NANOCIÊNCIA & NANOTECNOLOGIA

Nanomateriais vêm causando uma revolução na ciência, e sua aplicação na tecnologia está aumentando. Nanopartículas compreendem partículas entre 1 e 100 nanômetros (nm) de tamanho, mas este intervalo pode variar quando relativo à avaliação toxicológica. O uso extensivo e a consequente produção de resíduos de nanomateriais têm levado esses produtos químicos para o meio ambiente, o que causa possíveis contaminações. Portanto, como um assunto interdisciplinar, fez-se, aqui, uma breve revisão sobre alguns aspectos interessantes e contemporâneos da nanotecnologia, especialmente focados em ciências ambientais e da conservação.Palavras-chave: Nanomateriais. Nanotoxicologia. Ecotoxicologia. Dióxido de titânio

Piscine micronucleus test and the comet assay reveal genotoxic effects of Atrazine herbicide in the neotropical fish Rhamdia quelen

Atrazine (ATZ) is an herbicide extensively used around the world to kill weeds. Due to its applicability and benefits in farming, ATZ can easily reach the aquatic ecosystems and, therefore, represent risks for aquatic biota and human populations. The aim of this study was to evaluate the genotoxic effects of ATZ on Rhamdia quelen through the piscine micronucleus test (MNT) and the comet assay in erythrocytes (ECA) and gill cells (GCA), at three different concentrations (2, 10, and 100 μg L-1) in static (SB) and semi-static bioassays (SSB) during 96 hours. In the SB, we observed an increased frequency of nuclear morphological abnormalities at all concentrations and a dose-dependent effect of ATZ on DNA through the ECA. There was no difference among treatments in gills. In the SSB there was no significant difference in MNT, but the ECA showed an increase of DNA breakages at 10 μg L-1 treatment. GCA showed higher DNA damage on fish exposed to 2 and 100 μg L-1. Our results show a trend to dose-dependent genotoxic effect of ATZ, which causes damage to the DNA of Rhamdia quelen even in a concentration considered safe by regulatory agencies

Co-exposure effects of Titanium Dioxide Nanoparticles and Metals on antioxidant systems and DNA in the fish Hoplias intermedius

Metallic nanoparticles are one of the most produced and used engineered nanomaterial and their wide applications lead to environmental contamination. The aquatic environment is the major recipient of wastes containing nanoparticles and other co-occuring contaminants. We aimed to evaluate genotoxic and biochemical effects of acute exposure to nano-TiO2 in the fish Hoplias intermedius and the interaction to metals. Besides assessing the nanoparticles’ physical-chemical properties we performed an acute exposure with 0.1; 1; 10 μg g-1 nano-TiO2, alone and with lead (21 μgg-1) and aluminium (50 μgg-1). A set of biomarkers were evaluated in the liver such as genotoxicity by comet assay and biochemical biomarkers (SOD, CAT, GPx, GSH, EROD, GST). Most of the biomarkers were altered by the metals, and the nanoparticles caused decrease in SOD (0.1 and 1μg g-1), GSH (1μg g-1), and GST (0.1 μg g-1). In co-exposure, some metal effects were attenuated. There was an increase in EROD activity for most co-exposure groups. Nano-TiO2 was not genotoxic in the experimental conditions. We did not observe any increase in DNA breaks in co-exposure, although, nanoparticles changed the response of some biochemical biomarkers

Biochemical and genotoxicity assessment of a polluted urban river using the native fish Astyanax altiparanae Garutti & Britski (Teleostei, Characidae)

Agriculture residues and domestic effluents are contaminants that reach aquatic ecosystems leading to toxic effects to environment and human health. These contaminants impacting mainly developing countries, due to precarious treatment of effluents and lack of legislation in the use of pesticides. Perequê River (South of Brazil) is impacted by pesticides (mainly glyphosate) and domestic effluents. The aims of this study were to analyze the concentration of glyphosate in water and sediments of Perequê River; and to evaluate the sublethal effects of the river contamination in Astyanax altiparanae using biomarkers. A sampling of water, sediment and fish were carried out in Perequê River (November/2016). The samples were collected in two sites, site 1 (S1) that is located on agriculture area and water catchment point; and site 2 (S2) located on the area with a domestic effluents influence. Water and sediment samples were used to glyphosate quantification. Fish were collected and tissues (brain, muscle, liver) were used to biochemical and genetic biomarkers. Glyphosate were quantified in S1, which is impacted by agriculture. Alterations in the liver biomarkers were not observed between the sites. However, the decrease in the AChE activity was observed in the S2, showing that the mixture of contaminants (urban and agriculture contaminants) can lead to anticholinesterasic effects. The sublethal effects observed can be a threat of environmental and human health

Genotoxicity detected during cyanobacteria bloom in a water supply reservoir

The aquatic ecosystems are susceptible to cyanobacterial blooms due to the eutrophication of water bodies caused by human activities. In this study, phytoplankton and cyanotoxins analysis, as well as cellular and genetic biomarkers of toxicity (Allium cepa test - higher plant test system), were evaluated in water samples of Alagados Reservoir during a cyanobacterial bloom in South Brazil. The water samples were collected during the wet season at two sites in the Reservoir. Paralytic shellfish toxins (PSTs) were detected in both samples (sites 1 and 2); however, the levels of PSTs were higher in site 1. Gonyautoxin 2 was the major cyanotoxin found in the Reservoir. Both samples were able to induce cytotoxic effects (reduced Mitotic Index) and damage the genetic material (i.e., increased frequencies of chromosome aberration and micronuclei) of meristematic cells of A. cepa. The cellular and genetic damages were higher in the sample site 1, wherein high levels of PSTs were verified. Thus, our findings suggested that cyanotoxins-contaminated waters may damage the genetic material of living organisms, and therefore this group of contaminants should be assessed for their potential genotoxicity

Biomarkers responses in fish (Atherinella brasiliensis) of paranaguá bay, southern Brazil, for assessment of pollutant effects

Paranaguá bay is a complex estuary located in southern Brazil containing three protected areas listed by UNESCO. Historically, the estuary has been affected by urban, industrial, agricultural and harbor activities, and occasional accidents. Specifically, the explosion of the Chilean ship Vicuña in December 2004 spilled methanol and crude and fuel oils which affected both protected and non-protected areas. The present study sought to investigate the pollution threat to aquatic organisms in order to evaluate the potential effects of pollutants. One hundred and twenty adult fish Atherinella brasiliensis were collected from different sites within Paranaguá estuary, including the harbor and open ocean, during summer, autumn and winter of 2005. Among the biomarkers, the somatic index, chemical analysis of bile, biochemical, genetic and morphological parameters were considered. Chemical analysis of bile showed a continuous bioavailability of polycyclic aromatic hydrocarbons (PAHs) according to proximity to the harbor site. The histopathological findings have demonstrated aconsiderable incidence of severe pathologies in the liver and gills, corroborated by biochemical disturbances and genetic damage. These findings indicate that more studies are necessary to evaluate both water quality and fish health so as to permit a better analysis of the impact of pollution in Paranaguá estuary.A Baia de Paranaguá é um complexo estuarino localizado no sul do Brasil constituído de três áreas de proteção ambiental listadas pela UNESCO. Historicamente, o estuário tem sido afetado por atividade urbana, industrial, agricultura e portuária, e eventualmente por acidentes. Particularmente a explosão do navio Chileno Vicuña em dezembro de 2004 derramou metanol, óleo cru e combustível atingindo áreas protegidas e não protegidas. O presente estudo tem por objetivo investigar a poluição em organismos aquáticos. Cento e vinte indivíduos adultos do peixe Atherinella brasiliensis foram coletados em quatro diferentes pontos de coleta no estuário de Paranaguá, partindo do porto até o oceano aberto nos períodos de verão, inverno e primavera de 2005. Os índices somáticos, parâmetros químicos, enzimáticos, genéticos e morfológicos foram considerados. As análises histopatológicas demonstraram expressiva incidência de patologia no fígado e nas brânquias algumas vezes corroboradas pelas alterações bioquímicas. Danos genéticos e anormalidades genéticas também foram observados. As análises químicas na bile mostraram uma contínua biodisponibilidade de hidrocarbonetos policíclicos aromáticos para os organismos aquáticos. Os dados obtidos indicam que a qualidade da água e a saúde dos peixes encontram-se bastante comprometidos no estuário de Paranaguá

Genome Size Evaluation in Tetraodontiform Fishes from the Neotropical Region

Abstract Smooth pufferfish of the family Tetraodontidae had become pure genomic models because of the remarkable compaction of their genome. This trait seems to be the result of DNA loss following its divergence from the sister family Diodontidae, which possess larger genomes. In this study, flow cytometry was used for estimate the genome size of four pufferfish species from the Neotropical region. Cytogenetic data and confocal microscopy were also used attempting to confirm relationships between DNA content and cytological parameters. The haploid genome size was 0.71±0.03 pg for Sphoeroides greeleyi, 0.34±0.01 pg for Sphoeroides spengleri, 0.82± 0.03 pg for Sphoeroides testudineus (all Tetraodontidae), and 1.00±0.03 pg for Chilomycterus spinosus (Diodontidae). These differences are not related with ploidy level, because 46 chromosomes are considered basal for both families. The value for S. spengleri represents the smallest vertebrate genome reported to date. Since erythrocyte cell and nuclear sizes are strongly correlated with genome size, the variation in this last is considered under both adaptive and evolutionary perspectives