Transfer RNA and Cell Differentiation

Sueoka, Noboru; Kano-Sueoka, Tamiko

doi:10.1016/s0079-6603(08)60560-7

Cited by 137 publications

(36 citation statements)

References 133 publications

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“…However, the relative tRNA content was estimated by amino acid acceptance. This function is not sensitive to changes in methylation or in isopentenyl content (22). It is possible that the primary critical change concerns only a small cell compartment.…”

Section: C-phenylalaninementioning

confidence: 99%

Action of Kinetin on Cotyledons of Fenugreek

Rijven

Parkash

1971

Plant Physiol.

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Isolated cotyledons of fenugreek (Trigonella foenum graecum L.), which respond rapidly and specifically to the application of cytokinins with stimulated expansion, have been used to study the primary action of kinetin. Gross chemical analysis showed that ribonucleic acid increased within 24 hours in response to kinetin application. 8-Azaguanine inhibited both kinetin-induced expansion and RNA synthesis; 5-fluorodeoxyuridine inhibited only the RNA synthesis.Cotyledons produced nitrate reductase activity in response to 20 mm nitrate only in the presence of either light or kinetin and especially in the presence of both. Abscisic acid and inhibitors of RNA and protein synthesis depressed this response. Inhibitors affecting chloroplast development and function did not reduce the response in the presence of light and kinetin.In vitro incorporation of 14C-L-leucine and '4C-L-phenylalanine into protein by various recombinations of microsomal and 160,000g supernatant fractions varied according to the pretreatment which the cotyledons had received before the preparation of the fractions. Stimulatory effects were mainly associated with the microsomal fractions.The formation of leucine-, valine-, and tyrosine-tRNA complexes by high speed supernatant fractions from differently pretreated cotyledons was also compared. The sharp stimulation of the process by adding tRNA was found to be independent of the kind of preincubation that the cotyledons used for the tRNA extraction had received. radioactivity from benzyladenine, applied to a tissue, could be recovered from its RNA mostly in the tRNA fraction. Also, some of the radioactivity of the acid hydrolysate of this fraction traveled on the chromatogram as benzyladenine. However, the crucial evidence that applied cytokinins in a responsive tissue do, in fact, promptly correct some specific tRNA deficiency, i.e., that of serine or tyrosine, is still lacking.Our data, relevant to the tRNA hypothesis, are presented in the later section of "Results" reporting the outcome of recombinations of parts of the protein-synthesizing machinery from control and kinetin-treated cotyledons. They are difficult to reconcile with the tRNA hypothesis, at least in its most naive form. Whatever the primary action of kinetin, the evidence presented suggests that in cotyledons, as a consequence of that action, a less specific activation of nucleic acid synthesis occurs. MATERIALS AND METHODSPreparation of Cotyledons. The cotyledons of fenugreek (Trigonella foenum graecum L.) can be separated from the embryonic axis by a cut through the dry seed, as the space between these parts is indicated by a groove in the seed exterior. Further manipulations-sterilization and washing of cut seeds, their transfer onto wet filter paper in Petri dishes, removal of seed coats 20 hr later, weighing and layering of cotyledons-were done in green safelight. Usually cotyledons were arranged in a 7-cm Petri dish containing one filter paper disc to which was added 3 ml of test solution containing 1 mg each of mycostat...

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Section: C-phenylalaninementioning

confidence: 99%

Action of Kinetin on Cotyledons of Fenugreek

Rijven

Parkash

1971

Plant Physiol.

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“…It has been established over the last 10 years that methylation of polymerase II genes, preferably in the promotor region, leads to their shut off from transcription (for reviews see [1,2]). Conversely, polymerase I genes are not affected by methylation as has been shown by injection of methylated and unmethylated rRNA genes into Xenopus oocytes [3].…”

Section: Introductionmentioning

confidence: 99%

DNA methylation inhibits transcription by RNA polymerase III of a tRNA gene, but not of a 5S rRNA gene

et al. 1990

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Methylation of cytosine in the DNA inhibits the transcription by RNA polymerase II in higher eukaryotes, but has no infhtence on RNA polymerase I transcription. The effect on RNA polymerase III was unknown, so far. Two polymerase III genes: a type 1 5s rRNA gene and a type 2 tRNA gene were methylated in vitro with a purified eukaryotic DNA methyltransferase (EC2.1.1.37) and their transcription was analyzed in Xenopus oocytes. The 5s rRNA gene, an oocyte 5s rRNA gene from X. luevis which is subject to developmental inactivation, was not alfected by methylation. Conversely, transcription of the tRNA gene was 8m inhibited by methylation with the eukaryotic methyltransferase. H/au1 and HpaII methylation left its transcription unaffected.

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“…Brown and Sasaki (5) found that total protein increases during induction of cold hardiness in mimosa epicotyl and hypocotyl tissues, while no observable quantitative changes occur in total tRNA and rRNA in either tissue. Thus, modification of isoaccepting tRNAs such as glycyl-tRNAs in soybean could regulate protein synthesis even if RNA content of the tissue remains relatively constant (23). Since plant response to freezing stress involves formation of new proteins which affect membrane permeability to water and solutes (11), soybean response to chilling stress also may involve a similar mechanism (27).…”

Section: Resultsmentioning

confidence: 99%

Isoaccepting Transfer Ribonucleic Acids during Chilling Stress in Soybean Seedling Hypocotyls

Yang¹,

Brown²

1974

Plant Physiol.

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Total aminoacylation of glycine and leucine transfer RNAs was compared between chilled and nonchilled hypocotyls of 7-day-old soybean seedlings. Total charging was greater for both specific transfer RNAs from nonchilled sources. Isoaccepting transfer RNA species for glycine and leucine were fractionated using reverse phase column chromatography. Leucyltransfer RNAs were fractionated into six distinct fractions with relatively small shifts appearing in specific fractions between chilled and nonchilied sources. Glycyl-transfer RNAs were fractionated into two distinct fractions with major shifts appearing for both fractions between chilled and nonchilled sources.It is known that RNA and protein metabolism relate closely to chilling injury and frost resistance of plants (13). Dure (8) suggests that translational control of protein synthesis is functional in higher plant development, while Anderson and Gilbert have shown tRNAs to be involved in translational control of hemoglobin synthesis (3). Further, quantitative and qualitative changes in isoaccepting tRNAs of plants have been related to changes in physiological state (2, 26) and environmental factors (6). The purpose of this investigation was to determine if aminoacylation of isoaccepting tRNAs is related to chilling stress in soybean seedlings. MATERIALS AND METHODSSoybean Tissue. Soybean (Glycine max L.) seeds were germinated and grown in vermiculite at 28 C with a day length of 15 hr and a light intensity of 800 ft-c. After 6 days, treated seedlings were placed at 5 C for 1 day while control seedlings were maintained at 28 C. Hypocotyls of nonchilled and chilled seedlings were excised for tRNA preparation.Other groups of soybean seeds were germinated and grown in the dark at 28 C. After 5 days, hypocotyls were excised for aminoacyl-tRNA synthetase preparation. Five-day-old etiolated hypocotyls were found to yield greater aminoacyl-tRNA synthetase activity than 7-day-old green hypocotyls. bean hypocotyl tRNA sources to eliminate enzyme activity as a variable during chilling.Transfer RNA Preparation. Transfer RNAs were isolated and purified from chilled and nonchilled soybean hypocotyls by a modification of the method of Vanderhoef et al. (24).Hypocotyl tissues were homogenized in a Waring Blendor in 0.1 M sodium acetate buffer, pH 4.5, 50 mm NaCl, 20 mM MgCI2, 10 mg/ml of bentonite, and 0.3% SDS' (w/v). After homogenates were filtered through double-layered cheesecloth, filtrates were centrifuged for 15 min at 30,000g. An equal volume of water-saturated phenol was added to supernatant solutions. After samples were stirred for 1 hr at 4 C and centrifuged for 15 min at 30,000g, aqueous layers were removed and volumes were determined. RNA was precipitated from aqueous solutions by addition of 2.5 volumes of 95% ethanol at -20 C. Precipitates were centrifuged at 30,000g for 15 min and resuspended in 50 ml of buffer A: 20 mm sodium acetate buffer, pH 4.5, 50 mm NaCl, and 10 mi MgCI2. Following centrifugation of resultant solutions for 5 min at 10,000g, su...

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Transfer RNA and Cell Differentiation

Cited by 137 publications

References 133 publications

Action of Kinetin on Cotyledons of Fenugreek

Action of Kinetin on Cotyledons of Fenugreek

DNA methylation inhibits transcription by RNA polymerase III of a tRNA gene, but not of a 5S rRNA gene

Isoaccepting Transfer Ribonucleic Acids during Chilling Stress in Soybean Seedling Hypocotyls

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