Physiological and agronomical traits effects of titanium dioxide nanoparticles in seedlings of Solanum lycopersicum L.

BACKGROUND: Titanium dioxide nanoparticles (TiO2 NPs) have been reported to have contrasting effects on plant physiology, while their effects on sugar, protein, and amino acid metabolism are poorly understood. In this work, we evaluated the effects of TiO2 NPs on physiological and agronomical traits of tomato (Solanum lycopersicum L.) seedlings. Tomato seeds were treated with TiO2 NPs (1000 and 2000 mg L- 1), TiO2 microparticles (µPs, 2000 mg L- 1) as the size control, and ultrapure water as negative control. RESULTS: The dry matter of stems (DMs), leaves (DMl) and total dry matter (DMt) decreased as particle concentration increased. This trend was also observed in the maximum quantum yield of light-adapted photosystem II (PSII) (Fv´/Fm´), the effective quantum yield of PSII (ΦPSII), and net photosynthesis (Pn). The concentrations of sugars, total soluble proteins, and total free amino acids were unaffected, but there were differences in the daily dynamics of these compounds among the treatments. CONCLUSION: Our results suggest that treating tomato seeds with TiO2 might affect PSII performance, net photosynthesis and decrease biomass production, associated with a concentration- and size-related effect of TiO2 particles.

Assessing the ecological risk of active principles used currently by freshwater fish farms.

The global aquaculture industry has grown exponentially in recent years using to control of infections and diseases, a variety of veterinary drugs (VMP) are used, including antibiotics, antifungals and antiparasitics, which have different routes of emission, environmental persistence and side effects to aquatic organisms, becoming one of the main concerns in its use of veterinary drugs (VMP) and its potential toxicological impact on the environment, in this context, Chile is considered one of the main salmon producers. Ecological risk assessment of active principles used infreshwater fish farms worldwide and in Chile were investigated. We recollect a physical - chemical properties of active principles used by fish farms and we could estimate the relative hazard a priori. Later active principles grouped as antibiotics (n = 6), antiparasitics (n = 5), anesthetics (n = 3), and disinfectants (n = 7) were assessed using a mass balance model based on fugacity was developed for each active principle under treatments via immersion and food administration in fish, while a volumetric model for disinfectants and sodium chloride was used for estimating the predicted environmental concentration (PEC), under a real smolt farming scenario in fish farms. Ecotoxicological data were collected from open literature to predict the no-effect concentration (PNEC). The ecological risk assessment was characterized using a risk quotient (RQ = PEC/PNEC) based in two assessment tiers. Results revealed that 12 active ingredients showed a high risk (RQ ≥ 1), thus indicating that adverse effects could occur and further investigation with measured concentrations in the field are required to reduce exposure in surface waters.

Hybrid porous silicon/green synthetized Ag microparticles as potential carries for Ag nanoparticles and drug delivery.

In the present work, the fabrication of hybrid porous silicon/green synthetized Ag microparticles was shown and the potential use as carriers for Ag nanoparticles and drug delivery was explored. Hybrid microparticles were fabricated by incorporating green synthetized Ag nanoparticles into porous silicon matrix. The main physicochemical characteristics of the hybrid systems were studied by several techniques including UV-vis spectroscopy, TEM, SEM, XRD and XPS. The toxicology of these hybrid systems was investigated by cell viability, MTT, and comet assays. In addition, the possibility to aggregate different drug to use as drug delivery system was demonstrated by using florfenicol as drug model, due to its importance in salmon industry. The experimental results showed the potential to use these hybrid systems as carries for drug delivery in salmon industry.

The Wing-Spot and the Comet Tests as Useful Assays for Detecting Genotoxicity in Drosophila.

In spite of its pioneer use in detecting mutational processes, Drosophila still plays an important role in those studies aiming to detect and quantify the induction of DNA damage. Here we describe two assays, one detecting primary damage (the Comet assay) and the other detecting somatic mutation and recombination effects (wing-spot test). It is important to emphasize that somatic recombination is a key event in cancer development and no assays exist at present to detect and quantify somatic recombination processes, other than the spot tests developed in Drosophila.

Assessing the effectiveness of green synthetized silver nanoparticles with Cryptocarya alba extracts for remotion of the organic pollutant methylene blue dye.

In the present work, silver nanoparticles (AgNPs) synthetized with Cryptocarya alba (Peumo) leaf extract were studied. The fabrication method was fast, low cost, and eco-friendly, and the final properties of AgNPs were determined by experimental parameters, such as AgNO3 and Peumo extract concentrations used. Setting suitable experimental conditions, crystalline AgNPs with apparent spherical forms and average diameter around 3.5 nm were obtained. In addition, the capability of synthesized Peumo-AgNPs to remove methylene blue dye (MB) in aqueous solution as well as their catalytic effectiveness was also investigated. The results showed that green synthesized AgNPs can remove fast and effectively the MB dye from aqueous medium by itself, but better results were found acting like catalyst by using sodium borohydride (NaBH4) in the reaction. In addition, this green nanomaterial can be recycling several times maintaining initial properties for removal of MB. Thus, AgNPs synthetized with Peumo leaf extracts could be an excellent catalyst candidate for degradation of blue methylene dye in chemical industries.

Genotoxicity of Copper and Nickel Nanoparticles in Somatic Cells of Drosophila melanogaster.

Copper and nickel nanoparticles (Cu-NPs and Ni-NPs, respectively) are used in a variety of industrial applications, such as semiconductors, catalysts, sensors, and antimicrobial agents. Although studies on its potential genotoxicity already exist, few of them report in vivo data. In the present study we have used the wing-spot assay in Drosophila melanogaster to determine the genotoxic activity of Cu-NPs and Ni-NPs, and these data have been compared with those obtained with their microparticle forms (MPs). Additionally, a complete physical characterization of NPs using transmission electronic microscopy (TEM), dynamic light scattering (DLS), and laser Doppler velocimetry (LDV) techniques was also performed. Results obtained with Cu-NPs and Cu-MPs indicate that both failed to induce an increase in the frequency of mutant spots formation in the wings of the adults, suggesting a lack of genotoxicity in somatic cells of D. melanogaster. However, when Ni-NPs and Ni-MPs were evaluated, a significant increase of small single spots and total mutant spots was observed only for Ni-NPs (P<0.05) at the highest dose assessed. Thus, the genotoxicity of Ni-NPs seem to be related to their nanoscale size, because no genotoxic effects have been reported with their microparticles and ions. This study is the first assessing the in vivo genotoxic potential of Cu-NPs and Ni-NPs in the Drosophila model.

Antimutagenic evaluation of traditional medicinal plants from South America Peumus boldus and Cryptocarya alba using Drosophila melanogaster.

Peumus boldus Mol. ("Boldo") and Cryptocarya alba Mol. Looser ("Peumo") are medicinal shrubs with wide geographical distribution in South America. Their leaves and fruits are commonly used in traditional medicine because they exhibit natural medicinal properties for treatment of liver disorders and rheumatism. However, there are no apparent data regarding potential protective effects on cellular genetic components. In order to examine potential mutagenic and/or antimutagenic effects of these medicinal plants, the Drosophila melanogaster (D. melanogaster) wing-spot test was employed. This assay detects a wide range of mutational events, including point mutations, deletions, certain types of chromosomal aberrations (nondisjunction), and mitotic recombination. Qualitative and quantitative analyses of phenolic and anthocyanin compounds were carried out using biochemical and high-performance liquid chromatography methodologies. In addition, the antioxidant capacity of P. boldus and C. alba leaf extracts was also analyzed. P. boldus and C. alba extracts did not induce significant mutagenic effects in the D. melanogaster model. However, simultaneous treatment of extracts concurrently with the mutagen ethyl methane sulphonate showed a decrease of mutant spots in somatic cells of D. melanogaster, indicating desmutagenic effects in this in vivo model. Flavonoids and anthocyanins were detected predominantly in the extracts, and these compounds exerted significant antioxidant capacity. The observed antimutagenic effects may be related to the presence of phytochemicals with high antioxidant capacity, such as flavonoids and antohocyanins, in the extracts.

Genotoxic and oxidative stress potential of nanosized and bulk zinc oxide particles in Drosophila melanogaster.

Zinc oxide nanoparticles (ZnONP) are manufactured on a large scale and can be found in a variety of consumer products, such as sunscreens, lotions, paints and food additives. Few studies have been carried out on its genotoxic potential and related mechanisms in whole organisms. In the present study, the in vivo genotoxic activity of ZnONP and its bulk form was assayed using the wing-spot test and comet assay in Drosophila melanogaster Additionally, a lipid peroxidation analysis using the thiobarbituric acid assay was also performed. Results obtained with the wing-spot test showed a lack of genotoxic activity of both ZnO forms. However, when both particle sizes were tested in the comet assay using larvae haemocytes, a significant increase in DNA damage was observed for ZnONP treatments but only at the higher dose applied. In addition, the lipid peroxidation assay showed significant malondialdehyde (MDA) induction for both ZnO forms, but the induction of MDA for ZnONP was higher for the ZnO bulk, suggesting that the observed DNA strand breaks could be induced by mediated oxidative stress. The overall data suggest that the potential genotoxicity of ZnONP in Drosophila can be considered weak according to the lack of mutagenic and recombinogenic effects and the induction of primary DNA damage only at high toxic doses of ZnONP. This study is the first assessing the genotoxic and oxidative stress potential of nano and bulk ZnO particles in Drosophila.

Genotoxicity of copper oxide nanoparticles in Drosophila melanogaster.

Copper oxide nanoparticles (CuONPs) are used as semiconductors, catalysts, gas sensors, and antimicrobial agents. We have used the comet and wing-spot assays in Drosophila melanogaster to assess the genotoxicity of CuONPs and ionic copper (CuSO4). Lipid peroxidation analysis was also performed (Thiobarbituric Acid Assay, TBARS). In larval hemocytes, both CuONPs and CuSO4 caused significant dose-dependent increases in DNA damage (comet assay). In the wing-spot assay, an increase in the frequency of mutant spots was observed in the wings of the adults; CuONPs were more effective than was CuSO4. Both agents induced TBARS; again, CuONPs were more active than was CuSO4. The results indicate that CuONPs are genotoxic in Drosophila, and these effects may be mediated by oxidative stress. Most of the effects appear to be related to the presence of copper ions.

Genotoxic testing of titanium dioxide anatase nanoparticles using the wing-spot test and the comet assay in Drosophila.

Titanium dioxide nanoparticles (TiO2 NPs) are widely used for preparations of sunscreens, cosmetics, food and personal care products. However, the possible genotoxic risk associated with this nano-scale material exposure is not clear, especially in whole organisms. In the present study, we explored the in vivo genotoxic activity of TiO2 NPs as well as their TiO2 bulk form using two well-established genotoxic assays, the wing spot test and the comet assay in Drosophila melanogaster. To determine the extent of tissue damage induced by TiO2 NPs in Drosophila larvae, the trypan blue dye exclusion test was also applied. Both compounds were supplied to third instar larvae by ingestion at concentration ranging from 0.08 to 1.60 mg/mL. The results obtained in the present study indicate that TiO2 NPs can reach and induce cytotoxic effects on midgut and imaginal disc tissues of larvae, but they do not promote genotoxicity in the wing-spot test of Drosophila. However, when both nano- and large-size forms of TiO2 were evaluated with the comet assay in Drosophila hemocytes, a significant increase in DNA damage, with a direct dose-response pattern, was observed for TiO2 NPs. The results obtained with the comet assay suggest that the primary DNA damage associated with TiO2 NPs exposure in Drosophila could be associated with specific physico-chemical properties of nano-TiO2, since no effects were observed with the bulk form. This study remarks the usefulness of using more than one genetic end-point in the evaluation of the genotoxic potential of nanomaterials.

The wing-spot and the comet tests as useful assays detecting genotoxicity in Drosophila.

In spite of its pioneer use in detecting mutational processes, Drosophila has yet an important role in studies aiming to detect and quantify the induction of DNA damage. Here we describe two assays, one detecting primary damage (the Comet assay) and the other detecting somatic mutation and recombination effects (wing-spot test). It is important to emphasize that somatic recombination is a key event in cancer and no assays exist to detect and quantify somatic recombination processes, other than the spot tests developed in Drosophila.

Genotoxicity testing of two lead-compounds in somatic cells of Drosophila melanogaster.

The in vivo genotoxic activity of two inorganic lead compounds was studied in Drosophila melanogaster by measurement of two different genetic endpoints. We used the wing-spot test and the comet assay. The comet assay was conducted with larval haemocytes. The results from the wing-spot test showed that neither lead chloride, PbCl(2), nor lead nitrate, Pb(NO(3))(2), were able to induce significant increases in the frequency of mutant spots. In addition, the combined treatments with gamma-radiation and PbCl(2) or Pb(NO(3))(2) did not show significant variations in the frequency of the three categories of mutant spots recorded, compared with the frequency induced by gamma-radiation alone. This seems to indicate that the lead compounds tested do not interact with the repair of the genetic damage induced by ionizing radiation. When the lead compounds were evaluated in the in vivo comet assay with haemocytes, Pb(NO(3))(2) was effective in inducing significant increases of DNA damage with a direct dose-response pattern. These results confirm the usefulness of the comet assay with haemocytes as an in vivo model and support the assumption that there is a genotoxic risk associated with lead exposure.

Genotoxic effects of two nickel-compounds in somatic cells of Drosophila melanogaster.

In view of the scarcely available information on the in vivo mutagenic and co-mutagenic activity of nickel, the genotoxic potential of two nickel-compounds, nickel chloride (NiCl(2)) and nickel sulphate (NiSO(4)), was assessed in Drosophila melanogaster by measuring two different genetic endpoints. On the one hand, we used the wing-spot assay, which is based on the principle that the loss of heterozygosity of two suitable recessive markers, multiple wing hairs (mwh) and flare-3 (flr(3)), can lead to the formation of mutant clones in the imaginal disks of larval cells. On the other hand, the in vivo comet assay, which detects single- and double-strand DNA breaks, was also used with larval haemocytes. These cells offer several advantages: they are highly sensitive to genotoxic agents, the sampling and processing methodologies are quite simple and the level of basal DNA damage is relatively low. No significant increases in the frequencies of the three categories of mutant spots (i.e. small single spots, large single spots, and twin spots) were observed in the wing-spot assay; however, NiSO(4) induced significant dose-dependent increases in DNA damage in the comet assay. In addition, the combined treatments with gamma-radiation and NiCl(2) and NiSO(4) showed a slight but significant increase in the frequency of the three categories of mutant spots compared with the frequency induced by gamma-radiation alone, indicating that both nickel compounds have a synergistic interaction. These results support the assumption that both nickel compounds could act as co-mutagens interfering with DNA-repair processes and that the in vivo comet assay is a sensitive and effective method for detecting the DNA damage induced by NiSO(4) in haemocytes of D. melanogaster.

Proposal of an in vivo comet assay using haemocytes of Drosophila melanogaster.

This study presents the first application of an in vivo alkaline comet assay using haemocytes of Drosophila melanogaster larvae. These cells, which play a role similar to that of mammalian blood, can be easily obtained and represent an overall exposure of the treated larvae. To validate the assay, we evaluated the response of these cells to three well-known mutagenic agents: ethyl methanesulfonate (EMS), potassium dichromate (PD), and gamma radiation (γ-irradiation). Third-instar Drosophila larvae were exposed to different concentrations of EMS (1, 2, and 4 mM) and PD (0.5, 1, and 2.5 mM) and to different doses of γ-irradiation (2, 4, and 8 Gγ). Subsequently, haemolymph was extracted from the larvae, and haemocytes were isolated by centrifugation and used in the comet assay. Haemocytes exhibited a significant dose-related increase in DNA damage, indicating that these cells are clearly sensitive to the treatments. These results suggest that the proposed in vivo comet test, using larvae haemocytes of D. melanogaster, may be a useful in vivo assay for genotoxicity assessment.

Genotoxic evaluation of two halonitromethane disinfection by-products in the Drosophila wing-spot test.

Few studies on the genotoxicity of halonitromethanes (HNMs) have been done. This limited information on their potential genotoxic risk gives special relevance to the collection of new data on their potential genotoxic activity. In the present study we have analyzed the genotoxicity of two HNMs namely bromonitromethane (BNM) and trichloronitromethane (TCNM) in the in vivo wing somatic mutation and recombination test in Drosophila, also known as the wing-spot assay. This test is based on the principle that loss of heterozygosis and the corresponding expression of the suitable recessive markers, multiple wing hairs (mwh) and flare-3 (flr(3)), can lead to the formation of mutant clones in larval cells, which are then expressed as spots on the wings of adult flies. BNM and TCNM were supplied to third instar larvae (72+/-4 h-old) at concentrations ranging from 0.1 to 2 mM. The results showed that none of the three categories of mutant spots recorded (small, large, and twin) increased significantly by the treatments, independently of the dose supplied, indicating that the selected HNMs exhibit a lack of genotoxic activity in the wing-spot assay of Drosophila melanogaster. These results contribute to increase the genotoxicity database on the HNMs.

Genotoxic evaluation of two mercury compounds in the Drosophila wing spot test.

Few studies on the genotoxicity of mercury compounds have been carried out in Drosophila melanogaster, most of them focused in the effects on germinal cells, whereas studies in somatic cells are scarce. In the present study we have analyzed for the first time the genotoxic activity of mercury (II) chloride (MC) and methyl mercury (II) chloride (MMC) in the in vivo wing somatic mutation and recombination test in Drosophila, also known as the wing spot assay. This test is based on the principle that loss of heterozygosis and the corresponding expression of the suitable recessive markers, multiple wing hairs (mwh) and flare-3 (flr(3)), can lead to the formation of mutant clones in larval cells, which are then expressed as spots on the wings of adult flies. The mercury compounds were supplied to third instar larvae (72+/-2h old) at concentrations ranging from 1 to 50 microM for mercury chloride (MC) and from 0.5 to 5 microM for methyl mercury chloride (MMC). Both mercury compounds showed high toxicity; however, MMC was more toxic than MC. The results showed that none of the three categories of mutant spots recorded (small, large, and twin) increased significantly by the treatments, independently of the dose supplied, indicating that the mercury compounds tested exhibit a lack of genotoxic activity in the wing spot assay of D. melanogaster. These results contribute to increase the genotoxicity database on the in vivo evaluation of mercury compounds in Drosophila.