[directevolve]

PCR (the chemical reaction) isn’t near optimal, but thermocyclers (the device) are hard to improve on.

For PCR, one of the innovations I’m excited about is the development of PCR that preserves chemical properties of the input DNA, like CG methylation. This is a critical epigenetic mark on cytosines (C DNA bases). When cytosine’s followed by guanine (G base), forming the sequence CG, its complement is also CG. There’s an enzyme called a maintenance methyltransferase that copies CG methylation from the template ssDNA strand to the new reverse strand during DNA replication.

Normally this mark gets diluted into invisibility during PCR, because there’s no maintenance methyltransferase to preserve it as the input DNA is copied. A thermostable maintenance methyltransferase can preserve CG methylation throughout PCR. This is brand new technology that’s just making its way into the scientific marketplace now. It’s the kind of PCR innovation my lab’s excited about.