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PubMed1996

1-(4-iodobenzoyl)-5-methoxy-2-methyl-3-indoleacetic acid, an iodinated indomethacin analog.

The crystal structure of 1-(4-iodobenzoyl)-5-methoxy-2-methyl-3-indoleacetic acid, C19H16INO4, an analog of indomethacin, is reported. Bond distances and angles in the title compound closely resemble those reported for indomethacin and reflect the presence of steric strain at the site of the linkage between the 4-iodobenzoyl group and the indole moiety. The orientation of the 4-iodobenzoyl group with respect to the indole ring is not the same in the title compound as it is in indomethacin; the two structures are related by a rotation of 186 degrees about the C2--N1--C10--C11 torsion angle.

Crystallography, X-Ray↗
PubMed1975

Hormone receptor studies on frog macrophage cells by means of histamine, serotonin and indoleacetic acid.

The phagocytotic activity of frog macrophage cells could be increased by 50% with histamine and by 24% with serotonin. These hormones have a similar effect at the various stages of phylogenetic development, to judge from the respective responses of the unicellular Tetrahymena which showed roughly the same percentual increases of phagocytosis as frog macrophages at roughly the same hormone concentrations. It is concluded that cytoplasmic membrane receptor patterns for a given function do not change in the course of phylogenetic development and the receptors have a capacity for selection, preferring histamine to serotonin, and the latter to the chemically closely related plant hormone indoleacetic acid.

Animals↗
PubMed1966

Effect of manganese toxicity on the indoleacetic Acid oxidase system of cotton.

The effect of substrate manganese on tissue manganese levels and activity of the indoleacetic acid (IAA)-oxidase system of cotton (Gossypium hirsutum, L.) was investigated. A sand culture technique was used with 1, 3, 9, 27 and 81 mg manganese (MnSO(4)) per liter nutrient solution applied in various experiments.The following relationships held for both long-term (126 days) and short-term (12-14 days) exposures to manganese treatment: A) There was a direct relationship between substrate and tissue manganese. B) Only the 81 mg/liter Mn plants exhibited severe manganese toxicity symptoms. C) At the toxic level of manganese an increased IAA-oxidase activity and decreased IAA-oxidase inhibitor activity was observed. There was a direct relationship between degree of enzyme response and severity of visible symptoms. D) With the manganese toxicity plants, but none of the other treatments, extracts of the young leaves contained as much IAA-oxidase activity as extracts of much older leaves. E) Crude extracts from the plants grown with 81 mg manganese per liter solution, in contrast to those of other treatments, destroyed IAA without addition of MnCl(2) to the assay medium.A hypothesis is advanced stating that manganese toxicity symptoms in cotton are expressions of auxin deficiency caused by IAA-oxidase activity increased by the abnormal tissue levels of manganese.

Journal Article↗
PubMed1991

Rapid in situ assay for indoleacetic Acid production by bacteria immobilized on a nitrocellulose membrane.

We have developed a new assay that differentiates between indoleacetic acid (IAA)-producing and -nonproducing bacteria on a colony plate lift. Medium supplemented with 5 mM L-tryptophan is inoculated with isolates of interest, overlaid with a nitrocellulose membrane, and then incubated until bacterial colonies reach 1 to 2 mm in diameter. The membrane is removed to a filter paper saturated with Salkowski reagent and incubated until distinct red haloes form around the colonies. The colorimetric reaction to IAA is limited to a region immediately surrounding each colony, is specific to isolates producing IAA, occurs within 1 h after the membrane is placed in the reagent, and is sensitive to as little as 50 pmol of IAA in a 2-mm spot. We have used this assay for quantifying epiphytic and endophytic populations of IAA-producing isolates of Pseudomonas syringae subsp. savastanoi and for detecting IAA-producing colonies of other pseudomonads and Erwinia herbicola. The assay provides a rapid and convenient method to screen large numbers of bacteria.

Journal Article↗
PubMed1980

Liquid-chromatographic separation of urinary 5-hydroxy-3-indoleacetic acid, with measurement at 254 nm.

A "high-performance" liquid-chromatographic procedure for 5-hydroxy-3-indoleacetic acid is described and compared with a colorimetric method in which 1-nitroso-2-naphthol is used. The analyte and an internal standard, p-nitrobenzoic acid, were extracted into diethyl ether from urine at pH 4.0 (acidified with HCl) to which sodium chloride had been added, and the ether was back-extracted with acetate buffer, pH 9.2. Aliquots of this extract were injected into a reversed-phase liquid-chromatographic column and eluted with pH 3.5 acetate buffer/methanol (95/5 by vol); the effluent was monitored at 254 nm. The precision (CV) of the method was 11.8% at 1.8 mg/L, 5.5% at 92 mg/L. Analytical recovery averaged 84%. The colorimetric method gave higher values for the analyte than did the chromatographic method for all patients' urines.

Chromatography, High Pressure Liquid↗
PubMed1976

Indoleacetic Acid synthesis in soybean cotyledon callus tissue.

Growth of an auxin-requiring soybean cotyledon callus tissue (Glycine max L., Merr. var. Acme) was promoted by tryptophan, tryptamine, indole, indoleacetamide and, to a very slight degree, anthranilic acid. When tryptophan-3-(14)C was supplied in the growth medium, labeled indoleacetic acid (IAA) was found in both the tissue and the medium. Medium, from which the cells had been removed, was also found to convert labeled tryptophan to IAA. Soybean callus contained 0.044 mumole/g free tryptophan, but this is apparently not available for conversion to IAA. These results suggest that while exogenously supplied trytophan could elevate a specific internal pool where IAA synthesis occurs some of the growth on a tryptophan medium can be accounted for by external conversion.

Journal Article↗
PubMed1968

Interactions of indoleacetic Acid and gibberellic Acid in leaf abscission control.

Debladed midribs of citrus leaves showed the typical delay of abscission in response to indoleacetic acid (IAA), and the typical acceleration of abscission in response to gibberellic acid (GA). Interaction experiments with these 2 hormones indicated that the balance of the 2 hormones may be more important in regulating abscission than the quantity of either. The often reported acceleration of abscission with low quantities of IAA did not seem to exist in citrus. IAA did accelerate abscission in this tissue when its application was delayed for at least 24 hours after deblading, which suggests the 2-stage effect is also present in citrus.When abscission was first delayed with IAA and then allowed to continue, the rate of abscission proceeded at a slower rate than was typical for this tissue. This slower rate was also typical of the effect observed when GA overcame the abscission retarding effect of IAA. The phenylurethane, Barban, blocked the GA acceleration of abscission, but it did not affect the rate of abscission of control or IAA treated midribs.

Journal Article↗
PubMed1984

Crown gall oncogenesis: evidence that a T-DNA gene from the Agrobacterium Ti plasmid pTiA6 encodes an enzyme that catalyzes synthesis of indoleacetic acid.

Stable incorporation of tumor-inducing (Ti) plasmid sequences, the T-DNA, into the genomes of dicotyledonous plants results in the formation of crown gall tumors. Previous genetic studies have suggested that the products of the genes encoding transcripts 1 and 2, which are encoded by the TL-DNA region of pTiA6, are responsible for inducing the auxin-independent phenotype of crown gall tissues. Here we report the construction of a plasmid, pMTlacT2, which directs the synthesis of the Mr 49,800 polypeptide encoded by the transcript 2 gene. Cell-free extracts prepared from Escherichia coli harboring this plasmid converted indoleacetamide to indoleacetic acid, the natural auxin of plants; extracts prepared from plasmidless strains of E. coli or strains harboring the cloning vehicle pBR322 did not carry out this reaction. We conclude that the transcript 2 gene of pTiA6 codes for an enzyme that participates in auxin biosynthesis, probably an indoleacetamide hydrolase.

DNA Restriction Enzymes↗
PubMed1976

Failure of Ethylene to Change the Distribution of Indoleacetic Acid in the Petiole of Coleus blumei X frederici during Epinasty.

The effect of ethylene on the distribution of applied indoleacetic acid in the petiole of Coleus blumei Benth. X C. frederici G. Taylor has been investigated during the development of epinastic curvature. Using intact plants, (14)C-IAA was applied to the distal region of the leaf lamina and the accumulation of label in the abaxial and adaxial halves of 5 mm petiole sections was determined after 1.5, 3, and 6 hours. Over this period the label was transported out of the lamina into the petiole at a rate of at least 66 mm hr(-1). Of the total amount of label in the petiole sections, 24 to 30% was located in the adaxial half and this distribution was not altered significantly by exposing plants to an atmosphere containing 50 mul/l ethylene. Thus when epinastic curvature is induced by ethylene there is no associated increase in the IAA content of the expanding adaxial half. The role of endogenous IAA in petiole epinasty was studied by restricting its movement with DPX 1840 (3,3a-dihydro-2-[p-methoxyphenyl]-8H-pyrozolo{5,1-a}isoindol-8-one). The leaf petioles still showed an initial epinastic response to ethylene. It is concluded that ethylene-induced epinasty is not dependent upon either any change in the transport of IAA or its redistribution within the petiole.

Journal Article↗
PubMed1982

Indoleacetic acid complementation and its relation to host range specifying genes on the Ti plasmid of Agrobacterium tumefaciens.

Host range variations were noted when 23 wild-type strains of Agrobacterium tumefaciens were tested on 27 different plant species. Because we have shown previously that host range specificity is conferred by the pTi plasmid, these variations in host specificity implicated genetic differences among pTi plasmids within the A. tumefaciens population that was tested. Host specificity was independent of the type of opine utilized and biotype of the strain used. These data suggested that separate genetic determinants operate for host specificity. This hypothesis was confirmed by Tn5 mutagenesis of the pTi plasmid, which generated mutants affected in host specificity. The regions of host specifying genes were located by displacement analysis of mutant pTi-plasmid-DNA restriction fragments. There are at least two sites on the pTiC58 plasmid: one within the T-region and the other about 75-77 kb to the right of this region. Mutations within the T-region were chemically complemented by indoleacetic acid, which restored the host range of the mutants. Such complementations were not observed with mutants outside the T-region.

Genes, Bacterial↗
PubMed1966

Hormonal Relations in the Phototropic Response: III. The Movement of C-labeled and Endogenous Indoleacetic Acid in Phototropically Stimulated Zea Coleoptiles.

The effect of phototropic stimulation of Zea coleoptile tips on the distribution of both endogenous indoleacetic acid (IAA) and applied C(14)-labeled IAA was determined. The tips rested on bisected agar blocks. More IAA was found in the blocks under the shaded side of the coleoptile tips than those under the irradiated side. However, no significant difference was observed between the total amounts of IAA, endogenous or labeled, in the irradiated and shaded sides of the experimental system. In addition, less endogenous auxin was found in the shaded tissues than in their irradiated counterparts. It is suggested that phototropism following unilateral irradiation with first positive radiant densities might be a consequence of lateral inequalities in the ability of the irradiated and shaded tissues to transport auxin basipetally.

Journal Article↗
PubMed1977

Temperature-dependent Response to Indoleacetic Acid Is Altered by NH(4) in Cultured Cotton Ovules.

Unfertilized cotton ovules, cultured in vitro, produced fiber in response to indoleacetic acid (IAA) and/or gibberellic acid (GA(3)). Of the two hormones, IAA produced the greater amount of fiber per ovule, and the effect of both hormones applied simultaneously was approximately additive. Depending upon in vitro culture temperature, a variable number of unfertilized cotton ovules produced fiber in response to 5 mum IAA. The response to IAA was "all or none" for each ovule. The percentage of ovules responding to 5 mum IAA ranged from zero at 28 C to 100 at 34 C. The ability to respond at nonpermissive culture temperatures (i.e. 28 to 30 C) was markedly increased by including 2.5 mm NH(4)NO(3) in the KNO(3)-based medium or by increasing concentrations of IAA. The inclusion of NH(4) (+) in the basal culture medium provided only an increased percentage of ovules producing fiber in the presence of IAA, but did not increase fiber production per ovule. Temperature, like GA(3), increased both the number of ovules producing fiber in response to IAA and the amount of fiber produced per ovule.

Journal Article↗
PubMed1966

Partial purification and kinetics of indoleacetic Acid oxidase from tobacco roots.

Extracts from roots of Nicotiana tabacum L var. Bottom Special contain oxidative enzymes capable of rapid degradation of indoleacetic acid (IAA) in the presence of Mn(2+) and 2, 4-dichlorophenol. Purification of IAA oxidase was attempted by means of ammonium sulfate fractionation and elution through a column of SE-Sephadex. Two distinct fractions, both causing rapid oxidation of IAA in the absence of H(2)O(2), were obtained. One fraction exhibited high peroxidase activity when guaiacol was used as the electron donor; the other did not oxidase guaiacol. Both enzyme fractions caused similar changes in the UV spectrum of IAA; absorption at 280 mmu was reduced, while major absorption peaks appeared at 254 and 247 mmu. The kinetics of IAA oxidation by both fractions were followed by measuring the increase in absorption at 247 mmu. The peroxidase-containing fraction showed no lag or a slight lag which could be eliminated by addition of H(2)O(2) (3 mumoles/ml). The peroxidase-free fraction showed a longer lag, but addition of similar amounts of H(2)O(2) inhibited the rate of IAA oxidation and did not remove the lag. With purified preparations, IAA oxidation was stimulated only at low concentrations of H(2)O(2) (0.03 mumole/ml). A comparison of K(m) values for IAA oxidation by the peroxidase-containing and peroxidase-free fractions suggests that tobacco roots contain an IAA oxidase which may have higher affinity for IAA and may be more specific than the general peroxidase system previously described from other plant sources. A similar oxidase is present in commercial preparations of horseradish peroxidase. It is suggested that oxidation of IAA by horseradish peroxidase may be due to a more specific component.

Journal Article↗
PubMed1993

Calcium Transport in Membrane Vesicles Isolated from Maize Coleoptiles (Effect of Indoleacetic Acid and Fusicoccin).

Maize (Zea mays L.) coleoptile segments loaded with 45Ca released about 50% of the ion after 1 h when treated with indoleacetic acid (IAA). In contrast, fusicoccin (FC) had no effect. The same relation was found when ATP-dependent Ca2+ transport, measured as 45Ca uptake, was determined in a plasmalemma-rich membrane vesicle fraction isolated from coleoptiles treated or untreated for 1 h with IAA or FC. In fact, IAA-treated membranes showed an increase in ATP-dependent 45Ca uptake by more than 30% with respect to the control and the FC treatment. Ca2+ uptake in IAA-treated membranes was only slightly affected (+27%) by supplying calmodulin (Cam) exogenously. However, Ca2+ uptake in membranes from the control and FC-treated coleoptiles were stimulated (+80%) by exogenous Cam. Calmidazolium, a Cam antagonist, inhibited Ca2+ uptake in the IAA treatment (-48%) to a greater extent with respect to the control and FC treatment (-33 and -29%, respectively). A possible relationship between the effect of IAA on the ATP-dependent Ca2+ transport activity, the involvement of Cam, and their effect on growth are discussed.

Journal Article↗
PubMed1985

Gravitropic Responses of Partially Decapitated Corn Coleoptiles with and without Applied [C]Indoleacetic Acid.

The curvature of corn seedling (Zea mays L. Mo17 x B73) coleoptiles which had been half-decapitated and supplied with [(14)C]indoleacetic acid (IAA) (3.2 micromolar, 51 milliCuries per millimole) was determined during a 3-hour period of gravitational stimulation. Curvature of such half-decapitated coleoptiles was found to be similar in rate and extent to that of intact coleoptiles responding to gravity. Gravitational stimulation was accomplished by reorienting seedlings to a horizontal position, either up or down with respect to the removed half of the coleoptile tips.The first set of experiments involved placing aluminum foil barriers along one of the two cut surfaces to restrict the movement of IAA into tissues. The initiation and extent of curvature of these half-decapitated coleoptiles was dependent upon the orientation of the removed half-tip and the accompanying barrier. The distribution of radioactivity from [(14)C] IAA after 3 hours indicated that the specific lateral movement of label was also dependent upon orientation of the removed half-tip of the coleoptile. A specific movement to the lower side of approximately 14% of the total recovered radioactivity was found in coleoptiles in which the [(14)C]IAA was supplied across a transverse cut surface. In contrast, specific movement of only 4% was found for application across a longitudinal cut surface.A second series of experiments was conducted using 1.0 and 3.2 micromolar [(14)C]IAA (51 milliCuries per millimole) supplied to half-decapitated coleoptiles without inserted barriers. The 3.2 micromolar concentration adequately replaced the removed coleoptile half-tips in terms of straight growth, but it did not result in as much curvature as shown by coleoptiles of intact seedlings. The 1 micromolar concentration was not adequate to replace the removed half-tip in straight growth, but resulted in gravitropic curvature nearly as great as that produced by the higher concentration.The data presented here suggest that strong auxin gradients are not produced in response to gravity stimulation based on the recovered radioactivity from [(14)C]IAA. However, it is evident that auxin is required for the development of normal gravitropic responses. It is possible, therefore, that an important early role of this movement is not to cause a large stimulation of growth on the lower side but to decrease growth on the upper side of a gravitropically responding coleoptile.

Journal Article↗
PubMed1967

Biosynthesis of Indoleacetic Acid from Tryptophan-C in Cell-free Extracts of Pea Shoot Tips.

A 2-step, 1-dimensional thin-layer chromatographic procedure for isolating indoleacetic acid (IAA) was developed and utilized in investigations of the biosynthesis of IAA from tryptophan-(14)C in cell-free extracts of pea (Pisum sativum L.) shoot tips. Identification of a (14)C-product as IAA was by (a) co-chromatography of authentic IAA and (14)C-product on thin-layer chromatography, and (b) gas-liquid and thin-layer chromatography of authentic and presumptive IAA methyl esters. Dialysis of enzyme extracts and addition of alpha-ketoglutaric acid and pyridoxal phosphate to reaction mixtures resulted in approximately 2- to 3-fold increases in net yields of IAA over yields in non-dialyzed reaction mixtures which did not contain additives essential to a transaminase reaction of tryptophan. Addition of thiamine pyrophosphate to reaction mixtures further enhanced net biosynthesis of IAA. It is concluded that the formation of indolepyruvic acid and its subsequent decarboxylation probably are sequential reactions in the major pathway of IAA biosynthesis from tryptophan in cell-free extracts of Pisum shoot tips. Comparison of maximum net IAA biosynthesis in extracts of shoot tips of etiolated and light-grown dwarf and tall pea seedlings revealed an order, on a unit protein N basis, of: light-grown tall > light-grown dwarf > etiolated tall congruent with etiolated dwarf. It is concluded that the different rates of stem elongation among etiolated and light-grown dwarf and tall pea seedlings are correlated, in general, with differences in net IAA biosynthesis and sensitivity of the tissues to IAA.

Journal Article↗
PubMed1989

Preparation and Properties of Antibodies against Indoleacetic Acid (IAA)-C5-BSA, a Novel Ring-Coupled IAA Antigen, as Compared to Two Other Types of IAA-Specific Antibodies.

Two types of indoleacetic acid (IAA) antigens have been described in the literature which show marked differences with respect to antibody specificity. In this communication an alternative antigen design is described. In the so-called IAA-C5-BSA conjugate, both the acetic acid group and the pyrrole moiety are presented free, as the covalent linkage between IAA and the carrier molecule is introduced in the benzene moiety. Antibodies were elicited in rabbits against this novel antigen. Using cross-reactivity data and the strategy of successive approximation for the measurements of auxin levels in the internodes of light-grown broad bean (Vicia faba L. cv Superfine), the three types of antibodies are compared.

Journal Article↗