Cassandra Extavour is a Canadian geneticist, researcher of organismic and evolutionary biology, professor of molecular and cell biology at Harvard University, and a classical singer. The central focus of her research has revolved around evolutionary and developmental genetics.
Extavour was born and raised in a mixed race household. Her father was from Trinidad and Tobago and her mother was from Switzerland and Hungary. She didn’t realize she had an underlying interest in science until high school. Her performance in math and science was outstanding, which, as a result, led her to consider a career in science instead of becoming a musician or a baker as she had always thought she would be. Her interest in developmental genetics in particular began through a summer internship in the laboratory of Joe Culotti at the University of Toronto.
Extavour went on to receive an Honours Bachelor of Science degree at the University of Toronto. She later on also completed her Doctor of Philosophy in Madrid, for which her thesis was on germ cell selection in genetic mosaics. Her work was published in Proceedings of the National Academy of Science of the United States of America (PNAS) in 2001.
In 2003, Extavour conducted her postdoctoral research with Michael Akam, a zoologist and embryologist at Cambridge University, on the mechanisms of germ cell formation. The prevailing theory held that most animals formed their germ cells early in development as a result of molecules inherited from the mother. Popular model organisms, including flies and roundworms, all generate their germ cells that way. However, mice were an exception, in which those cells form later during development when signals coax some of the embryo’s cells to take the first step towards becoming eggs in females and sperm in males. Determined to understand the bigger picture, Extavour embarked on a first-of-its-kind review of existing data on the mechanisms that specify germ cells in a wide range of organisms, from jellyfish to turtles. She read more than 1000 academic papers on germ cells, and in nearly 300 of them, she found relevant information on the cells’ origins, which led her to conclude that the most common method of formation—and probably the oldest in evolutionary terms—is the process seen in mice.
In 2007, Extavour started her independent laboratory in the Department of Organismic and Evolutionary Biology at Harvard University as an Assistant Professor. She was promoted to Associate Professor in 2011 and to Full Professor in 2014. Some of Extavour’s research during the course of this time showed that bone morphogenetic proteins (BMPs) can help to induce primordial germ cells (PGCs) in the early stages of embryo development in a cricket. Extavour and her colleagues were able to specify that two BMPs, BMP8b and BMP4, help induce PGCs in this insect. This is significant because it was the first demonstration of a specific signalling pathway operating in the induction of embryonic germ cells in an invertebrate.
From 2010 to 2015, Extavour directed a national research collaborative called EDEN, which stands for Evo-Devo-Eco (evolutionary-developmental-ecological) Network. This organization, funded by the National Science Foundation, encouraged scientists to develop and share tools and techniques for use in a broader spectrum of organisms than the traditionally studied laboratory model organisms. Extavour believes that a number of deep evolutionary questions cannot be answered by examining only one organism, and therefore hopes that science will move past the model organism paradigm.
Reference
https://en.wikipedia.org/wiki/Cassandra_Extavour
https://www.nature.com/articles/d41586-019-02040-6
Applied Plant Ecology Winter 2020 