There have been many recent theoretical and technical advances in the
sequencing of DNA in ultrathin slab gels. These include recent experim
ental progress in four areas: DNA polymerases; DNA template preparatio
n; the separation and detection of DNA bands; and base-calling algorit
hms. The Zimm-Lumpkin theory of electrophoresis provides a new and imp
roved framework for understanding the operation of sequencing gels.