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Nucleolus

About: Nucleolus is a research topic. Over the lifetime, 5873 publications have been published within this topic receiving 232435 citations. The topic is also known as: GO:0005730 & cell nucleolus.


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Journal ArticleDOI
B. Helpap1
TL;DR: It is suggested that careful analysis of the number and localization of nucleoli can be helpful in theAnalysis of the differential diagnosis between carcinoma and atypical hyperplasia of the prostate, which can be difficult in histopathological and cytopathological material.
Abstract: Specimens of prostate obtained for histopathological and cytological examination by urethral resection and 'punch' biopsies showing carcinoma, atypical and typical hyperplasia were re-examined with regard to the number, size and localization of nucleoli. With increasing degrees of malignancy the number and size of the nucleoli increased and the position of the nucleolus shifted to the periphery of the nucleus. In the cells in typical and slightly atypical prostatic hyperplasia there were few nucleoli which were localized to the centre of the nucleus. In moderately atypical hyperplasia there were intermediate locations, while in severe atypical hyperplasia and 'borderline' malignant cases there was a distinct shift towards the periphery of the nucleus as well as an increase in the number of nucleoli in each nucleus. It is suggested that careful analysis of the number and localization of nucleoli can be helpful in the analysis of the differential diagnosis between carcinoma and atypical hyperplasia of the prostate, which can be difficult in histopathological and cytopathological material.

71 citations

Journal ArticleDOI
TL;DR: A possible mechanism for tRNA gene-mediated silencing is suggested in which subnuclear localization of tRNA genes antagonizes transcription of nearby genes by pol II.
Abstract: In the budding yeast, Saccharomyces cerevisiae, actively transcribed tRNA genes can negatively regulate adjacent RNA polymerase II (pol II)-transcribed promoters. This tRNA gene-mediated silencing is independent of the orientation of the tRNA gene and does not require direct, steric interference with the binding of either upstream pol II factors or the pol II holoenzyme. A mutant was isolated in which this form of silencing is suppressed. The responsible point mutation affects expression of the Cbf5 protein, a small nucleolar ribonucleoprotein protein required for correct processing of rRNA. Because some early steps in the S. cerevisiae pre-tRNA biosynthetic pathway are nucleolar, we examined whether the CBF5 mutation might affect this localization. Nucleoli were slightly fragmented, and the pre-tRNAs went from their normal, mostly nucleolar location to being dispersed in the nucleoplasm. A possible mechanism for tRNA gene-mediated silencing is suggested in which subnuclear localization of tRNA genes antagonizes transcription of nearby genes by pol II.

71 citations

Journal Article
TL;DR: Fusion proteins consisting of maltose binding protein (MBP) and nucleolin are constructed and nuclear targetting of MBP by the bipartite nuclear localization signal of nucleolin became significantly more efficient after addition of either CK2 sites or cdc2 sites to the MBP-NLS construct.

71 citations

Journal ArticleDOI
TL;DR: Mouse-human hybrid cells were used to study the ability of simian virus 40 to regulate the expression of rRNA genes in vivo, and results indicate that simianirus 40 infection can induce theexpression of otherwise silent r RNA genes.
Abstract: Mouse-human hybrid cells were used to study the ability of simian virus 40 to regulate the expression of rRNA genes in vivo. In these hybrid cells, only the rRNA genes of the dominant species are expressed; the genes for the rRNA of the recessive species are silent. Simian virus 40 infection of these hybrids led to the production of two distinct 28S rRNA species as analyzed by agarose/2.4% polyacrylamide gel electrophoresis. These species were identified as human and mouse rRNAs. This result was confirmed by histochemical studies which indicated that the nucleolus organizer regions of both mouse and human chromosomes were actively synthesizing rRNA in the virus-infected hybrid cells. These results indicate that simian virus 40 infection can induce the expression of otherwise silent rRNA genes.

71 citations

Journal ArticleDOI
TL;DR: Genetic and biochemical analyses demonstrated that ELENA1 can dissociate the FIB2/MED19a complex and release Fib2 from PR1 promoter to enhance PR1 expression, uncovering an additional layer of complexity in the transcriptional regulation of plant immune responsive genes by long noncoding RNA.
Abstract: Plant immune response is initiated upon the recognition of pathogen-associated molecular patterns such as elf18. Previously, we identified an Arabidopsis ELF18-INDUCED LONG NONCODING RNA 1 (ELENA1), as a positive transcriptional regulator of immune responsive genes. ELENA1 associated with Mediator subunit 19a (MED19a) to enhance enrichment of the complex on PATHOGENESIS-RELATED GENE 1 (PR1) promoter. In vitro and in vivo RNA-protein interaction experiments showed that ELENA1 can also interact with FIBRILLARIN 2 (FIB2). Co-immunoprecipitation and bimolecular fluorescence complementation assay showed that FIB2 directly interacts with MED19a in nucleoplasm and nucleolus. Analysis of fib2 mutant showed that FIB2 functions as a negative transcriptional regulator for immune responsive genes, including PR1. Genetic and biochemical analyses demonstrated that ELENA1 can dissociate the FIB2/MED19a complex and release FIB2 from PR1 promoter to enhance PR1 expression. ELENA1 increases PR1 expression by evicting the repressor (FIB2) from the activator (MED19a). Our findings uncover an additional layer of complexity in the transcriptional regulation of plant immune responsive genes by long noncoding RNA.

71 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023145
2022209
2021143
2020125
2019139
2018121