SANS Seminar Series

Harvard geneticist to focus on gene transfer and animal evolution

The SANS Spring Seminar by Harvard Professor Dr. Cassandra Extavour on May 1 has been canceled. It will be rescheduled at a later date.

A Harvard professor, geneticist and researcher is the speaker May 1 at the final School of Agricultural and Natural Sciences’ Spring Seminar Series for 2025.

Dr. Cassandra Extavour is the Timken Professor of Organismic and Evolutionary Biology and of Molecular and Cellular Biology at Harvard and a Howard Hughes Medical Institute Investigator.

Her presentation is titled “”Alien Invasion: New Genes and New Biology Generated by Sequence Transfer Across Kingdoms of Life.” 

The seminar will be held at 11 a.m. in the Carver Hall Auditorium on the University of Maryland Eastern Shore campus.

Extavour’s research is focused on understanding early embryonic development, the genes that control this development, the evolutionary origins of these genes and how their functions have changed over evolutionary time.

Animals are capable of an astonishing array of complex biology that appears absent in single-celled organisms. Evolving these biological properties (including physiology, development and behavior) was possible largely thanks to the emergence of new gene regulatory networks. 

Where did the genes in these networks come from? Some of them were present in the single-celled eukaryotic ancestors of animals but others appear entirely novel, with no closely related genes found in other animals. 

Researchers have found evidence for a surprisingly widespread phenomenon whereby new genes are created by fusing fragments of bacterial and eukaryotic genes together, generating novel chimeric genes in the genomes of a broad range of complex organisms. 

Applying developmental, biochemical and computational assays to one of these chimeric genes provided evidence that it came to occupy a new role in insect reproduction, changing the way that many insects ensure they can make eggs and sperm. 

Looking closely into some animals with a surprising number of chimeric genes in their genomes revealed another striking mechanism of genetic novelty. We discovered that up to 11% of the protein-coding genes in a fungus gnat (Bradysia coprophila) were likely acquired by horizontal transfer from distantly related arthropods. 

Synteny, sequence composition, structural prediction, gene expression, and phylostratigraphy data suggest that these genes were acquired early in the evolutionary history of these animals, and equip them with new physiological abilities, including withstanding high levels of DNA damage and digesting nutrients found in their ecological niche. 

This work enhances our understanding of how gene transfer within and between kingdoms of life contributed to the evolution of animal complexity.

Extavour is a native of Toronto, Canada and obtained her bachelor’s degree in molecular genetics and molecular biology at the University of Toronto. She obtained her Ph.D. at the Severo Ochoa Center for Molecular Biology at the Autonomous University of Madrid in Spain.

After postdoc work at the Institute for Molecular Biology and Biotechnology in Crete, Greece, and at the University of Cambridge, she established her independent laboratory as an assistant professor at Harvard.