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PubMed1980

Peroxide Levels and the Activities of Catalase, Peroxidase, and Indoleacetic Acid Oxidase during and after Chilling Cucumber Seedlings.

The activities of catalase, peroxidase, indoleacetic acid (IAA) oxidase and peroxide levels in cucumber plants during and after chilling were determined. During 96 hours at 5 C and 85% relative humidity, catalase activity declined, IAA oxidase activity increased, and peroxide concentrations increased. Peroxidase activity was not affected by chilling. When chilled plants were returned to 25 C to recover, enzyme activities and peroxide concentration were restored to their prechilling levels. The increase in peroxide and IAA oxidase activity may inactivate or destroy IAA and thus retard growth.

Journal Article↗
PubMed1990

Transport of indoleacetic Acid in intact corn coleoptiles.

We have characterized the transport of [(3)H]indoleacetic acid (IAA) in intact corn (Zea mays L.) coleoptiles. We have used a wide range of concentrations of added IAA (28 femtomoles to 100 picomoles taken up over 60 minutes). The shape of the transport curve varies with the concentration of added IAA, although the rate of movement of the observed front of tracer is invariant with concentration. At the lowest concentration of tracer used, the labeled IAA in the transport stream is not detectably metabolized or immobilized, curvature does not develop as a result of tracer application, and normal phototropic and gravitropic responsiveness are not affected. Therefore we believe we are observing the transport of true tracer quantities of labeled auxin at this lowest concentration.

Journal Article↗
PubMed1995

Transcriptional regulation of PS-IAA4/5 and PS-IAA6 early gene expression by indoleacetic acid and protein synthesis inhibitors in pea (Pisum sativum).

The transcription of two genes, PS-IAA4/5 and PS-IAA6, in pea is induced by indoleacetic acid (IAA) and protein synthesis inhibitors such as cycloheximide (CHX) and anisomycin (ANI). Induction by IAA is rapid, taking 5 and 7.5 minutes for PS-IAA4/5 and PS-IAA6, respectively, and is independent of IAA concentration and whether IAA has a free or esterified carboxyl group (ethyl-IAA). The rate of mRNA accumulation, however, is dependent on hormone concentration, and is greater with IAA than with ethyl-IAA. The turnover rates (t1/2) of the PS-IAA4/5 and PS-IAA6 mRNAs are 60 and 75 minutes, respectively, and are not affected by IAA. CHX or ANI induce the transcription of PS-IAA4/5 and PS-IAA6 more slowly than IAA (5 to 10 minutes for PS-IAA4/5 and 20 minutes for PS-IAA6). While protein synthesis inhibitors stabilize both mRNAs, the rapidity of induction by CHX and ANI cannot be accounted for solely by mRNA stabilization. The relationship between mRNA induction and protein synthesis inhibition does not obey Michaelis-Menten kinetics, but rather is best described by a hyperbolic curve, suggesting the release of transcriptional repression by the inhibition of protein synthesis. RNA expression experiments with transgenic tobacco seedlings or with transfected pea protoplasts using PS-IAA4/5 promoter GUS or CAT fusions reveal that CHX transcriptionally activates PS-IAA4/5 gene expression. Thus, protein synthesis inhibitors have a dual effect on PS-IAA4/5 and PS-IAA6. (1) They stabilize both mRNAs (possibly by a translational arrest-linked process or by preventing the synthesis of a labile nuclease(s)). (2) They activate transcription (possibly by preventing the synthesis or function of a repressor).

Anisomycin↗
PubMed1976

Transport of 5-hydroxy-3-indoleacetic acid by spinal cord during subarachnoid perfusion.

The transport of [14C]5-hydroxy-3-indoleacetic acid (5-HIAA) by the spinal cord was investigated with spinal subarachnoid perfusions of 20 rhesus monkeys. For spinal white matter, [14C]5-HIAA was found to distribute in a tissue space of 50-55% and to exchange readily between tissue and blood across parenchymal capillaries. The data were analyzed with a model of the spinal cord as a cylinder and a mean capillary transfer half-time of 20 min determined. The spinal cord cleared [14C]5-HIAA from 19 mul/min of CSF. Administration of probenecid yielded a somewhat lower mean tracer clearance rate (14 mul/min) but did not alter the capillary exchange half-time or the distribution volume of [14C]5-HIAA in the spinal cord. The data suggest that capillaries within spinal white matter transport 5-HIAA by a mechanism which is insensitive to inhibition by probenecid and that lumbar CSF concentrations reflect only a small portion of total 5-HIAA production by the central nervous system.

Animals↗
PubMed1970

Effect of ethylene on the uptake, distribution, and metabolism of indoleacetic Acid-1-C and -2-C and naphthaleneacetic Acid-1-C.

The effect of ethylene on the uptake, distribution, and metabolism of indoleacetic acid (IAA)-1-(14)C, IAA-2-(14)C, and naphthaleneacetic acid (NAA)-1-(14)C in cotton stem sections (Gossypium hirsutum L., var. Stoneville 213) was studied. Stem sections excised from plants pretreated with ethylene for 15 hours transported significantly less (14)C-IAA and (14)C-NAA than control sections. Concomitant features of the reduction of (14)C-IAA transport were an increase in decarboxylation and a trend toward a reduction in total uptake. With (14)C-NAA, however, total uptake was significantly increased, and decarboxylation was unaffected.(14)C-IAA was rapidly converted to indoleacetylaspartic acid and many other metabolites in both control and ethylene-pretreated stem sections. Following transport, similar amounts of (14)C-IAA were recovered in the apical absorbing portion of the control and ethylene-pretreated sections. Significantly more (14)C-IAA metabolites, however, were recovered in this region of the ethylene-pretreated sections.Conversely, (14)C-NAA was metabolized more slowly than (14)C-IAA under identical experimental conditions, with the only major metabolite being naphthaleneacetylaspartic acid. Following transport the apical absorbing portion of ethylene-pretreated stem sections contained significantly more (14)C-NAA than the controls. These results suggested that the disruption of auxin transport by ethylene cannot be explained in terms of a more rapid metabolism of auxin in the treated sections. The increased (14)C-IAA metabolites in the absorbing portion of ethylene-pretreated sections appear to be the result, rather than the cause, of the ethylene-mediated disruption of IAA transport.

Journal Article↗
PubMed1990

Comparison of the effect of indoleacetic Acid and fusicoccin on the breakdown of phosphatidylinositol in maize coleoptiles.

The effect of indoleacetic acid (IAA) and fusicoccin (FC) on the breakdown of phosphatidylinositol in maize (Zea mays L.) coleoptiles has been studied. Coleoptiles were able to incorporate [(3)H] myo-inositol into the phospholipid fraction almost linearly for 8 hours. Thin layer chromatography analysis of total phospholipids showed that [(3)H]myo-inositol was incorporated only into phosphatidylinositol. Prelabeled coleoptiles treated with IAA showed a loss of the radioactivity incorporated in the phospholipid fraction, whose level decreased by 34% after 1 hour. Treatment with FC, on the contrary, did not modify the content of labelled phosphatidylinositol with respect to the control. The different effects of IAA and FC and a possible mechanism of IAA action on growth are discussed.

Journal Article↗
PubMedDate not supplied

[Indoleacetic acid levels in the potato organs during various stages of ontogenesis and the role their dynamics in the tuber growth regulation].

During ontogenesis of the potato (Solanum tuberosum L.), the content of indoleacetic acid (IAA) in different organs was determined. The dynamics of IAA in the leaves corresponded to changes in photosynthetic activity. The treatment with IAA increased the intensity of photosynthesis. It was shown that the IAA content increased in the leaves and that IAA ascended to the stem basal part in the second half of vegetation. The accumulation of IAA in the stem basal part gave rise to a positive gradient of sugar in the stem, differentiation of stolons and transport of assimilate in the grown tubers. A correlation was found between the content of IAA in tubers and the rate of its growth.

Indoleacetic Acids↗
PubMed2004

The plant hormone indoleacetic acid induces invasive growth in Saccharomyces cerevisiae.

Fungi must recognize plant-specific signals to initiate subsequent morphogenetic events such as filamentation that lead to infection. Here we show that the plant hormone indoleacetic acid (IAA) induces adhesion and filamentation of Saccharomyces cerevisiae. Genome expression profiling of cells treated with IAA identified Yap1, a fungal specific transcription factor, as a key mediator of this response. Strains lacking YAP1 (yap1-1) are hypersensitive to growth on IAA because they accumulate more IAA than can wild type. Members of a family of transporters the amino acid/auxin:proton symport permeases with homology to AUX1, a putative IAA transporter from plants, are up-regulated in the yap1-1 mutant. Deletion of any one of these transporters makes yap1-1 mutants more resistant to IAA by decreasing its uptake. The permease mutants are defective in IAA perception and filamentation. The ability of a fungus to perceive a plant hormone that causes it to differentiate into an invasive form has important implications for plant-pathogen interactions.

Dose-Response Relationship, Drug↗
PubMed1982

Agrobacterium Ti plasmid indoleacetic acid gene is required for crown gall oncogenesis.

A gene (iaaP) necessary for virulence and indoleacetic acid (IAA) production has been located on a nopaline Ti plasmid of Agrobacterium tumefaciens C58. iaaP function was established by using transformation to insert nopaline or octopine Ti plasmids into an avirulent, Ti plasmid-free mutant 1D1293-3 that was defective in IAA synthesis (iaaC(-)). The resulting transformants produced increased levels of IAA and virulence was restored. When these transformants were cured of their Ti plasmid, virulence and high IAA production levels were concomitantly lost. A Tn5 mutagenized TiC58 plasmid, deficient in the ability to direct increased synthesis of IAA, was inserted by transformation into mutant 1D1293-3. The resulting transformants 1D1293-3 (TiC58::Tn5) remained avirulent and iaaP(-). Restriction analysis of the TiC58::Tn5 plasmid DNA identified the iaaP gene at 20.9 kilobases to the left of the T-DNA. A major aromatic-amino-acid aminotransferase is coded by the iaaC gene, but not by the iaaP gene. The possible reasons for the iaaP locus to be situated outside the T-DNA region are discussed.

Journal Article↗
PubMedDate not supplied

Occurrence of 5-hydroxy-3-indoleacetic acid in urine from several animal species.

1. The normal levels of 5-hydroxy-3-indoleacetic acid (5HIAA) were determined in the urine of four species of laboratory animals (dog, rabbit, rat and guinea-pig). 2. When 5HIAA excretion was calculated as mg/24 h, the output in the four species was in the order of rabbit greater than dog greater than guinea-pig greater than rat; but when it was calculated as mu/mg of creatinine, the order was guinea-pig greater than rabbit greater than rat greater than dog. 3. There were significant differences in the excretion of urinary 5HIAA between males and females within two species: rats and dogs.

Animals↗
PubMed1983

Determination of endogeneous indoleacetic acid and tryptophol in mouse brain by high performance liquid chromatography with fluorometric detection.

A simple and sensitive method using high performance liquid chromatography with fluorometric detection has been developed for the identification and quantitation of the endogeneous tryptamine metabolites, indoleacetic acid (IAA) and tryptophol (TOL) in the normal mouse brain. The limits of sensitivity are 5pg for both IAA and TOL. The extract procedure from the brain is only to deproteinize samples. The mean concentrations of IAA and TOL in the mouse brain are 8.99 +/- 0.31 ng/g and 3.56 +/- 0.21 ng/g respectively. The effects of pargyline and tryptamine on the levels of IAA and TOL were also studied.

Animals↗
PubMedDate not supplied

Hill-acitivity and P700 concentration of chloroplasts isolated from radish seedlings treated with-indoleacetic acid, kinetin of gibberellic acid.

The Hill-activity (reduction of DCPIP or methylviolgen) and the concentration of P700 were studied in chloroplasts isolated from cotyledons of radish seedlings (Raphanus sativus L. saxa Treib), which had been grown with the addition of beta-indoleacetic acid (IAA), kinetin, or gibberellic acid. 1) The photosynthetic activity of young chloroplasts from 3 day old Raphanus seedlings is very high (c. 180 micron mol O2/mol chlorophyll X h) and decreases continuously thereafter with increasing age. The steady state Hill-activity is reached after 8 to 10 days (values of 55 to 50 micron mol O2/mg chlorophyll X h). 2) Chloroplasts from plants treated with IAA or kinetin not only exhibit higher plastoquinone levels 1,2, but also a higher P700-content and a higher Hill-activity. The promotion effect is more pronounced with kinetin (+36 tb 40%) than with IAA (+12 to 17%). 3) Gibberellic acid has a different effect on composition and activity of chloroplasts. In younger seedlings the Hill-activity appears to be somewhat stimulated, without promotion effect on plastoquinone 2 or P700 concentration. After 10 days GA3-treated plants show signs of chlorosis combined with a strong decrease in photosynthetic activity. 4) The data clearly demonstrate that the composition and activity of the photosynthetic apparatus are under phytohormone control. IAA and even better kinetin promote the light induced formation of pigment systems and electrontransport chains. GA3 seems to block the rebuilding of the photosynthetic apparatus under steady state conditions.

2,6-Dichloroindophenol↗
PubMed1990

Anions activate the oxidation of indoleacetic Acid by peroxidases from tomato and other sources.

Anionic peroxidase from tomato (Lycopersicon esculentum) fruit oxidized indoleacetic acid (IAA) slowly in the presence of Mn(2+) and dichlorophenol in acetate buffers. The addition of certain anions to the reaction mixture increased the rate of oxidation. Phosphate was one of the effective anions and exerted maximal activation at 0.1 molar. The most effective activator of tomato peroxidase was nitrilotriacetate (NTA) at an optimum concentration of 60 micromolar. Only 0.17 nanomolar peroxidase was needed to oxidize 0.1 micromole IAA/5 minutes in the presence of NTA compared to 650 nanomolar peroxidase for the same rate in the absence of NTA. Other effective anions were oxalate, pyrophosphate, malate, and citrate. Each activator exhibited an optimum concentration and higher concentrations were inhibitory. Anionic peroxidase from horseradish was activated by the same anions. A cationic peroxidase from horseradish and lactoperoxidase oxidized IAA in acetate buffer although anions activated these enzymes severalfold. Microperoxidase and other hematoporphrins also catalyzed IAA oxidation in the presence of anions. It is proposed that IAA oxidation by peroxidase may be important when vacuolar contents mix with peroxidase as during plant injury.

Journal Article↗
PubMed1982

Liquid-chromatographic determination of urinary 5-hydroxy-3-indoleacetic acid, with fluorescence detection.

We describe and evaluate a procedure for measuring urinary 5-hydroxy-3-indoleacetic acid by "high-performance" liquid chromatography. After a simple organic extraction, the analyte and internal standard are chromatographed on a reversed-phase column and are detected by native fluorescence. The detection limit (3 ng per injection), between-day precision (CV 5.2%), absolute recovery (70%), analytical recovery (99%), and working linear range (up to 15 mg/L) have been determined. Compared with colorimetric results with nitrosonaphthol, values obtained with the chromatographic method are significantly lower. Reference values and clinical experience with the method are reported. The method is simple, free from interferences, and suitable for use in routine analysis in the clinical laboratory.

Adult↗
PubMed1989

Determination of urinary 5-hydroxy-3-indoleacetic acid by an automated HPLC method.

A HPLC method for the quantitative determination of 5-hydroxy-3-indoleacetic acid (5-HIAA) in urine is described. The method is based on ion-pair chromatography, reversed phase (RP) column material and specific fluorimetric detection at 300 nm and 355 nm. Sample preparation and gradient elution were avoided by using a column-switching technique. The sensitivity of the assay was excellent for clinical routine analysis, with a detection limit of 0.2 mg/L 5-HIAA. No endogenous or exogenous interference problems arose. Intra- and interassay precision was good, with observed coefficients of variation of 1.5 to 2.6% and 2.1%, respectively. Recoveries were 93 to 98%. The system described can be used for clinical diagnosis and therapy follow-up of carcinoid tumors. It has been running for over a year without disturbances and with a minimum of technical attendance.

Autoanalysis↗
PubMed1987

Interaction of indoleacetic Acid with its inositol and glucoside conjugates in Avena coleoptile curvature.

Avena coleoptile curvature is promoted by indoleacetic acid (IAA) IAA-glucoside, and IAA-inositol when these substances are applied in agar to the decapitated apical end of deseeded plantlets. Absorption of [(3)H]IAA-inositol over a wide range of concentrations during the 20 hour period of incubation is only 20 to 50% of the applied amount, compared with 85 to 92% of uptake of the applied [(3)H]IAA at equimolar concentrations. The absorption of IAA-glucoside could not be readily measured. The stimulation by both IAA-conjugates is very similar to that of free IAA at low concentrations (0.2 and 0.4 micromolar), but much less at higher concentrations. The interaction of free IAA with IAA-glucoside is additive or synergistic (depending on concentration). The interaction of free IAA with IAA-inositol is an inhibition (i.e. less than additive). The simultaneous application of equimolar concentrations of free IAA does not change the chromatographic pattern of the metabolic products of [(3)H] IAA-inositol. One of the more polar metabolites of [(3)H]IAA-inositol has chromatographic characteristics similar to the major polar metabolite of free [(3)H]IAA on an isocratically eluted reversed phase C(18) high performance liquid chromatography system that separates a number of IAA sugar and amino acid conjugates from each other, and from free IAA.

Journal Article↗