrate conclusively that the oral development of a ciliate is not necessary for the cell division that follows it, by simply cutting out the developing oral apparatus of Stentor and then observing that fission proceeds nonetheless. However, where cells are small and not readily operable, and/or the processes under study are pervasive physiological 242

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MACROMOLECULAR SYNTHESES RELATED TO THE REPRODUCTIVE CYST OF TETRAHYMENA PATULA

Cited by 13 publications

References 13 publications

Regulation of Macronuclear DNA Content in *Tetrahymena thermophila**†

Regulation of Macronuclear DNA Content in *Tetrahymena thermophila**†

Light on the cell cycle of the non-photosynthetic bacterium Ramlibacter tataouinensis

Causal relations among cell cycle processes in Tetrahymena pyriformis. An analysis employing temperature-sensitive mutants.

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MACROMOLECULAR SYNTHESES RELATED TO THE REPRODUCTIVE CYST OF TETRAHYMENA PATULA

Cited by 13 publications

References 13 publications

Regulation of Macronuclear DNA Content in Tetrahymena thermophila*†

Regulation of Macronuclear DNA Content in Tetrahymena thermophila*†

Light on the cell cycle of the non-photosynthetic bacterium Ramlibacter tataouinensis

Causal relations among cell cycle processes in Tetrahymena pyriformis. An analysis employing temperature-sensitive mutants.

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Product

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Regulation of Macronuclear DNA Content in *Tetrahymena thermophila**†

Regulation of Macronuclear DNA Content in *Tetrahymena thermophila**†