RNA-mediated repurposing in microbes and adaptations in primate brains

By: James V. Kohl | Published on: March 9, 2015

Human-specific gene ARHGAP11B promotes basal progenitor amplification and neocortex expansion

Excerpt: “…the C-terminal 47 amino-acids of ARHGAP11B (after lysine-220) constitute not only a unique sequence, resulting from a frameshifting deletion (fig. S10), but also are functionally distinct from their counterpart in ARHGAP11A.”
My comment: Co-author Svante Paabo is the senior author of this 2003 publication: Natural Selection on the Olfactory Receptor Gene Family in Humans and Chimpanzees
The 2015 publication was reported as:

A gene for brain size only found in humans

Excerpt: “ARHGAP11B is the first human-specific gene where we could show that it contributes to the pool of basal brain stem cells and can trigger a folding of the neocortex. In that way, we managed to take the next step in tracing evolution”, summarizes Wieland Huttner.
My comment: The authors report the contribution of amino acid substitutions to primate brain development as if a human-specific gene had somehow automagically evolved outside the biophysical constraints of the chemistry of nutrient-dependent RNA-directed DNA methylation and RNA-mediated amino acid substitutions that differentiate the cell types of all individuals in all species.
Are they pretending not to know that Dobzhansky (1973) wrote “…the so-called alpha chains of hemoglobin have identical sequences of amino acids in man and the chimpanzee, but they differ in a single amino acid (out of 141) in the gorilla.”
See also: Evolutionary resurrection of flagellar motility via rewiring of the nitrogen regulation system
Excerpt: NtrC shares 30 percent amino acid identity with FleQ, suggesting the proteins may be able to minimally cross-react with each other’s target genes.
My comment: The fact that RNA-directed DNA methylation and RNA-mediated amino acid substitutions differentiate cell types in all individuals of all species from microbes to primates seems clear. Why would anyone continue to frame their results in the context of mutations and evolution?
See also: RNA-mediated “repurposing” is nutrient-dependent and pheromone-controlled

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