METABOLITE PROFILING OF SHOOT EXTRACTS,ROOT EXTRACTS,AND ROOT EXUDATES OF RICE PLANT UNDER PHOSPHORUS DEFICIENCY

We applied a metabolite profiling technique to investigate root exudates under phosphorus (P) deficiency. Oryza sativa was grown in culture solution containing three P levels (0, 1, and 8 mg P L^?1). Shoot extracts, root extracts, and root exudates were obtained from 18 and 23-day-old plants and their metabolites were determined by capillary electrophoresis/time-of-flight mass spectrometry. Eighty, 90, and 65 metabolites were identified in shoot extracts, root extracts, and root exudates, respectively. Sixty-three to eighty-four percent of the metabolites were exuded to the rhizosphere. More than 33% of the metabolites in the root exudates showed higher concentration at low P than at high P. On the other hand, only 14% of the metabolites in the root extracts showed lower concentration at low P than at high P. These results suggest that rice roots actively release many metabolites in response to P deficiency.     

Relative importance of protons and solution calcium concentration in phosphate rock dissolution by organic acids

A series of experiments was conducted to quantify the relative contribution of protons and other mechanisms to the dissolution of phosphate rocks (PRs) from six countries in solutions of low-molecular-weight-aliphatic organic acids. The amounts of P and Ca released after 3 d of incubation at 28°C were determined in all the experiments. In the first experiment the solubility of the PRs < 500 μm particle size) in 100 M (25 mL g^-1 PR) oxalic, tartaric, and citric acids was compared with that in three mineral acids and four chelating compounds. There were no differences in the amount of P released by the mineral acids, but the organic acids released more P than could be accounted for by protonation. The chelating compounds were the least effective. In the second experiment, 1 g each of Sri Lanka and Togo PRs was incubated with 2.5 mmol of the organic acids using three acid concentration (mM) : acid volume ratios (250:10, 100:25, and 25:100). The amount of P dissolved from the PRs and the amount of acid remaining in the filtrate were about the same for all three treatments. A mixture of the organic acids and the respective Na-salts was prepared at six different acid: salt ratios in the third experiment. Total acid concentration in all the solutions was 100 mM. Higher proportion of the Na-salt in the mixture decreased PR dissolution, while the amount of the acid remaining in the filtrate increased. The Ca concentration in the filtrate showed an opposite trend. The results indicated that PR dissolution by the organic acids was initially dependent on protonation, which accounted for only 13–38% of the amount of P dissolved. Most of the amount of P dissolved could therefore be attributed to other mechanisms. Removal of dissolved Ca from the solution appears to be the major factor controlling the subsequent dissolution of the PRs. The ability of tartaric and oxalic acids to dissolve effectively the PRs was attributed to the formation of an insoluble calcium compound which was precipitated from the solution. For the use of organic acids as a potential amendment for improving the P availability of PRs, the Ca binding power of the organic acids should also be considered.     

Historical aspects of soil classification in Japan

Historical perspective of soil classification in Japan from Max Fesca's soil classification in 1882 to the “Unified Soil Classification System of Japan (2002)” was outlined, aiming at reviewing the progress in soil classification. The evolution can be divided into the following five aspects: 1) Max Fesca's soil texture survey and soil classification from the agro-geological point of view under the influence of the German school; 2) Introduction of the concept of pedology into the classification under the influence of the Russian school led by Dokchaev; 3) Brief history of the classification of Andosols which has exerted a considerable influence on soil classification worldwide; 4) Soil classifications developed through the implementation of national soil survey projects to independently evaluate land suitability for the cultivation of paddy rice, upland crops, and for forest establishment; 5) Attempts to develop a comprehensive soil classification system in order to unify soil classification systems for the above-mentioned land uses from 1963 to the present.     

The membrane lipid bilayer as a regulated barrier to cope with detrimental ionic conditions: making new tolerant plant lines with altered membrane lipid bilayer

Several detrimental ionic conditions can occur in crop fields: soil acidity, salinity, heavy metal toxicity, and/or nutrient deficiency. Crop plants tolerant to these detrimental ionic conditions have excellent strategies that are related to external and/or internal mechanisms. Recently, we proposed a new concept of aluminum (Al) tolerance in plants; specifically, a plasma membrane (PM) lipid bilayer mechanism. This mechanism is defined as the retardation of Al permeation through the PM lipid bilayer based on the specific composition of the lipid molecules in the PM. The molecular basis of a less negatively charged PM lipid bilayer is smaller proportions of phospholipids and greater proportions of galactolipids and sterols. This leads to reduced adsorbability of detrimental ions onto the PM lipid bilayer, resulting in less permeabilization. Phenolics and carotenoids have two moieties; a hydrophilic moiety and a hydrophobic moiety. The hydrophobic moieties of these compounds can occlude the permeabilized spaces in the PM lipid bilayer, thereby reinforcing it. Another strategy to retard the permeability of the PM to detrimental ions is to decrease the proportion of stigmasterol, which has been shown to have no ability to reduce water permeability. The beneficial or harmful effects of various organic materials (organic fertilizers, soil organic matter, agrochemicals, or organic pollutants) on the productivity or quality of crop plants in relation to changes in the PM lipid bilayer are discussed. Modulation of the PM lipid bilayer is a promising strategy to produce new crop lines tolerant to detrimental ionic conditions.     

Neutral and acidic milk oligosaccharides of the striped skunk (Mephitidae: Mephitis mephitis)

The biological significance of the tremendous variation in proportions of oligosaccharides and lactose among mammalian milks is poorly understood. We investigated milk oligosaccharides of the striped skunk (Mephitis mephitis) and compared these results to other species of the clade Mustelida. Individual oligosaccharides were identified by proton nuclear magnetic resonance spectroscopy. In the striped skunk, six oligosaccharides were identified: isoglobotriose, 2′‐fucosyllactose, A‐tetrasaccharide, Galili pentasaccharide, 3′‐sialyllactose and monosialyl monogalactosyl lacto‐N‐neohexaose. Four of these have been found in related Mustelida and the other two in more distantly related carnivorans. The neutral and acidic oligosaccharides derive from three core structures: lactose (Gal(β1–4)Glc), lacto‐N‐neotetraose (Gal(β1–4)GlcNAc(β1–3)Gal(β1–4)Glc) and lacto‐N‐neohexaose (Gal(β1–4)GlcNAc(β1–3)[Gal(β1–4)GlcNAc(β1–6)]Gal(β1–4)Glc).     

Proposal of screening method for intestinal mucus adhesive lactobacilli using the enzymatic activity of glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH)

Adhesion tests are complex, time‐consuming and expensive, while the most important criterion for a probiotic lactobacilli is the ability to adhere to the human intestine. Thirty lactobacilli isolates from human intestinal tissues were measured for cell surface glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) activity using a microtiter plate screening method. GAPDH activities were detected in 21 out of 30 samples from 12 h cultures and in all samples from 18 h cultures. This suggests GAPDH is universally expressed on the bacterial cell surfaces from many lactobacilli. A statistically significant positive correlation was shown between GAPDH activity and adhesion using the BIACORE adhesion assay (P < 0.01). The new screening method using GAPDH enzymatic activity without an adhesion test may be possible due to the significant positive correlation of GAPDH activity with adhesion of lactobacilli derived from the human intestine.     

Molecular cloning and biochemical characterization of medaka (Oryzias latipes) lysosomal neu4 sialidase

Glycoconjugates are known to be involved in many physiological events in vertebrates. Sialidase is one of the glycosidases, which removes sialic acid from glycoconjugates. In mammals, the properties and physiological functions of sialidases have been investigated, while there is little understanding of fish sialidase. Here, to investigate the significance of fish neu4 sialidase, neu4 gene was cloned from medaka brain mRNA and identified. Sialidase-specific motifs (GPG, YRVP and Asp-Box) were well conserved in the medaka neu4 polypeptide. Optimal pH of medaka neu4 sialidase was 4.6, but its activity was sustained even at neutral and weak alkaline pH. The neu4 considerably cleaved sialic acid from 4-methylumbelliferyl-N-acetyl-α-d-neuraminic acid and sialyllactose, but not from ganglioside and fetuin, which are good substrates for human NEU4. neu4 activity was mostly detected in mitochondria/lysosome fraction after biochemical fractionation, and indirect immunofluorescence assays revealed neu4 localization in lysosome in neu4 overexpressed cells. Next, developmental change in medaka neu4 and other sialidase mRNA levels were estimated by real-time PCR. Each sialidases showed different expression patterns in embryonic development: neu4 was up-regulated at late developmental stage in embryo, and neu3a mRNA level was quite high in 0.5 dpf. On the other hand, neu3b expression was drastically increased after hatching, suggesting that each sialidase may play a different role in embryonic development.     

Purification and Characterization of Cathepsin B from the Muscle of Horse Mackerel Trachurus japonicus

An endogenous protease in fish muscle, cathepsin B, was partially purified and characterized from horse mackerel meat. On SDS-PAGE of the purified enzyme under reducing conditions, main protein bands were detected at 28 and 6 kDa and their respective N-terminal sequences showed high homology to heavy and light chains of cathepsin B from other species. This suggested that horse mackerel cathepsin B formed two-chain forms, similar to mammalian cathepsin Bs. Optimum pH and temperature of the enzyme were 5.0 and 50 °C, respectively. A partial cDNA encoding the amino acid sequence of 215 residues for horse mackerel cathepsin B was obtained by RT-PCR and cloned. The deduced amino acid sequence contains a part of light and heavy chains of cathepsin B. The active sites and an N-glycosylation site were conserved across species. We also confirmed that the modori phenomenon was avoided by CA-074, a specific inhibitor for cathepsin B. Therefore, our results suggest that natural cysteine protease inhibitor(s), such as oryzacystatin derived from rice, can apply to thermal-gel processing of horse mackerel to avoid the modori phenomenon. Meanwhile, this endogenous protease may be used for food processing, such as weaning meal and food for the elderly.     

Statistical Analysis of Metal Concentrations in a Sediment Core to Reveal Influences of Human Activities on Atmospheric Environment for 200 Years

Metal concentrations in a sediment core from a moat outside Osaka Castle in Japan were measured by ICP-MS following a microwave extraction method. Concentrations of metals in the sediment core samples peaked around 1945 when the World War II ended. This is in part due to great air raids on Osaka. In cluster analysis using metal concentrations, the fractions of sediment core samples were classified into two groups, representing natural sources (1795–1915) and anthropogenic sources (1922–1976), respectively. Results of lead isotope ratios also showed the anthropogenic influences from 1915 by changing the ratio values compared to those of natural sources. In addition, several components contributing to metal concentrations were identified by principal component analysis. The main component was controlled by natural sources and a decrease of the component score corresponded to an increased influence from anthropogenic sources. The largest impact of anthropogenic sources was shown around 1945.     

Reproduction of hydropericardium syndrome in three-week-old cyclophosphamide-treated specific-pathogen-free chickens by adenoviruses from inclusion body hepatitis

The pathogenicity of serotype 8 group I avian adenovirus (GIAAV) strains (TR630 and Saga97 strains) from inclusion body hepatitis (IBH) against cyclophosphamide (CY)-treated 3-wk-old specific-pathogen-free (SPF) chickens was examined. SPF chickens were inoculated intramuscularly with 10(7) plaque-forming units of viruses. Both strains from IBH could produce hydropericardium and mortality in CY-treated chickens as hydropericardium syndrome (HPS) that serotype 4 GIAAV strains cause, although they could not induce either hydropericardium or mortality in nontreated chickens. Histologically, hepatocytic necrosis with intranuclear inclusions, pancreatic acinar necrosis with intranuclear inclusions, and epicardial edema were seen in CY-treated chickens inoculated with GIAAV from IBH. Immunohistochemically, these inclusions were positive against GIAAV antigen. There were neither histologic lesions nor positive reactions against GIAAV antigen in nontreated chickens inoculated with GIAAV from IBH. From the present findings, pathogenic characteristics of IBH strains and HPS strains in the chickens were essentially the same.