At the Huffington Post's science section, University of Chicago microbiologist James Shapiro says that even with everything that's known about DNA, there are still messages in DNA that researchers don't know how to interpret. "Among the most mysterious features of evolving genomes are stretches of DNA that carry two or more kinds of information in a single sequence," Shapiro says. "This multiplicity of coincident messages raises a number of intriguing questions." For example, he adds, how does it happen that multiple messages are inscribed in a single sequence?
Shapiro's personal "intellectual headache" is the "shufflon," he says — a structure in some bacteria that the organisms use to diversity extracellular proteins, which is "advantageous in extending the range of specific cell-cell attachments for transfer of DNA and other macromolecules."
How this system evolved in bacteria is a mystery, just as researchers don't fully understand how mammalian dual-coding regions evolved simultaneously to encode functional protein segments. "At a time when we pride ourselves for being able to read DNA sequences with increasing speed, it is salutary to keep in mind that we are still far from knowing how to interpret the complex overlapping meanings contained in the genomic texts we store in our databases," Shapiro says. "DNA, like poetry, often has to be read in several ways."