UCLA Bioinformatics Program

Speaker: Christopher Lee, Dept. of Chemistry & Biochemistry, UCLA

When: Mon., Sep. 29, 2008, 4 pm

Where: CNSI Auditorium

Abstract

The Down syndrome cell adhesion molecule (Dscam) gene produces combinatorial diversity of immunoglobulin variable domains through alternative splicing (instead of DNA recombination as in mammalian immunoglobulin rearrangement), and has important functions in both the nervous system and the immune system.  We have performed extensive phylogenetic analyses of 20 arthropod genomes (each containing about 100 alternative exons encoding related Ig half-domains or domains), to reconstruct the detailed history of exon duplications that built this remarkable system over 450 million years of arthropod evolution.  The small size, diversity, and large number (nearly 2000) of these duplicated exons raised significant methodological challenges, which we have addressed by developing a high-speed analysis that combines outgroup information, duplication analysis, and monophyletic confidence estimation.  These data provide a remarkably detailed picture of how complex gene structure evolves, and even reveal clear indications of the likely molecular mechanism that produced these genomic duplications (and loss events), namely a self-reinforcing cascade of staggered homologous recombination events.

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