"Greg Egan - Distress (2)" - читать интересную книгу автора (Egan Greg)

I went back and intercut some microscope footage of the tailored algae and bacteria inhabiting his
blood and digestive tract, then a shot of the tire dump map, which he'd displayed for me on his
notepad. I played with an animation I'd been preparing, a schematic of his personal carbon,
oxygen, and energy cycles, but I wasn't yet sure where it belonged.
I'd prompted him: "So you're immune to famine and mass extinctions -but what about viruses? What
about biological warfare or some accidental plague?" I cut my words out; they were redundant, and
I preferred to intrude as little as possible. The change of topic was a bit of a non sequitur as
things stood, though, so I synthesized a shot of Landers saying, "As well as using symbionts,"
computed to merge seamlessly with his actual words, "I'm gradually replacing those cell lines in
my body which have the greatest potential for viral infection. Viruses are made of DNA or RNA;
they share the same basic chemistry as every other organism on the planet. That's why they can
hijack human cells in order to reproduce. But DNA and RNA can be manufactured with totally novel
chemistry-with non-standard base pairs to take the place of the normal ones. A new alphabet for
the genetic code: instead of guanine with cytosine, adenine with thymine-instead ofG with C, A
with ├Т-you can have X with Y,W with Z."
I changed his words after "thymine" to: "-you can use four alternative molecules which don't occur
in nature at all." The sense was the
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same, and it made the point more clearly. But when I replayed the scene, it didn't ring true, so
I reverted to the original.
Every journalist paraphrased vis subjects; if I'd flatly refused to employ the technique, I
wouldn't be working. The trick was to do it honestly- which was about as difficult as imposing the
same criterion on the editing process as a whole.
I cut in some stock molecular graphics of ordinary DNA, showing every atom in the paired bases
which bridged the strands of the helix, and I color-coded and labeled one example of each base.
Landers had refused to specify exactly which non-standard bases he was using, but I'd found plenty
of possibilities in the literature. I had the graphics software substitute four plausible new
bases for the old ones in the helix, and repeated the slow zoom-in and rotation of the first shot
with this hypothetical stretch of Landers-DNA. Then I cut back to his talking head.
"A simple base-for-base substitution in the DNA isn't enough, of course. Cells need some brand new
enzymes to synthesize the new bases-and most of the proteins which interact with DNA and RNA need
to be adapted to the change, so the genes for those proteins need to be translated, not just
rewritten in the new alphabet." I improvised some graphics illustrating the point, stealing an
example of a certain nuclear binding protein from one of the journal articles I'd read-but
redrawing the molecules in a different style, to avoid copyright violation. "We haven't yet been
able to deal with every single human gene which needs translation, but we've made some specific
cell lines which work fine with mini-chromosomes containing only the genes they need.
"Sixty percent of the stem cells in my bone marrow and thymus have been replaced with versions
using neo-DNA. Stem cells give rise to blood cells, including the cells of the immune system. I
had to switch my immune system back into an immature state, temporarily, to make the transition
work smoothly-I had to go through some of the childhood clonal deletion phases all over again, to
weed out anything which might have caused an autoimmune response-but basically, I'm now able to
shoot up pure HIV, and laugh about it."


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"But there's a perfectly good vaccine-"
"Of course." I cut my own words out, and made Landers say: "Of course, there's a vaccine for