Preparation of chromatin assembly extracts from preblastoderm Drosophila embryos.

A rigorous biochemical analysis of chromatin structure and function requires the assembly of chromatin in vitro. A useful alternative to reconstituting nucleosomal arrays from pure or recombinant histones by salt gradient dialysis is the assembly of more complex chromatin from assembly extracts under physiological conditions. Extracts from preblastoderm embryos have proven to be particularly efficient, due to the presence of large stores of native complexes of histones, histone chaperones and ATP-dependent nucleosome spacing factors. The resulting chromatin is an excellent approximation of physiological chromatin in vivo. This chapter describes the preparation of chromatin assembly extracts and the chromatin assembly reaction.