Relationship between sister chromatid exchanges and DNA replication in somatic cells of Drosophila melanogaster

Chromosoma ◽  
1981 ◽  
Vol 83 (1) ◽  
pp. 81-91 ◽  
Author(s):  
Silvana Faccio Dolfini ◽  
Simonetta Cadirola
Keyword(s):  
Drosophila Melanogaster ◽  
Dna Replication ◽  
Sister Chromatid ◽  
Somatic Cells ◽  
Sister Chromatid Exchanges ◽  
Chromatid Exchanges

scholarly journals PRESENCE OF A BASE LINE LEVEL OF SISTER CHROMATID EXCHANGES IN SOMATIC CELLS OF DROSOPHILA MELANOGASTER IN VIVO AND IN VITRO

Genetics ◽  
1982 ◽  
Vol 100 (2) ◽  
pp. 259-278
Author(s):  
Hideo Tsuji
Keyword(s):  
Drosophila Melanogaster ◽  
Sister Chromatid ◽  
Ganglion Cells ◽  
Sister Chromatid Exchanges ◽  
Base Line ◽  
Cell Cycles ◽  
Chromatid Exchanges ◽  
Third Instar Larvae

ABSTRACT Sister chromatid exchanges (SCEs) under in vivo and in vitro conditions were examined in ganglion cells of third-instar larvae of Drosophila melanogaster (Oregon-R). In the in vivo experiment, third-instar larvae were fed on synthetic media containing 5-bromo-2′-deoxyuridine (BrdUrd). After two cell cycles, ganglia were dissected and treated with colchicine. In the in vitro experiment, the ganglia were also incubated in media containing BrdUrd for two cell cycles, and treated with colchicine. SCEs were scored in metaphase stained with Hoechst 33258 plus Giemsa. The frequencies of SCEs stayed constant in the range of 25-150 vg/ml and 0.25-2.5 vg/ml of BrdUrd in vivo and in vitro, respectively. SCEs gradually increased at higher concentrations, strongly suggesting that at least a fraction of the detected SCEs are spontaneous. The constant levels of SCE frequency were estimated, on the average, at 0.103 per cell per two cell cycles for females and 0.101 for males in vivo and at 0.096 for females and 0.091 for males in vitro. No difference was found in the SCE frequency between sexes at any of the BrdUrd concentrations. The analysis for the distribution of SCEs within chromosomes revealed an extraordinarily high proportion of the SCEs at the junctions between euchromatin and heterochromatin; the remaining SCEs were preferentially localized in the euchromatic regions of the chromosomes and in the heterochromatic Y chromosome. These results were largely inconsistent with those of Gatti et al. (1979).

Topoisomerase inhibitors can selectively interfere with different stages of simian virus 40 DNA replication

1986 ◽  
Vol 6 (12) ◽  
pp. 4221-4227
Author(s):  
R M Snapka
Keyword(s):  
Dna Replication ◽  
Sister Chromatid ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Sister Chromatid Exchanges ◽  
Replication Forks ◽  
Dna Breaks ◽  
Rapid Reversal ◽  
Chromatid Exchanges

I have found that antineoplastic drugs which are known to be inhibitors of mammalian DNA topoisomerases have pronounced and selective effects on simian virus 40 DNA replication. Ellipticine, 4'-(9-acridinylamino)methanesulfon-m-aniside, and Adriamycin blocked decatenation of newly replicated simian virus 40 daughter chromosomes in vivo. The arrested decatenation intermediates produced by these drugs contained single-strand DNA breaks. Ellipticine in particular produced these catenated dimers rapidly and efficiently. Removal of the drug resulted in rapid reversal of the block and completion of decatenation. The demonstration that these drugs interfere with decatenation suggests that they may exert their cytotoxic and antineoplastic effects by preventing the separation of newly replicated cellular chromosomes. Camptothecin rapidly breaks replication forks in growing Cairns structures. It is likely that the target of camptothecin is the "swivel" topoisomerase required for DNA replication and that it is located at or very near the replication fork in vivo. Evidence is presented that many of the broken Cairns structures are in fact half-completed sister chromatid exchanges. One pathway for the resolution of these structures is completion of the sister chromatid exchange to produce a circular head-to-tail dimer.

scholarly journals Topoisomerase inhibitors can selectively interfere with different stages of simian virus 40 DNA replication.

1986 ◽  
Vol 6 (12) ◽  
pp. 4221-4227 ◽  
Author(s):  
R M Snapka
Keyword(s):  
Dna Replication ◽  
Sister Chromatid ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Sister Chromatid Exchanges ◽  
Replication Forks ◽  
Dna Breaks ◽  
Rapid Reversal ◽  
Chromatid Exchanges

I have found that antineoplastic drugs which are known to be inhibitors of mammalian DNA topoisomerases have pronounced and selective effects on simian virus 40 DNA replication. Ellipticine, 4'-(9-acridinylamino)methanesulfon-m-aniside, and Adriamycin blocked decatenation of newly replicated simian virus 40 daughter chromosomes in vivo. The arrested decatenation intermediates produced by these drugs contained single-strand DNA breaks. Ellipticine in particular produced these catenated dimers rapidly and efficiently. Removal of the drug resulted in rapid reversal of the block and completion of decatenation. The demonstration that these drugs interfere with decatenation suggests that they may exert their cytotoxic and antineoplastic effects by preventing the separation of newly replicated cellular chromosomes. Camptothecin rapidly breaks replication forks in growing Cairns structures. It is likely that the target of camptothecin is the "swivel" topoisomerase required for DNA replication and that it is located at or very near the replication fork in vivo. Evidence is presented that many of the broken Cairns structures are in fact half-completed sister chromatid exchanges. One pathway for the resolution of these structures is completion of the sister chromatid exchange to produce a circular head-to-tail dimer.

LACK OF SPONTANEOUS SISTER CHROMATID EXCHANGES IN SOMATIC CELLS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1979 ◽  
Vol 91 (2) ◽  
pp. 255-274
Author(s):  
M Gatti ◽  
G Santini ◽  
S Pimpinelli ◽  
G Olivieri
Keyword(s):  
Drosophila Melanogaster ◽  
Sister Chromatid ◽  
Ring Chromosome ◽  
Sister Chromatid Exchanges ◽  
The Other ◽  
Hoechst 33258 ◽  
Wild Type ◽  
X Chromosomes ◽  
Sister Chromatids ◽  
Chromatid Exchanges

ABSTRACT Neural ganglia of wild type third-instar larvae of Drosophila melanogasier were incubated for 13 hours at various concentrations of BUdR (1, 3, 9, 27 μg/ml) . Metaphases were collected with colchicine, stained with Hoechst 33258, and scored under a fluorescence microscope. Metaphases in which the sister chromatids were clearly differentiated were scored for the presence of sister-chromatid exchanges (SCEs) . At the lowest concentration of BUdR (1 μg/ml), no SCEs were observed in either male or female neuroblasts. The SCEs were found at the higher concentrations of BUdR (3, 9 and 27 μg/ml) and with a greater frequency in females than in males. Therefore SCEs are not a spontaneous phenomenon in D. melanogasier, but are induced by BUdR incorporated in the DNA. A striking nonrandomness was found in the distribution of SCEs along the chromosomes. More than a third of the SCEs were clustered in the junctions between euchromatin and heterochromatin. The remaining SCEs were preferentially localized within the heterochromatic regions of the X chromosome and the autosomes and primarily on the entirely heterochromatic Y chromosome.—In order to find an alternative way of measuring the frequency of SCEs in Drosophila neuroblasts, the occurrence of double dicentric rings was studied in two stocks carrying monocentric ring-X chromosomes. One ring chromosome, C(I)TR94-2, shows a rate of dicentric ring formation corresponding to the frequency of SCEs observed in the BUdR-labelled rod chromosomes. The other ring studied, R(1)2, exhibits a frequency of SCEs higher than that observed with both C(I)TR94-2 and rod chromosomes.

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