Lenira Maria Nunes Sepel

Isolation and visualization of nucleic acid with homemade apparatus: Practical activities for secondary schools

In many developing countries one of the major problems in the teaching science is the lack of adequate equipment and reagents. One way to solve the problem of the absence of laboratory equipment is to develop practical classes in which students construct some of the equipment needed for the students to understand abstract topics in molecular biology. In this article we describe how students can be motivated to construct a microcentrifuge and electrophoresis apparatus with simple materials. We also give details of two practical activities (nucleic acid extraction and the separation of DNA and RNA by agarose gel electrophoresis) that use common non‐hazardous household substances and only a few laboratory reagents. Some questions for the students to answer after the practical activities are also presented.

A low-cost apparatus for transforming Drosophila and detecting green fluorescent protein (GFP) genetic markers

We describe the transformation of white mutant Drosophila simulans with a piggyBac transposon vector and a green fluorescent marker (GFP) and show how to construct inexpensive micro-manipulation and epifluorescence equipment for use in transposon-mediated germ-line transformation. Although the number of G0 adult flies (16) obtained in relation to the number of injected eggs was very low (12.5%) it was comparable to the proportion described by other authors and can be considered as a good rate of transformation.

Evolutionary history of the Tip100 transposon in the genus Ipomoea

Tip100 is an Ac-like transposable element that belongs to the hAT superfamily. First discovered in Ipomoea purpurea (common morning glory), it was classified as an autonomous element capable of movement within the genome. As Tip100 data were already available in databases, the sequences of related elements in ten additional species of Ipomoea and five commercial varieties were isolated and analyzed. Evolutionary analysis based on sequence diversity in nuclear ribosomal Internal Transcribed Spacers (ITS), was also applied to compare the evolution of these elements with that of Tip100 in the Ipomoea genus. Tip100 sequences were found in I. purpurea, I. nil, I. indica and I. alba, all of which showed high levels of similarity. The results of phylogenetic analysis of transposon sequences were congruent with the phylogenetic topology obtained for ITS sequences, thereby demonstrating that Tip100 is restricted to a particular group of species within Ipomoea. We hypothesize that Tip100 was probably acquired from a common ancestor and has been transmitted vertically within this genus.

Reciclagem de agarose em laboratórios de biologia molecular

In molecular biology laboratories, the agarose gel electrophoresis is used on a daily basis in order to separate nucleic acid molecules. The agarose is a polimere of elevated cost. The goal of the present work consisted in the optimization of a protocole of agarose recycling, transforming it, once again, into a powdery material similar to the original, after performing the decontamination of Ethidium bromide, allowing its reuse in analitycal electrophoresis. The process, originally proposed by PALACIOS et al. (2000) receveid modifications and consisted in balancing the agarose in water, drying and milling it. The recycled agarose resembled the original, presenting slightly bigger and darker granules. The recycled agarose was avaliable for imediate use, being storegeable at room temperature, for wide periods of time and taking up very few space. It is fit for the manufacturing of analytical gels of the widest brand of concentrations and buffer compositions. Besides, recycling also contributes to the diminution of solid waste disposed in the enviroment and results in significant reduction of costs. The manufaturing of gels took place in a similar way as with the original product, not recquiring any aditional procedure. The recycled gels showed similar performance in electrophoresis and allowed and adequate resolution of bands.

Retracing and Rewriting Hooke's "Micrographia" Book for Teaching History of Science.

Abstract The history of science is an important component to acquire for achieving scientific literacy. In this study, a collaborative activity was applied in which the students were presented with the historical context in which Robert Hooke lived and developed the first register of the microscopic world. Furthermore, the students explored the environment using a microscope made by themselves, employing PET bottles and lenses obtained from CD or DVD readers and, finally, they drew and described selected objects, and collaboratively rewrote a ‘new version’ of Hooke’s classical book ‘Micrographia’. The study was performed in a secondary school, with 12- to 15-year-old students, and the hypothesis was that the planned intervention could enlarge students’ perception of historical aspects of the scientific discovery of the microscopic world, to a greater extent than traditional classes involving lectures and textbooks. The comparison was evaluated using a quantitative tool, called the History-Word-Association test (HWAT), which aims to evaluate the general vision of students regarding the agents, historical period and sociocultural circumstance involved in the issue addressed. The students that participated in the planned didactic activity showed a significant improvement in identification and retention of ideas associated with the history of the discovery of the microscopic world.

ORGANIZAÇÃO INICIAL DE UMA ILHA INTERDISCIPLINAR DE RACIONALIDADE A PARTIR DE UM TEMA ESPECÍFICO DA BIOLOGIA

Os virus fazem parte dos conteudos abordados nas aulas de biologia do ensino medio. Mas sera que assuntos interessantes relacionados aos virus nao deixam de ser trabalhados por nao serem considerados tao biologicos? Em vista disso, este trabalho investigou quais as potencialidades interdisciplinares desse tema para a sala de aula. Tomamos como referenciais de nossa pesquisa os conceitos de Abordagem Relacional e de Ilhas Interdisciplinares de Racionalidade. Apresentamos algumas reflexoes e possibilidades de trabalho interdisciplinar da tematica ‘virus’ para o Ensino Medio. Constatamos que existem diversas possibilidades de atividades para as quatro areas do conhecimento: Linguagens, Ciencias da Natureza, Matematica e Ciencias Humanas. A partir dessa abordagem inicial pretendemos implementar uma Ilha de Racionalidade sobre os virus com alunos e professores do Ensino medio, onde abordaremos questoes interdisciplinares desse tema. Esperamos assim, contribuir para um ensino um pouco menos fragmentado, despertando o interesse e participacao dos alunos no processo de aprendizagem.

Teaching Cell Biology in Primary Schools

Basic concepts of cell biology are essential for scientific literacy. However, because many aspects of cell theory and cell functioning are quite abstract, students experience difficulties understanding them. In this study, we investigated whether diverse teaching resources such as the use of replicas of Leeuwenhoek’s microscope, visualization of cells using an optical microscope, construction of three-dimensional cell models, and reading of a comic book about cells could mitigate the difficulties encountered when teaching cell biology to 8th-grade primary school students. The results suggest that these didactic activities improve students’ ability to learn concrete concepts about cell biology, such as the composition of living beings, growth, and cicatrization. Also, the development of skills was observed, as, for example, the notion of cell size. However, no significant improvements were observed in students’ ability to learn about abstract topics, such as the structures of subcellular organelles and their functions. These results suggest that many students in this age have not yet concluded Piaget’s concrete operational stage, indicating that the concepts required for the significant learning of abstract subjects need to be explored more thoroughly in the process of designing programs that introduce primary school students to cell biology.