Effect of Cd++ on germination,growth and active principles of Datura metel L.∗

The effects of Cd⁺⁺ concentration increment in soil and/or in atmosphere, on germination, growth and alkaloid contents of Datura metel L. were investigated. We observed a significant reduction of growth following addition of Cd⁺⁺ in soil. Minor effects on growth were evident when the plants were sprayed with CdCl₂ solution (10mgCd⁺⁺/l).

Scanning electron microscope observation showed stomata widely open and conspicuous cuticular striations in the foliar epidermis of polluted plants.

GLC analysis of extracts evidenced a significant variation in active principle content among plants undergoing different treatments.     

Changes of Surface Properties of Yeast Cell Wall Under Exposure of Electromagnetic Field (40.68 MHz) and Action of Nystatin

Summary Changes of the surface properties were studied in the cell wall of the yeast Saccharomyces cerevisiae Y-517 under influence of the electromagnetic field (EMF) (40.68 MHz) and lethal doses of the fungicidal antibiotic nystatin (10 μg/10⁶ cells). Atomic force microscopy was used to study surface topography and visco-elastic properties of the cell walls. Surface carbohydrates were detected by lectins marked with gold with the help of the scanning electron microscope. Additional polysaccharide layer appeared over cell surface after EMF exposure. We suggest that electromagnetic fields resulted in the change of the cell surface, and, accordingly, the sensitivity of organisms to the antifungal antibiotics.     

Visualization of the Malleability of the Rubber Core of Rubber Particles from Parthenium argentatum Gray and Other Rubber-Producing Species Under Extremely Cold Temperatures

Rubber particles from Parthenium argentatum Gray (guayule) were frozen in liquid nitrogen (–196°C), fractured, and visualized using cryo-scanning electron microscopy. We observed that the rubber polymer core of the rubber particles was still malleable at this extremely cold temperature, and the core stretched substantially during separation of the fracture planes. This malleability was observed in situ in tissue sections, as well as in purified rubber particles, and was found to be independent of purification procedure, guayule line, tissue age, or season. The malleability or stretching phenomenon suggests that P. argentatum rubber has some unique properties because rubber particles from Hevea brasiliensis Müll. Arg. and Ficus elastica Roxb. were brittle at this temperature, fractured cleanly, or showed only tiny threads of material pulling out of the core.     

好氧颗粒污泥藻酸盐提取物的聚集形态研究

为探寻细菌藻酸盐对好氧污泥颗粒化的作用,借鉴海藻酸盐的提取方法,将好氧颗粒污泥中的细菌藻酸盐提取和鉴定后,对10～500mg·L-1,范围内不同浓度的藻酸盐提取物在50mg·L-1CaCl2溶液中的聚集形态进行了原子力显微镜观察.结果表明,细菌藻酸盐占好氧颗粒污泥干重的35.1%±1.9%.在CaCl2作用下,藻酸盐提取物具有从无序聚集成有序状态的超分子自组装特性,随着浓度的增加,藻酸盐提取物自发聚集,由纳米级的胶束微球聚集为微米级的花状,进而连接成网状成层堆积.好氧颗粒污泥中细菌藻酸盐通过形成具有三维空间结构的细菌藻酸盐-金属凝胶而对颗粒污泥的形成起骨架作用.其中,细菌藻酸盐-Ca2 凝胶在颗粒污泥的形成和维持其稳定结构中起主要作用.     

微波作用下表面活性剂在膨润土上的吸附行为特征

探讨了微波辐照时间、CPC浓度对微波合成有机膨润土的层间距、有机碳含量的影响,以及CPC在有机膨润土合成过程中的吸附动力学与热力学.结果表明,微波辐照90～120 s时,CPC在膨润土的饱和吸附量与常规合成的相当,达0 .001?63 mol·g^-1,当微波辐照2 min时,CPC浓度为1 .20 mmol·L^-1时,合成的有机膨润土的层间距达到最佳的2 .44 nm,有机碳含量达23 .45%; AFM分析表明微波不会破坏膨润土的层状结构;微波对CPC在膨润土上的吸附有较大的影响,可提高吸附反应速度常数107 .6倍,并降低体系的自由能.     

Biochemical and histopathological ultrastructural changes caused by ZnO nanoparticles in mice

Five week-old mice were divided into a vehicle control group, and groups exposed to ZnO nanoparticles at low (0.5 g/kg), middle (1 g/kg), high (3 g/kg), and exceptionally high-dose (5 g/kg). After the first, second, third, and fourth weeks’ of exposure, blood biochemistry, histopathology, and electron microscopic ultrastructural changes in liver, kidney and spleen were investigated. Increased alkaline phosphatase activities were observed in all treated mice being statistically significant at higher dose. No changes were observed in the serum glutamic pyruvic transaminase, serum glutamic oxaloacetic transaminase, creatinine, blood urea nitrogen, and lipid levels. During the first and second weeks of the treatment, effects on the cytoarchitecture of liver, kidney, and spleen were not perceived while during the third and fouth weeks of treatment sporadic mild effects were seen. Ultrastructural electron microscopic changes in liver, kidney, and spleen were not observed for the low-dose group on the first, second, third, and fourth weeks, suggesting that exposure to ZnO nanoparticles at low dose is safe. Long-term (i.e., more than 28 days) exposure to the exceptionally high-dose resulted in sporadic changes in nuclear chromatin condensation, irregular nuclear membrane, polymorphic mitochondria, mitochondrial swelling, and vacuolation. ZnO nanoparticles could be well tolerated and no death occurred in any group of treated mice.     

ESEM–EDX characterisation of airborne particles from an industrialised area of northern Greece

The aim of this study was to characterise individual airborne particles collected from the Ptolemais-Kozani region (Western Macedonia), northern Greece. Throughout a 1-year period (March 2003 to February 2004), we collected several filters that captured airborne particles at seven sampling sites distributed throughout the area. The airborne particles captured on the filters were then characterised by environmental scanning electron microscopy (ESEM) coupled with energy-dispersive X-ray analysis (EDX). The particles were categorised as geogenic, biogenic and anthropogenic. The main anthropogenic airborne particles were fly ash (released from lignite-fired power plants) and carbonaceous (soot and char) and metalliferous (mainly iron- and copper-enriched) particulates. We present here characteristic ESEM and EDX spectra for the airborne particles and underline the presence of characteristic primary and secondary sulphates.     

Relationship of surface changes to metal leaching from tungsten composite shot exposed to three different soil types

Physical changes that occur on the surface of fired shots due to firing and impact with soil may increase the dissolution of muniton metals. Increased metal dissolution could potentially increase metal transport and leaching, affecting metal concentrations in surface and groundwater. This research describes the relationship between the surface changes on fired tungsten-nickel-iron (94% W:2% Ni:4% Fe) composite shots and metals leaching from those shots. Tungsten composite shot was fired into, and aged in, three soil types (Silty Sand, Sandy Clay, and Silt) in mesoscale rainfall lysimeters to simulate live-fire conditions and subsequent interactions between the metals of the composite and soil. Leachate, runoff, and soil samples were collected from the lysimeters and analyzed for metal content. The shots were analyzed using scanning electron microscopy (SEM) to evaluate surface changes. SEM results indicated that a soil’s particle size distribution initially affected the amount of metal that was sheared from the surface of the fired W-composite shots. Shearing was greatest in soils with larger soil particles (sand and gravel); shearing was least in soils composed of small soil particles (fines). Increased metallic shearing from the shot’s surface was associated with increased W dissolution, compared to controls, following a simulated 1 year soil aging.     

Apolipophorin III and transmission electron microscopy as toxicity indicators for harmaline and tea saponin in Spodoptera exigua (Noctuidae: Lepidoptera)

Apolipophorin III, traditionally known for lipid transport in insects is fairly established as toxicity indicator against harmaline and tea saponin during this study. Apolipophorin III expressed in the hemolymph and midgut tissues of 3rd, 4th, 5th larval instars and pupae of Spodoptera exigua. Apolipophorin III presence was further confirmed by achieving its partial cDNA (Genbank accession no. FJ606822) of 448 bp. qRT PCR revealed that tea saponin resulted in significant reduction of gene expression in 3rd and 4th larval instars but increased in 5th instar as compared to control. Harmaline caused gradual increase of gene expression in 3rd, 4th and 5th instars after feeding on the treated diet. Fifth instar larvae synonymously resulted in the highest gene expressions against both the biochemicals. After the injection of harmaline and tea saponin abrupt increase in gene expression of 4th, 5th larval instar and pupae was observed as compared to control treatment. Transmission electron microscopy of midgut epithelium after being fed with harmaline and tea saponin depicted certain cytological changes. Harmaline treatment lead to cytoplasm vacuolization, mitochondrial disruption, spherocrystals with concentric layers, irregular nucleus and floating nuclei in cytoplasm. Tea saponin treatment resulted in denser cytoplasm, higher intracellular osmotic concentration and reduced complement of apical microvilli. Cells were found to have only a few mitochondria and glycogen deposits in comparison to control treatment.     

Phenanthrene uptake by Medicago sativa L. under the influence of an arbuscular mycorrhizal fungus

Phenanthrene uptake by Medicago sativa L. was investigated under the influence of an arbuscular mycorrhizal fungus. Inoculation of lucerne with the arbuscular mycorrhizal fungus Glomus etunicatum L. resulted in higher phenanthrene accumulation in the roots and lower accumulation in the shoots compared to non-mycorrhizal controls. Studies on sorption and desorption of phenanthrene by roots and characterization of heterogeneity of mycorrhizal and non-mycorrhizal roots using solid-state ¹³C nuclear magnetic resonance spectroscopy (¹³C NMR) demonstrated that increased aromatic components due to mycorrhizal inoculation resulted in enhanced phenanthrene uptake by the roots but lower translocation to the shoots. Direct visualization using two-photon excitation microscopy (TPEM) revealed higher phenanthrene accumulation in epidermal cells of roots and lower transport into the root interior and stem in mycorrhizal plants than in non-mycorrhizal controls. These results provide some insight into the mechanisms by which arbuscular mycorrhizal inoculation may influence the uptake of organic contaminants by plants.