scholarly journals DISTRIBUTION OF TRITIUM-LABELED DNA AMONG CHROMOSOMES DURING MEIOSIS

1965 ◽  
Vol 25 (2) ◽  
pp. 57-68 ◽  
Author(s):  
J. Herbert Taylor
Keyword(s):  
Quantitative Analysis ◽  
Sister Chromatid ◽  
Specific Activity ◽  
High Specific Activity ◽  
Sister Chromatid Exchanges ◽  
Size Group ◽  
Reciprocal Exchange ◽  
Chromatid Exchanges

Thymidine-H3 of high specific activity was used to study the distribution of labeled chromatids during meiotic divisions in spermatocytes of a species of grasshopper (Orthoptera). The distribution is regularly semiconservative as has been shown previously for mitosis, i.e., all chromatids are labeled after incorporation of thymidine-H3 into DNA at premeiotic interphase. If incorporation occurs at the interphase preceding this one, the chromosomes arrive at meiotic divisions with the equivalent of one chromatid of each homologue labeled. Chromatid exchanges occur at a frequency which is very nearly that predicted on the assumption that each chiasma represents an exchange between homologous chromatids. However, the exchanges are randomly distributed among chromosomes in a size group, whereas chiasmata are not. A quantitative analysis of the frequency and pattern of exchanges indicates that most of these result from breakage and reciprocal exchange between homologous chromatids. Sister chromatid exchanges are much less frequent and may be limited to premeiotic stages.

Diagnostic Ultrasound and Sister Chromatid Exchanges

1985 ◽  
Vol 40 (9) ◽  
pp. 589-590
Author(s):  
V. CIARAVINO ◽  
A. BRULFERT ◽  
M. W. MILLER ◽  
D. JACOBSON-KRAM ◽  
W. F. MORGAN
Keyword(s):  
Sister Chromatid ◽  
Diagnostic Ultrasound ◽  
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).

scholarly journals Sister chromatid exchanges and structural chromosome aberrations in relation to smoking in 91 individuals

Hereditas ◽  
2008 ◽  
Vol 98 (1) ◽  
pp. 77-81 ◽  
Author(s):  
K. HEDNER ◽  
B. HÖGSTEDT ◽  
A.-M. KOLNIG ◽  
E. MARK-VENDEL ◽  
B. STRÖMBECK ◽  
...  
Keyword(s):  
Sister Chromatid ◽  
Chromosome Aberrations ◽  
Sister Chromatid Exchanges ◽  
Structural Chromosome ◽  
Chromatid Exchanges

Distribution of sister chromatid exchanges on the mouse chromosomes in vivo with reference to the replication properties of the X chromosome

1984 ◽  
Vol 26 (2) ◽  
pp. 152-157
Author(s):  
S. M. Singh ◽  
D. L. Reimer
Keyword(s):  
Bone Marrow ◽  
X Chromosome ◽  
Sister Chromatid ◽  
Bone Marrow Cells ◽  
Relative Length ◽  
Chromosome Length ◽  
Sister Chromatid Exchanges ◽  
Chromatid Exchanges ◽  
Marrow Cells

Frequency of sister chromatid exchanges (SCE) were recorded separately for different chromosomes from bone marrow cells of female mice of the two genetic strains (C3H/S and C57BL/6J). SCEs were evaluated following different doses of 5-bromo-2′deoxyuridine (BrdU) as nine hourly i.p. injections. The SCE per cell increased with increasing BrdU doses which was slightly higher in C3H/S than in the C57BL/6J. SCEs per cell were variable at every treatment – strain combination, possibly reflecting the heterogeneous nature of the bone marrow cells. In general, there is a positive correlation between SCE per chromosome and the relative chromosome length. Total SCEs on one of the large chromosomes (most likely the X chromosome), however, are significantly higher than expected on the basis of relative length alone. Most of this increase is attributable to one of the homologues of this chromosome, which is not in synchrony with the rest of the chromosomes and may represent the late-replicating X. These results when viewed in the light of replication properties of the heterochromatinized X, suggest a direct involvement of DNA replication in SCE formation and may argue against the replication point as the sole site for the SCEs.Key words: sister chromatid exchange, BrdU, recombination, replication, X chromosome.

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