Arnold G. Reinhold writes:
> If you know the DNA sequences of alphabet letters, you can PCR probe
> for common words or word fragments like "the" or "ing" and avoid
> total sequencing.
That's true. Luckily, there is no such test for random base sequences,
though a pseudorandom sequence would certainly be very visible, but
only if the genome has been totally sequenced (currently, an expensive
and slow enterprise, despite Celera making large headways into
it). Hence the need for steganography, which is further worsened by
significant evolutionary conservation throughout the biological
kingdom. The payload will be not be very high.
> A recent Genetic Engineering News says the price for synthetic DNA is
> dropping from $1 per base to about $0.50 per base. That works out to
> $0.25 per bit. That's about 8 orders of magnitude more expensive than
> PC disk storage.
This only applies to short sequences. If you have to (PCR-) ligate
your sequences from shorter segments as output by the synthesizer
robot, the price will skyrocket. Hey, nobody said it's going to be
cheap, nor fast ;)
The good part is extremely dense storage (i dot can contain far more
than microfilm), and potential for destruction on demand: via
packaging in a container bisected with a breakable membrane, one part
containing the DNA (precipitated, or as solution) and the other a
strongly fragmenting chemical (DNAses probably too slow, something
strongly oxidizing like concentrated perchloric acid should do).
