Soybean cultivation is widespread in the State of Rio Grande do Sul (RS, Brazil), especially in the city of Espumoso. Soybean workers in this region are increasingly exposed to a wide combination of chemical agents present in formulations of fungicides, herbicides, and insecticides. In the present study, the comet assay in peripheral leukocytes and the buccal micronucleus (MN) cytome assay (BMCyt) in exfoliated buccal cells were used to assess the effects of exposures to pesticides in soybean farm workers from Espumoso. A total of 127 individuals, 81 exposed and 46 non-exposed controls, were evaluated. Comet assay and BMCyt (micronuclei and nuclear buds) data revealed DNA damage in soybean workers. Cell death was also observed (condensed chromatin, karyorhectic, and karyolitic cells). Inhibition of non-specific choline esterase (BchE) was not observed in the workers. The trace element contents of buccal samples were analyzed by Particle-Induced X-ray Emission (PIXE). Higher concentrations of Mg, Al, Si, P, S, and Cl were observed in cells from workers. No associations with use of personal protective equipment, gender, or mode of application of pesticides were observed. Our findings indicate the advisability of monitoring genetic toxicity in soybean farm workers exposed to pesticides.

Iron is an essential nutrient for plants. In aerobic conditions, Fe is highly unavailable for plant uptake, and Fe deficiency can be severe in plants grown in calcareous soils. In waterlogged soils, however, Fe availability increases and can reach toxic concentrations. Rice is an important staple crop worldwide and faces iron deficiency or excess, depending on the growth conditions. To contribute to the study of mechanisms involved in response to Fe deficiency and resistance to Fe excess, experiments were carried out with rice cultivars BR-IRGA 409 (I409, susceptible to Fe toxicity) and EPAGRI 108 (E108, resistant to Fe toxicity) grown in culture solutions and submitted to Fe excess, control concentration or deficiency (500, 6.5 or zero mg L-1 Fe, respectively). Analysis of shoot dry weight confirmed the resistance of E108 plants to Fe excess. Mössbauer spectroscopy analysis indicated the presence of four different Fe3+compounds. The parameters obtained match those expected for ferrihydrite, lepidocrocite (and/or citrate) and Fe-nicotianamine. Mineral concentrations were determined using the PIXE (Particle Induced X-Ray Emission) technique. E108 plants had lower Fe concentrations than I409 plants when exposed to excess Fe. Except for lower Mn levels in roots and shoots, the excess of Fe did not result in lower nutrient concentrations in the susceptible cultivar compared to the resistant one. I409 plants seem to be affected directly by Fe toxicity rather than by secondary effects on mineral nutrition, whereas E108 plants seem to make use of the avoidance mechanism in the resistance to Fe overload. Both cultivars responded to Fe deficiency with allocation of P from roots to shoots. In addition to being more resistant to iron overload, E108 plants seem to be more efficient in inducing Fe deficiency responses.

Industrial effluents, agricultural runoff, and municipal wastewaters contain unknown substances and complex mixtures that are released into the environment and can lead to contamination of surface and subsurface waters. In the present report, we have used the alkaline Comet assay and the micronucleus (MN) test to detect the genotoxicity due to multiple sources of pollution in the peripheral blood of two native estuarine fish (mullet and sea catfish) and evaluated possible interactive genotoxic effects from multiple contaminants and the seasonal variation of the genotoxicity. Mullet and sea catfish were captured in the Tramandai and Mampituba Rivers in the southern Brazilian state of Rio Grande do Sul. Reference animals were obtained from the Armazem lagoon. Fish captured in the two estuaries during the four seasons over a period of 2 years had increased levels of DNA damage and MN frequencies relative to the reference fish. In general, the alkaline Comet assay was more sensitive to the genotoxicity of the river contaminants than the MN test. The Comet assay demonstrated significant differences in fish captured at different seasons and at the two river sites, while the MN test showed significant differences only for the annual average for mullet from both sites and fish from the control site. The increases in DNA damage appear to be related to the increase in the number of people in the towns close to the study areas during the warm spring and summer seasons. Although no specific cause-effect relationships were established, comparison of the chemical contaminants and physical variations in the rivers with the genotoxicity data indicate that there may be some association between hydrocarbons, metals, pH, and water temperature and the level of damaged cells observed in mullet and sea catfish from the Tramandai and Mampituba estuaries.

In the present work, we have explored the interference effects which arise when H 2 + and H 3 + cluster ions interact with a thin layer of SiO 2 in order to obtain a clear signature of plasmon excitations induced by these energetic projectiles. For this purpose, high-energy-resolution experiments were carried out as a function of the incoming projectile energy, covering an energy range between 40 and 200 keV/ amu. The ratio R n between the energy loss of the cluster and the sum of the energy loss of its constituents has a steep increase between 70 and 100 keV/ amu for both cluster ions, which is associated with the plasmon excitation threshold.

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