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Punica granatum L. (Punicaceae) whole fruit extracts, have been used in Cuban traditional medicine as an effective drug for the treatment of respiratory diseases. This species showed interesting anti-viral activity, e.g. aqueous or hydroalcoholic extracts of whole fruits have proved highly active against the influenza virus. However, some toxic properties of this extract have also been reported and, to date, very little is known about its genotoxic properties. In the present study, the genotoxicity of a Punica granatum (pomegranate) whole fruit extract was assessed using different in vitro and in vivo assays that detect DNA damage at different expression levels. Results from reversion and gene-conversion test in microorganisms, sister chromatid exchanges, micronuclei and sperm-shape abnormality assays in mice, clearly showed that the hydroalcoholic extract of P. granatum whole fruits is genotoxic when tested both in vitro and in vivo.

The aneuploidy-inducing activity of alachlor and dichlorvos, two pesticides representing an important source of human exposure to potential carcinogens, has been evaluated in a cytokinesis block micronucleus assay combined with anti-kinetochore (CREST) staining to detect chromosome loss and in situ hybridization with chromosome-specific centromeric probes for the analysis of non-disjunction. Cytofluorimetric analysis to assess potential interference of the chemicals with cell cycle progression and TUNEL assay to detect apoptosis were also performed. The results obtained show that both environmental compounds induced significant and dose-related increases of total micronuclei (MN) and CREST-positive MN as compared with the concurrent solvent control. The chemicals were also capable of promoting chromosome non-disjunction. However, the two pesticides differed in their mode of action: alachlor induced both chromosomal aberrations and aneuploidy, while the genotoxic activity of dichlorvos was only related to aneuploidy induction. Cytofluorimetric analyses showed that dichlorvos caused a marked accumulation of cells in the G 2 /M phase of cell cycle and indicate a potential for this chemical to interfere with mitosis. Furthermore, dichlorvos induced CREST-positive MN at a concentration lower than the one producing apoptosis, suggesting that dichlorvos-induced aneuploid cells may persist in the growing cell population.

Resveratrol (3,5,4′-trihydroxystilbene) is a natural occurring molecule, synthesized by plants in response to different stresses. Recent literature data seem to converge in indicating Resveratrol as an agent possessing protective effects against oxidative stresses through different mechanisms. Furthermore conflicting data are present in relation to its activity of free radical scavenger. Here we studied the antioxidant activity actually exerted by the agent against reactive oxygen species induced by H 2 O 2 treatments in CHO cells. Our attention has been focused on two major potential mechanisms: scavenging activity and interference with oxidative metabolism, by the analysis of three important targets: intracellular oxidation (Dichlorofluorescein Test), primary DNA damage (Comet Assay) and fixed DNA damage (chromosomal aberrations). Cells were treated with a single H 2 O 2 dose (2×10 −4 M) in order to induce Reactive Oxygen Species and than challenged with Resveratrol to test its ability in modulating damage. Two experimental protocols have been applied: (i) simultaneous treatment and (ii) a 3 h Resveratrol pre-treatment. In our experimental conditions Resveratrol does not appear able, ‘per se’, to induce primary DNA damage whereas a slight increase in endogenous oxidation and chromosomal aberrations at the highest dose have to be noticed. In combined treatments the molecule appears to differently affect primary and fixed DNA damage.

The relationship between G 2 -phase checkpoint activation, cytoplasmic cyclin-B accumulation and nuclear phosphorylation of p34 C D C 2 was studied in Nijmegen breakage syndrome cells treated with DNA damaging agents. Experiments were performed on lymphoblastoid cell lines from four Nijmegen breakage syndrome patients with different mutations, as well as on cells from an ataxia telangiectasia patient. Lymphoblastoid cell lines were irradiated with 0.50-2 Gy X-rays and the percentage of G 2 -phase accumulated cells was evaluated by means of flow cytometry in samples that were harvested 24 h later. The G 2 -checkpoint activation was analysed by scoring the mitotic index at 2 and 4 h after treatment with 0.5 and 1 Gy X-rays and treatment with the DNA double-strand break inducer calicheamicin-yl. Cytoplasmic accumulation of cyclin-B was evaluated by means of fluorescence immunostaining or Western blotting, in cells harvested shortly after irradiation with 1 and 2 Gy. The extent of tyrosine 15-phosphorylated p34 C D C 2 was assessed in the nuclear fractions. Nijmegen breakage syndrome cells showed suboptimal G 2 -phase checkpoint activation respect to normal cells and were greatly different from ataxia telangiectasia cells. Increased cytoplasmic cyclin-B 1 accumulation was detected by both immunofluorescence and immunoblot in normal as well as in Nijmegen breakage syndrome cells. Furthermore, nuclear p34 C D C 2 . phosphorylation was detected at a higher level in Nijmegen breakage syndrome than in ataxia telangiectasia cells. In conclusion, our data do not suggest that failure to activate checkpoints plays a major role in the radiosensitivity of Nijmegen breakage syndrome cells.

Naturally occurring antioxidants are extensively studied for their capacity to protect organisms and cells from damage induced by oxygen reactive species. In fact, oxidative stress is considered a cause of aging, degenerative disease and cancer. We have focused our attention on two agents, ascorbic acid and β-carotene, commonly considered to be antioxidants, but whose protective activity against cancer is insufficiently known. This paper reports on the ability of these agents to act against damage induced by H 2 O 2 and bleomycin, in Chinese hamster ovary cells cultivated in vitro. Cytogenetic and cytofluorimetric analyses were performed. Both vitamins proved effective in reducing H 2 O 2 .induced sister chromatid exchanges, but increased H 2 O 2 . and bleomycin-induced chromosomal aberrations. Cytofluorimetric data, in contrast, showed that ascorbic acid and β-carotene act as scavengers of endogeneous and H 2 O 2 -induced oxygen species.

The relationship between chromosomal breakage and perturbations of cell cycle progression was investigated in lymphoblastoid cell lines established from a healthy donor, two subjects affected by Nijmegen Breakage Syndrome (NBS) and an ataxia-telangiectasia (AT) patient. The cytogenetic analysis revealed a similar chromosomal hypersensitivity in both NBS and AT cells exposed in the G1 phase to 200 cGy X-rays or in G2 to 15-30 cGy. Similarly, no differences were observed in the frequency of chromatid-type aberrations induced in G2 by 1-2 pg/ml calicheamicin gamma 1I, a DNA double-strand break inducer. In addition, as observed in AT cells, the rate of G2 radiation-induced chromosomal damage was less enhanced in NBS than in control cells following 3-h incubation with inhibitors of DNA synthesis/repair (cytosine arabinoside, aphidicolin, DMSO, hydroxyurea, caffeine). This is suggestive of an altered DNA lesion-processing pathway common to both syndromes. Despite the close resemblance of cellular phenotypes in the two syndromes, the analysis of mitotic indices carried out at 2 and 4 h postirradiation indicated that NBS sustained a G2-delay greater than that observed in AT cells, Furthermore, the flow cytometric analysis of 50-300 cGy irradiated cells at 10 and 20 h before harvesting showed that NBS cells sustained a G2/M phase arrest markedly lower than AT cells. Our data indicate that NBS and AT gene products are involved in a common pathway of radiation-induced chromosomal damage, but in a different one for cell cycle control after irradiation.

Background radiation is likely to constitute one of the factors involved in biological evolution since radiations are able to affect biological processes. Therefore, it is possible to hypothesize that organisms are adapted to environmental background radiation and that this adaptation could increase their ability to respond to the harmful effects of ionizing radiations. In fact, adaptive responses to alkylating agents and to low doses of ionizing radiation have been found in many organisms. In order to test for effects of adaptation, cell susceptibility to treatments with high doses of radiomimetic chemical agents has been studied by growing them in a reduced environmental radiation background. The experiment has been performed by culturing yeast cells (Saccharomyces cerevisiae D7) in parallel in a standard background environment and in the underground Gran Sasso National Laboratory, with reduced environmental background radiation. After a conditioning period, yeast cells were exposed to recombinogenic doses of methyl methanesulfonate. The yeast cells grown in the Gran Sasso Laboratory showed a higher frequency of radiomimetic induced recombination as compared to those grown in the standard environment. This suggests that environmental radiation may act as a conditioning agent.

Spontaneous frequencies of sister chromatid exchanges (SCEs) and SCEs induced in vitro by chemicals with different mechanisms of action such as mitomycin C, 4-nitroquinoline oxide, and 3-aminobenzamide were examined in phytohemagglutinin-stimulated peripheral blood lymphocytes from a group of workers in a rubber plant and a control group, both of which had been analyzed for levels of spontaneous SCEs 2 years earlier. An interindividual variability in the induction of SCEs was found after in vitro treatments with the different mutagens, which did not correlate with occupational exposure. This variability in the sensitivity to the induction of SCEs might be correlated to genetic differences among individuals, which have to be taken into account in environmental monitoring programs.

Many studies in human and mammalian cells have shown the involvement of resveratrol in the modulation of several biological processes, including the regulation of carcinogenesis. However, the molecular mechanisms underlying its antitumorigenic activity are still not defined. There is great interest in developing new agents that can modify the efficacy of radiation therapy. The aim of the present study was to investigate the cellular response to treatments with X rays and resveratrol, alone or in combination, in terms of DNA damage, cell cycle delays and induction of apoptosis. Lymphoblastoid cells AHH-1 were treated and analysed at successive sampling times in order to study the induction of DNA breaks using the Comet assay and the induction of apoptosis and cell cycle modulation through cytofluorimetric analysis. Our results suggest that resveratrol causes the induction of apoptosis and a block of cell cycle progression at an early step of S-phase. Furthermore, resveratrol mitigates the apoptotic clearance of irradiated cells and prevents the G 2 phase cell cycle arrest induced by X-rays.

Oxidative stress due to oxygen and various radical species is associated with the induction of DNA single- and double-strand breaks and is considered to be a first step in several human degenerative diseases, cancer and ageing. Naturally occurring antioxidants are being extensively analysed for their ability to protect DNA against such injury. We studied three naturally occuring compounds, Ascorbic Acid, Melatonin and Ellagic acid, for their ability to modulate DNA damage produced by two strong radical oxygen inducers (H2O2 and Bleomycin) in cultured CHO cells. The alkaline Comet assay was used to measure DNA damage and a cytofluorimetric analysis was performed to reveal the intracellular oxidative species. The data showed a marked reduction of H2O2- and Bleomycin-induced DNA damage exerted by Ellagic Acid. On the contrary Ascorbic acid and Melatonin appeared to induce a slight increase in DNA damage per se. In combined treatments, they caused a slight reduction of H2O2-induced damage, but they did not efficiently modulate the Bleomycin-induced one. The Dichlorofluorescein diacetate (DCFH-DA) cytofluorimetric test confirmed the strong scavenging action exerted by Ellagic Acid.

Aflatoxin B1 is a mycotoxin produced by Aspergillus flavus and Aspergillus parasiticum, which may be present as a food contaminant. It is known to cause acute toxic effects and act as a carcinogenic agent. The carcinogenic action has been related to its ability to form unstable adducts with DNA, which represent possible mutagenic sites. On the other hand, the primary cellular target responsible for its toxic action has not yet been clearly identified. Previous data suggested a possible correlation between cell proliferation and responsiveness to aflatoxin toxicity. These observations led us to investigate the effect of the toxin on cell cycle progression of three human cell lines (HepG2, SK-N-MC and SK-N-SH derived from liver and nervous tissue tumours); they were shown to display different responses to toxin exposure and have different growth kinetics. We performed analysis of the cell cycle, DNA synthesis and expression of p21 and p53 in the presence and absence of the toxin in all cell lines exposed. The results of cell cycle cytofluorometric analysis show significant alterations of cell cycle progression as a result of toxin treatment. In all cell lines exposure to a 24 h toxin treatment causes a dose-dependent accumulation in S phase, however, the ability to recover from impairment to traverse S phase varies in the cell lines under study. SK-N-MC cells appear more prone to resume DNA synthesis when the toxin is removed, while the other two cell lines maintain a significant inhibition of DNA synthesis, as indicated by cytofluorimetry and [(3)H]dTR incorporation. The level of p53 and p21 expression in the three cell lines was examined by western blot analysis and significant differences were detected. The ready resumption of DNA synthesis displayed by SK-N-MC cells could possibly be related to the absence of p53 control of cell cycle progression.

We have previously characterized a Saccharomyces cerevisiae mutant which contains a mutation in the essential rpn11/mpr1 gene coding for the proteasomal regulatory subunit Rpn11. The mpr1-1 mutation shows the phenotypic characteristics generally associated with proteasomal mutations, such as cell cycle defects and accumulation of polyubiquitinated proteins. However, for the first time, mitochondrial defects have also been found to be a consequence of a mutation in a proteasomal gene (Mol. Biol. Cell 9 (1998) 2917-2931). Since the mutant strain is thermosensitive both on glucose and on glycerol, we searched for revertants in order to shed light on the Rpn11/Mpr1 functions. Spontaneous revertants able to grow on glucose but not on glycerol at 36 degrees C were isolated, and, only from them, revertants able to grow at 36 degrees C on glycerol were selected. Revertants of the two classes were found to be extragenic. The detailed characterization of these extragenic suppressors demonstrates that the phenotypes related to cell cycle defects can be dissociated from those concerned with mitochondrial organization.

Editor—Nijmegen breakage syndrome (NBS) is a rare autosomal recessive disorder, characterised by microcephaly, bird-like face, growth retardation, immunodeficiency, cytogenetic abnormalities, increased radiosensitivity, and high susceptibility to lymphoid malignancy. The NBS1 gene, mapped on chromosome 8q211 and recently cloned,2 3codes for nibrin, a member of the hMre11/hRAD50 protein complex, involved in DNA double strand break repair. The NBS Registry in Nijmegen includes 55 patients. The majority of them are of eastern European origin and share a common haplotype, suggesting a founder effect, and a mutation consisting of a truncating 5 bp deletion in exon 6, 657-661 del ACAAA.4 Five further mutations have been found in six patients with different haplotypes and of various ethnic origins. We found a new mutation of the NBS1 gene in a 2 year old girl from Morocco. The patient, a girl born at term in August 1997 (fig 1), is the third child of apparently non-consanguineous parents; the two brothers, aged 12 and 6 years, are healthy. The pregnancy was uneventful until the 33rd week, when growth retardation, dilatation of the cerebral ventricles, and agenesis of the corpus callosum was diagnosed by ultrasound examination. Figure 1 (A) The patient at 18 months. (B) The right hand with preaxial polydactyly. Birth weight was 2520 g (3rd centile), length 46 cm (

In a program coordinated by the Italian Ministry of Works, we tested in vitro four pesticides widely employed in a developed agricultural region of central Italy. The four commercial agents were chosen on the basis of their diffusion in agricultural practice, knowledge of their active principle(s), and scant availability of data concerning their toxic and genotoxic activity. The agents were Cirtoxin, Decis, Tramat Combi (TC), and Lasso Micromix (LM). All substances were tested in three in vitro systems: Chinese hamster ovary (CHO) cells, a metabolically competent hamster cell line (Chinese hamster epithelial liver; CHEL), and root tips of Vicia faba (VF). The cytotoxic and genotoxic end points challenged were micronuclei and root tip length (RTL) in VF and mitotic index (MI), proliferation index (PI), cell survival (CS), cell growth (CG), cell cycle length (CCL), sister chromatid exchanges, chromosomal aberrations, and single-cell gel electrophoresis, or comet assay, in CHEL and CHO cells. Tested doses ranged from the field dose up to 200× the field dose to take into account accumulation effects. On the whole, tested agents appear to induce genotoxic damage only at subtoxic or toxic doses, indicating a low clastogenic risk. MI, PI, CS, CG, RTL, and CCL appear to be the less sensitive end points, showing no effects in the presence of a clear positive response in some or all of the other tests. Using cytogenetic tests, we obtained positive results for TC and LM treatments in CHO but not in CHEL cells. These data could be accounted for by postulating a detoxifying activity exerted by this cell line. However, cytogenetic end points appear to be more sensitive than those referring to cytotoxicity.

Melatonin, the pineal gland hormone known for its ability to modulate circadian rhythm, has recently been studied in its several functions. It is believed to inhibit cancer growth, to stimulate the immune system and to act as an antioxidant. In particular, this latter activity is ascribed to two different mechanisms: stimulation of radical detoxifying enzymes and scavenging of free radicals. We used this compound in mammalian cells in vitro to investigate its mechanism of action in modulating DNA damage. Cytogenetic and cytofluorimetric analyses were performed. We show that melatonin is able to modulate chromosome damage (chromosomal aberrations and sister chromatid exchanges) induced by cyclophosphamide. Conversely, its involvment in modulating oxidative processes, thereby reducing DNA damage, is less clear. In particular, melatonin is able to decrease H 2 O 2 -induced chromosomal aberrations but not sister chromatid exchanges and has been found to induce oxygen species in a cytofluorimetric test (DCFH assay).

To investigate the p53 ionizing radiation-induced response, G1/S cell-cycle block and cytogenetic damage in Nijmegen breakage syndrome (NBS) cells characterized by different haplotypes.Lymphoblastoid cell lines derived from three normals, five NBS and two ataxia telangiectasia (AT) individuals were treated with moderate doses of X-rays and changes in the p53 response were studied by dose-response and time-course experiments. Multiparametric flow cytometry analysis of bromodesoxyuridine-incorporated cells was carried out to analyse G1/S checkpoint alterations. Cytogenetic damage induced by 2 Gy radiation was assessed in cells harvested 28 h later.Comparison of mean values of p53 accumulation in NBS, AT and control cells indicated that protein induction in NBS cells was between normal and AT cells. Cell-cycle experiments showed a markedly reduced S-phase fraction in irradiated samples of normal cell lines, while NBS, and particularly AT cells, showed less reduction in S-phase fraction. Irrespective of differences in p53 induction and G1/S block, chromatid-type aberrations were induced at a comparable level in both syndromes, while being almost absent in normal cells.The data suggested that failure of NBS cells to initiate cell-cycle delay cannot account alone for their extreme sensitivity to radiation.

Ethionine is the ethyl analogue of the amino acid methionine. The agent is well known to have a weak demethylating activity. In addition, its capacity to reversibly block the cell cycle progression in G1 human lymphocytes (HL) without interfering with blastic transformation has been reported. In order to better understand the mechanism by which the agent is able to induce cell cycle block, experiments have been performed by using flow cytometry, in HL. In particular the hypothesis of the involvement of a specific target at the G0/G1 boundary was tested by treating HL at different times after blastic transformation. Starting from the 40th hour after PHA stimulation, ethionine loses its blocking capacity in such a way that cells challenged by the agent do not differ from controls in any one of the tested cell cycle-related parameters. We suggest the agent exerts its blocking activity at a specific stage of the transformation pathway.

The relationship between repair processes and chromosomal aberrations and X-ray-induced cell cycle perturbations were investigated in ataxia telangiectasia (AT) cells with 'intermediate' (AT-INT) and 'classical' radiosensitivity. In the cytogenetic experiments, three AT-INT lymphoblastoid cell lines were X-irradiated in G2-phase and incubated in the presence of inhibitors of DNA polymerases alpha/delta/epsilon (cytosine arabinoside, aphidicolin, 10% v/v DMSO), ribonucleotide reductase (hydroxyurea) and presumed inhibitors of protein kinases (caffeine). Flow cytometric analysis was performed in cells harvested 20 h after irradiation and stained with either propidium iodide or antibody against 5-bromodeoxiuridine in order to investigate cell cycle distribution focusing on G2/Mphase accumulation. From our data it appears that: (i) chromosomal sensitivity to radiation in AT does not always reflect clinical features; (ii) the effects of DNA repair inhibitors are inversely correlated with chromosomal radiosensitivity; and (iii) radiation-induced G2/M phase accumulation is a feature of AT cells and not necessarily correlated with cellular and chromosomal sensitivity to ionizing radiation.

To evaluate the possible genetic consequences of the industrial exposure among the vulcanizers of a rubber plant we measured the in vivo levels of chromosomal aberrations and sister-chromatid exchanges in peripheral lymphocytes of 34 vulcanizers and in an adequate control population. The observed chromosomal aberration frequencies were 1.9 ± 1.4 aberrations/100 cells in the exposed group and 2.1 ± 1.5 aberrations/100 cells in the controls. No difference was found between the two groups for the mean value of sister-chromatid exchanges (5.2 ± 1.3 in the exposed, 5.2 ± 0.7 in the control group). Cigarette-smoking was clearly associated with increased sister-chromatid exchange frequencies both in the exposed and in the control groups, while chromosomal aberration frequencies were not correlated with smoking habits.

Experiments were carried out to study the events through which the process of endoreduplication occurs after treatment with colchicine in Chinese hamster cells cultivated in vitro, and to analyse the differences between the processes leading to normal mitosis and those leading to endoreduplication. Chinese hamster cells (line C-125) were treated with colchicine (10 −4 M) for 1 h, in order to induce endoreduplication. Before and after colchicine treatment the cultures were treated at various intervals with actinomycin D and puromycin. For preparation of mitosis specific RNA synthesis is required, and also synthesis of a specific protein, which is not required for endoreduplication. Moreover this suggests not only that the cells that endoreduplicate do not need new RNA and protein synthesis, but that inhibition of their synthesis apparently favours the processes of endoreduplication.

The symmetry of radiation-induced chromatid exchanges was studied in relation to the cell cycle in Chinese hamster cells in vivo and in vitro. Both in vivo and in vitro, the ratio between symmetrical and asymmetrical chromatid exchanges was about 1 to 1 during G2 and S phase of the cell cycle.

To evaluate the possible genetic consequences of the industrial exposure among the vulcanizers of a rubber plant we measured the in vivo levels of chromosomal aberrations and sister-chromatid exchanges in peripheral lymphocytes of 34 vulcanizers and in an adequate control population. The observed chromosomal aberration frequencies were 1.9 +/- 1.4 aberrations/100 cells in the exposed group and 2.1 +/- 1.5 aberrations/100 cells in the controls. No difference was found between the two groups for the mean value of sister-chromatid exchanges (5.2 +/- 1.3 in the exposed, 5.2 +/- 0.7 in the control group). Cigarette-smoking was clearly associated with increased sister-chromatid exchange frequencies both in the exposed and in the control groups, while chromosomal aberration frequencies were not correlated with smoking habits.

Experiments conducted on the X irradiation of neural ganglia of Drosophila melanogaster are described. The ganglia were placed in saline containing colchicine. After two hours; they were irradiated and then samples were fixed at 5,15,25,35 minutes from the beginning of irradiation. The results obtained show that the aberration level increases with time subsequent to fixing. This increase takes place first for chromatid deletions and then for isochromatid deletions and chromatid exchanges. Gaps and subchromatid exchanges do not, on the contrary, show any increase with time. We did not observe a difference in radiosensitivity between the sexes. Some hypotheses are put forth in an attempt to explain these results.