Yes! That wasn't the exact experiment that I was remembering, but it uses the same principles. I remember being blow away when I read about it.
This example is actually more interesting because they've designed a specific circuit to test for target genes.
And Yes, I'm fairly certain you're right about the base-4 elements of DNA. So not binary, but quaternary.
A small question:
Although this is not really needed in anything i am thinking of:
-Would a system which uses 4 distinct symbols (ie a quaternary sustem) be realistically as efficient as a system that uses two, for the purpose of computers?
I ask this because unlike a system with 2 symbols, the system of 4 symbols does not seem to contain 2 as any major part of it (the system of two symbols has to be assumed to already include the square root of two, since it contains 2 as its numeral edge as well as a symbol inside it, much like our system of 9 digits (1 to 9, 0 is not a digit exactly) contains 9 as its edge, but also has a middle point (5). A system of 4 symbols neither contains 2 as its edge, nor does it have a middle point being an integer. This seems to me to be not really computable by anything outside of that system (eg our dna). Thus (if my assumption is closer to being correct than not) it would follow that we cannot effectively use it as part of computers, since the square root of 2 would not be there, and neither would a border between the digits. 2 is, of course, not just any number, but one of huge importance (one need only have a peripheral view of how many important equations set 2 as either their base, power, or other factors of note in them), like 1, 0, and in our own system also 5 and 9(which includes 3).
2 would be, in a system of 4 symbols, not a border of all symbols, but the sum of any parts of equal numbers of digits in that system, and on the other hand there would only be the following such parts (in the case that the same digits can be used in all first connections between them, ie the first connections are independent of the next ones: 1,2 and 1,3 and 1,4 and 2,3 and 2,4 and 3,4. In the case that the first connections are not independent of the first ones, the used up in pairs symbols may even be used up alltogether in any such pairing: 1,2 and 3,4. There is also a middle status to that, and a number of other arrangements like using the same symbol in a pair of itself, while keeping the second part of the pair seperate from the first. Still they are of a different number and manner than either the binary system, or our 9-digit system). So i am not at all sure if the implications of using that system are mapped out to a degree that moving on from a binary one to it (or even translating the 9-digit system we have since ancient times to it) would be beneficial, even in the longer run.
That dna, obviously, in some manner computes itself in a sort of system of 4 symbols, is great reason to think it is a highly efficient system. Dna is not a human being though. Like we cannot compute how much blood exactly needs to be sent by our body to an organ of it so as to be optimaly beneficial to that, whereas the system of the body can, i have to guess we can neither compute more efficiently with a 4-symbol system than we can now.