Genotoxic effects of the pesticides Rubigan, Omite and Rovral in root-meristem cells of Crepis capillaris L.

Three pesticides have been studied for their genotoxicity by the use of assays in the plant Crepis capillaris, aimed at measuring chromosomal aberrations, micronuclei and sister chromosome exchange (SCE). The fungicides Rubigan 12 EC (fenarimol) and Rovral 25 Flo (iprodione) and the insecticide Omite 57 E (propargite) are all widely used nowadays. The aim of our study was to evaluate the genotoxic effects of these pesticides at concentrations corresponding to those applied in agricultural practice. In preliminary experiments we found that these concentrations do not influence cell proliferation and do not inhibit the growth of root meristems. In all experiments formulated commercial products were used. From the results we conclude that the three pesticides did not induce chromosomal aberrations as estimated by metaphase and anaphase analyses. They were also not capable to induce SCE. Rubigan did not induce micronucleus formation even at the highest concentration tested, but Omite and Rovral markedly increased micronucleus formation. The MN response depended on the sampling time and the concentration used, which showed a significant dose–response correlation (r = 0.978, P < 0.01 and r = 0.941, P < 0.01, respectively). A greater increase in micronucleus frequency was observed after Rovral treatment, where the highest concentration gave a response 8–10-fold above the negative control. Both pesticides induced high frequencies of lagging chromosomes, even after exposure to the lower test concentrations. The presence of lagging chromosomes is an indication of anti-microtubule activity of the pesticides tested. This effect was more strongly expressed after exposure to the two higher concentrations of Omite and Rovral. In this case a complete destruction of the mitotic spindle was observed, resulting in C-mitoses as well as in numerical aberrations—polyploidy and aneuploidy. The present findings suggest that Omite and Rovral at concentrations comparable to those used in practice can be regarded as potential aneugens.     

In vitro and in vivo chromosomal aberrations induced by megazol

With the re-emergence of Human African Trypanosomiasis (HAT) on the one hand, which are increasingly resistant to current therapies, and the stage-dependent effectiveness or even the prohibitive cost of these therapies on the other hand, megazol, a 5-nitroimidazole thiadiazole highly active against various trypanosomal species, was assessed for its genotoxic potential. Very little information has become available until now. Two batches of megazol were provided by two different suppliers: Far-Manguinhos, a part of the Fiocruz foundation, under the Brazilian Minister of Health, and Delphia, a French company. These two batches, obtained by different synthetic routes, were studied by means of the in vitro micronucleus assay on L5178Y mouse lymphoma cells, in its microscale version. Both batches of magazol displayed a strong genotoxic activity in this screening assay. A second batch from Delphia was then investigated by use of two tests, i.e. the in vitro metaphase analysis with human lymphocytes and the in vivo micronucleus test in rat bone-marrow. Megazol was shown to be a potent inducer of in vitro and in vivo chromosomal aberrations. Although megazol is a potent trypanocidal agent and is orally bio-available, its toxicity dictates that it should not be developed further for the treatment of HAT and Chagas disease. All development work has therefore been discontinued.     

Comparison of clastogenic effects of inorganic selenium salts in mice in vivo as related to concentrations and duration of exposure

Inorganic selenium compounds in the diet have been known to protect against cancer in laboratory animals, but were harmful in high concentrations. In the present work, the relative effects of two salts, sodium selenite and sodium selenate, administered to mice in vivo, in different concentrations and durations of exposure, were compared. Aqueous solutions of each salt (7, 14, 21 and 28 mg Kg^–1 bw) were fed by gavaging to mice matched in age and sex. The animals were sacrificed at intervals of 6, 12, 18 and 24 h and chromosome preparations were made following the usual schedule of colchicine-hypotonic-fixative-airdrying-Giemsa staining. The endpoints screened were chromosomal aberrations (CA) and damaged cells (DC). Both salts affected chromosome structure and spindle formation, sodium selenite being more cytotoxic than sodium selenate. The frequencies of aberrations induced were directly proportional to the concentrations used and duration of exposure.     

石油化学工人的细胞遗传学研究——Ⅰ.染色体畸变的检测

对石油化工企业工人(180人)及非石化企业对照人群(180人)进行染色体畸变的检测,结果表明:(1)石化地区居民染色体畸变频率略高于非石化地区居民,但无显著性差异。(2)石化企业中,炼油厂污水处理车间和塑料厂污水处理车间工人的染色体畸变各项指标和对照组比较(除塑料厂污水处理车间工人的染色体畸变一项指标外)或与其它4个车间(苯酚丙酮、催化裂化、乙二醇和丁二烯)比较,都有显著或极显著的升高。4个车间分别和对照组比较,没有显著升高。(3)染色体畸变频率有季节变化,春秋季明显高于冬季和夏季。(4)对照个体中,不同性别、不同年龄组及吸烟与否,对染色体畸变的各项指标均无显著性差异。但在石化企业不同年龄工人染色体畸变率的比较中,大于或等于40岁的工人组,明显高于30岁以下各组。     

Non random distribution of lesions induced by deoxyribonuclease I in human chromosomes

We studied the action of deoxyribonuclease I on human lymphocytes in order to determine the localization of the DNAase induced aberrations. Our results indicate a non-random distribution of the lesions on chromosome regions which may reflect a differential pattern of sensitivity to the enzyme. Furthermore we observed a correspondence between the preferential DNAase induced breaks and fragile sites that are expressed in lymphocytes maintained in medium without folic acid. A possible interpretation of our findings is that the accessibility to DNAase and/or the efficiency of the repair systems depend on the chromatin structure that influences also the expression of some common fragile sites.Abbreviations DNAase I deoxyribonuclease I E.C.3.1.4.5.     

Chromosome damage induced by artificial seed aging in barley

Summary Barley (Hordeum vulgare L. Himalaya) seeds were artificially aged under two storage conditions (32 °C/12% moisture content (m.c.) and 38 °C/18% m.c.) to study the behavior of induced chromosomal aberrations during plant growth. The frequencies of aberrant anaphases at first mitosis in root tips were correlated with loss of germinability. However, after 3 and 5 weeks' growth, aberration frequency declined. In plants grown from artificially aged seeds, the frequency of aberrant anaphases appeared to be stabilized at about 1% after 5 weeks' growth, in spite of the large differences in the frequencies at first mitosis. This suggests that because of their genetic imbalance, cells with chromosomal aberrations induced by seed aging were being excluded during plant growth. Meiotic chromosome configurations at MI were normal (7 II) in all plants studied, although a few precocious separations were found. Meiotic aberrations were found at AI-TI, AII-TII and the tetrad stages in the pollen mother cells of plants grown from the control and artificially aged seeds. However, there were no clear differences among the control and the two aging treatments. It was obvious that some cells with meiotic chromosomal aberrations were lost between the AI-TI and AII-TII stages, and still more between the AII-TII and tetrad stages. The frequency of tetrads with micronuclei in plants produced from artificially aged seeds was the same as in the control. The plants grown from artificially aged seeds showed high pollen fertility (95.2 to 97.0%) and seed fertility (90.1 to 97.2%) which was comparable to the control values (97.4 and 97.9%) respectively, indicating no special effects of seed aging. Anaphase cells of the first mitosis in the next (A₂) generation were analyzed to study the transmission of chromosomal aberrations through mitotic and meiotic cell divisions in the A₁ generation. Aberrant anaphases in the progeny from the artificially aged seeds were not higher than those of the control progeny. This indicates that the chromosomal aberrations induced by seed aging are not transmitted to the next generation.Published with the approval of the Director of the Colorado state Experiment Station as Scientific Series No. 2776     

The cytogenetic and hepatotoxic effects of dioxin on mouse liver cells

The cytogenetic and hepatotoxic effects of 2,3,7,8-tetrachlorodibenzo p-dioxin (TCDD) on mouse liver cells were investigated. Male C57BL/6J strain mice, which have TCDD receptors, were given single intraperitoneal injections of 25, 37.5, 75 and 150 g of TCDD/kg body weight or corn oil carrier alone. Two-thirds hepatectomies were carried out at 1 or 7 days after injection and chromosomal aberrations and mitotic indexes of the regenerating hepatocytes were scored 54 hr after hepatectomy. Liver sections from additional intact mice were studied for TCDD-hepatotoxicity at 1, 7 and 30 days after injection. The three high doses of TCDD caused hepatotoxicity with necrosis of liver cells and focal architectural collapse by 30 days after injection. No evidence was obtained of an increase in the frequency of chromosomal structural aberrations at doses that allowed sufficient mitotic activity for cytogenetic evaluation. We conclude that TCDD is not a clastogen for mouse hepatocytes, although high doses cause marked hepatocellular necrosis.Abbreviations CSD chromosome deletion - META metacentric chromosome - TCDD 2,3,7,8-tetrachlorobenzo-p-dioxin     

微核形成与细胞周期关系的初步研究 Ⅲ.丝裂霉素c诱发人淋巴细胞染色体畸变与不同周期阶段的微核形成

为了研究染色体畸变与微核形成的关系,本实验用不同浓度的丝裂霉素C(MMC,0.025—0.4μg/ml),处理人外周血淋巴细胞,观察中期染色体畸变与不同细胞周期形成的微核间的关系。获得如下主要结果:(1)MMC诱发的染色体畸变细胞率(ACF),未经培养的G_0期淋巴细胞的微核细胞率(NC-MNCF)以及培养的淋巴细胞的微核细胞率(C-MNCF),在一定剂量范围内均呈剂量依赖性增加,并可用幂回归方程描述;(2)微核形成与染色体畸变全然无关的NC-MNCF,和C-MNCF一样,与ACF呈良好的正相关;(3)用胞质分裂阻滞(CB)法,检测MMC诱发的CB-MNCF,较C-MNCF无显著提高,MNCF/ACF的比值较小,并随着MMC剂量增加从0.15左右降到0.03。所有上述结果表明,不能简单理解微核形成与染色体畸变间的关系,在分裂的细胞群体中,中期染色体畸变可能仅是微核形成的一种来源。     

Increased frequency of chromatid breaks in lymphocytes of heterozygotes of ataxia telangiectasia after in vitro treatment with caffeine

The frequencies of caffeine-induced chromosomal aberrations (CA), mainly chromatid (CdB) and chromosome (CB) breaks, were studied in lymphocyte cultures derived from 6 obligatory heterozygotes and 1 homozygote of ataxia telangiectasia (AT), and from 4 control adult healthy persons. Caffeine (CF, 1 mM) was added at the beginning of the cultures exposed to CF the frequency of CB was 1.9% and of CdB 1.3%. In cells of the AT homozygote, the frequency of CdB was 6.8% in the absence and 8.7% in the presence of caffeine, the frequencies of CB being 3.4 and 10.9%, respectively. In AT heterozygous cells treated with CF, CdB increased 13-fold as compared to a less than 3-fold increase in control cells. Comparing the frequencies of CF-induced chromosomal lesions in control and AT heterozygous cells, potentiation factors (Pf) for the effect of 1 AT gene on cell sensitivity of CF (Pf [AT]) were 3.5 for CB, 6.6 for CdB and 5.5 for CA. These data demonstrate that lymphocytes of AT heterozygotes are significantly more sensitive to caffeine treatment in vitro in terms of increased frequency of CdB than normala cells, which may be useful for the diagnosis of carriers of this defective gene.     

The use of multiple sampling times in in vitro chromosome assays

Asynchronously growing V79 hamster cells were treated with hypotonic solutions of different osmolalities, with ethyl methanesulfonate (EMS) or a combination of these 2 agents. Four different fixation times (8, 10, 14, 18 h) were tested. Hypotonic treatment alone induced chromosomal aberrations (CA), leading to very high frequencies at low osmolalities (50 mOsm/kg H₂O). EMS also induced CA, but a comparison of EMS and hypotonicity revealed that EMS induced fewer aberrations at teh maximum doses tested. A combined treatment produced contradictory results, depending on the sampling time: 8 and 14 h led to a clear elevation of EMS-induced CA by hypotonicity, 10- and 18-h sampling times led to a decrease in the aberration frequency in EMS and hypotonically treated cells.

The observation that the choice of sampling time significantly influences the incidence of chromosomal aberrations is of particular interest for in vitro assays. In this study the 4 different sampling times are not enough to allow meaningful conclusions about additive or synergistic effects of the mutagens tested. These contradictory results are caused, on the one hand, by the very steep dose-response curve after hypotonic treatment and on the other hand by the varying degree of cell-cycle delay after combination treatment. This makes a valid comparison of teh CA frequencies impossible because no 2 sampling times contain the same mixture of cells.     

近视散光眼在自然扩瞳和药物散瞳后波面像差的研究

目的 :讨论近视散光眼人群在暗室自然扩瞳和使用药物散瞳后所得到波面像差的差别。方法 :使用基于Shack Hartmann原理设计的COAS(completeophthalmicanalysissystem)波面像差仪检查 6 2只眼 ,分别在暗室自然扩瞳和通过滴加美多丽 P散瞳液后的波面像差。并使用COAS波面像差仪自带软件分别计算在三个分析瞳孔尺寸下的二～六阶像差系数。运用双因素方差分析 (twowayANOVA)方法研究各阶均方根 (rootmeansquare ,RMS)和各种类型像差在药物作用和分析瞳孔尺寸这两个因素影响下的变化是否具有显著性 ,同时考虑二因素的交互作用。结果 :药物散瞳对二、三阶像差均方根的影响没有显著意义 (P >0 .10 ) ,但在测量更高阶像差———四、五、六阶时 ,与暗室自然扩瞳所得波面像差的差异具有显著性意义 ;虽然不同瞳孔尺寸对各阶波面像差均方根变化具有显著意义 (P <0 .0 1) ,但对研究药物散瞳对波面像差的影响无显著意义 (P >0 .10 )。结论 :药物散瞳与暗室自然扩瞳在高阶像差测量时的差异均有显著意义 ,临床上建议尽量使用暗室自然扩瞳     

Clastogenic effect of ethanol in chronic and abstinent alcoholics

Alcoholism is one of the main causes of damage for human health, being relevant to study the induction of chromosomal aberrations (CA) by ethanol, and to investigate the individual susceptibility to diseases caused by alcoholism. A cytogenetic study was performed in human peripheral blood lymphocytes of 29 heavy chronic alcoholics, 11 alcoholics in abstinence, and 10 controls. The values of the chromosomal aberrations, mitotic indexes (MI) and proliferation indexes (PI) were determined. A molecular cytogenetic study was also carried out using fluorescence in situ hybridization (FISH) method with DNA library probes for chromosomes 1, 3 and 6, in lymphocytes from chronic alcoholic individuals in comparison with a control group. The results showed that the CA frequencies for chronic alcoholics (5.15 CA/100 cells) and alcoholics in abstinence (3.87 CA/100 cells) were higher than those obtained for control individuals (1.72 CA/100 cells). The mean translocation frequencies (equivalent to the genome) were calculated for six chronic alcoholics (0.267 translocations/100 cells) and six alcoholics in abstinence (0.167 translocations/100 cells), whose values were significantly higher than those observed for six control individuals (0.067 translocations/100 cells). The CA frequencies were not statistically different when smoker and non-smoker alcoholics were compared, indicating that although the smoking habit had significantly increased (four-fold) the CA frequency in healthy control individuals, a lack of interaction effect was observed within the group of alcoholics when smokers and non-smokers were compared. The CA frequencies presented by alcoholics in abstinence were similar to those obtained for chronic alcoholics. Therefore, chronic ethanol intoxication can lead to chromosome damage and disturbances in the metabolism of endogenous and exogenous compounds, which may persist for a long time, and constitute a relevant factor of risk for the development of neoplasias.     

Induction of chromosomal aberrations in human lymphocytes by the antitumour alkylating agent homo-aza-steroidal ester of p-bis(2-chloroethyl)aminophenoxy acetic acid, in vitro

The clastogenic activity of the antineoplastic alkylating agent 3β-hydroxy-13-amino-13,17-seco-5-androstan-17-oic- 13,17-lactam-p-bis (2-chloroethyl) aminophenoxy acetic acid (NSC 294859) and its congeners was studied in human lymphocyte cultures in vitro. Cells were exposed to several concentrations of the drugs for 24 h. It was found that NSC 294859 reduces the mitotic index and causes chromosome- as well as chromatid-type aberrations in a dose-dependent way. From its congeners, the alkylating agent (p-bis (2-chloroethyl) aminophenoxy acetic acid) induces the same phenomena but to a lesser extent, while the modified steroid (3β-hydroxy-13-amino-13,17-seco-5-androstan-17-oic-13,17-lactam) causes cytogenetic damages at the control level. These results favour the assumption that the antitumor activity of NSC 294859 is mainly based on its cytogenetic effects.     

Modifying effect of iron on lead-induced clastogenicity in mouse bone marrow cells

Essential trace elements such as iron (Fe) are known to interact with nonessential metals like lead (Pb), influencing its metabolism. Ferric chloride and lead nitrate were administered intraperitoneally to Swiss albino miceMus musculus singly and successively, with or without a time gap of 1 h, to study the degree of protection, if any, afforded by iron against the clastogenic effects induced by Pb in bone marrow cells. A decrease in the frequency of lead-induced chromosomal aberrations was observed when Fe was given together with or prior to Pb administration.     

Adaptive response in irradiated human lymphocytes: radiobiological and genetical aspects

The adaptive response (AR) in human lymphocytes in different experimental protocols was investigated. The AR was found to be present in cells pre-exposed to 3 cGy of X-rays in G0, G1 and S phase as well as with tritiated water (4 muCi/ml) when the 'challenge' dose was given in G2. There was no AR after prior exposure of the cells in S phase to secondary irradiation from 70 GeV protons. The AR was not observed after preliminary X-irradiation of the lymphocytes in G0 and G1 and 'challenge' irradiation in G1. Cells from 6 patients with Down's syndrome were tested. At least 5 of them did not show the AR. The AR is considered to be a phenomenon of the antimutagenic aftereffect.     

Chromosomal alterations in cell lines derived from mouse rhabdomyosarcomas induced by crystalline nickel sulfide

Summary Prior studies have shown a preferential decondensation (or fragmentation) of the heterochromatic long arm of the X chromosome of Chinese hamster ovary cells when treated with carcinogenic crystalline NiS particles (crNiS). In this report, we show that the heterochromatic regions of mouse chromosomes are also more frequently involved in aberrations than euchromatic regions, although the heterochromatin in mouse cells is restricted to centromeric regions. We also present the karyotypic analyses of four cell lines derived from tumors induced by leg muscle injections of crystalline nickel sulfide which have been analyzed to determine whether heterochromatic chromosomal regions are preferentially altered in the transformed genotypes. Common to all cell lines was the presence of minichromosomes, which are acrocentric chromosomes smaller than chromosome 19, normally the smallest chromosome of the mouse karyotype. The minichromosomes were present in a majority of cells of each line although the morphology of this extra chromosome varied significantly among the cell lines. C-banding revealed the presence of centromeric DNA and thus these minichromosomes may be the result of chromosome breaks at or near the centromere. In three of the four lines a marker chromosome could be identified as a rearrangement between two chromosomes. In the fourth cell line a rearranged chromosome was present in only 15% of the cells and was not studied in detail. One of the three major marker chromosomes resulted from a centromeric fusion of chromosome 4 while another appeared to be an interchange involving the centromere of chromosome 2 and possibly the telomeric region of chromosome 17. The third marker chromosome involves a rearrangement between chromosome 4 near the telomeric region and what appears to be the centromeric region of chromosome 19. Thus, in these three major marker chromosomes centromeric heterochromatic DNA is clearly implicated in two of the rearrangements and less clearly in the third. The involvement of centromeric DNA in the formation of even two of four markers is consistent with the previously observed preference in the site of action of crNiS for heterochromatic DNA during the early stages of carcinogenesis.     

Hypersensitivity of lymphoblastoid lines derived from ataxia telangiectasia patients to the induction of chromosomal aberrations by etoposide (VP-16)

Mammalian DNA topoisomerase II represents the cellular target of many antitumor drugs, such as epipodophyllotoxin VP-16 (etoposide). The mechanism by which VP-16 exerts its cytotoxic and antineoplastic actions has not yet been firmly established, although the unique correlation between sensitivity to ionizing radiation and to topoisomerase II inhibitors suggest the involvement of DNA double-strand breaks. In the present study we analyzed the chromosomal sensitivity of lymphoblastoid cell lines derived from ataxia telangiectasia (AT) patients to low concentrations of the drug. Our results indicate that AT derived cells are hypersensitive to the clastogenic activity of VP-16 either when the drug is present for the whole duration of the cell cycle or specifically in the G2 phase, confirming that the induction of DNA double strand breaks, to which AT cells seem typically sensitive, could have an important role in the biological activity of VP-16.     

Frequencies of chromosome aberrations in a control population determined by G banding

Control data on chromosome aberration frequencies determined by G banding from several studies undertaken in this laboratory have been re-analysed in relation to age and smoking. The combined study group comprised a total of 162 men (90 non-smokers and 72 smokers) with ages ranging from 20 to 72 years. For the group as a whole, significant increases were observed in translocations and all symmetrical exchanges with increasing age and also when smokers were compared with non-smokers.     

河南地区新生儿染色体畸变的流行病学调查

为了解河南地区群体染色体畸变发病率情况,研究可能与染色体畸变有关的 因素及再现风险。综合运用多种现代细胞遗传学技术对3068例新生儿进行染色体核型分析,并对染色体核型异常者进行家系分析、再现风险及病例对照研究。结果表明:河南地区新生儿染色体畸变发生率为2.74%;其中13.1%由亲代遗传,86.9%为子代新生突变;病例组84例中有46例再次生育,再现染色体畸变8例,染色体畸变再发生率为17.39%;孕妇高龄、异常妊娠史、妊娠期间致畸因素接触史及胎儿宫内发育迟缓等可能是新生儿染色体畸变的高危因素。 Abstract:To investigate the incidence of chromosomal aberrations and recurrence risk in Henan and inqure into the risk factors resulting in newborn chromosomal aberrations,3 068 newbors were karyotyped with several advanced cytogenetic methods.The result showed the incidence of chromosomal aberrations was 2.74%(84cases),only 13.1% out of 84 aberrations were transmitted from the previous generation and 86.9% arose de novo.Within 46 second babies being born after their sibling with chromosomal aberrations,8 were abnormal karyotypes,the recurrence rate was 17.39%.The case-control study showed mothers with advanced age,mothers exposure to detrimental factors in pregancy and mothers with abnormal reproductive histories,intranter growth retardation may be the risk factors resulting in chromosomal aberrations.     

Chromosomal aberrations in peripheral lymphocytes from healthy subjects as detected in first cell division

Baseline frequencies of chromosomal aberrations were analysed in human peripheral lymphocytes and the influence of age, sex and smoking habits was considered. From 53 healthy subjects (29 males, 24 females) 54,689 exclusively first division cells (M1) were scored. The frequencies of chromosome aberrations per 1000 cells were 1.15±0.15 dicentrics (dic), 2.6±0.3 excess acentric fragments (ace) and 7.0±0.6 chromatid breaks (crb). An age dependency could only be established for ace. Between males and females no differences in any of the aberration types were observed. For heavy smokers (>30 cigarettes per day) a significant increase was only found for dic (2.5±0.6 per 1000 cells). Dicentric frequency was compared with background levels of other studies in which results were reported also from exclusively M1 cells. Despite cell cycle control, differences between laboratories can be observed which may be partly influenced by environmental conditions. But on the other hand the mean frequency of dic (excluding heavy smokers) of 0.95 per 1000 cells reported here is consistent for more than one decade. Since such a consistency of the mean frequency of dic is reported also from another laboratory, the conclusion is drawn that especially for the detection of low-level exposures, each laboratory should establish its own base line data, otherwise, the interpretation of the findings is dependent on the selected background level from the literature.