Chiral mesophases of DNA

In the hexagonal columnar phase of chiral polymers a bias towards cholester ic twist competes with braiding along an average direction. When the chiral ity is strong, topological defects proliferate, leading to either a tilt gr ain boundary phase or a new "moire state" with twisted bond order. This moi re phase can melt leading to a new phase: the chiral hexatic. I will discus s some recent experimental results from the NTH on DNA liquid crystals in t he context of these theories. (C) 2000 Elsevier Science Ltd. All rights res erved.