Latent Memory Of Cells Comes To Life (5/23/2007)

New research has examined the mechanisms behind latent cell memory, which can come to life and cause previously non-existent capacities suddenly to appear. Special yeast cells for example, can abruptly change from being of a single sex to hermaphrodite.

Background

Researchers from the Niels Bohr Institute have used mathematical models and computer simulations to examine fundamental mechanisms of cell memory. The research is an interdisciplinary cooperation between molecular biologists and physicists, and has just been featured on the cover of the prestigious science journal CELL.

Dormant capacities

Our genetic material - DNA – is a blueprint for how we look and are. This genetic material is very stable and it is faithfully transmitted to our descendants. Once in a while though, a change occurs to the DNA, either large or small. Changes in the DNA creating new functions normally arise by a slow and gradual process that involves natural selection operating over many generations.

Sometimes however, dramatic and very sudden changes are observed in one individual in the absence of any kind of change to the DNA:

"The explanation for the sudden changes is that it is not the DNA itself that is altered - it is its immediate surroundings that change and thereby cause a cell to activate some of its dormant capacities" says Kim Sneppen, professor in Biophysics at the Niels Bohr Institute.

Same inheritance – different traits

In the practical experiment molecular biologists used a mutant of a yeast cell which was bi-stable, in that it could become either of a single sex or hermaphrodite. The experiment showed that a spontaneous change occurred in the yeast cells about every 2000 cell-generations.

By building a mathematical model based on positive feedback from the microscopic state of the nucleosomes, the research group could simulate the experimental results and in this way gain insight into the mechanisms by which living cells with identical DNA can achieve extreme differentiation.

Note: This story has been adapted from a news release issued by the University of Copenhagen

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