Variations in the soil microbial community composition of a tropical montane forest ecosystem: Does tree species matter?

We investigated tree species effects on the soil microbial community in the tropical montane forest on Mt. Kinabalu, in Malaysian Borneo. We investigated microbial composition (lipid profile) and soil physicochemical parameters (pH, moisture, total C, N and phenolics concentration) in top 5-cm soils underneath two conifers (Dacrycarpus imbricatus and Dacrydium gracilis) and three broad-leaves (Lithocarpus clementianus, Palaquium rioence and Tristaniopsis clementis). We found that the primary difference in microbial composition was between conifer versus broad-leaves. The abundance of specific microbial biomarker lipids correlated with soil pH, total C and N. We conclude that tree species have significant impacts on the soil microbial community through their effects on soil pH, total C and N.     

Insecticidal and neuroblocking potencies of variants of the imidazolidine moiety of imidacloprid-related neonicotinoids and the relationship to partition coefficient and charge density on the pharmacophore

The pharmacophore of the neonicotinoid insecticide imidacloprid, nitroiminoimidazolidine, was modified to heterocycles such as thiazolidine, pyrrolidine, dihydroimidazole, dihydrothiazole, and pyridone conjugated to nitroimine (=NNO2) or nitromethylene (=CHNO2). Their 6-chloro-3-pyridylmethyl or 5-chloro-3-thiazolylmethyl derivatives were examined for insecticidal activity against the American cockroach by injection and for neuroblocking activity using the cockroach ganglion. Most of the compounds having the neonicotinoidal pharmacophore exhibited insecticidal activity at the nanomolar level, which was enhanced in the presence of synergists, and high neuroblocking activity at the micromolar level. Quantitative analysis for the compounds showed that the neuroblocking potency is proportional both to the Mulliken charge on the nitro oxygen atom and to the partition coefficient log P value. The equation for the insecticidal versus neuroblocking potencies indicated that both potencies are related proportionally with each other when the other factors are the same.     

Isolation and characterization of a novel immunomodulatory alpha-glucan-protein complex from the mycelium of Tricholoma matsutake in basidiomycetes

Tricholoma matsutake, a high-class edible mushroom in Japan, has been reported to have excellent biological activities, but difficulty in cultivating the fruit bodies and limited bulk availability have restricted detailed studies. We have developed a method of culturing in tanks, enabling the bulk supply of the mycelia. The preparation (CM6271) exerts modulative effects on the immune competence of mice and rats. In this study, a sodium hydroxide extract of CM6271 was defatted followed by fractionation with a combination of ion exchange chromatography and gel filtration in order to identify the components involved in the expression of the activity, and a single peak fraction (MPG-1) was obtained with reversed phase chromatography. MPG-1 was a glycoprotein (sugar:protein ratio, 94.3:5.7) with a relative molecular mass of 360 kDa, and the sugar moiety contained about 90% glucose. NMR spectra and methylation analysis revealed that the alpha-1,4-linkage was the predominant glucan linkage with alpha-1,6- and alpha-1,2-linkages in the minority. The amino acid composition in the protein moiety was rich in glutamine, alanine, asparagine, leucine, glycine, valine, serine, threonine, isoleucine, and proline. MPG-1 was resistant to degradation with amylase or protease. The oral administration of MPG-1 promoted, in a dose-dependent manner, the recovery of the mouse natural killer cell activity and serum IL-12 level that had been reduced by the loading of restraint stress. The dose of MPG-1 (25 mg/kg) required for the expression of the effect decreases to 1/12 of that of CM6271 (300 mg/kg). Furthermore, MPG-1 formed a complex with TGF-beta1 in vitro, modulating the biological activity of TGF-beta1 by binding to its active form. These results indicate that the mycelium of T. matsutake contains a novel alpha-glucan-protein complex with immunomodulatory activities.     

The status of atmospheric concentrations of ammonia in an intensive dairy farming area in central Japan

(pp. 41–46)
Silicon availability in 36 commercial nursery bed soils was evaluated by four methods the phosphate buffer (pH 6.2, 40 mmol L⁻¹), incubation, supernatant and acetate buffer (pH 4.0, 1 mol L⁻¹) Methods. The influence of silicon availability in the nursery bed soils on the silicon uptake of rice Oryza sativa L. cv. Hitomebore seedlings and the effect of silicon fertilizer application were examined in a glass house in 2002.
The results revealed that the best correlation between silicon content in rice seedlings and available silicon in soils was obtained with the phosphate buffer-solution method ( r  = 0.86). More precise evaluation of available silicon was achieved by grouping soils based on these phosphate absorption coefficients (PAC). The correlation coefficients between silicon content in rice seedlings and available silicon in soils were 0.92 and 0.72 for volcanic soils (PAC > 1500) and non volcanic soils (PAC < 1500), respectively.
We concluded that the phosphate buffer method is the most easily adjusted method for estimation of silicon availability in nursery bed soils, and silicon fertilizers should be applied when silicon availability in non-volcanic nursery bed soils goes below 200 mg kg⁻¹, whereas the level is less than 350 mg kg⁻¹ in volcanic soils.     

Uniquely stable 40 kDa subfragment-2 in carp myosin

Digestion of carp myofibrils at 30 degrees C in 0.5 M KCl medium with calcium ion generated unique 135 kDa heavy meromyosin (HMM). The HMM was not produced when digested at 10 degrees C. A further digestion of the 135 kD HMM isolated in the absence of calcium ion generated uniquely short subfragment-2 (S-2) with a size of 40 kDa (40 kDa S-2) together with subfragment-1 (S-1). The 40 kDa S-2 was identified by N- and C-end sequencing, and demonstrated to locate the amino end of the rod portion. The unfolding temperature for the 40 kDa S-2 was around 52 degrees C as studied by circular dichroism measurement. The same unfolding peak was also detected with the intact rod together with a large unfolding peak at around 36 degrees C coming from the rest of the rod portion, light meromyosin. The unfolding peak for the 40 kDa S-2 in myosin was a little lower (48 degrees C) than that in free form, suggesting the involvement of the head portion in the stability of the 40 kDa S-2 in the structure.     

Relationship between antibacterial activity of (+)-catechin derivatives and their interaction with a model membrane

(+)-Catechin derivatives with different alkyl chain lengths were synthesized from (+)-catechin and various straight chain alkylaldehydes in the presence of methyl mercaptan, and their antibacterial activities against Gram-positive bacteria were evaluated. The antibacterial activity increased markedly with elongation of the alkyl chain lengths of the derivatives and reached a maximum at a chain of four to seven carbons. Subsequently, interaction of the (+)-catechin derivatives with a model membrane using liposome was investigated. The derivatives with a chain of three carbons or more were found to have very strong affinity for the membrane. The injury action of the derivatives against the membrane was examined with liposome in which calcein was enclosed as a fluorescent indicator. The leakage was observed in the derivatives with chain lengths of four carbons or more. Particularly the derivatives with chains longer than five carbons are considered to destroy the liposome membrane judging from the degree of the fluorescent leakage. These results implied that the lipophilicity and disrupting ability of the (+)-catechin derivatives to the liposome membrane participate in their antibacterial activity.     

Oryzacystatin-II, a cystatin from rice (Oryza sativa L. japonica), is a dimeric protein: possible involvement of the interconversion between dimer and monomer in the regulation of the reactivity of oryzacystatin-II

We examined the biochemical and structural properties of oryzacystatin-II, a phytocystatin in rice (Oryza sativa L. japonica), under heat-stress conditions. The enzyme inhibitory reactivity of oryzacystatin-II was enhanced by heating in a temperature-dependent manner and reached a maximum level by heating at 65 degrees C for 10 min. Size-exclusion chromatography showed that oryzacystatin-II forms a homodimer at ambient temperature and that the enhancement of inhibitory reactivity is due to the conversion of the dimeric to a monomeric form. The monomeric form of oryzacystatin-II reverted to the dimer during storage at 4 degrees C, suggesting that dimerization is an intrinsic property of oryzacystatin-II. The affinity of the monomer for cysteine proteinases was significantly higher than that of the dimer. This is the first paper to describe the noncovalent dimerization for a cystatin under nonstress conditions.     

Development of an enzyme-linked immunosorbent assay to detect an immunomodulatory alpha-D-glucan-protein complex, MPG-1, in basidiomycete Tricholoma matsutake and related processed foods

We previously isolated a novel immunomodulatory alpha-(1,4)(1,6)(1,2)- d-glucan-protein complex (MPG-1) from mycelia of Tricholoma matsutake in basidiomycetes. In the present study, we raised a polyclonal antibody by immunizing rabbits with MPG-1 and constructed a sandwich enzyme-linked immunosorbent assay (ELISA) system to examine the distribution of MPG-1 among edible mushrooms and related processed foods. The system detected MPG-1 quantitatively at concentrations of more than 10 ng/mL, with a coefficient of variation of less than 10% by intra-assay and interassay precision. Analysis with the system of chemically modified MPG-1 suggested that the sugar moiety was mainly involved in the detection. The system detected MPG-1 in the extracts of the fruiting bodies of T. matsutake but not in those of 34 other basidiomycete species. Moreover, a significant amount of MPG-1 was detected in the extracts of their cultured mycelia. The antigenic structure of MPG-1 was relatively stable in terms of pH and temperature. MPG-1 was detected in processed foods supplemented with T. matsutake. These results suggest that MPG-1 is distributed predominantly in T. matsutake species and that the ELISA system can detect it in processed foods supplemented with T. matsutake.     

Surface-active properties of particle size fractions in two humic acids

The relationships between surface active properties and humic acid (HA) particle sizes were investigated. Two HAs from an Ando soil and a Brown forest soil were separated into 6 particle size fractions by gel permeation chromatography. Surface-active properties characterized by surface excess value (\gT mol cm^-2), cross-sectional surface area per molecule (A nm²), critical micelle concentration (CMC g L^-1), efficiency and effectiveness of water surface tension reduction were obtained by the measurement of the surface tension of HA solutions from different particle size fractions. For the HA from the Ando soil, except for the smallest particle size fraction, increasing particle size enhanced the efficiency of reduction of the water surface tension and decreased the CMC, while the effectiveness of reduction of the water surface tension was about the same. The surface activity of the HA from the Ando soil increased with increasing particle size. This phenomenon was similar to the surface activity of a homologous series of surfactants, which increased with increasing alkyl chain length. For the HA from the Brown forest soil, the smallest particle size fraction and three large fractions showed a high efficiency, namely a high surface activity. The smallest fraction from the Brown forest soil showed the highest efficiency and the lowest CMC value. In both HAs, the smallest particle size fraction showed exceptional surface-active properties compared with the other fractions and three fractions with large particle size showed a higher surface activity than other smaller fractions.