Aline Sueli de Lima Rodrigues

Memory deficit in Swiss mice exposed to tannery effluent.

Although it is known that tannery effluents constitute highly toxic pollutants whose effects in humans represent public health problems in several countries, studies involving experimental mammalian models are rare. In this context, the objective of the present study was to assess the effect of the exposure to tannery effluent on the memory of male and female Swiss mice. Animals of each sex were distributed into two experimental groups: the control group, in which the animals received only drinking water and the effluent group, in which the mice received 1% of gross tannery effluent diluted in water. The animals were exposed to the effluent by gavage, oral dosing, for 15days, ensuring the administration of 0.1mL of liquid (water or effluent)/10g of body weight/day. On the 14th and 15th experimental days the animals were submitted to the object recognition test. It was observed that the new object recognition indices calculated for the animals exposed to the effluent (males and females) were significantly lower than those obtained with the control group. The exposure to tannery effluent caused memory deficit in Swiss mice in a similar way for both sexes, reinforcing previous findings that these pollutants affect the central nervous system. It contributes to the knowledge in the area by attesting harmful effects to the cognition of such animals.

Valores de background geoquímico e suas implicações em estudos ambientais

The establishment of background geochemical values as a relative measure to distinguish anthropogenic input from natural (geogenic and/or biogenic) concentrations of elements in different environmental samples, is one of the most important subjects in recent environmental sciences. The relationship between natural and anthropogenically altered concentrations of chemical species is a question that involves many implications in the geological, toxicological, biological and other areas of knowledge. This is especially important when geochemical interpretations of toxic elements are required. Thus, the principal objective of this article is to present and discuss the reasons for which the establishment of background geochemical values has implications in environmental studies. Throughout this article some concepts of the geochemical background used by various authors is presented and the main methods used for assessing background concentration of elements (direct and indirect methods). In addition, some examples of studies developed in Brazil are presented. Studies involving the establishment of background geochemical values are important because they allow the evaluation of potential contamination risks and the identification of natural trace-element concentrations in a determined area.

Dermal exposure to tannery effluent causes neurobehavioral changes in C57Bl/6J and Swiss mice.

Tannery effluents constitute highly polluting residues, which can cause negative impacts to peoples health and the environment. However, studies that have investigated the effects of the exposure to these xenobiotics on the central nervous system of mammal experimental models are rare, the few that have been published focusing on the exposure via oral intake (ingestion of water containing tannery effluent concentrations). In this sense, and with the objective of expanding the knowledge beyond the neurotoxic effects observed when water contaminated by these xenobiotics is ingested, the neurobehavioral effects of dermal exposure of male C57Bl/6J and Swiss mice were analyzed. The animals were exposed to raw (wet blue-type) tannery effluent for two hours during five days, totalizing 15 days of exposure. Afterwards, the animals underwent the elevated plus-maze (predictive of anxiety) and the object recognition tests (identification of memory deficit). Our data show that the dermal exposure to the tannery effluent caused an anxiogenic behavior in these animals, when compared those that did not have direct contact with these xenobiotics. It was also observed that the animals exposed to the tannery effluent obtained lower novel object recognition indices, thus evidencing memory deficit and indicating a possible influence of the tannery effluent constituents in animal cognition. The present study attests the hypothesis that dermal exposure to tannery effluents containing neurotoxic substances causes behavioral disorders in C57Bl/6J and Swiss mice.

Memory and depressive effect on male and female Swiss mice exposed to tannery effluent

Although tannery industries generate substantial profits to the countries they are located in, they work with one of the most environmentally harmful human activities. Tannery effluents (TE) are highly toxic; thus, their improper release into water bodies may cause severe problems to individuals depending on this water. Therefore, the aim of the current study is to assess the effects of oral exposure to TE on the anxiety-, memory deficit- and depression-predictive behaviors in male and female Swiss adult mice. The following experimental groups were set in order to do so, control, positive control (reference drugs) and effluent. The animals in the effluent group were treated with 5% TE diluted in potable water for 15 consecutive days. The neurobehavioral tests started on the 12th experimental day. The results found through the elevated plus-maze test (for anxiety prediction) showed no anxiogenic or anxiolytic effects on animals exposed to TE. On the other hand, animals treated with TE showed short- and long-term memory deficit in the object recognition test, as well as depression-predictive behavior in the forced swimming test. These results may concern the high concentration of heavy metals and neurotoxic organic compounds in the TE. Therefore, the oral exposure to TE, even for a short period-of-time, has effects on the central nervous system (CNS) that lead to neurobehavioral changes. Thus, the current study broadens the knowledge on this research field by demonstrating the neurotoxicity of xenobiotics to male and female Swiss mice.

Evaluation of the mineral exploration influence on sediment composition in the Gualaxo do Norte River Basin (MG-Brazil) based on geochemical and stratigraphic data

The aim of this study was to investigate the influence of mining on the geochemical composition of the alluvial sediments of the Gualaxo do Norte River Basin, located in the eastern-southeastern portion of the Quadrilátero Ferrífero (Minas Gerais State, Brazil). The analysis of the sedimentological succession was carried out using 16 stratigraphic sections (cutbanks and alluvial terraces) and analysis of 111 sediment samples for major- and trace-elements by ICP-OES. The stratigraphic analysis revealed the deposition history of the collected sediments. Anomalous concentrations of certain elements such as As and Pb were found, which are associated with stratigraphic facies with evidences of gold artisanal mining, and Fe anomalies associated with iron ore mining. The classification of the sections was possible by means of principal component analysis. From the sediment characteristics, three groups were identified: (1) those influenced by iron ore mining and gold artisanal mining; (2) those influenced by iron ore mining and (3) those with no influence of human activities.

Centenário do descobrimento da doença de Chagas: desafios e perspectivas

O presente trabalho faz referencia ao centenario do descobrimento da doenca de Chagas, comemorado em 2009. Este fato, considerado um marco importante da historia da medicina, ocorreu em 1909 quando Carlos Chagas, atraves de um relato minucioso, anunciou para a comunidade cientifica a deteccao, em humanos, do protozoario Trypanosoma cruzi , agente causador da doenca de Chagas. Atraves de uma breve discussao, o presente artigo aborda os principais desafios e as perspectivas relacionadas a situacao atual da doenca. Espera-se com este estudo, instigar trabalhos futuros, a fim de alcancar concretizacoes de progressos ainda nao superados.

BACKGROUND VALUES FOR CHEMICAL ELEMENTS IN SEDIMENTS OF THE GUALAXO DO NORTE RIVER BASIN, MG, BRAZIL

The aim of this study was to establish local background values for Fe, As, Pb, Mn, Ba, Zn and Ni using sediments from cutbanks and alluvial terraces of the Gualaxo do Norte River basin, Minas Gerais State, Brazil. A total of 16 stratigraphic sections were surveyed along the basin and 120 samples were analyzed. To establish background values we took into account mineralogical and grain-size analyses, faciologic interpretations, geochemical evaluations (by means of aqua regia partial digestion and ICP-OES readings), and the application of statistical techniques (boxplot representations, iterative 2σ technique, cumulative frequency curve and calculated distribution function). The results reveal relatively high background values for As, Pb, Mn, Ba, Zn and Ni (respectively 64.2; 43.8; 1636.0; 141.4; 65.3 and 39.0 mg.kg-1). The concentrations of these elements are possibly related to the local geology, being the concentrations higher than these values linked to mining activity in the study region, in special gold mining. On the other hand, the background values established for Fe is lower than the values identified in the majority of the sections analyzed. The background value established for Fe corresponds to a concentration of 8.2%. However, concentrations higher than 48% were identified in the study area. There is a strong evidence of Fe enrichment due to mining at the head of the basin. In conclusion, we can say that the proposed values are important parameters for local environmental/territorial management and may help alerting public managers of the necessity of remediation of certain sites, where anomalous toxic element concentrations are identified.

Vermicompostagem de lodo de curtume em associação com esterco bovino utilizando Eisenia fetida

Tannery industry-generated sludge is an example of residue that causes important environmental problems. In this sense, the objective of the present study was to evaluate vermicomposting of tannery sludge, as a method of treatment this waste. Due to the toxic characteristics of the tannery sludge, it was mixed with cattle dung in various proportions, on dry weight basis. During 105 days, biomass, number of individuals (Eisenia fetida ), pH, moisture and temperature of the experimental units were assessed. The substrates were chemically characterized at the beginning and at the end of the vermicomposting process. No significant differences were observed in pH in groups with lower concentrations of sludge, there was a significant decrease in pH of the groups with higher concentrations of the residue during vermicomposting. Mg, Fe, Mn and Zn contents were high in the vermicompost in all treatments. The C/N ratio was low in the substrate of all treatments, indicating the maturation of the final substrate. The results indicate that vermicomposting promotes the conversion of sludge to manure in a short time interval, thus constituting a biotechnological process of treatment able to add agronomic value to this residue.

Zinc oxide nanoparticles in predicted environmentally relevant concentrations leading to behavioral impairments in male swiss mice

Although the potential neurotoxic effects from the exposure to zinc oxide nanoparticles (ZnO NPs) on humans and on experimental models have been reported in previous studies, the effects from the exposure to environmentally relevant concentrations of them remain unclear. Thus, the aim of the present study is to investigate the effects from the exposure to environmentally relevant concentrations of ZnO NPs on the behavior of male Swiss mice. The animals were daily exposed to environmentally relevant concentrations of ZnO NPs (5.625×10-5mgkg-1) at toxic level (300mgkg-1) through intraperitoneal injection for five days; a control group was set for comparison purposes. Positive control groups (clonazepam and fluoxetine) and a baseline group were included in the experimental design to help analyzing the behavioral tests (open field, elevated plus maze and forced swim tests). Although we did not observe any behavioral change in the animals subjected to the elevated plus maze and forced swim tests, our data evidence the anxiogenic behavior of animals exposed to the two herein tested ZnO NPs concentrations in the open field test. The animals stayed in the central part of the apparatus and presented lower locomotion ratio in the central quadrants/total of locomotion during this test. It indicates that the anxiogenic behavior was induced by ZnO NP exposure, because it leads to Zn accumulation in the brain. Thus, the current study is the first to demonstrate that the predicted environmentally relevant ZnO NPs concentration induces behavioral changes in mammalian experimental models. Our results corroborate previous studies that have indicated the biological risks related to the water surface contamination by metal-based nanomaterials.

Análise das concepções e opiniões de discentes sobre o ensino da biologia

Analysis of concepts and opinions of students about Biology teaching This work presents and discusses the results of the study with 99 high-school students in a private school in the city of Ouro Preto-MG. Its main objectives were to identify their conceptions about Biology and their opinion about Biology teaching and to build a scenario of investigation for future, beginner or experienced teachers in the educational area. In order to overcome the speculative discourse, the school knowledge and the educational practices are questioned. This study obtained important information that may help the educational practice of teachers in Biology teaching.