Sadami Shibabe

Solubilization of endothelin receptors from bovine lung plasma membranes in a non-aggregated state and estimation of their minimal functional sizes

Bovine lung endothelin receptors were solubilized in a non-aggregated state and characterized in terms of their minimal functional size and chemical nature of the ligand-binding site. A variety of detergents and their combinations were tested for their efficiency to solubilize endothelin receptors from bovine lung plasma membranes, and a combination of 0.4% digitonin and 0.25% CHAPS was found to be very effective in obtaining highly dispersed receptor solution. Gel filtration of the CHAPS/digitonin-solubilized receptors revealed the presence of two receptor species eluting at the positions corresponding to 34 and 52 kDa. These values were in good agreement with those estimated by affinity labeling and SDS-polyacrylamide gel electrophoresis, establishing that they represent minimal functional units. Chemical modification of ligand-occupied and free receptors with p-chloromercuriphenylsulfonic acid revealed that both 34 and 52 kDa receptors have SH group(s) essential for the receptor activity in their ligand-binding sites.

Absorption and translocation of 59Fe and 14C-rhodotorulate in iron-stressed tomato.

Abstract Tomato plants, varieties FER and Earlygirl (both iron efficient), were grown under low Fe conditions for 9 days. Rhodotorulate ‐14C was isolated from Rhodotoruiate pilmanae cultured with 14C‐sucrose. The 14C‐ Rhodotorulate ‐Fe and Rhodotorulate‐ 59Fe were added to the Fe‐stressed plants for 6, 24 and 48 hour periods. It was evident from autoradiograms and tissue sampling that 59Fe and 14C were abundant in roots, stems and leaves. The 14C autoradiograms showed especially high density in the small younger leaves, as was found also with 59Fe. Unlike synthetic chelates rhodotorulate (or metabolized derivatives) were readily absorbed by the roots and translocated to the leaves.

イネ幼植物のカルシウム, ゲルマニウム, ルビジウムイオン吸収に対する重水の影響

Deuterium oxide affected all types of transport processes of ions in rice seedlings. The processes of the active transport of Rb+, the passive diffusion of Ca2+, and the preferential and specific absorption of Ge by the seedlings in D2O solutions, were suppressively distorted by D2O. The suppressive effect on the translocation of all ions studied and the absorption of Rb+, was greater with higher concentrations of D2O. However, clear-cut relations of the effect of increasing D2O concentrations on the ion transport were not obtained. The extent of the replacement of H2O by D2O in the plant appeared to affect the movement of ions in the plant.

Absorption of phosphate by rice seedlings in deuterium oxide

Abstract Growth of roots and shoots of rice seedlings was retarded by increasing concentrations of D2O. At 99.7% D2O the seedlings became pale yellow and withered within 48 hr. Phosphate absorption of the root of seedlings decreased proportionally with D2O concentration and translocation of absorbed anion by roots to shoots decreased markedly above 60% D2O. Water absorption of the seedlings was also depressed by D2O concentrations. D2O-inhibition curves for the absorption process drawn as relative rate vs D2O concentration on a semi-log scale exhibit no threshold in concentration of D2O.

The effect of different concentrations of deuterium oxide on rice seedling shoot and root tissue water

Abstract Deuterium oxide (D 2 O) depressed the absorption of water by rice seedlings. The concentration of D 2 O in root tissue water equilibrated immediately with the external solution at 87 and 78% of that of the external solution containing 0.98%-D 2 O and above 19%-D 2 O, respectively. Shoot tissue water increased sigmoidally, reaching a plateau after 5 hr, and the plateau value decreased from 61 to 45% of that of the external solution with an increase in D 2 O concentration of the external solution from 0.98 to 94%. The concentration of D 2 O in root tissue water of seedlings germinated in D 2 O solutions was similar to, but the concentration in shoot tissue water was not similar to that of the external solution. When the shoots excised from roots were left in air, both D 2 O concentration and water content of the shoots decreased with time. The concentration of D 2 O in tissue water of the shoots decreased slowly from shoot base to the base of the second leaf and steeply toward its apex. We concluded that (1) about 10% of the tissue water in whole seedlings is unexchangeable, and (2) the remaining 90% of tissue water is exchangeable with the external solution. The water translocated to leaves, howeber, is diluted rapidly with aerial H 2 O, and the amounts of water translocated to leaves and that diffused in them are balanced after 5–6 hr. This resulted in a 30% decrease of the deuterium (or tritium) concentration of shoot tissue water to about 60% of that of the external solution. The amount of the exchangeable water in the seedlings decreased with increasing D 2 O concentration of the external solution.

Effect of Storage on Microorganisms on Gamma Irradiated Rice

To observe the effect of 30°C storage on microorganisms on irradiated rice, unpolished and polished rice harvested in Japan were used as the samples. The storage life of polyethylene-packed rice containing 14-15% moisture was extended by 3-4 times by means of 0.2 Mrad irradiation. The number of molds on the irradiated rice grains was not increased for 3-4 months under this condition. When the moisture in the rice sample was 17%, more than 0.4 Mrad was necessary to extend its storage life.The species of molds which can propagate on storage-rice grains containing 17% moisture were mainly Aspergillus glaucus group and Penicillium citrinum series, where Asp. restrictus, Asp. vercicolor, Asp. candidus, etc. were minor ones. When moisture content was 16%, Asp. glaucus group and Asp. restrictus were observed. Only the halophilic species of Asp. restrictus was the species of molds which propagated on the rice sample containing 14-15% moisture.When a sheet of porous material, e.g. craft paper bag, was used to pack rice, the storage life of rice containing the moisture of less than 15% was extended by 3-4 times by means 0.2 Mrad irradiation, the storage conditions being 30°C 75% relative humidity. In this case the number of molds on rice was not increased for 3-4 months under this condition.