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Occupational exposure to urban pollutants and urinary 5-hydroxy-3-indoleacetic acid.

According to the literature, various occupational and environmental stressors may cause alterations in serotonin (5-HT) turnover and in its principal metabolite, 5-hydroxy-3-indoleacetic acid (5-HIAA). The aim of this study is to evaluate whether traffic police exposed to urban pollutants and possible psycho-social stressors could be at risk of alterations in urinary 5-HIAA in 24 hours (5-HIAA[U]) compared with a control group. After the main non-occupational confounding factors were excluded, 5-HIAA(U) excretion was investigated in 140 employees of a municipal police force: 70 traffic police with outdoor activity that exposed them to urban pollutants and 70 administrative workers with indoor activity. Subjects were matched by sex, age, and length of working life. The mean 5-HIAA(U) levels were significantly lower in traffic police than in administrative workers, both males and females (p = .025, and p = .027, respectively), matching modifications in 5-HIAA(U) levels found by other authors in studies on animals and human subjects.

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PubMed1977

Uptake and Growth-promoting Activity of Indoleacetic Acid in Segments of Cold-hardened Wheat Coleoptiles.

Seedings of winter wheat (Triticum aestivum L. cv. Kharkov MC 22) were grown at 24 C (unhardened) and 4 C (hardened). Indoleacetic acid (IAA) was added to excised coleoptile segments after lengthy incubation and their responses were determined by photometric auxanometry at both 25 C and 5 C. The segments' rates of uptake of (14)CIAA were also compared at both temperatures. Cold hardening had no significant effect on the rates of elongation and uptake in a saturating concentration of IAA (2 to 10 muM) at either temperature. Elongation was more sensitive to temperature of measurement than was uptake. At suboptimal concentrations of IAA and 25 C, hardened coleoptiles took up [2-(14)C]-IAA twice as fast but elongated half as fast as unhardened coleoptiles. This and the lack of effect of cold hardening on apparent uptake of [1-(14)C]-IAA raised the possibility that a higher rate of IAA-decarboxylation was coupled with the higher rate of uptake of IAA by hardened coleoptiles. Homeostatic hormonal regulation was also evident in the same endogenous rates of elongation of segments of cold-hardened and unhardened coleoptiles.

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PubMed1970

Inhibitors from Carob (Ceratonia siliqua L.): II. Effect on Growth Induced by Indoleacetic Acid or Gibberellins A(1), A(4), A(5), and A(7).

Two inhibitory fractions (B(1) and C) from extracts of immature fruit of carob were tested for their ability to inhibit the action of indoleacetic acid (IAA) in three bioassays. There was no reduction of IAA-induced reactions in the Avena curvature test, abscission of debladed coleus petioles, or growth of cucumber hypocotyls. The highest ratio of inhibitor to IAA was 10,000 times greater than the ratio necessary to inhibit by 50% the growth caused by an equivalent amount of gibberellin A(3) in pea seedlings. At the highest concentration used, fraction C alone caused curvature of Avena coleoptiles. The inhibitory fractions appeared to enhance the effect of IAA in the cucumber test.Concentrated whole extract and fractions B(1) and C were tested for reduction of growth caused by gibberellins A(1), A(4), A(5), A(7), and a neutral gibberellin-like substance from beans in the dwarf-5 maize bioassay. Each gibberellin was inhibited and required the same amount of inhibitor for a 50% reduction of the induced growth. The inhibiting effect could be completely overcome by increasing the amount of gibberellin while maintaining the same concentration of inhibitor. Fractions B(1) and C were also tested with gibberellins A(2) and A(4) in the cucumber hypocotyl test. Both inhibitory fractions reduced growth but were more effective against gibberellin A(3) than gibberellin A(4) in the assay. The ability to reduce gibberellin-induced growth and not reduce IAA-induced growth indicates that the inhibitors from carob have a greater specificity of action than that previously reported for any inhibitor.

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PubMed1986

A Possible Role for Indoleacetic Acid, Low Temperature, and Phospholipid Metabolism in the Induction of GA(3) Responsiveness in GA(3) Insensitive (Rht3-Containing) Dwarf Wheat Aleurone.

Preincubation of dwarf, Rht3-containing deembryonated seed for 4 hours in 342 nanomolar indoleacetic acid (IAA) induced maximum sensitivity to GA(3). In addition, the 4-hour IAA pretreatment caused a 2-fold increase in total phospholipids which coincided identically on a temporal basis with the induced GA(3) sensitivity. Changes in absolute levels of individual phospholipids and their acyl groups were recorded and compared with the changes observed in several Rht-containing aleurone tissues which were induced to develop GA(3) sensitivity by exposure to low temperature (5 degrees C). Several distinct similarities between all tissues were recorded as they develop GA(3) sensitivity. One parameter, the percentage phospholipid composition, was quite similar in all tissues after they had become maximally sensitive to GA(3), suggesting that there is at least one membrane phospholipid composition which is particularly responsive to GA(3). The results indicate that (a) the basis of the GA(3) insensitivity of the Rht mutation resides in an aberrant phospholipid/fatty acid composition and/or metabolism; (b) exposure to low temperature (5 degrees C) for 20 hours or longer, or 342 nanomolar IAA for 4 hours or longer reverses or corrects the genetic lesion, enabling the tissue to adopt a GA(3) responsive membrane composition. Finally, an hypothesis is discussed which indicates that IAA may play a controlling role in the mobilization of endospermal reserves, at least in Rht3-containing wheat aleurone.

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PubMed1991

Evidence of zein-bound indoleacetic Acid using gas chromatography-selected ion monitoring-mass spectrometry analysis and immunogold labeling.

Commercial zein was base-hydrolyzed and purified extracts were subjected to gas chromatography-selected ion monitoring-mass spectrometry analysis. Indoleacetic acid (IAA) was shown to be released from this storage protein of corn (Zea mays). Isotope dilution using [(13)C(6)]IAA as an internal standard revealed a conservative ratio of 1 mole IAA to 175 moles zein. Immunoelectron micrographs of isolated protein bodies also showed IAA or an IAA-like molecule associated with zein and deposited within these organelles.

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PubMed1988

Effect of Indoleacetic Acid- and Fusicoccin-Stimulated Proton Extrusion on Internal pH of Pea Internode Cells.

Using (31)P nuclear magnetic resonance spectroscopy, we followed cytoplasmic and vacuolar pH in pea (Pisum sativum cv Alaska) internode segments during treatment with indoleacetic acid (IAA) or fusicoccin (FC) in continuously perfused, oxygenated buffer. Although IAA and FC induced normal H(+) extrusion, elongation, and glucan synthase activity responses during the measurements, neither the cytoplasmic nor the vacuolar pH showed significant change at any time between 5 minutes and 1 to 3 hours of treatment. Changes in cytoplasmic pH as small as about 0.04 pH unit were detected after treatment with 1-naphthyl acetate. Therefore, cytoplasmic pH changes do not appear to mediate IAA or FC stimulation of H(+) extrusion or other metabolic responses to these effectors.

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PubMed1981

Role of indoleacetic Acid and abscisic Acid in the correlative control by fruits of axillary bud development and leaf senescence.

When fully filled pods of bean plants were deseeded, the rate of axillary bud growth and the chlorophyll content of leaves were increased. Application of 0.1% indoleacetic acid (IAA) in lanolin on the deseeded pods caused abscission of axillary buds, inhibited growth of the remaining buds, and decreased leaf chlorophyll content. The response of bud development to fruit-applied IAA was concentration dependent between 0.001 and 0.1% IAA (representing from 2 to 200 micrograms IAA per fruit) resulting in greater growth inhibition at higher IAA concentrations.When plants were defruited so that the number of fruits per plant was adjusted to 0, 6, 12, or 18, a dosage effect of fruits on photosynthesis was observed. Removal of all fruits caused a rise in the CO(2)-exchange rate (CER). With increasing fruit dosage, plants showed leaf senescence of increasing intensity and a corresponding decline in CER. In contrast to the effect of fruit-applied IAA on leaves and buds, it delayed the senescence of treated fruits. When axillary buds were treated directly with aqueous solutions of IAA, no growth inhibition occurred.Abscisic acid (AbA) applied on deseeded pods, up to a concentration of 0.1% AbA in lanolin, failed to inhibit axillary bud development or to cause leaf senescence.The results support the hypothesis that the correlative control of axillary bud development and leaf senescence by fruits involves the participation of both IAA and AbA. IAA, released by the seeds, may play the role of the correlative signal that moves from the fruit to the target organ, where it stimulates the synthesis or accumulation of AbA. AbA, in turn, may be responsible for the inhibition of axillary bud development and the enhancement of leaf senescence.

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PubMed1977

Effects of Indoleacetic Acid on the Quantity of Mitochondria, Microbodies, and Plastids in the Apical and Expanding Cells of Dark-grown Oat Coleoptiles.

We determined the number of mitochondria, microbodies, and plastids in dark-grown oat (Avena sativa) coleoptiles following incubation in indoleacetic acid (IAA) for a period of 60 minutes at 6-minute intervals. In the apical outer epidermis of coleoptiles, the mitochondria increased from 31.4 to 35 per cell section with a 6-minute incubation in IAA, and this trend persisted over the 60-minute incubation. Neither the microbodies, plastids, nor the dicytosomes (Gawlik and Miller 1974 Plant Physiol 54:217-221) responded to the hormone. The apical parenchyma showed no change in quantity of any of the organelles including the dictyosomes during IAA incubation. The quick response of mitochondria in the coleoptile tip could be interpreted as an association of this organelle with hormone transport, growth, or perhaps with gravity perception. In the subapical expansion region, IAA caused significant reductions of mitochondria, microbodies, and dictyosomes in the outer epidermis compared to the control, the timing of which preceded the IAA-induced elongation and of geotropism. The fast response of organelles in the various cells is probably a change in organelle volume rather than number. That microbodies show a response to the plant hormone in the permanently achlorophyllous epidermis indicates that these organelles, in addition to their peroxisomal functions in green leaves, also may have a growth regulation function. IAA treatment was without effect on the quantity of the various types of plastids (including the amyloplasts) in the different oat coleoptile cells.

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PubMed1981

Some aspects of the control of root growth and georeaction: the involvement of indoleacetic Acid and abscisic Acid.

Apical segments of roots of Zea mays L. cv. Orla and cv. Anjou show a strong georeaction during 7 hours geostimulation. This is abolished by detipping the segments and restored by replacing the tips upon the apical cut surfaces. After exodiffusion of endogenous indoleacetic acid (IAA) the retipped segments showed a significantly lower geocurvature. Application of low concentrations of IAA to the basal cut surface of root segments from which endogenous IAA had not been allowed to exodiffuse increased the geocurvature of retipped Orla segments but decreased geocurvature of Anjou segments. At appropriate concentration basally applied IAA restored the georeaction capacity of root segments from which the endogenous auxin had exodiffused. The implications of the interaction between exogenous and endogenous IAA in the control of root georeaction are discussed with special reference to the normal role of endogenous IAA in the regulation of root georeaction and the variation in endogenous IAA content of roots of different cultivars of maize. The probability that the normal control of root growth and georeaction involves concomitant actions in the elongation zone of IAA moving preferentially in the acropetal direction and basipetally transported growth inhibitors (such as abscisic acid) produced in the cap cells is stressed.

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PubMed1974

A Synergistic Stimulation of Avena sativa Coleoptile Elongation by Indoleacetic Acid and Carbon Dioxide.

The ability of 0.03% CO(2) to stimulate growth has been investigated using etiolated Avena coleoptile sections maintained in buffered solution. This concentration of CO(2)-stimulated growth after a lag period of 12 to 15 minutes, and a synergistic relationship between indoleacetic acid and CO(2) in stimulating growth has been demonstrated. The response to CO(2) is inhibited by cycloheximide and is lost approximately 10 minutes after exposure to CO(2)-free air. Malate can replace CO(2) in stimulating growth. In the light of these data and recent literature on a growth response of coleoptile sections to CO(2)-saturated solutions, the existence of two mechanisms of CO(2)-simulated growth is proposed. In addition, it is suggested that growth promotion by 0.03% CO(2) is mediated by a process involving dark CO(2) fixation.

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PubMed1974

Effects of indoleacetic Acid on dictyosomes of apical and expanding cells of oat coleoptiles.

We found that the auxin-induced growth is mediated through the activation of the dictyosomes (collectively, the Golgi apparatus). Incubation of oat (Avena sativa) coleoptile segments in indoleacetic acid-sucrose-phosphate buffer changes significantly the number of dictyosomes in the expanding cells. A further indication of auxin enhancement of dictyosome activity is a decrease in dictyosomal cisternae (flattened membranous sacs) number. This decrease occurred after 6 minutes of incubation in auxin, and then was followed by a reduction in the organelle number per se. These times are in keeping with the rapid action of auxin-induced cell elongaton, and the latent period of geotropism. In the apical cells, the effect of indoleacetic acid is more subtle and complex. The periods of increased dictyosome utilization and of increased dictyosome synthesis in auxin-treated segments alter with those of the control. These observations indicate that dictyosomes not only have a function in cell elongation, but also may participate in processes such as auxin transport and stimuli perception. The expanding cells have five times as many dictyosomes as the cells in the apex. Dictyosome number within a cell appears to be directly proportional to the length of the cell. The fluctuation of dictyosome number and the effect of auxin on the rate of elongation of individual outer epidermis are discussed.

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PubMed1992

Transgenic Tobacco Plants Coexpressing the Agrobacterium tumefaciens iaaM and iaaH Genes Display Altered Growth and Indoleacetic Acid Metabolism.

Transgenic tobacco (Nicotiana tabacum) SR1 plants expressing the Agrobacterium tumefaciens nopaline transferred DNA iaaH gene were transformed with a 35S-iaaM construct. The transformants displayed several morphological aberrations, such as adventitious root formation on stem and leaves, dwarfism, epinastic leaf growth, increased apical dominance, and an overall retardation in development. In addition, xylem lignification was higher than in wild type. Free and conjugated indoleacetic acid (IAA) levels were quantified by gas chromatography-multiple ion monitoring-mass spectrometry in leaves and internodes of wild-type plants and two transformed lines with different phenotypes. Both transformed lines contained elevated levels of free and conjugated IAA, which was associated with increased transcription of the iaaM gene. The line with the highest IAA level also had the most altered pattern of growth and development. These IAA-overproducing plants will provide a model system for studies on IAA metabolism, IAA interactions with other phytohormones, and IAA roles in regulating plant growth and development.

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PubMed1972

Comparison of zeatin indoleacetate with zeatin and indoleacetic Acid in the tobacco bioassay.

Zeatin indole-3-acetate, 6-[4-(indole-3-acetoxy)-3-methyl-trans-2-butenylamino]purine, is at least as effective as zeatin on a molar basis in satisfying the cytokinin requirement for growth and bud formation in tobacco bioassays. It is less effective than indole-3-acetic acid and is needed as a variable function of the cytokinin concentration for satisfying the optimal requirement of an auxin. Comparisons of the types of growth and yield of tissue obtained with serial concentration of the ester and with equimolar mixtures of its free base and acid indicate that the relative requirement for auxin changes with the concentration of cytokinin and is related to the types of callus growth and differentiation which occur. The results also suggest that the ester serves as a source of auxin only after modification, presumably by hydrolysis to indoleacetic acid.

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PubMed1991

Free and Conjugated Indoleacetic Acid (IAA) Contents in Transgenic Tobacco Plants Expressing the iaaM and iaaH IAA Biosynthesis Genes from Agrobacterium tumefaciens.

The Agrobacterium tumefaciens T-DNA gene iaaM was introduced by leaf-disc transformation into transgenic tobacco (Nicotiana tabacum) plants expressing the iaaH gene. Regenerated calli were screened for the presence of indole-3-acetamide (IAM), by gas chromatography-multiple ion monitoring-mass spectrometry, and IAM-containing calli were further analyzed for free and conjugated indoleacetic acid (IAA). It was found that transgenic calli on average contained twice as much free IAA and three times more conjugated IAA than calli from wild-type plants. About 40% of the transformed calli could be regenerated to plants. The distribution of free and conjugated IAA was measured in transformed plants with a normal phenotype and compared with equivalent wild-type plants. The IAA content of transgenic plants was only slightly increased, whereas IAA-conjugate levels were enhanced significantly. These data suggest that conjugation of IAA may serve as a regulatory mechanism, contributing to maintenance of steady-state IAA pool sizes during tobacco growth and development.

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PubMed1998

The characterization of gio, a new pea mutant, shows the role of indoleacetic acid in the control of fruit development by the apical shoot.

Fruit-set and fruit growth in pea (Pisum sativum L.) depend on gibberellins (GAs). The authors have isolated a new pea mutant, gio, which appeared spontaneously within the population of the cultivar Alaska, characterized by unpollinated ovaries much less sensitive to applied GAs. The mutant also has elongated peduncles, and is taller than the wild-type (WT) because the upper plant internodes are longer. Contrary to WT, the gio ovaries respond very little to benzylaminopurine (BAP) and 2,4-dichlorophenoxyacetic acid, but become fully sensitive to GA(3) when this hormone is applied together with BAP. The gio phenotype is determined by a mutation at a single mendelian locus. The mutation is recesive, shows incomplete penetrance, and its expression depends on environmental culture conditions. The sensitivity of the ovaries to GA(3) can be recovered by removing the apical shoot (plant decapitation) and by blocking the transport of indoleacetic acid (IAA) from the apical shoot with 2,3,5-triiodobenzoic acid. The content of IAA in methanolic extracts and phloematic exudates of the apical shoot of gio is about double that in the WT. The rate of transport of [(3)H]IAA applied to the apex of the mutant is also twice that in the WT. This indicates that the insensitivity of the gio ovaries to GAs is due to the inhibitory effect of the higher basipetal IAA transport from the shoot. The interaction between the fruit and the apical shoot mediated by IAA probably also involves cytokinins transported from the basal part of the plant.

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PubMed1990

In vitro oxidation of indoleacetic Acid by soluble auxin-oxidases and peroxidases from maize roots.

Soluble auxin-oxidases were extracted from Zea mays L. cv LG11 apical root segments and partially separated from peroxidases (EC 1.11.1.7) by size-exclusion chromatography. Auxin-oxidases were resolved into one main peak corresponding to a molecular mass of 32.5 kilodaltons and a minor peak at 54.5 kilodaltons. Peroxidases were separated into at least four peaks, with molecular masses from 32.5 to 78 kilodaltons. In vitro activity of indoleacetic acid-oxidases was dependent on the presence of MnCl(2) and p-coumaric acid. Compound(s) present in the crude extract and several synthetic auxin transport inhibitors (including 2,3,5-triiodobenzoic acid and N-1-naphthylphthalamic acid) inhibited auxin-oxidase activity, but had no effect on peroxidases. The products resulting from the in vitro enzymatic oxidation of [(3)H] indoleacetic acid were separated by HPLC and the major metabolite was found to cochromatograph with indol-3yl-methanol.

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