Liran Carmel (NIH/NLM/NCBI)
 Sept 27, 2005
 11:00 AM B2 Seminar Library


Several studies have attempted to infer the intron content of early eukaryotes 
and the evolutionary landscape of spliceosomal introns. Due to partial modeling 
of the problem, no method is complete and the results of these studies are contradicting. 
We suggest a model of evolution which is far more realistic. In particular, 
it takes into account gene-specific intron gain and loss rates, branch-specific 
intron gain and loss coefficients, invariant sites incapable of intron gain, 
and rate variability of both gain and loss which is gamma-distributed across sites. 
We have developed an expectation-maximization algorithm to estimate the parameters 
of this model from the observed data. Our results reject the extreme views 
of gain-dominated evolution and loss-dominated evolution, and instead suggest 
a diverse landscape.