Sephadex-Gelfiltration von Huminsäuren und deren Gehalt an Aminosäuren

Gel filtration on Sephadex of humic acids and their content of amino acids

• 1 Brown humic substances from the A_h of an iron-humus podzol were separated on Sephadex G 25 into three fractions. The first fraction (Ve/Vo = 1.0–1.5) has the lowest value of Q 4/6 (5.0–8.0), the second the highest Q 4/6 (10.0–12.0) and the third a middle one (8.0–10.5). The adsorption effect may take place during separation.
• 2 The asymmetric form of the integral elution curves of the first fraction indicated that the humic substances are a set of particles with different size. The separation is influenced by diffusion into the pores of gel matrix.
• 3 In the first fraction were determined 16, in the second 13 and in the third 10 amino acids.
• 4 The titration curves of the first fraction (after separation on G 25) indicated that the rate of pH change with alkali added becomes its maximum at pH 6.5–7.5 at different ionic strengths.
• 5 Dialysed humic acids (H⁺ form) were fractionated on G 75. The alkali consumption up to pH 7.5 in the eluate shows that small amounts of mineral acids increase the conductivity of the solution. Their V_e is lower than that of the second fraction of humic acids. Therefore it is impossible to determine the alkali consumption by the second fraction and by the humic acids as a whole without their total desalting.

     

Wechselwirkungen von Huminstoffen mit Aminosäuren

Interaction of Humic Acid with Amino Acids By means of the charge-transfer complexes between p-benzoquinone and a number of amino acids, this possible mechanism of the reaction of humic acids with amino acids has been pointed out in principle. The mechanism has been confirmed for the humic acids by the absorption spectra in the ultraviolett and visible range and an increase of the dissoziation of the phenolic hydroxyl of the tyrosine molecule. The quantitative aspect of this binding has been dealt with by gelfiltration in a state of equilibrium. 70 μmol of tyrosine were found to be bound by one gram of a synthetic humis acid.     

Extraktion freier Aminosäuren aus Pilzsporen (Phycomyces blakesleeanus)

Extraction of free amino acids from fungal spores (Phycornyces blakesleeanus) Because extraction conditions are crucial for the reliability of biochemical analysis of fungal spore materia1, comparative investigations on methods were conducted, using the amount of free amino acids as a parameter of exhaustive extraction. It was found that optimal conditions are: Extraction in a Soxhlet apparatus with methanol as extracting medium (for 8 hours under reduced pressure and 40°C boiling temperature) or treatment with ice-cold perchloric acid (10 % for 30 minutes) or trichloroacetic acid (10 % for 30 minutes). A pretreatment of the material by desintegration was not necessary. Extraction with hot water (70 or l00T) or with ethanol, propanol, butanol, 3,3 %perchloric or trichloroacetic acid proved to be inappropriate. All of the common amino acids were detected in the extracts except proline and phenylalanine. A few amino acids make up the majority of the pool (glutamic acid, glutamine, aspartic acid, asparagine, alanine and y-butyric acid). These amino acids comprised about 80% of the total intracellular pool (ca. 12000 moles/l00mg spores) and account for nearly 2% of the spore dry weight. Sacrosine, probably being present in considerable amounts, could not be determined quantitatively.     

Ammoniakemissionen aus alternden Pflanzen und bei der Zersetzung von Ernterückständen

Ammonia emissions from senescing plants and during decomposition of crop residues NH₃ emissions from plant stands, measured under simulated environmental conditions with the wind tunnel method, ranged between 0.8 and 1.4% of the N content of the shoot, equivalent to 1.1 to 2.9 kg NH₃-N ha^?1. The highest emissions were observed in faba beans whereas the emissions in winter wheat, spring rape and white mustard were lower. The total NH₃ emissions were not affected by removing a part of the ears (sink reduction), but emissions occurred earlier, as did the plant senescence. This suggests that the NH₃ emissions are closely related to senescence. NH₃ emissions from decomposing crop residues ranged from 0.9 to 3.7% of the N content. The emissions from sugar beet leaves and potato shoots with high water content reached from 8.6 up to 12.6 kg N ha^?1, whereas the emissions from field bean straw with high dry matter and N content were relatively low. (3.1 kg N ha^?1, or 0.9% of the N content). The NH₃ emissions from sugar beet leaves were reduced by 81% by ploughing and 63% by mulching.     

Schwermetall- und Nährelementgehalte von Pflanzen und Bodenproben schwermetallhaltiger Halden im Raum Bleiberg in Kärnten (Österreich) I. krautige Pflanzen

Heavy metal- and nutrient contents of plants and soil samples from metal liferous waste dumps in Bleiberg (Carinthia, Austria). I. herbaceous plants Lead and zinc concentration in the fine fraction (< 0,2 mm) of mine dump material were twice as high as in coarser fraction (2–0,2 mm) (table 1). Due to high metal levels in roots of several mine dump plants (table 3) interactions between plants and soil-microorganisms are assumed. Furthermore root originating exsudates (organic acids) are probably responsible for an increase in heavy metal availability in soil in spite of a general high pH of soil solution. The low mobility of lead within intact plants is caused by a selective affinity of this metal to cell wall pectines. On the other hand a physiological barrier (endodermis/pericycel) in primary roots of these plants is assumed, which partly prevents lead from upward transport into the shoots. Heavy metal compartmentation may be part of a tolerance mechanism diminishing a surplus of toxic metals within plant metabolism.     

Einfluß der Kaliumernährung auf die Wachstumsrate,den Gehalt an Kohlenhydraten und die Wasserretention von jungen Weizenpflanzen

The effect of potassium nutrition on growth rate, carbohydrate content, and water retention in young wheat plants The effect of potassium supply on the water content, growth rate, and content of carbohydrates has been studied in young wheat plants during a period of 22 days. Inadequate K⁺ supply resulted in a lower water content (water/g dry matter) and a decreased growth rate as compared with plants sufficiently supplied with K⁺. During the first days of the experimental period no major difference in the content of carbohydrates (glucose, fructose, sucrose, starch, fructosans) was found between both treatment. In the following days, however, the carbohydrate contents in the plants insufficiently supplied with K⁺ were significantly higher than in the plants with an adequate K⁺ nutrition. At the end of the experimental period a reverse pattern was found, the carbohydrate contents of the plants well fed with K⁺ were higher as compared with the plants with an insufficient K⁺ supply. It is concluded that K⁺ deficiency at first affects water retention and turgor. A reduced turgor results in a decreased growth rate which in return may lead to an accumulation of carbohydrates. Later at advanced K⁺ deficiency also the synthesis of carbohydrates is affected.     

Die Reaktion von aromatischen Hydroxycarbonsäuren mit N-Methyl-N-Nitroso-N′-Nitroguanidin und N-Methyl-N-Nitrosoharnstoff

Reaction of Aromatic Hydroxycarboxylic Acids with N-Methyl-N-nitroso-N′-nitroguanidine and with N-methyl-N-nitrosourea The phenols affect the mutagenity of nitroso compounds. Using polarography and voltammetry the redox properties of phenols and N-nitroso compounds were investigated. Changes in half-wave potentials of N-methyl-N-nitrosourea and N-methyl-N-nitroso-N′-nitroguanidine in the presence of gallic acid and in the anodic waves of gallic acid were detected in presence of MNNG. The interaction of the above nitroso compounds with phenols basing on the formation of molecular complexes is discussed.     

Einfluß von Fe- und Mo-Mangel auf den Ionengehalt mono-und dikotyler Pflanzen unterschiedlicher Chloroseanfälligkeit

Effect of Fe- and Mo-deficiency on the ion content of monocotyledones and dicotyledones with different susceptibility to chlorosis. In pot experiments with maize, sunflower and gras the influence of Fe- and Mo-deficiency on the concentrations of inorganic cations (K, Ca, Mg), anions (NO₃, PO₄, SO₄, Cl) and caboxylates (sum of citrate, malate, malonate, fumarate and aconitate) in the plants was studied. Fe-deficiency increased the excess of inorganic cations over anions (C-A) and the content of carboxylates, especially of citric acid, in sunflower and maize with the highest differences in sunflower plants. The increased C-A-values were due to higher K-, Ca- and Mg-concentrations and not to reduced concentrations of anions in the Fe-deficient plants. In the varieties of maize and sunflower with high susceptibility for Fe-chlorosis, mainly the K-content of the Fe-deficient plants was raised. Mo-deficiency lead to an increase of carboxylates in sunflower, although in some cases the cation excess (C-A) was lowered. But even in these cases, the K-, Ca and Mg-content of Mo-deficient plants was raised. Knaulgras, which was sensitive to Mo-deficiency, had higher C-A-values (K-, Ca-, and Mg-contents) and increased concentrations of carboxylate in Mo-deficient plants, similar to maize with Fe-deficiency. Both Fe- and Mo-deficient plants can be characterized by increased contents of K, Ca and Mg and a higher carboxylate concentration.     

Carboanhydrase-Aktivität und extrahierbares Zink als Maßstab für die Zink-Versorgung von Pflanzen

Carboanhydrase activity and extractable zinc as indicator of the zinc supply of plants 1. Maize, millet, tobacco, sugar-beet and vine were grown under controlled environmental conditions with different zinc concentrations in the substrate. Plant growth, zinc and phosphorus content of the dry matter, extractable zinc and carbonic anhydrase activity in the leaves were measured. 2. Increasing supply of zinc to strongly zinc deficient plants resulted in a marked increase of growth, whereas total zinc content of the leaf dry matter was only slightly and carbonic anhydrase activity was strongly affected. In extremely zinc deficient plants carbonic anhydrase activity was close to zero even though the zinc content of the dry matter was higher than 10 μg/g. Therefore carbonic anhydrase activity appears to reflect the amount of physiologically active zinc in the leaf tissue. It seems to be useful to decide critical cases even at latent zinc deficiency. 3. The P/Zn ratio is also an indicator of zinc supply when plants are extremely zinc deficient, but not under latent deficiency. Moreover the P/Zn ratio can vary in a wide range when plants are well supplied with zinc. 4. The zinc concentration of aqueous leaf extracts increased with increasing level of zinc. 2-3 μg Zn/ml extract were found to be sufficient for all plant species used and all conditions of growth applied. Apparently, the Zn-concentration of the aqueous leaf extract is a better parameter of zinc supply than total zinc or carbonic anhydrase activity which, in addition, is much more difficult to determine.     

Mobilität und Pflanzenverfügbarkeit von Phosphor aus organischen und anorganischen Formen in der Rhizosphäre von Lolium perenne

Mobility and availability of phosphorus from organic and inorganic forms in the rhizosphere of Lolium perenne 1.) In pots (sandwich-technique according to Helal and Sauerbeck), where the soil (A_p-horizon of an Alfisol-Udalf from loess) was separated into a root chamber and an outer chamber (up to 10 mm away from the root chamber), the phosphorus (P) availability of super-P, rock-P (Hyper-P) and organic P [myo-inositol-2-mono-P di(cyclohexylammonium) salt] was studied. P was applied at a rate of 50 mg P kg^?1 soil only in the outer chamber. This P fertilization resulted in significant increase of CAL- and water-extractable P in the treatment with organic P and super-P compared to the P₀ treatment. During 6 cuts of Lolium perenne organic P showed the same effect on the P-uptake of plants as super-P. Compared to the treatment without P, rock-P had no effect on the P-uptake. The higher P-uptake of Lolium perenne both in the super-P- and organic P-treatment was reflected at the end of the experiment only by the CAL-P content differences between root chamber and outer chamber. The highest activity of acid phosphatase, measured in air dried soil was found in the root chamber of the organic P treatment The content of EUF extractable organic P was significantly higher in the root chamber of the treatments with super-P and organic P than in the P₀- and rock-P-treatment. 2.) The P elution was studied with 2 soils (A_p-horizon of an Alfisol-Udalf from loess pH: 6.4; A_h-horizon of a basaltic brown soil pH: 5.4) under lab conditions in columns. In the super-P-and organic P-treatment leached P was mainly inorganic. In the soil with low pH value (5.4), P was leached in the treatment with super-P or organic P in a higher amount of organic P than in the soil with pH 6.4. The results of this experiment do not show in which form the applied organic P was moved to the roots or displaced in the soil.