Conclusion: “…delineating the epigenetic regulation of neuronal development is crucial to our understanding of intellectual-disability disorders caused by mutations in epigenetic modifying enzymes. As a whole, our findings highlight the complexity and functional diversity of Snf2h-containing CRCs during brain development, and their roles in controlling chromatin organization as cells modulate their chromatin environment from a ‘largely open’ progenitor state to the ‘highly restricted’ state of a fully differentiated neuron during cerebellar morphogenesis and neural maturation (Fig. 9i)60.
Excerpt: “ATP-dependent chromatin remodelling proteins that assemble, reposition and space nucleosomes, and are robustly expressed in the brain.”
My comment: ATP-dependent chromatin remodelling seems likely to be nutrient-dependent.
If so, it might link ecological variation in nutrient availability to ecological, social, neurogenic, and socio-cognitive niche construction via the conserved molecular mechanisms of nutrient-dependent pheromone-controlled amino acid substitutions that differentiate the cell types of species from microbes to man.
Cell type differentiation appears to enable the ecological adaptations in morphological and behavioral phenotypes that are perturbed when nutrient stress or social stress alter protein folding, which leads to mutations.
It does not seem likely that mutations and natural selection somehow lead to the manifestation of biodiversity that theorists claim has evolved. If there is no model for that, this experimental evidence appears to refute neo-Darwinian theory (again).
As always, I would be grateful if anyone could tell me about any experimental evidence of biologically-based cause and effect that appears to support the invention of neo-Darwinian theory and definitions that were used to make it seem that mutations and natural selection are responsible for the evolution of biodiversity, which this report — and all others that I have read — suggest results from ecological variations that lead to ecological adaptations in species from microbes to man via nutrient-dependent chromatin organization, which appears to be pheromone-controlled.
See for instance our 1996 review for information on sex difference in cell type differentiation that are probably nutrient-dependent and pheromone-controlled in species from yeasts to mammals.
Excerpt: Yet another kind of epigenetic imprinting occurs in species as diverse as yeast, Drosophila, mice, and humans and is based upon small DNA-binding proteins called “chromo domain” proteins, e.g., polycomb. These proteins affect chromatin structure, often in telomeric regions, and thereby affect transcription and silencing of various genes (Saunders, Chue, Goebl, Craig, Clark, Powers, Eissenberg, Elgin, Rothfield, and Earnshaw, 1993; Singh, Miller, Pearce, Kothary, Burton, Paro, James, and Gaunt, 1991; Trofatter, Long, Murrell, Stotler, Gusella, and Buckler, 1995). Small intranuclear proteins also participate in generating alternative splicing techniques of pre-mRNA and, by this mechanism, contribute to sexual differentiation in at least two species, Drosophila melanogaster and Caenorhabditis elegans (Adler and Hajduk, 1994; de Bono, Zarkower, and Hodgkin, 1995; Ge, Zuo, and Manley, 1991; Green, 1991; Parkhurst and Meneely, 1994; Wilkins, 1995; Wolfner, 1988). That similar proteins perform functions in humans suggests the possibility that some human sex differences may arise from alternative splicings of otherwise identical genes.
My comment: The link from the epigenetic landscape to the physical landscape of DNA in the organized genomes of species from yeasts to Drosophila, mice, and humans was made clear by our co-author, Teresa Binstock, in the context of molecular epigenetics and epigenetic imprinting more than 17 years ago. Nothing but confirmations of cause and effect have been published since then and yet neo-Darwinian theory has continued to be touted in the absence of any experimental evidence to support ridiculous claims.
MBD2 and MeCP2 regulate distinct transitions in the stage-specific differentiation of olfactory receptor neurons is but one of many articles published during the past 1.5 decades that should have called attention to the fact that our model of epigenetic cause and effect had replaced evolutionary theory with evidence of how ecological adaptations occur. It will be interesting to see how much longer it takes for evolutionary theorists to admit that they never really knew anything about biologically-based cause and effect, but believed in a ridiculous theory rather than learn anything about molecular biology.