• Bacterial cells transmit memories to offspring

    From ltlee1@21:1/5 to All on Sun Sep 1 13:42:49 2024
    "Wytock cites the World War II Dutch famine as a famous example pointing
    to the possibility of heritable, non-genetic traits in humans. A recent
    study showed that the children of men, who were exposed to the famine in
    utero, exhibited an increased tendency to become overweight as adults.
    But isolating the ultimate causes for this type of non-genetic
    inheritance in humans has proved challenging.

    "In the case of complex organisms, the challenge lies in disentangling confounding factors such as survivor bias," Motter said. "But perhaps we
    can isolate the causes for the simplest single-cell organisms, since we
    can control their environment and interrogate their genetics. If we
    observe something in this case, we can attribute the origin of
    non-genetic inheritance to a limited number of possibilities -- in
    particular, changes in gene regulation."
    ..

    "In the case of E. coli, the entire organism is a single cell," Wytock
    said. "It has many fewer genes than a human cell, some 4,000 genes as
    opposed to 20,000. It also lacks the intracellular structures known to
    underlie the persistence of DNA organization in yeast and the
    multiplicity of cell types in higher organisms.Because E. coli is a well-studied model organism, we know the organization of the gene
    regulatory network in some detail."

    Reversible stress, irreversible change

    The research team used a mathematical model of the regulatory network to simulate the temporary deactivation (and subsequent reactivation) of
    individual genes in E. coli. They discovered these transient
    perturbations can generate lasting changes, which are projected to be
    inherited for multiple generations. The team currently is working to
    validate their simulations in laboratory experiments using a variation
    of CRISPR that deactivates genes temporarily rather than permanently.

    But if the changes are encoded in the regulatory network rather than the
    DNA, the research team questioned how a cell can transmit them across generations. They propose that the reversible perturbation sparks an irreversible chain reaction within the regulatory network. As one gene deactivates, it affects the gene next to it in the network. By the time
    the first gene is reactivated, the cascade is already in full swing
    because the genes can form self-sustaining circuits that become
    impervious to outside influences once activated.

    "It's a network phenomenon," said Motter, who is an expert in the
    dynamic behaviors of complex systems. "Genes interact with each other.
    If you perturb one gene, it affects others."

    https://www.sciencedaily.com/releases/2024/08/240828154929.htm

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