Expression and Purification of Recombinant Histones and Nucleosome Reconstitution -- Preparation and Analysis of Positioned Nucleosomes -- Site-Directed Chemical Probing of Histone-DNA Interactions -- Base-Pair Resolution Mapping of Nucleosomes In Vitro -- Equilibrium and Dynamic Nucleosome Stability -- Nucleosome Structure and Dynamics -- Analysis of Linker Histone Binding to Mono- and Dinucleosomes -- Quantitative Analysis of Chromatin Higher-Order Organization Using Agarose Gel Electrophoresis -- Analytical Ultracentrifugation of Chromatin -- Analysis of Chromatin by Scanning Force Microscopy -- In Vivo Mapping of Nucleosomes Using Psoralen-DNA Crosslinking and Primer Extension -- Preparation of Chromatin Assembly Extracts from Xenopus Oocytes -- Preparation of Chromatin Assembly Extracts from Preblastoderm Drosophila Embryos -- A Solid-Phase Approach for the Analysis of Reconstituted Chromatin -- Reconstitution and Analysis of Hyperacetylated Chromatin -- Assembly of Mitotic Chromosomes in Xenopus Egg Extract -- Nucleotide Excision Repair Coupled to Chromatin Assembly -- Photolyase -- Transcriptional and Structural Analyses of Isolated SV40 Chromatin -- In Vitro Replication of Chromatin Templates -- Analysis of HMG-14/-17-Containing Chromatin -- Identification and Analysis of Native Nucleosomal Histone Acetyltransferase Complexes -- Analysis of Nucleosome Disruption by ATP-Driven Chromatin Remodeling Complexes -- Nucleosome Remodeling Factor NURF and In Vitro Transcription of Chromatin -- An SDS-PAGE-Based Enzyme Activity Assay for the Detection and Identification of Histone Acetyltransferases -- Analysis of DNaseI Hypersensitive Sites in Chromatin by Cleavage in Permeabilized Cells -- Mapping of Nucleosome Positions in Yeast -- Analysis of DNA Topology in Yeast Chromatin -- DNA Methyltransferases as Probes for Chromatin Structure in Yeast -- Restriction Nucleases as Probes for Chromatin Structure -- Genomic Footprinting Using Nucleases -- In Situ Analysis of Chromatin Proteins During Development and Cell Differentiation Using Flow Cytometry -- Mapping DNA Target Sites of Chromatin Proteins In Vivo by Formaldehyde Crosslinking -- Mapping DNA Interaction Sites of Chromosomal Proteins -- UV Laser Footprinting and Protein-DNA Crosslinking -- An In Vivo UV Crosslinking Assay That Detects DNA Binding by Sequence-Specific Transcription Factors.

More than 40 years after the discovery of the nucleosome as the fun- mental unit of chromatin, the multifaceted problem of how variations in ch- matin structure affect the activity of the eukaryotic genome has not been solved. However, during the past few years research on chromatin structure and fu- tion has gained considerable momentum, and impressive progress has been made at the level of concept development as well as filling in crucial detail. The structure of the nucleosome has been visualized at unprecedented reso- tion. Powerful multisubunit enzymes have been identified that alter histone/ DNA interactions in ways that expose regulatory sequences to factors initi- ing and regulating such nuclear processes as transcription. Though the imp- tance of posttranslational modifications of histones, notably their acetylation, has long been known, the finding that a number of bona fide regulators increase transcription by acetylating nucleosomes has lent new support to the old idea that the process of gene regulation is intimately related to the nature of the chromatin environment. A wealth of nonhistone proteins contribute to a continuum of structures with distinct biochemical properties and varying degrees of DNA condensation. Perhaps the most important conclusion from a large number of studies is a fresh appreciation of the dynamic nature of chromatin structure, the built-in flexibility providing the basis for regulation.