Chiral Mesophases of DNA

In the hexagonal columnar phase of chiral polymers a bias towards cholesteric twist competes with braiding along an average direction. When the chirality is strong, topological defects proliferate, leading to either a tilt grain boundary phase or a new ``moire state'' with twisted bond order. This moire phase can melt leading to a new phase: the chiral hexatic. I will discuss some recent experimental results from the NIH on DNA liquid crystals in the context of these theories.