Clinorotation influences rDNA and NopA100 localization in nucleoli

Autor: Francisco Javier Medina, Fernando González-Camacho, Elizabeth Kordyum, V. Rodríguez-Vilariño, Sobol Ma
Rok vydání: 2005
Předmět:
Zdroj: Digital.CSIC. Repositorio Institucional del CSIC
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ISSN: 0273-1177
DOI: 10.1016/j.asr.2005.05.072
Popis: The nucleolus is the transcription site of rRNA genes as well as the site of processing and initial packaging of their transcripts. The plant nucleolin homologue NopA100 is involved in the regulation of r-chromatin condensation/expansion and rDNA transcription as well as in rRNA processing. We have investigated with immunogold electron microscopy the location of nucleolar DNA and NopA100 in cress root meristematic cells grown under slow horizontal clinorotation, reproducing an important feature of microgravity, namely the absence of an orienting action of a gravity vector, compared to control conditions. We demonstrate redistribution of both rDNA and NopA100 in nucleolar subcomponents induced by clinorotation. Ribosomal DNA concentrated predominantly in fibrillar centers in the form of condensed r-chromatin inclusions and internal non condensed fibrils, redistributing from the dense fibrillar component and the transition zone between fibrillar centers and the dense fibrillar component, recognized as the loci of rDNA transcription. The content of NopA100 was much higher in the inner space of fibrillar centers and reduced in the dense fibrillar component as compared to the control. Based on these data, an effect of slow horizontal clinorotation in lowering the level of rDNA transcription as well as rRNA processing is suggested. © 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.
This work was supported by a Grant of INTAS Ref. No. YSF 2001/2-144, a Grant from the National Space Agency of Ukraine Ref. No. 2-10/1-00, and Grants from the Spanish “Plan Nacional de Investigación Científica y Desarrollo Tecnológico” Refs. Nos. ESP2001-4522-PE and ESP2003-09475-C02-02
Databáze: OpenAIRE
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