Both overall levels of replication and breadth of tissue tropism may be positively correlated with virulence.
We describe a computational pipeline that uses microarray data to assess the level of expression and breadth of tissue profiles for transcripts with distinct first exons regulated by alternative promoters.
It is probable then, that there are differences in selection on protein sequences of males and females independent of the breadth of tissue expression.
To examine the breadth of tissue expression of genes represented by the top 100 ranked clones, we mined the summary SAGE expression data from the Cancer Gene Anatomy Project http://cgap.nci.nih.gov/.
In multicellular organisms the correlation between dN/dS and expression breadth (number of tissues where genes are expressed) is often stronger than with the actual level of gene expression [ 54, 55, 61].
The breadth of this tissue and species data allows us to show that downregulation of target genes by miRNAs is more pronounced between tissues than between species and that downregulation is more pronounced for genes with fewer binding sites for expressed miRNAs.
Expression Breadth, the number of tissues where the probe set has been expressed above the A-value threshold (7.0), was also calculated.
Two measures of expression level were defined: total expression level, which is the sum of the total 18 tissues' EST, and expression breadth, the numbers of tissues in which EST was found.
Levels of selective constraint acting on a gene are affected by a number of factors, including gene expression level (measured, for instance, as the number or concentration of transcripts in the cell) and breadth (the number of tissues in which a gene is expressed) [ 7, 50- 52], codon bias [ 51, 53], connectivity of the encoded proteins [ 14- 16], and the number of paralogs [ 54, 55].
The two factors with the strongest associations with other data types in humans are expression breadth (the number of tissues one protein is expressed in) and phyletic age (defined by the evolutionarily most distant species where homologs can be found) [ 1, 2].
