Francisco Filipak Neto

Mercury and DDT exposure risk to fish-eating human populations in Amazon

In order to investigate the potential risk of mercury and DDTs exposure to fish-eating human populations in Samuel Reservoir, not affected directly by gold-mining activities, the axial muscle of Cichla monoculus was analyzed. Twenty-nine and thirty adults individuals were collected respectively on February (rainy season) and August (dry season) 2007. The specimens were sacrificed by spinal section before sex identification, body weight and total length determination. For total mercury, DDT and DDE quantifications and cholinesterase activity samples of the axial muscle were frozen at -20°C, and for histopathological studies gill and liver were fixed in ALFAC solution for 16 h. A value of 48.2% and 33% of the individuals, respectively from rainy and dry seasons, presented mercury concentrations higher than the maximum established for safe human consumption (0.5 μg g⁻¹) by World Health Organization. A positive correlation between body weight and Hg concentration was observed only in individuals from the rainy season, but no correlation was observed to DDT and DDE from both seasons. Differently from that observed to mercury, DDT levels presented a significant difference between both studied seasons, but no correlation was observed for both mercury and DDTs and sex. The levels of DDTs in muscle of C. monoculus are under the maximum established by FAO-Alimentarius CODEX and Swedish Food Regulation for human consumption. The histopathological and neurotoxic findings showed that the wild population of fish is affected by chronic exposure to mercury, meaning risk also to fish-eating populations. Finally, the results showed that C. monoculus is an important vehicle for human exposure to mercury and DDTs in Samuel Reservoir and that it is necessary a continuous biomonitoring of the levels of both pollutants in order to manage the risk of exposure to human populations.

Water quality assessment of the Tubarão River through chemical analysis and biomarkers in the Neotropical fish Geophagus brasiliensis

The Tubarão River rises in Santa Catarina, Brazil, and has been historically affected by coal mining activities around its springhead. To evaluate its water conditions, an investigation regarding a possible decontamination gradient associated with the increased river flow toward the estuary, as well as the influence of seasonality over this gradient was performed through a series of biomarkers (vitellogenin, comet assay, lipid peroxidation, protein carbonylation, gluthatione, gluthatione S-transferase, acetylcholinesterase, light microscopy in liver, and scanning electron microscopy in gills) and chemical analysis (polycyclic aromatic hydrocarbons (PAHs) in bile and metal analysis in sediment) in the cichlid Geophagus brasiliensis. Two collections (summer and winter) were made in four distinct sites along the river, while sediments were sampled between those seasons. As expected, the contamination linked exclusively to mining activities was not observed, possibly due to punctual inputs of contaminants. The decontamination gradient was not observed, although seasonality seemed to have a critical role in the responses of biomarkers and availability of contaminants. In the summer, the fish presented higher histopathological damages and lower concentrations of PAHs, while in the winter they showed both higher genetic damage and accumulation of PAHs. The Tubarão suffers impacts from diverse activities, representing health risks for wild and human populations.

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

A Baia de Paranagua e um complexo estuarino localizado no sul do Brasil constituido de tres areas de protecao ambiental listadas pela UNESCO. Historicamente, o estuario tem sido afetado por atividade urbana, industrial, agricultura e portuaria, e eventualmente por acidentes. Particularmente a explosao do navio Chileno Vicuna em dezembro de 2004 derramou metanol, oleo cru e combustivel atingindo areas protegidas e nao protegidas. O presente estudo tem por objetivo investigar a poluicao em organismos aquaticos. Cento e vinte individuos adultos do peixe Atherinella brasiliensis foram coletados em quatro diferentes pontos de coleta no estuario de Paranagua, partindo do porto ate o oceano aberto nos periodos de verao, inverno e primavera de 2005. Os indices somaticos, parâmetros quimicos, enzimaticos, geneticos e morfologicos foram considerados. As analises histopatologicas demonstraram expressiva incidencia de patologia no figado e nas brânquias algumas vezes corroboradas pelas alteracoes bioquimicas. Danos geneticos e anormalidades geneticas tambem foram observados. As analises quimicas na bile mostraram uma continua biodisponibilidade de hidrocarbonetos policiclicos aromaticos para os organismos aquaticos. Os dados obtidos indicam que a qualidade da agua e a saude dos peixes encontram-se bastante comprometidos no estuario de Paranagua.

Metabolic switches during the first steps of adipogenic stem cells differentiation.

The understanding of metabolism during cell proliferation and commitment provides a greater insight into the basic biology of cells, allowing future applications. Here we evaluated the energy and oxidative changes during the early adipogenic differentiation of human adipose tissue-derived stromal cells (hASCs). hASCs were maintained under differentiation conditions during 3 and 7days. Oxygen consumption, mitochondrial mass and membrane potential, reactive oxygen species (ROS) generation, superoxide dismutase (SOD) and catalase activities, non-protein thiols (NPT) concentration and lipid peroxidation were analyzed. We observed that 7days of adipogenic induction are required to stimulate cells to consume more oxygen and increase mitochondrial activity, indicating organelle maturation and a transition from glycolytic to oxidative energy metabolism. ROS production was only increased after 3days and may be involved in the differentiation commitment. ROS source was not only the mitochondria and we suggest that NOX proteins are related to ROS generation and therefore adipogenic commitment. ROS production did not change after 7days, but an increased activity of catalase and NPT concentration as well as a decreased lipid peroxidation were observed. Thus, a short period of differentiation induction is able to change the energetic and oxidative metabolic profile of hASCs and stimulate cytoprotection processes.

Mixtures of benzo(a)pyrene, dichlorodiphenyltrichloroethane and tributyltin are more toxic to neotropical fish Rhamdia quelen than isolated exposures

The effects of benzo(a)pyrene (BaP), dichlorodiphenyltrichloroethane (DDT) and tributyltin (TBT) association were investigated through a multi-biomarker approach. Ten Rhamdia quelen fish per group were exposed through intraperitoneal injections either to BaP (0.3; 3 or 30 mg kg(-1)), DDT or TBT (0.03; 0.3 or 3 mg kg(-1)) or BaP/DDT, BaP/TBT, DDT/TBT or BaP/DDT/TBT on their lowest doses. The experiments were divided in acute (one dose, 5-day) and sub-chronic (3 doses, 15-day). Control groups received an equal volume of PBS or canola oil (1 ml kg(-1)). The three tested contaminants altered AChE activity in brain and muscle in similar ways; the mixtures antagonized the increase evoked by the contaminants alone. BaP and TBT increased GSH content and mixtures reduced it. GPx activity was increased by DDT and TBT in the 15-day experiment and reduced by the mixtures. BaP increased GST activity in sub-chronic experiment while TBT reduced it in the acute experiment. BaP/TBT increased GST activity compared to all groups; the other mixtures reduced it compared to BaP or DDT in the 5-day experiment. BaP, DDT and TBT increased δ-ALAd activity mainly in acute exposure; the mixtures also increased δ-ALAd compared to DDT or TBT in 5 and 15-day. BaP, TBT and BaP/DDT decreased LPO in the acute experiment. In the sub-chronic experiment DDT/TBT increased LPO when compared to TBT. None of the contaminants alone altered PCO, but all mixtures increased it compared to one or another contaminant. Contaminants isolated had a more acute effect in ALT plasma level; their lowest dose, which had no effect alone, in combination has led to an increase of this enzyme, especially after 15 days. DDT increased AST in the acute and sub-chronic experiments, while TBT did the same in the latter. DDT/TBT decreased AST opposing the effect of the contaminants alone in the 5-day experiment. Hepatic lesions index could be explained by a more acute effect of the contaminants alone or combined and by activation of cell defenses after the sub-chronic exposure. TBT increased melanomacrophages counting in the 5-day experiment and the mixtures increased it in the 5 and 15-day experiments. Overall, the majority of the biomarkers pointed to a more toxic effect when these contaminants were combined, leading to unexpected toxicities compared to individual exposure scenarios. These findings are relevant considering environmental exposure conditions, since organisms are often exposed to different combinations of contaminants.

Toxicological interactions of silver nanoparticles and non-essential metals in human hepatocarcinoma cell line

Toxicological interaction represents a challenge to toxicology, particularly for novel contaminants. There are no data whether silver nanoparticles (AgNPs), present in a wide variety of products, can interact and modulate the toxicity of ubiquitous contaminants, such as nonessential metals. In the current study, we investigated the toxicological interactions of AgNP (size=1-2nm; zeta potential=-23mV), cadmium and mercury in human hepatoma HepG2 cells. The results indicated that the co-exposures led to toxicological interactions, with AgNP+Cd being more toxic than AgNP+Hg. Early (2-4h) increases of ROS (DCF assay) and mitochondrial O2- levels (Mitosox® assay) were observed in the cells co-exposed to AgNP+Cd/Hg, in comparison to control and individual contaminants, but the effect was partially reverted in AgNP+Hg at the end of 24h-exposure. In addition, decreases of mitochondrial metabolism (MTT), cell viability (neutral red uptake assay), cell proliferation (crystal violet assay) and ABC-transporters activity (rhodamine accumulation assay) were also more pronounced in the co-exposure groups. Foremost, co-exposure to AgNP and metals potentiated cell death (mainly by necrosis) and Hg2+ (but not Cd2+) intracellular levels (ICP-MS). Therefore, toxicological interactions seem to increase the toxicity of AgNP, cadmium and mercury.

Complex metabolic interactions between benzo(a)pyrene and tributyltin in presence of dichlorodiphenyltrichloroethane in South American catfish Rhamdia quelen

In an attempt to explore complex metabolic interactions between toxicants present in polluted freshwater, hepatic metabolism of benzo(a)pyrene (BaP) and tributyltin (TBT) in fish was investigated when these compounds were administrated alone, mixed together and along with dichlorodiphenyltrichloroethane (DDT). Ten Rhamdia quelen per group were treated with a single intra-peritoneal (IP) dose (5-day experiment) or three successive doses (15-day experiment) either containing BaP (0.3; 3 or 30mgkg(-1)) or TBT (0.03; 0.3 or 3mgkg(-1)) or a combination of BaP+TBT, BaP+DDT, TBT+DDT and BaP+TBT+DDT under their respective lower doses, with DDT dose kept at 0.03mgkg(-1). Tetrahydroxy-benzo(a)pyrene (BaP-tetrol-I), and dibutyltin (DBT) and monobutyltin (MBT) were analyzed to assess BaP and TBT hepatic metabolism, respectively. A significant difference in BaP-tetrol-I concentration was observed in liver and bile between the lowest and the highest doses of BaP in both 5 and 15-day experiments. In the 15-day experiment, the presence of TBT with BaP reduced the amount of BaP-tetrol-I in bile compared to the BaP alone. The time of exposure and the number of doses affected BaP-tetrol-I concentration in the bile of fish exposed to BaP 0.3mgkg(-1) and BaP+DDT. TBT and its metabolites concentrations showed a dose-dependent increase in the liver in both experiments and in the bile in the 5-day experiment. TBT at its lowest dose was completely metabolized into DBT and MBT in the liver in the 15-day experiment. No TBT metabolites were detected in the bile of fish exposed to the mixtures in the 5-day experiment, except for a small MBT amount found in BaP+TBT+DDT. This study strengthens the hypothesis of a metabolic interaction between BaP and TBT in fish and suggests DDT as an important third player when present in the mixture.

Toxicological interactions of silver nanoparticles and organochlorine pesticides in mouse peritoneal macrophages

Abstract Nanotechnology occupies a prominent space in economy and science due to the beneficial properties of nanomaterials. However, nanoparticles may pose risks to living organisms due to their adsorption and pro-oxidative properties. The aim of the current study was to investigate the effects of polymer-coated silver nanoparticles (AgNPs) and organochlorine pesticides (OCPs), as well as their combined effects on mouse peritoneal macrophages. Macrophages were isolated and exposed to three concentrations of AgNPs (groups: N1 = 30, N2 = 300 and N3 = 3000 ng.ml−1), two concentrations of OCPs (groups: P1 = 30 and P2 = 300 ng.ml−1) and the six possible combinations of these two contaminants for 24 h. AgNPs had irregular shape, Feret diameter of 8.7 ± 7.5 nm and zeta potential of −28.7 ± 3.9 mV in water and −10.7 ± 1.04 mV in culture medium. OCP mixtures and the lower concentrations of AgNPs had no detectable effects on cell parameters, but the highest AgNPs concentration showed high toxicity (trypan blue and MTT assays) resulting in morphological changes, increase of nitric oxide levels and phagocytic index. Foremost, the association of N3 and P2 led to distinct effects from those observed under single exposure.

Modulatory effect of nano TiO2 on Pb in Hoplias malabaricus trophically exposed

This study investigated the hepatic and neural effects of TiO₂ nanoparticle and Pb in Hoplias malabaricus trophically exposed. The alanine transaminase activity was altered at the high dose of exposed group to Pb and at the lowest doses of co-exposed groups. It may reflect the hepatic effects of TiO₂ on Pb toxicity, but the aspatate transaminase activity was not altered. The decreased injury index observed at the highest dose of co-exposed group compared to TiO₂ may be related to the increased energy demand and can explain the more pronounced toxic effects observed in this group. The liver authomethallography revealed the metals presence at high dose groups. Serotonin concentration increased at the Pb lowest dose and at the highest dose of co-exposed group compare to control. Most importantly, when associated the contaminants were able to interact and altered some biomarkers. However, further studies, about action mechanisms of this co-exposure are needed.

Responses of human hepatoma HepG2 cells to silver nanoparticles and polycyclic aromatic hydrocarbons

Abstract The nanotechnology has revolutionized the global market with silver nanoparticles (AgNP) occupying a prominent position due to their remarkable anti-bacterial properties. However, there is no data about the adverse and toxic effects of associations of AgNP and ubiquitous compounds, such as polycyclic aromatic hydrocarbons (PAH). In the current study, we investigated the responses of HepG2 cells to realistic concentrations of AgNP (0.09, 0.9, and 9 ng ml−1) and mixture of PAH (30 and 300 ng ml−1), separately and in association. Cell viability and cytotoxicity (neutral red retention and MTT production assays) and proliferation (crystal violet [CV] assay), xenobiotic efflux transporter activity (rhodamine B accumulation assay), ROS levels (dichlorodihydrofluorescein diacetate assay), and lipid peroxidation (pyrenylphosphine-1-diphenyl assay) were analyzed. There was no decreases of cell viability after exposure to AgNP, PAH and most of AgNP + PAH associations, but increases of cell viability/number (CV assay) occurred. Efflux transporter activity was not affected, with exception of one AgNP + PAH associations, ROS levels increased, but lipid peroxidation decreased. Some toxicological interactions occurred, particularly for the highest concentrations of AgNP and PAH, but there is no evidence that these interactions increased the toxicity of AgNP and PAH.