Improving the specificity of high-throughput ortholog prediction

Background  

Orthologs (genes that have diverged after a speciation event) tend to have similar function, and so their prediction has become an important component of comparative genomics and genome annotation. The gold standard phylogenetic analysis approach of comparing available organismal phylogeny to gene phylogeny is not easily automated for genome-wide analysis; therefore, ortholog prediction for large genome-scale datasets is typically performed using a reciprocal-best-BLAST-hits (RBH) approach. One problem with RBH is that it will incorrectly predict a paralog as an ortholog when incomplete genome sequences or gene loss is involved. In addition, there is an increasing interest in identifying orthologs most likely to have retained similar function.     

Cardioelectric field on the atrial surface in pigs

The form and distribution of extracellular cardioelectric potentials and the sequence of the excitation wave propagation on epicardium of the pig atria were studied by the method of multichannel synchronous cardioelectrotopography. The studies have shown that in pig the excitation wave breaks on epicardium of the right atrium at the base of the upper vena cava. Negative initial atrial complexes are registered in this area. Two fronts of excitation wave spread from the zone of initial epicardial activation: one--to upper segments of dorsal and ventral sides of the right atrium, the second--to inter-atrial septum. The excitation wave comes to the left atrium with a delay relative to the beginning of depolarization of the right atrium. On account of the successive movement of the front of the excitation wave from pacemaker the two-phase potentials are formed on greater part of the epicardium of the pig atria. The lower part of the auricle of the left atrium is depolarized in atrial epicardium in the last turn. The sequence of excitation wave propagation in atrial epicardium close to ravenous (dog) and ungulate (sheep) animals and man is typical for the pig, but herewith the differences in time of covering the atria with excitation do exist.