El curriculum oculto y su pertinencia en la educación vocacional

O presente artigo apresenta uma discussão aceca do Currículo Oculto cujo objetivo foi compreender a contribuição deste tema para a docência na Educação Profissional. O currículo pode ser compreendido como uma forma de produção, organização e registro dos saberes escolares, portanto necessita estar articulado a uma prática reflexiva e considerar que nele interagem relações culturais e sociais dentro do ambiente educacional. Existe também, dentro do contexto escolar, atitudes e valores transmitidos subliminarmente pelas relações sociais e pelas rotinas do cotidiano, que não aparecem implícitas no currículo formal e contribui na formação do ser escolar, isso tudo se denomina currículo oculto. O estudo foi realizado dentro de uma abordagem qualitativa e contemplou uma pesquisa bibliográfica, de cunho descritivo e uma observação não participante. Foi possível identificar diversos elementos que embora não explicitados no currículo oficial, fazem parte dos processos e espaços escolares e contribuem para a formação profissional dos alunos.This article presents a discussion about the Hidden Curriculum whose objective was to understand the contribution of this theme to the teaching in Professional Education. The curriculum can be understood as a form of production, organization and registration of school knowledge, so it needs to be linked to a reflective practice and consider that cultural and social relations interact within it within the educational environment. There are also, within the school context, attitudes and values subliminally transmitted by social relations and daily routines, which do not appear implicit in the formal curriculum and contribute to the formation of the school being, this is called the hidden curriculum. The study was conducted within a qualitative approach and included a bibliographic research, descriptive and non-participant observation. It was possible to identify several elements that, although not explained in the official curriculum, are part of the school processes and spaces and contribute to the students' professional formation.Este artículo presenta una acalorada discusión sobre el Currículum Oculto cuyo objetivo era comprender la contribución de este tema a la enseñanza en la Educación Profesional. El plan de estudios puede entenderse como una forma de producción, organización y registro del conocimiento escolar, por lo que debe estar vinculado a una práctica reflexiva y considerar que las relaciones culturales y sociales interactúan dentro del entorno educativo. También existen, dentro del contexto escolar, actitudes y valores subliminalmente transmitidos por las relaciones sociales y las rutinas diarias, que no aparecen implícitas en el plan de estudios formal y contribuyen a la formación del ser escolar, esto se llama el plan de estudios oculto. El estudio se realizó dentro de un enfoque cualitativo e incluyó una investigación bibliográfica, observación descriptiva y no participante. Fue posible identificar varios elementos que, aunque no se explican en el plan de estudios oficial, forman parte de los procesos y espacios escolares y contribuyen a la formación profesional de los estudiantes

A toxicidade do Arsênio em organismos aquáticos

Dissertação (mestrado)-Universidade Federal do Rio Grande, Programa De Pós-Graduação em Ciências Fisiológicas – Fisiologia Animal Comparada, Instituto de Ciências Biológicas, 2006.O arsênio (As), um metalóide abundantemente distribuído na natureza, é um poluente despejado no ambiente aquático principalmente por processos agrícolas e industriais, podendo ocorrer em formas químicas diferentes. Os principais efeitos tóxicos do As são: inibição da respiração mitocondrial, competição com o fosfato durante a fosforilação oxidativa, inibição de enzimas de reparo de DNA, diminuição nas defesas antioxidantes, diminuição na atividade de algumas enzimas mitocondriais. O As pode acarretar um aumento na geração de espécies reativas de oxigênio (ROS), levando a uma situação de estresse oxidativo, que inclui o aumento na oxidação de proteínas. Dentre as defesas antioxidantes não enzimáticas pode-se destacar a glutationa reduzida (GSH), um tripeptídeo composto por glutamato, cisteína e glicina. A enzima glutamato cisteína ligase (GCL) é o passo limitante para a síntese da GSH. A GSH é conhecida por ser um dos mais importantes antioxidantes celulares e está diretamente ligada ao metabolismo do As no organismo para que este possa ser metilado. Hoje, esta reação também é considerada importante no processo de ativação da toxicidade do As, visto que metabólitos orgânicos intermediários que possuem As na sua forma trivalente [As(III)] são mais citotóxicos e mais genotóxicos que o As na sua forma inorgânica, que eram originalmente consideradas as formas químicas mais tóxicas. Dentre as defesas antioxidantes enzimáticas podemos destacar a catalase (CAT), superóxido dismutase (SOD) e a glutationa-S-transferase (GST), que desempenham um importante papel no processo de detoxificação de poluentes. Também podemos mencionar a importância da glutationa redutase (GR), uma enzima que catalisa a redução da glutationa a partir da glutationa oxidada que tem importante função no restabelecimento nos níveis de GSH. O objetivo geral deste trabalho é avaliar as respostas toxicológicas em organismos aquáticos após exposição ao arsênio. Estão presentes nesta dissertação dois trabalhos experimentais, no 1° trabalho foi avaliado as respostas antioxidantes mediadas pela GSH no peixe Danio rerio (Cypridinae) após exposição ao arsênio. Os peixes foram expostos a três concentrações incluindo a máxima permitida pela atual legislação brasileira (10 μg de As/L) durante 2 dias. Neste mesmo trabalho foram avaliados os níveis de GSH, a atividade das enzimas: GCL, GR, GST e CAT. Também foram avaliados os níveis de peroxidação lipídica, a produção de ROS e o consumo de oxigênio. Foram determinadas as espécies químicas de As presentes na água e nas brânquias do D. rerio expostos a este metalóide. Os resultados mostraram que a exposição ao arsênio pode afetar as respostas antioxidantes, uma vez que houve um aumento nos níveis de GSH concomitante com um aumento na atividade da GCL na concentração de 10 e 100 μg de As/L. Não foram observadas alterações na atividade das enzimas GR, GST e CAT. Foi detectada uma diminuição do consumo de oxigênio na maior concentração (100μg de As/L). Não foram observados danos lipídicos nem alterações na produção de ROS. A especiação química da água e do tecido mostrou que o arsênio inorgânico foi a forma química predominante em ambos. No 2° trabalho foi avaliado as respostas toxicológicas no poliqueto Laeonereis acuta (Nereididae) após exposição ao arsênio. Os poliquetos foram expostos a duas concentrações incluindo a máxima permitida pela legislação brasileira anterior (50 μg de As/L), durante 2 e 7 dias. Os resultados mostraram que houve um aumento no conteúdo de peroxidação lipídica nos animais expostos durante 2 dias a 50 μg de As/L. Paralelo a este resultado foi observado um aumento da atividade da SOD e uma diminuição na atividade da CAT. Também foi detectada uma diminuição da atividade da GST após 7 dias de exposição a 500 μg de As/L. Não foi detectado nenhum dano em nível de DNA, porém houve um aumento da peroxidação lipídica. A especiação química no tecido do L. acuta mostrou que a forma de arsênio predominante foi arsenobetaína (AsB), porém uma quantidade significativa de dimetilarsenato (DMA) e formas inorgânicas também foram detectadas, mostrando que o animal embora possua uma boa capacidade de metabolização não foi capaz de biotransformar completamente todo arsênio presente. Em ambos trabalhos as concentrações consideradas seguras pela atual e pela legislação brasileira anterior mostraram ser suficientes para induzir no caso do D rerio, uma resposta antioxidante e no caso do L. acuta, uma situação de estresse oxidativo em termos de peroxidação lipídica. A importância do presente trabalho reside no fato que até agora poucas pesquisas estudaram as respostas bioquímicas após exposição ao As em espécies aquáticas. Uma avaliação dos efeitos do As neste nível de organização poderá também fornecer informações a respeito dos níveis de segurança estabelecidos hoje pela legislação brasileira

Arsenic toxicity in mammals and aquatic animals: A comparative biochemical approach

Arsenic(As)is a wide spread pollutant in the world and its toxicity is related to its chemical form,with inorganic forms being considered more toxic than the organic form, and huge differences ineffects and processes ofmetabolism.This paper reviews the potential biochemical mechanisms of up take o farsenic by aquaporins,capacity for metabolism and cellular efflux of As. It is known that As can affect signaling pathways since it can activate proteins such as ERK2, p38 and JNK,as shown in mammals.Acomparison between phosphorylation sites of these proteins is presented in order to determine whether the same effect triggered by As in mammals might be observed in aquatic animals.The toxicity resulting from As exposure is considered to be linked to an imbalance between pro-oxidant and antioxidant homeostasis that results in oxidative stress.So,present review analyzes examples of oxidative stress generation by arsenic.Biotransformation of As is a process where firstly the arsenate is converted into arsenite and then transformed into mono-,di-, and trimethylated products. In the methylation process,the role of the omega isoform of glutathione-S-transferase(GST)is discussed. In addition, a phylogenetic tree was constructed for aquaporin proteins of different species, including aquatica nimals,taking into account their importance in trivalent arsenic uptak

Acetylcholinesterase activity and antioxidant capacity of zebrafish brain is altered by heavy metal exposure

Pollution is a world problem with immeasurable consequences. Heavy metal compounds are frequently found as components of anthropogenic pollution. Here we evaluated the effects of the treatment with cadmium acetate, lead acetate, mercury chloride, and zinc chloride in acetylcholinesterase activity and gene expression pattern, as well as the effects of these treatments in antioxidant competence in the brain of an aquatic and well-established organism for toxicological analysis, zebrafish (Danio rerio,Cyprinidae). Mercury chloride and lead acetate promoted a significant decrease in acetylcholinesterase activitywhereas they did not alter the gene expression pattern. In addition, the antioxidant competence was decreased after exposure to mercury chloride. The data presented here allowed us to hypothesize a signal transmission impairment, through alterations in cholinergic transmission, and also in the antioxidant competence of zebrafish brain tissue as some of the several effects elicited by these pollutants

Antioxidant responses in the nereidid Laeonereis acuta (Annelida, Polychaeta) after cadmium exposure

The objective of this study was to evaluate the effects of the exposure to cadmium on the antioxidant responses in the polychaeta Laeonereis acuta. The worms were submitted to 0, 5, and 100 mg of Cd/L during a period of test of 7 days. Cadmium was significantly (po0.05) accumulated in L. acuta in both concentrations assayed, but the concentration of reactive oxygen and nitrogen species (RONS)increased (po0.05) only in the group submitted to the highest concentration of cadmium (100 mg/L). At this concentration, a decrease in the activity of the superoxide dismutase and an increase of glutathione-S-transferase activity (po0.05) was observed. The levels of both lipid peroxides and the activities of catalase and glutathione peroxidase were not affected (p40.05) by the exposition to cadmium. Thus,cadmium can augment RONS levels and can interfere with the antioxidant defense system of the polychaete L. acuta, although cadmium does not directly induce oxidative stress unlike copper and iron

Evaluation of coexposure to inorganic arsenic and titanium dioxide nanoparticles in the marine shrimp Litopenaeus vannamei

The acute toxicity of titanium dioxide nanoparticles (nTiO2) that occur concomitantly in the aquatic environment with other contaminants such as arsenic (As) is little known in crustaceans. The objective of the present study is to evaluate whether coexposure to nTiO2 can influence the accumulation, metabolism, and oxidative stress parameters induced by arsenic exposure in the gills and hepatopancreas of the shrimp Litopenaeus vannamei. Organisms were exposed by dissolving chemicals in seawater (salinity = 30) at nominal concentrations of 10 μg/L nTiO2 or AsIII, dosed alone and in combination. Results showed that there was not a significant accumulation of As in either tissue type, but the coexposure altered the pattern of the metabolism. In the hepatopancreas, no changes were observed in the biochemical response, while in the gills, an increase in the glutamate-cysteine-ligase (GCL) activity was observed upon exposure to As or nTiO2 alone, an increase in the reduced glutathione (GSH) levels was observed upon exposure to As alone, and an increase in the total antioxidant capacity was observed upon exposure to nTiO2 or nTiO2 + As. However, these modulations were not sufficient enough to prevent the lipid damage induced by nTiO2 exposure. Our results suggest that coexposure to nTiO2 and As does not alter the toxicity of this metalloid in the gills and hepatopancreas of L. vannamei but does alter its metabolism, favoring its accumulation of organic As species considered moderately toxic

The role of lipoic acid in the protection against of metallic pollutant effects in the shrimp Litopenaeus vannamei (Crustacea, Decapoda)

The effects of cadmium (Cd) and arsenic (As), dosed alone or in combination have been poorly investigated in crustaceans. Besides, it is not known if dietary supplementation of exogenous antioxidants, like lipoic acid (LA), might prevent or even reverse toxic effects of Cd and As. The objective of the present study was to evaluate the role of lipoic acid in modulating biochemical responses after Cd and As exposures in Litopenaeus vannamei. Muscle from shrimp exposed to Cd alone or Cd + As showed a decrease in glutathione (GSH) levels, while the pre-treatment with LA reversed this situation. In this tissue, the pre-treatment with LA also induced an increase in glutathione-S-transferase (GST) activity in all groups. In hepatopancreas it was observed a marked accumulation of Cd and As, a decrease in the reactive oxygen species (ROS) concentration in response to Cd exposure alone (−LA); concomitant in the same group it was observed an increment of metallothionein-like content. As exposure induced an increase in GSH levels but LA reversed this increase. Also, LA showed to increase the GST activity in all groups treated. Besides, in this organ LA showed to augment total antioxidant competence. Obtained results indicate that LA can be used as a chemo-protectant against oxidative insults in shrimp

The effect of diet enriched with lipoic acid in the accumulation and metabolization of metals in different organs of Litopenaeus vannamei

The bioaccumulation of metals is a problem for shrimp farming due to toxicity. As the water used in the culture tanks comes from environment, the shrimps can be exposed directly accumulating these metals, suffering the toxic effect and being a source of exposure for humans. So, alternatives that can minimize/avoid both accumulation and promote metabolism of metals are welcome. In this study, the Litopenaeus vannamei received the antioxidant lipoic acid (LA) through diet for 4 weeks and posteriorly were exposed to cadmium (Cd) and arsenic (As) alone or in combination (nominal concentration of 1 mg/L) during 48 hr. A control group also was run in parallel (without LA and then submitted to both metals exposure). The accumulation of Cd and As and the capacity of As metabolization were analysed in gills, hepatopancreas and muscle of shrimp Litopenaeus vannamei. Our results showed that the LA administered through diet decrease the accumulation of both metals in gills and muscle and improved the metabolization of As, favouring the accumulation of non‐toxic compounds as arsenobetaine (AsB) in all organs analysed. Therefore, a diet enriched with LA is a good form of chemoprevention in aquaculture that improved the resistance of shrimps against metal contamination

Fullerene and omega-3 and omega-6 fatty acids on fish brain antioxidant status

The carbon nanomaterial fullerene (C-60) can act as anti or pro-oxidant. The aim of this study was to evaluate, in cell suspensions of carp brains (Cyprinus carpio, Cyprinidae), the effect of C-60 after a pre-treatment with polyunsaturated fatty acid (PUFAs) such as omega-3 (docosahexaenoic acid, DHA) and omega-6 (linoleic acid, LA). Assays consisted of a pre-treatment with PUFA (48 h) and then exposure to C-60 (2 h). Cell viability and total anti-oxidant capacity did not differ (p > 0.05). A reduction (p < 0.05) was observed in reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS) concentration in fish brain cells pre-exposed with PUFA groups and then exposed or not with C-60. An antioxidant effect of C-60 was evident since in control group (cells not pre-exposed to PUFA), a significant (p < 0.05) reduction of intracellular ROS concentration was observed, although this reduction was not enough to reduce the TBARS levels. Cysteine levels presented a reduction (p < 0.05) in all groups exposed to C-60. For glutathione (GSH), an increase (p < 0.05) was registered in cells exposed to C-60 without PUFAs pre-treatment and in the C-60 group pre-treated with DHA. Overall C-60 appears to play an antioxidant role that is modulated by PUFA, taking into account its effects on intracellular ROS concentration and MDA levels. Results also suggest that C-60 influences GSH synthesis, as showed for the augmented levels of this antioxidant and also for the lowering of the intracellular cysteine concentration.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Antioxidant responses in different body regions of the polychaeta Laeonereis acuta (Nereididae) exposed to copper

Antioxidant enzymes, total antioxidant capacity (TOSC) and concentration of reactive oxygen species (ROS) were measured in anterior (A), middle (M) and posterior (P) body regions of Laeonereis acuta after copper (Cu; 62.5 mg/l) exposure. A catalase (CAT) activity gradient observed in control group (lowest in A, highest in P) was not observed in Cu exposed group. Glutathione-S-transferase (GST) activity in A region of Cu group was higher than in A region of the control group. DNA damage (comet assay) was augmented in the A region of Cu group. Since copper accumulation was similar in the different body regions, sensitivity to copper in A regions seems to be related to lowest CAT activity. In sum, copper exposure lowered TOSC, a result that at least in part can be related to lowering of antioxidant enzymes like CAT. DNA damage was induced in the anterior region, where a lower CAT activity was observed