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Abstract: The genesis of a 40-cm-thick buried Holocene humic soil horizon in a 6-m-high sequence near Towada volcano, Japan, was examined by dating stable, plant-derived humin particles by AMS-based radiocarbon (14C), and by analyzing stable carbon isotope ratios (δ13C), phytolith composition, and soil chemical properties. The AMS dating yielded calibrated ages ranging from 7570–7679 to 6180−6313calyr BP. We obtained a strong correlation (r=0.99, ***p<0.001) between sample depth and the mean age. The (now buried) humic soil was formed by the incremental accumulation of tephric loess and aeolian dust at a constant rate of ~30mm per century for at least 1200years. Whilst the soil surface was slowly rising, graminaceous vegetation was supplied at a constant rate so that developmental upbuilding pedogenesis ensued. The soil was buried and isolated by the fall of the Towada-Chuseri tephra about 6200calyr BP. Thus the tephra-soil sequence near Towada volcano represents both developmental and retardant upbuilding pedogenesis. [Copyright &y& Elsevier]

Copyright of Revista de la Sociedad Química del Perú is the property of Sociedad Quimica del Peru and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We isolated an antimicrobial compound from the aerial tissue of Geranium carolinianum and identified it as ethyl 3, 4, 5-trihydroxy benzoate (ethyl gallate) by 1H-NMR and 13C-NMR and gas chromatography–mass spectrometry. The antimicrobial activity of ethyl gallate against three potato pathogens was assayed by the paper disk method. The activity against Ralstonia solanacerum, Streptomyces scabies, and Streptomyces acidiscabies was observed at concentrations >200, >300, and >300 µg disk−1, respectively. These results suggest that the antimicrobial activity of Geranium carolinianum against soil-borne plant disease pathogens is partly related to ethyl gallate. [ABSTRACT FROM AUTHOR]

Mineral imbalance in high-input agricultural ecosystems has become an acute concern in many developed countries. Relapse into low-input agricultural ecosystems, however, will cause mineral stresses to crops, resulting in reduced food productions. Under such natural soil conditions, some endemic plants can tolerate the mineral stresses because they have evolved to adapt to the stresses. Numerous studies have been conducted to clarify the chemistry of the mineral elements of interest in rhizosphere and to utilize the tolerant mechanisms in plants. In this chapter, the authors reviewed the research progress on molecular scale mechanisms of Fe-deficiency, Al-toxicity, and P-deficiency stresses in soils and their tolerances by plants. In low Fe-availability conditions, two Fe-acquisition mechanisms of plants have been clarified: enhanced Fe dissolution in rhizosphere by secreted proton/reductants/chelators followed by reduction of Fe3+ to Fe2+ and specific uptake of Fe2+ (Strategy I) and Fe dissolution by secreted hexadentate Fe3+-transporting molecule (phytosiderophore) by forming Fe3+-phytosiderophore complex followed by specific uptake of the complex (Strategy II). Two tolerant mechanisms against high Al-toxicity of soils have been reported: exclusion of Al from cytoplasm (exclusion mechanism) and detoxification of Al in plants (internal detoxification mechanism). Phosphorous acquisition mechanisms of plants from low P-availability soils would be (1) alteration of root architecture, (2) secretion of organic acids, (3) secretion of phosphatase, and (4) enhanced expression of P transporter on roots. Some of the molecular mechanisms for the expression of the tolerances and their application to the genetic improvement are also reviewed. [ABSTRACT FROM AUTHOR]

14C ages and δ13C were examined for sclerotium grains to elucidate the characteristics of these grains distributed in forest soils. The ages of the grains from surface A horizons and buried A horizons were ca 100–200 bp and ca 300–1,200 bp, respectively. In comparison with humic acid extracts, the 14C ages were in the increasing order: humic acid fraction < humic acid Pg fraction < sclerotium grains. The δ13C values for sclerotium grains in surface A horizons and buried A horizons were approximately −31‰ to −28‰, and these values were approximately 2–4‰ smaller than those of humic acids and soils. The C content of the grains had a tendency to decrease with increasing 14C ages, while the C content of humic acid was constant with age. The 14C ages of sclerotium grains indicate the individual age of grain formation, which are more likely to assign closer ages to the beginning of soil forming than the 14C ages of humic acid. The low δ13C values for sclerotium grains have presumably originated from characteristically biological organics, which may be protected from attack in soils because of their structure. [ABSTRACT FROM AUTHOR]

Abstract: Three representative allophanic Andisols in Japan were evaluated by solid-state 13C, 27Al, and 29Si nuclear magnetic resonance (NMR) and stable isotopic ratio of carbon (δ13C). The solid-state cross polarization magic angle spinning (CPMAS) 13C NMR spectra were effective in characterizing crude soil C without any chemical treatment when soil C content was >100 g C kg−1. Aliphatic, O-alkyl, and carbonyl C were relatively abundant in the uppermost horizons, whereas aromatic C was concentrated in the subsurface horizons, showing its persistence and tolerance to degradation in subsurface horizons. Contribution ratios of C4-plant-derived C (mainly from Miscanthus sinensis) on the total CRC4 which were evaluated from δ13C value, were 35% to 42%, 59% to 62%, and 50% to 53% in subsurface horizons, and 12%, 23%, and 48% in uppermost horizons, for the three soils. The decline in CRC4 values in the uppermost horizons could be an effect of recent vegetation. Solid-state 27Al and 29Si NMR revealed that most part of the tetrahedral Al in volcanic glass had already weathered into octahedral Al and a large amount of allophanic constituents (allophane, imogolite, allophane-like constituents including protoimogolite) was formed in B horizon within the past 25,000 14C y. Allophanic constituents determined by 29Si NMR were compared with those dissolved by acid-oxalate, and differences between them were discussed. [Copyright &y& Elsevier]

Abstract: Fulvic acids play an important role in the behavior of metals and hydrophobic organic chemicals in soil and water environments. The isolation and purification of the fulvic acids have been difficult to achieve, however, because these compounds are soluble in both alkaline and acidic solution, resulting in difficulty of dehydration and demineralization. We propose here a new procedure for isolating fulvic acids as precipitates. Our procedure includes pH-adjustment of the fulvic acid solution to weakly acidic to neutral pH range (4 to 7). In an Andisol, recoveries of the fulvic acids we prepared by precipitation at equilibrium pH of 5.0 were 86% (dissolved total organic carbon basis) and 97% (absorbance basis, 400 nm), whereas recoveries of fulvic acids adsorbed on XAD-8 resin (hydrophobic fulvic acids) were 14% and 28%, respectively. Recoveries of the fulvic acids were further increased in our procedure by adding Al. The mechanism forming the precipitates includes a complexation reaction of carboxylic groups of the fulvic acids with Al (ligand exchange reaction); this mechanism is identical to that for the retention of fulvic acids in many soils. Therefore, it is likely that our preparation procedure is appropriate for separating the fulvic acids stabilized in soils. Solid-state cross polarization and magic angle spinning 13C nuclear magnetic resonance spectra showed that the fulvic acids prepared by our precipitation procedure were relatively rich in O-alkyl carbons and poor in aromatic and alkyl carbons compared with those forms from the hydrophobic fulvic acids adsorbed on XAD-8 resin. A new scheme for preparing the hydrophobic and hydrophilic fulvic acids is also proposed here. The hydrophilic fulvic acids are likely to maintain high solubilities in water even after the formation of complexes with metals and may influence on their behavior. [Copyright &y& Elsevier]

Copyright of Canadian Journal of Microbiology is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: Cyanamide is a multifunctional agrochemical used, for example, as a pesticide, herbicide, and fertilizer. Recent research has revealed that cyanamide is a natural product biosynthesized in a leguminous plant, hairy vetch (Vicia villosa). In the present study, gas chromatography–mass spectrometry (GC–MS) equipped with a capillary column for amines was used for direct quantitative determination of cyanamide. Quantitative signals for (14N2)cyanamide, (15N2)cyanamide (internal standard for stable isotope dilution method), and m-(trifluoromethyl)benzonitrile (internal standard for correcting errors in GC–MS analysis) were recorded as peak areas on mass chromatograms at m/z 42 (A 42), 44 (A 44), and 171 (A IS), respectively. Total cyanamide content, (14N2)cyanamide plus (15N2)cyanamide, was determined as a function of (A 42 + A 44)/A IS. Contents of (14N2)cyanamide and (15N2)cyanamide were then calculated by multiplying the total cyanamide content by A 42/(A 42 + A 44) and A 44/(A 42 + A 44), respectively. The limit of detection for the total cyanamide content by the GC–MS analysis was around 1ng. The molar ratio of (14N2)cyanamide to (15N2)cyanamide in the injected sample was equal to the observed A 42/A 44 value in the range from 0.1 to 5. It was, therefore, possible to use the stable isotope dilution method to quantify the natural cyanamide content in samples; i.e., the natural cyanamide content was derived by subtracting the A 42/A 44 ratio of the internal standard from the A 42/A 44 ratio of sample spiked with internal standard, and then multiplying the resulting difference by the amount of added (15N2)cyanamide (SID-GC–MS method). This method successfully gave a reasonable value for the natural cyanamide content in hairy vetch, concurring with the value obtained by a conventional method in which cyanamide was derivatized to a photometrically active compound 4-cyanimido-1,2-naphthoquinone and analyzed with reversed-phase HPLC (CNQ-HPLC method). The determination range of cyanamide in the SID-GC–MS method was almost the same as that in the CNQ-HPLC method; however, the SID-GC–MS method was much simpler than the CNQ-HPLC method. [Copyright &y& Elsevier]

Focuses on sex pheromone and related compounds in the Ishigaki and Okinawa strains of the tussock moth Orgyia postica (Walker). Discovery of two distinct electroantennographycally active components, A and B, and a weakly active component C in a solvent extract from virgin females of the Ishigaki strain of the tussock moth; Finding of components A, B, and C in the extract of the females at 4.0, 0.5, and 4.0 ng/female respectively; Confirmation that the attractant pheromone of O. postica of the Ishigaki strain is also (11S,12S)-1; Discussion of the attractiveness of the components to the males on both Japanese islands in the context of the activity and possible evolution of pheromonal polymorphism in the species.

We investigated the influences of humic acid on the removal of Al tridecamer (Al13) from a hydroxyaluminum (HyA) solution at various humic acid/Al ratios. The Al species contained in the solution were analyzed by using a liquid-state 27Al-NMR and an atomic absorption spectrometer and fractionated into three Al species: (i) Al13, (ii) Al monomer and dimer (AlSYM), and (iii) other undefined species including aggregated/precipitated Al (AlNON). By the addition of humic acid to the HyA solution, the concentration of Al13 was rapidly decreased within 0.007 d (10 mm). The decrease in Al13 and the increase in AlNON were more pronounced at a higher humic acid/Al ratio. When the molar ratio of humic acid carboxylic groups to Al exceeded 0.8, Al-3 was undetected from solution within 0.007 d. The formation of Al13-humic acid complexes and the aggregation/precipitation of those complexes were a predominant mechanism in removing aqueous Al13 at the early stage of the reaction. Approximately 10 mol of carboxylic groups in humic acid were required to remove 1 mol of Al13 from the HyA solution. Aqueous AID had greater preference in precipitating with humic acid than AlSYM. After 5 to 570 d of aging, the concentration of Al13 and AlNON also decreased and increased, respectively, both in the presence and absence of humic acid. In conclusion, aqueous Al13 would not exist in soil solution under a high humic acid condition. [ABSTRACT FROM AUTHOR]

In order to elucidate the allelopathic effect of leaf litter leachates under laboratory conditions, a modified ‘sandwich method’, which places leaves between two layers of agar, was used. Fifty mg of leaves was used per 10 cm2 cell. Agar concentrations at 0.5–1.0% were the best for gel support in determining radicle and hypocotyl elongation of lettuce. The optimum incubation time for bioassay was three days after imbibition onset. Among 20 typical tree species in Asia, Cymbopogon citratus and Derris scandens showed the strongest inhibitory activity determined by the sandwich method, followed by Piper betle, Tamarindus indica, and Gliricidia sepium. This bioassay seems to be a reliable method for screening allelopathic activity from leaf litter leachates. [ABSTRACT FROM AUTHOR]

A sex pheromone component of Pseudococcus cryptus has been isolated and identified. The crude pheromone extract obtained by airborne collection was fractionated by liquid chromatography (LC) on Florisil, and further purified by high performance liquid chromatography and preparative Gas Chromatography (GC). The pheromone component was shown to be an ester, the alcohol part of which was identical to the known alcohol moiety of the pheromone of Planococcus citri. The chemical structure was determined to be 3-isopropenyl-2,2-dimethylcyclobutylmethyl 3-methyl-3-butenoate by MS and `H NIMR analyses. The absolute configuration of the pheromone was assigned as (IR,3R) by comparison of the retention lime of the alcohol derived from the P. cryptus pheromone with those of the alcohol derived from P. citri pheromone, and a synthetic sample of alcohol enriched in the (1 R,3R)-enantiomer, using a chiral GC stationary phase. The structure of the pheromone was confirmed by synthesis, and by bioassays in a glasshouse. [ABSTRACT FROM AUTHOR]

Cyanamide was isolated from the leaves and stems of hairy vetch (Vicia villosa), guided by plant growth inhibitory activity against lettuce (Lectuca sativa) seedlings. A large proportion of the inhibitory activity in the crude extract was explained by the presence of cyanamide, suggesting it to be a possible allelochemical in this species. The amount in a 9-day-old seedling, which had been grown without nutrients, reached approx. 40 times that of a nongerminated seed, demonstrating cyanamide biosynthesis in the seedlings. This is the first report on the isolation of a possible allelochemical from hairy vetch and also of the finding of cyanamide as a natural product. [ABSTRACT FROM AUTHOR]

L-Canavanine is a nonprotein amino acid contained in jack bean [Canavalia ensiformis (L.) DC] and shows a plant inhibitory effect. The inhibitory effect was determined by an immersion test and a microdrop test that employed rice seedlings. L-Canavanine inhibited elongation of the second leaf sheath of rice seedlings more than other natural bioactive substances, such as salicylic acid and cinnamic acid. The modified microdrop test revealed that the mode of action of L-canavanine had no relation to gibberellin synthesis. In the microdrop test, the inhibitory effect of L-canavanine was decreased by simultaneous addition of L-arginine, an analog of L-canavanine. Free amino acid analysis of rice shoots clearly showed that L-canavanine induced an unusual accumulation of L-arginine. However, accumulation of L-arginine did not cause the inhibitory effect on plant growth. These results suggest that the mechanism of inhibition of L-canavanine is closely related to the inhibition of arginine metabolism. [ABSTRACT FROM AUTHOR]

The forms of Al for uptake by the roots and translocation from the root to the shoot were investigated in a buckwheat (Fagopyrum esculentum Moench, cv. Jianxi) that accumulates Al in its leaves. The Al concentration in the xylem sap was 15-fold higher in the plants exposed to AlCl3 than in those exposed to an Al-oxalate (1:3) complex, suggesting that the roots take up Al in the ionic form. The Al concentration in the xylem sap was 4-fold higher than that in the external solution after a 1-h exposure to AlCl3 solution and 10-fold higher after a 2-h exposure. The Al concentration in the xylem sap increased with increasing Al concentration in the external solution. The Al uptake was not affected by a respiratory inhibitor, hydroxylamine, but significantly inhibited by the addition of La. These results suggest that Al uptake by the root is a passive process, and La3+ competes for the binding sites for Al3+ on the plasma membrane. The form of Al in the xylem sap was identified by 27Al-nuclear magnetic resonance analysis. The chemical shift of 27Al in the xylem sap was around 10.9 ppm, which is consistent with that of the Al-citrate complex. Furthermore, the dominant organic acid in the xylem sap was citric acid, indicating that Al was translocated in the form of Al-citrate complex. Because Al is present as Al-oxalate (1:3) in the root, the present data show that ligand exchange from oxalate to citrate occurs before Al is released to xylem. [ABSTRACT FROM AUTHOR]

Presents a study which investigated aluminum speciation in aluminum-silica solutions and potassium chloride extracts of acidic soils. Methodology employed to differentiate chemical species of Al in soil solutions; Utilization of nuclear magnetic resonance (NMR) technique to conduct study; How NMR was applied; Findings of study.