False-positive urinary test for 5-hydroxyindoleacetic acid due to methocarbamol and mephenesin carbamate.
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Carbamates↗
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Early auxin-regulated polyadenylylated mRNA sequences in pea stem tissue.
Polyadenylylated mRNA from etiolated pea stem segments treated with or without 20 muM indoleacetic acid (IAA) for various periods of time was assayed by translating it in a wheat germ extract containing [(35)S]methionine and separating the translation products by two-dimensional gel electrophoresis. Within 2 hr IAA causes at least five mRNA sequences to increase in translational activity, relative to initial levels and to simultaneous controls; three of these rise significantly within 20 min after exposure of tissue to IAA but are apparently not elevated at 10 min, whereas the others begin to increase at successive times later than 30 min, and still others begin to change only later than 2 hr. These observations indicate an early, highly selective IAA regulation of mRNA amounts or activities, becoming progressively more extensive with time. The earliest detected enhancement seems close to the primary action of IAA but appears not to be rapid enough to be responsible for auxin induction of cell enlargement.
Journal Article↗
In vitro binding of gibberellin A(4) to extracts of cucumber measured by using DEAE-cellulose filters.
A rapid method for assaying [(3)H]gibberellin A(4) bound to a soluble protein from cucumber hypocotyls by using DEAE-cellulose filter discs is described. The binding is saturable, reversible with unlabeled gibberellin A(4), and has a half-life of association under nonequilibrium conditions at 0-4 degrees C of 6-7 min. By using this assay, the dissociation constant (K(d)) was estimated to be 70 nM and the number of binding sites, 0.4 pmol mg(-1) of soluble protein or 0.69 pmol g(-1) (fresh weight) of hypocotyls. The speed and reliability of the assay make it invaluable for kinetic studies involving competitors. Thus, it has been possible to show that gibberellins that are biologically active in a cucumber bioassay compete for binding to the same protein and their calculated affinity constants bear a direct relationship to their known activities in the cucumber bioassay. Gibberellins that are inactive in this bioassay and other plant hormones, such as indoleacetic acid, abscisic acid, and kinetin, show a noncompetitive interaction.
Journal Article↗
Cytokinin/auxin balance in crown gall tumors is regulated by specific loci in the T-DNA.
Insertion of the transposon Tn5 into the T-region of the octopine Ti plasmid of Agrobacterium tumefaciens gives rise to crown gall tumors having altered morphology. Three loci within the T-DNA that control tumor morphology have been detected [Garfinkel, D. J., Simpson, R. B., Ream, L. W., White, F. F., Gordon, M. P. & Nester, E. W. (1981) Cell 27, 143-153]. They influence tumor size (tml), production of roots (tmr), or production of shoots (tms). Cytokinin and auxin levels in such mutant tumors were examined by HPLC/radioimmunoassay and HPLC/fluorescence assay, respectively. Free indoleacetic acid levels (in pmol/g) were: uninfected tobacco stem tissues, 128; wild-type A348 tumors, 295; tml mutant tumors, 307; tmr mutant tumors, 129; and tms mutant tumors, 70. Average trans-ribosylzeatin levels were correspondingly: 0.97, 48, 40, 0.54, and 1,400 pmol/g. trans-Ribosylzeatin/indoleacetic acid ratios were as high as 24 in shoot-producing tumors and as low as 0.003 in root-producing tumors. The evidence strongly suggests that tumor phytohormone levels are determined by genes in the T-DNA.
Journal Article↗
Two genes encoding 1-aminocyclopropane-1-carboxylate synthase in zucchini (Cucurbita pepo) are clustered and similar but differentially regulated.
A 17-kilobase (kb) region of the zucchini (Cucurbita pepo) genome has been sequenced and contains two genes, CP-ACC1A and CP-ACC1B, encoding 1-aminocyclopropane-1-carboxylate synthase (ACC synthase; S-adenosyl-L-methionine methylthioadenosine-lyase, EC 4.4.1.14). The genes are transcribed convergently and are separated by a 5.7-kb intergenic region. Their coding regions are interrupted by four introns located in identical positions. While the DNA identity in their coding regions is 97%, their 5' and 3' flanking regions are highly divergent. Transcription of CP-ACCIA is rapidly induced by wounding in fruit and etiolated hypocotyls and by indoleacetic acid (IAA)/benzyladenine/LiCl only in fruit tissue. Conditions that induce CP-ACC1B expression have not been found. Protein synthesis inhibition derepresses the expression of CP-ACC1A and other unidentified ACC synthase genes, suggesting that they may be under negative control. The amino acid sequences deduced from the nucleotide sequences of the genes are 493 and 494 residues long with 95% identity. The most notable feature of the amino acid sequence is the presence of 11 of the 12 invariant amino acid residues involved in the binding of the substrate and pyridoxal-5'-phosphate in various aminotransferases. We conclude that ACC synthase is encoded by a multigene family of which certain members are differentially induced by auxin in a tissue-specific manner. Furthermore, ACC synthase, a pyridoxal-containing enzyme, may have an evolutionary relationship with the superfamily of aminotransferases.
Amino Acid Sequence↗
Changes in cytosolic pH and calcium of guard cells precede stomatal movements.
Stomatal opening is induced by indoleacetic acid (IAA), cytokinins, and fusicoccin (FC), whereas stomatal closure is induced by abscisic acid (ABA). To test the effect of these growth regulators on guard cell cytosolic Ca2+ ([Ca2+]cyt) and pH (pHcyt), epidermal strips were taken from the lower side of leaves of the orchid Paphiopedilum tonsum and were loaded with acetomethoxy-esterified forms of the Ca2+ indicator fluo-3 or the pH indicator 2',7'-bis(2-carboxyethyl)-5(6)carboxyfluorescein. Basal [Ca2+]cyt ranged from 0.05 to 0.3 M and was 0.22 +/- 0.015 (n = 21). Increases in both [Ca2+]cyt and pHcyt were observed in guard cells after application of 10-100 M ABA to open stomata, and these preceded stomatal closure. The increase in [Ca2+]cyt ranged from 1.5- to 3-fold and was seen in 7 of 10 experiments. Guard cell alkalinization began within 2 min of ABA treatment and continued for the next 8 min. The increase ranged from 0.04 to 0.3 pH unit and was seen in 13 of 14 experiments. Guard cell [Ca2+]cyt increased, whereas pHcyt decreased after treatment of closed stomata with IAA, kinetin, or FC. In response to 50-100 M IAA, [Ca2+]cyt increased 1.5- to 2-fold in all cases, and pHcyt decreased 0.2-0.4 unit within 5 min in 7 experiments. Within 12 min, 10-100 M kinetin caused [Ca2+]cyt to increase in 28 of 34 experiments (1.3- to 2.5-fold) and pHcyt fell 0.1-0.4 unit in 15 of 17 treatments. The response to 10-50 M FC was similar in both time and magnitude. These results show that stomatal opening is accompanied by an increase in [Ca2+]cyt and cytosolic acidification in the guard cells, whereas stomatal closure is preceded by an increase in [Ca2+]cyt and cytosolic alkalinization in the guard cells. The order of these events is still uncertain, but changes in pHcyt are correlated with stomatal movement, and these changes may be an important factor in the regulation of guard cell movement.
Journal Article↗
Cytokinin stimulates dihydropyridine-sensitive calcium uptake in moss protoplasts.
Ca2+ influx through dihydropyridine (DHP)-sensitive Ca2+ channels is thought to be an early event in cytokinin-induced bud formation in moss protonema because DHP antagonists inhibit bud formation in the presence of cytokinin and DHP agonists stimulate bud formation in the absence of cytokinin [Conrad, P. A. & Helper, P. K. (1988) Plant Physiol. 86, 684-687]. In the present study, we established the presence of a DHP-sensitive Ca2+ transport system by measuring 45Ca2+ influx into moss protoplasts. Ca2+ influx was stimulated by external KCl (up to 5 mM), indicating that transport is voltage-dependent. K(+)-induced Ca2+ influx was DHP-sensitive with > 50% inhibition at 500 nM nifedipine. Ca2+ influx was stimulated by increasing concentrations of the DHP Ca2+ channel agonist Bay K8644 with half-maximal effects at 25 nM; this stimulation was seen only in the absence of K+, suggesting that the agonist works preferentially on polarized membranes. Ca2+ influx was also inhibited by phenylalkylamines (verapamil) and benzothiazepines (diltiazem). The phytohormone 6-benzylaminopurine consistently stimulated Ca2+ influx with a Km value of 1 nM, whereas adenine, indoleacetic acid, and gibberellic acid had no effect on Ca2+ transport. The cytokinins kinetin and trans-zeatin caused a greater stimulation of Ca2+ influx and induced more bud formation than did 6-benzylaminopurine. These results indicate that Ca2+ is taken up into moss protoplasts through voltage-dependent DHP-sensitive Ca2+ channels on the plasma membrane and that one of the cytokinin effects in the induction of bud formation is regulation of this plasma membrane Ca2+ channel.
3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
Phenotypic and genotypic characterization of antagonistic bacteria associated with roots of transgenic and non-transgenic potato plants.
Rhizobacteria obtained during a risk assessment study from parental and transgenic T4 lysozyme-expressing potato plants were investigated to determine whether or not the strains could be grouped based on the source of isolation, transgenic or non-transgenic plants, respectively. A total of 68 representative bacterial strains of the group of enterics and pseudomonads were investigated by phenotypic profiling (the antagonistic activity towards bacterial and fungal plant pathogens, the production of the plant growth hormone indole-3-acetic acid [auxin], and the sensitivity to T4 lysozyme in vitro) and genotypic profiling by PCR fingerprints using BOX primers. All isolates were identified by fatty acid methyl ester (FAME) analysis. Computer-based analysis of the phenotypic characteristics showed that both, enterics and Pseudomonas strains clustered into six to seven groups at an Euclidian distance of 10. According to their BOX-PCR-generated fingerprints the Pseudomonas strains clustered into seven groups and the enterobacteria into two groups at the same genetic distance level of 10. The majority of groups were heterogeneous and contained isolates from all plant lines. In conclusion, cluster analysis of the phenotypic and genotypic features did not reveal correlations between bacterial isolates and transgenic character of plants.
Cluster Analysis↗
Insulin reverses ammonia-induced anorexia and experimental cancer anorexia.
Previous experiments suggest that experimental cancer-induced anorexia is associated with hyperammonemia and that daily injections of insulin may attenuate the anorexia for several days. In the present study, we determined whether similar daily insulin treatments would correct anorexia induced by the infusion of ammonium salts and compared this feeding response with that of insulin-treated tumor-bearing (TB) rats. Daily treatment of control and anorectic TB rats with systemically administered insulin for six days increased feeding in all control rats and 40% of the TB rats. All insulin-treated groups exhibited equal degrees of hypoglycemia irrespective of anorexia. Basal concentrations of lactate and glucagon were elevated in saline-treated TB rats. Plasma lactate levels were normalized by insulin treatment, whereas glucagon was normalized only in the TB rats that fed to insulin and increased further in TB rats that did not feed to insulin. Elevated hypothalamic tyrosine was reduced in insulin-treated TB rats that ate, and 5-hydroxy-indoleacetic acid was increased further when the rats did not eat. Insulin also blocked anorexia resulting from the intravenous infusion of ammonium salts. Hypothalamic concentrations of tyrosine and tryptophan were increased by the ammonia infusion and reduced significantly in insulin-treated infused rats. These results indicate that insulin treatment can reverse experimental cancer-induced anorexia and hyperammonemia-induced anorexia. Neurochemical changes associated with these treatments are also similar, but not identical.
Ammonia↗
Alterations in tryptophan metabolism in man after irradiation.
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Abdomen↗
Serotonin and melatonin synthesis in peripheral blood mononuclear cells: stimulation by interferon-gamma as part of an immunomodulatory pathway.
Serotonin and melatonin inhibit phytohemagglutinin- (PHA) induced interferon-gamma (IFN-gamma) production by lymphocytes. In this paper, it is shown that IFN-gamma-increased tryptophan uptake by lymphocytes and macrophages led to an enhanced production of serotonin. When IFN-gamma and serotonin were added together to a lymphocyte culture, N-acetyl serotonin and melatonin production was increased, whereas the path to 5-hydroxy-indoleacetic acid remained unchanged. Therefore, the stimulated IFN-gamma production of serotonin and melatonin by lymphocytes and macrophages and the inhibition of IFN-gamma synthesis by these indoleamines suggest a hypothesis for an immunoregulatory circuit.
Cells, Cultured↗
Clinical significance of blood chromogranin A measurement in neuroendocrine tumours.
BACKGROUND: Tumour marker measurement gives clinicians useful information for the follow-up and management of patients with neuroendocrine tumours (NETs). The currently used tumour markers for NETs are neuron-specific enolase (NSE) and chromogranin A (CgA). The clinical accuracy of these biomarkers depends on histotype and disease extent. CgA is thought to be the optimal marker for most NETs, as it is independent of the biological characteristics of the tumour. AIM OF THE STUDY: In this study we investigated the value of CgA assessment with respect to the other biomarkers in the diagnosis and follow-up of patients with different types of NETs. PATIENTS AIND METHODS: We measured CgA, NSE, carcinoembryonic antigen (CEA) and urine 5-hydroxy-3-indoleacetic acid (5-HIAA) in 290 patients with 127 gastroenteropancreatic (GEP) tumours, 49 neuroblastomas, 36 lung tumours, 24 medullary thyroid carcinomas (MTCs). 15 pNETs, 12 paragangliomas. 7 Merkel's cell carcinomas (MCCs) and 20 NETs of unknown origin. CgA and 5-HIAA were quantitated by immunoenzymatic assays, while NSE and CEA were determined by radioimmunoassays. RESULTS: The biomarkers' specificity in GEP tumours was 86% for CgA, 100% for NSE, 91% for CEA and 100% for 5-HIAA. The corresponding sensitivity was 68% for CgA, 33% for NSE, 15.4% for CEA and 35% for 5-HIAA. The sensitivity of CgA largely depends on disease extent or presence of functioning tumours and is highest in metastatic and syndromic patients. CgA determination in GEP tumour monitoring is useful to evaluate the response to therapy and to follow up patients with liver metastases. In neuroblastomas the overall specificity of NSE and CgA was 50%, and 83%, respectively. In these tumours NSE sensitivity was close to 90% in all clinical stages, while the sensitivity of CgA depended on clinical stage (50% for stage I and II, 60% for stage III and 100% for stage IV tumours). Also in this type of tumour changes in CgA levels correlated with objective response. In paragangliomas CgA measurement may provide useful clinical information. Measurement of CgA is of use in the diagnosis of lung carcinoids, while its value in MTCs, pNETs and MCCs is very limited. CONCLUSIONS: CgA was confirmed to be the best tumour marker currently available for identifying patients suffering from NETs of the GEP system, lung carcinoids and neuroblastomas. CgA evaluation is recommended in the follow-up of patients with such tumours.
Biomarkers, Tumor↗
Inhibition of the indole-3-acetic acid-induced epinastic curvature in tobacco leaf strips by 2,4-dichlorophenoxyacetic acid.
It has been reported that auxin induces an epinastic growth response in plant leaf tissues. Leaf strips of tobacco (Nicotiana tabacum L. 'Bright Yellow 2') were used to study the effects of indole-3-acetic acid (IAA), the principal form of auxin in higher plants, and a synthetic auxin, 2,4-dichlorophenoxyacetic acid (2,4-D), on epinastic leaf curvature. Incubation of leaf strips with 10 micro M IAA resulted in a marked epinastic curvature response. Unexpectedly, 2,4-D showed only a weak IAA-like activity in inducing epinasty. Interestingly, the presence of 2,4-D resulted in inhibition of the IAA-dependent epinastic curvature. In vivo Lineweaver-Burk kinetic analysis clearly indicated that the interaction between IAA and 2,4-D reported here is not a result of competitive inhibition. Using kinetic analysis, it was not possible to determine whether the mode of interaction between IAA and 2,4-D was non-competitive or uncompetitive. 2,4-D inhibits the IAA-dependent epinasty via complex and as yet unidentified mechanisms.
2,4-Dichlorophenoxyacetic Acid↗
Nitrogen regulation of root branching.
BACKGROUND: Many plant species can modify their root architecture to enable them to forage for heterogeneously distributed nutrients in the soil. The foraging response normally involves increased proliferation of lateral roots within nutrient-rich soil patches, but much remains to be understood about the signalling mechanisms that enable roots to sense variations in the external concentrations of different mineral nutrients and to modify their patterns of growth and development accordingly. SCOPE: In this review we consider different aspects of the way in which the nitrogen supply can modify root branching, focusing on Arabidopsis thaliana. Our current understanding of the mechanism of nitrate stimulation of lateral root growth and the role of the ANR1 gene are summarized. In addition, evidence supporting the possible role of auxin in regulating the systemic inhibition of early lateral root development by high rates of nitrate supply is presented. Finally, we examine recent evidence that an amino acid, L-glutamate, can act as an external signal to elicit complex changes in root growth and development. CONCLUSIONS: It is clear that plants have evolved sophisticated pathways for sensing and responding to changes in different components of the external nitrogen supply as well as their own internal nitrogen status. We speculate on the possibility that the effects elicited by external L-glutamate represent a novel form of foraging response that could potentially enhance a plant's ability to compete with its neighbours and micro-organisms for localized sources of organic nitrogen.
Arabidopsis↗
Biochemistry and schizophrenia III. A review of childhood psychosis.
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Autistic Disorder↗
Urinary acid metabolites of biogenic amines in schizophrenic patients.
A hypothesis is presented that only pure type B monoamine oxidase (MAO) amine substrates and their oxidized metabolites should be altered in mental patients, especially paranoid chronic schizophrenics. If urinary pH is rigorously controlled, it is predicted that 24-hour urinary amine levels (free and total) of pure type B MAO substrates will be elevated and their corresponding acid metabolites reduced, especially under excess substrate conditions in vivo. The usual 50 percent decrease in platelet MAO, which is reported to be in some schizophrenic patients in vitro, should especially show biochemical functional deficits in vivo when the organism is stressed with a suitable amine or amino acid substrate given as a diagnostic load. Such an approach amy be useful in demonstrating a functional biochemical deficit and the biological significance of low platelet MAO activity (a type B MAO) seen in some psychiatric patients.
Biogenic Amines↗
In vitro shoot proliferation determined by explant orientation of juvenile and mature Quercus rubra L.
Shoot cultures of Quercus rubra (L.) were established from both juvenile and adult plant material. Initial explants from epicormic shoots formed on the basal zone of the trunks had a greater capacity for in vitro establishment than explants from crown branches. The growth of vigorous axillary shoots was obtained by culturing decapitated shoots horizontally on Woody Plant Medium supplemented with 0.2 mg l(-1) of 6-benzylaminopurine. After 3 weeks of culture the shoots were transferred to fresh medium for two more weeks, giving a 5-week multiplication cycle. Efficient shoot production was achieved by combining three treatments favoring the growth of lateral buds: excision of the apex, horizontal culture and cytokinin treatment. The addition of indoleacetic acid or indolebutyric acid to the multiplication medium did not improve shoot proliferation rates, and naphthaleneacetic acid was detrimental. Recycling the same explant for several successive subcultures improved the efficiency of the propagation procedure. Using the optimal multiplication procedures, nine clones (six of juvenile origin and three from adult trees) were tested in vitro and it was found that genotype and age affected performance.
Journal Article↗
Role of T-region borders in Agrobacterium host range.
The limited host range AB3 strain of Agrobacterium tumefaciens induces tumors by transferring two T-regions, TA and TB. TA is a deleted version of the well-known biotype I octopine TL-region that lacks the iaa and ipt genes, but carries an intact oncogene, gene 6b, and typical left and right border sequences. TB carries two iaa genes that together code for the synthesis of indoleacetic acid. Gene 6b and the iaa gene act synergistically when transferred in a coinoculation experiment. The TA-region of the limited host range isolate Ag57 is related to the TA-region of AB3, but differs from it at several positions. The most significant difference is the absence of the right border region. In spite of this, Ag57 and the exconjugant strain C58C9(pTiAg57) induce normal tumors on Nicotiana rustica and Vitis vinifera. Various experiments indicate that gene 6b of the Ag57 TA-region is active and transferred in spite of the absence of the right border. On N. tabacum, C58C9(pTiAg57) is nononcogenic but becomes oncogenic when the pTiAg57 TA-region is restored by the right TA border sequence of pTiAB3. Thus, the right TA border sequence of the biotype III limited host range strains is required for tumor induction on some hosts, but not on others.
Agrobacterium tumefaciens↗