John F. Marko
Northwestern University
Department of Biochemistry, Molecular Biology, Cell Biology
and Physics and Astronomy

ABSTRACT
I will discuss experiments examining chromatin structure, using novel 
micromechanical approaches. Experiments where chromatin is assembled 
onto single DNAs under precise force control permit study of details of 
nucleosome assembly and disassembly. My group has used this approach to 
measure absolute free energy and kinetic rates for cell-extract-based 
chromatin assembly reactions.  I will also discuss a separate line of 
experiments where individual mitotic amphibian chromosomes are studied 
micromechanically, providing new information about chromatin packing 
and connectivity.  Our experiments indicate that the non-DNA "protein 
scaffold" takes the form of disconnected "chromatin crosslinks", and 
also suggest a role for DNA entanglements in mitotic chromosome 
structure.