ABSTRACT

When the human genome was first sequenced, several surprises were unveiled. First, the number of genes that code for a human are relatively similar in number to those that code for a fruitfly or a common worm, two species with much smaller genomes that were also presumed to be much less complex. Second, those coding genes take up only about 2% of the human genome, leaving a very large fraction of the genome with no known functional role. Borrowing a turn of phrase from the world of astronomy, this non-coding 98% of the genome came to be known as genomic “dark matter.” Extensive follow-up studies have revealed functional roles for some of the non-coding genomic elements. A small percent of the genome encodes regulatory sequences that control when and where our genes function. Another small percent represents structural sequences – essentially spacers that keep our genes well-separated and our chromosomes intact. A surprisingly large 45% of the human genome derives from genomic parasites called “jumping genes,” or transposable elements. These “jumping gene” transposons have the ability to mobilize from one part of the genome to another; some are directly derived from viral sequences that inserted themselves into our genomes for the purpose of taking over infected cells. The human body devotes enormous resources to keeping these transposons in place, preventing the mutations that can be caused when they mobilize into new genomic locations. While these transposon defense systems are usually effective, occasional failures in transposon control have been shown to cause human diseases like hemophilia and cancer. More recently, a subset of these jumping genes that derive from viral sequences have been implicated in the neurodegenerative disease Amyotrophic Lateral Sclerosis (ALS). This talk will review the biology of transposons, the mechanisms that normally silence them, and the evidence that uncontrolled transposon activity may cause ALS.

About the Speaker:

Molly Gale Hammell received her BS in Physics from the College of William & Mary and her PhD in Physics & Astronomy from Dartmouth College. She switched fields from astronomy to computational biology during her postdoctoral fellowship in the lab of Victor Ambros at UMASS Medical School. She now has her own lab at Cold Spring Harbor Laboratory in New York, where she uses tools from molecular genetics and computational biology to study the genomic parasites called Transposable Elements. She has won awards for her research including a Ruth Kirschstein Award from the National Institutes of Health and is a Milton Cassel Scholar of the Rita Allen Foundation.