It would further change the designation of genes with functions upstream in the signal transduction pathway from essential to non-essential fitness modifying or fitness neutral genes.
The designation of a gene or regulatory element within this scheme, i.e. an essential gene, a non-essential fitness modifying gene, a fitness neutral gene, a tumor suppressor/gatekeeper gene, an oncogene or a caretaker gene is fundamental for lineage selection effects through changes of physical and functional genome redundancy.
Genes or regulatory elements displaying functions which modify the fitness of a CCL in a given clinical stage or microenvironment may be considered non-essential fitness modifying genes while genes with functions without any apparent consequence on cellular fitness will be considered fitness neutral genes.
In particular, the gene being modeled was in all cases essential to fitness: the absence of protein activity would lead to zero fitness, even neglecting any cost of the protein.
If their expression levels are the same, a protein essential to fitness should have approximately the same evolutionary rate as a protein that makes only a small contribution to fitness.
Cas9-expressing cell pools and/or cell clones were infected with single guide RNA (sgRNA) libraries37,38 and cultured for 2 3 weeks to allow sufficient time for the depletion of cells with inactivated essential and/or fitness genes.
Thus plasmids may initially be involved in virulence, but once the virulence genes are inserted into the chromosome, the plasmid genes are no longer essential for fitness.
Taken together, our findings suggest that both eIF4G isoforms can support expression of proteins essential for fitness under a wide variety of growth conditions.
CTR1, the high-affinity transporter gene required for copper uptake, was essential for fitness in two of the three screens that we performed [see Additional file 2].
Nonetheless, the protein sequence is under stronger selection and evolves more slowly than most of the others represented in the figure, including several that are essential to fitness.
