Kinetics of Photoreactivation and Liquid‐holding Recovery in Yeast Cells

Johnson, R.G.; Haynes, Robert H.

doi:10.1111/j.1751-1097.1986.tb05623.x

Cited by 6 publications

(3 citation statements)

References 18 publications

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“…l (t) is the survival attained after a PER time of t min. We have shown (Johnson and Haynes, 1986) that…”

Section: Resultsmentioning

confidence: 92%

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Evidence From Photoreactivation Kinetics for Multiple Dna Photolyases in Yeast

Johnson¹,

Haynes²

1986

Photochem & Photobiology

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Abstract— We have analyzed the kinetics of photoreactivation of ultraviolet‐light‐irradiated cells of two strains of the yeast Saccharomyces cerevisiae. The analysis yields plots of h(t), the number of photorepairable lethal hits remaining in the cell as a function of the time t of exposure to a continuous source of photoreactivating light. In the case of one of the strains studied, an excision‐deficient haploid strain, it is found that the time‐dependence of h(t) is given by the sum of three decreasing exponential functions of t for stationary phase cultures grown at 23 or 30°C. When the culture is grown at 37°C. the fastest component is absent and the intermediate component is reduced in importance relative to the remaining slow component. In the case of the other strain, a diploid of wild‐type radiation resistance, h(t) is found to contain just one decreasing exponential for cultures grown at 23, 30, and 37°C. The rate constant depends on the growth temperature of the cells, decreasing with increasing temperature. The results are interpreted as evidence for multiple DNA photolyases in the sensitive haploid strain.

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“…l (t) is the survival attained after a PER time of t min. We have shown (Johnson and Haynes, 1986) that…”

Section: Resultsmentioning

confidence: 92%

“…The development of a method for analyzing the kinetics of survival-enhancement by continuous photoreactivation offers a way to check the findings of Fukui and Laskowski (Johnson and Haynes, 1986). This method uses measured survivals to calculate the number of unrepaired lethal lesions per cell.…”

Section: Introductionmentioning

confidence: 99%

Evidence From Photoreactivation Kinetics for Multiple Dna Photolyases in Yeast

Johnson¹,

Haynes²

1986

Photochem & Photobiology

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“…In collaboration with Eckardt and Kunz, the analysis was then applied to frequency and yield curves for UV-induced mutation and recombination in wildtype and NER-deficient diploid strains, and inducible components were detected. 36 Bob also analyzed the kinetics of photoreactivation and liquid holding 37 in collaboration with Ronald Johnson (who was on sabbatical leave from Trent University), and in so doing provided evidence for multiple DNA photolyases in yeast (although the data and mathematical analysis were not published until after two yeast photolyase-encoding genes were discovered). Finally, Bob and Darlene Ager, a Ph.D. student in his lab, carried out a series of complex studies 38 that culminated in the development of a novel mathematical technique for describing the lethal and recombinagenic interactions of a variety of physical and chemical agents, including UV, X-rays, heat, and EMS.…”

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confidence: 96%

In memoriam: Robert Hall Haynes

Kunz

Hanawalt

1999

Environ. Mol. Mutagen.

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Mutagenesis and mathematics: The allure of numbers

Haynes

1989

Environ and Mol Mutagen

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This paper sets out the "formal," "empirical," and "mechanistic" equations that my colleagues and I have developed for the description and analysis of dose-response data on the lethal and genetic effects of mutagens in microorganisms. These three types of equations are interrelated inasmuch as they are all based ultimately on the use of the Poisson distribution in the formal definition of lethal and mutational hit functions. Explicit mathematical expressions for these functions can be written down in either empirical or mechanistic terms. The empirical equations are obtained simply by writing the hit functions as finite polynomials with adjustable coefficients. The mechanistic equations are based on the assumptions of the "DNA damage-repair hypothesis." The mathematical formulation of this hypothesis entails an important change in the definition of the word "hit" from that used in the classical hit/target theory of radiation biology. The theoretical and practical applications of these various equations in mutation research are summarized briefly and their merits are assessed in light of recent advances in our understanding of the biochemical basis of mutagenesis.

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Kinetics of Photoreactivation and Liquid‐holding Recovery in Yeast Cells

Cited by 6 publications

References 18 publications

Evidence From Photoreactivation Kinetics for Multiple Dna Photolyases in Yeast

Evidence From Photoreactivation Kinetics for Multiple Dna Photolyases in Yeast

In memoriam: Robert Hall Haynes

Mutagenesis and mathematics: The allure of numbers

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