Article

Changes in the Pattern of Protein Synthesis Induced by 3-Indolylacetic Acid

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Abstract

Experiments have been performed to investigate whether indoleacetic acid changes the balance between the rates of synthesis of different kinds of proteins. Sub-apical sections of etiolated peas were incubated with (14)C- or (3)H-labeled amino acid, and combined to give dual-labeled tissue. Cell fractions were prepared by differential centrifugation, and the dual-labeled protein of each fraction analyzed by gel-filtration. When 2 x 10(-5)m indoleacetic acid was included with (14)C-labeled amino acid, but not with the (3)H-labeled amino acid, pronounced changes occurred in the pattern of incorporation of the (14)C label into protein. These changes were greatest in the proteins of the particulate fraction which included nuclear material. Although the pattern of incorporation of lysine was shown to be different from that of leucine, the changes induced by indoleacetic acid were quantitatively similar whichever amino acid was used as a precursor. Dual-labeled protein was further fractionated using column chromatography on DEAE-cellulose. The results suggested that the effect of indoleacetic acid may not be completely general, and that the pattern of synthesis of many proteins may be unaltered by indoleacetic acid. When tissue was preincubated with 10 mug/ml actinomycin D for 30 minutes, incorporation of amino acid into protein was reduced but not abolished. Actinomycin D did, however, prevent the changes in the pattern of protein synthesis which were induced by indoleacetic acid.

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... A technique of double labelling similar to that described by Patterson & Trewavas (1967) was the dark is compared with the ratio of incorporation by discs in the light and dark. In Fig. 4 the results of four such dual-labelling experiments are shown. ...
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The influence of indoleacetic acid, 0.03% CO(2), and malate on protein metabolism of etiolated Avena sativa coleoptile sections has been investigated. All three were found to elevate both the rate of incorporation of labeled leucine into protein, and the level of soluble protein. The combination of indoleacetic acid and CO(2) stimulated these values in an additive or weakly synergistic manner, in contrast to the nonadditive influence of malate and CO(2). Evidence is presented that cyclo-heximide inhibited the stimulation of protein synthesis by CO(2), and that indoleacetic acid increased the incorporation of (14)C-bicarbonate into protein. These data are discussed in the context of CO(2)-stimulated growth of etiolated tissue, and proposals that CO(2)-stimulated growth involves dark CO(2) fixation.
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1After some false starts in which inactive plant substances were isolated, the isolation and identification of auxin as the growth substance at the meristems and of ethylene as the ripening agent in climacteric fruits represented outstanding achievements.2In early work, the non-localized origin of auxin at the meristem and its possible transport for coleoptile development were obscured by the superimposition on the results of physiological experiments of the idea of a close parallelism between the plant-growth substances and mammalian hormones. At that time, an absence of chemical instrumentation, suitable for measurement of the tissue levels, compounded the difficulty in interpreting available physiological evidence.3Member(s) of each of the five groups of naturally occurring plant-growth substances, namely the auxins, cytokinins, gibberellins, ethylene and the growth inhibitors, including abscisic acid, are biologically active at a concentration of 10 μm or less, however, and in this respect they would appear to qualify as candidate phytohormones.4The sensitivity of plant cells to phytohormones contributes to plant growth and development, and both the variations in sensitivity, for example, of wheat coleoptiles towards growth and the growth of the coleoptiles per se give parallel unimodal relationships with regard to time; the curve representing sensitivity precedes that for growth. A new graphical analysis implies that the growth sensitivity and growth rate functions are mutually interdependent.5The assumption is made in point 4 that growth substance complexes with receptor protein in growth-sensitive cells, and the concept of receptors would provide explanation for the obvious amplification of effects induced by growth substances.6Numerous biological situations occur in which the presence of significant amounts of plant hormone controls growth and development. In gravitropism and phototropism, tropistic curvature depends on the difference in physiological concentration of auxin on the two sides of the organ concerned. In infected tobacco plants, the cytokinin to auxin ratios for the tumours determine the kind of development (tumours and shoots, tumours only or tumours plus roots), which takes place.7Auxin-binding protein has been identified immunologically, and isolated. Work with hormone receptors for gibberellin does not afford unequivocal evidence for more than one primary site of action. Hitherto, no specific receptor protein is known for cytokinins.8Clear evidence derives, both from structure–activity relationships and from unimodal concentration–response curves, for receptor specificity to auxin action. There is also evidence for a structure–activity relationship in respect of the cytokinin series of compounds.9From the evidence (points 1–8), there emerges a picture of hormone-induced growth and development of plant cells, which have been made sensitive to hormone through the presence of specific receptor proteins.10That plant growth and developmental processes involve changes in gene expression would seem to follow from the totipotent nature of meristematic cells, which are capable of specialization in response to phytohormones.11Auxin regulates de novo synthesis of mRNAs encoding polypeptides essential to the auxin-induced early process of cell elongation. In fact, auxin regulates the concentrations of several authenticated mRNAs and proteins, for example, in elongating soyabean hypocotyl sections.12Furthermore, two cDNA clones, termed pJCW1 and pJCW2 have been isolated with the properties expected of mRNAs involved in the rate-limiting stage of cell elongation. The evidence suggests that the change in relative abundance of the JCW1 and JCW2 RNAs is an obligatory auxin-dependent response. Hence, the action of cytokinin in auxin-induced cell elongation would seem to be concerned with the inhibition of rate-limiting proteins, and in fact cytokinin inhibits protein synthesis in excised soyabean hypocotyl.13Biosystemic experiments on some rapid effects of synthetic auxin growth regulators on mRNA levels in vitro show that there is only partial similarity between those found in pea and soyabean spp. (Leguminosae).14Two identified sequences, namely TGATAAAAG and GGCAGCATGCA, of two auxin-regulated soyabean genes afford a means for determining whether the auxin-regulation of expression of these genes involves trans-acting regulatory factors.15The obligatory auxin-induced responses with regard to cell elongation and growth (q.v.) would seem to precede the somewhat mechanical growth properties by which auxin receptive cells secrete H+ and lower the pH to yield increased cell-wall plasticity.16In vertically oriented soyabean seedlings, auxin-regulated RNAs are distributed symmetrically in the elongating region of the hypocotyl, whereas in horizontally oriented seedlings the distribution becomes asymmetrical within a few minutes of horizontal gravitational stimulation. The dynamic expression of auxin-regulated genes is related to the morphogenetic response, initiated by re-distribution of endogenous auxin (point 6).17In the germination of seeds, the mobilization of food reserves requires hydrolytic enzymes and, in barley grains, gibberellic acid induces de novo biosynthesis of α-amylase and protease. The genetic implications are discussed, and the requirement of dicotyledonous and gymnospermous seeds for the presence of gibberellins is explored.18In ripening climacteric fruits, ethylene-induced change(s) in gene expression cause de novo biosynthesis of polygalacturonase, which degrades the cell-wall pectin fraction.19Accordingly, incontestible evidence has been mustered for the proposition that hormone-regulated plant growth and development involves hormone-regulated gene expression.20As well as the phytohormones, certain environmental factors, such as white light and stress (including anaerobiosis, chilling, heat shock, heavy metal exposure, u.v. light and wounding) have the capacity to regulate gene expression in plants at important stages in growth and development. Discussion at the genetic level focuses on changes produced by:21The synthesis of phytohormones is significant. For example, as u.v. light-induced regulation of genes produces enzymes for auxin synthesis, it may be responsible in seeds for the endospermal generation of auxins, concerned with the epicotyl/hypocotyl growth in the seedlings.22Hormones and certain environemental factors (q.v.) initiate some of the numerous stages in plant growth and development, but the regulatory factors are obscure in some other biological situations, such as:23Utilization of an appropriately re-constituted plant DNA polymerase i in vitro system might enable the type and frequency of misincorporation, produced by plant-growth factors, to be studied. Base-pair substitution changes were produced in strains of crop plant, made resistant to a specific herbicide by genetic engineering (see Hathway, 1989). It is feasible that auxin may behave as a reagent in the chemical sense to effect intramolecular change(s) in some of the sequences concerned, leading to the frame-shift changes observed (see Ainley et al., 1988).
Chapter
Proteins are essential components of protoplasm, playing a key role in its structure and metabolism (enzymes). The increase in the amount of proteins is the basis of growth phenomena, and the differentiation of the living body is closely related to the differentiation of the protein composition of its cells, tissues and organs (Bonner, 1965). The control of the protein synthesis is therefore a key problem in the development of living beings. In plants, many factors, endogenous and exogenous, are known to be involved in this control. Hormones belong to the more important endogenous factors affecting protein metabolism, to the extent that mechanism of hormone action has been generally assumed to be connected mostly with the control of protein synthesis.
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Full-text available
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The naturally occurring auxin, indole‐3‐acetic acid, is thought to regulate normal growth and developmental processes in higher plants, including cell extension, cell division, and cell differentiation. Applied auxins, including synthetic and natural auxins, can dramatically alter normal growth and developmental patterns, and applied auxins have been shown to modify expression of genes transcribed by all three classes of nuclear RNA polymerase (i.e., RNA polymerase I, II, and III). The regulation of specific genes by auxin may occur over long (e.g., several hours to days) or short (e.g., minutes) time spans after hormone application. The more interesting responses to applied auxins are the short‐term responses since these are more likely primary responses to the hormone. Several experimental approaches have been used to demonstrate that applied auxins rapidly alter gene expression, and these include in vivo labeling of polypeptides, in vitro translation of mRNAs, and cDNA cloning of auxin‐regulated mRNAs and analysis by RNA hybridization. At least in some cases, auxin‐regulated gene expression has been shown to be controlled at the level of transcription. Several auxin‐regulated genes have been or are being sequenced, and the portions of these genes that are required for auxin regulation are under investigation.
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Synthesis of growth-limiting proteins (GLP) is required for continued auxin-induced elongation of oat (Avena sativa L.) coleoptiles. In order to determine whether GLP synthesis is dependent or independent of auxin, a double-labeling ratio technique, coupled with disc-gel electrophoresis, has been used to assess the effect of auxin on the pattern of protein synthesis. Sections were peeled to enhance amino-acid uptake; proteins were labeled with [(14)C]- or [(3)H] leucine in the presence or absence of indole-3-acetic acid for 40 min to 6 h, and were separated into soluble, membrane-associated, and wall-associated fractions. Regardless of the conditions used, or the protein fraction examined, no changes in response to auxin were detected in the pattern of protein synthesis. In order to escape detection by this technique an auxin-induced protein would have to comprise less than 0.75% of the total newly synthesized protein. Thus the synthesis of GLP appears to be independent of auxin. The same technique has been used to follow protein turnover. During the chase, proteins are initially degraded at an average rate of 8% h(-1), and some protein bands showed as much as 14% h(-1) degradation. No protein was detected which had a turnover rate as rapid as the GLP.
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Using a dual radioactive labelling technique, the large 2,4-D induced increase in invertase activity in root tissue of chicory (Cichorium intybus) could not be attributed to de novo protein synthesis. The highly active enzyme could have arisen by modification of an inactive enzyme precursor.
Chapter
This chapter provides an overview of plant cell-walls. The cell wall is an envelope that encases the plant cell. The wall must be rigid enough to give the plant strength and form, and yet, if necessary, it must yield freely to facilitate growth. The network of cell walls, where adjoining cells have a wall in common, provides in a plant the structural framework analogous to both the skin and the bones of an animal. In some plants, especially those having woody tissues, the strength of this cell-wall network is prodigious. However, despite their apparently tough sheathing, the cells of the growing regions of a plant are able to extend to many times their initial length. The cell wall lies outside the plasma membrane, which defines the boundaries of the cell itself. The wall is freely permeable to most molecules, but the membrane exhibits selective permeability tending to concentrate certain dissolved molecules and ions inside the cell. The presence of such charged components as acidic polysaccharides within the wall imparts ion-exchange properties to the wall. The chapter discusses the concepts related to the types of cell-wall polysaccharides and elaborates the methods used in the elucidation of primary-wall structure. It also presents an overview of cell-wall glycoproteins.
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Exogenous application of hormones is one of the most common methods in research into the mode of action of such substances. The rationale behind such approaches is based mainly on the idea of replacement of the endogenous, naturally occurring hormone by an exogenous hormone, the level of which may be controlled and its effect monitored. This is fairly easily accomplished in animal systems, where the gland synthesizing a particular hormone can be dissected out and the target tissue monitored after application of the exogenous hormone via the blood stream. This is rarely easy and often impossible to achieve with plant material because in most instances any given hormone may be produced in more than one location within the plant. Furthermore, the same organ or cell which produces the hormone may also be the target.
Chapter
Nachdem immunologische Methoden mit Erfolg zur quantitativen Bestimmung tierischer Hormone herangezogen worden sind, ist es nicht überraschend, daß nunmehr auch erste Daten zu immunologischen Bestimmungen von Phyto-hormonen vorgelegt wurden (FUCHS u. FUCHS. FUCHS et al.). Tatsächlich werden spezifische Antikörper gegen IES und Gibberellin in Ratten gebildet, die zuvor mit Hämocyaninconjugaten dieser Hormone immunisiert worden waren. Durch Ausarbeitung spezifischer Immunreaktionen, speziell einer Hemmung der Inaktivierung modifizierter T4-Bacteriophagen, gelingt eine Bestimmung beider Hormone. Während die Reaktion auf Gibberelline weitgehend spezifisch ist (S. 130) reagieren im Kreuztest die IES-Sera auch mit Indolacetyl-ε-aminocaprylsäure, Tryptamin und Tryptophan. Eine Vorreinigung IES-haltiger Extrakte ist daher auch für die immunbiologische Bestimmung der Indolauxine notwendig. Die arbeitsintensive Methodik gleicht einstweilen den Vorteil aus, den die immunologische Bestimmung dadurch bietet, daß Wechselwirkungen mit wachsturnsaktiven Verbindungen anderer chemischer Struktur ausgeschlossen sind.
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Applications of auxin to the tips of intact aged pea Pisum sativum L. var Alaska epicotyls resulted in an increase in the content of polyribosomes and poly(A) and in the capacity of isolated polysomes to support protein synthesis in vitro. Few changes were seen in the two-dimensional gel patterns of silver-stained proteins accumulated (or degraded) in vivo even after 15 hours of auxin treatment. In contrast, substantial changes were evident in the two-dimensional gel fluorographs of polypeptides generated in vitro by total RNA and by polysomal RNA from tissue treated with auxin for only 6 hours. Of the 200 spots resolved by fluorography, total RNA from auxin-treated tissue generated 33 spots with increased intensity and 10 with decreased intensity; polysomal RNA yielded 33 spots which increased and only three that decreased. In general, the polypeptides that increased in intensity were higher molecular weight and those that decreased were lower molecular weight. These changes occurred prior to growth and might be prerequisite for the auxin-induced slow growth response seen in this aged tissue.Comparisons were made between the changes in RNA and protein metabolism occuring during aging and after wounding and auxin treatment of aged tissue. Aging causes a decline in poly(A), polysomes, and protein synthesizing capacity, whereas wounding and auxin treatment cause increases. Wounding appears to act primarily at the level of translation, whereas auxin has a greater effect on transcription. It is argued that the use of excised tissue to study auxin effects on RNA and protein metabolism should be avoided.
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Further studies with inhibitors of protein synthesis are presented to support the conclusion, drawn from work with chloramphenicol, that protein synthesis is a critical limiting factor in auxin-induced cell expansion. The indoleacetic acid-induced elongation of oat coleoptile sections was strongly inhibited by dl-p-fluorophenylalanine, and the inhibition is antagonized by phenylalanine. Puromycin at 10(-4)m very strongly inhibited the indoleacetic acid-induced growth of oat coleoptile and artichoke tuber sections and exerted a less powerful effect on pea stem sections. As found earlier with chloramphenicol, concentrations of puromycin effective in inhibiting the growth of coleoptile sections had quantitatively similar effects on protein synthesis, as measured by the incorporation of C(14)-leucine into protein of the coleoptile tissue. Several analogues of RNA bases were also tested, but while 8-azaguanine very strongly inhibited growth of artichoke tuber disks, 6-azauracil was the only one of this group clearly inhibitory to growth in coleoptile or pea stem sections. Actinomycin D actively inhibited both elongation and the incorporation of C(14)-leucine into protein in oat coleoptile sections. Inhibition of the 2 processes went closely parallel. Actinomycin D also powerfully inhibited growth of artichoke tuber disks. All the compounds effective in inhibiting growth generally inhibited the uptake of leucine as well. The possibility that auxin causes cell enlargement in plants by inducing the synthesis of a messenger RNA and of one or more new but unstable enzymes, is discussed. Possible but less favored alternative explanations are: A) that auxin induces synthesis of a wall protein, or B) that the continued synthesis of some other unstable protein (by a process independent of auxin) may be a prerequisite for cell enlargement.
Article
Apices of etiolated decapitated Alaska pea seedlings were painted with aqueous lanolin + IAA ± various inhibitors of RNA or protein synthesis. A subapical segment from the epicotyl was removed for measurements of growth and the soluble protein content and cellulase activity of enzyme extracts.During the first 18 hours, the main growth response to IAA was an increase in segment diameter; elongation was inhibited. The amount of extractable cellulase activity per segment and the diameter increased at exactly the same rates relative to controls. In the next 2 days IAA induced rapid cell division and the formation of root primordia. Cellulase activity per segment, per unit fresh weight, and per unit soluble protein all increased markedly to levels many times higher than in controls. Chloramphenicol, azaguanine, puromycin, and actinomycin D all interfered with protein synthesis, the growth responses, and the development of cellulase activity. In the absence of IAA, cellulase activity decreased.It is concluded that cellulase is subject to turnover in this tissue and that the rate of its synthesis is controlled by auxin concentration. It is proposed that cellulase action on microfibrils in vivo plays an essential role in a variety of growth processes, particularly lateral cell expansion.
Article
An approach to the study of the effects of auxins on plant tissue during auxin-induced cell elongation has been made by following the incorporation, from various suitably labeled metabolites, of isotopic carbon into the varied cellular components.Indoleacetic acid (IAA) was found to have little or no effect on the rate of incorporation of the C14 of carboxyl-labeled amino acids (glycine and leucine) into the proteins of corn and Avena coleoptiles. Protein level remains constant in excised sections of these organs over periods of 6 hr. and longer, and is independent of the presence or absence of added growth substance. IAA was found to have a promotive effect on the rate of incorporation of the carbon of carboxyl-labeled acetate into the lipides of the Avena coleoptile although this effect is small compared to the effect of IAA on growth.Chromatography and radioautography of the soluble constituents of Avena coleoptile sections which had been previously supplied with either carboxyl-labeled acetate or uniformly labeled sucrose failed to reveal any major effect of IAA although the carbon of both substrates is rapidly converted to a variety of compounds in the plant.Indoleacetic acid slightly depresses the over-all rate of incorporation of the carbon of labeled acetate or sucrose into the components of the cell wall of the Avena coleoptile. This over-all depressant effect is compounded of a considerable increase in the rate with which the noncellulosic polysaccharides become labeled and lesser effects, generally inhibitory, on other components.
Article
A method was devised for following the growth rate of oat coleoptile cylinders with sufficient precision to measure the growth that occurred in 1 minute; the solution treating the section could be completely replaced with a different solution within 15 seconds. It was found that response of the elongation rate to changes in temperature was complete within 20 seconds, with a Q10 of about 3.5 in the temperature range 2–23°C, and that response to treatment with cyanide, or to treatment with oxygen when the tissue had been deprived of it, was completed in a few minutes. The results are interpreted as indicating that the rate of elongation is controlled directly by the rate of a metabolic reaction or reactions rather than by a physical property like steady-flow viscosity, and hence that the growth mechanism has the character of a chemorheological process as opposed to a plastic flow.The growth rate of oat coleoptile cylinders becomes promoted, after auxin is added, only after a lag of about 10–15 minutes at 23°C. This lag is not determined primarily by the rate of penetration of auxin into the tissue; it is approximately twice as long at 13°C. This is considered to indicate that the action of auxin is not directly upon the growth-controlling reaction, but affects the latter indirectly via temperature-sensitive metabolic pathways.
Article
As part of a study of protein and peptide metabolism lysine was synthesized with C14 in the ε position and resolved into the L and D isomers. 10 mg. of labeled lysine dihydrochloride (either L- or D-) and 0.66 gm. (wet weight) of guinea pig liver homogenate were added to a reaction mixture containing 1.3 per cent of an amino acid mixture corresponding to the composition of casein except for lysine and 0.01 M α-ketoglutarate, all in a final volume of 4 ml. of isotonic saline solution.(1) The reaction was carried out under oxygen for 6 hours at 38°.
Article
The hypothesis that nascent R-RNA associated with neosomes forms the unit responsible for the synthesis of ribosomal protein leads to a number of self-consistent relationships. The RNA of a 70 s ribosome is long enough to act as template for six molecules of ribosomal protein. As the complete 70 s ribosome contains 36 of these units the template must operate six times, i.e. it should pass over six points of synthesis. The cell's content of neosomes is just sufficient to provide six per template. The rate of amino acid incorporation per site in such a complex is roughly the same as the rate calculated for non-ribosomal proteins. The hypothesis is subject to test by observing the incorporation of tracer-labeled bases and amino acids.
Article
Young stem sections of dwarf peas (Progress No. 9) grown in light contain at least seven peroxidase isozymes separable by electrophoresis on starch gel. An eighth isozyme appears as the tissue elongates and ages, on or off the plant. The appearance of this isozyme in excised sections is repressed by application of the plant growth hormone, indole-3-acetic acid.
Article
1. The effect on RNA synthesis in rat liver of thyroidectomy and the administration of thyroid hormone, especially during its physiological latent period, was studied by determining: (a) the activity of DNA-dependent RNA polymerase in isolated nuclei; (b) the rate of synthesis of nuclear and cytoplasmic RNA in vivo; (c) polyribosomal sedimentation profiles; (d) the response of microsomes and ribonucleoprotein particles to polyuridylic acid; (e) the effect of inhibitors of RNA and protein synthesis on the biological activity of hormones. 2. The DNA-dependent RNA-polymerase activity of isolated rat-liver nuclei was lowered by thyroidectomy and stimulated by the administration of tri-iodo-l-thyronine or l-thyroxine (2-25mug./100g. body wt.) to both normal and thyroidectomized rats. In thyroidectomized rats, the activity of the Mg(2+)-activated RNA-polymerase reaction (for which the product is mainly ribosomal type of RNA) was stimulated at 10-12hr. after a single injection of tri-iodothyronine, reaching a peak value of 60-90% stimulation at 45hr. after hormone administration. The Mn(2+)/ammonium sulphate-activated RNA-polymerase reaction (for which the RNA product is more DNA-like) was not affected for 24hr. after hormone administration but stimulated by 30-40% at 45hr. The response of both RNA-polymerase reactions to the hormone in vivo paralleled the physiological response but the enzyme was not stimulated by the addition in vitro of the hormone to isolated nuclei. 3. Within 3-4hr. after tri-iodothyronine administration to thyroidectomized rats, the specific activity of rapidly labelled nuclear RNA, after a 10min. pulse of [6-(14)C]orotic acid, was 30-40% greater than the control values, the stimulation reaching 100 and 200% at 11 and 16hr. respectively after hormone administration. Longer exposures to [6-(14)C]orotic acid and [(32)P]phosphate showed that the hormone accelerated the synthesis of mitochondrial, microsomal (or ribosomal) and soluble RNA. The greater part of the labelled nuclear RNA was of the ribosomal type. The hormone-induced increases in the incorporation of radioactive precursors into RNA were not preceded, but followed, by enhanced uptake of the precursor. There was no change, per g. of liver, of DNA, nuclear RNA or soluble RNA, but there was a 40-60% increase in the amount of ribosomal RNA between 35 and 45hr. after a single injection of tri-iodothyronine to thyroidectomized rats. 4. Coinciding with the increase in ribosomal RNA after hormone administration was an increase in the average size and amount of polyribosomes. The newly formed ribonucleoprotein particles, or messenger RNA attached to them, or both, were more firmly bound to microsomal membranes after hormone treatment. 5. Polyuridylic acid caused a bigger stimulation of incorporation of [(14)C]phenyl-alanine by ribonucleoprotein particles, but not by microsomes, from thyroidectomized rats as compared with preparations from normal animals. The response of ribonucleoprotein particles to polyuridylic acid was lowered after tri-iodothyronine treatment of thyroidectomized rats. 6. Actinomycin D, 5-fluorouracil, puromycin and cycloheximide caused a 70-100% inhibition of the stimulatory effect of l-thyroxine and tri-iodo-l-thyronine on basal metabolic rate and growth rate in both normal and thyroidectomized animals. Administration of actinomycin D also abolished the stimulation of RNA polymerase by tri-iodothyronine. 7. It is concluded that regulation of nuclear and ribosomal RNA synthesis is an essential step leading to the biological action of thyroid hormones and that the formation of new ribosomes is an important aspect of the control of cytoplasmic protein synthesis by these hormones.
Article
A fractionation procedure is proposed for the subcellular components of the apical portion of the pea seedlings. This procedure emphasizes isolation of microsomal particles and separation of nuclei from cytoplasmic components.Amount and distribution of DNA, RNA, protein and phosphorus of phosphoprotein of these components from the homogenates of the apical portion of pea seedlings are reported. 50–60 per cent of the cellular RNA is found to be located in the microsomal fraction. This apical portion is further divided into the tip section and the stem section. Analyses of RNA, and protein of all the subcellular components from these two sections show that the components from the tip section are two times more enriched in RNA.
Article
The nitrogen metabolism of isolated pea stem sections as affected by arsenite, fluoride, and iodoacetate growth inhibitors in auxin solutions was studied. The changes in growth and metabolism caused by these inhibitors are discussed.
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Action of inhibitors of RNA and protein synthesis on cell enlargemenit Hormone-induced repression of a peroxidase isozymne in plant tissue
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The effects of 3-indolyl- acetic acid on the metabolism of RNA and protein in etiolated sub-apical sections of Pisuin sativumn
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Graphic determiinlation of isotope activity ratios in simul-tanleous assay of tritium anid carhon-14
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Effects of IAA onl metabolic pathways
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Synthesis of ribonucleic acid in plants
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