15 results on '"Werner J. Meudt"'
Search Results
2. Indole-3-acetic Acid (IAA) and IAA Conjugates Applied to Bean Stem Sections
- Author
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Krystyna Bialek, Jerry D. Cohen, and Werner J. Meudt
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chemistry.chemical_classification ,Chromatography ,biology ,Physiology ,food and beverages ,High resolution ,Articles ,Plant Science ,Isotope dilution ,biology.organism_classification ,Hydrolysis ,chemistry.chemical_compound ,chemistry ,Biochemistry ,Auxin ,Genetics ,heterocyclic compounds ,Phaseolus ,Indole-3-acetic acid ,Conjugate ,Maximum rate - Abstract
High resolution growth recording techniques and reverse isotope dilution analysis were used to study the relationship between indole-3-acetic acid (IAA) concentration and curvature of excised bean (Phaseolus vulgaris L. cv Bush Burpee Stringless) first internode sections unilaterally treated with hormone. The maximum rate of curvature occurred rapidly (within 25 minutes) and was proportional to the log of the amount of applied IAA recovered in the tissue. The rate of curvature decreased after 30 minutes although little or no lateral migration of applied IAA occurred and tissue levels of IAA increased. The biologic activity of IAA-amino acid conjugates was found to be directly related to the amount of free IAA, resulting from their hydrolysis, which could be recovered from the tissue.
- Published
- 1983
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3. Rapid Bioassay for Auxin
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Werner J. Meudt and Howard W. Bennett
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Indole test ,chemistry.chemical_classification ,food.ingredient ,Filter paper ,Physiology ,food and beverages ,Cell Biology ,Plant Science ,General Medicine ,Biology ,biology.organism_classification ,chemistry.chemical_compound ,Avena ,food ,chemistry ,Biochemistry ,Auxin ,Etiolation ,Genetics ,Biophysics ,Bioassay ,Phaseolus ,Gibberellic acid - Abstract
A rapid bioassay is described for the detection of growth substances. The bioassay is simple to perform under ordinary laboratory or classroom conditions and the sensitivity to auxin is comparable to other bioassays, including those using Avena first internode sections. The bioassay is performed on isolated first internode sections from partly etiolated bean plants (Phaseolus vulgaris L. cv. Bush Burpee Stringless Bush Bean). The test material is applied to one side and near the base of the section. Auxin treatments induce curvature and the distance of the lateral displacement of the apical portion of the segment is proportional to the concentration applied. Routinely, the indole 3-acetic acid response is measured 1 to 3 h after treatment. The sections also respond to gibberellic acid (GA3), which induces an increase in overall length, but unlike auxin, GA3 does not cause curvature. The test compounds are applied via a small filter paper disk that provides a convenient means for studying interactions of two or more compounds by co-applications. Auxin-induced growth can be monitored with a sensitive motion detector. Data are presented which confirm the usefulness of the assay.
- Published
- 1978
- Full Text
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4. Interactions of sulfite and manganous ion with peroxidase oxidation products of indole-3-acetic acid
- Author
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Werner J. Meudt
- Subjects
biology ,Radical ,Inorganic chemistry ,Hyperchromicity ,food and beverages ,Plant Science ,General Medicine ,Horticulture ,Photochemistry ,Biochemistry ,Redox ,chemistry.chemical_compound ,Electron transfer ,chemistry ,Sulfite ,biology.protein ,Hypsochromic shift ,Indole-3-acetic acid ,Molecular Biology ,Peroxidase - Abstract
Chemical and spectral data were used to study the fate of IAA during the first minute of its peroxidase catalysed oxidation. In the first 30 sec of the reaction, a hypsochromic shift of 2 nm was detected in the UV spectrum of IAA. In the presence of sulfite, the rate of spectral shift is enhanced. As the oxidation of IAA proceeds, the effect of sulfite diminishes, being ineffective when added to the reaction after 20–30 sec. The loss of the sulfite effect coincides with a hyperchromic shift at 264 nm. This is not observed when sulfite is added at the beginning of the oxidation reaction. The rate of the hypochromic shift at 282 nm is greatly enhanced when sulfite is added at the start of the reaction, but is ineffective when added after 30–40 sec. The initial effect of sulfite is attributed to a chain reaction of unstable IAA-free radicals and sulfite oxidation, and this is further enhanced by manganous ions, which function in electron transfer between sulfite ions and IAA-free radicals.
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- 1971
- Full Text
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5. Studies on the Oxidation of Indole-3-Acetic Acid by Peroxidase Enzymes. I. Colorimetric Determination of Indole-3-Acetic Acid Oxidation Products
- Author
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Werner J. Meudt and T. Powell Gaines
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chemistry.chemical_classification ,biology ,Physiology ,food and beverages ,Articles ,Plant Science ,Tautomer ,Redox ,chemistry.chemical_compound ,Enzyme ,chemistry ,Reagent ,Yield (chemistry) ,Genetics ,biology.protein ,Organic chemistry ,heterocyclic compounds ,Indole-3-acetic acid ,Peroxidase - Abstract
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 Ehrlich9s 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 Ehrlich9s reagents. Data discussed support a concept that the color produced with DMACA is due to the presence of tautomeric oxidation product(s) of IAA.
- Published
- 1967
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6. Indole-3-acetic Acid Oxidase in a Nicotiana Hybrid and its Parental Types
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Werner J. Meudt
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Oxidase test ,Physiology ,fungi ,food and beverages ,Cell Biology ,Plant Science ,General Medicine ,Metabolism ,Biology ,biology.organism_classification ,chemistry.chemical_compound ,Transformation (genetics) ,chemistry ,Botany ,Genetics ,heterocyclic compounds ,Topographical distribution ,Indole-3-acetic acid ,Function (biology) ,Nicotiana ,Hybrid - Abstract
The metabolism of IAA is correlated with tumor formation in the Nicotiana hybrid, N. glauca x langsdorffii. Higher IAA-oxidase activity was found in leaves of hybrid plants than in leaves of parental types. Furthermore, topographical distribution study revealed that young expanding leaves contained more IAA-oxidase activity than older leaves. In hybrid plants, there is a close correlation between IAA-oxidase activity and the ability of a leaf to produce tumors. Leaves which yield the greatest number of injury-induced tumors also yield the highest IAA-oxidase activity. IAA incites callus-like outgrowths in hybrid plants which do not differentiate into a multitude of apices as is the case with spontaneous tumors. The results are interpreted on the basis of a concept that the IAA-oxidase system in plants may function as part of an IAA activating mechanism rather than in the basis of an IAA destroying system.
- Published
- 1970
- Full Text
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7. STUDIES ON THE OXIDATION OF INDOLE-3-ACETIC ACID BY PEROXIDASE ENZYMES
- Author
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Werner J. Meudt
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Electrophoresis ,Indole test ,chemistry.chemical_classification ,Indoleacetic Acids ,biology ,Cytochrome c peroxidase ,General Neuroscience ,General Biochemistry, Genetics and Molecular Biology ,Plants, Toxic ,chemistry.chemical_compound ,Enzyme ,Peroxidases ,History and Philosophy of Science ,chemistry ,Biochemistry ,Spectrophotometry ,Tobacco ,biology.protein ,Indole-3-acetic acid ,Oxidation-Reduction ,Peroxidase - Published
- 1967
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8. DPX 1840-induced Organogenesis in Xanthi-nc Tobacco Plants
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Werner J. Meudt and Howard W. Bennett
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Physiology ,Callus formation ,Nicotiana tabacum ,fungi ,food and beverages ,Organogenesis ,Plant Science ,Articles ,Biology ,Meristem ,biology.organism_classification ,Abscission ,Anthesis ,Callus ,Shoot ,Botany ,Genetics - Abstract
The synthetic growth regulant DPX 1840 (3,3a-dihydro-2-(p-methoxyphenyl)-8H-pyrazolo[5, 1-a]isoindol-8-one) induced callus growth and subsequent tissue differentiation on cut surfaces of decapitated Xanthi-nc tobacco plants (Nicotiana tabacum). Callus formation and organogenesis induced by DPX 1840 depended on the presence of leaves. The adventitious meristems developed into either vegetative or flowering shoots. Pedicels that bore single flower buds developed two abscission zones that caused the buds to abscise before anthesis. The various morphological and physiological processes affected by DPX 1840 suggests that this growth regulator affects the endogenous hormonal distribution and/or activity.
- Published
- 1975
9. Investigations on the Mechanism of the Brassinosteroid Response: I. Indole-3-acetic Acid Metabolism and Transport
- Author
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Werner J. Meudt and Jerry D. Cohen
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chemistry.chemical_classification ,Block method ,biology ,Physiology ,Cell ,food and beverages ,Plant Science ,Metabolism ,Articles ,Isotope dilution ,biology.organism_classification ,chemistry.chemical_compound ,medicine.anatomical_structure ,chemistry ,Biochemistry ,Auxin ,Genetics ,medicine ,Brassinosteroid ,heterocyclic compounds ,Phaseolus - Abstract
A brassinosteroid treatment of light-grown first internode sections of Phaseolus vulgaris results in an increased bending response following unilateral indole-3-acetic acid (IAA) application. Reverse isotope dilution analysis shows that this increased response is not due to an increase in the concentration of applied IAA in the tissue or a change in the amount of IAA conjugated. Treatment with the brassinosteroid also does not affect the rate of IAA transport as measured using the agar block method. These results indicate that even though brassinosteroid potentiates auxin action, it does not have a direct effect on IAA uptake, metabolism, or cell to cell transport.
- Published
- 1983
10. Investigations on the Mechanism of the Brassinosteroid Response: VI. Effect of Brassinolide on Gravitropism of Bean Hypocotyls
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Werner J. Meudt
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chemistry.chemical_classification ,Physiology ,Growth factor ,medicine.medical_treatment ,Gravitropism ,fungi ,food and beverages ,Plant Science ,Biology ,biology.organism_classification ,Hypocotyl ,chemistry.chemical_compound ,chemistry ,Auxin ,Development and Growth Regulation ,Botany ,Genetics ,medicine ,Biophysics ,Brassinosteroid ,Phaseolus ,Plant stem ,Brassinolide - Abstract
Brassinosteroids are steroidal lactones of plant origin that promote growth of a number of plant systems, and particularly the growth induced by auxins. Biologically active brassinosteroids (BR) also promote the growth of gravisensitive hypocotyls of 7-day-old light grown Phaseolus vulgaris when gravistimulated. Brassinolide-mediated promotion of curvature of gravistimulated internodes occurs in the absence of exogenously supplied indole-3-acetic acid (IAA). This is in contrast to the BR-promoted bending of vertically positioned bean hypocotyls, which is dependent upon exogenous IAA. Brassinosteroid treatment increased the graviperception of young internode tissues and the bending of the gravistimulated sections as well as the subsequent reversal of bending after the sections were placed vertically. These results indicate that BR sensitizes bean hypocotyls to gravistimulation and potentiates the action of a growth factor that induces gravitropic growth.
- Published
- 1987
11. Chemical and Biological Aspects of Brassinolide
- Author
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Werner J. Meudt
- Published
- 1987
- Full Text
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12. Synthesis of brassinosteroids and relationship of structure to plant growth-promoting effects
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Samson R. Dutky, David W. Spaulding, Malcolm J. Thompson, N. Bhushan Mandava, W. R. Lusby, and Werner J. Meudt
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Double bond ,Stereochemistry ,medicine.medical_treatment ,Clinical Biochemistry ,Substituent ,Plant Development ,Ring (chemistry) ,Biochemistry ,Steroid ,chemistry.chemical_compound ,Structure-Activity Relationship ,Endocrinology ,Steroids, Heterocyclic ,Plant Growth Regulators ,medicine ,Side chain ,Structure–activity relationship ,Molecular Biology ,Alkyl ,Brassinolide ,Pharmacology ,chemistry.chemical_classification ,Organic Chemistry ,Plants ,chemistry ,Biological Assay - Abstract
A number of brassinosteroids with and without hydroxyl groups or an alkyl substituent in their side chain were synthesized. The alkyl substituent at C-24 highly influenced the oxidation of the C-22 double bond with osmium tetroxide and, hence the ratio of the 22 beta,23 beta- and 22 alpha,23 alpha-glycolic isomers obtained. Two different bean bioassays used to compare the plant growth-promoting capabilities of these compounds and of brassinolide and its three side chain 22,23-cis-glycolic isomers showed that brassinolide was the most active. The next most active brassinosteroids were generally those with 22 alpha-OH, 23 alpha-OH orientation and a beta-methyl or alpha-ethyl substituent at C-24. Similarly, of the synthetic precursor tetrahydroxy ketones of the brassinosteroids, those with 22 alpha-OH, 23 alpha-OH orientation (like brassinolide) and an alkyl group at C-24 were also the most active in both bioassays. The results indicate stringent structural features are required for a steroid to induce brassin activity. The structural requirements are: a trans A/B ring system (5alpha-hydrogen), a 6-ketone or a 7-oxa-6-ketone system in ring B, cis alpha-oriented hydroxyl groups at C-2 and C-3, cis hydroxy groups at C-22 and C-23 as well as a methyl or ethyl substituent at C-24.
- Published
- 1982
13. Promotion of Peroxidase Activity in the Cell Wall of Nicotiana
- Author
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Kathleen J. Stecher and Werner J. Meudt
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chemistry.chemical_classification ,Oxidase test ,biology ,Physiology ,Plant Science ,Articles ,biology.organism_classification ,Cell wall ,Electrophoresis ,chemistry ,Biochemistry ,Auxin ,Cytoplasm ,Genetics ,biology.protein ,Polyacrylamide gel electrophoresis ,Peroxidase ,Nicotiana - Abstract
Peroxidase catalyzes the oxidation of indole-3-acetic acid. The primary products of this reaction stimulate growth in plants. Therefore, our concept is that an increase in peroxidase activity will increase the effect of indole-3-acetic acid as a growth hormone. Our objective was to study the effect of 2,3,5-triiodobenzoic acid, a growth regulator, on isoperoxidases in the cell wall and cytoplasm of Nicotiana. Isoperoxidases from the cell wall and cytoplasmic fractions were separated by acrylamide gel electrophoresis. We found that 2,3,5-triiodobenzoic acid and indole-3-acetic acid increase peroxidase activity in the cell wall. Since both 2,3,5-triiodobenzoic acid and indole-3-acetic acid increase the activity of the same isoperoxidase, we conclude that 2,3,5-triiodobenzoic acid synergizes rather than antagonizes auxin action, and we suggest that this increase in indole-3-acetic acid oxidase activity sensitizes plant tissues to auxin.
- Published
- 1972
14. Electrophoretic Isolation and Growth Activity of Indole-3-Acetic Acid Oxidation Products
- Author
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Werner J. Meudt
- Subjects
chemistry.chemical_classification ,biology ,food and beverages ,RNA ,Biological activity ,Oxidative phosphorylation ,chemistry.chemical_compound ,Transformation (genetics) ,Enzyme ,chemistry ,Biochemistry ,Auxin ,biology.protein ,heterocyclic compounds ,Indole-3-acetic acid ,Peroxidase - Abstract
Indole-3-acetic acid (IAA) is oxidized by peroxidase enzymes. The physiological significance ascribed to this reaction is that it controls or regulates the biological activity of IAA. There are two views as to the function of auxin oxidases, one degradative and the other an activation role. The prevailing concept is that the oxidation of IAA represents a detoxification reaction considered necessary for plant to keep the level of IAA at an optimum for maximal physiological response (Galston and Davies 1969). Contrary to the concept of inactivation of IAA, it is proposed that the oxidative transformation of IAA also activates IAA (Meudt, 1965 and 1967). Furthermore, the function of an IAA oxidase, in a system other than for the inactivation of IAA, is suggested by our findings that binding of IAA, first shown by Siegel and Galston (1953), depends on prior oxidation of IAA (Meudt and Galston, 1962). It was suggested that the binding of IAA depended on at least two reactions; (1) enzymatic transformation of IAA by the IAA oxidase system followed by; (2) the binding of a primary oxidation product to RNA, (Galston, et al 1964). In 1967, Meudt and Gaines proposed that the binding involved an indolenine derivative conjectured to be an early oxidation product of IAA (Ray and Thimann, 1955 and Hinman and Lang, 1965). The IAA oxidase system thus assumes a new significance. The present paper collates data on the isolation, electrophoretic mobility, and biological activity of 3 oxidation products of IAA.
- Published
- 1972
- Full Text
- View/download PDF
15. Ecology and Metabolism of Plant Lipids
- Author
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GLENN FULLER, W. DAVID NES, J. B. Mudd, D. G. Bishop, J. Sanchez, K. F. Kleppinger-Sparace, S. A. Sparace, J. Andrews, S. Thomas, C. R. Spray, B. O. Phinney, P. K. Stumpf, Werner J. Meudt, Mark A. Johnson, Rodney Croteau, Stella D. Elakovich, Thomas J. Bach, Hartmut K. Lichtenthaler, Edward J. Parish, Susan Bradford, Victoria J. Geisler, Patrick K. Hanners, Rick C. Heupel, Phu H. Le, P. E. Kolattukudy, Mark S. Crawford, Charles P. Woloshuk, William F. Ettinger, Charles L. Soliday, James A. Svoboda, Malcolm J. Thompson, Ruben Lozano, Mark F. Feldlaufer, Gunter F. Weirich, David J. Chitwood, William R. Lusby, Jon J. Kabara, Karl Poralla, Elmar Kannenberg, William R. Nes, John D. Weete, James G. Roddick, James L. Kerwin, Robert A. Moreau, Ronald L. Cihlar, Kathryn A. Hoberg, GLENN FULLER, W. DAVID NES, J. B. Mudd, D. G. Bishop, J. Sanchez, K. F. Kleppinger-Sparace, S. A. Sparace, J. Andrews, S. Thomas, C. R. Spray, B. O. Phinney, P. K. Stumpf, Werner J. Meudt, Mark A. Johnson, Rodney Croteau, Stella D. Elakovich, Thomas J. Bach, Hartmut K. Lichtenthaler, Edward J. Parish, Susan Bradford, Victoria J. Geisler, Patrick K. Hanners, Rick C. Heupel, Phu H. Le, P. E. Kolattukudy, Mark S. Crawford, Charles P. Woloshuk, William F. Ettinger, Charles L. Soliday, James A. Svoboda, Malcolm J. Thompson, Ruben Lozano, Mark F. Feldlaufer, Gunter F. Weirich, David J. Chitwood, William R. Lusby, Jon J. Kabara, Karl Poralla, Elmar Kannenberg, William R. Nes, John D. Weete, James G. Roddick, James L. Kerwin, Robert A. Moreau, Ronald L. Cihlar, and Kathryn A. Hoberg
- Subjects
- Plant lipids--Congresses, Plant lipids--Metabolism--Congresses, Plant ecology--Congresses
- Published
- 1987
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