title: A combined ultrastructural approach to the study of nuclear matrix thermal stabilization.
abstract: Using mouse erythroleukaemia cells and different ultrastructural techniques, the morphology was investigated of the nuclear matrix obtained after incubation at 37 degrees C of isolated nuclei. If purified nuclei were heated for 45 min at 37 degrees C, the final matrix exhibited well-recognizable nucleolar remnants, an inner network and a peripheral lamina. Without such incubation only the peripheral lamina was seen surrounding homogeneous, finely granular material. Similar results were obtained with both araldite-embedded and freeze-fractured nuclear matrices, although in the latter case the loose granular material was not evident. Observations of araldite-embedded, heat-treated nuclei revealed clumping of heterochromatin in small, very electron-dense masses with large interchromatin spaces. These ultrastructural aspects were even more striking in freeze-fractured nuclei. Cytochemical matrix analysis by osmium-amine staining for nucleic acids and DNase-gold labelling for DNA localization demonstrated that also matrix residual nucleic acids, mostly RNA, are stabilized by heat exposure of isolated nuclei. The results demonstrate that the morphology of heat-stabilized nuclear matrix is not artefactually affected during the preparation for conventional electron microscopy and suggest a possible involvement of nucleic acids in the heat-induced stabilization of the nuclear matrix.
authors.affiliation: Istituto di Anatomia Umana Normale, Università di Bologna, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Falcieri
authors.forename: P
authors.initials: P
authors.lastname: Gobbi
authors.forename: P
authors.initials: P
authors.lastname: Sabatelli
authors.forename: S
authors.initials: S
authors.lastname: Santi
authors.forename: F
authors.initials: F
authors.lastname: Farabegoli
authors.forename: R
authors.initials: R
authors.lastname: Rana
authors.forename: A
authors.initials: A
authors.lastname: Cataldi
authors.forename: N M
authors.initials: NM
authors.lastname: Maraldi
authors.forename: A M
authors.initials: AM
authors.lastname: Martelli
mesh_terms: D000818:Animals; D004273:DNA, Neoplasm / Q000378:metabolism; D003851:Deoxyribonucleases / Q000378:metabolism; D005614:Freeze Fracturing; D005622:Friend murine leukemia virus; D006651:Histocytochemistry; D004915:Leukemia, Erythroblastic, Acute / Q000473:pathology*; D051379:Mice; D015530:Nuclear Matrix / Q000648:ultrastructure*; D016613:Plastic Embedding; D012334:RNA, Neoplasm / Q000378:metabolism; D013194:Staining and Labeling; D014407:Tumor Cells, Cultured
chemical_list: D004273:DNA, Neoplasm; D012334:RNA, Neoplasm; D003851:Deoxyribonucleases