ELCS in ice: cryo-electron microscopy of nuclear envelope-limited chromatin sheets.
Chromosoma
; 123(3): 303-12, 2014 Jun.
Article
em En
| MEDLINE
| ID: mdl-24570264
ABSTRACT
Nuclear envelope-limited chromatin sheets (ELCS) form during excessive interphase nuclear envelope growth in a variety of cells. ELCS appear as extended sheets within the cytoplasm connecting distant nuclear lobes. Cross-section stained images of ELCS, viewed by transmission electron microscopy, resemble a sandwich of apposed nuclear envelopes separated by â¼30 nm, containing a layer of parallel chromatin fibers. In this study, the ultrastructure of ELCS was compared by three different methods:
(1) aldehyde fixation/dehydration/plastic embedding/sectioning and staining, (2) high-pressure freezing/freeze substitution into plastic/sectioning and staining, and (3) high-pressure freezing/cryo-sectioning/cryo-electron microscopy. ELCS could be clearly visualized by all three methods and, consequently, must exist in vivo and are not fixation artifacts. The â¼30-nm chromatin fibers could only be observed following aldehyde fixation; none were seen in cryo-sections. Electron microscopic tomography tangential views of aldehyde-fixed ELCS suggested an ordering of the separate chromatin fibers adjacent to the nuclear envelope. Possible mechanisms of this chromatin ordering are discussed.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Cromatina
/
Membrana Nuclear
Limite:
Humans
Idioma:
En
Revista:
Chromosoma
Ano de publicação:
2014
Tipo de documento:
Article