Sister chromatid exchange

About: Sister chromatid exchange is a research topic. Over the lifetime, 3187 publications have been published within this topic receiving 90029 citations. The topic is also known as: replication-born DSB repair by SCE & GO:1990414.

Structure of a palindromic amplicon junction implicates microhomology-mediated end joining as a mechanism of sister chromatid fusion during gene amplification.

Abstract: Amplification of the copy number of oncogenes is frequently associated with tumor progression. Often, the amplified DNA consists of large (tens to hundreds of kilobases) ‘head-to-head’ inverted repeat palindromes (amplicons). Several mechanisms have been proposed to explain palindrome formation but their relative contributions in nature have been difficult to assess without precise knowledge of the sequences involved at the junction of natural amplicons. Here, we have sequenced one such junction and compared this sequence to the un-rearranged structure, allowing us to pinpoint the site of sister chromatid fusion. Our results support a novel model, consistent with all described sister chromatid fusions, in which sister chromatid fusion is initiated by microhomology-mediated end joining of double strand breaks.

Sister chromatid exchanges in human lymphocytes treated in vitro with cadmium in Go and S phase of their cell cycles

Abstract: Sister chromatid exchanges (SCEs) were analyzed in human phytohemagglutinin-activated peripheral lymphocyte cultures exposed to varying concentrations (10 −7 –10 −3 M) of cadmium chloride in vitro at two different stages of the cell cycle, G o and early S phase. When cadmium chloride was administered at the G o phase, no increase in the SCEs were observed for the doses 10 −6 and 10 −5 M. Concentrations equal to or larger than 10 −4 M cadmium chloride were lethal to human lymphocytes in our experimental conditions. A highly statistically significant increase was observed in the SCE frequency with increasing cadmium chloride concentration (10 −7 –10 −4 ) when cadmium was administered at the early S phase, which was 24 h after culture initiation. The increase in SCE frequency was higher when the cultures were terminated at 54 h, compared to termination at 72 h. In order to examine the effects of cadmium administered at the S phase on SCE frequency in different individuals, 10 −5 M concentration was used and the cultures were terminated at 54 h after culture initiation. A 2- to 3-fold increase in the SCE frequency was observed in all six individuals examined. A progressive decrease in the proliferative index was also observed by increasing cadmium chloride concentration. These results demonstrate that the genotoxicity of cadmium chloride may be changed depending on the stage of the cell cycle in human lymphocytes. This may be one of the reasons of contradictory findings in the literature.

Persistently elevated sister chromatid exchanges in ethylene oxide-exposed primates: the role of a subpopulation of high frequency cells.

Abstract: Ethylene oxide (EtO) is a potent DNA-alkylating agent which has been shown to induce sister chromatid exchanges (SCE) in the peripheral blood lymphocytes of exposed workers. To study further the persistence of EtO-induced SCE, we have examined lymphocytes from a group of cynomolgus monkeys exposed to EtO in control, 50-ppm, and 100-ppm concentrations for 7 h/day, 5 days/week over the years 1979–1981. The data collected in 1987 were compared with those generated immediately prior to the cessation of exposure in 1981. EtO-induced SCE persisted at levels significantly above those of the nonexposed controls. Comparison of the distributions of SCE between 1979 and 1987 shows that, although mean SCE decreased from 1981 to 1987, the mean SCE in the top 10% of the distribution has not diminished over time. Consequently, the increased level of SCE is entirely attributable to a subpopulation of cells with high frequencies of SCE. These findings suggest that long-lived lymphocytes may inefficiently repair EtO-induced lesions which produce SCE. The results also have important implications for the proper use of SCE analytical techniques in the epidemiological study of cytogenetic damage after chronic exposure to DNA-alkylating agents.

Sister chromatid exchange in chromosomes of cattle from three different breeds reared under similar conditions.

Abstract: IANNUZZI, L., DI MEO, G. P., PERUCATTI, A., FERRARA, L. and GUSTAVSSON, I. 1991. Sister chromatid exchange in chromosomes of cattle from three different breeds reared under similar conditions. - Heredifas 114: 201-205. Lund, Sweden. ISSN 0018-0661. Received December 4, 1990. Accepted March 25. 1991 A homogeneous group (same sex, age and environmental conditions) of 35 Italian cattle of the Podolian, Friesian, and Romagna breeds was investigated concerning the spontaneous incidence of sister chromatid exchange (SCE). The mean values of SCEskell were 7.9 f 3.4, 7.1 & 3.3, and 7.3 k 3.2 in the Podolian, the Friesian, and the Romagna breeds, respectively, with significant differences between the Podolian and the Friesian breeds. Simultaneous disclosure of SCEs and fluorescent G-bands in the lighter chromatid made possible the identification of chromosome 1, in addition to the biarmed X and Y chromosomes. The inter-chromosomal SCE-distribution revealed a nonrandom pattern due to significantly increased values of SCEs in chromosomes 1 and X, particularly in the Romagna breed.