Myocyte enhancer factor 2 (MEF2) is in the MADS (MCM1-agamous-deficiens-serum response factor) family of transcription factors. Although MEF2 is known as a myogenic factor, the expression pattern of the MEF2 family of genes (MEF2A-D) in developing brain also suggests a role in neurogenesis. Here we show that transfection with MEF2C, the predominant form in mammalian cerebral cortex, induces a mixed neuronal͞myogenic phenotype in undifferentiated P19 precursor cells. During retinoic acidinduced neurogenesis of these cells, a dominant negative form of MEF2 enhances apoptosis but does not affect cell division. The mitogen-activated protein kinase p38␣ activates MEF2C. Dominant negative p38␣ also enhances apoptotic death of differentiating neurons, but these cells can be rescued from apoptosis by coexpression of constitutively active MEF2C. These findings suggest that the p38␣͞MEF2 pathway prevents cell death during neuronal differentiation.
In this study we measured the learning outcomes resulting from using molecular visualization software in lecture and in the teaching laboratory of a large introductory-level undergraduate biology majors' course. The study was initially carried out in the Fall semester of 1999; the results of this study were used to devise an expanded laboratory component that was evaluated in a second study carried out in the Fall of 2000. In both studies, students (n ؍ 175 and 161) attended two 50-min lectures that used molecular visualization software to explain protein structure and function and the gene-protein connection. Students also used this software during one 3-h laboratory session as a tool for exploring these topics. Students completed open-ended pre-and post-surveys that involved a related but unfamiliar task. Survey responses were scored for correctness, as well as by the type(s) of explanations used in the response. We found the following eight types of responses that students employed to explain protein structure and function: genetics, protein structure, chemical interactions, amino acid sequence, purpose/teleology, extrinsic factors, miscellaneous, and none. In both studies, the frequencies of correct answers, as well as the frequencies of each response type, showed significant changes as a result of lecture and/or lab. The effects of lecture were highly similar in both studies. The changes in the expanded lab resulted in significant changes in outcome. Overall, the curriculum effectively communicated several core concepts in protein biochemistry and expanded the conceptual "toolkit" that students applied to problems of protein structure and function. Lecture increased students' understanding of the role of amino acid sequence, whereas lab tended to increase their understanding of three-dimensional structure and the gene-protein connection. Our results demonstrate that exposure to molecular visualization, even for a relatively brief time, can improve students' understanding of protein structure and function. In addition, we demonstrate the differing and largely non-overlapping effects of lecture and lab, suggesting that effective use of molecular visualization should involve both types of activities.Keywords: Evaluation, molecular visualization, protein structure.Communicating an understanding of protein structurefunction relationships and the connection between gene and protein is a major component of virtually all biology courses at the high school and introductory college levels. A minimal understanding of these ideas includes the following core concepts.(1) Proteins are the major component of living cells and perform the vast majority of tasks required for life.(2) Most genes act by producing protein products with specific cellular functions.(3) The function of a protein is determined by its shape, as well as its potential for interaction with other molecules.(4) The shape of a protein, in turn, is determined by the sequence of amino acids that make up its chemical structure.(5) Genetic mutations often l...
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