Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “INDOLEACETIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMed1994

The rhd6 Mutation of Arabidopsis thaliana Alters Root-Hair Initiation through an Auxin- and Ethylene-Associated Process.

Root-hair initiation in Arabidopsis thaliana provides a model for studying cell polarity and its role in plant morphogenesis. Root hairs normally emerge at the apical end of root epidermal cells, implying that these cells are polarized. We have identified a mutant, rhd6, that displays three defects: (a) a reduction in the number of root hairs, (b) an overall basal shift in the site of root-hair emergence, and (c) a relatively high frequency of epidermal cells with multiple root hairs. These defects implicate the RHD6 gene in root-hair initiation and indicate that RHD6 is normally associated with the establishment of, or response to, root epidermal cell polarity. Similar alterations in the site of root-hair emergence, although less extreme, were also discovered in roots of the auxin-, ethylene-, abscisic acid-resistant mutant axr2 and the ethylene-resistant mutant etr1. All three rhd6 mutant phenotypes were rescued when either auxin (indoleacetic acid) or an ethylene precursor (1-aminocyclopropane-1-carboxylic acid) was included in the growth medium. The rhd6 root phenotypes could be phenocopied by treating wild-type seedlings with an inhibitor of the ethylene pathway (aminoethoxyvinylglycine). These results indicate that RHD6 is normally involved in directing the selection or assembly of the root-hair initiation site through a process involving auxin and ethylene.

Journal Article↗
PubMed1970

The time course of xylem differentiation and its relation to deoxyribonucleic Acid synthesis in cultured coleus stem segments.

The relationship between DNA synthesis and wound xylem differentiation was investigated in cultured stem segments of Coleus blumei. The addition of 50 micrograms of indoleacetic acid per liter to the culture medium resulted in a 400 to 500% increase in the number of wound vessel members formed in 7 days. However, the time course of wound vessel member formation was similar in segments cultured in the presence and absence of auxin. In either case, no wound vessel members appeared before the 3rd day of culture, while the majority of wound vessel members appeared on the 4th and 5th days of culture. (3)H-Thymidine incorporation into DNA was used to measure changes in the DNA synthetic activity of the tissues during the culture period. Comparatively little (3)H-thymidine incorporation occurred during the 1st day of culture. Maximum (3)H-thymidine incorporation was observed on the 2nd day of culture, 2 days before the peak period of xylem differentiation. The rate of incorporation of (3)H-thymidine into DNA decreased with increasing time in culture after the 2nd day. Auxin at 50 micrograms per liter had no effect on the time course of (3)H-thymidine incorporation, although somewhat more (3)H-thymidine was incorporated into DNA throughout the culture period in the presence of auxin. The magnitude of this effect was small when compared to the effect of auxin on xylem differentiation. The antimetabolite 5-fluorodeoxyuridine was shown to block DNA synthesis in the cultured stem segments. When the tissues were isolated on media containing 10(-6)m 5-fluorodeoxyuridine, wound vessel member differentiation was inhibited by approximately 80%, in both the presence and absence of auxin. Thymidine at 10(-5)m completely overcame the 5-fluorodeoxyuridine inhibition of wound vessel member formation. 5-Fluorodeoxyuridine was effective in blocking xylogenesis only when this substance was supplied to the tissues during the early part of the culture period. 5-Fluorodeoxyuridine had no effect on xylem differentiation when it was applied after the 3rd day of culture.

Journal Article↗
PubMed1979

Indole-3-acetic Acid Oxidase from Peas: I. Occurrence and Distribution of Peroxidative and Nonperoxidative Forms.

Tissues of etiolated pea seedlings variety Alaska were examined for the presence of peroxidative and nonperoxidative forms of indoleacetic acid (IAA) oxidase. Enzymes were extracted in a sequence involving acetone powder preparation from pea tissues, buffer extraction of the powder, ammonium sulfate precipitation, dialysis, lyophilization, and acrylamide gel electrophoresis. Electrophoretically separable proteins were assayed for IAA oxidase activity with the Salkowski test, and peroxidase activity was based on the color reaction with benzidine and H(2)O(2). Each tissue examined contained several nonperoxidative IAA oxidases. No tissue contained more than three peroxidative IAA oxidases, whereas the plumule hooks (a tissue with a high IAA oxidase activity) contained no detectable peroxidases. The results indicate that nonperoxidative IAA oxidases might play a major role in the regulation of IAA content in pea seedlings.

Journal Article↗
PubMed1976

Determination of conjugated monoamine metabolites in brain tissue.

Levels of free and conjugated monoamine metabolites were analysed in brain tissue of rat and man. In the rat the conjugates were mainly of the sulfate ester type. The levels of conjugated dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) constituted 40--50% of the total amount of the metabolites. 4-Hydroxy-3-methoxy-phenylglycol (HMPG) and 5-hydroxy-3-indoleacetic acid (5-HIAA) were present as conjugates in 90 and 10% of the total levels. Chlorpromazine treatment resulted in an elevation of both the free and the conjugated forms of the dopamine metabolites and HMPG. In a human caudate nucleus obtained at autopsy both DOPAC and HMPG were present in the free form and as sulfate and glucuronide conjugates. The major dopamine metabolite found in this human brain was HVA. This metabolite and 5-HIAA occurred predominantly as free metabolites.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1993

The role of tryptophan, 5-hydroxy indole-3-acetic acid and their protein binding in uremic patients.

An on-line high performance liquid chromatography (HPLC) method of analysis with electrochemical detection was developed to quantitate catecholamines, tryptophan (Trp) and 5-hydroxy indoleacetic acid (5-HIAA) in muscle and plasma samples from healthy subjects and uraemic patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Equilibrium dialysis was performed on the plasma samples from 14 healthy and 14 uraemic subjects for the separation of free Trp and its metabolites from bound Trp. The results demonstrate abnormal Trp-albumin binding probably with accumulation of indolic metabolites and abnormally high muscle Trp concentration in uraemic patients.

Adult↗
PubMed2001

Chilling-induced leaf abscission of Ixora coccinea plants. III. Enhancement by high light via increased oxidative processes.

The role of increased oxidation induced by successive stresses of chilling and high light in the induction of leaf abscission was studied in Ixora coccinea plants in relation to auxin metabolism and oxidative processes. Exposure of plants following dark chilling (7 degrees C for 3 days) to high light (500-700 &mgr;mol m-2 s-1 photosynthetically active radiation) for 5 h at 20-25 degrees C enhanced chilling-induced leaf abscission. This abscission was inhibited by pretreatment with the antioxidant butylated hydroxyanisole, alpha-naphthaleneacetic acid or the ethylene action inhibitor, 1-methylcyclopropene. The oxidative processes initiated during the low light period following the dark chilling period, such as indoleacetic acid (IAA) decarboxylation and lipid peroxidation, were further enhanced by subsequent exposure to high light. Photoinhibition, expressed by the reduction of the chlorophyll fluorescence parameter Fv/Fm, was evident following exposure to high light, irrespective of the temperature of the pretreatment, but this reduction persisted only in chilled plants. This suggests that oxidative processes generated during and after the chilling period might have inhibited the recovery from photoinhibition. The chilling stress under darkness induced a 60% reduction in superoxide dismutase (SOD) activity and significant increases (130-600%) in the activities of several other antioxidative enzymes. These data suggest that the chilling-induced reduction in SOD activity may well be responsible for the increase in the oxidative stress induced by the subsequent light treatment, as expressed by the increased enzymatic activities. Taken together, this study provides further support for the involvement of oxidative processes in the events occurring in tissues exposed to sequential chilling and light stresses, leading to reduction in free IAA content in the abscission zone and to leaf abscission.

Journal Article↗
PubMed2003

Effects of 2 hrs. restraint stress on brain serotonin metabolism and memory in rats.

Stress is a non-specific response of body to any physiological and psychological demand. Studies on experimental animals show that uncontrollable stress situation produce neurochemical and behavioral deficits In the present study effects of 2 hrs. restraint stress were monitored on brain serotonin metabolism and memory in starved rats. An episode of 2 hrs. restraint stress exhibited a significant decrease in food intake as well as in growth rate in starved rats. The memory function was significantly enhanced following 2 hrs. restraint stress in starved rats. The concentration of Noradrenaline (NA) and Dihydroxyphenyl acetic acid (DOPAC) were increased in the brain while no effect of restraint stress was observed on brain Dopamine (DA) level. Brain levels of 5-hydroxy indoleacetic acid (5-HIAA) was significantly decreased in restraint rats. Tryptophan levels in brain as well as in plasma significantly decreased in starved rats following 2 hrs. restraint stress. The findings are explained in terms of enhanced memory function following restrained stress which may be associated with a decrease in serotonergic function in starved rats.

Journal Article↗
PubMed1971

Mechanism of Auxin-induced Ethylene Production.

Indoleacetic acid-induced ethylene production and growth in excised segments of etiolated pea shoots (Pisum sativum L. var. Alaska) parallels the free indoleacetic acid level in the tissue which in turn depends upon the rate of indoleacetic acid conjugation and decarboxylation. Both ethylene synthesis and growth require the presence of more than a threshold level of free endogenous indoleacetic acid, but in etiolated tissue the rate of ethylene production saturates at a high concentration and the rate of growth at a lower concentration of indoleacetic acid. Auxin stimulation of ethylene synthesis is not mediated by induction of peroxidase; to the contrary, the products of the auxin action which induce growth and ethylene synthesis are highly labile.

Journal Article↗
PubMed1973

The role of light and growth regulators in the opening of the dentaria petiolar hook.

The phenomenon of the etiolated hook is not restricted to the hypocotyl of the dicotyledenous plant (e.g., Phaseolus) but appears to serve a similar, adaptive function in the petioles of certain rhizomatous plants. The commonly employed regulants of hypocotyl hook opening were tested for their effect on the petiolar hook of Dentaria diphylla. The hook was found to require both light (red light promoted, far red inhibited) and the intact leaf for opening. The leaf requirement was fully replaced by gibberellic acid (0.04% in lanolin) but only in light; cobalt chloride (0.1-1.0 mm) promoted a partial opening in dark with or without leaf; and coumarin (1 mm), indoleacetic acid (1-4% in lanolin), and ethylene 10 microliter per liter all inhibited opening of hooks with or without lamina. The absolute requirement for light and leaf tissue and the replacement of proximal tissue by GA(3) alone represent marked differences in the physiology of hypocotyl and petiolar hooks. These differences are believed to indicate the necessity for concomitant leaf maturation in petiolar hook opening.

Journal Article↗
PubMed1977

Emergent growth: an auxin-mediated response.

Restoration of oxygenated conditions following 15 minutes to 2 hours of anoxia causes light-grown pea (Pisum sativum L. var. Alaska) stem segments to elongate 100 to 200% more than continuously aerated segments. This "emergent growth" response takes place in the presence of 5 mm F(-), an inhibitor of anaerobic respiration; therefore, a build-up of glycolytic products does not appear to be the mechanism underlying emergent growth. "Acid growth" does not appear to account directly for the hyperelongation, as extracellular pH does not drop following a return to aerobic conditions. Studies with (14)C-indoleacetic acid indicate that auxin is freed from some previously unavailable pool during O(2)-limited treatments. We suggest, therefore, that emergent growth is a response to auxin which is released during anaerobiosis: the newly mobile or diffusible auxin promoting growth when O(2) is no longer limiting.

Journal Article↗
PubMed1996

Inhibition of glucose uptake by 5-hydroxyindoleacetic acid in the isolated rat soleus muscle.

Accumulated end-products were identified to participate in the late development of glucose intolerance and insulin resistance (IR) in patients with chronic renal insufficiency. The possible pathophysiological role of accumulated 5-hydroxy-indoleacetic acid (5HIAA) in the genesis of IR was investigated employing an in vitro animal model. 5HIAA inhibited the basal glucose uptake in isolated rat soleus muscle with intact membrane with A50 = 1.25 mumol/l, and Emax = 88.6%. 5HIAA significantly inhibited the insulin, and tolbutamide stimulated glucose uptake. In Ca and Mg depletion 5HIAA showed a partially additive inhibitory effect, while nonadditive inhibitory activity was observed in the case of K+ excess. It is concluded that 5HIAA is a metabolically active end-product interfering with glucose uptake in muscle at an insulin postreceptor level, and its effect is related to Ca modulation in the insulin regulatory cascade.

Animals↗
PubMed1972

Involvement of Peroxidase and Indole-3-acetic Acid Oxidase Isozymes from Pear, Tomato, and Blueberry Fruit in Ripening.

Protein extracts were obtained from climacteric fruits (pear, tomato) and nonclimacteric fruits (blueberry) during various stages of ripening. The use of a gel electrophoresis technique revealed a consistent reinforcement in indoleacetic acid oxidase but not in peroxidase isozymes during ripening. The significance of the results is discussed in relation to the resistance of fruits to ripening and ethylene action.

Journal Article↗
PubMed2004

Effects of chronic ethanol treatment on monoamine levels in rat hippocampus and striatum.

We studied the effects of ethanol on concentrations of noradrenaline (NE), dopamine (DA) and serotonin (5-HT) and their metabolites in rat hippocampus and striatum. Ethanol (2 or 4 g/kg, po, from a 20% aqueous solution) was administered daily to male Wistar rats (4-13 per group) for 30 days and animals were sacrificed 30 min or 48 h after the last administration. Monoamines were measured by HPLC and considered significant at P < 0.05. A 47% increase in 5-HT levels was observed in the hippocampus with 4 g/kg ethanol in the 30-min protocol. Ethanol (2 and 4 g/kg) decreased DA (2114.5 +/- 126.4 and 1785.1 +/- 234.2 ng/g wet tissue, respectively) and 3,4-dihydroxyphenylacetic acid (DOPAC, 1477.6 +/- 132.1 and 1218.8 +/- 271.7 ng/g wet tissue, respectively) levels, while the higher dose also decreased NE (159.8 +/- 13.5), 5-HT (228.0 +/- 46.8) and 5-hydroxy-3-indoleacetic acid (5-HIAA, 304.4 +/- 37.2 ng/g wet tissue), in the striatum after a 48-h withdrawal as compared to controls (DA: 3063.9 +/- 321.3; DOPAC: 2379.6 +/- 256.0; NE: 292.8 +/- 50.2; 5-HT: 412.4 +/- 36.2; 5-HIAA: 703.9 +/- 61.4 ng/g wet tissue). In the 30-min protocol, ethanol (2 or 4 g/kg) decreased striatal NE (66 and 70%) and DA (50 and 36%) levels. On the other hand, increases were seen in 5-HIAA (146 and 153%) and 5-HT (59 and 86%) levels. Ethanol (2 g/kg, po) increased the homovanillic acid (HVA)/DA ratio (129%) in the striatum in the 30-min protocol, while at the higher dose it increased the HVA/DA ratio in the 48-h protocol (61%). These results indicate alterations in monoamines, mainly in the striatum, after chronic ethanol, which are influenced by dose and by the length of time after the last drug administration.

Animals↗
PubMed2004

Endogenous and dietary indoles: a class of antioxidants and radical scavengers in the ABTS assay.

Indoles are very common in the body and diet and participate in many biochemical processes. A total of twenty-nine indoles and analogs were examined for their properties as antioxidants and radical scavengers against 2,2'-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) ABTS*+ radical cation. With only a few exceptions, indoles reacted nonspecifically and quenched this radical at physiological pH affording ABTS. Indoleamines like tryptamine, serotonin and methoxytryptamine, neurohormones (melatonin), phytohormones (indoleacetic acid and indolepropionic acid), indoleamino acids like L-tryptophan and derivatives (N-acetyltryptophan, L-abrine, tryptophan ethyl ester), indolealcohols (tryptophol and indole-3-carbinol), short peptides containing tryptophan, and tetrahydro-beta-carboline (pyridoindole) alkaloids like the pineal gland compound pinoline, acted as radical scavengers and antioxidants in an ABTS assay-measuring total antioxidant activity. Their trolox equivalent antioxidant capacity (TEAC) values ranged from 0.66 to 3.9 mM, usually higher than that for Trolox and ascorbic acid (1 mM). The highest antioxidant values were determined for melatonin, 5-hydroxytryptophan, trp-trp and 5-methoxytryptamine. Active indole compounds were consumed during the reaction with ABTS*+ and some tetrahydropyrido indoles (e.g. harmaline and 1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid ethyl ester) afforded the corresponding fully aromatic beta-carbolines (pyridoindoles), that did not scavenge ABTS*+. Radical scavenger activity of indoles against ABTS*+ was higher at physiological pH than at low pH. These results point out to structural compounds with an indole moiety as a class of radical scavengers and antioxidants. This activity could be of biological significance given the physiological concentrations and body distribution of some indoles.

Antioxidants↗
PubMed1977

Dormancy and Impotency of Cocklebur Seeds: IV. Effects of Gibberellic Acid, Benzyladenine, Thiourea, and Potassium Nitrate on the Growth of Embryonic Axis and Cotyledon Segments.

Germination of nondormant but impotent small cocklebur seeds (Xanthium pennsylvanicum Wallr.) was promoted profoundly with thiourea or benzyladenine, and slightly with gibberellic acid. Gibberellic acid was ineffective in causing the germination of dormant cocklebur seeds, although thiourea and benzyladenine were effective. Experiments with excised seed pieces showed that the promotive effects of thiourea, benzyladenine, and gibberellic acid on cocklebur seed germination were associated with the enhancement of growth of seed parts; thiourea stimulated predominantly the axial growth, whereas benzyladenine stimulated predominantly the cotyledonary growth.Potassium nitrate or indoleacetic acid had little effect on the initial growth of either axes or cotyledons. Except for gibberellic acid, all of the compounds employed enhanced ethylene production, but in general, the ethylene production seemed more likely to be a consequence of growth rather than a cause of it. We concluded that the chemical regulation of seed germination may be a consequence of the alteration of growth capabilities in either the axes or cotyledons, or both.

Journal Article↗
PubMed1966

Vascular Regeneration and Long Distance Transport of Indole-3-acetic Acid in Coleus Stems.

Excision of all leaves and buds of Coleus blumei Benth. plants reduced xylem cell and sieve tube regeneration a highly significant amount around a wound in internode number 5 when compared with regeneration in intact (wounded) plants. Application of indoleacetic acid (IAA-(14)C) to the cut surface of internode number 2 restores regenerative activity around the wound in internode number 5. Radioactivity applied as IAA-(14)C reaches the wound area when applied at the cut surface of inter-node number 2 showing a logarithmic decrease with distance from the point of application. Chromatography showed that radioactivity was located close to the R(F) of IAA as well as near the solvent front.Addition of gibberellic acid to IAA-(14)C did not change the pattern of radioactivity throughout the stem.

Journal Article↗
PubMed1967

Studies on the oxidation of indole-3-acetic Acid by peroxidase enzymes. I. Colorimetric determination of indole-3-acetic Acid oxidation products.

The method described here is based on a brief report by Harley-Mason and Archer. It involves the use of p-dimethylaminocinnamaldehyde (DMACA), a vinylogue of Ehrlich's reagent, as a color reagent for indoles. Colorimetric analyses of indoleacetic acid (IAA) oxidation reaction mixtures were made with the DMACA reagent as a solution rather than a spray. DMACA reagent will yield a wine-red color with IAA oxidation products in solution. Under similar conditions DMACA reacts with authentic IAA to yield only slight coloration at best. In comparison with other indoles, DMACA is more relative with IAA oxidation reaction products than either Salkowski or Ehrlich's reagents. Data discussed support a concept that the color produced with DMACA is due to the presence of tautomeric oxidation product(s) of IAA.

Journal Article↗
PubMed2005

Aromatic l-aminoacid decarboxylase deficiency: unusual neonatal presentation and additional findings in organic acid analysis.

Aromatic l-aminoacid decarboxylase (AADC) deficiency is a neurotransmitter defect leading to a combined deficiency of catecholamines and serotonin. Patients are usually detected in infancy due to developmental delay, hypotonia, and extrapyramidal movements. Diagnosis is based on an abnormal neurotransmitter metabolite profile in CSF and reduced AADC activity in plasma. An elevation of vanillactic acid (VLA) has been described as the only abnormality detected in organic acid analysis (OA) of urine. We report a patient who presented in the neonatal period with lethargy, hypotonia, metabolic acidosis, and hypoglycemia. Blood ammonia, lactic acid, and acylcarnitines were normal, but OA of a urine sample showed a small increase of VLA, raising the suspicion of AADC deficiency. The patient was lost to follow-up until the age of 8 months, when he presented with dystonia, abnormal movements, oculogyric crises, and hypothermia. Repeat OA showed not only increased levels of VLA, but also increased vanilpyruvic acid (VPA), N-acetyl-vanilalanine (AVA) and N-acetyl-tyrosine (NAT). Neurotransmitter analysis in CSF showed increased vanilalanine (1200 nmol/L, ref<100) with decreased levels of 5-hydroxy-indoleacetic acid (5-HIAA, < 5 nmol/L; ref 152-462), homovanillic acid (HVA, 83 nmol/L; ref 302-845), and methoxy-hydroxy-phenyl-glycol (<5 nmol/L; ref 51-112). AADC activity in plasma was nearly undetectable. In the urine, low excretion of vanilmandelic acid (<0.3 micromol/mmol creat; ref 0.3-20) and 5-HIAA (0.9 micromol/mmol creat; ref 4-18), was found, but HVA was normal and dopamine even elevated. This contradictory phenomenon of hyperdopaminuria has been described earlier in AADC deficient patients. We postulate that VPA and AVA could originate from vanilalanine (through a transaminase and an acetylase respectively), while NAT could originate from tyrosine through an AA acetylase. This report expands the clinical presentation of AADC deficiency and adds new markers of the disease for OA analysis, improving detection of AADC deficient patients in general metabolic screening procedures.

Aromatic-L-Amino-Acid Decarboxylases↗