Considerations on the interaction of ergons and their “substrates”

Veldstra, H.

doi:10.1016/0006-3002(47)90148-0

Cited by 29 publications

(7 citation statements)

References 21 publications

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“…Auxin is known to exist in the plant in the form of complexes (see van Overbeek, 19443). An explanation, similar in principle to this, is given by Veldstra (1947), who postulated the necessity of a cell lipoid in which auxins are supposed to be adsorbed and from which they exert their actions (see $$ IV (3) and V (4)).…”

Section: The Relationships Of Auxin T O Cell Metabolism ( I ) Growth mentioning

confidence: 81%

“…He was careful to point out that in this case the side chain is free to rotate and that this model does not represent a static configuration. It does, however, 'point to the possibility of an ideal position, the average statistical occurrence of which in strongly active compounds will be more frequent than in weakly active ones ' (Veldstra, 1947). This is presumably due to the prevention by the ring of complete rotation through 360".…”

Section: Trans-acidmentioning

confidence: 91%

“…Passing to a consideration of the side chain and the spatial configuration of the -COOH group, contemplations on Stuart models of active and inactive isomers led to the generalization that activity was strongly correlated with a position of the carboxyl group perpendicular to the plane of the ring (Veldstra, 1947). Such effects of the position of this group were well illustrated by the compound tetralydeneacetic acid which exists in the following cis-and trans-forms:…”

Section: ( 2 ) the Carboxyl Groupmentioning

confidence: 99%

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The Mechanism of Auxin Action

Audus¹

1949

Biological Reviews

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Summary 1. The article deals mainly with the last decade, although earlier work is briefly surveyed. 2. In general an effect of auxins in increasing cell wall extensibility has been verified, although there is no consistent correlation of growth rate with either elastic or plastic extensibility. There is a general tendency to regard the older methods of measuring extensibilities as too drastic and therefore misleading. 3. Two phases in cell elongation have been recognized, namely, an initial phase of pure wall stretching and a subsequent phase of wall growth by intussusception. Auxins may stimulate the first phase by increasing the swelling capacity of the intermicellar colloids (pectins) through the intermediary of the living protoplasm. The phase of intussusception may also be affected. Most recent theories suggest that these actions are effected by a disturbance of the intramolecular forces concerned in the formation and maintenance of the molecular lattice of the young cell wall (Diehl et al., Burström). 4. The maintenance of cellular osmotic pressures during active elongation has suggested an active solute uptake mediated by an auxin‐augmented respiratory process as the cause of cell elongation (Commoner). The results do not justify these conclusions. 5. The early claims of J. Bonner of a stimulation of respiration by auxin in Avena coleoptiles have been verified under certain experimental conditions. It seems possible that the degree of this stimulation may be influenced by the presence of various components of the Gyorgyi C4 dicarboxylic acid respiration cycle, which occurs in Avena coleoptiles. The use of monoiodoacetic acid as a differential inhibitor is misleading and results so far afford no proof of the action of auxins as a coenzyme in the C4‐acid cycle. 6. Auxin has no effect on the in vitro activity of a wide range of dehydrogenases extracted from Avena coleoptiles or on catalase and some plant oxidases. The heightened dehydrogenase activity of auxin‐treated coleoptiles may be due to an in vivo activation (Berger & Avery) or to an active enzyme synthesis. 7. The production of simple sugars from carbohydrate reserves after auxin application is not due to an activation of diastase or to its ‘elution’ by auxin from a protective colloid. This shift in the starch → sugar equilibrium is probably secondary to the main action of auxin. 8. The original postulates of Koepfli, Thimann & Went concerning the minimum molecular requirements for auxin activity have been verified by all recent work. Most evidence supports the view that auxin is effective only in the undissociated state and not as an anion. It seems unlikely from polarographic investigations that auxins act as respiratory coenzymes by virtue of a reversible oxido‐reduction of the essential double bond in the ring. Physiological activity is probably associated with an essential high (lipophilic) surface activity of the ring and its double bond(s), the polar ‐COOH group being most effective when orientated perpendicular to the plane of this ring. 9. A...

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Section: The Relationships Of Auxin T O Cell Metabolism ( I ) Growth mentioning

confidence: 81%

Section: Trans-acidmentioning

confidence: 91%

Section: ( 2 ) the Carboxyl Groupmentioning

confidence: 99%

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The Mechanism of Auxin Action

Audus¹

1949

Biological Reviews

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“…The molecular shape of a given isomer may determine the amount of the compound which can penetrate the root (1,33). Reactions may occur at the surface of the cell, however, which obviate the necessity of penetration (24,35,44).…”

Section: Discussionmentioning

confidence: 99%

“…The following compounds were dissolved in water and applied in concentrations ranging from 10-6 to 10-2 M to Kimpack paper treated with BHC: acetylcholine chloride, adenylic acid, beryllium sulphate, cysteine chloride, desoxyribose nucleic acid and ribose nucleic acid, dimethylamine, D-glucose, D,L-glyceraldehyde, ethanol and calcium chloride mixtures, i-inositol, iodoacetic acid, magnesium chloride, octanoic acid, phloridzin, sodium arsenate, sodium arsenite, sodium diethyldithiocarbamate, sodium fluoride, sodium pyrophosphate, thiamine hydrochloride and 2,4-dinitrophenol (10,15,24,27,29,42,44). All solutions were adjusted to a pH of 6.0 with th, exception of iodoacetic acid and sodium diethyldithiocarbamate which were used at a pH of 5.0 and 7.5, respectively.…”

Section: Methodsmentioning

confidence: 99%

Inhibition of Growth by Benzene Hexachloride Isomers and Protective Effect of Glucose as Measured by Cell Counting Technique

Hopkins

1952

Plant Physiol.

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Trichloroacetic acid in the foliage of forest trees

Frank¹,

Vincon²,

Reiss³

et al. 1990

J. High Resol. Chromatogr.

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Trichloroacetic acid (TCA) is an atmospheric oxidation product substances, and has been identified in chlorinated Waste [ l o ] and of airborne C2-chlorocarbons and a widespread air pollutant. It drinking waters [ 11, 121. TCA was used as an agricultural was widelv used as a herbicide in the fifties and sixties, in some herbicide in the fifties and sixties 1131.countries, still today. It occurs in the foliage of conifers and deciduous trees of mountain forests in Germany, e.g. the Black Forest, the Northern Alps or the Erzgebirge. Quantitative determination in the ppb-range is achieved by gas chromatography using thick film capillary columns and electron-capture detection. The levels in spruce needles at two forest sites correlate with the extent of needle loss.The data are supportive of the hypothesis that TCA is causally involved in the induction of mountain forest decline.

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Considerations on the interaction of ergons and their “substrates”

Cited by 29 publications

References 21 publications

The Mechanism of Auxin Action

The Mechanism of Auxin Action

Inhibition of Growth by Benzene Hexachloride Isomers and Protective Effect of Glucose as Measured by Cell Counting Technique

Trichloroacetic acid in the foliage of forest trees

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