Chapter 2 Cell Biology of Tetrahymena thermophila

Frankel, Joseph

doi:10.1016/s0091-679x(08)61528-9

Cited by 121 publications

(182 citation statements)

References 433 publications

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“…The ciliated protozoan Tetrahymena thermophila requires exogenous sources of the same 10 essential amino acids as animals, as well as serine and nucleotides (16). Starvation induces metabolic changes in T. thermophila that can be grouped into an early response lasting ϳ6 h followed by a longer term response.…”

Section: From the Department Of Molecular And Cell Biology Universitmentioning

confidence: 99%

Starvation-induced Cleavage of the tRNA Anticodon Loop in Tetrahymena thermophila

Lee

Collins

2005

Journal of Biological Chemistry

205

223

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Amino acid deprivation triggers dramatic physiological responses in all organisms, altering both the synthesis and destruction of RNA and protein. Here we describe, using the ciliate Tetrahymena thermophila, a previously unidentified response to amino acid deprivation in which mature transfer RNA (tRNA) is cleaved in the anticodon loop. We observed that anticodon loop cleavage affects a small fraction of most or all tRNA sequences. Accumulation of cleaved tRNA is temporally coordinated with the morphological and metabolic changes of adaptation to starvation. The starvation-induced endonucleolytic cleavage activity targets tRNAs that have undergone maturation by 5 and 3 end processing and base modification. Curiously, the majority of cleaved tRNAs lack the 3 terminal CCA nucleotides required for aminoacylation. Starvation-induced tRNA cleavage is inhibited in the presence of essential amino acids, independent of the persistence of other starvation-induced responses. Our findings suggest that anticodon loop cleavage may reduce the accumulation of uncharged tRNAs as part of a specific response induced by amino acid starvation.

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Section: From the Department Of Molecular And Cell Biology Universitmentioning

confidence: 99%

Starvation-induced Cleavage of the tRNA Anticodon Loop in Tetrahymena thermophila

Lee

Collins

2005

Journal of Biological Chemistry

205

223

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“…The Tetrahymena microtubule cytoskeleton includes a cortical cage that helps to determine cell size and shape and provides the framework for the rows of ciliary basal bodies and other cytoplasmic microtubules that mediate intracellular movements including micronuclear mitosis and meiosis (reviewed in Frankel, 1999). Each cell has two functionally distinct nuclei: the diploid germline micronucleus is transcriptionally silent and therefore not required for vegetative growth, and the somatic macronucleus contains ϳ45 copies of each gene and determines the phenotype of the cell.…”

Section: Introductionmentioning

confidence: 99%

Gene Knockouts Reveal Separate Functions for Two Cytoplasmic Dyneins inTetrahymena thermophila

Lee

Wisniewski

Dentler

et al. 1999

MBoC

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In many organisms, there are multiple isoforms of cytoplasmic dynein heavy chains, and division of labor among the isoforms would provide a mechanism to regulate dynein function. The targeted disruption of somatic genes in Tetrahymena thermophila presents the opportunity to determine the contributions of individual dynein isoforms in a single cell that expresses multiple dynein heavy chain genes. Substantial portions of two Tetrahymena cytoplasmic dynein heavy chain genes were cloned, and their motor domains were sequenced. Tetrahymena DYH1 encodes the ubiquitous cytoplasmic dynein Dyh1, and DYH2 encodes a second cytoplasmic dynein isoform, Dyh2. The disruption of DYH1, but not DYH2, resulted in cells with two detectable defects: 1) phagocytic activity was inhibited, and 2) the cells failed to distribute their chromosomes correctly during micronuclear mitosis. In contrast, the disruption of DYH2 resulted in a loss of regulation of cell size and cell shape and in the apparent inability of the cells to repair their cortical cytoskeletons. We conclude that the two dyneins perform separate tasks in Tetrahymena. INTRODUCTIONDynein is a molecular motor that transduces chemical energy into mechanical motion along microtubules. There are two functional classes of dynein: axonemal dynein that produces the propagated bending of cilia and of eukaryotic flagella and nonaxonemal or "cytoplasmic" dynein that performs functions other than ciliary beating. Cytoplasmic dynein is implicated in a variety of intracellular movements, including fast retrograde transport (Schroer et al., 1989;Muresan et al., 1996), slow axonal transport (Cleveland and Hoffman, 1991;Dillman et al., 1996), mediation of the trafficking of membrane-bounded organelles (Corthesy-Theulaz et al., 1992;Aniento et al., 1993;Fath et al., 1994;Oda et al., 1995;Holleran et al., 1996), the organization and separation of the bipolar mitotic spindle (Verde et al., 1991;Vaisberg et al., 1993;Saunders et al., 1995;Echeverri et al., 1996), and postmitotic nuclear migrations in yeast and filamentous fungi (Eshel et al., 1993;Li et al., 1993;Plamann et al., 1994;Xiang et al., 1994;Inoue et al., 1998).The realization that dynein performs so many different tasks and the discovery that many organisms express multiple dynein heavy chain genes lead to the hypothesis that different dynein isoforms perform different cellular tasks (reviewed in Asai, 1996). Cilia and eukaryotic flagella provide clear examples of dynein functional specialization (Piperno, 1990). The close coordination of ϳ12 distinct axonemal dynein heavy chains produces axonemal bending (e.g., Piperno and Ramanis, 1991;Mastronarde et al., 1992; reviewed in Brokaw, 1994).The functional specialization of the cytoplasmic dyneins is not well understood. All eukaryotes examined express homologues of the ubiquitous Dyh1 (also called MAP1C, cDHC1, DHC1a), and some organisms, including Saccharomyces, Aspergillus, Neurospora, and Dictyostelium, apparently have only this dynein. In the analysis of the family of dynein gen...

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“…Since almost all the cells became immobilized and spherical after exposure to 21 μM climacostol for 5 minutes, there might be no surviving cells in this condition. In Tetrahymena and related ciliates, many of the mitochondria are located in the cortex and are lined up parallel to the ciliary rows [13]. These mitochondrial organizations were visualized by loading it with mitochondria-specific dye MitoTracker Green [24].…”

Section: Morphological Alterations In Climacostol Treated Tetrahymenamentioning

confidence: 99%

“…They possess highly evolved cytoarchitecture as well as an intracellular messenger system regulating various cell functions [9,10]. Its ultrastructure, cell physiology, development, biochemistry, genetics and molecular biology have been extensively studied [11][12][13][14][15]. Moreover, the motile behavior of Tetrahymena in response to external chemical stimuli is easily assessed and has been used as a measure of the biological activity of various chemicals [16][17][18], making it a suitable model cell system for analysis of the cytotoxic mechanisms of climacostol.…”

Section: Introductionmentioning

confidence: 99%

Climacostol inhibits Tetrahymena motility and mitochondrial respiration

et al. 2010

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Climacostol is a resorcinol derivative that is produced by the ciliate Climacostomum virens. Exposure to purified climacostol results in lethal damage to the predatory ciliate Dileptus margaritifer and several other ciliates. To elucidate the mechanism of climacostol toxic action, we have investigated the effects of this compound on the swimming behavior of Tetrahymena thermophila and the respiratory system of isolated rat liver mitochondria. When added to living T. thermophila cells, climacostol markedly increased the turning frequency that was accompanied by a decrease in swimming velocity and subsequently by cell death. Observations by DIC and fluorescence microscopy showed morphological alterations in climacostol treated T. thermophila, indicating that climacostol might exert cytotoxic action on this organism. In the experiment with isolated rat liver mitochondria, climacostol was found to inhibit the NAD-linked respiration, but had no apparent effect on succinate-linked respiration. This finding indicates that climacostol specifically inhibits respiratory chain complex I in mitochondria. The combination of results suggest that the inhibition of mitochondrial respiration may be the cytotoxic mechanism of climacostol’s defenses against predatory protozoa.

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Chapter 2 Cell Biology of Tetrahymena thermophila

Cited by 121 publications

References 433 publications

Starvation-induced Cleavage of the tRNA Anticodon Loop in Tetrahymena thermophila

Starvation-induced Cleavage of the tRNA Anticodon Loop in Tetrahymena thermophila

Gene Knockouts Reveal Separate Functions for Two Cytoplasmic Dyneins inTetrahymena thermophila

Climacostol inhibits Tetrahymena motility and mitochondrial respiration

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