Effect of Oxidizing Power of Roots on Iodine Uptake by Rice Plants

Although iodine is harmful to plants, rice plants ( Oryza sativa L.) absorbed iodine more selectively than bromine. To explain this selective absorption, the authors proposed the following hypothesis based on the fact that the standard redox potential for (I₂+ 2e = 2I⁻) is lower than that for (Br₂+ 2e = 2Br⁻) and (Fe³⁺+ e = Fe²⁺), and the roots of rice plants are able to oxidize ferrous ion (Fe²⁺) into ferric ion (Fe³⁺), namely rice plants oxidize iodide ion (I⁻) to form molecular iodine (I₂) via the oxidizing power of their roots, and absorb the molecular iodine formed more selectively than iodide ion. Bromine, by contrast, is absorbed by rice plants only in the form of ion (Br⁻). According to this hypothesis, there should be a significant correlation between the oxidizing power of the rice roots and the amount of iodine absorbed. Therefore, the relationship between the oxidizing power of the roots and the concentration of iodine absorbed was studied in a water culture using 8 varieties of rice plants. Rice seedlings, 14 d after germination, were cultured in a solution containing 1 mg L⁻¹ each of iodide and bromide ions for 3 d. The oxidizing power of the rice roots was evaluated based on the amount of 1-naphthylamine oxidized by the roots. A significant correlation (0.78, n = 16, 0.1% significant level) was found between the oxidizing power and the concentration of iodine absorbed by the roots. However, no relationship was found between the oxidizing power of the roots and the amount of bromine absorbed.     

Distribution of Lectin‐Bindings in the Testis of the Lesser Mouse Deer,Tragulus javanicus

The distribution of lectin bindings in the testis of the smallest ruminant, lesser mouse deer (Tragulus javanicus), was studied using 12 biotinylated lectins specific for d ‐galactose (peanut agglutinin PNA, Ricinus communis agglutinin RCA I), N‐acetyl‐d ‐galactosamine (Dolichos biflorus agglutinin DBA, Vicia villosa agglutinin VVA, Soybean agglutinin SBA), N‐acetyl‐d ‐glucosamine and sialic acid (wheat germ agglutinin WGA, s‐WGA), d ‐mannose and d ‐glucose (Lens culinaris agglutinin LCA, Pisum sativum agglutinin PSA, Concanavalin A Con A), l ‐fucose (Ulex europaeus agglutinin UEA I), and oligosaccharide (Phaseolus vulgaris agglutinin PHA‐E) sugar residues. In Golgi‐, cap‐, and acrosome‐phase spermatids, lectin‐bindings were found in the acrosome (PNA, RCA I, VVA, SBA, WGA and s‐WGA), and in the cytoplasm (PNA, RCA I, VVA, SBA, WGA, LCA, PSA, Con A and PHA‐E). s‐WGA binding was confined to the spermatid acrosome, but other lectins were also observed in spermatocytes. In spermatogonia, VVA, WGA, Con A, and PHA‐E bindings were observed. Sertoli cells were intensely stained with DBA and Con A, and weakly with PHA‐E. In interstitial Leydig cells, RCA I, DBA, VVA, Con A, PSA, LCA, WGA and PHA‐E were positive. UEA I was negative in all cell types including spermatogenic cells. Unusual distribution of lectin‐bindings noted in the testis of lesser mouse deer included the limited distribution of s‐WGA only in the spermatid acrosome, the distribution of DBA in Sertoli cells, Leydig cells and lamina propria, and the absence of UEA I in all type cells. The present results were discussed in comparison with those of other animals and their possible functional implications.     

A synthetic peptide from fibronectin inhibits experimental metastasis of murine melanoma cells

Adhesive interactions between cells and the extracellular matrix occur at several stages of metastasis. Such interactions might be inhibited by synthetic peptide probes derived from the cell-binding regions of matrix molecules. Gly-Arg-Gly-Asp-Ser (GRGDS) is a pentapeptide sequence that appears to be critical for cell interaction with fibronectin. Coinjection of GRGDS with B16-F10 murine melanoma cells dramatically inhibited the formation of lung colonies in C57BL/6 mice. Two closely related control peptides, in which specific amino acids within the GRGDS sequence were transposed or substituted, displayed little or no activity. Inhibition by GRGDS was dose-dependent, noncytotoxic, and did not result from an impairment of cellular tumorigenicity. GRGDS may function by inhibiting tumor cell retention in the lung since radiolabeled B16-F10 tumor cells injected with the peptide were lost at a substantially greater rate than control cells.     

Observation of d(x2-y2)-like superconducting gap in an electron-doped high-temperature superconductor

High-resolution angle-resolved photoemission spectroscopy of the electron-doped high-temperature superconductor Nd(2-x)Ce(x)CuO4 (x = 0.15, transition temperature T(c) = 22 K) has found the quasiparticle signature as well as the anisotropic d(x2-y2)-like superconducting gap. The spectral line shape at the superconducting state shows a strong anisotropic nature of the many-body interaction. The result suggests that the electron-hole symmetry is present in the high-temperature superconductors.     

Foliar absorption of nutrients: I

Recently, studies on foliar application have made splendid development in the field of agronomy and in the fertilizer industry. This fact has some important meanings. First, the conception of fertilizer has gradually changed from the original meaning. "Non-root" parts of plants do take up nutrients from spray and other applications. This conception could definitely be proved by the use of radioactive isotopes as the tracer. Many investigations by use of radioactive isotopes, ¹⁴C ( 1 and 2 ) ³²P (1, 3, 4, 5, 6, 7 and 8) ⁴²K (9 and 10) ⁴⁵Ca (10) etc. have since been conducted showing the foliar absorption of nutrients. The second important meaning is the improvement of applica tion methods of fertilizers. By the foliar application method, excellent effects which could not be carried out by the soil application method have been displayed. When fertilizers are applied to leaves of plants in critical times as a supplementary fertilizer, they can be absorbed quickly plentifully into plants. Foliar application of micronutrients, for instance, Mg, Fe, Zn, and Mn have been used succesfully to the deficiencies in plants. Among the macronutrients, phosphorus could perhaps offer more promise as a foliar applied fertilizer, because when phosphatic fertilizers are applied to soil, a large percentage of phosphorus usually becomes fixed in unavailable form to growing plants. On the other hand, especially in a high rainfall area, the application of soluble nitrogen fertilizer to the soil has resulted in low efficiency due to leaching loses (19). So, studies on foliar absorption of urea, phosphorus and micro-nutrients have especially been investigated by many workers. In other cases, there are possibilities that fertilizers can be applied to plants with germicides, insecticides, etc.     

Comparative studies on the photosynthesis of higher plants

1) CO₂ compensation points of the plants tested correlate well with the leaf anatomy. Low CO₂ compensation plants had well-developed VBS containing large and specialized chloroplasts but no plant with a high CO₂ compensation point possessed chloroplasts in the VBS.

2) CO₂ Compensation Points Closely Correlated With The Major Carboxylation Pathway In Photosynthesis. Low Compensation Plants Fixed CO₂ Via The C-4 Pathway (C-4 Plants) While High Compensation Plants Carried Out CO₂ Fixation By The Calvin Cycle (C-3 Plants).

3) Close correlations could be established for the CO₂ compensation point, the major carboxylation pathway, and glycolate oxidase activity. Glycolate oxidase activity was much higher in C-3 plants than in C-4 plants. On the other hand, dark respiration in C-4 plants was higher than that in C-3 plants.

4) TCA cycle activity in detached leaves was not inhibited to any large extent by illumination.

In C-3 plants, the release of ¹⁴CO₂ from alanine-1-¹⁴C increased with an increase in the ambient O₂ concentration; whereas, radioactivity in the sugar fraction was quite small at all O₂ concentrations. In C-4 plants the release of ¹⁴CO₂ was little affected by the ambient O₂ concentration while sugar formation was stimulated at high O₂ concentrations. This indicates that in C-3 plants CO₂ fixation is blocked at a high O₂ concentration, therefore, internal ¹⁴CO₂ is released from the leaf without being refixed, but in C-4 plants internal ¹⁴CO₂ can be efficiently refixed and metabolized to sugar by a combination of active PEP carboxylase and the ‘Kranz type’ of leaf anatomy.     

Crystalline silica minerals in air-borne pyroclastic materials

Quartz is the most abundant, essential constituent of common volcanic rocks whereas tridymite and cristobalite occur in siliceous volcanic rocks. The mineralogy these minerals has been well established (DEER et at., 1963).     

Improved method for easy and rapid determination of root length of vegetables

We developed an improved method for the determination of the root length of crisphead lettuce (Lactuca sativa L.) and Chinese cabbage (Brassica pekinensis Rupr.). Boiling of soil containing roots and stirring to collect the roots in water reduced the contamination with debris. The time required for removing the debris was shortened by 30% as compared to washing of roots with water. Boiling had no effect on the nitrogen concentration, but resulted in changes of the phosphate, potassium and calcium concentrations of roots. Use of a crosscounter plate shortened by 30% the time required for the line intersect method. The total time required for root length determination from a 1 kg soil sample was only 15.9 min.