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Manduca sexta Cellular/Molecular Investigations

A major goal of college science courses is teaching students to do science--including generating hypotheses, designing experiments, collecting and interpreting data, performing statistical analyses, integrating data sets, interpreting the research literature, and writing formal laboratory reports. Attaining these goals in the cellular/molecular curriculum at the introductory level can be a particular challenge. The students' limited experience with sophisticated and abstract concepts, compounded by their limited exposure to contemporary techniques and equipment, make it difficult to give introductory students wide ranging freedom in the laboratory.

One response to this situation is to investigate a relatively familiar but not readily predictable phenomenon. A key here is that the lab series is a guided investigation in which the faculty sets the boundaries narrowly. A question(s) is posed and the techniques are selected by the teacher. The outcome of the experiment however is not immediately obvious. While not truly an open-ended, investigative experience, students must exercise their creativity, problem solving, and critical thinking skills in order to formulate a hypothesis, design the appropriate controls, and interpret the data. This approach also has the advantages of ensuring some measure of student success and building technical skills for future laboratory work.

Manduca sexta offers a particularly rich opportunity for doing cellular/molecular laboratories at the introductory undergraduate level using this guided-investigation approach. The hemolymph is easy to obtain and can be analyzed by a variety of basic techniques (e.g. protein concentration determination, protein activity assays, SDS-PAGE). A variety of treatments can be imposed on the insect and the effects can be measured as changes in the hemolymph. One such set of experiments might examine the response of Manduca sexta larvae to a bacterial infection. Another approach might be to examine hemolymph at various developmental stages.

Explore the possibilities of using M. sexta for cellular/molecular labs:



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March 1999