Life Sciences Seminar: Cassandra Extavour


Feb. 2, 2018, 1pm to 2:30pm

Office/Remote Location



Cassandra Extavour, professor in the Departments of Organismic & Evolutionary Biology, and Molecular & Cellular Biology at Harvard University, will be the featured speaker at an upcoming School of Life Sciences seminar. Her talk is titled, "From soma to germ line: origin, mechanism, and evolution of the oskar gene."

Decades of modern evolutionary developmental genetics has revealed that an enormous proportion of the genes that control animal development are ancient and conserved. Most of these genes, including all major signaling pathways and many regulators of tissue identity, are not only found in the genomes all animals, but also function in highly similar ways across animals. It therefore seems clear that most genes controlling embryonic development are ancient, inherited from the last common ancestor of all animals, and have retained the same essential functions over more than 500 million years of evolution. In contrast, genes that appear to be specific to only some organisms, or that have changed their function significantly in one lineage versus another, are much less well understood. Here we present our work on a gene that falls into both of these categories: oskar. The oskargene is found only in insects, and appears absent not only from the genomes of other eukaroytes, but also from those of bacteria and archaea. In some insects oskar plays an essential role in establishing the germ line, but in others it is dispensable for germ line development, instead playing roles in neural patterning and function. She presents evidence that horizontal gene transfer from a bacterial genome led to the origin of oskar, that the ancestral role of oskar was in the nervous system, and that the evolution of specific biophysical changes in the Oskar protein facilitated the evolution of a novel role in germ line formation in higher insects.

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This event is free and open to the public.

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School of Life Sciences