Localisation of hydrogen peroxide accumulation during Solanum tuberosum cv. Rywal hypersensitive response to Potato virus Y

The reactive oxygen species hydrogen peroxide (H₂O₂) was detected cytochemically in Solanum tuberosum cv. Rywal tissues as a hypersensitive response (HR) 24 and 48 h after a Potato virus Y (PVY) infection.Hydrogen peroxide was detected in vivo by its reaction with 3.3-diaminobenzidine, producing a reddish-brown staining in contact with H₂O₂. Hydrogen peroxide was detected in the necrotic area of the epidermal and mesophyll cells 24 and 48 h after the PVY infection. Highly localised accumulations of H₂O₂ were found within xylem tracheary elements, and this was much more intensive than in non-infected leaves. Hydrogen peroxide was detected cytochemically in HR also by its reaction with cerium chloride, producing electron-dense deposits of cerium perhydroxides.Inoculation with PVY^NTN and also PVY^N Wi induced a rapid hypersensitive response during which highly localised accumulations of H₂O₂ was detected in plant cell walls. The most intensive accumulation was present in the bordering cell walls of necrotic mesophyll cells and the adjacent non-necrotic mesophyll cells. Intensive electron-dense deposits of cerium perhydroxide were found along ER cistrenae and chloroplast envelopes connected with PVY particles. The precipitates of hydrogen peroxide were detected in the nuclear envelope and along tracheary elements, especially when virus particles were present inside. The intensive accumulation of H₂O₂ at the early stages of potato–PVY interaction is consistent with its role as an antimicrobial agent and for this reason it has been regarded as a signalling molecule.     

Subcellular localization of calcium deposits during zebrafish (Danio rerio) oogenesis

Calcium plays prominent roles in regulating a broad range of physiological events in reproduction. The aim of this study was to describe the subcellular distribution of calcium deposits during stages of oogenesis in zebrafish using a combined oxalate–pyroantimonate technique. The oocyte development of zebrafish was categorized into four stages: primary growth, cortical-alveolus, vitellogenic, and maturation, based on morphological criteria. Calcium deposits in the primary growth stage were detected in the cytoplasm, mitochondria, nucleus, and follicular cells. At the cortical-alveolus stage, calcium particles were transported from follicular cells and deposited in the cortical alveoli. In the vitellogenic stage, some cortical alveoli were compacted and transformed from flocculent electron-lucent to electron-dense objects with the progression of the stage. Calcium deposits were transformed from larger to smaller particles, coinciding with compaction of cortical alveoli. In the maturation stage, calcium deposits in all oocyte compartments decreased, with the exception of those in mitochondria. The proportion of area covered by calcium deposits in the mitochondria and cortical alveoli of oocytes at different stages of development was significantly different (p < 0.05). The extent of calcium deposits in the cortical alveoli of mature oocytes was substantially lower than in earlier stages. Basic information about calcium distribution during zebrafish oogenesis may contribute to better understanding of its role in oogenesis.     

Cytopathological potato virus Y structures during Solanaceous plants infection

The ultrastructural analysis of tobacco, potato and pepper tissues during infection with necrotic strains and the ordinary Potato virus Y strain of revealed the presence of virus inclusions not only in the epidermis and mesophyll but also in the vascular tissues. For the first time cytoplasmic inclusions were documented in companion cells and phloem parenchyma as well as in xylem tracheary elements. The ultrastructural features studied in this work consisted of mostly laminated inclusions (in the traverse and longitudinal section), which were frequently connected with enlarged cisternae of endoplasmic reticulum (ER) located in the direct vicinity of the cell wall attached to virus particles opposite to plasmodesmata. It was noticed that ER participates in synthesis and condensation of the PVY inclusions. During compatible interaction of tobacco and potato plants with PVY, amorphous and nuclear inclusions were observed. Such forms were not found in pepper tissues and potato revealing the hypersensitivity reaction to the infection with PVY necrotic strains. It was stated that the forms of cytoplasmic inclusions cannot serve as a cytological criterion to distinguish the potato virus Y strains and do not depend on host resistance level. Only in compatible interaction in Solanaceous plants tissues cytoplasmic inclusions were observed from the moment the morphological symptoms appeared. In the reaction of hypersensitivity, the inclusions were found on the 24th day following the infection with the PVY necrotic strains, whereas the symptoms were observed 3 days after the PVY infection.     

Microscopical and functional aspects of calcium-transport and deposition in terrestrial isopods

Terrestrial isopods (Crustacea) are excellent model organisms to study epithelial calcium-transport and the regulation of biomineralization processes. They molt frequently and resorb cuticular CaCO(3) before the molt to prevent excessive loss of Ca(2+) ions when the old cuticle is shed. The resorbed mineral is stored in CaCO(3) deposits within the ecdysial gap of the first four anterior sternites. After the molt, the deposits are quickly resorbed to mineralise the posterior part of the new cuticle. The deposits contain numerous small spherules composed of an organic matrix and amorphous CaCO(3), which has a high solubility and, therefore, facilitates quick mobilization of Ca(2+) and HCO(3)(-) ions. During the formation and resorption of the deposits large amounts of Ca(2+), HCO(3)(-) and H(+) are transported across the anterior sternal epithelial cells. Within the last years, various light and electron microscopical techniques have been used to characterize the CaCO(3) deposits and the cellular mechanisms involved in biomineralization. The work on the CaCO(3) deposits includes studies on the ultrastructure of the deposits, the sequence of events during deposit formation and dissolution, and the mineral composition of the sternal deposits. The differentiation of the anterior sternal epithelial cells and the mechanisms of epithelial ion transport required for the mineralization and demineralisation of the deposits was studied using various analytical light and electron microscopical techniques including polarized light microscopy, immunocytochemistry, electron microprobe analysis, electron energy loss spectroscopy and electron spectroscopic imaging. Comparative analysis of deposit morphology and the differentiation of the sternal epithelia provide information on the evolution of CaCO(3) deposit formation in relation to the degree of adaptation to terrestrial environments.     

The evidence of Tobacco rattle virus impact on host plant organelles ultrastructure

Tobraviruses, like other (+) stranded RNA viruses of plants, replicate their genome in cytoplasm and use such usual membranous structures like endoplasmic reticulum. Based on the ultrastructural examination of Tobacco rattle virus (TRV)-infected potato and tobacco leaf tissues, in this work we provide evidence of the participation of not only the membranous and vesicular ER structures but also other cell organelles during the viral infection cycle. Non-capsidated TRV PSG particles (potato isolate from the Netherlands) (long and short forms) were observed inside the nucleus while the presence of TRV capsid protein (CP) was detected in the nucleus caryolymph and within the nucleolus area. Both capsidated and non-capsidated viral particles were localized inside the strongly disorganized chloroplasts and mitochondria. The electron-dense TRV particles were connected with vesicular structures of mitochondria as well as with chloroplasts in both potato and tobacco tissues. At 15–30 days after infection, vesicles filled with TRV short particles were visible in mitochondria revealing the expanded cristae structures. Immunodetection analysis revealed the TRV PSG CP epitope inside chloroplast with disorganized thylakoids structure as well as in mitochondria of different tobacco and potato tissues. The ultrastructural analysis demonstrated high dynamics of the main cell organelles during the TRV PSG–Solanaceous plants interactions. Moreover, our results suggest a relationship between organelle changes and different stages of virus infection cycle and/or particle formation.     

Nuclear microscopy of normal and necrotic skeletal muscle fibers: an intracellular elemental microanalysis

The in situ total elemental composition and elemental concentrations present in mouse soleus (type I) and gastrocnemius (type IIA) muscle fibers were analyzed by using nuclear microscopy (NM). Elemental changes in necrotic fibers, induced by intramuscluar injection with snake venom (Pseudechis australis), were also studied 3 h post-injection. Nuclear microscopy is a new method based on nuclear technology that utilizes the interaction between a million-electron-volt nuclear particle beam and the muscle sample (in the case of the present study). Elemental analysis was done at the parts per million (ppm) level of sensitivity on unfixed, rapidly frozen and unstained single fast- and slow-twitch muscle fibers with imaging capabilities of μm spatial resolution and in multi-elemental mode. In total, 12 different intracellular elements were mapped, co-localized and analyzed in single normal and necrotic skeletal muscle fibers from mice. Elements such as potassium, sulfur, phosphorus, chlorine and sodium were found in concentrations from 1000 to 18 000 ppm. Unlike conventional electron-probe X-ray microanalysis, NM also detected and analyzed the trace elements such as magnesium, calcium, iron and zinc that were found in concentrations of 50 to 1000 ppm. Other elements — copper, manganese and rubidium — were also detected in concentrations of less than 50 ppm. The trace elements calcium, iron and zinc were more abundant in the soleus than the gastrocnemius (the level of iron was statistically significant). Calcium, sodium and chlorine were significantly elevated in venom-induced necrotic soleus muscle fibers.     

Influence of amphotericin B on liquid crystal state of the Cholesterol/Dipalmitoylphosphatidylcholine monolayer in the presence of different metal cations

Amphotericin B is a very effective antifungal drug,but it has an adverse reaction to the membrane of mammals' cells.The interaction between Am B and cholesterol(Chol) causes the formation of pores on the membrane to destroy its integrity.In particular,Am B has a significant effect on the permeability of membrane for K~+ions.It has been reported that Na+ions and Ca~(2+)ions may have some influence on the interaction between amphotericin B and lipid molecules.In this work,the effects of these metal cations on the physical state and intermolecular interaction of the Cholesterol/Dipalmitoylphosphatidylcholine(Chol/DPPC) monolayer with and without Am B have been investigated.The addition of Am B induces the change of physical state of the lipid monolayer from liquid-gel phase to liquid phase.Different metal cations could influence the phase transition of the Am B-lipid monolayer.The K~+ions and Ca2+ions make the obvious phase transition disappear.However,the presence of Na+ions has little influence on the phase transition of the Am B-lipid monolayer.The addition of Am B and the presence of different metal cations weaken the attractive force on the monolayers.After addition of Am B,the force between the molecules is the strongest in the environment of K+ions,thus is the weakest in the environment of Ca~(2+)ions,which may be due to the distribution of these metal cations inside and outside of cells.A large number of K+ions distribute inside of the cells,thus most of Na+and Ca~(2+)ions exist out of the cells.Hence,it may be possible that when Am B molecules are out of the cells,the reaction between the drug and lipid molecules is weaker than that inside the cells.These results may have a great reference value for further studying the toxicity mechanism of Am B and the influence of metal cations on the membrane.     

Ultrastructural localization of Trypanosoma cruzi lysosomes by aryl sulphatase cytochemistry

Lysosomes of trypanosomatid protozoa are poorly known. In this work we have cytochemically detected the lysosomal enzyme aryl sulphatase in the trypanosomatids Trypanosoma cruzi and Crithidia fasciculata, by using p-nitrocatecholsulphate as substrate. Positive reaction was located exclusively inside membrane-bound cytoplasmic vesicles distributed throughout the cell body. Electron-dense reaction was either dispersed homogeneously through the vesicular matrix or located at the vesicle periphery, apposed to the membrane, with fine granular deposits occasionally found at the vesicular matrix. Trypomastigote and epimastigote forms of T. cruzi lacked electron-dense deposits at the plasma membrane, thus indicating that aryl sulphatase was not secreted to the environment. Furthermore, no positive reaction was detected in epimastigote reservosomes, which are organelles considered as pre-lysosomal compartments. Thus, our data show that reservosomes and lysosomes are organelles that can be distinguished by the cytochemical localization of aryl sulphatase in T. cruzi epimastigotes and trypomastigotes. Positive reaction in cytoplasmic vesicles of C. fasciculata choanomastigotes confirmed the specificity of the reaction for lysosomes in other trypanosomatid species.     

Hydrodynamic cavitation efficiently inactivates potato virus Y in water

Waterborne plant viruses can destroy entire crops, leading not only to high financial losses but also to food shortages. Potato virus Y (PVY) is the most important potato viral pathogen that can also affect other valuable crops. Recently, it has been confirmed that this virus is capable of infecting host plants via water, emphasizing the relevance of using proper strategies to treat recycled water in order to prevent the spread of the infectious agents. Emerging environmentally friendly methods such as hydrodynamic cavitation (HC) provide a great alternative for treating recycled water used for irrigation. In the experiments conducted in this study, laboratory HC based on Venturi constriction with a sample volume of 1 L was used to treat water samples spiked with purified PVY virions. The ability of the virus to infect plants was abolished after 500 HC passes, corresponding to 50 min of treatment under pressure difference of 7 bar. In some cases, shorter treatments of 125 or 250 passes were also sufficient for virus inactivation. The HC treatment disrupted the integrity of viral particles, which also led to a minor damage of viral RNA. Reactive species, including singlet oxygen, hydroxyl radicals, and hydrogen peroxide, were not primarily responsible for PVY inactivation during HC treatment, suggesting that mechanical effects are likely the driving force of virus inactivation. This pioneering study, the first to investigate eukaryotic virus inactivation by HC, will inspire additional research in this field enabling further improvement of HC as a water decontamination technology.     

Ferritin in iron containing granules from the fat body of the honeybees Apis mellifera and Scaptotrigona postica

It is already known that the behaviour of the honeybee Apis mellifera is influenced by the Earth's magnetic field. Recently it has been proposed that iron-rich granules found inside the fat body cells of this honeybee had small magnetite crystals that were responsible for this behaviour. In the present work, we studied the iron containing granules from queens of two species of honeybees (A. mellifera and Scaptotrigona postica) by electron microscopy methods in order to clarify this point. The granules were found inside rough endoplasmic reticulum cisternae. Energy dispersive X-ray analysis of granules from A. mellifera showed the presence of iron, phosphorus and calcium. The same analysis performed on the granules of S. postica also indicated the presence of these elements along with the additional element magnesium. The granules of A. mellifera were composed of apoferritin-like particles in the periphery while in the core, clusters of organised particles resembling holoferritin were seen. The larger and more mineralised granules of S. postica presented structures resembling ferritin cores in the periphery, and smaller electron dense particles inside the bulk. Electron spectroscopic images of the granules from A. mellifera showed that iron, oxygen and phosphorus were co-localised in the ferritin-like deposits. These results indicate that the iron-rich granules of these honeybees are formed by accumulation of ferritin and its degraded forms together with elements present inside the rough endoplasmic reticulum, such as phosphorus, calcium and magnesium. It is suggested that the high level of phosphate in the milieu would prevent the crystallisation of iron oxides in these structures, making very unlikely their participation in magnetoreception mechanisms. They are most probably involved in iron homeostasis.     

Imaging of Ca(2)+ intracellular dynamics with a third-harmonic generation microscope

We describe the promising development of third-harmonic generation (THG) in laser scanning microscopy for study of the functional imaging of live biological cells. The dynamics of Ca(2+) in biological cells is shown. The Ca(2+) signal consists of a transient increase in the intracellular concentration. THG microscopy allows one to temporally visualize the release of Ca(2+) from internal stores and (or) calcium influx.     

Infrared femtosecond laser pulse induced permanent reduction of Eu3+ to Eu2+ in a fluorozirconate glass

We report what is believed to be the first observation of permanent photoreduction of Eu(3+) to Eu(2+) in transparent and colorless Eu(3+) -doped fluorozirconate glass at room temperature, using an infrared femtosecond laser. Difference absorption and electron-spin-resonance spectra of the glass before and after laser irradiation showed that a portion of the Eu(3+) ions in the focused part of the laser inside the glass were reduced to Eu(2+) ions after laser irradiation. It is suggested that Eu(3+) ions act as electron-trapping centers, whereas active sites in the glass matrix act as hole-trapping centers, leading to the formation of Eu(2+) ions. The observed phenomenon is inferred to be useful in the fabrication of optical memory devices with high storage density and waveguide-type micro-optical devices.     

基于光谱学分析的水泥基渗透结晶防水材料作用机理探讨

以渗透结晶防水材料为研究对象,将渗透结晶防水材料掺入水泥基材料制备水泥基渗透结晶防水材料。基于X射线衍射仪(XRD)和傅里叶红外光谱仪(FTIR)分析了渗透结晶防水材料的组分,在此基础上研究了渗透结晶防水材料对构件力学性能的影响,利用扫描电子显微镜(SEM)与X射线衍射仪(XRD)对水泥基渗透结晶防水材料构件的微观形貌和物相组成进行分析,结合抗压强度回复率、抗渗压力等相关数据,阐明水泥基渗透结晶防水材料作用机理。研究表明,渗透结晶防水材料的主要成分为氧化钙、硅酸钠、二硅酸钠、碳酸钙、氢氧化钙、稠环芳烃类减水剂、乙二胺四乙酸盐。掺入渗透结晶防水材料的水泥基渗透结晶防水材料,其力学性能、抗渗性能、自愈合性能优越,即7,14和28 d的抗折强度分别为2.65,3.29和4.35 MPa,抗压强度分别为12.11,14.57和16.77 MPa;一次抗渗压力与二次抗渗压力分别为0.8和0.9 MPa;7,14,28和56 d的抗压回复率分别为80.91%,90.35%,100.44%和105.90%。水泥基渗透结晶防水材料的作用机理：渗透结晶防水材料中硅酸钠、二硅酸钠与水泥中的钙离子发生反应形成水化硅酸钙凝胶(C—S—H凝胶),有效修补裂缝;氧化钙、碳酸钙以及氢氧化钙作为钙离子补偿剂提供大量钙离子,在水环境下有效促使裂缝愈合;碳酸钙在水环境中缓慢溶解产生Ca2+,CO2-₃以及HCO-₃,CO2-₃与HCO-₃结合大量钙离子生成碳酸钙结晶,与C—S—H凝胶协同作用对水泥基材料的裂缝进行封堵。     

Chemical Analysis of Hydroxyapatite Artificial Bone Powders by Energy Dispersive X-Ray Fluorescence Spectrometry(EDXRF)

Stoichiometric hydroxyapatite (HA) nanoparticles were synthesized by a wet chemical method. Calcium nitrate tetra hydrate used as calcium source and dibasic ammonium phosphate used as phosphorous source. Calcium nitrate tetra hydrate and dibasic ammonium phosphate solutions were prepared by dissolving the salts in distilled water. Stoichiometric hydroxyapatite nanoparticles used by artificial bone powders and synthesized by a wet chemical method were analyzed using EDXRF method.The concentrations of K, Ca, Ti, V, Cr, Fe, Ni, Cu, Sr and Pb for artificial bone powders have been determined. Besides, Calcium contents were evaluated according to the agitation time and temperature in the production process.     

GFAAS测定微量铍的阳离子干扰研究

石墨炉原子吸收光谱法(GFAAS)是测定微量铍的主要方法,但干扰因素很多.本文在没有背景校正和基体改进的情况下,建立了一个一次多元线性回归模型,并采用正交回归设计方法定量研究了常见阳离子钾、钠、钙、镁和铝对测量铍的干扰.结果表明,GFAAS法测定微量铍时,钾和钠对测量的影响可以忽略不计,而钙、镁和铝对测量有增敏作用,镁和铝还存在交互效应,对测量有抑制作用.离子干扰的 定量回归方程为:A＝-0.0059 0.0104(Ca2 ) 0.0874(Mg2 ) 0.1077(Al3 )-0.0239(Mg2 )(Al3 ),式中(Ca2 )表示lg([Ca2 ]/[Be2 ]),以此类推.     

Cytochemical localization of calcium and X-ray microanalysis of Catharanthus roseus L. infected with phytoplasmas

The potassium pyroantimonate (KPA) Ca²⁺ precipitation technique, X-ray microanalysis and Electron Energy Loss Spectroscopy carried out by transmission electron microscopy were used to analyze the Ca²⁺ distribution in Catharanthus roseus L. leaves infected with phytoplasmas belonging to different taxonomic groups, and in phytoplasma cells. The analysis revealed that the distribution of Ca²⁺ was different in healthy and diseased plants (where the KPA deposits were numerous) and no differences were observed in the tissues of the three types of infected C. roseus L. Since no KPA precipitates were visible in the phloem and on phytoplasma cells, it is likely that Ca²⁺ ions are not directly involved in phytoplasma replication, but, in infected cells is a response to the pathogen indicative of a higher Ca²⁺ in the plasmalemma.     

Calcium permeation property and firmness change of cherry tomatoes under ultrasound combined with calcium lactate treatment

This study aimed to investigate the effect of ultrasound combined with calcium lactate (2%, w/v) treatment (U + Ca) on calcium permeation and firmness of cherry tomatoes. Calcium distribution and fruit pectin nanostructure were also analysed by transmission electron microscope (TEM) and atomic force microscopy (AFM), respectively. The firmness (31.45 N) was maintained when ultrasound energy density was 20 W/L for 15 min at 15 °C. The Ca content increased in U + Ca treated fruit. Meanwhile, the Peleg’s model could be used to express the change of solid gain in cherry tomatoes under ultrasound treatment at 15, 20, and 25 °C. According to the AFM results, the width (≥40 nm) and length (≥2 μm) of chelate-soluble pectin (CSP) and sodium carbonate-soluble pectin (SSP) chains with large frequency was observed in U + Ca treated fruit. Under desirable conditions (15 °C, 15 min, 20 W/L), ultrasound combined with calcium lactate could maintain the quality of cherry tomatoes.     

高铁酸钾制备新方法与光谱表征

以次氯酸钙为原料制备了高纯度高铁酸钾,研究内容包括:高铁酸钾的性质反应温度对产率的影响,重结晶温度对产率的影响,反应时间对产率的影响,次氯酸钙用量对产率的影响。确定了反应温度为25℃,重结晶温度为0℃,反应时间为40 min,反应所需的次氯酸钙用量为理论用量的1.2倍,产率为75%以上。利用直接分光光度法对产物纯度进行了分析,测得产物纯度达到92%以上。论文以红外光谱法、紫外分光光度法、X衍射法对产物进行表征,证明以次氯酸钙为原料制得的产物为高铁酸钾。     

Ultrastructural insights into tomato infections caused by three different pathotypes of Pepino mosaic virus and immunolocalization of viral coat proteins

This paper presents studies on an ultrastructural analysis of plant tissue infected with different pathotypes of Pepino mosaic virus (PepMV) and the immunolocalization of viral coat proteins. Because the PepMV virus replicates with a high mutation rate and exhibits significant genetic diversity, therefore, isolates of PepMV display a wide range of symptoms on infected plants. In this work, tomato plants of the Beta Lux cultivar were inoculated mechanically with three pathotypes representing the Chilean 2 (CH2) genotype: mild (PepMV-P22), necrotic (PepMV-P19) and yellowing (PepMV-P5-IY). The presence of viral particles in all infected plants in the different compartments of various cell types (i.e. spongy and palisade mesophyll, sieve elements and xylem vessels) was revealed via ultrastructural analyses. For the first time, it was possible to demonstrate the presence of crystalline inclusions, composed of virus-like particles. In the later stage of PepMV infection (14 dpi) various pathotype-dependent changes in the structure of the individual organelles (i.e. mitochondria, chloroplasts) were found. The strongest immunogold labeling of the viral coat proteins was also observed in plants infected by necrotic isolates. A large number of viral coat proteins were marked in the plant conductive elements, both xylem and phloem.     

Synthesis and Luminescence Properties of Trivalent Rare-Earth Element-Doped Calcium Stannate Phosphors

The phosphors of calcium stannate activated with individual trivalent rare-earth element (REE) ions (Neodymium III, Europium III, Terbium III, Dysprosium III, and Samarium III) were synthesized by high-temperature solid-state reaction (SSR), and their characterization and luminescent properties were investigated. The crystal structures and morphologies of the resultant materials were well characterized by experimental techniques such as X-ray powder diffraction (XRD) and environmental scanning electron microscopy (ESEM). The XRD results display that the rare-earths substitution of Calcium II does not change the structure of calcium stannate host. Obviously, the ESEM image exhibits that phosphors aggregate and their particles with irregular shape exist. The calcined powders of the Europium III, Neodymium III, Samarium III, Dysprosium III, and Terbium III ions doped in calcium stannate exhibits bright red, reddish orange, yellowish, orange white, and green light, respectively. Although there is some intrinsic emission ranging from UV to near-infrared (NIR) due to the host lattice, the dominant signals are from the rare-earth sites, with signals characteristic of the trivalent rare-earth states. The emission spectrum from undoped-calcium stannate phosphor is characterized by two broad bands centered at ～800 and ～950 nm. The shapes of the emission bands are different for each dopant. The sharp emission properties show that the calcium stannate is a suitable host for rare-earth ion-doped phosphor material. Furthermore the influence of different rare-earth dopants, that is, Europium III, Neodymium III, Samarium III, Dysprosium III, and Terbium III, on thermally stimulated luminescence (TSL) of calcium stannate phosphor under the beta irradiation was discussed. Among these trivalent rare-earth-doped phosphors samarium-doped material showed maximum TSL sensitivity with favorable glow curve shape.