Root Meristems Of Allium Cepa Research Articles

Clastogenic and Cytotoxic Effects of Four Pesticides Used to Control Insect Pests of Stored Products on Root Meristems of Allium cepa

While the use of pesticides of stored product has increased productivity in agriculture, there is concern about their use because some are mutagens and/or carcinogens, harm non-target organisms or cause pest resistance. In this study Grain Treat (GT) (Mercaptothion, 10 g kg -1 , Permethrin 1.5 g kg -1 ); QuickPhos (QP) (Aluminium Phosphide, 560 g kg -1 ); Nuvan Profi (NP) (Dichlorvos, 124 g kg -1 ) and Eriocephalus punctulatus plant smoke condensate (EPSC) were evaluated for cytotoxicity and the induction of genotoxicity in the onion (Allium cepa) test. Onion seeds were germinated and exposed to pesticides (mg ml -1 ), GT (12.5, 25, 50); QP (0.75, 1.5, 3.0); NP (0.064, 0.128, 0.256); EPSC (0.0025, 0.0049, 0.0098) for 24 hours. For each concentration, three root tips were transferred to three microscope slides, stained with aceto-carmine, covered with cover slip, squashed and observed microscopically. The cytotoxicity and genotoxicity induced by each pesticide concentration was compared with the value for the concomitant negative control using t-test. Only QP (3.0 mg mL -1 ) and NP (0.256 mg mL -1 ) significantly depressed the MI, i.e. cytotoxic (P multipolarity > c-mitosis > anaphase and telophase bridges > chromosome Largards. The induction of sticky chromosomes indicated that the pesticides caused abnormal DNA condensation, abnormal chromosome coiling and inactivated the spindles. Because abnormalities of the cell division process results from the genotoxic effects of environmental chemicals, the four pesticides have the potential to cause aneuploidy in exposed organisms and adverse human health and environmental effects.

Radioprotective and cytoprotective activity of Tinospora cordifolia stem enriched extract containing cordifolioside-A

Objectives:The present study was undertaken to evaluate the radioprotective and cytoprotective potential of cordifolioside-A, a primary active constituent of n-butanol fraction of Tinospora Cordifolia (NBTC) against 4 Gy-γ radiation in mice and cyclophosphamide induced genotoxicity.Materials and Methods:Presence of cordifolioside-A in NBTC stem ethanolic extract was confirmed by high performance thin layer chromatography (HPTLC) analysis. Radioprotective activity was evaluated at 80 and 120 mg/kg, intraperitoneal (i.p.) dose of NBTC administered 15 days prior to whole body radiation exposure by observing survival rate, change in body weight, hematology, spleen colony forming unit (CFU), and micronucleus (MN) expression. Cytoprotective activity of NBTC was evaluated at 5, 10, and 15 mg/ml concentrations on Allium cepa root meristem growth against cyclophosphamide.Results:HPTLC analysis of standard cordifolioside A, and NBTC confirmed the presence of cordifolioside-A in NBTC with the retention factor value of 0.86. Administration of NBTC (120 mg/kg, i.p.) produced significant protection against radiation in terms of increased survival rate, body weight retention, hematological parameters, spleen CFU assay (P < 0.01), and decreased MN expression (P < 0.01). Cytoprotectivity was observed maximally at 10 mg/ml NBTC concentration with significant increase in root growth (P < 0.01), non-toxic mitotic index (MI) (65.9%) and lesser chromosomal aberrations (15.4%). NBTC at 10 mg/ml concentration showed very few C-anaphase compared to aberrations like fragmentation, C-anaphase, multipolarity and sticky chromosome in cyclophosphamide alone.Conclusion:The results suggest that enriched NBTC containing cordifolioside-A has a potential in vivo radioprotective effect as well as in vitro cytoprotective activity.

DNA replication stress induces deregulation of the cell cycle events in root meristems of Allium cepa

Prolonged treatment of Allium cepa root meristems with changing concentrations of hydroxyurea (HU) results in either premature chromosome condensation or cell nuclei with an uncommon form of biphasic chromatin organization. The aim of the current study was to assess conditions that compromise cell cycle checkpoints and convert DNA replication stress into an abnormal course of mitosis. Interphase-mitotic (IM) cells showing gradual changes of chromatin condensation were obtained following continuous 72 h treatment of seedlings with 0·75 mm HU (without renewal of the medium). HU-treated root meristems were analysed using histochemical stainings (DNA-DAPI/Feulgen; starch-iodide and DAB staining for H(2)O(2) production), Western blotting [cyclin B-like (CBL) proteins] and immunochemistry (BrdU incorporation, detection of γ-H2AX and H3S10 phosphorylation). Continuous treatment of onion seedlings with a low concentration of HU results in shorter root meristems, enhanced production of H(2)O(2), γ-phosphorylation of H2AX histones and accumulation of CBL proteins. HU-induced replication stress gives rise to axially elongated cells with half interphase/half mitotic structures (IM-cells) having both decondensed and condensed domains of chromatin. Long-term HU treatment results in cell nuclei resuming S phase with gradients of BrdU labelling. This suggests a polarized distribution of factors needed to re-initiate stalled replication forks. Furthermore, prolonged HU treatment extends both the relative time span and the spatial scale of H3S10 phosphorylation known in plants. The minimum cell length and a threshold level of accumulated CBL proteins are both determining factors by which the nucleus attains commitment to induce an asynchronous course of chromosome condensation. Replication stress-induced alterations in an orderly route of the cell cycle events probably reflect a considerable reprogramming of metabolic functions of chromatin combined with gradients of morphological changes spread along the nucleus.

Image cytometric determination of nuclear and chromosomal DNA contents in Allium cepa L.

Estimation of DNA content in individual chro- mosomes and their arms was carried out in the primary root meristems of Allium cepa L. var Local, (2n=16) using an Image Analysis System following Feulgen staining. Re- gression analysis revealed that fifth and seventh chromo- somes had higher DNA contents relative to their chromosomal lengths while the 1st, 2nd and 4th chromo- somes had less DNA contents than those expected on the basis of length.

Hydrogel containing dexamethasone-loaded nanocapsules for cutaneous administration: preparation, characterization, and in vitro drug release study

Context: Our group previously reported the development of dexamethasone-loaded polymeric nanocapsules as an alternative for topical dermatological treatments. Objective: Our study aimed to prepare and characterize a hydrogel containing this system to improve the effectiveness of the glucocorticoid for cutaneous disorders. Methods: For the antiproliferative activity assay, a dexamethasone solution and D-NC were tested on Allium cepa root meristem model. D-NC were prepared by the interfacial deposition of preformed polymer. Hydrogels were prepared using Carbopol Ultrez® 10 NF, as polymer, and characterized according to the following characteristics: pH, drug content, spreadability, viscosity, and in vitro drug release. Results and Discussion: Nanocapsules showed mean particle size and zeta potential of 201 ± 6 and −5.73 ± 0.42 nm, respectively. They demonstrated a lower mitotic index (4.62%) compared to free dexamethasone (8.60%). Semisolid formulations presented acidic pH values and adequate drug content (between 5.4% and 6.1% and 100% and 105%, respectively). The presence of nanocapsules in hydrogels led to a decrease in their spreadability factor. Intact nanoparticles were demonstrated by TEM as well as by dynamic light scattering (mean particle size < 300 nm). In vitro studies showed a controlled dexamethasone release from hydrogels containing the drug associated to the nanocapsules following the Higuchi's squared root model (k = 20.21 ± 2.96 mg/cm2/h1/2) compared to the hydrogels containing the free drug (k = 26.65 ± 2.09 mg/cm2/h1/2). Conclusion: Taking all these results together, the hydrogel containing D-NC represent a promising approach to treat antiproliferative-related dermatological disorders.

Inter- and intrachromosomal asynchrony of cell division cycle events in root meristem cells of Allium cepa: possible connection with gradient of cyclin B-like proteins

Alternate treatments of Allium cepa root meristems with hydroxyurea (HU) and caffeine give rise to extremely large and highly elongated cells with atypical images of mitotic divisions, including internuclear asynchrony and an unknown type of interchromosomal asynchrony observed during metaphase-to-anaphase transition. Another type of asynchrony that cannot depend solely on the increased length of cells was observed following long-term incubation of roots with HU. This kind of treatment revealed both cell nuclei entering premature mitosis and, for the first time, an uncommon form of mitotic abnormality manifested in a gradual condensation of chromatin (spanning from interphase to prometaphase). Immunocytochemical study of polykaryotic cells using anti-β tubulin antibodies revealed severe perturbations in the microtubular organization of preprophase bands. Quantitative immunofluorescence measurements of the control cells indicate that the level of cyclin B-like proteins reaches the maximum at the G2 to metaphase transition and then becomes reduced during later stages of mitosis. After long-term incubation with low doses of HU, the amount of cyclin B-like proteins considerably increases, and a significant number of elongated cells show gradients of these proteins spread along successive regions of the perinuclear cytoplasm. It is suggested that there may be a direct link between the effects of HU-mediated deceleration of S- and G2-phases and an enhanced concentration of cyclin B-like proteins. In consequence, the activation of cyclin B-CDK complexes gives rise to an abnormal pattern of premature mitotic chromosome condensation with biphasic nuclear structures having one part of chromatin decondensed, and the other part condensed.

Evaluation of in vitro cytotoxic effect of Trichosanthes dioica root

Background:Trichosanthes dioica Roxb. (Cucurbitaceae), called pointed gourd in English is a dioecious climber grown in India and used traditionally for various medicinal purposes.Methods:Present study was aimed to evaluate in vitro cytotoxic effect of dichloromethane (DCTD), methanol (METD), and aqueous (AQTD) extracts of T. dioica root using Allium cepa root meristems by keeping them in different concentrations of each test extract under specific experimental conditions followed by determination of root growth inhibition (root length and number) and mitotic index.Results:All the extracts significantly demonstrated concentration-dependent inhibition of root length and number and reduction in mitotic index, indicating antimitotic activity demonstrating cytotoxicity and genotoxicity. DCTD was found to be the most potent (EC50 : 2.8 mg/ml), followed by METD and AQTD.Conclusion:The present study therefore, establishes promising in vitro cytotoxic and genotoxic property of T. dioica root against the test system.

General Toxicity and Genotoxicity of Nodularia Moravica (Cyanoprokaryota, Nostocales)

ABSTRACTGeneral toxicity and genotoxicity of cyanoprokaryote Nodularia moravica was investigated on the base of Allium root meristem in vivo test system. Seeds sprouted in dechlorinated tap water were analyzed as a control sample. Seeds sprouted in the water-Dimethyl sulfoxide (9:1, v:v) extract, diluted 50 and 100 times (D1–797 and D2-797, respectively) were used as test samples. It was found that different concentrations of dilutions of the initial extract of cyanoprokaryote Nodularia moravica induced damages such as micronuclei (MNi), fragments, anaphasic and telophasic bridges and laggards with higher total frequency than in the control. Germination percentage and root length were found to be in positive correlation with percentage of chromosome aberrations and depend on the extract concentration. It was concluded that Nodularia moravica extract in water-DMSO solution induces general and genotoxycity in Allium cepa root meristem cells. There were not found data about cytotoxicity.

Cytogenetic damage in Allium cepa root meristems induced by Dursban 4 and Antracol WP 7 pesticides

Cytogenetic damage in Allium cepa root meristems induced by Dursban 4 and Antracol WP 7 pesticides

Epoxytrichothecene mycotoxins as c-mitotic agents in Allium

The cytogenetic effects of purified mycotoxins produced by toxicogenic strains of two species of grain fungi were studied in the growing root meristem of Allium cepa. Both toxins, the T-2 toxin of Fusarium tricinctum and Satratoxin H of Stachybotrys alternans are strong mitotic inhibitors in concentrations higher than 10 ppm (w/v). Their potential to arrest metaphases and to induce c-mitotic chromosome morphology is comparable to the action of colchicine.

Mutagenic Potentials of the Sterilizing Fluid – Puritil on Root Tip Mitosis of &lt;i&gt;Allium cepa&lt;/i&gt;

The mutagenic potentials of puritil which is used for sterilizing babies feeding utensils were assessed using the Allium cepa root meristem assay. The sterilizing fluid was found to exhibit both mitoclassic and chromatoclassic effects and thus induced a number of abnormalities. These abnormalities included disturbed interphase involving nuclear lesions and nuclear dissolutions, micronuclei and binucleate cells, sticky metaphase, disturbed anaphase involving unequal distribution of chromosomes and sticky bridges, and precocious chromosomes. These increased with increase in concentration and duration of treatment. Thus the mutagenic potentials of puritil exist and it should be of great concern since babies are exposed to it for at least the first two years of life. Keywords: Mutagenic, Potentials, Puritil, Root Tips, Allium cepaBio-Research Vol. 6 (1) 2008: pp. 293-297

Effects of polyamines and polyamine biosynthetic inhibitors on mitotic activity ofAllium ceparoot tips

The genotoxic and cytotoxic effects of exogenous polyamines (PAs), putrescine (Put), spermidine (Spd), spermine (Spm) and PA biosynthetic inhibitors, alpha-difluoromethylornithine (DFMO), cyclohexilamine (CHA), methylglioxal bis-(guanylhydrazone) (MGBG) were investigated in the root meristems of Allium cepa L. The reduction of mitotic index and the induction of chromosomal aberrations such as bridges, stickiness, c-mitotic anaphases, micronuclei, endoredupliction by PAs and PA biosynthetic inhibitors were observed and these were used as evidence of genotoxicity and cytotoxicity.

Antimutagenic potential of curcumin on chromosomal aberrations in Allium cepa

Turmeric has long been used as a spice and food colouring agent in Asia. In the present investigation, the antimutagenic potential of curcumin was evaluated in Allium cepa root meristem cells. So far there is no report on the biological properties of curcumin in plant test systems. The root tip cells were treated with sodium azide at 200 and 300 microg/ml for 3 h and curcumin was given at 5, 10 and 20 microg/ml for 16 h, prior to sodium azide treatment. The tips were squashed after colchicine treatment and the cells were analyzed for chromosome aberration and mitotic index. Curcumin induces chromosomal aberration in Allium cepa root tip cells in an insignificant manner, when compared with untreated control. Sodium azide alone induces chromosomal aberrations significantly with increasing concentrations. The total number of aberrations was significantly reduced in root tip cells pretreated with curcumin. The study reveals that curcumin has antimutagenic potential against sodium azide induced chromosomal aberrations in Allium cepa root meristem cells. In addition, it showed mild cytotoxicity by reducing the percentage of mitotic index in all curcumin treated groups, but the mechanism of action remains unknown. The antimutagenic potential of curcumin is effective at 5 microg/ml in Allium cepa root meristem cells.

Cytogenetic damage in shallot ( Allium cepa) root meristems induced by oil industry "high-density brines".

Saturated water solutions of calcium chloride, calcium bromide (densities 1.30 kg x dm(-3) and 1.61 kg x dm(-3), respectively) and their 1:1 mixture have been commonly used as oil industry "high-density brines." In our experiment they were added to tap water in amounts appropriate to achieve concentrations of 0.025, 0.05, 0.075, and 0.1 mol x dm(-3) to study their cytotoxic effect on the root tip cells of shallot ( Allium cepa L. var. ascalonicum). All tested solutions in concentrations of 0.075 and 0.1 mol x dm(-3) caused significant inhibition of shallot root growth. CaBr (2) showed this effect in concentration 0.05 mol x dm(-3). The investigated solutions in all concentrations applied decreased mitotic activity in root tip cells. The most of mitotic abnormalities were the consequence of spindle failure and chromosome stickiness. Furthermore, the cell microtubules were investigated by indirect immunofluorescence to confirm that most abnormalities observed were the consequence of spindle failure. The present study, as well as previously done Lemna tests and Chlorella tests showed that investigated samples have certain effects on plants, so constant control of their presence in the environment is needed.

Evaluation of the genotoxic potential of municipal waste water discharged into the Paraguay River during periods of flood and drought.

The cytogenotoxic effects of the waste water from Corumbá and of the water of the Paraguay River, where this sewer discharges, were evaluated in flood and drought seasons. Allium cepa root meristems were exposed to 20 and 72 h treatments. Mitotic index, frequency, and types of aberrant cells were compared to the control. The waste water was genotoxic to this organism. The cycle of flood and drought influenced the levels of genotoxicity observed with the river water.

The Action of Atrazine Herbicide as an Inhibitor of Cell Division on Chromosomes and Nucleic Acids Content in Root Meristems of Allium cepa and Vicia faba.

The present investigation was carried out to study the cytological effects of the herbicide atrazine on Allium cepa and Vicia faba with respect to the cell cycle response, mitotic index, chromosome aberrations and nucleic acids content. The root of young seedlings of V. faba and adventitious roots of A. cepa were treated with the following concentrations : 25%, 50%, 75% and 100% of the recommended dose (3.75 g/l) for 4, 8, 12, 24 h. The results indicated that atrazine herbicide reduced the mitotic division in both plants compared to the respective control. Mitotic index values were progressively decreased with increased the concentration and treatment time. In V. faba, the treatment with the concentration of 100% for each treatment time (4, 8, 12, 24 h) was toxic, but in A. cepa, the same concentration with 24 h was only toxic. The percentage of the reduction in MI values in V. faba was higher than that in A. cepa. Also, it has been clearly observed that the inhibition of mitotic division was associated with reduction in DNA and RNA contents in both treated plants root tips. This may point out that the inhibition of mitotic activity is due to a deficiency of DNA in the nucleus. The increased percentage of prophase in both plants was accompanied by decreased percentages of the other mitotic phase. The total percentage of aberrations increased with the increasing the concentration of atrazine herbicide and the period of treatment. The total percentage of aberrations in A. cepa was higher than that in V. faba for each treatment. Different abnormal mitotic figures were observed in all mitotic phases. Such types of abnormalities were stickiness, lagging, C-mitosis, bridges, irregular prophase, unequal distribution, fragments and a few cells with micronucleus at interphase stage.

The effect of lead on the cell cycle in the root meristem ofAllium cepa L.

Allium cepa (L.) adventitious roots were treated with lead (2.5 mg of Pb2+ [from Pb(NO3)2] per dm3) for 30–72 h. The cell cycle was studied by pulse labeling with [3H]thymidine. Mitotic activity kinetics, occurrence of disturbed mitoses (c-mitoses), and level of DNA synthesis were examined. It was found that lead prolonged the cell cycle and that cells in two phases of the cycle, G2 and S, differed in their sensitivity to lead. Cells in G2 were more sensitive; lead lengthened their cycle by 216% and disturbed the course of cell division by causing c-mitoses. Cells in S phase were less sensitive. Their cell cycle was longer by 55%. They went through their G2 phase without major disturbances, mitosis in these cells was normal. During treatment ofA. cepa with lead, its destructive effects on cells were exerted only during the first few hours (around 6 h) of incubation. That is when the inhibition of mitotic activity, numerous disturbances of cell division, a decline in the number of cells synthesizing DNA, and a lower level of DNA synthesis were observed. As the incubation continued, the above processes were found to return to normal. In the discussion, data are presented supporting the hypothesis that during the initial period of exposure ofA. cepa to lead, this metal enters both the root apoplast and symplast, exerting a destructive effect on cells, while later, lead penetrates only into the root apoplast, and in this way remains harmless to cells.

Persistence of cadmium-induced adaptive response to genotixicity of maleic hydrazide and methyl mercuric chloride in root meristem cells of Allium cepa L.: Differential inhibition by cycloheximide and buthionine sulfoximine

With an objective to determine the period of persistence of the metal-induced adaptive response to chemical mutagens and heavy metals, growing root meristems of Allium cepa were conditioned by cadmium sulfate (CdSO 4), 4×10 −7 and 4×10 −6 M for 1 h and subsequently challenged by maleic hydrazide (MH), 5×10 −3 M or methyl mercuric chloride (MMCl), 1.26×10 −6 M for 3 h at different time intervals ranging from a few minutes to several hours following the conditioning dose. Root meristems, fixed at regular intervals during recovery from 6 to 48 h, were cytologically analysed for cells with micronuclei (MNC). The adaptive responses to MH and MMCl were observed as early as 5 min after the Cd-conditioning that persisted for at least 48 h. Metabolic inhibitors, cycloheximide (CH), 10 −7 M and buthionine sulfoximine (BSO), 10 −4 M administered either prior to or simultaneous with Cd-conditioning effectively prevented the adaptive response to MH. Whereas BSO, an inhibitor of phytochelatin synthesis, prevented the adaptive responses from 15 min to 8 h after the conditioning dose, CH an inhibitor of cytoplasmic protein synthesis prevented the same from 6 to 48 h. The findings underscored the differential roles of phytochelatins and proteins underlying the foregone metallo-adaptive response.

Studies on Cytological Changes Induced by Muriate of Potash in Allium cepa.

The cytological abnormalities produced by muriate of potash were evaluated using Allium cepa root meristem assay. Studies using different concentrations of the fertilizer showed that concentrations ranging from 200 ppm to 2000 ppm produced significant increase in chromosomal aberrations and other abnormalities over the control. This study indicates that the fertilizer is capable of upsetting normal cell divisions if excessive amounts are present in the soil.

The improved Allium/Vicia root tip micronucleus assay for clastogenicity of environmental pollutants

The meristematic mitotic cells of plant roots are appropriate and efficient cytogenetic materials for the detection of clastogenicity of environmental pollutants, especially for in situ monitoring of water contaminants. Among several cytological endpoints in these fast dividing cells, such as chromosome/chromatid aberrations, sister-chromatid exchanges and micronuclei, the most effective and simplest indicator of cytological damage is micronucleus formation. Although the Allium cepa and Vicia faba root meristem micronucleus assays (Allium/Vicia root MCN) have been used in clastogenicity studies about 12 times by various authors in the last 25 years, there is no report on the comparison of the efficiency of these two plant systems and in different cell populations (meristem and F 1) of the root tip as well as under adequate recovery duration. In order to maximize the efficiency of these bioassays, the current study was designed to compare the Allium and the Vicia root MCN assays on the basis if chromosome length, peak sensitivity of the mitotic cells, and the regions of the root tip where the MCN are formed. The total length of the 2n complement of Allium chromosomes is 14.4 μm and the total length of the 2n complement of Vicia is 9.32 μm. The peak sensitivity determined by serial fixation at 12-h intervals after 100 R of X-irradiation is 44 h. The slope of the X-ray dose-response curve of Allium roots derived from the meristematic regions was lower than that derived from cells in the F 1 region. Higher efficiency was also demonstrated when the MCN frequencies were scored from the F 1 cells in both Allium and Vicia treated with formaldehyde (FA), mitonycin C (MMC), and maleic hydrazide (MH). The results indicated that scoring of MCN frequencies from the F 1 cell region of the root tip was more efficient than scoring from the meristematic region. The X-ray linear regression dose-response curves were established in both Allium and Vicia cell systems and the coefficients of correlations, slope values were used to verify the reliability and efficiency of these two plant cell systems. Based on the dose-response slope value of 0.894 for Allium and 0.643 for Vicia, the Allium root MCN was a more efficient test system. The greater sensitivity of the Allium roots is probably due to the greater total length of the diploid complement and the higher number of metacentric chromosomes. The Allium/Vicia root MCN test system was applied to determine the clastogenicity of saccharin (SC) and wastewater from Rio Queretaro and the Arena canal in the city of Queretaro, Mexico. The minimum effective dose (MED) is 10 R for X-rays, 50 mM for FA, 2.2 mM for MMC, 0.01 mM for MH, and 40 ppm for SC.