Castles in the air - they are so easy to take refuge in. And so easy to build, too.

आम्हां घरी धन शब्दांचीच रत्नें | शब्दांचीच शस्त्रें यत्न करुं ||
शब्द चि आमुच्या जीवांचे जीवन | शब्दें वांटूं धन जनलोकां ||
तुका म्हणे पाहा शब्द चि हा देव | शब्द चि गौरव पूजा करुं ||
- abhang of Tukaram Wolhoba Ambile of Dehu

There's No Freedom Like That of a Child's Imagination

கடலுக்கு உண்டு கற்பனைக்கு இல்லை கட்டுப்பாடு

Wednesday, May 26, 2010

Artificial Life: Not Yet Frankenstein

When I was a teenager, I once drew a picture of a rather outlandish fish (I think it has disappeared somewhere), on the idea that it will be created by geneticists at some point in time. The first baby step (as the iconic Craig Venter himself says) has now been taken, but it's nowhere near Mary Shelley's Frankenstein.

Dr. Venter and his people have announced the creation of the first Mycoplasma mycoides cell whose genome comprises entirely of DNA made in the lab. It isn't the first, since in 2007 they made a virus. But since viruses are in the twilight zone between life and non-life, I suppose that doesn't count.

Now this isn't completely artificial. The genome is 100% natural, not a single deliberately modified base. Large chunks of DNA were cut out, cloned into yeast, then cut with restriction enzymes and ligated back into a full chromosome. Strip an existing cell of its DNA and inject this new chromosome. Voila, the cell responds to the new chromatin.

What would really be fun were if there were a set of artificial genes, those that created a protein system that did something really newfangled. Catalyze a new kind of reaction altogether. Break up cyanide or something. Then you create an artificial organism which had that new metabolism. Now that would be something new, something evolution didn't think up by itself.

Meanwhile, the mud flies. Questions get raised about the ethics of the things. Bioterrorism? I mean all you need for 'bioterrorism' is to introduce a few petri dishes worth of Vibrio cholerae culture into a city's water supply. Why do you need artificial organisms for that? Here's the good doctor answering that charge and more:-



(Gloat to myself: three years after quitting science, I can still remember the jargon!)

Addendum: I should have added something more about the method. It is fiendishly difficult in the first place. I have tried something infinitely easier than that and failed. (Which is why molecular biology is now a part of my shady past, and not my bright future.) But hats off to these guys. You isolate a whole chromosome without shearing it; cut it by restriction enzymes, run it on a gel and then extract the DNA (if they used an electrophoretic method, that is. They could have used centrifugation; I haven't read their paper.)

Then you clone it into a vector with ligase. God help you there, it is such a painful and low-yielding reaction. Then you transfer that DNA in through the cell membrane of the recipient yeast cells, and hope like mad that it will grow in culture.

After that it boggles me. Isolate the cloned DNA (without shearing), purify it, put it all together with ligase, hope like really, really mad it will form a whole chromosome, and then finally put it into a recipient Mycoplasma. I'm surprised (and grateful) that they're all alive and healthy and not feeling suicidal at the end of the process.

But now can somebody fulfil that dream of mine?

Even more addendum: Here's an article in praise of artificial life, the first I have come across.

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