Effect of cycloheximide on the in vivo and in vitro synthesis of ribosomal RNA in rat liver

Karagyozov, Luchezar; Stoyanova, Bistra B.; Hadjiolov, A.A.

doi:10.1016/0005-2787(80)90082-9

Cited by 22 publications

(5 citation statements)

References 31 publications

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“…To confirm this hypothesis, we carried out a time‐course analysis. The estimated in vivo elongation rate of pre‐rRNA is 1.1 kb min −1 (Karagyozov et al ., 1980), and the length of the pea rDNA transcribed sequence is 6.6 kb (Jorgensen et al ., 1987; Thompson et al ., 1997). Thus, transcription of the primary pre‐rRNA would be expected to take approximately 6 min.…”

Section: Resultsmentioning

confidence: 99%

Single ribosomal transcription units are linear, compacted Christmas trees in plant nucleoli

et al. 2001

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SummaryThe rDNA transcription units are enormous macromolecular structures located in the nucleolus and containing 50±100 RNA polymerases together with the nascent pre-rRNA attached to the rDNA. It has not previously been possible to visualize nucleolar transcription units directly in intact nucleoli, although highly spread preparations in the electron microscope have been imaged as`Christmas trees' 2±3 mm long. Here we determine the relative conformation of individual transcription units in Pisum sativum plant nucleoli using a novel labelling technique. Nascent transcripts were detected by a highly sensitive silver-enhanced 1 nm gold procedure, followed by 3D electron microscopy of entire nucleoli. Individual transcription units are seen as conical, elongated clusters approximately 300 nm in length and 130 nm in width at the thickest end. We further show that there were approximately 300 active ribosomal genes in the nucleoli examined. The underlying chromatin structure of the transcribing rDNA was directly visualized by applying a novel limited extraction procedure to ®xed specimens in order to wash out the proteins and RNA, thus speci®cally revealing DNA strands after uranyl acetate staining. Using this technique, followed by post-embedding in situ hybridization, we observed that the nucleolar rDNA ®bres are not extended but show a coiled, thread-like appearance. Our results show for the ®rst time that native rDNA transcription units are linear, compacted Christmas trees.

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Section: Resultsmentioning

confidence: 99%

Single ribosomal transcription units are linear, compacted Christmas trees in plant nucleoli

et al. 2001

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“…These studies were based on the hypothesis that the maturation of 45S rRNA is modified following alterations in cellular protein synthesis. When protein synthesis is inhibited experimentally in eukaryotic cells, there is a reduction in rRNA processing, but not in its synthesis (Karagyozov et al, 1980; Stoyanova and Dabeva, 1980). Initially, the loss of rRNA processing was ascribed to either loss of a rapid turnover protein involved in maturation or alterations in the intracellular free nucleotide pool (Grummt and Grummt, 1976; Stoyanova and Dabeva, 1980).…”

Section: Discussionmentioning

confidence: 99%

Ribosomal RNA transcriptional activation and processing in hamster rubrospinal motoneurons: Effects of axotomy and testosterone treatment

Storer¹,

Jones²

2003

J of Comparative Neurology

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Rubrospinal motoneurons (RSMN) represent a population of androgen receptor-expressing central motoneurons with limited regenerative potential relative to their peripheral counterparts. A key determinant of regenerative capability lies in the nucleolar reaction of injured neurons. To date, characterization of the nucleolar reaction in injured central motoneurons has not been accomplished. Furthermore, it has been documented that testosterone propionate (TP) augments peripheral motoneuron regeneration through regulation of the nucleolar reaction to injury. In this study, the effects of injury alone, or in conjunction with TP, on the nucleolar response of injured RSMN were examined using in situ hybridization (ISH) techniques. Castrated adult male hamsters were subjected to right spinal cord hemisection at the C7/T1 vertebral level. Half the animals were subcutaneously implanted with one Silastic TP capsule, with the other half sham implanted. ISH for precursor 45S and mature 28S rRNA was accomplished with a (3)H-labeled ribosomal DNA probe specific to the external transcribed spacer region or to the 28S region of the ribosomal gene, respectively. Postoperative times of 2, 6, and 24 hours were selected for examination of precursor 45S rRNA (i.e., rRNA transcriptional activation) levels and 0.25, 2, 4, and 14 days for examination of mature rRNA (i.e., ribosome) levels. Transcriptional activation of the rRNA gene was rapidly and transiently increased in injured RSMN, analogously to previously documented effects of injury on rRNA transcription in peripheral motoneurons, but, in contrast, this did not translate into an increase in mature ribosomes. TP administration failed to affect positively the nucleolar response of injured RSMN at all. From this study, a key component underlying inherent differences in the regenerative capacity of peripheral vs. central motoneurons has been identified, which can be targeted in future experiments designed to enhance the regenerative potential of selective neuronal populations.

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“…The relatively large amounts of TFIC present relative to factor C cast further doubt as to the structural or functional relationship of these factors despite several similarities. At present, there is also no direct evidence for a potential relationship among any of these factors and the short-lived polypeptide that has been implicated in the regulation of rRNA synthesis in vivo [112][113][114][115][116].…”

Section: Down-regulation Of Rdna Transcription By Drugs or Arrest Of mentioning

confidence: 95%

Regulation of ribosomal gene transcription

Jacob

1995

Biochemical Journal

102

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Effect of cycloheximide on the in vivo and in vitro synthesis of ribosomal RNA in rat liver

Cited by 22 publications

References 31 publications

Single ribosomal transcription units are linear, compacted Christmas trees in plant nucleoli

Single ribosomal transcription units are linear, compacted Christmas trees in plant nucleoli

Ribosomal RNA transcriptional activation and processing in hamster rubrospinal motoneurons: Effects of axotomy and testosterone treatment

Regulation of ribosomal gene transcription

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