Genotoxicity of hormoban and seven other pesticides to onion root tip meristematic cells

Plants are direct recipients of agro-toxics and therefore important materials for assessing environmental chemicals for genotoxicity. Three doses, representing ¼, ½ and EC50 of hormoban, storm killer, villa, fungi-nil, bexadust, aphicide, karbadust and basagran were assessed for cytotoxic and genotoxic effects to onion root tip cells in the root tip chromosome aberration assay after 24 h exposure. Cytotoxicity was inferred when the Mitotic index (dividing cells/1000 scored) of treated cellswas £ ½ negative control. All the pesticides were toxic. Genotoxicity was measured by analyzing 30 to 100 anaphase-telophase cells per dose of chemical for, chromosome fragments, bridges, vagrant chromosome, c-anaphase, multipolarity and stick chromosomes and comparing the percentage of aberrant cells at each dose with that of the negative control using the Chi-squared test. With the exception of basagran, the pesticides were genotoxic (P < 0.05). The C-anaphase and Stick chromosomes types of aberrations predominated which was evidence of the action of the pesticides on the mitotic spindle and the coiling of chromosomes during anaphase to telophase

Genotoxicity of Chlorpyrifos, Alpha-thrin, Efekto virikop and Springbok to onion root tip cells

The pesticides, chlorpyrifos, Alpha-thrin, Efekto virikop and springbok were assessed for cytotoxicity and genotoxicity in the onion root tip assay. Onion seeds were germinated on moistened filter paper inpetri dish at room temperature until radicles appeared. Germinated seeds were exposed to three concentrations of each pesticide for 20 h. About 1 – 2 mm length of root tip was cut, fixed in aceticalcohol, washed in ice cold water, hydrolyzed in warm 1 N HCl, stained with aceto-carmine and squashed on glass slide. For each treatment, about 3000 cells were scored and classified into interphase and normal or aberrant division stage. Cytotoxicity was determined by comparing the mitotic index (MI) of treated cells with that of the negative control. The MI of cells treated with chlorpyrifos, Alpha-thrin or springbok was half or less, that of the control at one or more doses andadjudged cytotoxic. Efekto virikop was not cytotoxic. Genotoxicity was measured by comparing the number of cells/1000 in aberrant division stages at each dose with the negative control using the Mann-Whitney test. Chlorpyrifos was genotoxic (P < 0.05), inducing chromosome lagging and bridges, pulverized and stick chromosomes, multipolar anaphase and telophase. Efekto virikop and springbokinduced lagging chromosomes. Alpha-thrin was not genotoxic

Lack of modulatory effect of asparagus, tomato, and grape juice on cyclophosphamide-induced genotoxicity in mice

Studies on agents that modulate carcinogen-induced genotoxic effects in experimental animals are used to assess the antimutagenic or anticarcinogenic properties of putative chemopreventivecompounds. We investigated the potency of asparagus-, tomato- and red grape-juice to modify the proportion of polychromatic erythrocyte (PCE) and frequency of micronucleated polychromatic erythrocytes (MNPCE) induced by cyclophosphamide (CP) in male NIH mice. Groups of five mice were given the fruit juices (25, 50 or 100%) respectively, ad libitum, for 44 days then intraperitoneally (ip) injected with 40 mg/kg CP and killed 24 h later for cytological preparations and analysis. The control group animals were injected with CP (positive) or purified water (negative). Each group mean of the proportion of PCE and frequency of MNPCE was compared with the negative and positive control usingthe Mann-Whitney test. No statistically significant difference was found between the proportion of PCE in any experimental group and the negative control (

Simultaneous Determination of Mutagenicity and Toxicity of Chemicals to Chinese Hamster Cells Using Delayed Toxicity Method

Induction of chromosome damage in mammalian cells by chemicals generally requires DNA replication and this leads to delayed toxic effect, i.e. cell death. A demonstration of cytotoxicity is required (measurement of cell number, culture confluency and inhibition of mitotic index) for in vitro cytogenetic assays. The study therefore investigated whether delayed cytotoxicity can be used to simultaneously predict mutagenicity and cytotoxicty. Chinese hamster lung cells were cultured in 96-well microtitre plates, incubated until they were actively dividing, then exposed for 3 hours to Methylmethane sulfonate (MMS), Cyclophosphamide (CPH), Dimethyl sulfoxide (DMSO) or 3-Methylcholanthrene (3-MC). Cytotoxicity was assessed indirectly at intervals from 0 to 72 hours after exposure, using MTT uptake and reduction, with optical density values from the purple formazan product being expressed relative to the concurrent solvent control. The results showed experimental variability from one time point to the next, which may mask subtle changes such as cell cycle delay. Toxicity profile for tests with MMS or CPA changed as time passed. Toxicity profile for DMSO tests remained similar throughout, while that for the relatively non-toxic 3-MC treated cells was not definitive because any effects were too subtle for the test system to detect. This approach appears to be suitable for detection of substances that damage chromosomes and are evidently toxic. Key Words: Chromosome damage, delayed toxicity, screen for genotoxins Résumé L'induction des lesons chromosomale chez les mamiferes par les substance chimique generalement necesite la replication de l'AND et ceci genere un effet toxique retarde i.e la mort de la cellule .la mesure de la cytotoxicite est requise.( la mesure du nombre de cellule, la confluence de la culture et l'inhibation de l'index mitotique)de l'assy cytogenique invitro. L'etude a ainsi invitigue si la cytotoxicite retarde peu etre simultanement utilize pour predire la mutagenicite et la cytotoxicite. Les cellule pulmonaire du Chinese hamster onete cultive dans 96 plaquettes bien microtitre. incube jusqu'au point ou elle se divise activement,ensuite expose pendant 3 heures au sulfonate de methylmethane (SMM), cyclophosphamide (CPH), dimethyl sulfoxide(DMSO)ou3-methylcholanthre(3-MC). La cytotoxicite a ete mesure indirectement a des intervals de 0 a 72heurs après exposition utilisant l'absorption et la reduction du MTT,avec la densite optique des valeurs du produitfromazan marron etant relativement exprime au olvent de controlles resutats ont demontre experimentalement la variabilite d'un temps de point a l'autre, qui peut masque des changement subtile telque le retardement du cycle cellulaire. Le profile de test toxicite avec SMM ou CPA au fur et a mesure que le temps passé.le profile de test de toxicite pour le DMSO restait similair tout au long alors celui des cellule traite au 3-MC relativement non toxiquen'etait pas definitive parceque les effet etaient trop subtile pour etre detecte par ce systeme de test. Cette approchhe aparait tres approprie pour detecte les substances qui endomage les chromosome et ils sont evidement tocique. Mot cles : Lesion chromosomique, toxicite retarde, depistage de genotoxine West Afr. J. Pharmacol. Drug Res. Vol.19 (1&2) 2003: 5-

Investigation to Determine Whether Delayed Toxicity Can be used to Predict Genotoxicity in vitro

Induction of chromosome damage in mammalian cells by chemicals generally requires DNA replication and toxicity is, therefore, delayed. We, therefore, investigated whether delayed cytotoxicity can be used to predict genotoxicity. Dividing Chinese Hamster Lung (CHL) cells cultured in 96 well microtitre plates, were exposed for 3 hours to Mitomycin C (MMC), Cyclophosphamide (CPH), Methylmethane sulfonate (MMS), 2-Nitrofluorene (2-NF), Dimethyl sulfoxide (DMSO), Sodium dodecyl sulfate (SDS), 9-Aminoacridine (9-AA) or 3-Methylcholanthrene (3-MC). Cytotoxicity was assessed indirectly at intervals from 0 to 72 hours after the end of exposure, using MTT uptake and reduction. The toxicity profiles of cells treated with the known genotoxins, MMC, CPA, MMS, or 9-AA, changed as time passed, while the toxicity profiles of cells treated with the nongenotoxins, DMSO or SDS remained similar throughout. However, 2-NF and 3-MC were relatively non-toxic and any effects were too subtle for the test system to detect. These results are preliminary yet this approach appears to be suitable for detection of substances that damage chromosomes (mutagens) and are evidently toxic. Keywords: Chromosome damage, delayed cytotoxicity, screen for genotoxinsDiscovery and Innovation Vol. 19 (4) 2007: pp. 285-29