scholarly journals GENETIC ANALYSIS OF GAMMA-RAY MUTAGENESIS IN YEAST. II. ALLELE-SPECIFIC CONTROL OF MUTAGENESIS

Genetics ◽  
1979 ◽  
Vol 93 (2) ◽  
pp. 375-381 ◽  
Author(s):  
Richard H McKee ◽  
Christopher W Lawrence
Keyword(s):  
Genetic Analysis ◽  
Genetic Control ◽  
Gamma Ray ◽  
Uv Mutagenesis ◽  
Gene Functions ◽  
Allele Specific ◽  
Γ Rays ◽  
Specific Control

ABSTRACT We find that partially different sets of gene functions are required for the production of different kinds of mutations induced by 6OCo γ rays in Saccharomyces cereuisiae. This observation is very similar to others made previously with respect to UV mutagenesis (LAWRENCE and CHRISTENSEN 1978a,b, 1979) and confirms the conclusion that such distinctive patterns of genetic control reflect properties of the test alleles and their genetic locations, rather than the kinds of lesions required to revert them. The data also support the model of mutagenic repair outlined in the first paper of this series (MCKEE and LAWRENCE 1979), in which partially different sets of gene functions are required for the production of different kinds of mutations, the formation of mutations at different genetic sites and the induction of mutations by different mutagens.

scholarly journals GENETIC ANALYSIS OF GAMMA-RAY MUTAGENESIS IN YEAST. I. REVERSION IN RADIATION-SENSITIVE STRAINS

Genetics ◽  
1979 ◽  
Vol 93 (2) ◽  
pp. 361-373
Author(s):  
Richard H McKee ◽  
Christopher W Lawrence
Keyword(s):  
Ionizing Radiation ◽  
Genetic Analysis ◽  
Gamma Ray ◽  
Wild Type ◽  
Uv Mutagenesis ◽  
Major Pathway ◽  
Gene Functions ◽  
Γ Rays ◽  
Γ Ray ◽  
Type Strains

ABSTRACT The frequency of revertants induced by 6OCo γ rays of the ochre allele, cyc1-9, has been measured in radiation-sensitive strains carrying one of 19 nonallelic mutations and in wild-type strains. The results indicate that ionizing radiation mutagenesis depends on the activity of the RAD6 group of genes and that the gene functions employed are very similar, but probably not identical, to those that mediate UV mutagenesis. Repair activities dependent on the functions of the RAD50 through RAD57 loci, the major pathway for the repair of damage caused by ionizing radiation, do not appear to play any part in mutagenesis. A comparison between the γ-ray data and those obtained previously with UV (LAWRENCE and CHRISTENSEN 1976) and chemical mutagens (PRAKASH 1976) suggests that the RAD6 "mutagenic pathway" is in fact composed of a set of processes, some of which are concerned with error-prone, and some with error-free, recovery activities.

scholarly journals The SRS2 suppressor of rad6 mutations of Saccharomyces cerevisiae acts by channeling DNA lesions into the RAD52 DNA repair pathway.

Genetics ◽  
1990 ◽  
Vol 124 (4) ◽  
pp. 817-831 ◽  
Author(s):  
R H Schiestl ◽  
S Prakash ◽  
L Prakash
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Repair ◽  
Gamma Ray ◽  
Dna Lesions ◽  
Recombinational Repair ◽  
Repair Pathway ◽  
Uv Mutagenesis ◽  
Uv Sensitivity ◽  
Suppressor Mutations ◽  
Induced Mutagenesis

Abstract rad6 mutants of Saccharomyces cerevisiae are defective in the repair of damaged DNA, DNA damage induced mutagenesis, and sporulation. In order to identify genes that can substitute for RAD6 function, we have isolated genomic suppressors of the UV sensitivity of rad6 deletion (rad6 delta) mutations and show that they also suppress the gamma-ray sensitivity but not the UV mutagenesis or sporulation defects of rad6. The suppressors show semidominance for suppression of UV sensitivity and dominance for suppression of gamma-ray sensitivity. The six suppressor mutations we isolated are all alleles of the same locus and are also allelic to a previously described suppressor of the rad6-1 nonsense mutation, SRS2. We show that suppression of rad6 delta is dependent on the RAD52 recombinational repair pathway since suppression is not observed in the rad6 delta SRS2 strain containing an additional mutation in either the RAD51, RAD52, RAD54, RAD55 or RAD57 genes. Possible mechanisms by which SRS2 may channel unrepaired DNA lesions into the RAD52 DNA repair pathway are discussed.

scholarly journals Molecular Clouds Observed by the EGRET Gamma-Ray Telescope

1997 ◽  
Vol 170 ◽  
pp. 22-24 ◽  
Author(s):  
Seth. W. Digel ◽  
Stanley D. Hunter ◽  
Reshmi Mukherjee ◽  
Eugéne J. de Geus ◽  
Isabelle A. Grenier ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Molecular Clouds ◽  
Gamma Ray ◽  
Angular Resolution ◽  
Cosmic Ray ◽  
High Energy ◽  
Background Rejection ◽  
Γ Rays ◽  
Γ Ray ◽  
Production Mechanisms

EGRET, the high-energy γ-ray telescope on the Compton Gamma-Ray Observatory, has the sensitivity, angular resolution, and background rejection necessary to study diffuse γ-ray emission from the interstellar medium (ISM). High-energy γ rays produced in cosmic-ray (CR) interactions in the ISM can be used to determine the CR density and calibrate the CO line as a tracer of molecular mass. Dominant production mechanisms for γ rays of energies ∼30 MeV–30 GeV are the decay of pions produced in collisions of CR protons with ambient matter and Bremsstrahlung scattering of CR electrons.

scholarly journals Genetic Analysis of Field Trials of Sex-linked Translocation Strains for Genetic Control of the Australian Sheep Blowfly Lucilia cuprina (Wiedemann)

1985 ◽  
Vol 38 (3) ◽  
pp. 275 ◽  
Author(s):  
GG Foster ◽  
WG Vogt ◽  
TL Woodburn
Keyword(s):  
Genetic Analysis ◽  
Genetic Control ◽  
Poor Performance ◽  
Field Trials ◽  
Lucilia Cuprina ◽  
Native Population ◽  
Australian Sheep ◽  
Males And Females ◽  
Progeny Tests ◽  
Release Method

The results of progeny tests of males and females captured during two field trials of sex-linked translocation strains for genetic control of L. cuprina are presented. Males released as mature larvae survived to adulthood and mated with field females. However, the levels of genetic death introduced into the population were insufficient to suppress the native population. This was due partly to seasonal ineffectiveness of the release method, and partly to poor performance of the released males. On average, the mating competitiveness of the released males was only one-third that of field males, whereas their field-reared, translocation-bearing sons were fully competitive with native males.

scholarly journals Gamma-Ray Bursts and Binary Neutron Star Mergers

1996 ◽  
Vol 165 ◽  
pp. 489-502
Author(s):  
Tsvi Piran
Keyword(s):  
Neutron Star ◽  
Gravitational Radiation ◽  
Gamma Ray ◽  
Indirect Evidence ◽  
Gamma Ray Bursts ◽  
Binary Neutron Star ◽  
Merger Event ◽  
Γ Rays ◽  
Γ Ray ◽  
The One

Neutron star binaries, such as the one observed in the famous binary pulsar PSR 1913+16, end their life in a catastrophic merger event (denoted here NS2M). The merger releases ∼5 1053 ergs, mostly as neutrinos and gravitational radiation. A small fraction of this energy suffices to power γ-ray bursts (GRBs) at cosmological distances. Cosmological GRBs must pass, however, an optically thick fireball phase and the observed γ rays emerge only at the end of this phase. Hence, it is difficult to determine the nature of the source from present observations (the agreement between the rates of GRBs and NS2Ms providing only indirect evidence for this model). In the future a coinciding detection of a GRB and a gravitational-radiation signal could confirm this model.

scholarly journals A Possible Discovery of a Flaring 1012 eV Gamma-Ray Source near the Red Dwarf EV Lac

1995 ◽  
Vol 151 ◽  
pp. 78-79
Author(s):  
I.Yu. Alekseev ◽  
N.N. Chalenko ◽  
V.P. Fomin ◽  
R.E. Gershberg ◽  
O.R. Kalekin ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Electronic Device ◽  
Angular Size ◽  
High Energy ◽  
Optical Systems ◽  
Relativistic Electrons ◽  
Large Area ◽  
Γ Rays ◽  
Γ Ray ◽  
Ev Lac

During the 1994 coordinated observations of the red dwarf flare star EV Lac, the star was monitored in the very high energy (VHE) γ-ray range around 1012 eV with the Crimean ground-based γ-ray telescope GT-48. This telescope consists of two identical optical systems (Vladimirsky et al. 1994) which were directed in parallel on EV Lac.The detection principle of the VHE γ-rays is based on the Čerenkov radiation emitted by relativistic electrons and positrons. The latter are generated in the interaction of the γ-rays with nuclei in the Earth’s atmosphere that leads to an appearance of a shower of charged particles and γ-quanta. The duration of the Cherenkov radiation flash is very short, just about a few nanoseconds. The angular size of the shower is ∼ 1°. To detect such flashes we use an optical system with large area mirrors and a set of 37 photomultipliers (PMs) in the focal plane. Using the information from these PMs which are spaced hexagonally and correspond to a field of view of 2°.6 on the sky, we can obtain the image of an optical flash. The electronic device permits us to detect nanosecond flashes (40 ns exposure time and 12 μs readout dead-time).

scholarly journals A gamma ray-induced non-excitable membrane mutant in Paramecium caudatum: a behavioral and genetic analysis

1985 ◽  
Vol 46 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Mihoko Takahashi ◽  
Nobuyuki Haga ◽  
Todd Hennessey ◽  
Robert D. Hinrichsen ◽  
Ritsuo Hara
Keyword(s):  
Genetic Analysis ◽  
Gamma Ray ◽  
Excitable Membrane ◽  
Complementation Test ◽  
Paramecium Caudatum ◽  
Channel Function

SUMMARYA new CNR (caudatum non-reversal) mutant of Paramecium caudatum was isolated after gamma ray mutagenesis. This CNR lacks not only the transient inward Ca2+ current but also the sustained Ca2+ current. It was shown to complement the three known CNR mutants of P. caudatum (cnrA, cnrB and cnrC) by crossbreeding analyses. Thus, this new mutant belongs to a 4th CNR locus, designated cnrD. The defect of cnrD can be partially rescued by microinjection of cytoplasm from any of the three CNR mutants or the three Pawns (pwA, pwB and pwC) in P. tetraurelia. Since the three CNR genes have been shown to be different from the three Pawn genes by cytoplasmic complementation test (Haga et al. 1983), this result suggests that cnrD is the 7th non-excitable mutant in Paramecium. Thus, there are at least seven genes controlling Ca2+ channel function in Paramecium.

Negative Parity Levels in 30Si

1974 ◽  
Vol 52 (16) ◽  
pp. 1485-1491 ◽  
Author(s):  
M. Wayne Greene ◽  
H. H. Grawe ◽  
J. A. Kuehner
Keyword(s):  
Gamma Ray ◽  
Negative Parity ◽  
Coincidence Measurement ◽  
Model Structure ◽  
Polarization Direction ◽  
Decay Branch ◽  
Mean Lifetime ◽  
Doppler Shift Attenuation ◽  
Γ Rays ◽  
The Mean

A polarization direction correlation measurement of γ rays from the 7.044 MeV level in 30Si results in Jπ = 5− for this level and implies a Jπ = 4− assignment for the level at 6.503 MeV. A particle gamma ray coincidence measurement establishes a new decay branch (15 ± 4%) for the 6.503 MeV level to the 5.485 MeV Jπ = 3− level. The Doppler shift attenuation method was used to measure the mean lifetime of the 7.044 MeV level as [Formula: see text]. A simple shell model structure for the low lying negative parity states is presented and shown to be consistent with experimental measurements.

scholarly journals Radiocarbon Production by the Gamma-Ray Component of Supernova Explosions

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 599-604 ◽  
Author(s):  
Paul E. Damon ◽  
Dai Kaimei ◽  
Grant E. Kocharov ◽  
Irina B. Mikheeva ◽  
Alexei N. Peristykh
Keyword(s):  
Cross Section ◽  
Tree Rings ◽  
Confidence Level ◽  
Gamma Ray ◽  
Visual Observation ◽  
Total Production ◽  
Average Increase ◽  
Supernova Explosions ◽  
Γ Rays ◽  
Γ Ray

We selected SN1006, the brightest and closest to Earth of all supernovas historically observed, for a study of 14C production by e−,e+-bremsstrahlung cascades initiated by hard γ rays (>10 MeV) from that event. During the cascade, bremsstrahlung energies eventually fall within a giant (n,γ), (n,2γ) cross-section, peaking at 23 MeV and approaching effectively zero below 10 MeV and above 40 MeV. The neutrons are absorbed primarily in the reaction 14N(n,p)14C. Cellulose from single-year tree rings from ad 1003 to ad 1020 was measured to determine ∆14C. Three years after the first visual observation of SN1006, ∆14C rose and remained above pre-ad 1009 values until ad 1018. Comparison of the 7 years before ad 1009 with the 9 years following show an average increase of 6.1 ± 1.6 (s.d.)‰ (significant at the 99.6% confidence level). Such a pulse of 14C requires a total production of neutrons of 17.1 × 107n cm−2e, implying an input of 11.3 × 104 ergs cm−2e γ-ray energy. This requires the total supernova γ-ray energy (>10 MeV) to have been 1 × 1050 ergs.

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