Prepartum maternal plasma glucose concentrations and placental glucose transporter mRNA expression in cows carrying somatic cell clone fetuses

In this study, the plasma glucose concentrations of cows carrying a somatic cell clone fetus during late pregnancy and placental glucose transporter (GLUT) mRNA levels at parturition were examined. Parturition was induced using dexamethasone, prostaglandin F(2α) and estriol in cows bearing a clone (Clone) or a fetus fertilized in vivo as a control (DEX). Plasma glucose concentrations were measured in the cows (days 257 and 271 of pregnancy and at parturition) and newborn calves. Cotyledon and caruncle tissues removed just after parturition were used for mRNA extraction. Expression of mRNA was also analyzed in control cows that were induced to undergo parturition without dexamethasone (PG) or that spontaneously delivered (SP). The glucose concentrations of the Clone group were significantly low at all points examined, but those of the calves were normal. The increase in the maternal glucose concentration from day 257 to parturition was significantly lower in the Clone group. Glucose concentrations were negatively correlated with birth weight for clones (day 257; r=-0.584, day 271; r=-0.286, parturition; r=-0.549). There was no difference in mRNA levels in the cotyledons among the animals examined. In the caruncles, the Clone and PG groups showed significantly higher GLUT1 and GLUT3 mRNA levels than the SP group, and the GLUT3 mRNA level was significantly higher in the Clone group than in the DEX group. The glucocorticoid receptor α mRNA level was significantly lower in the SP group than in the DEX group. Although spontaneous parturition and administration of dexamethasone suppressed the placental GLUT mRNA levels, the action was not observed in clone pregnancy. These results raise the possibility of facilitation of glucose transportation through the placenta to meet increased nutritional requirements of overgrown clone fetuses.     

Gross nitrification rates in four Japanese forest soils: heterotrophic versus autotrophic and the regulation factors for the nitrification

Measurements of gross NH ₄ ⁺ and NO ₃ ^? production in forest soils were conducted using the ¹⁵N pool dilution method. Mineral topsoils (0?C10?cm depth) were collected from four forests from northern to southern Japan with a natural climate gradient to elucidate the mechanisms regulating gross nitrification rates in forest soils. Additionally, we attempted to evaluate the relative importance of heterotrophic nitrification in gross total nitrification using acetylene as a specific inhibitor of autotrophic nitrification. Distinct differences were found among sites in the gross rates of NH ₄ ⁺ production (3.1?C11.4?mg?N?kg^?1?day^?1) and gross total nitrification (0.0?C6.1?mg?N?kg^?1?day^?1). The rates of gross heterotrophic nitrification were low in this study, indicating that heterotrophic nitrification is of minor importance in most forest mineral topsoils in Japan. Significant relations were found between gross autotrophic nitrification and gross NH ₄ ⁺ production, soil N, and soil C concentrations, but none was found between gross autotrophic nitrification and soil pH. We determined the critical value of the gross NH ₄ ⁺ production rates for gross autotrophic nitrification under which no gross autotrophic nitrification occurred, as well as the critical soil C/N ratio above which gross autotrophic nitrification ceased. Results show that tight coupling of production and consumption of NH ₄ ⁺ prevents autotrophic nitrifiers from utilizing NH ₄ ⁺ as long as NH ₄ ⁺ availability is low.     

The HSP terminator of Arabidopsis thaliana induces a high level of miraculin accumulation in transgenic tomatoes

High-level accumulation of the target recombinant protein is a significant issue in heterologous protein expression using transgenic plants. Miraculin, a taste-modifying protein, was accumulated in transgenic tomatoes using an expression cassette in which the miraculin gene was expressed by the cauliflower mosaic virus (CaMV) 35S promoter and the heat shock protein (HSP) terminator (MIR-HSP). The HSP terminator was derived from heat shock protein 18.2 in Arabidopsis thaliana . Using this HSP-containing cassette, the miraculin concentration in T0 transgenic tomato lines was 1.4-13.9% of the total soluble protein (TSP), and that in the T1 transgenic tomato line homozygous for the miraculin gene reached 17.1% of the TSP. The accumulation level of the target protein was comparable to levels observed with chloroplast transformation. The high-level accumulation of miraculin in T0 transgenic tomato lines achieved by the HSP terminator was maintained in the successive T1 generation, demonstrating the genetic stability of this accumulation system.     

Effect of sodium chloride stress on the plasma membrane ATPase of barley roots: Probable cause for decrease in ATPase activity

The regulation of plasma membrane ATPase activity by salt stress was investigated in barley roots. The plasma membrane fractions were prepared from the roots treated with or without 200 mM sodium chloride (NaCl) for one day. After salt treatment, ATPase activity reduced by 20 to 30% as compared with that of control roots. No significant changes in the content of total phospholipid and sterol were detected in the plasma membrane fraction by salt stress. After extraction of most of the phospholipids in the plasma membrane vesicles with a solution containing 1% (W/V) octylglucoside and 1% (W/V) Triton X‐100, the ATPase activity in salt‐stressed roots was lower than that of control roots. After reconstitution of detergent‐extracted protein into liposome, the reduction of ATPase activity by salt stress did not recover. Based on immunoblott analysis, the relative amount of H⁺‐ATPase in plasma membrane fraction prepared, from NaCl‐stressed roots was smaller than that of control roots. These results indicate that the reduction of H⁺‐ATPase activity by salt stress was caused by the decrease in the amount of H⁺‐ATPase rather than the modification of ATPase.     

Factors affecting immobilization and release of nitrogen in soil and chemical characteristics of the nitrogen newly immobilized IV. Chemical nature of the organic nitrogen becoming decomposable due to the drying of soil

This study deals with the effect of air-drying or oven-drying a soil and remoistening it on the flush of decomposition of soil organic nitrogen and with a comparison of the chemical nature of the nitrogen mineralized between the newly immobilized nitrogen in a soil receiving glucose and KNO₃ labelled with ¹⁵N and the native organic nitrogen in the soil.

Mineralization of soil organic nitrogen was remarkably accelerated through the effects of both air-drying and oven-drying, and the effect was much greater in the latter than in the former. The immobilized-N was made much more susceptible to mineralization than the native-organic N through the effect of air-drying or oven drying.

In the course of mineralization of the native-organic N, air-drying enhanced the decrease of amino acid N, in particular after 6-weeks incubation. Also, oven-drying intensified the decrease of all the forms of N for the same incubation periods; the decrease was most remarkable in the forms of amino acid N, unidentified N, and hydrolyzable ammonium N.

In the course of mineralization of the immobilized-N, air-drying heightened the decrease of unidentified N, in particular, and, to a slight degree, of amino acid N and hexosamine N after 6-weeks incubation. Oven-drying enhanced the decrease of all the forms of N for the same incubation period; the decrease was most remarkable in unidentified N. Hexosamine N also showed a substantially high susceptibility to mineralization through the effect of oven-drying the soil.

From these results it is certain that the principal organic nitrogen compounds becoming decomposable through the drying effect belong to the peptide complex substances.     

Some regulative properties of glutamine synthetase in cucumber leaves

Glutamine synthetase (L-glutamate: ammonia ligase (ADP) EC 6. 3. t 2) was prepared from cucumber leaves grown on ammonium medium and some regulative properties were investigated. The apparent Michaelis constant (Km) values of the various substrates and cofactors were determined. Lineweaver-Burk plots gave a Km of 4.5mM with L-glutamate, 0.74mM with ATP and 3.1 mM with NH₂OH. Metals, including Cu²⁺, Hg²⁺, Zn²⁺, Ni²⁺, Fe²⁺, and Fe³⁺, strongly inhibited the enzyme activity, Cd²⁺ did not inhibit the enzyme activity markedly, in contrast with its effect on the rice enzyme. Ca²⁺ was quite inhibitive to enzyme reaction and more than 50% of the activity was lost at 3 mM. The amino acids tested generally had no effect on the enzyme activity except alanine, which showed little but clear inhibition. Isocitrate and α-ketoglutarate were slightly promotive to enzyme activity while pyruvate and glyoxylate (24 mM) significantly inhibited the enzyme activity. Glucose-l- or -6-phosphate and fructose-6-phosphate were inhibitive to similar degrees, about 20% at 22.5 mM, and 3-phosphoglycerate (22.5 mM) markedly inhibited the enzyme activity up to 56%. Among the nucleotides tested, UTP, CTP, and GTP inhibited slightly, and marked inhibitions of H and 78% were observed after the addition of AMP (5 mM) and ADP (5 mM) respectively. Pyridoxal-5′-phosphate, which is a characteristic incompetitive inhibitor of L-glutamate and NH₂-OH, here inhibited enzyme activity significantly. On the other hand, pyridoxamine-5′-phosphate had almost no effect. The inhibition caused by the former was not recovered by the latter. This response of glutamine synthetase to both compounds was in agreement with the idea that the nitrogen status of the plant could be reflected by the ratio pyridoxamine phosphate/pyridoxal phosphate. Also this suggested that the regulative properties of glutamine synthetase with respect to pyridoxal or pyridoxamine phosphate could be understood from the point of view of the economical use of nitrogen.     

Enhancement of callose production by a combination of aluminum and iron in suspension-cultured tobacco (Nicotiana tabacum) cells

In nutrient medium, aluminum (A1) enhances ferrous ion [Fe(II)] -mediated per oxidation of lipids, which results in the loss of the plasma membrane integrity and the accumulation of A1 in tobacco cells. Under these conditions, the mechanism of callose production and possible involvement of callose in the accumulation of Al were investigated. Callose production was enhanced by both Al and Fe(II), but not by A1 or Fe(II) alone, and the enhancement was inhibited by a lipophilic antioxidant, suggesting that the enhancement of callose production is caused by the A1-enhanced, Fe(II)-mediated peroxidation of lipids. The enhancement of callose production depended on the presence of external Ca²⁺ in the treatment medium. The activity of β-l,3-glucan synthase in the microsomes was increased several times by the addition of Ca²⁺ in the assay medium, although the activity in the microsomes was reduced by the treatment of cells with Al and Fe(II) together. Therefore, it is likely that callose production is enhanced by exogenous Ca²⁺ via the AI-enhanced, Fe(II)-mediated peroxidation of lipids. During the exposure of the cells to Al and Fe(II), callose production started and increased simultaneously with Al accumulation. However, the digestion of callose in the cell wall materials prepared from the A1-treated cells by laminarinase did not release A1, suggesting that callose is not involved in the binding or trapping of A1.     

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.     

Subsoil water available in suction and poor in amount under continuous grassland use

Soil water storage in grassland is critical to regulate herbage yield while it may be threatened by continuous land use without plowing because of the progress of soil compaction associated with worsening soil hydraulic properties. This study aimed at contrasting the quantity and the availability of soil water in a meadow which had not been renovated for 13 years. We monitored matric potentials and mass soil water contents to 100 cm depth from autumn to winter in which plant transpiration was dormant. Soil water capacities were determined with soil water characteristics. The measurements were made in both a harvesting area in which agricultural vehicles had been operated, and a tree cover area which had experienced almost no vehicle loads. The soil layer in the tree cover area had a larger capacity for readily available moisture than that in the harvesting area. The matric potentials in the tree cover area varied in time between 0 and -1000 cm regardless of depth while those in the harvesting area were rather steady. These suggested better pore water continuity in the tree cover area. In the subsoil layers in both the harvesting and the tree cover areas, the soil water contents in terms of actually stored water did not reach as high a level as those expected from the soil moisture characteristics of the matric potential of -1000 cm. On the other hand, the measured matric potentials were consistently readily available for plants during the entire period of measurement. The apparent discrepancy between the matric potentials in readily available vs. actually stored water implied that the subsoil layers had become drier than observed during the study period, and that soil water hysteresis had prevented the full recovery of the water storage.