For recent support of our claims from 23 years ago, see: Sexual dimorphism of miRNA signatures in feto-placental endothelial cells is associated with altered barrier function and actin organisation (Dec 2019)
We used our well established model of fetal endothelial cells isolated from placenta (fpEC) and analysed sexual dimorphic miRNA expression and potentially affected biological functions.
Functional pathways most significantly regulated by these miRNAs included ‘Adherens junction’, ‘ECM receptor interaction’ and ‘Focal adhesion’. These pathways control monolayer barrier function and may be paralleled by altered cytoskeletal organization.
See for review: From Fertilization to Adult Sexual Behavior (Dec 1996)
Here the “environment” involved can be that within a DNA segment. We also expand the notion of “biologically based sex differences.” Although many, and perhaps most, important sex differences arise from gonadal and hormonal development, also important are sex differences which are neither gonadal nor hormonal.
See our section on molecular epigenetics. You can link our claims about the nutrient-dependent pheromone-controlled alternative splicing of pre-mRNA to miRNA-mediated fixation of amino acid substitutions and to sexual differentiation of cell types from yeasts to humans.
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.
For support of ridiculous theories that might link abiogenesis from the evolution of self-replicating ribozymes (1) to the biophysically constrained (2) topology of supercoiled DNA, which protects all organized genomes from the virus-driven degradation of messenger RNA and stress-linked pathology, see:
“Ecologically relevant mating cues (sometimes known as “magic traits” [2,6]) are now predicted to be widespread in nature [6,7], and the last few years have seen considerable progress in our understanding of their genetic basis.”
(1) Lipid Encapsulation of Self-Replicating Ribozymes by Nurse Andrew Jones
(2) Dna Topology by Nurse Andrew Jones