Moacelio Veranio Silva Filho

Cholinesterase activity of muscle tissue from freshwater fishes: Characterization and sensitivity analysis to the organophosphate methyl‐paraoxon

The biochemical characterization of cholinesterases (ChE) from different teleost species has been a critical step in ensuring the proper use of ChE activity levels as biomarkers in environmental monitoring programs. In the present study, ChE from Oreochromis niloticus, Piaractus mesopotamicus, Leporinus macrocephalus, and Prochilodus lineatus was biochemically characterized by specific substrates and inhibitors. Moreover, muscle tissue ChE sensitivity to the organophosphate pesticide methyl-paraoxon was evaluated by determining the inhibition kinetic constants for its progressive irreversible inhibition by methyl-paraoxon as well as the 50% inhibitory concentration (IC50) for 30 min for each species. The present results indicate that acetylcholinesterase (AChE) must be present in the muscle from P. mesopotamicus, L. macrocephalus, and P. lineatus and that O. niloticus possesses an atypical cholinesterase or AChE and butyrylcholinesterase (BChE). Furthermore, there is a large difference regarding the sensitivity of these enzymes to methyl-paraoxon. The determined IC50 values for 30 min were 70 nM (O. niloticus), 258 nM (P. lineatus), 319 nM (L. macrocephalus), and 1578 nM (P. mesopotamicus). The results of the present study also indicate that the use of efficient methods for extracting these enzymes, their kinetic characterization, and determination of sensitivity differences between AChE and BChE to organophosphate compounds are essential for the determination of accurate ChE activity levels for environmental monitoring programs.

Aprendizagem Baseada em Casos Investigativos e a Formação de Professores: O Potencial de Uma Aula Prática de Volumetria para Promover o Ensino Interdisciplinar

Investigative Case-Based Learning and Teacher Education: the Use of Volumetry to Promote Interdisciplinary Teaching. The Ministry of Education is employing efforts to restructure the curricula of high school in Brazil, including the Innovative Education Program in High School, which seeks to implement interdisciplinary activities in schools. This paper presents the conceptions of teachers in the area of Natural Sciences of High School of the State of Rio de Janeiro on the potential of a practice of Volumetry, used to determine the acidity of soft drinks and inserted in the application of Problem-Based Learning, to promote interdisciplinary teaching. Our results indicate that the activities developed are able to integrate knowledge from all disciplines that make up the curriculum of high school.

Toxinas de cianobactérias e microalgas marinhas: um desafio para a ecotoxicologia aquática

The purpose of this review is to draw attention to the growing number of secondary metabolites produced by microorganisms in aquatic environments, specially cyanobacteria and marine microalgae. The first group is a producer of major hepatotoxins, neurotoxins and dermatotoxins. Cyanobacteria are responsible for most poisoning events in epicontinental aquatic environments. Eukaryotic microalgae, in marine environments such as diatoms and dinoflagellates, are great producers of a variety of phycotoxins. These syndromes are caused by consumption of contaminated mussels or ciguatera intoxication by consumption of fish (CFP). The current situation demands attention because many events occur and are not notified for important historical studies on seasonal flower blooms. Methodological issues and skilled labor also hinder more precise diagnosis of the blooms. The cooperation between different professionals with different backgrounds as taxonomists, chemists, biologists and environmental engineers is essential for ecotoxicological studies on the risk assessment of these blooms and suggest changes in environmental legislation.

Toxins of cyanobacteria and microalgae: a challenge for aquatic ecotoxicology

The purpose of this review is to draw attention to the growing number of secondary metabolites produced by microorganisms in aquatic environments, specially cyanobacteria and marine microalgae. The first group is a producer of major hepatotoxins, neurotoxins and dermatotoxins. Cyanobacteria are responsible for most Boletim do Observatorio Ambiental Alberto Ribeiro Lamego, Campos dos Goytacazes/RJ, v. 4 n. 1, p. 57-80, jan. / jun. 2010 58 Manildo Marciao de Oliveira et al. Boletim do Observatorio Ambiental Alberto Ribeiro Lamego, Campos dos Goytacazes/RJ, v. 4 n. 1, p. 57-80, jan. / jun. 2010 poisoning events in epicontinental aquatic environments. Eukaryotic microalgae, in marine environments such as diatoms and dinoflagellates, are great producers of a variety of phycotoxins. These syndromes are caused by consumption of contaminated mussels or ciguatera intoxication by consumption of fish (CFP). The current situation demands attention because many events occur and are not notified for important historical studies on seasonal flower blooms. Methodological issues and skilled labor also hinder more precise diagnosis of the blooms. The cooperation between different professionals with different backgrounds as taxonomists, chemists, biologists and environmental engineers is essential for ecotoxicological studies on the risk assessment of these blooms and suggest changes in environmental legislation.