Some factors affecting sister-chromatid differentiation (SCD) and sister-chromatid exchange (SCE) in Hordeum vulgare.

A study of some factors affecting sister-chromatid differentiation (SCD) and sister-chromatid exchanges (SCE) in Hordeum vulgare is reported. After we studied the influence of 5-fluorodeoxyuridine (FdU) and growth temperature on SCE in barley cells, and the effect of FdU, growth temperature, the growth time of plant cells in 5-bromo-2-deoxyuridine (BrdU) solution on SCD, we found an experimental condition under which the frequency of SCE is lower, but the percentage of SCD is higher. Our data show that ascorbic acid, mitomycin C, adriamycin, and maleic hydrazide induce SCEs in cells of Hordeum vulgare by means of free radicals. This can be shown from the two observations: (1) sulfhydryl compounds such as cysteine and glutathione can completely or partially inhibit the SCEs induced by ascorbic acid, mitomycin C, adriamycin and maleic hydrazide; (2) the amounts of free radicals in root tips correlate with the frequencies of SCE in root tip cells.     

Sister-chromatid exchanges and cell-cycle delay in Chinese hamster V79 cells treated with 9 organophosphorus compounds (8 pesticides and 1 defoliant)

Significant increase of sister-chromatid exchanges (SCE) in V79 cells treated with 2 organophosphorus pesticides (OPP), fenthion and oxydemeton-methyl, was observed. The other 7 compounds (6 OPP and 1 defoliant) namely, amaze, azinphos-methyl, bolstar, DEF-defoliant, fensulfothion, monitor and nemacur caused no increase of SCE frequencies at the doses tested. All the compounds except fensulfothion and oxydemeton-methyl induced cell-cycle delay in varying degrees. Cell-cycle delay caused by an OPP was found to be dose-dependent. Based on these data as well as others reported, it would appear that OPP which induce no SCE increase and no or slight cell-cycle delay could be considered as good candidates to substitute the pesticides that have been found to be harmful to the environment.     

Retinol (vitamin A) inhibition of dimethylnitrosamine (DMN) and diethylnitrosamine (DEN) induced sister-chromatid exchanges in V79 cells and mutations in Salmonella/microsome assays

When the Chinese hamster cell line V79 and the tester strain of Salmonella typhimurium TA100 were treated with the precarcinogens dimethylnitrosamine (DMN) or diethylnitrosamine (DEN) in the presence of S9 mix, a dose-dependent increase of sister-chromatid exchanges (SCE) in V79 cells and His+ revertants in TA100 resulted. DMN was a far more efficient SCE inducer than DEN, while DEN was a more efficient inducer of His+ revertants than DMN. Retinol (Rol) effectively inhibited DMN and DEN induced SCE in V79 cells and His+ revertants in TA100. Concurrent treatment of V79 cells with Rol at various doses and one dose of DMN or DEN in the presence of S9 mix caused a significant reduction of SCE as compared to SCE induced by DMN or DEN without Rol. Rol inhibition of DMN-induced SCE was dose-dependent. Rol was less efficient in inhibiting DEN-induced SCE, and no consistent dose-dependent inhibition was observed. At all doses, Rol significantly inhibited DMN and DEN induced mutation frequencies in TA100. At the highest dose of Rol (40 micrograms/plate), the inhibition of DMN and DEN induced His+ revertants reached about 90% and 60%, respectively. The possibility that Rol exerts its antimutagenic activities by inhibiting certain forms of the cytochrome P-450 isoenzymes required for activation of precarcinogens such as DMN and DEN is discussed.     

Induction of sister-chromatid exchanges by DNA-damaging agents and 12-O-tetradecanoyl-phorbol-13-acetate (TPA) in synchronous Chinese hamster ovary (CHO) cells

Synchronous CHO cells were obtained by mitotic selection; synchrony was maintained up to the 5th cell cycle. The mitotic cells were seeded into T-25 flasks or P-60 plastic petri dishes, and cultured for 1 h at 37 degrees C, then the cells were treated by X-ray, UV light, and mitomycin C. The cells were then cultured for 2 cell cycles with TPA and BrdUrd and sister-chromatid exchanges (SCE) analyzed by the FPG method. Following X-irradiation, the frequency of induced SCE increased linearly with dose reaching a maximum of 19.8 times the control frequency after 200 rad. With higher doses, the SCE frequency declined. In the presence of TPA, SCE frequencies were 1.8 times control levels for all X-ray doses studied (0-800 rad), the frequency seen in non-irradiated cultures treated with TPA. The induced SCE frequency also increased linearly following treatment with UVL and mitomycin C, reaching levels higher than 1.8 times controls with doses exceeding 2.5 J/m2 UVL or mitomycin C (30 min). In the presence of TPA, the SCE frequencies increased to 1.8 times controls following low UVL and mitomycin C doses, but were not influenced by TPA in the higher dose range (above 2.5 J/m2 or 10(-10) M mitomycin C. Most of the SCE were induced by X-rays during the first S phase after treatment. Following higher UVL doses (5 J/m2), however, the SCE frequency remained elevated (1.5 times controls) for 4 cell cycles after exposure.     

Comparison of baseline sister-chromatid exchanges (SCE), cyclophosphamide-, ethylnitrosourea (ENU)-induced SCE, ENU-induced cell-cycle delay and chromosome aberrations between Peru and laboratory mice

The baseline sister-chromatid exchange (SCE) frequency and sensitivity to the effects of the mutagens cyclophosphamide (CPP) and ethylnitrosourea (ENU) in bone-marrow cells of descendants of wild mice trapped from Rimac valley in Peru (Peru mice) were studied and compared to the same effects in laboratory mice. Baseline SCE of the Peru mice were significantly higher than those of the C57BL/6J and DBA/2 mice. The average SCE/cell of 4 Peru mice was 5.4 (range 3.8-7.6), while the average of SCE/cell of either 4 C57BL or 5 DBA mice was 3.2 (range 3.0-3.4). The variation of SCE/cell among Peru mice studied was statistically significant whereas among C57BL or DBA mice it was not. SCE frequencies of primary cultures derived from the ear tissue of 10 Peru (mean SCE/cell = 8.5) were also significantly higher than those of 6 C57BL mice (mean SCE/cell = 7.4). CPP treatment resulted in a dose-dependent increase of SCE frequencies in bone-marrow cells of all the mice. However, some of Peru mice treated with CPP had significantly higher SCE than the other Peru mice and than all of the C57BL and DBA mice treated with equivalent dose. ENU induced increased SCE frequencies in Peru and C57BL mice. Again some of Peru mice either had significantly higher SCE, greater extent induced cell-cycle delay or chromosome aberrations (CA) than other Peru mice and than of all the C57BL mice treated with equivalent dose.(ABSTRACT TRUNCATED AT 250 WORDS)     

Induction of sister-chromatid exchange (SCE) and cell-cycle inhibition in mouse peripheral blood B lymphocytes exposed to mutagenic carcinogens in vivo

To determine the sensitivity of the mouse peripheral blood lymphocyte (PBL) culture system, male B6C3f1 mice were injected i.p. with either 2-acetylaminofluorene (AAF) (20, 40, 80, 160 mg/kg), benzo[a]pyrene (BP) 25, 75, 150, 300 mg/kg), dichlorvos (DCV) (5, 15, 25, 35 mg/kg), ethyl methanesulfonate (EMS) (10, 30, 90, 180, 270 mg/kg), or N-nitrosomorpholine (NM) (37.5, 75, 150, 300 mg/kg) dissolved in either RPMI 1640 (DCV, EMS, NM) or sunflower oil (AAF, BP). 24 h later blood was removed by cardiac puncture, and the lymphocytes were cultured in the presence of lipopolysaccharide for analysis of SCE in B lymphocytes. All 4 mutagenic carcinogens (AAF, BP, EMS, NM) induced significant dose-related increases in SCE frequency. DCV, a potent neurotoxicant, caused no change in the baseline SCE frequency. At the highest concentration of each chemical examined, AAF caused a 1.6-fold increase, EMS a 1.8-fold increase, NM a 3.0-fold increase, and BP a 3.1-fold increase in SCE frequency compared to concurrent controls. A comparison of these results for PBLs with those reported in the literature for bone marrow cells indicates that PBLs offer a good quantitative and qualitative estimate of the SCE-inducing potential for these 5 compounds in bone marrow cells.     

Comparative study of SCE induction and cytostatic effects by homo-azasteroidal esters of N,N-bis(2-chloroethyl)aminobenzoic acid in human lymphocytes

The effect of homo-azasteroidal esters of benzoic acid mustard isomers and the 4-methyl derivatives, which have steroidal lactams as a biological basis, on cytogenetic damage was studied. Twenty compounds were comparatively studied, on a molar basis, as regards their ability to induce sister-chromatid exchanges (SCEs) and cell division delays.A correlation between potency for SCE induction, effectiveness in cell division delay and previously established antitumor activity of these compounds was observed.     

Mutagenicity of methyl 2-benzimidazolecarbamate, diethylstilbestrol and estradiol: structural chromosomal aberrations, sister-chromatid exchanges, C-mitoses, polyploidies and micronuclei

Methyl 2-benzimidazolecarbamate (MBC), diethylstilbestrol (DES) and estradiol were tested with regard to their ability to induce C-mitoses, polyploidies, micronuclei, structural chromosomal aberrations and sister-chromatid exchanges (SCE) in human peripheral lymphocytes in vitro. The compounds did not induce structural chromosomal aberrations either in the presence or absence of metabolic activation. MBC and estradiol were negative in the SCE test. DES induced SCE rates which were not even twice the control level and which were independent of dose and of metabolic activation. All compounds induced C-mitoses, polyploidies and micronuclei. The micronuclei are interpreted as resulting from errors in the anaphase distribution of chromosomes by spindle disturbances rather than from structural chromosomal aberrations.     

Bromodeoxyuridine (BrdU) template and thymodine pool effects on high frequencies of sister-chromatid exchange (SCE) in Bloom syndrome cells and a mutant cell line (AsHa) originated from ataxia telangiectasia

The effect of bromodeoxyuridine (BrdU)-substituted DNA template and thymidine (dT) pool on excess sister-chromatid exchanges (SCEs) was studied in Bloom syndrome (BS) cells and an ataxia telangiectasia (AT)-derived mutant cell line (AsHa). When BS endomitotic cells were labeled with low and high (or high and low) BrdU concentrations during S₁ and S₂, only the BrdU concentration during S₁ phase affected the observed SCE. In BS cells about a 10-fold increase in SCEs occurs during or following replication on a BrdU-substituted template (high-high and high-low BrdU labeling) relative to the normal DNA template. SCEs decreased to about half in AsHa cells labeled with various BrdU doses (40, 60, 80 and 100 μg/ml) during only S₁, compared with those labeled during S₁ and S₂. Co-cultivation of AsHa and BS cells resulted in a significant reduction in SCE level from 70 to 13–17 in BS cells, lowered the BrdU concentrations necessary for sister-chromatid differential (SCD) staining from 40 to 10 μg/ml with normal SCE level and resulted in decreased level of SCEs at high BrdU concentrations (80–100 μg/ml) 12–14 SCE) in AsHa cells, compared with the originally increased SCE level (36.65 SCE at 100 μg/ml) without co-culture. However, co-cultivation between AsHa and normal cells lowered the BrdU dose necessary for SCD staining from 40 to 30 μg/ml; the dT pool possibly balanced at this level, which is clearly higher than that at co-cultivation between AsHa and BS cells. The reason for the very high BrdU doses needed to achieve SCD would seem to be that AsHa cells have high levels of thymidylate (TMP) synthetase, which maintain a large endogenous thymidine pool. This has been confirmed by direct measurement. These findings strongly support that excess and decreased dT pools are closely related to the condition necessary for high SCE induction.     

Sister chromatid exchange (SCE) for the first time in Casertana pig breed

Lymphocyte cell cultures from 30 Casertana pigs (13 males and 17 females), reared in southern Italy, underwent the sister chromatid exchange (SCE) test. The Casertana pig is an endangered native breed from the region of Campania, raised chiefly half-wild. In the 1500 cells we studied, the mean SCE was 6.32+/-2.92 and SCE frequency did not follow a Poisson distribution. A higher mean value of SCE cell(-1) was found in the older group (SCE cell(-1)=6.68+/-2.95) compared with the younger (SCE cell(-1)=5.94+/-2.84), the difference being statistically significant (P<0.01). To our knowledge, this is the first investigation in a representative sample of Italian pig breed using the SCE test. Furthermore, this is the first report where the differences found in the mean SCE values were related to age in domestic species.     

Synthesis and mutagenicity of 2-aryl-substitute ( o -hydroxy-, m -bromo-, o -methoxy-, o -nitro-phenyl or 4-pyridyl) benzothiazole derivatives on Salmonella typhimurium and human lymphocytes exposed in vitro

Derivatives of 2-aryl-substitute (o-hydroxy-, m-bromo-, o-methoxy-, o-nitro-phenyl or 4-pyridyl) benzothiazole were synthesized and tested for their mutagenicity in in vitro assays: (i) in the Ames test with Salmonella typhimurium TA98 and TA100 strains; and (ii) in the sister chromatid exchange (SCE) in cultured human lymphocytes. The four of compounds (BT-11, B-12, BT-14 and BT-15) caused statistically significant increase in revertant colonies of TA98 and TA100. Treatment of lymphocytes with compounds also caused a significant increase in SCE/cell in association with high levels and long exposure (300 μg/mL and 48 h) of the four compounds. It can be concluded that benzothiazole derivatives showed mutagenic activity and were also able to exert a genotoxic effect reducing both the replication index and mitotic index.     

四种杀虫剂对白纹伊蚊(Aedes albopictus)细胞株(C6/36)的细胞遗传学效应

本文研究了四种杀虫剂:敌敌畏乳剂,灭害灵,甲基对硫磷,叶蝉散对白纹伊蚊细胞株（C6/36）染色体畸变和姐妹染色单体互换（SCE）的影响。结果表明:0.1％和0.01％浓度的敌敌畏,可使（SCE）频率明显增加,而染色体畸变率只在0.1％浓度有显著增加;0.5％的灭害灵,可使SCE频率明显增加,而染色体畸变增加不明显;甲基对硫磷和叶蝉散的实验结果表明,无论是染色体畸变和SCE频率均没有明显增加。     

Sister-chromatid exchanges in a special form of xeroderma pigmentosum (form II)

The frequency of sister-chromatid exchanges (SCE) was studied in peripheral blood lymphocytes from a xeroderma pigmentosum (form II, XPII) patient. The cells were irradiated with UV or X-rays. In some experiments novobiocin (NB), inhibitor of topoisomerase II, or caffeine (CA), inhibitor of DNA repair were added to the cultures. The level of spontaneous SCE in the patient's lymphocytes was found to be significantly increased in comparison to that in the cells from normal donors. The inhibitors and UV-light caused a rise in the frequency of SCE in the cells taken from normal donors and except for NB, in the lymphocytes from the patient XPII. X-Rays did not increase SCE frequency in normal lymphocytes and lowered it in the patient's cells. SCE frequency rose when inhibitors of DNA replication and repair were used in combination with mutagens.     

Sister chromatid exchange in cell lines from malignant lymphomas (lymphoma lines)

Summary The frequency of sister chromatid exchanges (SCEs) was studied in cells from three freshly established lymphoma lines, derived from two patients with Hodgkin's disease and one patient with non-Hodgkin lymphoma. These values were compared to SCE rates found in cells from two long-established lymphoma lines (Raji and BJAB) and to those recorded in control cell lines of normal human donors. The highest SCE levels were demonstrated in the freshly established lymphoma lines, the lowest SCE values separated the lymphoblastoid cell lines from healthy controls, and the older lymphoma lines Raji and BJAB presented rates in between. The influences of BUDR concentration and of the duration of BUDR treatment on the frequency of SCEs were tested. Furthermore, the dependence of the SCE rate on the time interval between establishment of the cell line and its SCE investigation was considered. The connection between elevated SCE rates and the neoplastic nature of lymphoma lines is discussed.     

Sister chromatid exchange in chromosomes of sheep (Ovis aries)

Blood lymphocyte cultures from 32 Comisana and Laticauda sheep breeds (15 males and 17 females) raised in Southern Italy were studied using sister chromatid exchange (SCE) test. Of the 932 cells studied, the SCE-mean value was 7.20 +/- 2.5 per cell for both breeds. Indeed, the SCE mean values were 7.12 +/- 2.45 and 7.28 +/- 2.55 in Comisana and Laticauda breeds, respectively, and the differences were not significant. No statistical differences were noticed between male and female cells (7.25 +/- 2.39 and 7.16 +/- 2.60, respectively). The SCE frequency distribution did not follow a Poisson distribution. The number of SCE were significantly higher than expected in chromosomes 1, 2 and 3 (p < 0.001) and significantly lower than expected in the X and remaining chromosomes (p < 0.001) on the basis of relative chromosome lengths.     

Induction of sister-chromatid exchanges in L1210 leukemia cells by new antitumor 2-haloethyl(methylsulfonyl) methanesulfonate compounds

The antitumor 2-halo(chloro, bromo, and fluoro)-ethyl(methylsulfonyl) methanesulfonates, ethyl(methylsulfonyl) methanesulfonate, and chlorozotocin, a 2-chloroethylnitrosourea, were evaluated for their potential to induce SCEs in L1210 cells. The results indicate that all the compounds induced approximately 2-fold or greater increases in SCEs in a dose-related manner. 2-Chloroethyl(methylsulfonyl) methanesulfonate, a DNA-interacting agent and a drug selected for clinical trials, exhibited the highest SCE increase in these cells.     

Genotoxicity of beryllium, gallium and antimony in short-term assays.

The genotoxicity of beryllium, gallium and antimony compounds was studied with the rec, Salmonella mutagenicity and SCE assays. In the rec assay, all the salts of the metals, BeCl2, Be(NO3)2, GaCl3, Ga(NO3)3, SbCl3, SbCl5, and an oxide, Sb2O3, had DNA-damaging activity. None of the compounds was mutagenic to Salmonella. In the SCE assays using V79 cells, 2 antimony(III) compounds, SbCl3 and Sb2O3, and 2 beryllium compounds, BeCl2 and Be(NO3)2, induced SCEs significantly. Sb2O3, slightly soluble in water, was positive in both the rec assay and the SCE assay at very low doses.     

Sister chromatid exchange (SCE) frequencies differ between directly prepared cytotrophoblasts and cultured mesenchymal core cells

Summary Analysis of sister chromatid exchange (SCE) in chorionic villus cells may become useful in measuring the response of fetal tissues to clastogens or mutagens or for prenatal diagnosis of chromosome breakage syndromes such as Bloom syndrome. Previous studies have failed to analyze cytotrophoblastic cells and mesenchymal core cells, or have found no difference between SCE frequencies in directly prepared and cultured cells. Our data indicate significant differences in SCE frequencies between the two cell types: SCE frequency in directly prepared cytotrophoblasts was 6.73 SCE/cell ± 1.6, whereas SCE frequency in cultured mesenchymal core cells was 10.31 SCE/cell ± 0.49 (P < 0.001). SCE analyses involving chorionic villi must take into account cell type.Presented at the 41st Meeting of the American Society of Human Genetics, Cincinnati, Ohio     

SCE induction in Chinese hamster ovary cells (CHO) exposed to G agents

Cultured Chinese hamster ovary (CHO) cells were exposed to two neurotoxic organophosphates, either satin (GBI, GBII) at 1.4 x 10⁻³ M or soman (GD) at 1.1 and 2.2 x 10^t-3 M for 1 h, grown and their metaphase chromosomes scored for sister-chromatid exchanges (SCE). No cytotoxicity was seen with either agent at any dose level tested. Since histograms of SCE per cell showed that they were non-symmetrically arrayed around the mean, the number of SCEs were analyzed by using the nonparametric tests, Mann-Whitney and Kruskall-Wallis. Agents GBI and GBII did not show any significant increase in SCE over baseline. On the other hand, GD demonstrated a statistically significant increase in SCE with and without metabolic activation. Ethyl methanesulfonate (EMS) alone at 5 x 10⁻³ M and cyclophosphamide (CP) at 10⁻⁴ M in the presence of rat microsomes (S9) induced a 3- and 8-fold increase in SCE per cell, respectively.     

Environmental monitoring for genotoxicity: in vivo sister chromatid exchange in the house mouse (Mus musculus)

Sister chromatid exchange (SCE) values were determined in bone marrow cells isolated from mouse (Mus musculus) femurs after injections of 5-bromo-2'-deoxyuridine (BrdU) and 5-fluorodeoxyuridine (FrdU). Male mice of C3H/J, C57BL/6J, and DBA/2 strains maintained in the laboratory gave mean SCE values of 3.42 +/- 0.07, 3.62 +/- 0.08, and 3.97 +/- 0.13, respectively. Males obtained from natural populations of southwestern Ontario had a higher mean SCE value (6.02 +/- 0.16), as did inbred males maintained in outdoor enclosures for at least 3 weeks (5.07 +/- 0.22). Wild mice housed in the laboratory for 9 months or longer had SCE values similar to laboratory bred mice (3.46 +/- 0.05). The SCE values in wild-caught mice were inversely proportional (r = -0.49) to the distance between the sites where these animals were collected and the nearest major industrial center. Based on these results, SCE analysis in mice is proposed as a possible first-line monitoring procedure for the detection of general changes in environmental genotoxicity.