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1.
Plant Physiol ; 77(3): 784-5, 1985 Mar.
Article in English | MEDLINE | ID: mdl-16664134

ABSTRACT

Indole-3-acetylaspartate and indole-3-acetylglutamate were isolated from 1-week-old, green cucumber shoots that had not been pretreated with auxin. Using isotope dilution techniques, we found 129 micrograms (0.42 micromoles) of indoleacetylglutamate and 33 micrograms (0.11 micromoles) of indoleacetylaspartate per kilogram of fresh tissue.

2.
J Med Eng Technol ; 7(1): 27-8, 1983.
Article in English | MEDLINE | ID: mdl-6842567

ABSTRACT

A hydraulic seat-rise wheelchair constructed for a patient experiencing severe difficulty getting into and out of a wheelchair is described. The seat-rise mechanism, activated by a hydraulic cylinder, is constructed to locate within a wheelchair frame replacing the seat and back of a normal manual wheelchair. Patient control of the lifting and lowering feature is maintained by controls fitted to the arm of the wheelchair. A wheelchair of this design is most suitable for use by patients who, by virtue of their disability, require it to achieve greater independence.


Subject(s)
Wheelchairs , Equipment Design , Humans
3.
Plant Physiol ; 70(1): 283-6, 1982 Jul.
Article in English | MEDLINE | ID: mdl-16662461

ABSTRACT

Incubation of hypocotyl segments of light-grown Cucumis sativus L. in 0.1 millimolar 3-indoleacetic acid for 16 hours led to the formation of indoleacetylaspartate and indoleacetylglutamate. There was no evidence for the formation of other conjugates of 3-indoleacetic acid with individual amino acids during the period from 4 to 48 hours of incubation. Indoleacetylglutamate reached its maximum concentration after about 4 hours of incubation and indoleacetylaspartate after about 8 hours. These levels remained unchanged for at least 40 hours. Indoleacetylaspartate caused small increases in cucumber hypocotyl segment growth at high concentrations, 1 millimolar being more effective than 0.1 millimolar.

4.
J Biomed Eng ; 2(4): 285-9, 1980 Oct.
Article in English | MEDLINE | ID: mdl-7464081

ABSTRACT

The intersegmental loads transmitted by the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints of the index finger are presented in activities involving application of a twisting moment by the hand. Twenty normal subjects, ten males and ten females were included in the studies. A six component load transducer was incorporated in each of the two fixtures representing a water tap and a jar cap 70mm in diameter and the maximal loading on the fingers was monitered in applying an isometric twisting moment to these structures. Two different hand configurations were studied for each activity: the spatial position and orientation of the finger segments were determined using two orthogonally positioned still cameras, and specially designed stick markers were utilized to highlight anatomical landmarks. The results confirm the use of the finger in a complex three-dimensional manner with no significant differences between the male and female subjects. Forces recorded in the jar cap activity were larger than those applied in the tap activity, the maximum being around 100 N and in general the abduction/adduction moments developed at both joints were of comparable magnitude to flexion/extension. Torques as high as 0.6 Nm and 1.0 Nm were calculated at the PIP and MCP joints respectively.


Subject(s)
Finger Joint/physiology , Adult , Biomechanical Phenomena , Female , Humans , Male , Metacarpophalangeal Joint/physiology , Middle Aged
5.
Plant Physiol ; 65(1): 107-13, 1980 Jan.
Article in English | MEDLINE | ID: mdl-16661122

ABSTRACT

Indoleacetaldehyde reductase catalyzes the conversion of indoleacetaldehyde to indole ethanol in extracts of Cucumis sativus L., with reduced pyridine nucleotide required as co-substrate. NADH and NADPH result in markedly different enzyme behavior, as reflected in reaction kinetics and in responses to inhibitors and activators. It is not yet clear whether there are two separate enzymes, one specific for NADH and the other for NADPH, or whether there is a single enzyme differentially influenced by the two co-substrates.In the presence of NADH, the indoleacetaldehyde reductase activity was inhibited by NaCl and displayed hyperbolic kinetics under all conditions tested. However, in the presence of NADPH the enzyme was activated by NaCl at concentrations up to 0.1 molar. Under certain conditions with NADPH as co-substrate, the enzyme showed kinetics sigmoidal with respect to indoleacetaldehyde concentration and was strongly inhibited by high concentrations of NADPH. It is possible that this substrate inhibition of the NADPH-linked indoleacetaldehyde reductase activity by NADPH, as well as the sigmoidicity with respect to indoleacetaldehyde concentration, may function in the regulation of auxin biosynthesis.

6.
Plant Physiol ; 61(1): 104-6, 1978 Jan.
Article in English | MEDLINE | ID: mdl-16660219

ABSTRACT

The presence of indoleacetaldehyde in cucumber (Cucumis sativus L.) cotyledons was demonstrated by thin layer chromatographic R(F) values in three solvent systems, by the formation and hydrolysis of a bisulfite adduct, and by chemical reduction to indoleethanol and oxidation to indoleacetic acid. Bioassays indicated a minimum indoleacetaldehyde content in etiolated cotyledons of 0.7 mug per kg fresh weight. Tissue samples from all parts of both green and etiolated cucumber seedlings reduced exogenously supplied indoleacetaldehyde to indoleethanol.

7.
Plant Physiol ; 61(1): 107-10, 1978 Jan.
Article in English | MEDLINE | ID: mdl-16660220

ABSTRACT

Extracts of light-grown Cucumis sativus L. seedlings catalyzed the oxidation of indole-3-acetaldehyde to indole-3-acetic acid. No added cofactors were required. Inhibitor studies indicated that the enzyme is a metalloflavoprotein. While indole-3-aldehyde, benzaldehyde, and phenylacetaldehyde partially inhibited the oxidation of indole-3-acetaldehyde, suggesting that they may serve as alternative substrates, it is proposed that indoleacetaldehyde is the major substrate in vivo. 2,4-Dichlorophenoxyacetic acid strongly inhibited the indoleacetaldehyde oxidase activity, and it is proposed that this enzyme may be subject in vivo to feedback inhibition by indole-3-acetic acid. The enzyme was activated by brief heating or by treatment with mercaptoethanol.

9.
Plant Physiol ; 57(6): 850-4, 1976 Jun.
Article in English | MEDLINE | ID: mdl-16659584

ABSTRACT

Subcellular fractionation of cucumber (Cucumis sativus L.) seedlings was achieved, and two of the enzymes in the auxin biosynthetic pathway were localized. NADH-specific indoleacetaldehyde reductase activity was observed only in the cytosol fractions obtained from separated hypocotyl and cotyledon tissue. In contrast, a portion of the NADPH-specific indoleacetaldehyde reductase activity was associated with a microsomal fraction derived from these tissues. The NADPH-specific indoleacetaldehyde reductase was consistently found to be more firmly associated with the microsomal fraction derived from hypocotyls than with that from the cotyledons. These results indicate a division of the terminal steps of auxin biogenesis into at least two subcellular compartments.

10.
Plant Physiol ; 57(6): 886-9, 1976 Jun.
Article in English | MEDLINE | ID: mdl-16659591

ABSTRACT

Co(2+) promoted elongation of hypocotyl segments of light-grown cucumber (Cucumis sativus) seedlings. Time course and dose response data are presented and interactions with IAA, gibberellin, cyclohexanol, and cotyledons described. Segments without cotyledons responded to Co(2+) only if grown in gas-tight vessels with IAA added. When bases of cotyledons were ringed with an inhibitor of auxin transport, Co(2+) caused no growth promotion in the hypocotyl. Co(2+) prevented lateral swelling of hypocotyls treated with supraoptimal IAA. Removal of ethylene from the atmosphere reduced the Co(2+) response, but Co(2+) did not counteract the inhibitory effect of increased ethylene levels. These results are consistent with the hypothesis that Co(2+) promotes hypocotyl elongation by inhibiting ethylene production. The hypothesis was confirmed by a direct demonstration that Co(2+), at growth-promoting concentrations, powerfully inhibited ethylene production in the cucumber hypocotyl.

11.
J Biol Chem ; 251(4): 907-13, 1976 Feb 25.
Article in English | MEDLINE | ID: mdl-2607

ABSTRACT

In a continuing study of the biosynthetic pathway and regulatory mechanisms governing indole-3-acetic acid (auxin) formation, we report the isolation and initial characterization of three distinct indole-3-acetaldehyde reductases from cucumber seedlings. These enzymes catalyze the reduction of indole-3-acetaldehyde to indole-3-ethanol with the concomitant oxidation of NAD(P)H to NAD(P)+. Two of the reductases are specific for NADPH as second substrate, while the third is specific for NADH. The enzymes show a strong specificity for indoleacetaldehyde, with apparent Km values of 73mum, 130mum, and 400mum being calculated for the two NADPH-specific reductases and the NADH-specific reductase, respectively. Under no conditions of substrate concentration, incubation time, or assay method could the reverse reaction be observed. Chromatography on a calibrated Sephadex gel column led to estimated molecualr weights of 52,000 and 17,000 for the NADPH-specific reductases, while a value of 33,000 was obtained for the NADH-specific reductase. Both NADPH-specific reductases showed a pH optimum of 5.2 with a secondary optimum at 7.0, and both enzymes were activated by increasing ionic strength. The NADH-specific reductase showed a pH optimum of 7.0 with a secondary optimum at 6.1 and was slightly inhibited by increasing ionic strength.


Subject(s)
Aldehyde Oxidoreductases/metabolism , Plants/enzymology , Aldehyde Oxidoreductases/isolation & purification , Hydrogen-Ion Concentration , Kinetics , Osmolar Concentration , Sodium Chloride/pharmacology , Spectrophotometry , Structure-Activity Relationship
12.
Plant Physiol ; 54(4): 601-7, 1974 Oct.
Article in English | MEDLINE | ID: mdl-16658936

ABSTRACT

Cell-free extracts of cucumber (Cucumis sativus L. cv. National Pickling) seedlings were found to have amine oxidase activity when assayed with tryptamine as a substrate. Studies of the effect of lowered pH on the extract indicated that this activity was heterogeneous, and three amine oxidases could be separated by ion exchange chromatography. The partially purified enzymes were tested for their activities with several substrates and for their sensitivities to various amine oxidase inhibitors. One of the enzymes may be a monoamine oxidase, although it is inhibited by some diamine oxidase inhibitors. The other two enzymes have properties more characteristic of the diamine oxidases. The possible relationship of the amine oxidases to indoleacetic acid biosynthesis in cucumber seedlings is discussed.

13.
Plant Physiol ; 51(4): 739-43, 1973 Apr.
Article in English | MEDLINE | ID: mdl-16658401

ABSTRACT

We report the further characterization of indole-3-ethanol oxidase from cucumber seedlings. The effects of various inhibitors suggest that the enzyme may be a flavoprotein with a metal ion and sulfhydryl groups required for full activity. Indole-3-acetaldehyde, a product of the reaction, inhibits the enzyme. This inhibition is overcome by O(2) but not by indole-3-ethanol, indicating that the kinetic mechanism of the enzyme is a ping-pong Bi-Bi. The enzyme undergoes cooperative interactions with indoleethanol, yielding Hill coefficients as high as 2.96. Gibberellins are without effect on the enzyme, but it is inhibited by several acidic indoles possessing growth-promoting activity and by two synthetic auxins, 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid. Increasing concentrations of indoleacetic acid (IAA) brought about a slight reduction in the indoleethanol concentration producing halfmaximal velocity. Increasing levels of indoleethanol decreased the concentration of IAA required for half-maximal inhibition. At low concentrations of indoleethanol, low levels of IAA activated rather than inhibited. The effect of IAA was not overcome at higher levels of indoleethanol. These results may be interpreted as showing that IAA is a noncompetitive inhibitor which binds to that conformation of the enzyme which also binds indoleethanol. The significance of these interactions for the regulation of IAA biosynthesis is discussed.

14.
Plant Physiol ; 49(5): 716-21, 1972 May.
Article in English | MEDLINE | ID: mdl-16658035

ABSTRACT

Previous work in this laboratory has shown that cucumber (Cucumis sativus L.) seedlings contain large amounts, relative to other indolic compounds, of extractable indole-3-ethanol (IEt); tracer studies have established that IEt is metabolized to IAA. We have now succeeded in isolating an enzyme from these seedlings which catalyzes the oxidation of IEt to indole-3-acetaldehyde (IAAld). The identification of the product as IAAld was based on solvent partitioning of the free aldehyde and its bisulfite adduct and radiochromatography following incubation of enzyme with (14)C-IEt. A novel, quantitative colorimetric test for IAAld was also developed utilizing the Salkowski reagent. Partial purification of the enzyme was achieved by salt gradient chromatography on Bio-Rex 70, heating the preparation to 70 C, and chromatography on Sephadex G-150. This purification procedure yielded an enzyme activity purified in excess of 3000-fold, and studies on a standardized Sephadex column suggest a molecular weight of the enzyme of approximately 105,000. The reaction was found to proceed only aerobically; and, in the absence of other electron acceptors, O(2) appears to be reduced to H(2)O(2). The enzyme has nearly maximum activity from pH 8 to 11.

15.
Plant Physiol ; 46(4): 581-5, 1970 Oct.
Article in English | MEDLINE | ID: mdl-16657509

ABSTRACT

When intact etiolated 2-day cucumber (Cucumis sativus) embryos were treated with indoleacetic acid (IAA), gibberellin A(7) (GA(7)), or kinetin, chromatin derived from the embryonic axes exhibited an increased capacity to support RNA synthesis in either the presence or the absence of bacterial RNA polymerase. An IAA effect on cucumber RNA polymerase activity was evident after 4 hours of hormone treatment; the IAA effect on DNA template activity (bacterial RNA polymerase added) occurred after longer treatments (12 hours). GA(7) also promoted template activity, but again only after a prior stimulation of endogenous chromatin activity. After 12 hours of kinetin treatment, both endogenous chromatin and DNA template activities were substantially above control values, but longer kinetin treatments caused these activities to decline in magnitude. When chromatin was prepared from hypocotyl segments that were floated on a GA(7) solution, a GA-induced increase in endogenous chromatin activity occurred, but only if cotyledon tissue was left attached to the segments during the period of hormone treatment.Age of the seedling tissue had a profound influence on the chromatin characteristics. With progression of development from the 2-day to the 4-day stage, the endogenous chromatin activity declined while the DNA template activity increased.

16.
Plant Physiol ; 44(9): 1303-9, 1969 Sep.
Article in English | MEDLINE | ID: mdl-5379108

ABSTRACT

The conversion of tryptophan-(14)C to indoleacetic acid-(14)C in cucumber hypocotyls occurred under both sterile and non-sterile conditions. This conversion was not reduced under sterile conditions. The growth response of cucumber hypocotyl segments to exogenously supplied tryptophan was almost as great under sterile conditions as when contaminating micro-organisms were present. These data are consistent with the hypothesis that tryptophan is a normal precursor of indoleacetic acid in cucumber tissues. The conversions of tryptamine-(14)C and indoleethanol-(14)C to indoleacetic acid-(14)C also occurred under both sterile and non-sterile conditions. Indoleethanol-(14)C was formed from tryptamine-(14)C. Hypocotyl segment growth responses to tryptamine and to indoleethanol were not decreased under sterile conditions.


Subject(s)
Plant Growth Regulators/biosynthesis , Tryptophan/metabolism , Carbon Isotopes , Chromatography, Thin Layer , Indoleacetic Acids/biosynthesis , Vegetables
18.
Plant Physiol ; 43(8): 1259-63, 1968 Aug.
Article in English | MEDLINE | ID: mdl-16656909

ABSTRACT

Two or more kinetically distinguishable populations of phytochrome molecules were observed in living tissues of oat, pea, maize, and cauliflower, as well as in extracts of oat. At least 3 different populations occurred in cauliflower florets, while 2 were observed in each of the other species. In extracted oat phytochrome, the relative proportions of the 2 forms remained constant during successive stages of purification. The physiological significance of this multiplicity of forms remains unclear.

19.
Plant Physiol ; 43(3): 454-6, 1968 Mar.
Article in English | MEDLINE | ID: mdl-16656787
20.
Plant Physiol ; 42(8): 1091-3, 1967 Aug.
Article in English | MEDLINE | ID: mdl-16656619

ABSTRACT

Indoleethanol-(14)C was applied to intact cucumber seedlings and to hypocotyl segments. The presence of indoleacetic acid-(14)C in tissue extracts was demonstrated by thin layer radiochromatography. There was no evidence of conversion of indoleacetic acid to indoleethanol. It is suggested that the growth-promoting activity of indoleethanol is due to its conversion to indoleacetic acid.

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