Subject: Page Title
From: <Saved by Windows Internet Explorer 7>
Date: Thu, 15 Jan 2009 15:33:51 -0500

Elhanan
Borenstein

Stanford
University

Reverse
Ecology: From Large-Scale Analysis of Metabolic Networks, Growth Environments
and Seed Sets to Species Interaction and Metagenomics

The
topology of metabolic networks may provide important insights not only into the
metabolic capacity of species, but also into the habitats in which they evolved.
In this talk I will present several analyses of metabolic networks and show how
various ecological insights can be obtained from genomic-based
data.

I
will first introduce various factors that affect the structure of metabolic
networks, and specifically the environmental and genetic determinants that
affect network modularity. I will then present the first large-scale
computational reconstruction of metabolic growth environments, analyzing the
metabolic networks of hundreds of species and using a graph-theory based
algorithm to identify for each species a set of seed compounds that must be
exogenously acquired. Such seed sets form ecological "interfaces" between
metabolic networks and their surroundings, approximating the effective
biochemical environment of each species. Computational reconstruction of
metabolic networks of ancestral species and phylogenetic analysis of the seed
sets reveal the complex dynamics governing gain and loss of biosynthetic
capacity across the phylogenetic tree.

I
will further present an extension of this framework, accounting for interactions
between species, by introducing a pair-wise, topology-based measure of
biosynthetic support, which reflects the extent to which the nutritional
requirements of one species could be satisfied by the biosynthetic capacity of
another. I will show that this measure is aligned with host-parasite
interactions and facilitates successful prediction of such interactions and
their evolution on a large-scale.

*****

Dr.
Elhanan Borenstein is a postdoctoral fellow at Stanford University and at the
Santa Fe Institute. Dr. Borenstein's research is concerned with Evolutionary
Systems Biology, focusing on the interplay between the evolutionary process and
the organization of biological systems. Specifically, he uses a computational,
large-scale, systems level approach to study metabolic networks and to identify
the environmental and genetic factors that determine their structure and
evolution. A more theoretical part of his research concerns the study of
fundamental phenomena in evolutionary dynamics, with an emphasis on the relation
between genotypes and phenotypes and the way this relation constrains the
evolutionary process. This work spans various topics, including the evolution of
mutational robustness, the effect of plasticity on genetic evolution, and the
constraints induced by development and by regulatory epistasis on phenotypic
diversity. Dr. Borenstein also has extensive research and development
professional experience in the hi-tech industry, where he held several top
management positions. Dr. Borenstein was part of the Special Program for
Outstanding Students in Tel-Aviv University, and was the recipient of the
Yeshaya Horowitz Association Scholarship in Complexity Science. He received the
prestigious Philip Steinmetz Fellowship from the Santa Fe Institute, as well as
several teaching awards. Dr. Borenstein received his B.Sc. (summa cum laude) in
physics and computer science and his Ph.D. (with distinction) in computer
science from Tel-Aviv University.

4:15pm

B17
Upson Hall

Tuesday,
January 20, 2009

Refreshments
at 3:45pm in the Upson 4th Floor Atrium

Computer
Science

& Information
Science

Colloquium

Spring
2009

www.cs.cornell.edu/events/colloquium

www.cs.cornell.edu/events/colloquium