The total "in lineage" substitutions for ORFs in single copy relaxed core families were calculated as the distance from each tip to the root of the ML ribosomal protein phylogeny multiplied by the quantity of such ORFs in the genome sampled for that lineage (units: ORF.substitutions.site−).site−
Using transmitochondrial cybrids derived from patient fibroblasts with high heteroplasmy levels of single, large-scale mtDNA deletions, these authors demonstrated a replicative advantage for mtDNA deletions over wild-type molecules in the same cell under relaxed mtDNA copy number conditions following ethidium bromide-driven mtDNA depletion (25).
As the wall text accompanying the installation by FAT puts it, "FAT and their collaborators are relaxed about copying: the sources are out there to plunder". This approach to history and memory is very different from the one the postmodern pioneers Robert Venturi, Denise Scott Brown, Charles Moore and Aldo Rossi brought to architecture in the 1970s and '80s.
The total mtDNA content per cell for different prostate cell lines and the number of damaged (or relaxed) mtDNA copies per cell can be determined using an absolute quantification approach).
The creation of extra gene copies relaxed selective pressure allowing some copies to evolve new functions, while at least one of the genes maintained the original function.
During the evolution of duplicated genes, purifying selection is thought to be relaxed on one copy because of its redundant function; this relaxation should lead to an increased nucleotide substitution rate in one duplicate (e.g., [ 30- 32]).
This prompts speculation that the negative effects of gene expression level imbalances are diminished in vertebrates, thereby relaxing single-copy controls and allowing multicopy gene buffering of mutations that lead to extended exploration of protein sequence space.
Since selection is often relaxed on both copies of the gene after duplication, either the ancestral or the progeny copy can be inactivated.
After gene duplication some retained duplicated genes undergo asymmetric rate divergence and the faster evolving copy experiences relaxed constraint or positive selection [ 34, 35].
The CAI compares the codon usage of a gene to codon usage in highly expressed genes; hence, the reduction in the CAI values of derived paralogs suggests that selection for optimal codon usage has been relaxed in the derived copy.
