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.     

Thermal adaptation of pacific bluefin tuna Thunnus orientalis to temperate waters

ABSTRACT:   Immature Pacific bluefin tuna Thunnus orientalis , tagged with archival tags, were released near Tsushima Island in the East China Sea during the winters of 1995 through 1998. Time-series data for ambient and peritoneal cavity temperatures, recorded every 128 or 256 s for 23 fish recovered, were analyzed. The objective of this study was to clarify the process of development of thermoconservation ability with growth in relation to adaptive mechanisms to cooler temperate waters. According to the results, mean ambient temperatures ranged from 14.9 to 20.7°C, which is almost within the optimum temperature range according to previous reports. Mean peritoneal temperatures were higher than ambient temperatures (19.7–27.3°C), but never reached 35°C, which would induce overheating. Although the mean thermal differences between peritoneal and ambient temperatures increased with body size, the rate of increase decreased with body size. A heat budget model suggests that as the insulation of the body develops, the estimated mean values of internal heat production decrease with body size. This is probably due to the allometric scale effect and explains why the thermal difference does not increase quickly with body size. It is likely that Pacific bluefin tuna inhabit cooler temperate waters in mid-latitude regions to avoid overheating.     

Diversity of S-RNase genes and S-haplotypes in Japanese plum (Prunus salicina Lindl.)

Summary

This report demonstrates the diversity of S-haplotypes in Japanese plum by molecular cloning of genomic DNAs and cDNAs that encode S-RNases. Nine different DNA fragments, designated as S^a–Sⁱ, were obtained from 17 Japanese plum cultivars by PCR with an S-RNase gene-specific primer set, Pru-C2 and PCE-R. Eleven different S-haplotypes were found in these cultivars. The banding patterns obtained with another S-RNase gene-specific primer set, Pru-T2 and PCE-R, corresponded to the S-haplotypes predicted from the Pru-C2 and PCE-R primer set. Several cultivars had the same S-haplotypes. Partial genomic DNAs for eight S-RNase genes and cDNAs for two S-RNases were cloned and sequenced. Deduced amino acid sequences contained conserved regions among the rosaceous S-RNases. Comparisons of the sequences from cDNAs and genomic DNAs revealed the presence of two introns in the S-RNase genes of Japanese plum as in other Prunus S-RNase genes. Pollination incompatibility groups and self-compatibility in Japanese plum were discussed with reference to the S-haplotypes.     

Correction to: Comparison of biomass estimates from multiple stratification approaches in a swept area method for Pacific saury Cololabis saira in the western North Pacific

Fisheries Science - A correction to this paper has been published: https://doi.org/10.1007/s12562-021-01506-9