MITOCHONDRIAL INCORPORATION OF TRITIATED THYMIDINE IN <i>TETRAHYMENA PYRIFORMIS </i>

Parsons, J. A.

doi:10.1083/jcb.25.3.641

Cited by 70 publications

(16 citation statements)

References 15 publications

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“…TH~ mTOCHONORIA (Figure I a) are composed of a double membrane system of which the inner membrane, enclosing the matrix, forms the typical tubular structures. Mitochondria are autonomous organelles with independent DNA (110,137,131,136,II 1,14,41,13) and RNA species (133,134,18,46,135,13); they are capable of protein synthesis (2,146,13). Replication of mitochondrial DNA occurs throughout the cell cycle (111, 13), although synchronous replication is induced when 24-h starved cells are transferred to fresh growth medium (38).…”

Section: The Cell Organellesmentioning

confidence: 99%

On cell organelles in Tetrahymena. With special reference to mitochondria and peroxisomes

Nilsson

1981

Carlsberg Res. Commun.

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In the ciliate, Tetrahymena pyriformis, the population of cell organelles shows variation during the culture cycle and when the cells are subjected to various treatments. New cell constituents may appear and the fine structure of mitochondria and peroxisomes may change. Such dynamic structural changes are described and reviewed in relation to physiological and biochemical studies on Tetrahymena. The cell organelles discussed are about I tam in diameter or smaller~ reference is also made to the nuc[eotar organization which is the most sensitive indicator of the physiologica~ state of the ceils. The presumed distribution of the various cell organelles in subcellular fractions of Tetrahymena is mentioned, since dependent on the pretreatment of the cells, especially the mitochondrial and peroxisomal fractions may be contaminated to varying degrees with other cell organelles~The purpose of the review is to demonstrate that a correlation exists between the structure and function of cell organelles, especially mitochondria and peroxisomes, and that the overall fine structure of a cell reflects its physiological state.

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Section: The Cell Organellesmentioning

confidence: 99%

On cell organelles in Tetrahymena. With special reference to mitochondria and peroxisomes

Nilsson

1981

Carlsberg Res. Commun.

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“…The stability of the mitochondrial label is indicated by the data from one of four similar experiments. The average mitochondrial grain count of thymidine-3 H-labeled cells grown for four generations in unlabeled medium was presented in a previous paper (15). Since the average number of grains per mitochondrion did not differ significantly among individual cells within a single experiment, the data were grouped within each division class.…”

Section: Stability Of the Mitochondrial Labelmentioning

confidence: 99%

“…The slide was frozen on a block of dry ice, the cover slip was removed, and the slide air dried. Procedures for identification of the mitochondria and for the preparation of radioautographs have been described previously (15).…”

Section: Squash Proceduresmentioning

confidence: 99%

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THE DISTRIBUTION OF DNA AMONG DIVIDING MITOCHONDRIA OF TETRAHYMENA PYRIFORMIS

Parsons¹,

Rustad²

1968

The Journal of Cell Biology

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A squash technique was developed for log phase Tetrahymena pyriformis which permitted the resolution of over 100 individual mitochondria from a single cell. Mitochondria incorporated thymidine at all stages of the cell cycle, even when nuclear DNA synthesis was not occurring. During the stage of macronuclear DNA synthesis, however, there was a significant increase in the extent of mitochondrial labeling. Low radioautograph background suggests that mitochondrial DNA is synthesized at the mitochondria themselves. All mitochondria incorporated thymidine-3H within one population-doubling time. Grain counts also showed that the amount of mitochondrial label was retained for four generations and that this label remained randomly distributed among all mitochondria during this time. The results are not consistent with any theory of de-novo or "microbody" origin of mitochondria, but do support the hypothesis that mitochondria are produced by the growth and division of preexisting mitochondria. The stability of the mitochondrial DNA and its distribution among daughter mitochondria satisfy two prerequisites for a genetic material. The possibility is discussed that some of the genetic information for the mitochondrion is contained in the DNA associated with this organelle.

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“…In the eukaryotic microorganisms Tetrahymena pyriformis and Physarum polycephalum, mit-DNA synthesis occurred throughout the cell cycle (Parsons, 1965 ;Parsons and Rustad, 1968 ;Charret and Andre, 1968 ;Guttes et al ., 1967 ;Braun and Evans, 1969) . In contrast to these results, synthesis of mit-DNA in yeast was detected after replication of nuclear DNA and before bud formation (Smith et al, 1968 ;Cottrell and Avers, 1970) .…”

Section: Introductionmentioning

confidence: 99%

Synchronization of Mitochondrial Dna Synthesis in Chinese Hamster Cells (Line Cho) Deprived of Isoleucine

Ley

Murphy

1973

The Journal of Cell Biology

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Mitochondrial DNA (mit-DNA) synthesis was compared in suspension cultures of Chinese hamster cells (line CHO) whose cell cycle events had been synchronized by isoleucine deprivation or mitotic selection . At hourly intervals during cell cycle progression, synchronized cells were exposed to tritiated thymidine ([3H]TdR), homogenized, and nuclei and mitochondria isolated by differential centrifugation . Mit-DNA and nuclear DNA were isolated and incorporation of radioisotope measured as counts per minute ([3H]TdR) per microgram DNA . Mit-DNA synthesis in cells synchronized by mitotic selection began after 4 h and continued for approximately 9 h . This time-course pattern resembled that of nuclear DNA synthesis . In contrast, mit-DNA synthesis in cells synchronized by isoleucine deprivation did not begin until 9-12 h after addition of isoleucine and virtually all [3H]TdR was incorporated during a 3-h interval . We have concluded from these results that mit-DNA synthesis is inhibited in CHO cells which are arrested in G i because of isoleucine deprivation and that addition of isoleucine stimulates synchronous synthesis of mit-DNA . We believe this method of synchronizing mit-DNA synthesis may be of value in studies of factors which regulate synthesis of mit-DNA .

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MITOCHONDRIAL INCORPORATION OF TRITIATED THYMIDINE IN TETRAHYMENA PYRIFORMIS

Cited by 70 publications

References 15 publications

On cell organelles in Tetrahymena. With special reference to mitochondria and peroxisomes

On cell organelles in Tetrahymena. With special reference to mitochondria and peroxisomes

THE DISTRIBUTION OF DNA AMONG DIVIDING MITOCHONDRIA OF TETRAHYMENA PYRIFORMIS

Synchronization of Mitochondrial Dna Synthesis in Chinese Hamster Cells (Line Cho) Deprived of Isoleucine

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