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.

scholarly journals Reduction of wild-type X chromosomes with the Ybb− chromosome of Drosophila melanogaster

1984 ◽  
Vol 43 (1) ◽  
pp. 93-98 ◽  
Author(s):  
Gioacchino Palumbo ◽  
Sharyn A. Endow ◽  
R. Scott Hawley
Keyword(s):  
Drosophila Melanogaster ◽  
Sister Chromatid ◽  
Sister Chromatid Exchanges ◽  
Ribosomal Genes ◽  
Nucleolus Organizer ◽  
Wild Type ◽  
X Chromosomes ◽  
Reduced Products ◽  
Detectable Difference ◽  
Chromatid Exchanges

SUMMARYThe Ybb− chromosome has been previously shown to induce reduction of X chromosome ribosomal genes in Xbb / Ybb− or Xbb+ / Ybb− flies. These reduction events are presumed to arise as one of the two products of unequal sister chromatid exchanges, which result in both magnified and reduced products. Bobbed reduced chromosomes may also arise as products of other recombinative events such as intrachromatid deletions. In this report we use the Ybb− chromosome to reduce the number of ribosomal genes present on X chromosomes from two wild-type stocks under ‘non-magnifying’ conditions. We then show that the bobbed reduced X chromosomes show no detectable difference in their Southern blot rDNA patterns when compared with the parental wild-type X chromosome. This indicates that reduction events do not preferentially delete certain repeat classes, and supports previous observations that the repeat types present in the D. melanogaster X chromosome nucleolus organizer are not significantly clustered.

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).

scholarly journals SOLO: a meiotic protein required for centromere cohesion, coorientation, and SMC1 localization in Drosophila melanogaster

2010 ◽  
Vol 188 (3) ◽  
pp. 335-349 ◽  
Author(s):  
Rihui Yan ◽  
Sharon E. Thomas ◽  
Jui-He Tsai ◽  
Yukihiro Yamada ◽  
Bruce D. McKee
Keyword(s):  
Drosophila Melanogaster ◽  
Sister Chromatid ◽  
Sister Chromatid Cohesion ◽  
Early Prophase ◽  
Wild Type ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Mutant Phenotypes ◽  
Meiosis I ◽  
Novel Protein

Sister chromatid cohesion is essential to maintain stable connections between homologues and sister chromatids during meiosis and to establish correct centromere orientation patterns on the meiosis I and II spindles. However, the meiotic cohesion apparatus in Drosophila melanogaster remains largely uncharacterized. We describe a novel protein, sisters on the loose (SOLO), which is essential for meiotic cohesion in Drosophila. In solo mutants, sister centromeres separate before prometaphase I, disrupting meiosis I centromere orientation and causing nondisjunction of both homologous and sister chromatids. Centromeric foci of the cohesin protein SMC1 are absent in solo mutants at all meiotic stages. SOLO and SMC1 colocalize to meiotic centromeres from early prophase I until anaphase II in wild-type males, but both proteins disappear prematurely at anaphase I in mutants for mei-S332, which encodes the Drosophila homologue of the cohesin protector protein shugoshin. The solo mutant phenotypes and the localization patterns of SOLO and SMC1 indicate that they function together to maintain sister chromatid cohesion in Drosophila meiosis.

Similar Sister Chromatid Arrangement in Mono- and Holocentric Plant Chromosomes

2016 ◽  
Vol 149 (3) ◽  
pp. 218-225 ◽  
Author(s):  
Veit Schubert ◽  
Mateusz Zelkowski ◽  
Sonja Klemme ◽  
Andreas Houben
Keyword(s):  
Sister Chromatid ◽  
Chromosome Complement ◽  
Super Resolution ◽  
Sister Chromatid Exchanges ◽  
Holocentric Chromosomes ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Plant Chromosomes ◽  
Sister Chromatids ◽  
Chromatid Exchanges

Due to the X-shape formation at somatic metaphase, the arrangement of the sister chromatids is obvious in monocentric chromosomes. In contrast, the sister chromatids of holocentric chromosomes cannot be distinguished even at mitotic metaphase. To clarify their organization, we differentially labelled the sister chromatids of holocentric Luzula and monocentric rye chromosomes by incorporating the base analogue EdU during replication. Using super-resolution structured illumination microscopy (SIM) and 3D rendering, we found that holocentric sister chromatids attach to each other at their contact surfaces similar to those of monocentrics in prometaphase. We found that sister chromatid exchanges (SCEs) are distributed homogeneously along the whole holocentric chromosomes of Luzula, and that their occurrence is increased compared to monocentric rye chromosomes. The SCE frequency of supernumerary B chromosomes, present additionally to the essential A chromosome complement of rye, does not differ from that of A chromosomes. Based on these results, models of the sister chromatid arrangement in mono- and holocentric plant chromosomes are presented.

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