Second, a higher proportion of singletons in the 5'UTR than in synonymous sites of protein coding regions (Table 2) implied that the effect of selection has kept deleterious mutations at low frequencies.
To keep this deleterious capacity in check, the cell has evolved mechanisms to maintain tight regulatory control of copper storage and transport [ 1].
As DNA end joining would be detrimental to chromosome ends, it was though that Ku has to be kept away from telomeres to prevent deleterious telomere-telomere fusion.
Two processes exist, however, that can keep this long-term accumulation of deleterious mutations from occurring.
With a continuous fitness scale, apart from neutral and inviable sequences, we would have to keep track of slightly and strongly deleterious as well as advantageous sequences, and would consequently need a much more elaborate mathematical procedure to account for the contributions from these different fitness classes.
While the extended daylight hours afford us more time to be outdoors and active, we still need to keep in mind that sun exposure can be deleterious to our skin health.
This peculiar nonrandom functional organization of hubs and spokes might have evolved to keep the interactome healthy and robust against random deleterious genetic or transcriptional errors in the genome.
We have seen in the previous paragraph that, based on calculations for a single gene, a drop of 0.25 in fertility would keep up with the rate of 0.17 new deleterious recessive mutation, i.e. one per genome every six generations.
The vast majority of mutations affecting fitness are deleterious; therefore, there is selection pressure to keep mutation rates low.
Excess or uncontrolled transposition is clearly deleterious, and several mechanisms by which cells can keep RTEs tightly repressed have been documented [ 15].
