title: Transitions between in situ and isolated chromatin.
abstract: We show that the mechanism by which chromatin displaying higher-order structure is usually isolated from nuclei involves a transition to an extended nucleosomal arrangement. After being released from nuclei, chromatin must refold in order to produce the typical chromatin fibers observed in solution. For starfish sperm chromatin with a long nucleosome repeat (222 bp), isolated fibers are significantly wider than those in the nucleus, indicating that the refolding process does not regenerate the native higher-order structure. We also propose that for typical eukaryotic nuclei, the concept that the native state of the (inactive) bulk of the genome is a chromatin fiber with defined architecture be reconsidered.
authors.affiliation: Department of Biology, University of Massachusetts, Amherst 01003.
authors.forename: P J
authors.initials: PJ
authors.lastname: Giannasca
authors.forename: R A
authors.initials: RA
authors.lastname: Horowitz
authors.forename: C L
authors.initials: CL
authors.lastname: Woodcock
mesh_terms: D000818:Animals; D002463:Cell Membrane Permeability; D002467:Cell Nucleus / Q000648:ultrastructure; D002843:Chromatin / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism / Q000648:ultrastructure*; D006657:Histones / Q000737:chemistry; D008297:Male; D008836:Micrococcal Nuclease / Q000494:pharmacology; D009685:Nuclear Envelope / Q000378:metabolism; D009707:Nucleosomes / Q000648:ultrastructure; D017510:Protein Folding; D013094:Spermatozoa / Q000648:ultrastructure; D013215:Starfish
chemical_list: D002843:Chromatin; D006657:Histones; D009707:Nucleosomes; D008836:Micrococcal Nuclease