Efficient micropropagation of Thunbergia coccinea Wall. and genetic homogeneity assessment through RAPD and ISSR markers.

Thunbergia coccinea Wall. ex D. Don being a rare, ornamental and medicinal plant of India, is needed to propagate for conserving the germplasm and analyzing its phytochemical compounds in the future. A reliable protocol for direct in vitro propagation using nodal shoot meristem of T. coccinea as explant was standardized. The highest number of shoots per explant (22.17 ± 0.54) with maximum shoot length (2.36 ± 0.28) in cm was obtained in Murashige and Skoog (MS) medium supplemented with 9.70 µM of 6-furfurylaminopurine (Kinetin) and 0.053 µM of α-naphthaleneacetic acid (NAA) combination, among all the different plant growth regulators (PGR's) and concentrations tested. The aforesaid PGR's combination was optimum for axillary shoot bud induction and multiplication in T. coccinea. The best rooting was observed on the half-strength MS medium fortified with 2.68 µM NAA with the highest number of roots per shoot (3.75 ± 0.12) and maximum length (5.22 ± 0.32) in cm. All the in vitro raised plantlets were acclimatized in sterile sand and soil mixture (1:1) with a survival rate of 70% on earthen pots under greenhouse conditions. PCR-based RAPD (Random Amplified Polymorphic DNA) and ISSR (Inter-Simple Sequence Repeat) molecular markers were employed to determine the genetic homogeneity amongst the plantlets. Twelve (12) RAPD and nine (9) ISSR primers developed a total of 104 and 91 scorable bands, respectively. The band profiles of micropropagated plantlets were monomorphic to the mother, donor in vivo plant, and similarity values varied from 0.9542-1.000. The dendrogram generated through UPGMA (unweighted pair group method with arithmetic mean) showed 99% similarities amongst all tested plants confirming the genetic uniformity of in vitro raised plants.

Toxicity assessment of zinc sulfate: A commonly used compound.

Because zinc sulfate (ZnSO4) is widely used in many fields such as biomedicine, electronics, and chemistry, it is important to evaluate its toxic effects. In this study, the cyto-genotoxic effects of ZnSO4 on meristematic cells in the root tip of Allium cepa L. were investigated. After calculating the effective concentration (EC50 = 70 ppm) of ZnSO4, A. cepa root tip cells were suspended for 24, 48, 72, and 96 h in solutions of 35 ppm (EC50/2), 70 ppm (EC50), and 140 ppm (EC50 × 2) concentrations. Using the counts of dividing cells, the mitotic index (MI) was calculated. Chromosome aberration index (CAI) was determined from percentages of abnormal cells. When the obtained data were statistically evaluated, it was determined that all application concentrations caused a significant decrease in MI and an increase in CAI compared to the control group (distilled water). It was concluded that increased ZnSO4 dose concentrations and exposure times caused cytotoxicity and genotoxicity in the root cells of A. cepa L.

Cytogenetic and genotoxic assessment in Allium cepa exposed to imazalil fungicide.

Imazalil (IMZ), a fungicide containing imidazole group, is extensively used for the prevention and treatment of fungal diseases in plants. Current study was performed to examine cyto-genotoxic potential of IMZ on Allium cepa roots by following Allium ana-telophase and single cell gel electrophoresis (comet) assays. The concentration which reduced the growth of the root tips of IMZ by 50% compared to the negative control group (EC50) was found to be 1 µg/mL by Allium root growth inhibition test. 0.5, 1, and 2 µg/mL concentrations of IMZ were exposed to Allium roots for intervals of 24, 48, 72, and 96 h. 10 µg/mL of methyl methane sulfonate (MMS) and distilled water were used as control groups, both positive and negative. Statistical analysis was performed by using one-way ANOVA with Duncan's multiple comparison tests at p ≤ 0.05 and Pearson correlation test at p = 0.01. IMZ showed cytotoxic effect by statistically decreasing root growth and mitotic index (MI) and also genotoxic effect by statistically increasing chromosomal aberrations (CAs) and DNA damage compared to the negative control group. With these cyto-genotoxic effects, it should be used carefully and further cyto-genotoxic mechanisms should be investigated along with other toxicity tests.

Cytotoxic and Genotoxic Assessment of Silicon Dioxide Nanoparticles by Allium and Comet Tests.

Silicon nanoparticles gained a great interest due to its use in biomedical research. It is considered as safe and has been used in nanomedicine. But literature still states its toxicity depending upon the size and dose of silicon nanoparticles. So, current study was aimed to evaluate the cytotoxicity and genotoxicity of silicon dioxide nanoparticles (SiO2NPs) by Allium anaphase-telophase and Comet tests. Characterization of SiO2NPs showed the particle size as 16.12 ± 3.07 nm. The mean diameter of SiO2NPs was having range of 404.66 ± 93.39 nm in solution. Highest total anomalies (18.80 ± 0.45) were observed at 100 µg/mL, whereas least (11.2 ± 0.84) were observed by the 12.5 µg/mL concentration. There was concentration-response association in increased CAs and DNA damage. The highest concentration (100 µg/mL) of SiO2NPs induced the significant DNA damage (149.67 ± 1.15), whereas the least was observed by the negative control (2.67 ± 0.58). The current study revealed the cytotoxic and genotoxic effects of SiO2NPs on the root meristem cells of A. cepa.

Comparative ecotoxicity assessment of magnetosomes and magnetite nanoparticles.

Magnetite nanoparticles (MNPs) are gaining attention because of their biomedical, environmental and industrial applications. However, they have limited uses because of ecotoxicity. On contrast, bacterially synthesized MNPs such as magnetosomes are found to be biocompatible and less toxic due to the lipid bilayer membrane found around magnetite. In this context, this study compares the physio-chemical properties and toxicology effects of MNPs and magnetosomes in different models such as human red blood cells, macrophage cell lines (RAW 264.7), onion root tips (Allium cepa), Artemia salina (A. salina) and zebrafish embryo (Danio rerio). MNPs showed 38.59% hemolysis whereas the maximum hemolysis induced by magnetosomes was 7.03% for the same concentration (250 µg/ml). The cytotoxicity of MNPs and magnetosomes were 36.01% and 13.4%, respectively, at 250 µg/ml. Onion root tip assay revealed high toxicity when treated with MNPs than magnetosomes. The MNPs were further tested for its toxicity against A. salina and 50% mortality rate was observed. Similarly, notable malformation was seen in zebrafish embryo treated with MNPs. However, magnetosomes did not exhibit any mortality and malformation in A. salina and zebrafish embryo. The study revealed that magnetosomes are safe and do not cause any potential risk to environment compared to synthetic MNPs.Abbreviation: MNPs: Magnetic nanoparticles; ATCC: American Type Culture Collection; MTB: Magnetotactic bacteria; MSR-1: Magnetospirillum gryphiswaldense; DSMZ: Deutsche Sammlung von Mikroorganismen und Zellkulturen; MSGM: Magnetospirillum growth medium; D-PBS: Dulbecco phosphate buffer saline; RBC: Red blood cells; SEM: Scanning electron microscopy; HRTEM: High-resolution transition electron microscope; FTIR: Fourier transform infrared spectroscopy; XRD: X-ray powder diffraction; AFM: Atomic-force microscopy; ZP: Zeta Potential; PSD: Particle Size Distribution; EDX: Energy-dispersive X-ray spectroscopy; PBS: Phosphate buffer saline; DMEM: Dulbecco's modified eagle medium; HEPES: (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid); MTT:3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide; DMSO: Dimethyl sulfoxide; ROS: Reactive oxygen species.

Assessment on interactive prospectives of nanoplastics with plasma proteins and the toxicological impacts of virgin, coronated and environmentally released-nanoplastics.

Recently, the concerns about micro- and nano-plastics (NPs) toxicity have been increasing constantly, however the investigations are quiet meager. The present study provides evidences on the toxicological prospectives of virgin-, coronated- and isolated-NPs on human blood cells and Allium cepa root tip, respectively. Several plasma proteins displayed strong affinity towards NPs and produced multi-layered corona of 13 nm to 600 nm size. The coronated-NPs often attracted each other via non-specific protein-protein attraction which subsequently induced protein-induced coalescence in NPs. In the protein point of view, the interaction caused conformational changes and denaturation of protein thereby turned it as bio-incompatible. The coronated-NPs with increased protein confirmation changes caused higher genotoxic and cytotoxic effect in human blood cells than the virgin-NPs. On the other hand, virgin-NPs and the NPs isolated from facial scrubs hindered the root growth and caused chromosome aberration (ring formation, C-mitotic and chromosomal breaks, etc.) in root of Allium cepa. At the outset, the present study highlights the urgent need of scrutinization and regulation of NPs use in medical applications and pre-requisition of additional studies for assessing the bio-accumulation and bio-magnification of NPs.

Assessment of anticytotoxic effect of lichen Cladonia foliacae extract on Allium cepa root tips.

The aim of this study is to investigate the protective effect of lichen Cladonia foliacae (Huds.) (CF) on hydrogen peroxide (H2O2)-induced toxicity through cell death, chromosome aberrations, mitotic index, oxidative stress parameters, and DNA damage in a Allium cepa root meristematic cells. Any chemical was not given for control group. Two doses of H2O2 (3 and 7%) were given to the roots for 1 h and the root tips were treated with CF water extract (50 and 100 µL) with increasing times for treatment groups. The roots were taken from control and treatment groups, and mitotic index, cell death, and chromosome aberrations were performed by light microscope. Changing antioxidant capacity of roots was revealed by FRAP and TEAC assay. Also, DNA damage was measured by comet assay and RAPD-PCR technique. Chromosome aberration values were obtained with increasing concentrations with longer treatment times, such as chromosome bridge, vagrant, and polyploidy in both groups. Increasing exposure doses of H2O2 caused decreasing mitotic index values at 72 h. TEAC and FRAP assay demonstrated that roots' capacity of antioxidant was altered by increasing concentrations of H2O2. The tail DNA% and tail length significantly increased in all exposure times when compared to control group. Three and seven percent of H2O2 caused the genotoxic effect on genetic material at 72 h according to RAPD-PCR technique. Increasing the doses of H2O2 resulted in increased toxicity to all studied parameters of A. cepa, but CF extract altered all changing parameters of A. cepa root cell. The H2O2 tested in this study have cytotoxic and mutagenic potential, but extract of CF was protective against H2O2 caused toxicological changes. But, it did not protect completely in the A. cepa root meristematic cells.

Cytotoxic Assessment of Chromium and Arsenic Using Chromosomal Behavior of Root Meristem in Allium cepa L.

A study was performed for phyto-genotoxic assay of chromium (Cr) and arsenic (As) through Allium cepa. Various concentrations (0, 1, 3, 6 and 12 mg L-1) of Cr and As for 48 and 168 h time points exposed to A. cepa. The phytotoxic effects of metal(loid) were evident through inhibited root length and root protein. Metal(loid) toxicity also lead to genotoxic effects, which included depression of mitotic index and increased frequency of chromosomes aberrations like break, fragments, c-metaphase, multipolar arrangements etc. Genotoxic endpoint as progressive frequency of micronuclei in interphase of root meristem cells in treated plants was also observed. This genotoxic endpoint revealed carcinogenic nature of both aforementioned metal(loid). Along with inhibition in root length and protein content, depression in mitotic index as well as stimulation of various abnormality in mitotic cell division indicated that both metal(loid) are hazardous in nature and causing harmful effect on the environment.

Reliability of plant root comet assay in comparison with human leukocyte comet assay for assessment environmental genotoxic agents.

Comet assay is an efficient test to detect genotoxic compounds based on observation of DNA damage. The aim of this work was to compare the results obtained from the comet assay in two different type of cells extracted from the root tips from Lactuca sativa L. and human blood. For this, Spent Pot Liner (SPL), and its components (aluminum and fluoride) were applied as toxic agents. SPL is a solid waste generated in industry from the aluminum mining and processing with known toxicity. Three concentrations of all tested solutions were applied and the damages observed were compared to negative and positive controls. It was observed an increase in the frequency of DNA damage for human leukocytes and plant cells, in all treatments. On human leukocytes, SPL induced the highest percentage of damage, with an average of 87.68%. For root tips cells of L. sativa the highest percentage of damage was detected for aluminum (93.89%). Considering the arbitrary units (AU), the average of nuclei with high levels of DNA fragmentation was significant for both cells type evaluated. The tested cells demonstrated equal effectiveness for detection of the genotoxicity induced by the SPL and its chemical components, aluminum and fluoride. Further, using a unique method, the comet assay, we proved that cells from root tips of Lactuca sativa represent a reliable model to detect DNA damage induced by genotoxic pollutants is in agreement of those observed in human leukocytes as model. So far, plant cells may be suggested as important system to assess the toxicological risk of environmental agents.

Genotoxicity assessment of pulp and paper mill effluent before and after bacterial degradation using Allium cepa test.

A lignin peroxidases-producing Serratia liquefaciens was used for bioremediation of pulp and paper (P&P) mill effluent. The treatment led to reduction of chemical oxygen demand (COD), colour, lignin and phenolic content by 84%, 72%, 61% and 95%, respectively. The effluent detoxification was studied by genotoxicity assays using Allium cepa L. (onion) root tip cells. Genotoxicity studies included measuring mitotic index (MI), chromosomal aberrations (CA) and nuclear abnormalities (NA) in root tip cells following treatment with 25, 50, 75 and 100% (v/v) of effluent. The root tip cells grown in untreated effluent showed a significant decrease in MI from 69% (control) to 32%, 27%, 22% and 11% at 25%, 50%, 75% and 100% effluent concentration, respectively. This indicated that the untreated effluent was highly cytotoxic in nature. Further, root tip cells, when treated with different concentrations of effluent showed various CA and NA including c-mitosis, stickiness, chromosome loss, chromosome break, anaphase bridge, multipolar anaphase, vagrant chromosomes, micronucleated and binucleated cells. The MI observed in root tip cells grown in bacterial treated effluents at similar concentrations (25, 50, 75 and 100% v/v) showed an increase of 33%, 36%, 42% and 66%. CA showed a substantial decrease and in some instances, complete absence of CA was also observed. The findings suggest that S. liquefaciens culture could be a potential bacterial culture for bioremediation of P&P mill effluent, as it is effective in substantial lowering of pollutants load as well as reduces the cytotoxic and genotoxic effects of effluent.

Forskolin: genotoxicity assessment in Allium cepa.

Forskolin, a diterpene, 7ß-acetoxy-8,13-epoxy-1α,6ß,9α-trihydroxy-labd-14-en-11-one (C22H34O7) isolated from Coleus forskohlii, exerts multiple physiological effects by stimulating the enzyme adenylate cyclase and increasing cyclic adenosine monophosphate (cAMP) concentrations. Forskolin is used in the treatment of hypertension, congestive heart failure, eczema, and other diseases. A cytogenetic assay was performed in Allium cepa to assess possible genotoxic effects of forskolin. Forskolin was tested at concentrations 5-100 µM for exposure periods of 24 or 48 h. Treated samples showed significant reductions in mitotic index (p < 0.05) and increases in the frequency of chromosome aberrations (p < 0.01) at both exposure times. The treated meristems showed chromosome aberrations including sticky metaphases, sticky anaphases, laggard, anaphase bridges, micronuclei, polyploidy, fragments, breaks, and C-mitosis. Forskolin may cause genotoxic effects and further toxicological evaluations should be conducted to ensure its safety.

Assessment of cytotoxic and genotoxic potential of pyracarbolid by Allium test and micronucleus assay.

The present study evaluates the cytotoxic and genotoxic potential of pyracarbolid using both micronuleus (MN) assay, in human lymphocytes, and Allium cepa assay, in the root meristem cells. In Allium test, EC50 value was determined in order to selecting the test concentrations for the assay and the root tips were treated with 25 ppm (EC50/2), 50 ppm (EC50) and 100 ppm (EC50 × 2) concentrations of pyracarbolid. One percent of dimethyl sulphoxide (DMSO) and methyl methane sulfonate (MMS) were used as negative and positive controls, respectively. In the micronucleus assay, the cultures were treated with four concentrations (250, 500, 750 and 1000 µg/ml) of pyracarbolid for 24 and 48 h, negative and positive controls were also used in the experiment parallely. The results showed that mitotic index (MI) significantly reduced with increasing the pyracarbolid concentration at each exposure time. It was also obtained that prophase and metaphase index decreased significantly in all concentration at each exposure time. Anaphase index decreased as well and results were found to be statistically significant, except 24 h. A significant increase was observed in MN frequency in all concentrations and both treatment periods when compared with the controls. Pyracarbolid also caused a significant reduction in the cytokinesis block proliferation index (CBPI) in all concentration and both exposure time.

Assessment of genotoxicity and acute toxic effect of the imatinib mesylate in plant bioassays.

Imatinib mesylate (IM) is at present one of the most widely used cytostatic drugs in developed countries but information on its ecotoxicological activities is scarce. This article describes the results of the first investigation in which genotoxic and acute toxic properties of the drug were studied in higher plants. IM was tested in two widely used plant bioassays namely in micronucleus (MN) assays with meiotic tetrad cells of Tradescantia (clone #4430) and in mitotic root tip cells of Allium cepa. Additionally, acute toxic effects (inhibition of cell division and growth of roots) were monitored in the onions. Furthermore, we studied the impact of the drug on the fertility of higher plants in pollen abortion experiments with three wildlife species (Chelidonium majus, Tradescantia palludosa and Arabidopsis thaliana). In MN assays with Tradesacantia a significant effect was seen with doses ⩾10µM; the Allium MN assay was even more sensitive (LOEL⩾1.0µM). A significant decrease of the mitotic indices was detected at levels ⩾10µM in the onions and reduction of root growth with ⩾100µM. In the pollen fertility assays clear effects were observed at doses ⩾147.3mgkg(-1). Data concerning the annual use of the drug in European countries (France, Germany, Slovenia) enable the calculation of the predicted environmental concentration (PEC) values which are in the range between 3.3 and 5.0ngL(-1). Although comparisons with the genotoxic potencies of other commonly used cytostatic drugs and with highly active heavy metal compounds show that IM is an extremely potent genotoxin in higher plants, it is evident that the environmental concentrations are ⩾5 orders of magnitude lower as the levels which are required to cause adverse effects.

Improvement of Vicia-micronucleus test for assessment of soil quality: a proposal for international standardization.

The Viciafaba root tip micronucleus test is one of the most employed plant genotoxicity assays, and has been used on various types of contaminated materials. This test has been standardized by AFNOR, the French member organization of ISO. However, this test is usually performed with a water extraction step but soil genotoxicity assessment would be more relevant when performed directly in the soil itself. In order to harmonize these protocols, an ISO standard for the V.faba micronucleus test in both liquid phase (exposure of plants to different liquid matrix, including soil water extracts) and solid phase (direct exposure of plants to the soil) would be very useful. In this context, we compared two exposure durations in the solid phase (48 h and 5 d) for the V.faba micronucleus test with two different well-known genotoxicants, maleic hydrazide and copper sulfate. We concluded that these two durations induced equivalent sensitivity: the micronucleus frequency was significantly increased with 5 µmol maleic hydrazide per kg dry soil and with 2 mmol copper sulfate per kg dry soil with both exposure durations. However, exposing roots to soil during 48 h is more practical. Moreover, organically and conventionally cultured seeds were employed to determine whether the seed provenance influenced the test sensitivity. Organic seeds were less sensitive to copper, possibly because copper-based treatments are permitted, and often applied, in organic farms. Therefore, in the absence of completely non-treated seeds, organically-cultured seeds did not appear to offer any advantages over conventional seeds.

[Method of radiocapacity factor assessment in study of cross adaptations of plants].

Adaptation of plants to the action of gamma-irradiation and cadmium chloride has been studied in the experiments on water culture of maize plants. A new method of registration of the biological object state at the conditions of the stress-factor action - "the method of radiocapacity factor" based on the measurement of the culture medium radio-activity during the incubation process of vegetative objects has been developed. The method offered has allowed us to estimate in dynamics an integrated condition of the root system exposed to stimulating and inhibiting doses of acute gamma-irradiation. Application of the pattern of radio-adaptive response has allowed us to reveal it using both a conventional technique - by registering the values of growing parameters, and the radiocapacity factor method.

Assessment of arsenic toxicity using Allium/Vicia root tip micronucleus assays.

Arsenic is ubiquitous in the environment and is a potential human carcinogen. Its carcinogenicity has been demonstrated in several models. In this study, broad bean (Vicia faba L.) and common onion (Allium cepa L.), two plant species which are commonly used for detecting the genotoxic effects of environmental pollutants, were used to measure possible genotoxic effect of arsenite (0.3-30 mg/l). Present results showed that arsenite (As(III)) induced micronuclei (MN) formation in both Allium and Vicia root tips. MN frequency significantly increased in Vicia root cells exposed to 0.3-10 mg/l arsenite and in Allium root cells exposed to 1-30 mg/l arsenite, which indicated that Vicia root tip cells are more sensitive to arsenite than Allium. Mitotic index (MI) decreased in a concentration-dependent manner and showed significant differences in Vicia/Allium roots among treatments and the control, after exposure to 1-30 mg/l arsenite for at least 4 h. In the present study, MN frequency was positively associated with lipid peroxidation, which indicated that arsenite exposure can induce oxidative stress, cytotoxicity and genotoxicity in plant cells. The results also suggested that Vicia/Allium root micronucleus (MN) assays are simple, efficient and reproducible methods for the genotoxicity monitoring of arsenic water contamination.

Effects of cadmium on root apical meristems of Pisum sativum L.: cell viability, cell proliferation and microtubule pattern as suitable markers for assessment of stress pollution.

By studying the effects of four concentrations of cadmium (0.25, 2.5, 25, 250microM) on Pisum sativum L. roots, we compared parameters generally used in short-term tests for environmental monitoring - root length, mitotic index, occurrence of mitotic aberrations - with less explored parameters related to meristem activity, such as apex size and viability, percentage of DNA-synthesizing cells and microtubule alterations. The results show that low cadmium concentrations caused a reduction of root growth, which is directly related to reduction of apex length, mitotic activity and percentage of DNA-synthetizing cells. The microtubular cytoskeleton was highly sensitive to cadmium, as microtubule alterations appeared after treatment with the lowest cadmium concentration, pointing to microtubules or microtubule-associated proteins, among the main targets of cadmium. In contrast, cell viability was a less sensitive parameter, as it decreased only upon treatment with the highest cadmium concentrations. The different sensitivities of the parameters examined in this work support the use of different endpoints for assessment of risk from polluted soils and waters.

[Assessment of phyto- and cytotoxic effects of heavy metals and aluminum compounds using onion apical root meristem]. / Otsenka fito- i tsitotoksicheskoi aktivnosti soedinenii tiazhelykh metallov i aliuminiia s pomoshch'iu kornevoi apikal'noi meristemy luka.

The effects of different concentrations (10(-6)-10(-3) M) of salts of six metals (cadmium, lead, nickel, aluminum, copper, and zinc) on the root growth of onion (Allium cepa L.) seedling and cell division, chromosome and nucleus morphology in root tip cells were studied. The obtained results showed that tested compounds inhibit the root growth, reduce the mitotic activity of meristem cells and cause the chromosome and nucleus irregularities. On the basis of these data two rows of metal salt toxicity were proposed--for effective concentrations (EC50) of toxic action: CuSO4 > CdCl2 > NiSO4 > Pb(CH3COO)2 > Al(NO3)3 > ZnSO4, and for sublethal and lethal effects of investigated substances: CuSO4 > Pb(CH3COO)2 > CdCl2 > ZnSO4 > NiSO4 > Al(NO3)3.

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 F1) 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 of 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 microns and the total length of the 2n complement of Vicia is 9.32 microns. 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 F1 region. Higher efficiency was also demonstrated when the MCN frequencies were scored from the F1 cells in both Allium and Vicia treated with formaldehyde (FA), mitomycin C (MMC), and maleic hydrazide (MH). The results indicated that scoring of MCN frequencies from the F1 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.(ABSTRACT TRUNCATED AT 400 WORDS)

Assessment of the genotoxicity potential of the nematicide insecticide carbofuran in wheat cells

Carbofuran (Furadan), an insecticide-nematicide, is widely used for seed treatment in Brazil, against pests in crops such as wheat, rice and corn. It was assessed for its cytotoxic and or clastogenic potential in root meristems of Triticum aestivum (tested in vivo). Seed samples (1OO grams each) were individually treated with one, two, four and eight liters of the pure commercial product/lOO kg seed and germinated on three substrates: virgin soil, sterilized soil and growth chamber (on paper). For all treatments, no cytotoxic or clastogenic effects were observed in the meristem root cells.