Search

The Anqing section of the Yangtze (Changjiang) River in Anhui Province, China, is one of the most important migratory routes and distribution of the highly valued diadromous estuarine tapertail anchovy Coilia nasus. In the past, this section has suffered a severe loss of C. nasus resources caused by human activities, especially overfishing and water pollution. Since 2019, a fishing ban policy for the species in the Yangtze River has been introduced in China for resource restoration. Otoliths are calcium carbonate structures, and otolith microchemistry can provide detailed life history information that can be used to compare habitat use between different saline water bodies. To study the habitat history of C. nasus in the Anqing section of the Yangtze River after the implementation of the fishing ban, we examined the microchemical characteristics (Sr and Ca) of otoliths from the long (previously named C. ectenes) and short maxillary (previously named C. brachygnathus) types of anchovy using electron probe X-ray microanalysis (EPMA). Line-transect analysis of Sr/Ca ratios suggested that the short maxillary type of C. nasus could be divided into two groups. The otolith Sr/Ca ratios (calculated and expressed as Sr/Ca ×1, 000) of one group were always < 3.0, indicating their freshwater residency. Those of the other group had phases of low (< 3.0, believed to be indicative of a freshwater habitat) and high values (> 3.0, believed to be indicative of a brackish or seawater habitat), indicating that anchovies not only have a freshwater habitat history with low salinity but also a brackish habitat history with high salinity. The latter group of anchovies were typically anadromous C. nasus, as the Sr/Ca ratio of the otoliths of C. nasus fluctuated significantly and coincided with variations between freshwater and estuarine brackish or seawater (i.e., anchovies experienced not only freshwater habitats but also brackish water habitats at different stages of their life history). The Sr content mapping of EPMA with different color patterns for freshwater (blue), brackish water (green-yellow) and seawater (red) habitats also confirmed the results obtained from the line-transect analysis. Our results demonstrated that the population composition of C. nasus in the Anqing section of the Yangtze river became complex, and there was coexistence of freshwater resident and anadromous C. nasus in the Anqing section of the Yangtze River in Anhui Province, China (i.e., freshwater resident and anadromous short maxillary and anadromous long maxillary type C. nasus). This phenomenon may suggest a restoration of C. nasus resource diversity after the implementation of the fishing ban in the Anqing section of the Yangtze River.

Rare, heterogeneously composed platinum group element alloy micronuggets (PGNs) occur in primitive meteorites, micrometeorites, and terrestrial impactite deposits. To gain insight into the nature of these phases, we developed a workflow for the characterization of PGNs using modern scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry at a low accelerating voltage of 6 kV. Automated feature analysis-a combination of morphological image analysis and elemental analysis with stage control-allowed us to detect PGNs down to 200 nm over a relatively large analysis area of 53 mm2 with a conventional silicon drift detector (SDD). Hyperspectral imaging with a high-sensitivity, annular SDD can be performed at low beam current (∼100 pA) which improves the SEM image resolution and minimizes hydrocarbon contamination. The severe overlapping peaks of the platinum group element L and M line families at 2-3 keV and the Fe and Ni L line families at <1 keV can be resolved by peak deconvolution. Quantitative elemental analysis can be performed at a spatial resolution of <80 nm; however, the results are affected by background subtraction errors for the Fe L line family. Furthermore, the inaccuracy of the matrix correction coefficients may influence standards-based quantification with pure element reference samples., Competing Interests: Conflict of Interest The authors declare that they have no competing interest., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Microscopy Society of America.)

The aim of the study is to characterize the size-resolved urban haze particles and investigate their modification in morphology and composition in summer and winter using the semi-quantitative electron probe X-ray microanalysis (EPMA) based on both scanning and transmission electron microscopies equipped with ultrathin-window energy dispersive X-ray spectrometers (SEM-EDX and TEM-EDX). The haze and non-haze particles were collected through a seven-stage May cascade impactor on Dec. 29-30, 2009 and Jan. 8-9 and July 11-14, 2010 in Taiyuan, a typical inland city in the North China Plain. Approximately 3752 atmospheric particles in the size ranges of 4-2 μm, 2-1 μm, 1-0.5 μm, and 0.5-0.25 μm in aerodynamic diameter were measured and identified according to their secondary electron or TEM images and elemental atomic concentrations calculated through a Monte Carlo simulation program. Results show that on the haze days many reacted or aged mineral dust particles were encountered, in which the sulfate-containing ones outnumbered the nitrate-containing ones in the winter samples while it was on the contrary in the summer samples, suggesting different haze formation and evolution mechanisms in summer and winter. Furthermore, in the haze events (especially in summer), many CNOS-rich particles, likely mixtures of water-soluble organic carbon with (NH4)2SO4 or NH4HSO4, were observed not only in the submicron but also in the super-micron fractions. The simultaneous observation of the fresh and aged CNOS-rich particles in the same SEM or TEM images implied that the status and components of secondary particles were complicated and changeable. The significant increase of both elemental concentration ratios of [N]/[S] and [C]/[S] in the aged ones compared to the fresh ones indicated that NH4NO3 and secondary organic matter were likely absorbed onto (NH4)2SO4 or NH4HSO4 particles and mixed with them. K-rich, Fe-rich, and heavy metal-containing particles in TEM-EDX measurement were detected more in the winter haze samples than in the summer ones, suggesting that they tend to be smaller in size and mainly derive from anthropogenic biomass burning and coal combustion. It was concluded that the combined use of SEM-EDX and TEM-EDX can identify both submicron and super-micron urban haze particles in a straightforward way and trace their modifications in size, shape, mixing state, and chemical compositions in different seasons, helping address their evolution processes and hazards on human health. [ABSTRACT FROM AUTHOR]

To clarify the contribution of Ca to the gravitropic response, quantitative X-ray microanalyses were performed on cryosections of roots of soybean seedlings reoriented horizontally from their original vertical orientation. After reorientation, the roots bent gradually toward the ground at the elongation zone. The concentrations of Ca in the cell walls, cytoplasmic matrices and central vacuoles of cortical cells were measured in the upper and lower halves of the elongation zone at 0, 30, 60 and 120 min after reorientation. The Ca concentration did not significantly change in the cytoplasmic matrices or vacuoles. Additionally, the Ca concentration did not change significantly in cell walls at 30 min after reorientation; however, beyond 30 min, this concentration significantly increased gradually in the lower half of the elongation zone and decreased in the upper half of the elongation zone, indicating a typical asymmetrical distribution of Ca. These results suggest that Ca moves apoplastically in soybean roots to produce an asymmetrical Ca distribution in the elongation zone, which contributes to root curvature. The possible role of Ca in accelerating or repressing the effect of auxin is also discussed in this study. [ABSTRACT FROM AUTHOR]

An accuracy of elemental composition of submicron PZT films was investigated using nondestructive method of the electron probe X-ray microanalysis based on energy dispersive analyzer. PZT films RF-magnetron sputtered on Pt/SiO2/Si substrate were annealed to create the perovskite phase in the temperature range of 530-570°C. Unusual changes of lead content at elevated annealing temperatures were observed. The variation of incident angle of probing electrons was used to evaluate qualitatively lead excess on the film depth. Mechanisms of perovskite phase formation in the films are discussed. [ABSTRACT FROM PUBLISHER]

The applicability of laser ablation (LA) inductively coupled plasma (ICP) spectrometry for assessing elemental distributions in layered ceramics was investigated and compared with electron probe microanalysis (EPMA). Ordinary glazed wall tiles were employed as model specimens due to their defined structure and composition. They were used for calibration in the analysis of ancient pottery. A qualitative depth profile was acquired by single-spot laser drilling perpendicular to coatings with a Nd:YAG (1064 nm) laser coupled with an ICP optical emission spectrometer (OES). The lower lateral resolution associated with the laser spot diameter of 1.0 mm led to smoothing of the depth profile due to the averaging of local irregularities. In addition, transverse line scans by ablation across the tile section using an ArF* (193 nm) laser coupled with an ICP mass spectrometer (MS) were performed. LA-ICP-OES depth profiles and LA-ICP-MS transverse scans were validated by EPMA section scans and 2D back-scattered electrons images. The LA-ICP-OES acquisition was less dependent on sample surface and layer irregularities, whereas the transverse line scan over the tile section with the small-spot beam offered insight into the micromorphology of the individual layer. The combined approach revealed the occurrence of individual mineral grains, micro-heterogeneities and the character of interfaces between layers. [ABSTRACT FROM AUTHOR]

Abstract: Nine coppery alloys and five basaltic glasses have been quantitatively evaluated as the reference materials to employ in electron probe X-ray microanalysis. The optimum conditions for measurements were selected considering the dependence of intensity and detection limit on the conditions of the X-ray radiation excitation and analytical signal recording. The homogeneity of basaltic glasses and coppery alloys has been examined. The dependence of electron probe X-ray microanalysis accuracy on the homogeneity of reference materials was studied in the reference materials of coppery alloys. Six data sets comprising the average concentrations, standard deviations, relative standard deviations, confidence interval and the z-score of data quality were calculated for 50 control samples: 10 alloys, 14 glasses, 2 metals, 24 minerals and oxides. The average compositions of every control sample were derived in 8–16 analyses. The measured values were corrected for matrix effects applying the original program. These series of concentrations have been compared with each other and with the certified/recommended values using 2-pair selective Student''s t-test. The results gained from both laboratory reference materials and certified glass reference materials show comparable accuracy. The quality of all available results complies with the “applied geochemistry” category of performance (2nd category). The laboratory reference materials give comparable accuracy to certified reference materials and can be used for calibrating microprobe techniques, as well as data quality control. The application of laboratory reference materials in microanalysis of silicate minerals and coppery alloys allows reliable analytical data to be acquired. The applications in mineralogy and metallurgy can be extended successfully to the targets when certified reference materials are not available. [Copyright &y& Elsevier]

Low-Z particle electron probe X-ray microanalysis, a single-particle analysis method, was used to characterize aerosol samples collected in Chuncheon, Korea, before and during a dust storm that occurred between 10 and 12 March, 2004. Four different samples were analyzed: just before the storm, peak time of the storm, late stage of the storm, and end of the storm. All four of the samples were found to have experienced chemical modifications during long-range transport due to elevated levels of nitrate and sulfate that resulted from atmospheric reactions with CaCO3 and sea-salt particles. The sample collected just before the storm underwent the most extensive chemical modification during transport. For this particular sample, the overall relative abundances of reacted CaCO3 and sea-salt particles were 9.8% and 44.2%, respectively. The sample collected at the peak time of the storm also experienced extensive chemical modification with overall relative abundances of reacted CaCO3 and sea-salt particles at 4.3% and 23.3%, respectively. The backward trajectory analysis for this particular sample revealed two different types of air-masses arriving at the sampling site in Korea; one is high-altitude air-masses moving rapidly and carrying Asian dust particles and the other a slow-moving low-altitude air-mass from eastern China coastal areas. The single-particle characterization of this same sample showed that the Asian dust particles were mixed with sea-salts entrained over the Yellow Sea, as well as air pollutants from the eastern China coastal areas. However, as the Asian dust storm continued, soil-derived mineral particles became dominant in the samples that were collected at the late stage of the storm and at the end. For this specific Asian dust storm, the mixing of sea-salts and pollution with Asian dust particles was observed to occur just at the early stage of the storm. [Copyright &y& Elsevier]

Abstract: In order to clearly elucidate whether Asian Dust particles experience chemical modification during long-range transport, it is necessary to characterize soil particles where Asian Dust particles originate. If chemical compositions of source soil particles are well characterized, then chemical compositions of Asian Dust particles collected outside source regions can be compared with those of source soil particles in order to find out the occurrence of chemical modification. Asian Dust particles are chemically and morphologically heterogeneous, and thus the average composition and the average aerodynamic diameter (obtainable by bulk analysis) are not much relevant if the chemical modifications of the particles must be followed. The major elemental composition and abundance of the particle types that are potential subjects of chemical modification can only be obtained using single-particle analysis. A single particle analytical technique, named low-Z particle electron probe X-ray microanalysis (low-Z particle EPMA), was applied to characterize two certified reference materials (CRMs) for Asian Dust particles, which were collected from a loess plateau area and a desert of China. The CRMs were defined by bulk analyses to provide certified concentrations for 13 chemical elements. Using the low-Z particle EPMA technique, the concentrations of major chemical species such as aluminosilicates, SiO2, CaCO3, and carbonaceous species were obtained. Elemental concentrations obtained by the low-Z particle EPMA are close to the certified values, with considering that the single particle and bulk analyses employ very different approaches. There are still some discrepancies between those concentration values, resulting from analyses of particles with different sizes, different sample amounts analyzed, and uncertainties involved in the single particle analysis. [Copyright &y& Elsevier]

Although the identification of events that occur during apoptosis is a fundamental goal of apoptotic cell death research, little is know about the precise sequence of changes in total elemental composition during apoptosis. We evaluated total elemental composition (Na, Mg, P, Cl, S, and K) in relation to molecular and morphological features in human U937 cells induced to undergo apoptosis with staurosporine, an intrinsic pathway activator. To evaluate total elemental content we used electron probe X-ray microanalysis to measure simultaneously all elements from single, individual cells. We observed two phases in the changes in elemental composition (mainly Na, Cl and K). The early phase was characterized by a decrease in intracellular K ( P < 0.001) and Cl ( P < 0.001) content concomitant with cell shrinkage, and preceded the increase in proteolytic activity associated with the activation of caspase-3. The later phase started with caspase-3 activation, and was characterized by a decrease in the K/Na ratio ( P < 0.001) as a consequence of a significant decrease in K and increase in Na content. The inversion of intracellular K and Na content was related with the inhibition of Na+/K+ ATPase. This later phase was also characterized by a significant increase ( P < 0.001) in intracellular Cl with respect to the early phase. In addition, we found a decrease in S content and an increase in the P/S ratio. These distinctive changes coincided with chromatin condensation and DNA fragmentation. Together, these findings support the concept that changes in total elemental composition take place in two phases related with molecular and morphological features during staurosporine-induced apoptosis. [ABSTRACT FROM AUTHOR]

Reports that Leishmania donovani amastigotes mobilize organic and inorganic osmolytes duringregulatory volume decrease. Fluctuation in osmolality; Causative agent of visceral leishmaniasis; Promastigotes that populate the alimentary tract.

Abstract: Accurate estimation of the elemental composition of materials that contain both low- and high-Z elements by electron probe X-ray microanalysis is not an easy task. An example of this kind of material is a new family of ceramics with general formula (Na1−x Bix)(Mn y Nb1−y )O3. To solve this problem, a method based on Monte Carlo simulations combined with an iterative approximation, which was recently successfully applied to quantitative analysis of the elemental content in aerosol particles, was used. The quantification procedure was evaluated on Bi2O3, PbO2 and NaNbO3 particles from stoichiometric compounds and applied to check the homogeneity and elemental contents of the selected ceramic after the application of different heat treatments. [Copyright &y& Elsevier]

The phase equilibria in the Fe–Mg–Zn–O system in the temperature range 1100–1550°C in air have been experimentally studied using equilibration and quenching followed by electron probe X-ray microanalysis. The compositions of condensed phases in equilibrium in the binary MgO–ZnO system and the ternary Fe–Mg–O system have been reported at sub-solidus in air. Pseudo-ternary sections of the quaternary Fe–Mg–Zn–O system at 1100, 1250 and 1400°C in air were constructed using the experimental data. The solid solution of iron oxide, MgO and ZnO in the periclase (Mg, Zn, Fe)O, spinel (Mg2+, Fe2+, Zn2+)xFe3+(2+ y)O4 and zincite (Zn, Mg, Fe)O phases were found to be extensive under the conditions investigated. A continuous spinel solid solution is formed between the magnesioferrite (Mg2+, Fe2+)xFe3+(2+ y)O4 and franklinite (Zn2+, Fe2+)xFe3+(2+ y)O4 end-members at 1100 and 1250°C, extending to magnetite (Fe2+)xFe3+(2+ y)O4 at 1400°C in air. The compositions along the spinel boundaries were found to be non-stoichiometric, the magnitude of the non-stoichiometry being a function of composition and temperature in air. It was found that hematite dissolves neither MgO nor ZnO in air. [ABSTRACT FROM AUTHOR]

A new software tool, the maximum pixel spectrum, detects rare events within a spectrum image data cube, such as that generated with electron-excited energy-dispersive X-ray spectrometry in a scanning electron microscope. The maximum pixel spectrum is a member of a class of‘derived spectra’ that are constructed from the spectrum image data cube. Similar to a conventional spectrum, a derived spectrum is a linear array of intensity vs. channel index that corresponds to photon energy. A derived spectrum has the principal characteristics of a real spectrum so that X-ray peaks can be recognized. A common example of a derived spectrum is the summation spectrum, which is a linear array in which the summation of all pixels within each energy plane gives the intensity value for that channel. The summation spectrum is sensitive to the dominant features of the data cube. The maximum pixel spectrum is constructed by selecting the maximum pixel value within each X-ray energy plane, ignoring the remaining pixels. Peaks corresponding to highly localized trace constituents or foreign contaminants, even those that are confined to one pixel of the image, can be seen at a glance when the maximum pixel spectrum is compared with the summation spectrum. [ABSTRACT FROM AUTHOR]

One of the mechanisms that has been put forward for the development of the androgen-resistant status is neuroendocrine differentiation. Neuroendocrine cells secrete neuropeptides that may represent one of the possible molecular bases by which hormone-dependent prostate cancer cells could escape treatment. LNCaP prostate cancer cells were treated with either etoposide or neuropeptides. Morphological changes related to apoptosis and cell viability were assessed. Changes in intracellular ion content were quantitatively analyzed by electron probe X-ray microanalysis. Etoposide treatment consistently induces a decrease in K and an increase in Na, which are inhibited by bombesin or calcitonin. The Na/K ratio increased markedly after exposure to etoposide, and both bombesin and calcitonin blocked this increase. Etoposide also caused changes in the intracellular P and S concentrations that to a large extent could be blocked by neuropeptides. These results support the hypothesis that neuropeptides confer anti-apoptotic capabilities onto non-neuroendocrine cells in close proximity to neuroendocrine cells. [Copyright &y& Elsevier]

Thin-window electron probe X-ray microanalysis offers new analytical possibilities for low-Z detection (i.e. elements with low atomic number; such as C, N and O). However, the quantitative analysis of individual particles raises some practical questions concerning the technique. From the analytical point of view, beam damage is one of the most important problems due to its big impact on the analysis of individual atmospheric particles. The dependence of the beam-damage effect on the type of collection substrate was studied using standard aerosol particles. Different metallic substrates were rigorously tested in relation to the beam damage effects to different kinds of beam sensitive particles. Ammonium sulfate, ammonium nitrate, sodium nitrate as well as sulfuric acid droplets were analyzed using a liquid nitrogen cooled sample stage on different metallic substrates such as Be, Al, Si and Ag. The obtained results confirm that the use of Be as a collection surface offers some advantages in order to minimize the damage to beam sensitive particles, as suggested in earlier research. [Copyright &y& Elsevier]

Using Monte Carlo simulation, the geometric and matrix effects on intensity and intensity ratio measured by EPMA were investigated for both synthetic particles and biomass burning particles. Three particulate standards, KCl, K2SO4, KHSO4, were prepared and measured along with biomass burning particles. The modified CASINO program (University of Sherbrooke, Quebec, Canada) at the University of Antwerp, Belgium was used. The relative intensities obtained by the UA version of the CASINO program appear to be in line with those from experiments.The CASINO program and iterative procedures were applied to quantitatively determinate the atomic fraction of K, Cl and S in particulate standard and real samples. After correcting the geometric and matrix effects, the atomic fraction ratio of K to Cl in KCl sample was found to be 1.007±0.025, 0.996±0.013 and 1.011±0.019 for experiments with high voltages of 15, 20 and 25 keV, respectively. The same procedure was also applied to K2SO4 and KHSO4 standard particle sample. The atomic fraction ratio of K to S was 1.945±0.049 (25 keV) for K2SO4 and 1.014±0.072 (20 keV) for KHSO4. These ratios obtained are close to the theoretic values 1 or 2. Reasonable data were obtained for biomass burning particles, indicating that it is possible to perform chemical speciation. [Copyright &y& Elsevier]

Experiments were performed to determine whether the transport properties of the ciliary epithelium vary over different regions. Rabbit iris-ciliary bodies were incubated under experimental or control conditions for 30 min before quick freezing, cryosectioning, dehydration and electron probe X-ray microanalysis. Cryosections were cut from three regions along the major axis of the iris-ciliary body, i.e., the anterior, middle and posterior (pars plicata) regions. In bicarbonate/CO2 solution, the epithelial cells of the anterior and middle regions contained more Cl and K than did those of the posterior region. These higher levels of Cl and K were reduced by the carbonic anhydrase inhibitor acetazolamide. Application of bumetanide, an inhibitor of the Na+-K+-2Cl- cotransporter, resulted in significant increases in Cl and K in the anterior and middle regions but not in the posterior region. In bicarbonate-free solution, the ratio for K/Na contents was higher in the posterior than in the two more anterior regions; Na, K and Cl contents of epithelial cells in the three regions were otherwise similar. Cell composition did not differ significantly between the crests and valleys of the posterior region. The divergent responses to perturbation of epithelial transport in the different regions provide the first demonstration of functional heterogeneity along the major axis of the iris-ciliary body. The response to inhibition of carbonic anhydrase raises the possibility that the anterior aspect of the ciliary epithelium may be the major site of aqueous humor secretion. [ABSTRACT FROM AUTHOR]

We describe a simple procedure to prepare cultured cells in suspension to analyse elemental content at the cellular level by electron probe X-ray microanalysis. Cells cultured in suspension were deposited onto polycarbonate tissue, culture plate well inserts, centrifuged at low g, washed to remove the extracellular medium, cryofixed and freeze-dried, and analysed in the scanning mode of a scanning electron microscope. We tested the effect of different washing solutions (150 mm ammonium acetate, 300 mm sucrose, and distilled water) on the elemental content of cultured cells in suspension. The results demonstrated that distilled water was the best washing solution to prepare cultured cells. In addition, the low Na content, high K content and high K/Na ratio of the cells indicated that this procedure, based on the centrifugation at low g followed by cryopreparation, constitutes a satisfactory method to prepare cultured cells in suspension. We also investigated the effects of different accelerating voltages on X-ray signal collection. The results showed that moderate accelerating voltages, i.e. 10–11 kV, should be used to analyse whole cells in the scanning mode of the scanning electron microscope. We show that this method of preparation makes it possible to prepare cryosections of the cultured cells, thus permitting analysis of the elemental content at the subcellular level, i.e. nucleus, cytoplasm and mitochondria, using a scanning transmission electron microscope. [ABSTRACT FROM AUTHOR]

There is increasing evidence that the distribution of monovalent cations in cardiac cells may be non-uniform, particularly in the region immediately beneath the sarcolemma, and we have proposed that a build-up of sodium in this region could be an important factor in the development of ischaemia-reperfusion injury. Electron probe X-ray microanalysis is ideal for the study of such changes in distribution but the application of the technique to this problem imposes severe requirements on the specimen and on the method for cryofixation. The specimen must be perfused through its vasculature so that it can be made truly ischaemic and be successfully reperfused. It is necessary to be able to cryofix the specimen without disturbance of its blood supply, electrical stimulation or temperature. It is also important to know the time in the contraction cycle when cryofixation occurs. Here we describe the design of an automated cryofixation device which can be used to cryofix a blood perfused papillary muscle preparation at predetermined time points in the contraction cycle. Preliminary data obtained from the analysis of rabbit papillary muscles subjected to varying periods of ischaemia are included as an example of the use of the cryoclamp. [ABSTRACT FROM AUTHOR]

The distribution of K, Na and CI in various tissues was studied in two species of lupin, Lupinus luteus L. (ex. Portugal) and L. angustifolius L. (cv. Kubesa) under conditions of NaCl‐induced salinity stress. L. luteus appeared more tolerant to salt and less effective in excluding Na and Cl from its above‐ground parts than L. angustifolius. Electron probe X‐ray microanalysis of vacuolar contents of individual root cells of salt‐treated L. luteus showed a decreasing gradient of Na and CI contents from the epidermis inwards, but in the inner cortical cells adjacent to the pericycle/endodermis, Na levels were again high while Cl remained low. L. luteus may be inefficient in restricting entry of Na into the shoot because of a limited capacity for Na storage in the vacuoles of root cells. In addition, this species appears to exclude Cl from the vacuoles of inner cortical root cells but not from its symplastic pathway. In the leaves of L. luteus, Cl levels were particularly high towards the lower surface (abaxial side), while Na accumulated in the adaxial side of the leaf. Likewise, different cells of the petiole appeared to place unequal demands on Na and Cl for osmotic adjustment. It is suggested that excess Na in the adaxial side of the leaf and the generally high levels of Na and CI in the foliage may explain the 50% fresh weight stimulation which was observed in L. luteus but not in L. angustifolius at 50 mM NaCl. However, the halophytic response of L. luteus is limited to moderate concentrations of NaCl since 100 mM NaCl caused severe necrosis and leaf abscission. [ABSTRACT FROM AUTHOR]

Lupin (Lupinus luteus L. cv. Weiko III) were grown in nutrient solution over a range of inorganic phosphate (Pi) concentrations, with or without 50 mM NaCl. Plants with high Pi (2 mM) and salt showed progressive leaf necrosis and had higher concentrations of total phosphate than plants grown with high Pi alone. Most of the extra total phosphate in salt treated plants was in the Pi form. Pi supply did not influence Na+, K+ or Cl- concentrations in epidermal vacuoles or mesophyll cells. However, epidermal vacuoles accumulated more monovalent cations (Na+ and K+) than Cl-, and in vacuoles of plants grown with 0.1 mM Pi additional Pi was accumulated, possibly to maintain charge balance. Plants grown with 2 mM Pi did not accumulate additional Pi in epidermal vacuoles, but showed higher phosphorus levels in cell walls. It is suggested that at moderate phosphorus concentrations Pi plays a role in epidermal osmotic adjustment, possibly explaining the beneficial role of additional phosphorus on salt stressed plants. At high Pi supply with salt, Pi does not contribute to osmotic adjustment and instead accumulates in cell walls. However, the cause of leaf damage under conditions of high phosphorus supply and salinity is still not entirely clear. [ABSTRACT FROM AUTHOR]

The uptake and distribution of phosphate in lupin ( Lupinus luteus L. cv. Weiko III) roots under moderate salt (NaCl) stress was studied. Vacuolar inorganic phosphate (Pi) concentrations in high phosphate plants were decreased by salt, although whole root Pi was unaffected. In low phosphate plants, vacuolar Pi was unaffected by salt while whole root Pi was increased. Phosphate uptake was not altered by salt in high phosphate plants, but was depressed in low phosphate plants. These observations lead to the conclusion that in high phosphate plants Pi accumulates in cytoplasm and/or stele, ultimately giving rise to phosphate toxicity in shoots. Increasing phosphate supply had no effect on Na+ accumulation in root cell vacuoles in the epidermis or cortex, but the concentration of Cl- in endodermal vacuoles was lowered.

A new approach to the assessment of homogeneity for powder samples of candidate reference materials with the help of electron probe X-ray micro-analysis (EPMA) is proposed. It is based on the utilisation of the Kolmogorov—Smirnov statistics coupled with the Akaike Information Criterion in the processing of the quantitative EPMA data. The evaluation of three IAEA candidate reference materials with the described approach is discussed. [ABSTRACT FROM AUTHOR]

Data on metal-induced elemental changes in eukaryotic unicellular organisms, such as protozoa, are rare. This study focused on two species of ciliate protozoa, Aspidisca cicada and Vorticella convallaria, both common and abundant in activated sludge. Elemental changes in cells exposed to aluminium, copper, and zinc were determined by scanning electron microscopy-electron probe X-ray microanalysis. X-ray emission spectra obtained from cells 2 h after resuspension in Chalkley's medium (control) showed clear, characteristic peaks for magnesium, silicon, phosphorus, sulphur, potassium, and copper. These elements were also routinely detected in all cells resuspended in metal solution. Spectra obtained from cells treated with aluminium or zinc showed additional distinct peaks for aluminium and zinc. In copper-treated cells enhanced copper peaks were seen. Mean aluminium levels were low in A. cicada control cells (0.14mg/g of dry weight) but higher in cells treated with 0.50 ppm (0.69 mg/g of dry weight) and 2.00 ppm aluminium (2.07 mg/g of dry weight). A. cicada was ten times more sensitive to copper than to the other metals, and than V. convallaria. There was a significantly higher concentration of copper in A. cicada cells treated with 0.20 ppm copper (2.94 mg/g of dry weight) than in control cells (2.16 mg/g of dry weight). In A. cicada cells treated with 0.50 and 2.00 ppm zinc significantly higher levels of zinc (2.41 and 2.07 mg/g of dry weight, respectively) were observed than in the control (0.41 mg/g of dry weight). After treatment with 0.50 ppm and 2.00 ppm aluminium, aluminium was significantly higher in the treated V. convallaria cells (1.58 and 0.67 mg/g of dry weight, respectively) than in control cells (0.14 mg/g of dry weight). After treatment with 2.00 ppm copper there was significantly more copper in treated V. convallaria cells (3.63 mg/g of dry weight) than in controls (2.08 mg/g of dry weight). In V. convallaria cells treated with 0.50 ppm and 2.00 ppm zinc there was an increase in the amount of zinc in cells (1.30 and 2.68 mg/g of dry weight, respectively) compared with control cells (0.34 mg/g of dry weight). Data on other changes in intracellular elements in both species, after 2 h exposure to aluminium, copper, and zinc medium are given. In both species, there was uptake and/or accumulation of aluminium, copper, and zinc when the external concentration of the metal was increased. Intracellular elemental levels were altered by sublethal and toxic external concentrations of the metals studied. A. cicada was ten times more sensitive to copper than to aluminium or zinc, and than V. convallaria to the metals studied. [ABSTRACT FROM AUTHOR]

K efflux provoked by ethidium proceeds partially as an all-or-none effect by which the diffusion barrier for K is disrupted and partially from still intact cells, presumably by exchange against ethidium. This is shown by the application of an electron probe microanalysis X-ray technique by which the K content of a number of individual cells is analyzed. [ABSTRACT FROM AUTHOR]