Also reported as:
In humans, researchers used a technique called 14C/12C bomb pulse dating to measure turnover. The technique is based on the fact that high levels of radioactive carbon (14C) were released into the atmosphere during the 1950s and 1960s, when open-air nuclear bomb testing occurred following the Second World War. Researchers can take samples from cells – in this case, purified H3.3 samples from brain cells of postmortem human brains, and determine present 14C/12C ratios from the time of death against past atmospheric levels from the time of the subject’s birth. As with the rodent observations, the researchers found that H3.3 turnover occurs in the human brain throughout life.
Additionally, the researchers deliberately manipulated H3.3 dynamics in both embryonic and adult neurons, confirming the role of histone turnover in neuronal plasticity. The findings thus establish histone turnover as a critical, and new, regulator of cell-type specific transcription in the brain.
“Histone turnover, shown through our work with H3.3, is essential for the behavior of brain cells,” said Dr. Maze. “Furthering our understanding of how the brain works, learns, forms new memories and reacts to changes in the environment can help us to find new ways to treat neurodegenerative diseases and mental illness.”
Attempts to discuss this among neuroscientists can be found on this Neuroscience FB page.
Addendum: My understanding of cancer links it from RNA-directed DNA methylation and RNA-mediated amino acids substitutions that are linked via “histone turnover” and cell type differentition in the brain. My understanding is based on the young earth creationist perspective, which I learned about from a physician. He claimed that something more than sun exposure must be responsible for the different types and number of different non-malignant and malignant skin cell types that were removed during ~ 20 different surgeries. When I told him that I managed the medical laboratory at the Nevada Test Site, which is where open-air nuclear bomb testing occurred following the Second World War, and that I had also worked in the down-wind area (Caliente, Nevada) and (Milford, Utah) for several years, he said: “That would do it!”
I hired other medical laboratory scientists to work at both locations, and they traveled from St. George, Utah. It is a “hotbed” of skin cancer and located between the two medical laboratory facilities that I subsequently managed.
Anecdotal and experimental evidence of biologically-based cause and effect have continued to support the views of the young earth creationists, who are less likely to believe in any pseudoscientific nonsense about mutations and evolution — compared to social scientists.
The obvious epigenetic links from gut microbes to cell type differentiation in the human brain have been virtually ignored despite overwhelming experimental evidence of the systems complexity manifested in all genera. Evolutionary theorists are largely responsible for the overwhelming ignorance of how cell type differentiation occurs because they have placed it into the context of mutations and evolution.
See, for example: Mutation-Driven Evolution, which was published on the same day as: Nutrient-dependent/pheromone-controlled adaptive evolution: a model
Protein folding is biophysically constrained via RNA-mediated nutrient-dependent amino acid substitutions See also:
For 50 years, the “protein folding problem” has been a major mystery. How does a miniature string-like chemical — the protein molecule – encode the functions of living organisms: how our muscles exert force, how our immune systems reject pathogens, how our eyes see our surroundings, how plants convert solar energy, and all the rest. Huge progress is being made. Moreover, these amazing nano-machines could play important roles in health and disease and commerce in the future.