Year: 2022

MOLECULAR SELECTION. "Purifying selection, the purging of deleterious variants from the population, is the most common mode of operation of selection. At the molecular level, purifying selection is commonly seen in the maintenance of sequence motifs whose degradation decreases the fitness of the organism." https://lnkd.in/drMDPh6 View in LinkedIn

AVOIDANCE SELECTION. "However, there is evidence that selection can also act to avoid a particular sequence motif if its presence in a given context is deleterious. This phenomenon, that we term “avoidance selection,” constitutes another facet of purifying selection and has been documented in a wide variety of biological systems." https://lnkd.in/drMDPh6 View in LinkedIn

EXONIC SPLICE ENHANCERS. "Here we test a further potential case of avoidance selection. We hypothesized that there could be avoidance of exonic splice enhancers in genes that do not contain introns. Exonic splice enhancers are short nucleotide motifs that are exceedingly common in vertebrate exons, especially near the splice sites." https://lnkd.in/drMDPh6 View in LinkedIn

MAJOR EVOLUTIONARY ROLE. "Importantly, exonic splice enhancers appear to play a major role in shaping patterns of vertebrate sequence evolution. These motifs are under purifying selection, as evidenced both by their decreased rate of evolution at synonymous and nonsynonymous sites." https://lnkd.in/drMDPh6 View in LinkedIn

EXON CONSERVATION. "Exonic splice enhancers' "abundance at exon ends explains, at least in part, why exon ends tend to be more conserved than exon cores." https://lnkd.in/drMDPh6 View in LinkedIn

EXON SKEWING. "In addition, both codon and amino acid usage are skewed near exon ends in a way that is consistent with an effect of exonic splice enhancers." https://lnkd.in/drMDPh6 View in LinkedIn

HYPOTHESIS. "We hypothesized that exonic splice enhancers might be avoided in intronless genes, as the recruitment of splicing factors to the transcript could theoretically cause the activation of cryptic splice sites and thus lead to inappropriate RNA processing." https://lnkd.in/drMDPh6 View in LinkedIn

ADDITIONAL FUNCTIONS. "Our data are thus consistent with some exonic splice enhancers having functions beyond splice promotion." https://lnkd.in/drMDPh6 View in LinkedIn

QUESTION 1. "What Could be the Function(s) of exonic splice enhancers in Intronless Genes?" https://lnkd.in/drMDPh6 View in LinkedIn

QUESTION 2. "Why Would Genes that Have a Higher Density of Introns be More Enriched in exonic splice enhancers?" https://lnkd.in/drMDPh6 View in LinkedIn