Review. Voltaire - Historian. Brumfitt, J. H.

Taylor, F. A.

doi:10.1093/fs/12.4.370

Cited by 5 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This higher concentration of BrdU, 24,MM, is sufficient to produce a marked reduction in fluorescence. Employment of fluorescence quenching to monitor the incorporation of nonradioactive BrdU into chromosomes obviates the use of radioactivity, which has been implicated as a cause of sister chromatid exchanges (10)(11)(12)(13) (Fig. 4) (Fig.…”

mentioning

confidence: 99%

Sister Chromatid Exchanges, Indices of Human Chromosome Damage and Repair: Detection by Fluorescence and Induction by Mitomycin C

Latt

1974

Proc. Natl. Acad. Sci. U.S.A.

380

View full text Add to dashboard Cite

Sister chromatid exchanges in chromosomes from human lymphocytes grown two replication cycles in medium containing 5-bromodeoxyuridine can be detected by fluorescence microscopy after staining with the Jisbenzimidazole dye 33258 Hoechst. These exchanges are mucbh more frequent than chronosome or chromatid breaks and appear to be partly but not entirely due to 5-broxpodeoxyuridine incorporation. Sister

show abstract

mentioning

confidence: 99%

Sister Chromatid Exchanges, Indices of Human Chromosome Damage and Repair: Detection by Fluorescence and Induction by Mitomycin C

Latt

1974

Proc. Natl. Acad. Sci. U.S.A.

380

View full text Add to dashboard Cite

show abstract

“…The tritium in the cytoplasm of cells after incubation in H3-thymidine is neither in an acid-soluble fraction nor in RNA as was suggested by Brachet (1959), since it was not removed either by cold TCA or by hydrolysis for l0 minutes in 1 N HCI at 60°C (Taylor, 1958). Since the tritium was removed by DNase, it is probably in a deoxyribonucleotide polymer.…”

Section: Discussionmentioning

confidence: 81%

“…This will remove almost all of the RNA-uraeil while only 6 to 15 per cent of the DNAthymine is lost (Taylor, 1958;Taylor and McMaster, 1954). The slide was then rinsed in water, stained by the Feulgen reaction, and then rinsed in water and stored in 70 per cent alcohol until filmed.…”

Section: ~2mentioning

confidence: 99%

“…Stripping film (AR-10 Kodak) was applied to the slides according to the procedure outlined by Taylor and McMaster (1954). In all experiments, the film was exposed for 13 to 14 days and then developed according to the technique of Taylor (1960). After developing, the tissues which had not been subjected to the Feulgen reaction were stained with azure B bromide (0.025 per cent at pH 4.0 for 15 minutes).…”

Section: ~2mentioning

confidence: 99%

See 1 more Smart Citation

EVIDENCE FOR CYTOPLASMIC DNA IN ROOT CELLS OF NICOTIANA

Mourad

1965

The Journal of Cell Biology

View full text Add to dashboard Cite

Sterile root cultures from Nicotiana tabacum were grown with H3-thymidine added to the medium for various intervals. Incorporation of the labeled nucleoside into nuclear DNA occurred in a fraction of the nuclei which increased with time. In addition, the cytoplasm of all cclls incorporated cnough tritium to be rcadily dctected by autoradiography. The tritium was not rcmovcd by hydrolysis in 1 N HC1 at 60°C for l0 minutes, but was removed by digestion in a DNase solution which also removed nuclear DNA. The amount of tritium in the cytoplasm increased during the first 2 hours, but did not appear to increase significantl Y during the following 5 hours. If thc roots were transfcrrcd to unlabclcd medium aftcr 2 hours, the label was diluted faster than expected by growth without turnover of the labeled componcnt. If FUdR was added to the unlabeled medium, the depletion occurred faster during the first 6 hours, but later appeared to level off so that at l0 hours thesc cultures did not differ from those incubated without FUdR. However, the addition of an excess of unlabelcd carrier had no effect on the rate of depiction of the cytoplasmic label. Actinomycin D, which inhibited the incorporation of H3-cytidine into RNA in the root tips, had no effect on thc incorporation of Ha-thymidine into the cytoplasmic component. Howcver, Mitomycin C or a high concentration of deoxyadenosine inhibited the incorporation of H 3-thymidine into the cytoplasmic component as well as into the nuclear DNA. It is concluded that H3-thymidine is incorporated into a cytoplasmic fraction which has thc characteristics of DNA, with a mcasurable rate of turnover. This fraction is synthesized regardless of whether or not the nucleus is synthesizing DNA. Although the function of cytoplasmic fraction is not yet known, it does not appear to be that of supplying precursors for thc synthesis of the nuclear DNA.

show abstract

“…This was based on the types of ring chromosomes induced by x-irradiating Chinese hamster ovary (CHO) cells in the Gi stage of the cell cycle. When broken chromosomes rejoin, the way in which the polynucleotide strands of DNA can rejoin is restricted according to the polarity (3'-5') of the strands (2,3). Thus, if the two broken ends of a chromosome containing only conventional linkages rejoin, the ring that is formed can separate into two rings at the subsequent anaphase.…”

mentioning

confidence: 99%

Cytological evidence for switches in polarity of chromosomal DNA.

Wolff¹,

Lindsley²,

Peacock³

1976

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

From the types of ring chromosomes induced in x-irradiated Chinese hamster ovary (CHO) cells, we deduce the existence of switches in the polarity of chromosomal DNA; if there is a continuous DNA double helix along the full length of the chromosome then the polarity switches imply 3'-3' and 5'-5' phosphodiester linkages. The resolution of the method is such that we estimate that there is one polarity switch for every 109 normal 3'-5' phosphodiester bonds.In a previous communication (1) we presented data that we interpreted as indicating the presence of infrequent switches in the polarity of chromosomal DNA, i.e., the equivalent of 3'-3' opposite 5'-5' linkages. This was based on the types of ring chromosomes induced by x-irradiating Chinese hamster ovary (CHO) cells in the Gi stage of the cell cycle. When broken chromosomes rejoin, the way in which the polynucleotide strands of DNA can rejoin is restricted according to the polarity (3'-5') of the strands (2, 3 sulting tetraploid metaphases (1). In addition to the paired rings and single rings formed by the orthodox rejoining of the two broken ends of a chromosome fragment with each other (Fig. 1A and C), single rings may also be formed by isolocus rejoining, i.e., reunion of complementary subunits of the DNA molecule (Fig. 1B). The essence of harlequin staining is that when two rounds of DNA replication are carried out in the presence of bromodeoxyuridine (BrdUrd), one chromatid is unifilarly substituted and stains darkly with fluorescence plus Giemsa whereas its sister chromatid is bifilarly substituted and stains lightly. In such material sister chromatid exchanges can be identified clearly as exchanges between light and dark chromatids. Thus, it is possible not only to determine whether ring chromosomes are paired or single, but also to ascertain whether sister chromatid exchange is responsible for the conformations observed.Because the centromere provides a reference point that is readily identifiable, we confine our attention to centric rings; furthermore, most rings scored were probibly derived from the three large metacentric chromosomes in the CHO complement. Consider a centric fragment in which the broken ends are in regions of like polarity and rejoin in the orthodox manner to form a ring (Fig. 1A). If no sister chromatid exchange occurs, a pair of monocentric rings will be found in the tetraploid descendent cell (Fig. la); one chromatid of each ring will be darkly stained (Fig. 2a). A sister chromatid exchange during the first post-irradiation round of DNA replication gives rise to a single dicentric ring with a twin exchange. This ring will be a symmetrical dicentric, i.e., will have centromeres that are diametrically opposite one another. The twin exchange can be recognized because there are two label switches so that one half of each chromatid is darkly stained, and the positions of the two exchanges are trans-symmetrical with respect to the centromeres (Figs. la and 2a). If the centric fragment has broken ends in regions of opposite polari...

show abstract

Review. Voltaire - Historian. Brumfitt, J. H.

Cited by 5 publications

References 0 publications

Sister Chromatid Exchanges, Indices of Human Chromosome Damage and Repair: Detection by Fluorescence and Induction by Mitomycin C

Sister Chromatid Exchanges, Indices of Human Chromosome Damage and Repair: Detection by Fluorescence and Induction by Mitomycin C

EVIDENCE FOR CYTOPLASMIC DNA IN ROOT CELLS OF NICOTIANA

Cytological evidence for switches in polarity of chromosomal DNA.

Contact Info

Product

Resources

About