Fitch, David IBN-9506844 To understand how morphological diversity in multicellular animals has arisen by the accumulation of evolutionary changes in genes, an understanding is first required of how morphology is specified by genes and developmental mechanisms. The 4-celled tail tip of the nematode, Caenorhabditis elegans, is being studied as a model for elucidating the genes and developmental processes involved in producing its morphology. Because this structure adopts different morphologies in related species, the tail tip provides a model for the evolution of morphogenesis as well. In C. elegans, the shape of the tail tip is pointy in adult hermaphrodites and blunt in adult males. The pointy shape in hermaphrodites results from retention of the larval state, whereas the blunt shape in males results from cell fusions and changes in cell size, shape and possible adhesion that occur rapidly, just before the last larval molt. Additionally, a cell-cell signalling event may induce the coordinated expression of these events. To identify genes involved in male tail tip morphogenesis, morphological mutants are being isolated and characterized. One such gene, lep-1, acts specifically to control adult fate in male tail tip cells and is being cloned to determine its molecular function and expression pattern. Epistatic interactions among identified genes will eventually be studied. The hypothesized cell-cell interactions in the induction of tail tip morphogenesis are being tested by selective ablation of multiple or single candidate cells with a laser microbeam. Other cellular processes potentially involved in tail tip morphogenesis are being investigated with markers and inhibitors of cellular components. To provide a precise microanatomical framework for these genetic and developmental analyses, the cellular architecture of the tail tip is being detailed by electron microscopy. The major educational activities take the form of undergraduate and graduate courses (mainly on evolution and evolutionary developmental biology), but participation in pre- service teacher education, undergraduate advising, and supervision of high school, undergraduate and graduate student research projects in the laboratory are also important. In the courses and laboratories, emphasis is placed on inquiry-centered, hands-on learning. Students are guided by question-based approaches to construct their own knowledge and skills. In particular activities, cooperature learning is encouraged to develop communication skills and the ability to work collaboratively as well as independently. A continuing emphasis in both coursework and assessment will be the development of language and problem- solving skills. The objectives of all of these activities are to develop in all of the participating students a solid foundation of knowledge in biology, a hearthy skepticism and creative ability to formulate constructive questions and hypothesis (and thus an appreciation of science as an approachable, dynamic, creative, human activity), a practical knowledge of the scientific method as a general problem-solving tool, and an ability to effectively communicate findings and concepts in both oral and written language.
