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Reaching for the off switch in nucleolar dominance.
Craig S Pikaard1,2,3, Chinmayi Chandrasekhara1,2, Anastasia McKinlay1,2,3
1Department of Biology, Indiana University, Bloomington, Indiana, USA.
The Plant Journal : for Cell and Molecular Biology
|May 25, 2023
Summary
Nucleolar dominance, a phenomenon of selective rRNA gene silencing, occurs in hybrids and pure species. Recent studies reveal silencing depends on the nucleolus organizer region (NOR) location, not gene sequence.
Area of Science:
- Genetics
- Cell Biology
- Epigenetics
Background:
- Nucleolus organizer regions (NORs) are chromosomal sites containing ribosomal RNA (rRNA) genes.
- Ribosome biogenesis occurs in the nucleolus, a sub-nuclear structure.
- Nucleolar dominance describes differential rRNA gene transcription in hybrids.
Purpose of the Study:
- To review the historical and recent understanding of nucleolar dominance.
- To explore the epigenetic mechanisms underlying selective rRNA gene silencing.
- To discuss the scale shift in studying nucleolar dominance from genes to chromosomes.
Main Methods:
- Cytogenetic observations of NOR morphology.
- Analysis of rRNA gene transcription differences.
- Investigation of repressive chromatin modifications.
Main Results:
- Nucleolar dominance involves selective rRNA gene silencing.
- Silencing is mediated by epigenetic mechanisms and repressive chromatin.
- Gene silencing is NOR-dependent, not sequence-dependent.
Conclusions:
- Nucleolar dominance is a widespread phenomenon involving epigenetic regulation.
- Understanding the "off switch" for rRNA genes requires a focus on NORs and chromosomes.
- Further research is needed for a complete genetic and biochemical understanding.
Keywords:
Arabidopsis suecicaArabidopsis thalianaBrassica allopolyploidsDNA methylationchromatinhistone modificationnucleolusnucleolus organizer regionrRNA generibosomal RNAtranscriptional silencingMore Related Videos
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