De Witt Sumners
Florida State University


2006 Sloan Lecture Series

Rice University
St. Thomas University


Calculating the Secrets of Life: Mathematics in Biology and Medicine

5:30-6:30pm Wednesday, November 15 - Anderson 103, University of St. Thomas
(public lecture - refreshments will be served before and after the lecture)

Abstract: The human body is an extremely complicated biological system. Spurred by spectacular recent progress, biology and medicine are experiencing an explosion of data. In order to convert this fire hose of data into usable knowledge, mathematics and computation (both old and new) are needed to build models and navigational tools. This talk is intended for a general audience, and will briefly discuss a few applications to show the impact that mathematics can have in biology and medicine: in the cell (understanding how enzymes operate on DNA); in the heart (controlling fibrillation); and in the brain (understanding brain function).


DNA Topology

4-5pm Thursday, November 16 - Keck Hall 100, Rice University
(special lecture for undergraduates - tea to precede the lecture in Herman Brown 438)

Abstract: Cellular DNA is a long, thread-like molecule with remarkably complex topology. Enzymes that manipulate the geometry and topology of cellular DNA perform many important cellular processes (including segregation of daughter chromosomes, gene regulation, DNA repair, and generation of antibody diversity). Some enzymes pass DNA through itself via enzyme-bridged transient breaks in the DNA; other enzymes break the DNA apart and reconnect it to different ends. In the topological approach to enzymology, circular DNA is incubated with an enzyme, producing an enzyme signature in the form of DNA knots and links. By observing the changes in DNA geometry (supercoiling) and topology (knotting and linking) due to enzyme action, the enzyme binding and mechanism can often be characterized. This expository talk will discuss topological models for DNA strand passage and exchange, introducing the tangle model for analysis of DNA site-specific recombination experiments.


DNA Knots Reveal Chiral Packing of DNA in Phage Capsids

4-5pm Friday, November 17 - Herman Brown 227, Rice University

Abstract: Bacteriophages are viruses that infect bacteria. They pack their double-stranded DNA genomes to near-crystalline density in viral capsids and achieve one of the highest levels of DNA condensation found in nature. Despite numerous studies some essential properties of the packaging geometry of the DNA inside the phage capsid are still unknown. Although viral DNA is linear double-stranded with sticky ends, the linear viral DNA quickly becomes cyclic when removed from the capsid, and for some viral DNA the observed knot probability is an astounding 95%. This talk will discuss comparison of the observed viral knot spectrum with the simulated knot spectrum, concluding that the packing geometry of the DNA inside the capsid is non-random and writhe-directed.

Link to the Rice poster and the University of St. Thomas poster

co-sponsored by the Rice University Mathematics Department, the University of St. Thomas Mathematics and Biology Departments, and a grant from the Sloan Foundation

Please send comments to Shelly Harvey - shelly at math.rice.edu.