Genetic Analysis of Radiation-sensitive Mutations in the Slime Mould Dictyostelium discoideum

Welker, Dennis L.; Deering, R. A.

doi:10.1099/00221287-97-1-1

Cited by 27 publications

(8 citation statements)

References 25 publications

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“…discoideum (Welker & Deering, 1976, 1978, mutations resulting in increased sensitivity to radiation were assigned to eight different loci in five linkage groups: group I, radA; group 11, radH; group 111, radC, radG and radl; group IV, radD and radF; and group VI, radB. Strains carrying a mutation at any of these loci, except radC, were sensitive to both U.V.…”

Section: Discussionmentioning

confidence: 99%

“…survival curves for strains of D. discoideum carrying the radiation-sensitive alleles radA20 (strain HPSl) and radBI3 (strain HPS14) (Welker & Deering, 1976) are also shown in Fig. 1.…”

Section: R E S U L T Smentioning

confidence: 99%

“…sensitivity. Since strains carrying the radEl00 mutation are only moderately u.v.-sensitive, the spot test described by Welker & Deering (1976) could not be used to test the haploid segregants for U.V. sensitivity.…”

Section: Introductionmentioning

confidence: 99%

“…One class of genetic markers which have been used effectively in Escherichia coli (Van de Putte et al, 1965) and in yeast (Cox & Parry, 1968) and which have recently been described in Dictyostelium discoideum (Welker & Deering, 1976) are mutations causing increased sensitivity to radiation. These markers are valuable because they generally have little effect on the growth of an organism under standard laboratory conditions, but can be easily detected by exposing the organism to an artificial source of radiation.…”

Section: Introductionmentioning

confidence: 99%

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radE, a New Radiation-sensitive Locus in Dictyostelium discoideum

Coukell

Cameron

1979

Journal of General Microbiology

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247Dictyostelium discoideum strain M28, which has been used widely in genetic studies, was found to carry a radiation-sensitive mutation. This allele, termed rad-100, was recessive in heterozygous diploids and mapped in linkage group 111. Complementation analysis and survival studies on strains carrying rad-100 suggested that this allele defines a new radiationsensitive locus in D . discoideum, and this locus has been designated radE. radE strains were moderately sensitive to ultraviolet light (Dlo 90 J m-2) and slightly sensitive to 13'Cs gamma rays (Dlo 255 krad). radE strains also exhibited increased sensitivity to killing by N-methyl-N'-nitro-N-nitrosoguanidine but not by other alkylating agents such as ethyl methanesulphonate or methyl methanesulphonate. The frequency of spontaneous methanol-resistant (acrA) mutants was approximately the same in cultures of radE and radEf strains. However, when amoebae of these strains were irradiated with ultraviolet light, the frequency of induced mutants was significantly lower in cultures of the radE strain. Furthermore, when amoebae of wild-type strain NC4 were plated in the presence of caffeine after ultraviolet-irradiation, the survival curves were very similar to the curves obtained for amoebae of radE strains in the presence or in the absence of caffeine. These results suggest that the radElOO mutation and caffeine interfere with an error-prone DNA repair pathway in D . discoideum. & Parry, 1968) and which have recently been described in Dictyostelium discoideum (Welker & Deering, 1976) are mutations causing increased sensitivity to radiation. These markers are valuable because they generally have little effect on the growth of an organism under standard laboratory conditions, but can be easily detected by exposing the organism to an artificial source of radiation. Moreover, radiationsensitive strains carrying mutations at different loci can often be distinguished by their characteristic responses to different types of radiation and/or to certain chemicals. I N T R O D U C T I O N One class of genetic markers which have been used effectively in Escherichia coli (Van de Putte et al., 1965) and in yeast (CoxDuring a mutant hunt in this laboratory, Dr A. S. Tsang observed that one of our common laboratory stocks, strain HC9 1, was significantly more sensitive to ultraviolet (u.v.) irradiation than our other haploid stocks. To determine whether the u.v.-sensitive mutation in this strain could be a useful genetic marker and to establish the relationship of this allele to other radiation-sensitive alleles reported in D . discoideum, we have examined the sensitivity of strains carrying this mutation to radiation and to chemical mutagens, and the effect of this allele on the induction of mutations by u.v.-irradiation. We have also analysed the allele genetically and the results suggest that the mutation is at a new radiation-sensitive locus, radE.

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Section: Discussionmentioning

confidence: 99%

“…survival curves for strains of D. discoideum carrying the radiation-sensitive alleles radA20 (strain HPSl) and radBI3 (strain HPS14) (Welker & Deering, 1976) are also shown in Fig. 1.…”

Section: R E S U L T Smentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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radE, a New Radiation-sensitive Locus in Dictyostelium discoideum

Coukell

Cameron

1979

Journal of General Microbiology

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“…These drug-resistance mutations have been essential in genetic mapping in Dictyostelium (Alexander et al, 1986 ;Welker & Deering, 1976) and in integrating the genetic and physical maps of the Dictyostelium linkage groups (Loomis et al, 1995). However, the structural gene encoded by acrA has remained unknown for the past 25 years.…”

Section: Ma X U Garcia and C Roberts Contributed Equally To This mentioning

confidence: 99%

Methanol and acriflavine resistance in Dictyostelium are caused by loss of catalase The GenBank accession number for the sequence reported in this paper is AF090443.

et al. 2002

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Various chemicals with harmful effects are not themselves toxic, but are metabolized in vivo to produce toxic products. One example is methanol in Dictyostelium, which is lethal to cells containing the acrA gene, but relatively harmless to acrA mutants. This makes methanol resistance one of the tightest genetic selections in Dictyostelium. Loss of acrA also confers cross-resistance to unrelated compounds such as acriflavine and thiabendazole. We have used insertional mutagenesis to demonstrate that the acrA locus encodes the peroxisomal catalase A enzyme. Disruption of the catA gene results in parallel resistance to acriflavine. Molecular and biochemical studies of several previously characterized methanol-resistant strains reveal that each lacks catalase activity. One allele, acrA2, contains a 13 bp deletion which introduces a frameshift in the middle of the gene. The involvement of catalase in methanol resistance in Dictyostelium compares with its role in methanol metabolism in yeast and rodents. However, this is the first study to show that catalase is required for the toxicity of acriflavine. Our results imply that acriflavine and thiabendazole are precursors which must be oxidized to generate biologically active species. The catA/acrA gene is also a potentially invaluable negative selectable marker for Dictyostelium molecular genetics.

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In vivo nicking and rejoining of nuclear DNA in ultraviolet-irradiated radiation-resistant and sensitive strains of Dictyostelium discoideum

Welker

Deering

1979

Molec. Gen. Genet.

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Some aspects of DNA repair in several radiation-resistant and radiation-sensitive strains of Dictyostelium discoideum were investigated by using alkaline sucrose gradients to analyze for the production and resealing of single-strand breaks following irradiation with 254 nm UV. All radiation-resistant strains and all mutants assayed that are sensitive to both UV and 60Co gamma rays produced single-strand breaks in their nuclear DNA after a UV fluence of 15 M/m2. Mutants at the radC locus which are sensitive to UV but as resistant as their parental strains to 60Co gamma rays produced many fewer single-strand breaks in their DNA after irradiation with UV. Thus, the radC mutations alter a repair pathway specific for UV-induced DNA damage and presumably affect the activity of a UV-damage-specific endonuclease involved in excision repair. All radiation-resistant strains and all of our mutants sensitive to gamma rays rejoined much of their DNA during a three-hour post-UV-irradiation incubation, suggesting that these strains have at least a partially intact excision repair system.

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Genetic Analysis of Radiation-sensitive Mutations in the Slime Mould Dictyostelium discoideum

Cited by 27 publications

References 25 publications

radE, a New Radiation-sensitive Locus in Dictyostelium discoideum

radE, a New Radiation-sensitive Locus in Dictyostelium discoideum

Methanol and acriflavine resistance in Dictyostelium are caused by loss of catalase The GenBank accession number for the sequence reported in this paper is AF090443.

In vivo nicking and rejoining of nuclear DNA in ultraviolet-irradiated radiation-resistant and sensitive strains of Dictyostelium discoideum

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