scholarly journals Evidence for an Inducible Repair-Recombination System in the Female Germ Line of Drosophila melanogaster. III. Correlation Between Reactivity Levels, Crossover Frequency and Repair Efficiency

Genetics ◽  
1997 ◽  
Vol 146 (4) ◽  
pp. 1333-1344 ◽  
Author(s):  
Anne Laurençon ◽  
Françoise Gay ◽  
Judith Ducau ◽  
Jean-Claude Bregliano
Keyword(s):  
Dna Repair ◽  
X Chromosome ◽  
Germ Line ◽  
Pericentromeric Region ◽  
Repair System ◽  
Recombination System ◽  
Repair Efficiency ◽  
Report Data ◽  
I Factor ◽  
Female Germ Line

We previously reported evidence that the so-called reactivity level, a peculiar cellular state of oocytes that regulates the frequency of transposition of I factor, a LINE element-like retrotransposon, might be one manifestation of a DNA repair system. In this article, we report data showing that the reactivity level is correlated with the frequency of crossing over, at least on the X chromosome and on the pericentromeric region of the third chromosome. Moreover, a check for X-chromosome losses and recessive lethals produced after gamma irradiation in flies with different reactivity levels, but common genetic backgrounds, brings more precise evidence for the relationship between reactivity levels and DNA repair. Those results support the existence of a repair-recombination system whose efficiency is modulated by endogenous and environmental factors. The implications of this biological system in connecting genomic variability and environment may shed new lights on adaptative mechanisms. We propose to call it VAMOS for variability modulation system.

scholarly journals Evidence for an inducible repair-recombination system in the female germ line of Drosophila melanogaster. II. Differential sensitivity to gamma rays.

Genetics ◽  
1995 ◽  
Vol 141 (2) ◽  
pp. 579-585 ◽  
Author(s):  
A Laurençon ◽  
J C Bregliano
Keyword(s):  
Drosophila Melanogaster ◽  
Gamma Rays ◽  
Germ Line ◽  
Differential Sensitivity ◽  
Repair System ◽  
Recombination System ◽  
I Factor ◽  
Female Germ Line ◽  
Dominant Lethals ◽  
Inducible Repair

Abstract In a previous paper, we reported that the reactivity level, which regulates the frequency of transposition of I factor, a LINE element-like retrotransposon, is enhanced by the same agents that induce the SOS response in Escherichia coli. In this report, we describe experimental evidence that, for identical genotypes, the reactivity levels correlate with the sensitivity of oogenesis to gamma rays, measured by the number of eggs laid and by frequency of dominant lethals. This strongly supports the hypothesis that the reactivity level is one manifestation of an inducible DNA repair system taking place in the female germ line of Drosophila melanogaster. The implications of this finding for the understanding of the regulation of I factor are discussed and some other possible biological roles of this system are outlined.

scholarly journals Evidence for an inducible repair-recombination system in the female germ line of Drosophila melanogaster. I. Induction by inhibitors of nucleotide synthesis and by gamma rays.

Genetics ◽  
1995 ◽  
Vol 141 (2) ◽  
pp. 571-578 ◽  
Author(s):  
J C Bregliano ◽  
A Laurençon ◽  
F Degroote
Keyword(s):  
Drosophila Melanogaster ◽  
Gamma Rays ◽  
Line Element ◽  
Germ Line ◽  
Nucleotide Synthesis ◽  
Transposition Frequency ◽  
Recombination System ◽  
I Factor ◽  
Female Germ Line ◽  
Inducible Repair

Abstract In the I-R system of hybrid dysgenesis in Drosophila melanogaster, the transposition frequency of I factor, a LINE element-like retrotransposon, is regulated by the reactivity level of the R mother. This reactivity is a cellular state maternally inherited but chromosomally determined, which has been shown to undergo heritable, cumulative and reversible changes with aging and some environmental conditions. We propose the hypothesis that this reactivity level is one manifestation of an inducible repair-recombination system whose biological role might be analogous to the SOS response in bacteria. In this paper, we show that inhibitors of DNA synthesis and gamma rays enhance the reactivity level in a very similar way. This enhancement is heritable, cumulative and reversible.

scholarly journals GENETIC ANALYSIS OF THREE DOMINANT FEMALE-STERILE MUTATIONS LOCATED ON THE X CHROMOSOME OF DROSOPHILA MELANOGASTER

Genetics ◽  
1983 ◽  
Vol 105 (2) ◽  
pp. 309-325
Author(s):  
D Busson ◽  
M Gans ◽  
K Komitopoulou ◽  
M Masson
Keyword(s):  
X Chromosome ◽  
Germ Line ◽  
Female Sterility ◽  
Recessive Mutation ◽  
Wild Type Allele ◽  
Wild Type ◽  
Allelic Series ◽  
Type Allele ◽  
Dominant Female ◽  
Female Germ Line

ABSTRACT Three dominant female-sterile mutations were isolated following ethyl methanesulfonate (EMS) mutagenesis. Females heterozygous for two of these mutations show atrophy of the ovaries and produce no eggs (ovoD  1) or few eggs (ovoD  2); females heterozygous for the third mutation, ovoD  3, lay flaccid eggs. All three mutations are germ line-dependent and map to the cytological region 4D-E on the X chromosome; they represent a single allelic series. Two doses of the wild-type allele restore fertility to females carrying ovoD  3 and ovoD  2, but females carrying ovoD  1 and three doses of the wild-type allele remain sterile. The three mutations are stable in males but are capable of reversion in females; reversion of the dominant mutations is accompanied by the appearance, in the same region, of a recessive mutation causing female sterility. We discuss the utility of these mutations as markers of clones induced in the female germ line by mitotic recombination as well as the nature of the mutations.

scholarly journals Maternal impairment of transposon regulation in Drosophila melanogaster by mutations in the genes aubergine, piwi and Suppressor of variegation 205

2010 ◽  
Vol 92 (4) ◽  
pp. 261-272 ◽  
Author(s):  
MICHAEL J. SIMMONS ◽  
MICHAEL W. THORP ◽  
JARED T. BUSCHETTE ◽  
KATHERINE PETERSON ◽  
ERIC W. CROSS ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Small Rnas ◽  
Germ Line ◽  
Associated Sequences ◽  
Female Germ Line ◽  
Maternal Impairment

SummaryTP5, a P element inserted in the telomere-associated sequences of the X chromosome, represses the excision of other P elements in the germ line through a combination of maternal and zygotic effects. The maternal component of this repression is impaired by heterozygous mutations in the aubergine and Suppressor of variegation 205 genes; one mutation in the piwi gene also appears to impair repression. In the female germ line, the level of TP5 mRNA is increased by these impairing mutations. The impairing aubergine and piwi mutations also increase the level of germ-line mRNA from CP, a transgene that encodes the P-element transposase; however, the Suppressor of variegation 205 mutation does not. These findings are discussed in terms of a model of P-element regulation that involves post-transcriptional and chromatin re-organizing events mediated by maternally transmitted small RNAs derived from the telomeric P element.

scholarly journals MUTAGENESIS IN OOCYTES OF DROSOPHILA MELANOGASTER. I. SCHEDULED SYNTHESIS OF NUCLEAR AND MITOCHONDRIAL DNA AND UNSCHEDULED DNA SYNTHESIS

Genetics ◽  
1983 ◽  
Vol 104 (2) ◽  
pp. 279-299
Author(s):  
Mark R Kelley ◽  
William R Lee
Keyword(s):  
Dna Repair ◽  
Mitochondrial Dna ◽  
Drosophila Melanogaster ◽  
Dna Synthesis ◽  
Nuclear Dna ◽  
Germ Line ◽  
Mutation Induction ◽  
Time Interval ◽  
Unscheduled Dna Synthesis ◽  
Female Germ Line

ABSTRACT As a model system for studying mutagenesis, the oocyte of Drosophila melanogaster has exhibited considerable complexity. Very few experiments have been conducted on the effect of exposing oocytes to chemical mutagens, presumably due to their lower mutational response relative to sperm and spermatids. This lower response may be due either to a change in probability of mutation induction per adduct due to a change in the type of DNA repair or to a lower dose of the mutagen to the female germ line. To study molecular dosimetry and DNA repair in the oocyte, the large number of intracellular constituents (mtDNA, RNA, nucleic acid precursors and large quantities of proteins and lipids) must be separated from nuclear DNA. In this paper we present results showing reliable separation of such molecules enabling us to detect scheduled nuclear and mitochondrial DNA synthesis. We also, by understanding the precise timing of such events, can detect unscheduled DNA synthesis (UDS) as a measure of DNA repair. Furthermore, by comparing the UDS results in a repair competent (Ore-R) vs. a repair deficient (mei-9L1) strain, we have shown the oocyte capable of DNA repair after treatment with ethyl methanesulfonate (EMS). We conclude that the important determinant of mutation induction in oocytes after treatment with EMS is the time interval between DNA alkylation and DNA synthesis after fertilization, i.e., the interruption of continuous DNA repair.

scholarly journals X Chromosome Crossover Formation and Genome Stability in Caenorhabditis elegans Are Independently Regulated by xnd-1

2016 ◽  
Vol 6 (12) ◽  
pp. 3913-3925 ◽  
Author(s):  
T Brooke McClendon ◽  
Rana Mainpal ◽  
Francis R G Amrit ◽  
Michael W Krause ◽  
Arjumand Ghazi ◽  
...  
Keyword(s):  
Dna Repair ◽  
Caenorhabditis Elegans ◽  
X Chromosome ◽  
Chromatin Structure ◽  
Transcriptional Activation ◽  
Genome Stability ◽  
Germ Line ◽  
Genome Instability ◽  
Ectopic Expression ◽  
Genome Integrity

Abstract The germ line efficiently combats numerous genotoxic insults to ensure the high fidelity propagation of unaltered genomic information across generations. Yet, germ cells in most metazoans also intentionally create double-strand breaks (DSBs) to promote DNA exchange between parental chromosomes, a process known as crossing over. Homologous recombination is employed in the repair of both genotoxic lesions and programmed DSBs, and many of the core DNA repair proteins function in both processes. In addition, DNA repair efficiency and crossover (CO) distribution are both influenced by local and global differences in chromatin structure, yet the interplay between chromatin structure, genome integrity, and meiotic fidelity is still poorly understood. We have used the xnd-1 mutant of Caenorhabditis elegans to explore the relationship between genome integrity and crossover formation. Known for its role in ensuring X chromosome CO formation and germ line development, we show that xnd-1 also regulates genome stability. xnd-1 mutants exhibited a mortal germ line, high embryonic lethality, high incidence of males, and sensitivity to ionizing radiation. We discovered that a hypomorphic allele of mys-1 suppressed these genome instability phenotypes of xnd-1, but did not suppress the CO defects, suggesting it serves as a separation-of-function allele. mys-1 encodes a histone acetyltransferase, whose homolog Tip60 acetylates H2AK5, a histone mark associated with transcriptional activation that is increased in xnd-1 mutant germ lines, raising the possibility that thresholds of H2AK5ac may differentially influence distinct germ line repair events. We also show that xnd-1 regulated him-5 transcriptionally, independently of mys-1, and that ectopic expression of him-5 suppressed the CO defects of xnd-1. Our work provides xnd-1 as a model in which to study the link between chromatin factors, gene expression, and genome stability.

EFFECT OF ARYL HYDROCARBON RECEPTOR AGONISTS AND LIPOPOLYSACCHARIDE ON BENZO(A)PYRENE GENOTOXICITY MARKERS

2019 ◽  
pp. 19-25 ◽  
Author(s):  
V. N. Babakov ◽  
N. Yu. Rogovskaya ◽  
I. D. Kurdyukov ◽  
P. P. Beltyukov ◽  
S. A. Dulov ◽  
...  
Keyword(s):  
Dna Repair ◽  
Aryl Hydrocarbon Receptor ◽  
P53 Protein ◽  
Control Level ◽  
Repair System ◽  
Human Hepatoma Cells ◽  
Kinase Activation ◽  
Receptor Agonists ◽  
Checkpoint Kinases ◽  
Aryl Hydrocarbon

The effect of aryl hydrocarbon receptor agonists (FICZ and ITE), as well as lipopolysaccharide under the toxic action of benzo(a)pyrene in HepaRG human hepatoma cells was evaluated. Active forms of the key stress-activated kinase cascades and DNA repair system proteins were used as markers of the genotoxic action of benzo(a)pyrene. A mixture of lipopolysaccharide with benzo(a)pyrene increases benzo(a)pyrene cytotoxicity and reduces the activation of DNA repair system proteins below the control level. Aryl hydrocarbon receptor agonists (FICZ and ITE) exhibit a cytoprotective effect against benzo(a) pyrene, enhance Akt1 kinase activation, and downregulate activation of the p53 protein and Chk1 and Chk2 checkpoint kinases. Thus, FICZ and ITE reduce the genotoxicity of benzo(a)pyrene.

pitkinD, a Novel Gain-of-Function Enhancer of Position-Effect Variegation, Affects Chromatin Regulation During Oogenesis and Early Embryogenesis in Drosophila

Genetics ◽  
2001 ◽  
Vol 157 (3) ◽  
pp. 1227-1244 ◽  
Author(s):  
Steffi Kuhfittig ◽  
János Szabad ◽  
Gunnar Schotta ◽  
Jan Hoffmann ◽  
Endre Máthé ◽  
...  
Keyword(s):  
Germ Line ◽  
Position Effect ◽  
Early Embryogenesis ◽  
Position Effect Variegation ◽  
Chromatin Regulation ◽  
Gain Of Function ◽  
Position Effects ◽  
Dominant Female ◽  
Effect Variegation ◽  
Female Germ Line

Abstract The vast majority of the >100 modifier genes of position-effect variegation (PEV) in Drosophila have been identified genetically as haplo-insufficient loci. Here, we describe pitkinDominant (ptnD), a gain-of-function enhancer mutation of PEV. Its exceptionally strong enhancer effect is evident as elevated spreading of heterochromatin-induced gene silencing along euchromatic regions in variegating rearrangements. The ptnD mutation causes ectopic binding of the SU(VAR)3-9 heterochromatin protein at many euchromatic sites and, unlike other modifiers of PEV, it also affects stable position effects. Specifically, it induces silencing of white+ transgenes inserted at a wide variety of euchromatic sites. ptnD is associated with dominant female sterility. +/+ embryos produced by ptnD/+ females mated with wild-type males die at the end of embryogenesis, whereas the ptnD/+ sibling embryos arrest development at cleavage cycle 1-3, due to a combined effect of maternally provided mutant product and an early zygotic lethal effect of ptnD. This is the earliest zygotic effect of a mutation so far reported in Drosophila. Germ-line mosaics show that ptn+ function is required for normal development in the female germ line. These results, together with effects on PEV and white+ transgenes, are consistent with the hypothesis that the ptn gene plays an important role in chromatin regulation during development of the female germ line and in early embryogenesis.

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