spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Martin, M.
Right arrow Articles by Medina, F. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Martin, M.
Right arrow Articles by Medina, F. J.

Journal of Cell Science, Vol 100, Issue 1 99-107, Copyright © 1991 by Company of Biologists

JOURNAL ARTICLES

A Drosophila anti-RNA polymerase II antibody recognizes a plant nucleolar antigen, RNA polymerase I, which is mostly localized in fibrillar centres

M Martin and FJ Medina
Centro de Investigaciones Biologicas (CSIC), Madrid, Spain.

The distribution of nucleolar RNA polymerase in the nucleolus of onion root meristematic cells has been studied by means of an antibody originally raised against Drosophila RNA polymerase II. This antibody recognizes the homologous domains of the large subunit of the enzyme, which are highly conserved throughout evolution in the three classes of eucaryotic RNA polymerases. Given that RNA polymerase I is confined to the nucleolus, and that the onion cell nucleolus lacks digitations of extranucleolar chromatin, we conclude that the nucleolar enzyme localized is RNA polymerase I. A quantitative approach, independent of the existence of borderlines between nucleolar fibrillar centres and the dense fibrillar component, allowed us to show that the enzyme is localized in fibrillar centres and in the transition area between them and the dense fibrillar component, in parallel with the nucleolar DNA. These results, together with previous autoradiographic, cytochemical and immunocytochemical results, in this and other species, lead us to conclude that the activation of rDNA for transcription occurs in the fibrillar centres and pre-rRNA synthesis is expressed at the transition area between fibrillar centres and the dense fibrillar component. Fibrillar centres are connected to each other by extended RNA polymerase-bound DNA fibres, presumably active in transcription. This work provides evidence of the high evolutionary conservation of some domains of the large subunit of RNA polymerases and of the existence of fibrillar centres in the nucleolus of plant cells, totally homologous to those described in mammalian cells.


This article has been cited by other articles:


Home page
 J. Cell Sci.Home page
A Olmedilla, P. Testillano, O Vicente, M Delseny, and M. Risueno
Ultrastructural rRNA localization in plant cell nucleoli. RNA/RNA in situ hybridization, autoradiography and cytochemistry
J. Cell Sci., January 12, 1993; 106(4): 1333 - 1346.
[Abstract] [PDF]


© The Company of Biologists Ltd 1991