DNA dethroned


Is DNA really the blueprint of life, encoding all of the information needed to make an organism?  Daedalus has his doubts.  He recalls that patterns of cilia in paramecia are directly templated off the parental patterns and not encoded in the DNA.  On a smaller scale, prion proteins, which have two stable conformations, can pass their conformation onto the next generation without the help of any DNA.  He now wonders whether these phenomena pervade all of biology, such that all sorts of traits can be inherited without being encoded in DNA.

As a pilot project, Daedalus is working to create a new organism that has the same genome as wild-type yeast, but wildly different properties.  Just as the Bible can be interpreted in many different ways, and some elaborate coding schemes can be used to find hidden messages in the text, so too will DREADCO biologists attempt to reinterpret the genome.  With this new genetic code in place, different proteins will be produced, including the very machinery needed to produce the new interpretation in the first place.  To reach this goal, Daedalus plans to create all sorts of exotic variations on components of the cell's machinery from many different species.  He will inject these molecules into his experimental yeast, then look several generations down the line to see if any of them have managed to get themselves replicated.

At the same time, Daedalus has concocted another strategy for non-DNA "genetic" engineering.  He recalls that cells are basically huge networks of DNA genes and proteins that can turn each other on and off.  He thinks of these binary on-off patterns as a sort of "software," running on the cell's "hardware."  Furthermore, the "software" can be inherited.  Witness, for instance, that a genetic mutation, inherited from your mother, can produce different effects from the same mutation, inherited from your father, simply because the expression patterns of these genes can be different.

Daedalus suspects that these gene expression patterns can actually store useful information and even computational algorithms.  Rather than mutate DNA every time some evolutionary change is needed, Daedalus muses, wouldn't it be easier to simply flip some switches in a general-purpose circuit?

So, asks Daedalus, why don't we download new software into these yeast!  DREADCO engineers will be hard at work, poring over circuit diagrams of the yeast cell's machinery, trying to find wildly different stable states.  To complement this analysis, DREADCO biologists will be flipping protein conformations and changing gene expression patterns, trying to drive the cell to perform bizarre new behaviors.

Once these techniques are perfected, applications will abound.  Scientists will have a whole new set of tools for engineering features into cells.  Doctors will drop their DNA gene therapy experiments and rush to try the more fashionable non-DNA gene therapy techniques.

F. Edward Boas
(The Daedalus character is borrowed from David Jones' weekly Nature column)

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