Effect of biotite,zeolite, heavy clay,bentonite and apatite on the uptake of radiocesium by grass from peat soil

Biotite is a potassium rich mineral, which is used as a fertilizer in organic farming and as a soil amendment in conventional farming. Its ability to reduce ¹³⁴Cs uptake by ryegrass from peat soil was studied in pot experiments and compared with zeolite, heavy clay, bentonite and apatite. In addition, the long-term effect of biotite on ¹³⁷Cs uptake from peat soil was studied in the peat field. In the pot experiments in the first cut of ryegrass, the minerals decreased ¹³⁴Cs uptake by plants in the following order: zeolite > heavy clay > bentonite > biotite > apatite. Apatite did not have any effect on the plant ¹³⁴Cs level. In the later cuts, the uptake of ¹³⁴Cs from biotite-treated soil decreased further while that from soils treated with other minerals remained unchanged or even increased. In general, ¹³⁴Cs uptake by plants decreased with increasing mineral level. The decrease of ¹³⁴Cs uptake became more efficient, especially at the early growth stage, by mixing small amounts of zeolite in biotite. The results of the field experiment indicated the long-term effect of biotite on reducing ¹³⁴Cs uptake by plants. Biotite application rate was 30 t ha-1. The five-year mean of the plant/soil concentration ratio of ¹³⁷Cs was 0.05 for biotite-treated soil, in contrast to 0.14 for the control soil. On the whole, biotite reduced considerably the ¹³⁷Cs level of plants on peat soil and this effect was long-lasting. For an effective reduction of plant radiocesium a great quantity of biotite is needed and therefore it is most suitable for greenhouse cultivation where contaminated slightly decomposed peat is used as a growing medium.     

Root respiratory quotient and nitrate uptake in hydroponically grown non-mycorrhizal and mycorrhizal wheat

 Oxygen and CO₂ fluxes were measured in hydroponically grown mycorrhizal and non-mycorrhizal Triticum aestivum L. cv. Hano roots. The NO₃ ^– uptake of the plants was used to estimate the amount of root respiration attributable to ion uptake. Plants were grown at 4 mM N and 10 μM P, where a total and viable mycorrhizal root colonisation of 48% and 18%, respectively, by Glomus mosseae (Nicol. and Gerd.) Gerd. and Trappe (BEG 107) was observed. The O₂ consumption and NO₃ ^– uptake rates were similar and the CO₂ release was higher in mycorrhizal than in non-mycorrhizal wheat. This resulted in a significantly higher respiratory quotient (RQ, mol CO₂ mol^–1 O₂) in mycorrhizal (1.27±0.13) than in non-mycorrhizal (0.79±0.05) wheat. As the biomass and N and P concentrations in mycorrhizal and non-mycorrhizal wheat were the same, the higher RQ resulted from the mycorrhizal colonisation and not differences in nutrition per se. Accepted: 26 March 1999     

Comparison of two test systems for measuring plant phosphorus uptake via arbuscular mycorrhizal fungi

 Plant phosphorus uptake via external hyphae of arbuscular mycorrhizal fungi has been measured using compartmented systems where a hyphal compartment is separated from a rooting compartment by a fine mesh. By labelling the soil within the hyphal compartment with a radioactive phosphorus (P) isotope, hyphal uptake of P into the plant can be traced. The objective of this growth chamber study was to test two hyphal compartments of different design with respect to their suitabilities for measurement of hyphal P uptake. One hyphal compartment was simply a nylon mesh bag filled with ³²P-labelled soil. The labelled soil in the other hyphal compartment was completely surrounded by an 8–10 mm layer of unlabelled soil that served as a buffer zone. Mycorrhizal and non-mycorrhizal subterranean clover plants were grown in pots with a centrally positioned hyphal compartment. Uptake of radioactive P by non-mycorrhizal control plants was 25% of that by mycorrhizal plants with the mesh bag but only 3% when including the buffer zone. Based on this good control of non-mycorrhizal P uptake from within the hyphal compartment and its greater ease of handling once produced, we judged the hyphal compartment including a buffer zone to be superior to the mesh bag. Accepted: 15 September 1998     

Intestinal absorption of copper from drinking water containing fulvic acids and an infant formula mixture studied in a suckling rat model

The purpose of this study was to investigate if the intestinal absorption of copper in drinking water is altered in the presence of complexing agents from a fulvic acid mixture and an infant formula powder. Ten to twelve day old rat pups were given a single oral dose of radio-labeled Cu in deionized water (0.93 mg Cu/l), in water containing fulvic acids (10 mg/l), in infant formula mixed with deionized water, or in infant formula mixed with water containing fulvic acids. Six hours after dosage, radioactive Cu was analyzed in the mucosa of the small intestine, the liver and the remaining carcass (excluding the liver and gastrointestinal tract) by gamma counting. Dialysis and centrifugation experiments showed that Cu was complexed by components in the fulvic acid and formula mixtures, although the presence of fulvic acids in the water did not alter the Cu fractionation in the formula. The fractional Cu uptake (% of dose) from the intestinal lumen to the mucosa was not markedly changed by the presence of the chelating agents. However, the retention of Cu in the intestinal mucosa was increased by both fulvic acids and formula. Concomitantly, the absorption rate of Cd to the circulatory system was decreased. No interactive effect between fulvic acids and formula was found on the Cu absorption. These findings indicate that the water quality may be an important determinant of the rate of intestinal Cu absorption from drinking water. Moreover, in the future risk assessment of copper in drinking water, the possibility of alterations in absorption of drinking-water Cu has to be considered when the drinking water is used for cooking.     

Uptake of reconstituted Na,K-ATPase vesicles by isolated lymphocytes measured by FACS, confocal microscopy and spectrofluorometry

Na,K-ATPase (EC, 3.6.1.37, Na,K-ATPase) is a fundamental vital membrane transport and receptor system which, after biosynthesis, is exported to the plasma membrane in inside-out vesicles. Na,K-ATPase can be extracted form the natural membrane and inserted into artificially formed phosphatidylcholine vesicles (liposomes). The ultrastructure of the reconstituted vesicles has been fully described. In the present work, the Na,K-ATPase-vesicles were labeled with fluorescent tracers either in their water or membrane phase, incubated with freshly isolated human lymphocytes, and the resulting cellular fluorescence measured with fluorescence activated cell sorting (FACS), confocal microscopy and spectrofluorometry. The FACS data show that all lymphocytes take up Na,K-ATPase-vesicles in a dose-and temperature-dependent fashion. Three-dimensional analysis of the fluorescence by confocal microscopy reveals that the fluorescence is contained within the cells. Quantitative determination by spectrofluorometry indicates that depending on the vesicle/cell ratio, a single lymphocyte takes up 650 to 36,500 vesicles within 30 min at 37°C together with up to about 200,000 renal Na,K-ATPase molecules.     

Potassium Translocation into the Root Xylem

Abstract: Potassium is the most abundant cation in cells of higher plants and plays vital roles in plant growth and develop ment. Since the soil is the only source of potassium, plant roots are well adapted to exploit the soil for potassium and supply it to the leaves. Transport across the root can be divided into three stages: uptake into the root symplast, transport across the symplast and release into the xylem. Uptake kinetics of potassium have been studied extensively in the past and sug gested the presence of high and low affinity systems. Molecular and electrophysiological techniques have now confirmed the existence of discrete transporters encoded by a number of genes. Surprisingly, detailed characterisation of the transpor ters using reverse genetics and heterologous expression shows that a number of the transporters (AKT and AtKUP family) func tion both in the low (μM) and high (mM) K⁺ range. Electrophy siological studies indicate that K⁺ uptake by roots is coupled to H⁺, to drive uptake from micromolar K⁺. However, thus far only Na⁺ coupled K⁺ transport has been demonstrated (HKT1). Ion channels play a major role in the exchange of potassium be tween the symplast and the xylem. An outward rectifying chan nel (KORC) mediates potassium release. Cloning of the gene en coding this channel (SKOR) shows that it belongs to the Shaker super-family. Both electrophysiological and genetic studies demonstrate that K⁺ release through this channel is controlled by the stress hormone abscisic acid. Interestingly, xylem par enchyma cells of young barley roots also contain a number of in ward rectifying K⁺ channels that are controlled by G-proteins. The involvement of G-proteins emphasises once more that po tassium transport at the symplast/xylem boundary is under hor monal control. The role of the electrical potential difference across the symplastxylem boundary in controlling potassium release is discussed.     

Cd/Fe Interaction in Higher Plants - Its Consequences for the Photosynthetic Apparatus

Cadmium is one of the most dangerous environmental pollutants, affecting, among other things, plant mineral composition. It easily interacts with iron, one of the most important elements for plant growth and metabolism. This interaction, including modifying effects of lowered or excessive Fe supply on Cd-exposed plants and its consequences for the photosynthetic apparatus is reviewed. The influence of modified Fe and Cd supply on the uptake of both metals, their distribution, plant growth, and photosynthesis is also explained. Moderate Fe excess has a beneficial influence on Cd-treated plants, resulting in more intensive growth, photosynthetic pigments accumulation, and more efficient light phase of photosynthesis. Nutrient-medium Fe deficiency increases plant susceptibility to Cd. The main open questions of Cd/Fe interaction are: (1) the strong Fe-dependency of Cd mobility within the plant, and (2) photosynthetic dark phase adaptation to Cd stress. This revised version was published online in June 2006 with corrections to the Cover Date.     

Diurnal variations in ventilatory and cardiorespiratory responses to submaximal treadmill exercise in females

Diurnal variations in ventilatory and cardiorespiratory responses to submaximal treadmill exercise were analysed in 11 eumenorrhoeic women and in 10 women using monophasic oral contraceptives. Subjects performed submaximal treadmill exercise at three intensities averaging 7, 8, and 9 km x h(-1), each for 4 min at 0800, 1300 and 1700 hours, assigned randomly on 3 separate days. Rectal temperature was measured before (T(rec(b))) and after (T(rec(a))) exercise. Cardiac frequency (f(c)), ventilation (V(E)), oxygen uptake (VO(2)), carbon dioxide output (VCO(2)), and respiratory exchange ratio (R) were assessed in the last minute of each stage of the exercise. Both T(rec(b)) and T(rec(a)) increased from 0800 to 1700 hours (P < 0.001). For a given submaximal work rate, VO(2) and VCO(2) were higher in the afternoon compared to the morning. Similarly, R was increased at 1700 hours compared to 0800 hours during the recovery period following exercise (P < 0.05). However, V(E) did not vary significantly during the day at any of the running intensities. No significant interactions (group x time of day) were observed in any of the studied parameters. In contrast to ventilation, the VO(2) and VCO(2) of the females during submaximal exercise were both affected by the time of day, without any differences between eumenorrhoeic women and users of oral contraceptives.     

Cd2+、Al3+作用下蚕豆UDS与微核相关性分析及高等植物UDS技术初探

为探讨金属离子对高等植物非按期DNA合成(UnscheduledDNASythesis,简称UDS)和微核(MCN)的诱导作用、二者之间的关联性以及利用高等植物UDS技术检测环境诱变物的可行性,利用3HTdR前体掺入法研究了Cd²⁺、Al³⁺作用下蚕豆的UDS效应。结果表明,Cd²⁺、Al³⁺均能不同程度地诱导蚕豆UDS和MCN的发生;UDS量与微核率(MCNF)之间呈负相关(r<0),但相关不显着(|r|0.05),且二者间的相关程度在Cd²⁺和Al³⁺两种金属离子作用下没有显着差别(P>0.05);利用高等植物UDS技术检测环境诱变物质,在一定受检物剂量范围内是可靠的,但超过这个剂量范围,UDS技术无法检出.     

Cu~(2+)、Pb~(2+)和Cd~(2+)对荞麦种子中抗氧化酶活性的影响

近年来,有关荞麦降血脂、降血糖和抗衰老等的作用引起国内外生化、营养和医药学界的普遍关注[1,2].一些研究表明,荞麦中富含超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和谷胱甘肽过氧化物酶(GSH-Px)等能够清除机体内超氧阴离子自由基(O-·2)、羟自由基(·OH)和H2O2等有害物质?..