Genetic chimerism and ecological adaptation

From Many, One

Diverse mammals, including humans, have been found to carry distinct genomes in their cells. What does such genetic chimerism mean for health and disease?

By Elena E. Giorgi | April 1, 2015

Summary:CELLULAR PATCHWORK: Chimerism—the existence of genetically distinct cell lines within an individual—is probably much more common than once believed. It can result from a variety of sources, from organ transplantation, in which genetically distinct tissues are implanted into the body, to biological mutation that spawns cells with different chromosome numbers. Oftentimes, the concentration of a distinct cell line is so low that it is overlooked entirely. But even this low-level microchimerism, such as the presence of fetal cells in a mother’s body, may have consequences for health and disease.”

Excerpt 1) “For years the concept of a genetic chimera has sparked the imagination of writers, from Stephen King to Michael Crichton, presenting endless fodder for science fiction, horror, and even murder mysteries. But while most fictional works portray chimeras as an amalgam of two individuals, the truth is that the individuality of the distinct cell lines is lost as the two combine. Indeed, genetic chimerism is subtle, and may still often be overlooked if the second cell line exists at concentrations too low for our current technology to detect.”

Excerpt 2) “One of the genes involved in early epigenetic regulation is TRIM28. This gene mediates transcriptional control in certain regions of the chromatin and is thought to play a fundamental role in resetting the epigenome during embryonic development. Researchers in Singapore, at the Jackson Laboratory in Maine, and at Stanford University created epigenetic chimeras by disrupting the TRIM28 gene in mouse mothers.18 The scientists showed that not all cells in the resulting embryos had their epigenomes reset, as is expected following genomic reprogramming, but instead ranged from normal to completely unmethylated. This effectively created a chimeric mixture—with a disastrous outcome. Mouse embryos produced by TRIM28-deficient mothers did not survive more than five days postfertilization.”

My comment: See also: Interplay of TRIM28 and DNA methylation in controlling human endogenous retroelements and TRIM28 Represses Transcription of Endogenous Retroviruses in Neural Progenitor Cells
Greg Bear’s novels “Darwin’s Radio” and “Darwin’s Children” are unlike other science fiction. They link what is now known about the balance of viral microRNAs and nutrient-dependent microRNAs to the development of morphological phenotypes and behavioral phenotypes in humans without the pseudoscientific nonsense about mutations and evolution.
If Greg Bear was a scientist, his accurate representations of biologically-based cause and effect might be ignored because what he eloquently elucidated in fiction has become part of the creationist literature. That creationist literature integrates what is currently known about the nutrient-dependent biophysically constrained chemistry of RNA-mediated amino acid substitutions that differentiate all cell types in all genera via conserved molecular mechanisms. See for example: Viruses–Architects of the Brain?
Excerpt: “If ancient infections did not insert DNA sequences resembling certain viruses into mammal cells, then someone must have fashioned these mobile genetic elements from the beginning.2 That sounds like creation, an option that evolution’s defenders disdain.”
The problem with comparisons between the creationist literature and evolutionary theories becomes worse when placed into the context of this report: An Intrinsically Disordered Peptide from Ebola Virus VP35 Controls Viral RNA Synthesis by Modulating Nucleoprotein-RNA Interactions.
The interactions that control viral RNA synthesis appear to link an “Intrinsically Disordered Peptide” from virus-induced RNA-mediated amino acid substitutions to nutrient-dependent morphological phenotypes in the cell types of plants. The complexity of the phenotypes in plants is linked from the anti-entropic epigenetic effects of light to the nutrient-dependent pheromone-controlled physiology of reproduction in species from microbes to man via the conserved molecular mechanisms of biophysically constrained RNA-mediated protein folding.  That links the light-induced de novo creation of amino acids to the creation of differences in all cell types of all genera via the light-induced creation of this planet’s atmosphere.
See: Evidence for direct molecular oxygen production in CO2 photodissociation reported as: Making oxygen before life: Oxygen can form directly from carbon dioxide in upper atmosphere

“Previously, people believed that the abiotic (no green plants involved) source of molecular oxygen is by CO2 + solar light –> CO + O, then O + O + M –> O2 + M (where M represents a third body carrying off the energy released in forming the oxygen bond),” Zhou said in an email. “Our results indicate that O2 can be formed by carbon dioxide dissociation in a one step process. The same process can be applied in other carbon dioxide dominated atmospheres such as Mars and Venus.”

All experimental evidence from physics, chemistry, and molecular biology continues to attest to what serious scientists and Greg Bear, science fiction author, place into the context of an atoms to ecosystems model of biodiversity. That fact does not leave much “wiggle room” for theorists who make claims like this one: “…genomic conservation and constraint-breaking mutation is the ultimate source of all biological innovations and the enormous amount of biodiversity in this world. In this view of evolution there is no need of considering teleological elements” (p. 199). Mutation-Driven Evolution
Thank God, serious scientists are Combating Evolution to Fight Disease. That fact leaves only pseudoscientists to consider re-evolution of the bacterial flagellum occurred in 96 hours.  See: Evolutionary resurrection of flagellar motility via rewiring of the nitrogen regulation system,  reported as: Evolutionary Rewiring.
Excerpt: “Johnson and her colleagues have now discovered, however, that not only can giant evolutionary leaps happen, but they can do so in a reproducible way.”
My comment: I do not think the term “evolutionary leaps” applies to evolution of the flagellum in four days. The flagellum is obviously a nutrient-dependent pheromone-controlled ecological adaptation. The most likely origins of the nutrient-dependent adaptation is virus-induced changes in the thermodynamic cycles of protein biosynthesis and degradation in bacteria, which extends what is known about organism-level thermoregulation to virus-driven ecological adaptations in all genera via fixation of amino acid substitutions that differentiate cell types. It seems likely that all cell types exhibit the potential for chimerism that links entropic elasticity to increasing organismal complexity in the presence of ecological variation and epigenetic landscapes that must be linked to the physical landscape of DNA without the perturbed protein folding linked from mutations to physiopathology.

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