Chromatids exchanges between

Figure 36-12. Sister chromatid exchanges between human chromosomes. These are detectabie by Giemsa staining of the chromosomes of ceiis repiicated for two cycies in the presence of bromodeoxyuridine. The arrows indicate some regions of exchange. (Courtesy of S Wolff and J Bodycote.)...

Genotoxic Effects. Evaluation of the genotoxicity of lead in humans has focused on evaluations of lymphocytes from occupationally or environmentally exposed persons (Table 2-10) and in vitro studies of structural chromosomal aberrations and sister chromatid exchange in cultures of lymphocytes taken from healthy individuals (Table 2-11). Results of studies with human lymphocyte cultures exposed in vitro to lead acetate were nearly equally divided between positive (Beek and Obe 1974 Niebuhr and Wulf 1984) and negative (Beek and Obe 1975 Deknudt and Deminatti 1978 Gasiorek and Bauchinger 1981 Schmid etal. 1972). 

Parodi, S., A.Zunino, L.Ottaggio, M.DeFerrari, and L.Santi. 1983. Lack of correlation between the capability of inducing sister-chromatid exchanges in vivo and... 

Human cells exposed to various nickel compounds have an increased frequency of chromosomal aberrations, although sister chromatid exchange frequency is unaffected. Cells from nickel refinery workers exposed to nickel monosulfide (0.2 mg Ni/m3) or nickel subsulfide (0.5 mg Ni/m3) showed a significant increase in the incidence of chromosomal aberrations (Boysen et al. 1980 WHO 1991 USPHS 1993). No correlation was evident between nickel exposure level and the frequency of aberrations (USPHS 1993). 

PCP concentrations in blood of 20 workers ranged between 0.023 and 0.775 mg/L and were below the biological tolerance value of 1.0 mg/L no effect on sister chromatid exchange or chromosomal aberrations (Ziemsen et al. 1987)... 

Pal, K. 1984. The relationship between the levels of DNA-hydrocarbon adducts and the formation of sister-chromatid exchanges in Chinese hamster ovary cells treated with derivatives of polycyclic aromatic hydrocarbons. Mutat. Res. 129 365-372. 

Chinese hamster, Cricetus sp. ovary cells, single acute dose ranging between 0.005 and 0.06 Gy Increased frequency of sister chromatid exchange at 0.005 Gy increased numbers of chromosomal aberrations at >0.02 Gy no significant increase in cell death 10... 

SCEs are reciprocal exchanges between sister chromatids. They result in a change in morphology of the chromosome but breakage and reunion are involved although the exact mechanism is unclear. They are thought to occur at homologous loci. 

Bradley, M.O., Hsu, I.C. and Harris, C.C. (1979). Relationships between sister chromatid exchange and mutagenicity, toxicity and DNA damage. Nature 282 318-320. 

Connell, J.R. (1979). The relationship between sister chromatid exchange, chromosome aberration and gene mutation induction by several reactive polycyclic hydrocarbon metabolites in cultured mammalian cells. Ini. J. Cancer 24 485 189. 

Sister chromatid exchange is a technique which reveals exchonges between chromatids by differential staining. 

NaF was not mutagenic in bacterial assays. Although fluoride has been shown to be clas-togenic in a variety of cell types, the mechanism of clastogenicity has been attributed to the effect of fluoride on the synthesis of proteins involved in DNA synthesis and/or repair, rather than direct interaction between fluoride and DNA. In general, there was no effect on sperm morphology or the frequency of chromosomal aberrations, micronuclei, sister chromatid exchange, or DNA strand breaks in rodents treated in vivo. ... 

Knadle, S. (1985) Synergistic interaction between hydroquinone and acetaldehyde in the induction of sister chromatid exchange in human lymphocytes in vitro. Cancer Res., 45, 4853-4857... 

Natarajan, A.T., Simons, J.W.I.M., Vogel, E.W. van Zeeland, A.A. (1984) Relationship between cell killing, chromosomal aberrations, sister-chromatid exchanges and point mutations induced by monofunctional alkylating agents in Chinese hamster cells. A correlation with different ethylation products in DNA. Mutat. Res., 128, 31-40... 

No significant difference was found between a control group and workers who had been exposed 10 years previously to 2,4,5-trichlorophenol, either as regards chromosomal damage or sister chromatid exchanges (Blank et al., 1983). 

After the DNA is replicated during prophase of the first meiotic division, the resulting sister chromatids remain associated at their centromeres. At this stage, each set of four homologous chromosomes exists as two pairs of chromatids. Genetic information is now exchanged between the closely associated homologous chromatids... 

SISTER CHROMATID EXCHANGE The exchange of segments between the two chromatids of a chromosome. 

Sister chromatid exchange Genetic process leading to the formation of reciprocal exchange of DNA between the two DNA molecules of a replicating chromosome. 

Yet, other studies involving electroplaters and welders report a higher incidence of chromosomal aberrations or sister chromatid exchanges in lymphocytes of workers than in controls. In one study, a causal relationship between chromium exposure and the observed effects could not be established... 

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