Regulation of Ribosomal RNA Accumulation by Auxin in Artichoke Tissue

Melanson, Dara L.; Ingle, John

doi:10.1104/pp.62.5.761

Cited by 15 publications

(8 citation statements)

References 24 publications

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“…Thus, in agreement with other plants in which the 2.8 to 3.4 megadalton component is apparently missing (e.g. 15,17,18), the processing of cytoplasmic rRNA involves a primary transcript of2.5 megadalton and intermediates of 1.4, 1.0, and 0.75 megadalton (17).…”

Section: Resultssupporting

confidence: 52%

“…the same prerRNA half-life) in dark-grown and irradiated tissue. It is interesting to note that, in a related study dealing with the influence of THIEN ANE auxin on the labeling kinetics of precursor and mature RNAs in artichoke tissue (15), a discrepancy between the hormone-mediated increases of pre-rRNA pool size and the accumulation rate of mature rRNAs has been found. This result has been taken as evidence that the switching on of rRNA accumulation in this tissue is in part due to an increase in transcription of pre-rRNA and in part due to posttranscriptional control involving changes in the kinetics of processing.…”

Section: Resultsmentioning

confidence: 99%

“…The details of the molecular mechanism of these photomorphogenetic responses are still unclear. For instance, since rRNA can be subject to turnover (15,26), the measured increase of accumulation could be due either to an enhancement of the formation or a slowing down of the degradation of rRNA. The occurrence of degradation of cytoplasmic rRNA is clearly shown in older mustard cotyledons (>60 h after sowing), but might be masked by rRNA synthesis before this time (23).…”

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confidence: 99%

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Control by Phytochrome of Cytoplasmic Precursor rRNA Synthesis in the Cotyledons of Mustard Seedlings

Thien

Schöpfer²

1982

Plant Physiol.

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The influence of phytochrome (high irradiance reaction operationaly, continuous far red light) on the incorporation of 3HIurdlne into the cytoplasmic 2.5 megadalton precursor rRNA in the cotyledons of mustard (Sinapis alba L.) seedlings has been investigated. After irradiatig 36-hourold etiolated seedlings with 12 hours of far red light, the rate of inorporation is stimulated about 2-fold, leading to 50% labeling of the precursor rRNA pool about 15 minutes after the tracer has reached the nucleotide precursor pooL In the dark control, there is a sipificantly smaler pool of precursor rRNA which is half-saturated with label only after about 27 minutes. Since neither the specific radioactivity of the UT pool nor the processing of the precursor rRNA demonstrate a corresponding ightdependent change, it is concluded that phytochrome mediates an increase of the transcription of the rRNA genes. Tnis gene activation acconts for the increased accumulation of mature cytoplasmic rRNA during the course of photomorphogenesis of the cotyledons.

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Section: Resultssupporting

confidence: 52%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Control by Phytochrome of Cytoplasmic Precursor rRNA Synthesis in the Cotyledons of Mustard Seedlings

Thien

Schöpfer²

1982

Plant Physiol.

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“…All rights reserved. Key, 1983), the accumulation of rRNA (Melanson, 1978), and the phosphorylation of certain ribosomal proteins (Pérez et al, 1987(Pérez et al, , 1990. Auxin also caused an increase in the coordinated expression of ribosomal proteins (Gantt and Key, 1985;Gao et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

Association of Plant p40 Protein with Ribosomes Is Enhanced When Polyribosomes Form during Periods of Active Tissue Growth

et al. 1996

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Missouri 6521 1 (T.I.B.) p40s are acidic proteins of eukaryotic cells occurring either free in the cytoplasm or in association with ribosomes, the latter occurring in both monosomes and polysomes. p40s may play a role in the regulation of protein synthesis, although the exact mechanism is not known. Leaves of all 1 0 plant species examined here, including both monocots and dicots, contained proteins detected on immunoblots with Arabidopsis thaliana p40 antiserum. The number and apparent size of the protein bands were variable even among closely related species. Abundance of p40 relative to ribosomal content during soybean (Glycine max L.) seed germination and during seed and leaf development was examined. p40 abundance correlated with periods of active tissue growth and high polysome content. l h e plant growth regulator indole acetic acid caused an increase in polysome formation in etiolated pea (Pisum safivum L.) plants and a concomitant recruitment of p40 into polysomes. Subcellular localization at the microscopy leve1 indicated that the pattern of p40 staining is very similar to that for RNA, except that p40 is excluded from the nucleus. These data suggest that p40 is an accessory protein of the ribosome that might play a role in plant growth and development.A recently recognized class of acidic proteins that associate with ribosomes is called p40. These proteins are conserved among eukaryotes as distantly related as mammals (Makrides et al

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“…Since mature rRNAs (1 8S and 25S or 0.7 and 1.3 x 106 D, respectively) are initially transcribed as a large precursor molecule of about 2.8 x 105 D in some plants (8,17,25) and about 2.3 x 106 in others (6, 28) including soybean (15), the rate of processing of these large transcripts could be involved in establishing the rate of accumulation of new ribosomes. Melanson and Ingle (23) in fact have reported that precursor processing, including a large increase in the rate of processing of the 1.4 x 106 precursor into the mature 1.3 x 106 (25S) rRNA, accounts for a part of the auxin-enhanced synthesis and accumulaton of ribosomes in artichoke tissue. The availability of ribosomal proteins may also play a role in the rate of processing of pre-rRNA and/or accumulation of ribosomes.…”

Section: Discussionmentioning

confidence: 99%

Fractionation of Nucleoli from Auxin-Treated Soybean Hypocotyl into Nucleolar Chromatin and Preribosomal Particles

Chen

Huang²,

Lin³

et al. 1983

Plant Physiol.

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ABSTRACrNucleoli from auxin-treated tissues (Glycine max L. var Wayne or Kaoshiung No. 3) were isolated and purified by Percoll density gradient centrifugation. There was a 2.1-fold increase in RNA and a 2.8fold increase in protein after a 24-h auxin treatment per unit nucleolar DNA. More than 150 acid-soluble protein spots were associated with the auxintreated nucleoli on two dimensional (2-D) gel electropherograms.Nucleoli from auxin-treated tissue were fractionated by suspension in 20 millimolar dithiothreitol at room temperature for 20 minutes into two distinct fractions referred to as the nucleolar chromatin and preribosomal particle fractions. The DNA:RNA:protein ratio ofthe chromatin fraction was 1:2.5:14. Most of RNA polymerase 1 activity and nucleolar DNA recovered in this fraction. The acid-soluble proteins in the chromatin were resolved into 32 protein spots on 2-D gel electropherogram. The most abundant spots were identified as histones.The nucleolar preribosomal particle fraction had a DNA:RNA:protein ratio of 1:24:102 and contained only trace amounts of RNA polymerase 1 activity and only 10 per cent of the nucleolar DNA. Acid-soluble proteins associated with these particles were resolved into 78 protein spots; 72 of these (acid-soluble) protein spots corresponded in 2-D gel electrophoresis to 80S cytoplasmic ribosomal proteins. Some 15 protein spots found in 80S ribosomal proteins were absent in the preribosomal particles. It seems reasonable, based on these data, that the enlargement of nucleoli after auxin treatment is primarily due to the large increase in ribosomal proteins and rRNA which accumulate and assemble in the nucleoli in the form of preribosomal particles.A substantial body of literature has established that the synthesis and processing of pre-rRNA occurs in the nucleolus of eukaryotic organisms (2,22,29,31). The nucleolar organizer region (15) contains several hundred to several thousand copies of rRNA genes which are associated with proteins in the form of nucleolar chromatin. During the transcription of pre-rRNA, several ribosomal proteins become associated with the nascent RNA; this leads to further processing and packaging of the prerRNA in the nucleolus to form ribonucleoprotein complexes termed preribosomal particles or preribosomes (29).The nucleolar volume as a fraction of total nuclear volume varies considerably as tissues undergo altered rates of ribosome production. For example, partial hepatectomy or injection of thioacetamide into rats results in an increase in relative nucleolar

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Regulation of Ribosomal RNA Accumulation by Auxin in Artichoke Tissue

Cited by 15 publications

References 24 publications

Control by Phytochrome of Cytoplasmic Precursor rRNA Synthesis in the Cotyledons of Mustard Seedlings

Control by Phytochrome of Cytoplasmic Precursor rRNA Synthesis in the Cotyledons of Mustard Seedlings

Association of Plant p40 Protein with Ribosomes Is Enhanced When Polyribosomes Form during Periods of Active Tissue Growth

Fractionation of Nucleoli from Auxin-Treated Soybean Hypocotyl into Nucleolar Chromatin and Preribosomal Particles

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