The environmental fate and behaviour of titanium dioxide (TiO2) nanoparticles is a rapidly expanding area of research. There is a paucity of information regarding toxic effect of TiO2 nanoparticles in plants and to certain extent in humans. The present study focuses on the effect of exposure of TiO2 nanoparticles in two trophic levels, plant and human lymphocytes. The genotoxicity of TiO2 nanoparticles was evaluated using classical genotoxic endpoints, comet assay and DNA laddering technique. DNA damaging potential of TiO2 nanoparticles in Allium cepa and Nicotiana tabacum as representative of plant system could be confirmed in the comet assay and DNA laddering experiments. In Allium micronuclei and chromosomal aberrations correlated with the reduction in root growth. We detected increased level of malondialdehyde (MDA) concentration at 4mM (0.9μM) treatment dose of TiO2 nanoparticles in Allium cepa. This indicated that lipid peroxidation could be involved as one of the mechanism leading to DNA damage. A comparative study of the cytotoxic and genotoxic potential of TiO2 nanoparticles and bulk TiO2 particles in human lymphocytes also reveal interesting results. While TiO2 nanoparticles were found to be genotoxic at a low dose of 0.25mM followed by a decrease in extent of DNA damage at higher concentrations; bulk TiO2 particles reveal a more or less dose dependent effect, genotoxic only at dose 1.25mM and above. The study thus confirms the genotoxic potential of TiO2 nanoparticles in both plant and human lymphocytes. © 2010 Elsevier Ltd.

MAUMITA BANDYOPADHYAY

Botany

M GHOSH

A MUKHERJEE

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Chemosphere

Titanium dioxide (TiO2) or titania has demonstrated excellent potential for commercial use in various arenas, such as in the paint, in pharmaceuticals and food industry. However information on the genotoxic potential of rutile form of TiO2-NP after repeated (28 days) low dose oral exposure in major organs of the reticuloendothelial system (liver, spleen, bone marrow, lymph nodes) is not known. In this study Swiss albino male mice were gavaged TiO2-NP at sub-acute concentration (0.2, 0.4 and 0.8 mg/kg body weight) over a period of 28 days. Results revealed that TiO2-NP administered was of rutile form with mean average size of 25 nm by transmission electron microscopy. The values of PDI and Zeta potential from DLS of TiO2-NP in suspension specified that the nanomaterial was stable without much agglomeration. Chromosomal aberration assay showed that TiO2-NP was genotoxic and cytotoxic. DNA damage evaluation by comet assay confirmed that long term exposure to TiO2-NP at low concentrations can induce genotoxicity systemically in organs, such as liver, spleen, and thymus cells. Structural chromosomal aberration test from bone marrow cells revealed the clastogenicity of TiO2-NP at sub chronic low concentrations. Further in vivo studies are needed to elucidate the underlying mechanisms at the molecular level. © 2019, Archana Sharma Foundation of Calcutta.

Nucleus (India)

Genotoxicity analysis of rutile titanium dioxide nanoparticles in mice after 28Â days of repeated oral administration

Nanoparticles (NPs) are an emerging environmental threat. However, studies of NPs in different environmental components are limited. In this review, we discuss studies that have evaluated the genotoxicity of NPs in higher plants. Among the 29 studies reviewed, silver NPs were most studied (n = 7 articles), with fewer studies reporting the genotoxicity of carbon nanotubes (n = 3), titanium dioxide NPs (n = 4), and zinc oxide NPs (n = 3). Most of the genotoxicity studies were performed in the model plant systems Allium sp (n = 22), Nicotiana sp (n = 4) and Vicia sp (n = 4) using chromosome aberration (n = 22), micronucleus (n = 15) and comet assays (n = 14). Genotoxicity was observed in most of the studies; however, many studies did consider key determinants of NP toxicity such as particle characterization, dissolution, and uptake. From this review, we propose a set of guidelines that should be considered when reporting results of NP toxicity in plants. © 2019 Elsevier B.V.

Fulltext

Mutation Research - Genetic Toxicology and Environmental Mutagenesis

Genotoxicity of engineered nanoparticles in higher plants

Synergistic interaction of nitric oxide (NO) and reactive oxygen species (ROS) is essential to initiate cell death mechanisms in plants. Though autophagy is salient in either restricting or promoting hypersensitivity response (HR)-related cell death, the crosstalk between the reactive intermediates and autophagy during hypersensitivity response is paradoxical. In this investigation, the consequences of Alternaria alternata toxin (AaT) in tobacco BY-2 cells were examined. At 3 h, AaT perturbed intracellular ROS homeostasis, altered antioxidant enzyme activities, triggered mitochondrial depolarization and induced autophagy. Suppression of autophagy by 3-Methyladenine caused a decline in cell viability in AaT treated cells, which indicated the vital role of autophagy in cell survival. After 24 h, AaT facilitated Ca2+ influx with an accumulation of reactive oxidant intermediates and NO, to manifest necrotic cell death. Inhibition of NO accumulation by 2-(4-Carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO) decreased the level of necrotic cell death, and induced autophagy, which suggests NO accumulation represses autophagy and facilitates necrotic cell death at 24 h. Application of N-acetyl-L-cysteine at 3 h, confirmed ROS to be the key initiator of autophagy, and together with cPTIO for 24 h, revealed the combined effects of NO and ROS is required for necrotic HR cell death. © 2019, The Author(s).

Scientific Reports

Nitric oxide and ROS mediate autophagy and regulate Alternaria alternata toxin-induced cell death in tobacco BY-2 cells

The effect of cerium oxide nanoparticle (CeNP) in plants has elicited substantial controversy. While some investigators have reported that CeNP possesses antioxidant properties, others observed CeNP to induce reactive oxygen species (ROS). In spite of considerable research carried out on the effects of CeNP in metazoans, fundamental studies that can unveil its intracellular consequences linking ROS production, autophagy and DNA damage are lacking in plants. To elucidate the impact of CeNP within plant cells, tobacco BY-2 cells were treated with 10, 50 and 250 µg ml-1 CeNP (Ce10, Ce50 and Ce250), for 24 h. Results demonstrated concentration-dependent accumulation of Ca2+ and ROS at all CeNP treatment sets. However, significant DNA damage and alteration in antioxidant defence systems were noted prominently at Ce50 and Ce250. Moreover, Ce50 and Ce250 induced DNA damage, analysed by comet assay and DNA diffusion experiments, complied with the concomitant increase in ROS. Furthermore, to evaluate the antioxidant property of CeNP, treated cells were washed after 24 h (to minimise CeNP interference) and challenged with H2O2 for 3 h. Ce10 did not induce genotoxicity and H2O2 exposure to Ce10-treated cells showed lesser DNA breakage than cells treated with H2O2 only. Interestingly, Ce10 provided better protection over N-acetyl-L-cysteine against exogenous H2O2 in BY-2 cells. CeNP exposure to transgenic BY-2 cells expressing GFP-Atg8 fusion protein exhibited formation of autophagosomes at Ce10. Application of vacuolar protease inhibitor E-64c and fluorescent basic dye acridine orange, further demonstrated accumulation of particulate matters in the vacuole and occurrence of acidic compartments, the autophagolysosomes, respectively. BY-2 cells co-treated with CeNP and autophagy inhibitor 3-methyladenine exhibited increased DNA damage in Ce10 and cell death at all assessed treatment sets. Thus, current results substantiate an alternative autophagy-mediated, antioxidant and geno-protective role of CeNP, which will aid in deciphering novel phenomena of plant-nanoparticle interaction at cellular level.

Mutagenesis

Role of cerium oxide nanoparticle-induced autophagy as a safeguard to exogenous H2O2-mediated DNA damage in tobacco BY-2 cells

Leaching of heavy metals from coal fly ash dumpsites is an environmental threat often polluting both groundwater and surface water. This led to a detailed investigation on the cyto-genotoxicity and oxidative stress associated with the fly ash leachate (FL). Allium cepa L. bulbs were exposed to three concentrations of FL. Response to FL resulted in a reduction of root growth, inhibition of cell viability by up to 50%, and decrease in mitotic indices (control: 10.27; FA:water 1:4–4.52) with increased frequency of chromosome aberrations (5.7 fold) and bi-nucleate cells. Results of comet assay indicated that approximately sixfold increase in genotoxicity of FL was congruent with the endpoints of oxidative stress evaluated. The malondialdehyde content, superoxide dismutase, guaiacol peroxidase and glutathione-S-transferase activities were elevated in the treated plants in a dose dependent manner. The elemental analysis of FL showed the presence of heavy metals like cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), cadmium (Cd), nickel (Ni), lead (Pb) and zinc (Zn). The study demonstrated that FL can cause adverse effects to the plants. Therefore, the disposal of coal fly ash should be handled with caution and prevented from contaminating the surroundings. © 2017 Informa UK Limited, trading as Taylor & Francis Group.

Archives of Agronomy and Soil Science

Hazard identification of coal fly ash leachate using a battery of cyto-genotoxic and biochemical tests in Allium cepa

Fly ash is a by-product of coal-fired electricity generation plants. Its utilization and disposal is of utmost importance. Using onion (Allium cepa ) root tip system, the present study was carried out to evaluate the potential toxic and genotoxic effects of fly ash, collected from a thermal power plant in West Bengal, India. Prior to testing, the collected fly ash sample was mixed with sand in different proportions. Allium bulbs were allowed to germinate directly in fly ash and after five days the germinating roots were processed for the Allium test. Additionally, the Allium test was adapted for detecting DNA damage through comet assay. The results from the Allium test indicate that fly ash at 100% concentration inhibits root growth and mitotic indices; induces binucleated cells as a function of the proportion, but is not toxic at very low concentration. In the comet assay, a statistical increase for DNA strand breaks was found only at higher concentrations. The sample was analyzed by flame atomic absorption spectrometer for Zn, Pb, Cu, Ni, Cd and As, whose presence could partly be responsible for the toxicity of fly ash. The study concludes that the classical Allium test can give a more comprehensive data when done in combination with the comet assay, which is faster, simpler and independent of mitosis. Also when fly ash is used for other purposes in combination with soils, it should be judiciously used at very low concentrations in order to protect the ecosystem health from any potential adverse effects. © Springer Science+Business Media B.V. 2008.

Environmental Monitoring and Assessment

Evaluation of genotoxicity of coal fly ash in Allium cepa root cells by combining comet assay with the Allium test

Low-calorie sweeteners are chemicals that offer the sweetness of sugar without the calories. Consumers are increasingly concerned about the quality and safety of many products present in the diet, in particular, the use of low-calorie sweeteners, flavorings, colorings, preservatives, and dietary supplements. In the present study, we evaluated the mutagenicity of the three low-calorie sweeteners in the Ames/Salmonella/microsome test and their genotoxic potential by comet assay in the bone marrow cells of mice. Swiss albino mice, Mus musculus, were orally administered with different concentrations of aspartame (ASP; 7, 14, 28, and 35 mg/kg body weight), acesulfame-K (ASK; 150, 300, and 600 mg/kg body weight), and saccharin (50, 100, and 200 mg/kg body weight) individually. Concurrently negative and positive control sets were maintained. The animals were sacrificed and the bone marrow cells were processed for comet assay. The standard plate-incorporation assay was carried with the three sweeteners in Salmonella typhimurium TA 97a and TA 100 strains both in the absence and presence of the S9 mix. The comet parameters of DNA were increased in the bone marrow cells due to the sweetener-induced DNA strand breaks, as revealed by increased comet-tail extent and percent DNA in the tail. ASK and saccharin were found to induce greater DNA damage than ASP. However, none could act as a potential mutagen in the Ames/Salmonella /microsome test. These findings are important, since they represent a potential health risk associated with the exposure to these agents. Copyright © Informa UK, Ltd.

Drug and Chemical Toxicology

Genotoxicity testing of low-calorie sweeteners: Aspartame, acesulfame-K, and saccharin

The effects of CdCl2 and Na2SeO3, administered singly and in combination, were studied on cell division and chromosomal aberrations in root tip cells of Allium sativum L. The frequency of dividing cells was reduced significantly and the number of chromosomal aberrations was enhanced significantly following combined treatment with Cd and Se as compared with treatment with the individual salts. The type of interaction and consequent effects on cytotoxicity depended mainly on the relative concentrations of the two salts used. © 1988 Kluwer Academic Publishers.

Journal	Chemosphere
Publisher	-
ISSN	0045-6535
Open Access	No