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Localization and processing from a polycistronic precursor of novel snoRNAs in maize
P J Shaw1, A F Beven, D J Leader
1John Innes Centre, Colney, Norwich NR4 7UH, UK. peter.shaw@bbsrc.ac.uk
Journal of Cell Science
|July 17, 1998
Summary
Novel small nucleolar RNAs (snoRNAs) in maize, including box C/D and box H/ACA types, exhibit distinct nucleolar localizations. Their precursor is imported into the nucleolus, involving coiled bodies for processing.
Area of Science:
- Molecular Biology
- Plant Genetics
- Nucleolar Function
Background:
- Maize U14 snoRNA genes are clustered with novel snoRNAs, transcribed polycistronically, and processed independently of splicing.
- These clusters contain box C/D snoRNAs (rRNA O-ribose methylation) and the first plant box H/ACA snoRNA (rRNA pseudo-uridylation).
Purpose of the Study:
- To investigate the sub-nucleolar localization of four novel snoRNAs within U14-containing gene clusters in maize.
- To determine the localization of the polycistronic precursor snoRNA and infer its import and processing pathway.
Main Methods:
- In situ hybridization using probes for novel snoRNAs and precursor snoRNA intergenic spacer regions.
- Analysis of sub-nucleolar localization patterns within the maize nucleolus.
Main Results:
- Four novel snoRNAs (snoR1, snoR2, snoR3, U49) display distinct sub-nucleolar localizations.
- snoR2 (box H/ACA) and snoR3 (box C/D) colocalize with rDNA transcription sites.
- snoR1 (box C/D) localizes to a different nucleolar region, potentially involved in later pre-rRNA processing.
- The polycistronic precursor snoRNA localizes to the dense fibrillar component and coiled bodies.
Conclusions:
- Novel snoRNAs exhibit specific localization patterns within the nucleolus, suggesting distinct roles in rRNA biogenesis.
- The polycistronic precursor snoRNA is imported into the nucleolus and processed, with coiled bodies playing a role in this pathway.