scholarly journals THE INDUCTION OF MITOTIC GENE CONVERSION BY X-IRRADIATION OF HAPLOID SACCHAROMYCES CEREVISIAE

Genetics ◽  
1973 ◽  
Vol 74 (2) ◽  
pp. 243-258
Author(s):  
D A Campbell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Conversion ◽  
Colony Formation ◽  
X Rays ◽  
Zygote Formation ◽  
X Ray ◽  
Sister Chromatids ◽  
X Irradiation ◽  
Radiation Induced ◽  
Mitotic Gene Conversion

ABSTRACT Mitotic recombination in Saccharomyces cerevisiae was examined by means of experiments in which one of the haploid parents was X-irradiated prior to zygote formation. By this method radiation-induced lesions are restricted to only one of the two non-sister chromatids that may be expected to undergo mitotic exchange in the diploid. The principal results of this work are: (1) X-irradiated haploid cells that are incapable of further vegetative growth (colony formation) are efficiently rescued into viable diploids by mating with unirradiated haploid cells. (2) X-rays delivered to only one of the two haploid parents are recombinogenic in the resultant diploid. The frequency of detected recombinational events increases as a probable linear function of the X-ray dose. (3) A majority of the induced recombinational events are nonreciprocal in nature (mitotic gene conversion). These results complement those obtained from X-irradiation of the vegetative diploid itself, where the induced genetic exchanges are principally reciprocal.

scholarly journals IN VIVO RADIOPROTECTIVE EFFECTS OF WHEATGRASS (TRITICUM AESTIVUM) EXTRACT AGAINST X-IRRADAITION-INDUCED OXIDATIVE STRESS AND APOPTOSIS IN PERIPHERAL BLOOD LYMPHOCYTES IN RATS

2018 ◽  
Vol 11 (4) ◽  
pp. 239
Author(s):  
Chandresh Shyam ◽  
Devinder K Dhawan ◽  
Vijayta D Chadha
Keyword(s):  
Oxidative Stress ◽  
Antioxidant Enzymes ◽  
Treated Group ◽  
Whole Body ◽  
Control Group ◽  
X Rays ◽  
X Ray ◽  
Peripheral Lymphocytes ◽  
X Irradiation ◽  
Radiation Induced

 Objectives: The present study was undertaken to investigate the possible protective potential of wheatgrass extract against radiation-induced toxicity in peripheral lymphocytes of rats exposed to a fractionated dose of X-rays.Methods: Effects of the X-irradiation with and without wheatgrass were studied on various parameters in peripheral lymphocytes including antioxidant defense system and apoptosis. Male Sprague-Dawley rats were divided into four different groups: Normal control group, X-ray-irradiated group (21 Gy over a span of 7 days), wheatgrass-treated group (80 mg/100 g bodyweight for 2 weeks), and X-rays-irradiated + wheatgrass-treated group. All the biochemical indices which included lipid peroxidation (LPO), reduced glutathione, reactive oxygen species (ROS), and activities of antioxidant enzymes were investigated in lymphocytes. Terminal deoxynucleotidyl transferase dUTP nick-end labeling assay was carried out to assess the apoptosis in lymphocytes following whole-body X-irradiation.Results: Whole-body X-irradiation to rats resulted in significant increase in LPO with concomitant depression of antioxidant enzymes activities, namely, superoxide dismutase, catalase, and glutathione peroxidise (GPx) in lymphocytes. Further, the present study witnessed a significant increase in the number of apoptotic lymphocytes in the X-irradiated animals. However, wheatgrass supplementation lowered the LPO levels, restored cellular antioxidant status, and provided significant protection against radiation-induced apoptosis.Conclusions: Based on these observations, the present study suggests that wheatgrass extract has the potential to be used as an effective radioprotectant against radiation-induced oxidative stress and apoptosis in peripheral lymphocytes of whole-body X-ray-exposed rats.

scholarly journals Induced rates of mitotic crossing over and possible mitotic gene conversion per wing anlage cell in Drosophila melanogaster by X rays and fission neutrons.

Genetics ◽  
1990 ◽  
Vol 126 (1) ◽  
pp. 157-166 ◽  
Author(s):  
T Ayaki ◽  
K Fujikawa ◽  
H Ryo ◽  
T Itoh ◽  
S Kondo
Keyword(s):  
Drosophila Melanogaster ◽  
Gene Conversion ◽  
Mitotic Recombination ◽  
X Rays ◽  
Strand Breaks ◽  
Order Of Magnitude ◽  
Radiation Induced ◽  
Secondary Result ◽  
Mitotic Gene Conversion ◽  
Fission Neutrons

Abstract As a model for chromosome aberrations, radiation-induced mitotic recombination of mwh and flr genes in Drosophila melanogaster strain (mwh +/+ flr) was quantitatively studied. Fission neutrons were five to six times more effective than X rays per unit dose in producing either crossover-mwh/flr twins and mwh singles-or flr singles, indicating that common processes are involved in the production of crossover and flr singles. The X-ray-induced rate/wing anlage cell/Gy for flr singles was 1 X 10(-5), whereas that of crossover was 2 x 10(-4); the former and the latter rate are of the same order of magnitude as those of gene conversion and crossover in yeast, respectively. Thus, we conclude that proximal-marker "flr" singles induced in the transheterozygote are gene convertants. Using the model based on yeast that recombination events result from repair of double-strand breaks or gaps, we propose that mitotic recombination in the fly is a secondary result of recombinational DNA repair. Evidence for recombinational misrepair in the fly is given. The relative ratio of radiation-induced mitotic crossover to spontaneous meiotic crossover is one order of magnitude higher in the fly than in yeast and humans.

Eds Of Radioactive Particles By Self-Induced Fluorescence

1990 ◽  
Vol 48 (2) ◽  
pp. 238-239
Author(s):  
Gregory L. Finch ◽  
Richard G. Cuddihy
Keyword(s):  
Electron Beam Irradiation ◽  
Nuclear Reactor ◽  
X Rays ◽  
Reactor Accident ◽  
Internal Radiation ◽  
X Ray ◽  
External Sources ◽  
X Irradiation ◽  
Available Information ◽  
Individual Particles

The elemental composition of individual particles is commonly measured by using energydispersive spectroscopic microanalysis (EDS) of samples excited with electron beam irradiation. Similarly, several investigators have characterized particles by using external monochromatic X-irradiation rather than electrons. However, there is little available information describing measurements of particulate characteristic X rays produced not from external sources of radiation, but rather from internal radiation contained within the particle itself. Here, we describe the low-energy (< 20 KeV) characteristic X-ray spectra produced by internal radiation self-excitation of two general types of particulate samples; individual radioactive particles produced during the Chernobyl nuclear reactor accident and radioactive fused aluminosilicate particles (FAP). In addition, we compare these spectra with those generated by conventional EDS.Approximately thirty radioactive particle samples from the Chernobyl accident were on a sample of wood that was near the reactor when the accident occurred. Individual particles still on the wood were microdissected from the bulk matrix after bulk autoradiography.

scholarly journals INCREASED SPONTANEOUS MITOTIC SEGREGATION IN MMS-SENSITIVE MUTANTS OF SACCHAROMYCES CEREVISIAE

Genetics ◽  
1977 ◽  
Vol 87 (2) ◽  
pp. 229-236
Author(s):  
Satya Prakash ◽  
Louise Prakash
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Methyl Methanesulfonate ◽  
X Rays ◽  
X Ray ◽  
Complementation Groups

ABSTRACT Methyl methanesulfonate (MMS)-sensitive mutants of Saccharomyces cerevisiae belonging to four different complementation groups, when homozygous, increase the rate of spontaneous mitotic segregation to canavanine resistance from heterozygous sensitive (canr/+) diploids by 13- to 170-fold. The mms8—1 mutant is MMS and X-ray sensitive and increases the rate of spontaneous mitotic segregation 170-fold. The mms9—1 and mms13—1 mutants are sensitive to X rays and UV, respectively, in addition to MMS, and increase the rate of spontaneous mitotic segregation by 13-fold and 85-fold, respectively. The mutant mms21—1 is sensitive to MMS, X rays and UV and increases the rate of spontaneous mitotic segregation 23-fold.

The Escherichia coli recA gene increases UV-induced mitotic gene conversion in Saccharomyces cerevisiae

1994 ◽  
Vol 25 (5) ◽  
pp. 472-474 ◽  
Author(s):  
Viera Vlčková ◽  
Luba Černáková ◽  
Eva Farkašová ◽  
Jela Brozmanová
Keyword(s):  
Escherichia Coli ◽  
Saccharomyces Cerevisiae ◽  
Gene Conversion ◽  
Reca Gene ◽  
Mitotic Gene Conversion

Developmental effects of X-irradiation of early Drosophila embryos

Development ◽  
1977 ◽  
Vol 39 (1) ◽  
pp. 253-259
Author(s):  
M. Bownes ◽  
L. A. Sunnell
Keyword(s):  
Early Embryogenesis ◽  
X Rays ◽  
X Ray ◽  
Developmental Effects ◽  
Morphological Defects ◽  
X Irradiation ◽  
Drosophila Embryos ◽  
Adult Cells

Drosophila embryos were treated at specific stages during early embryogenesis with various doses of X-irradiation. The lethality at various times during development was established and pattern defects in the adults noted. It was observed that the most sensitive stages of embryogenesis to X-ray-induced lethality were also the stages where most morphological defects were found in the adults which emerged. This suggests that presumptive larval and adult cells are sensitive to X-rays at the same stages of embryogenesis.

Evidence for Independent Mismatch Repair Processing on Opposite Sides of a Double-Strand Break in Saccharomyces cerevisiae

Genetics ◽  
1998 ◽  
Vol 148 (1) ◽  
pp. 59-70
Author(s):  
Yi-shin Weng ◽  
Jac A Nickoloff
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Conversion ◽  
Mismatch Repair ◽  
Strand Break ◽  
Double Strand Break ◽  
Stem Loop ◽  
Mitotic Gene Conversion ◽  
Low Levels ◽  
Mat Locus ◽  
Insertion Mutations

Abstract Double-strand break (DSB) induced gene conversion in Saccharomyces cerevisiae during meiosis and MAT switching is mediated primarily by mismatch repair of heteroduplex DNA (hDNA). We used nontandem ura3 duplications containing palindromic frameshift insertion mutations near an HO nuclease recognition site to test whether mismatch repair also mediates DSB-induced mitotic gene conversion at a non-MAT locus. Palindromic insertions included in hDNA are expected to produce a stem-loop mismatch, escape repair, and segregate to produce a sectored (Ura+/−) colony. If conversion occurs by gap repair, the insertion should be removed on both strands, and converted colonies will not be sectored. For both a 14-bp palindrome, and a 37-bp near-palindrome, ~75% of recombinant colonies were sectored, indicating that most DSB-induced mitotic gene conversion involves mismatch repair of hDNA. We also investigated mismatch repair of well-repaired markers flanking an unrepaired palindrome. As seen in previous studies, these additional markers increased loop repair (likely reflecting corepair). Among sectored products, few had additional segregating markers, indicating that the lack of repair at one marker is not associated with inefficient repair at nearby markers. Clear evidence was obtained for low levels of short tract mismatch repair. As seen with full gene conversions, donor alleles in sectored products were not altered. Markers on the same side of the DSB as the palindrome were involved in hDNA less often among sectored products than nonsectored products, but markers on the opposite side of the DSB showed similar hDNA involvement among both product classes. These results can be explained in terms of corepair, and they suggest that mismatch repair on opposite sides of a DSB involves distinct repair tracts.

scholarly journals Inaktivierungsversuche mit homozygoten Hefestämmen verschiedenen Ploidiegrades

1964 ◽  
Vol 19 (10) ◽  
pp. 929-935 ◽  
Author(s):  
Sigrid Hempel ◽  
Wolfgang Laskowski
Keyword(s):  
Succinic Acid ◽  
Effective Dose ◽  
Colony Formation ◽  
Daughter Cell ◽  
Distinct Difference ◽  
X Rays ◽  
Uv Treatment ◽  
Fermentation Processes ◽  
X Ray ◽  
Effective Doses

A diploid Saccaromyces strain was treated with several doses of X-rays, UV and succinic acid peroxyde (BPO). The inactivation of the ability to form macroscopic colonies as well as the ability to form microcolonies of at least two cells to a few hundred cells has been compared with the inactivation of respiration and fermentation intensity. If the inactivation of macroscopic colony formation is taken as a measure of the effective dose applied, the formation of at least one daughter cell as well as respiration and fermentation intensity is reduced to approximately the same extent after BPO and X-ray treatment. In the latter case, however, much higher effective doses have to be applied and a distinct difference between respiration and fermentation sensitivity is observed. After UV-treatment the formation of at least one daughter cell is exceedingly more sensitive than the fermentation processes. The respiration processes behave most UV resistant. Possible reasons for the observed different relative sensitivities are discussed.

X-ray radiation-induced amorphization of metal–organic frameworks

2019 ◽  
Vol 21 (23) ◽  
pp. 12389-12395 ◽  
Author(s):  
Remo N. Widmer ◽  
Giulio I. Lampronti ◽  
Nicola Casati ◽  
Stefan Farsang ◽  
Thomas D. Bennett ◽  
...  
Keyword(s):  
Radiation Damage ◽  
Metal Organic Frameworks ◽  
X Rays ◽  
X Ray ◽  
P Accumulation ◽  
Metal Organic ◽  
Radiation Induced ◽  
Crystalline Metal

Accumulation of radiation damage from synchrotron X-rays leads to complete amorphization of the initially crystalline metal–organic frameworks ZIF-4, ZIF-62, and ZIF-zni. The mechanism of this transformation is studied as a function of time and temperature and is shown to be non-isokinetic.

Sign in / Sign up

Export Citation Format

Share Document