microRNAs differentiate neuronal cell types
July 31, 2014 | James Kohl
Excerpt: “In light of the fact that miRNAs have very precise expression patterns depending on the cell type, tissue and/or developmental stage; it is challenging to generalize a single mechanism to regulate their expression and to identify the target genes that each miRNA has during each stage of neurogenesis. Thus, the combination of bioinformatic tools and experimental techniques will help in the study of miRNAs role in early neurogenesis and how they, their target genes, and their regulators are integrated within the regulatory gene expression networks that determine each particular neuronal phenotype.”
My comment: In my model, the nutrient-dependent microRNAs (miRNAs) are the key triggers of all cell type differentiation in all cells of all individuals of all species. The epigenetically effected miRNA/messenger RNA (mRNA) balance controls cell type differentiation by the metabolism of nutrients to species-specific pheromones. The physiology of reproduction is controlled by pheromones, which allows ecological variation to lead to ecological adaptations via the supply of nutrients. Simply put, microRNAs differentiate cell type via the pheromones that control the nutrient-dependent physiology of reproduction, which controls nutrient-dependent biodiversity.
Although it is becoming clear that Convergent microRNA actions coordinate neocortical development via cell type differentiation that is nutrient-dependent and pheromone-controlled, not all researchers agree that cell type differentiation should be removed from the context of mutation-initiated natural selection and the evolution of biodiversity. For example: in A critical appraisal of the use of microRNA data in phylogenetics, the authors seemingly claim “…a Bayesian statistical approach that explicitly models the process of miRNA evolution may reveal the uncertainty of phylogenetic studies…” See also: Flaws emerge in RNA method to build tree of life.
By focusing on the evolution of microRNAs and statistics that link them to differentiation of cell types during different developmental stages in different species, the nutrient-dependent nature of the microRNAs that differentiate the cell types of all individuals in all species during their development is removed from consideration. There is no mention of nutrient-dependent pheromone-controlled epigenetic effects on microRNAs that link food odors to changes in the microRNA/messenger RNA balance and amino acid substitutions that differentiate cell types.
Thus, the most parsimonious and well detailed explanation of how ecological variation results in nutrient-dependent pheromone-controlled cell type differentiation via amino acid substitutions: Nutrient-dependent pheromone-controlled ecological adaptations: from atoms to ecosystems, is replaced prior to its publication with statistical analyses that eliminate half of what occurs in the context of biologically-based cause and effect. Instead, we see another article that attributes biodiversity to mutation-initiated natural selection, which includes evolution of the human brain and behavior, or to some other theory with no explanatory power as first noted in the context of the prepublication of another work Estimating Phylogeny from microRNA Data: A Critical Appraisal.
It seems likely that “…a Bayesian statistical approach that explicitly models the process of miRNA evolution…” may convince evolutionary theorists that they can continue to tout the pseudoscientific nonsense of their theories based on what “… may reveal the uncertainty of phylogenetic studies…” unless the phylogenetic studies are placed into the context of what Dobzhansky (1973) noted in “Nothing in Biology Makes Any Sense Except in the Light of Evolution: “…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.”
That parsimonious fact links nutrient-dependent pheromone-controlled ecological adaptations in yeasts to humans via the conserved molecular mechanisms of amino acid substitutions and cell type differentiation. See for examples: Signaling Crosstalk: Integrating Nutrient Availability and Sex and Feedback loops link odor and pheromone signaling with reproduction. Also, anyone who thinks that flaws have emerged in the method by which alternative splicings of pre-mRNA and amino acid substitutions that determine cell type differentiation in species from microbes to man is encouraged to look at the abstracts from presentations at the Yeast Genetics Meeting.
For example: Elucidating the Effects of Human Genetic Variation On Vitamin D Signaling links microbial fermentation of grains and yeasts from light-induced amino acid substitutions in plants and algae to the nutrient-dependent pheromone-controlled physiology of human reproduction via the conserved molecular mechanisms we detailed in our 1996 Hormones and Behavior review and adding the link across species to differentiation of cell types by vitamin-induced and sunlight-induced amino acid substitutions.