Formation Dynamics of Honeycomb‐Like Capsules and Sponge‐Like Biofilms in Micrococcus Reveal a Novel Heavy Metal Avoidance Strategy

By using atomic force microscope (AFM), the topography and function of the plasmalemma surface of the isolated protoplasts from winter wheat mesophyll cells were observed, and compared with dead protoplasts induced by dehydrating stress. The observational results revealed that the plasma membrane of living protoplasts was in a state of polarization. Lipid layers of different cells and membrane areas exhibited distinct active states. The surfaces of plasma membranes were unequal, and were characterized of regionalisation. In addition, lattice structures were visualized in some regions of the membrane surface. These typical structures were assumed to be lipid molecular complexes, which were measured to be 15.8+/-0.09 nm in diameter and 1.9+/-0.3 nm in height. Both two-dimensional and three-dimensional imaging showed that the plasmalemma surfaces of winter wheat protoplasts were covered with numerous protruding particles. In order to determine the chemical nature of the protruding particles, living protoplasts were treated by proteolytic enzyme. Under the effect of enzyme, large particles became relatively looser, resulting that their width was increased and their height decreased. The results demonstrated that these particles were likely to be of protein nature. These protein particles at plasmalemma surface were different in size and unequal in distribution. The diameter of large protein particles ranged from 200 to 440 nm, with a central micropore, and the apparent height of them was found to vary from 12 to 40 nm. The diameter of mid-sized protein particles was between 40-60 nm, and a range of 1.8-5 nm was given for the apparent height of them. As for small protein particles, obtained values were 12-40 nm for their diameter and 0.7-2.2 nm for height. Some invaginated pits were also observed at the plasma membrane. They were formed by the endocytosis of protoplast. Distribution density of them at plasmalemma was about 16 pits per 15 microm(2). According to their size, we classified the invaginated pits into two types--larger pits measuring 139 nm in diameter and 7.2 nm in depth, and smaller pits measuring 96 nm in diameter and 2.3 nm in depth. On dehydration-induced dead protoplasts, the degree of polarization of plasma membranes decreased. Lipid molecular layers appeared relatively smooth, and the quantity of integral proteins reduced a lot. Invaginated pits were still detectable at the membrane surface, but due to dehydration-induced protoplast contraction, the orifice diameter of pits reduced, and their depth increased. Larger pits averagely measuring 47.4 nm in diameter and 31.9 nm in depth, and smaller pits measuring 26.5 nm in diameter and 43 nm in depth at average. The measured thickness of plasma membranes of mesophyll cells from winter wheat examined by AFM was 6.6-9.8 nm, thicker in regions covered with proteins.

Formation processes of zinc-oxide nanoparticles by ion implantation combined with thermal oxidation

Atomic force microscopy of fibrin networks and plasma clots during fibrinolysis

Among heavy metals, lead (Pb) is a non-essential metal having a higher toxicity and without any crucial known biological functions. Being widespread, non-biodegradable and persistent in every sphere of soil, air and water, Pb is responsible for severe health and environmental issues, which need appropriate remediation measures. However, microbes inhabiting Pb-contaminated area are found to have evolved distinctive mechanisms to successfully thrive in the Pb-contaminated environment without exhibiting any negative effects on their growth and metabolism. The defensive strategies used by bacteria to ameliorate the toxic effects of lead comprise biosorption, efflux, production of metal chelators like siderophores and metallothioneins and synthesis of exopolysaccharides, extracellular sequestration and intracellular bioaccumulation. Lead remediation technologies by employing microbes may appear as potential advantageous alternatives to the conventional physical and chemical means due to specificity, suitability for applying in situ condition and feasibility to upgrade by genetic engineering. Developing strategies by designing transgenic bacterial strain having specific metal binding properties and metal chelating proteins or higher metal adsorption ability and using bacterial activity such as incorporating plant growth-promoting rhizobacteria for improved Pb resistance, exopolysaccharide and siderophores and metallothionein-mediated immobilization may prove highly effective for formulating bioremediation vis-a-vis phytoremediation strategies.

The biosphere pollution with the heavy metals (HM) has increased significantly in recent decades due to human activity. Plants can accumulate and concentrate HM, which negatively affects their growth, productivity and quality of agricultural products. Some HM, such as copper, belong to the group of biogenic elements that, in low concentrations, are essential for the normal functioning of plant organisms. Other HM such as cadmium are toxic even in low concentrations. The toxicity of HM is related to oxidative damage. In the plant cell, the antioxidant system provides protection against this kind of stress. However, data on changes in antioxidant enzyme activities in the early stage of the cellular response to HM-induced stress remain scarce. Therefore, we focused our research on studying peroxidase (POD) activity changes in Arabidopsis thaliana under conditions of rapid uptake of copper and cadmium ions into leaf tissue. For the experiments, 4.5–5-week-old A. thaliana plants were used. The plants were incubated on 0.5x MS liquid medium containing copper or cadmium chloride at concentrations of 0.1, 0.5 and 5 mM. The HM salt treatment was carried out in the dark at 20 °C for 2 (short-term stress) and 12 (long-term stress) hours. After that, the leaves were frozen and the POD activity was measured. Evaluation of the effects of Cd2+ and Cu2+ ions shows that these HM cause a decrease in POD activity after 2 hours and its increase after 12 hours of treatment. Therefore, modulation of POD activity is a component of the HM stress response in A. thaliana. Analysis of the available data revealed that the enzymes POD and CAT, which eliminate hydrogen peroxide, can partially replace each other and thus provide cellular protection in different phases of the stress response.

Iron plaque formation and heavy metal uptake in Spartina alterniflora at different tidal levels and waterlogging conditions

Site selective growth of Ge quantum dots on AFM-patterned Si substrates

This study deals with the determination of the relative abundance of the oxide layer in the near-surface volume of aluminum nanoparticles of 50-100 nm in diameter. They are bombarded with a sequence of single projectiles of Au 400(4+) accelerated to 136 keV. The ionized ejecta from each impact are recorded individually which allows identification of ions emitted from a surface volume of approximately 10 nm in diameter and 5-10 nm in depth. The mode of analyzing ejecta individually from each single cluster impact is a means to apply mass spectrometry in nanovolumes.

Two micro processing techniques based on scanning probe microscopy (SPM) are described. One is electrochemical etching and deposition using a scanning tunneling microscope (STM). STM is very useful tool of nm-scaled observation, and it can be also used as precise positioner in micro processing. In micro electrochemical processing system, a potentiostat for processing is externally attached to STM system, a STM probe was set very closely to a metal substrate in electrolyte solution, and voltage was applied between the substrate and the probe. Then electrochemical reaction occurs in restricted area of the substrate. Therefore, micrometer-size structures are produced by faradic current. A line pattern, which is 200-300 nm in width and 100 nm in depth, was electrochemically etched. When polarity of applied voltage was inverted, a bump pattern, 300 nm in diameter, 200 nm in height, was electrochemically deposited. Another processing method is using a scanning near-field optic/atomic force microscope (SNOAM). The SNOAM provides simultaneous topographic and optical images with high resolution beyond the diffraction limit, better than 100 nm. The optical processing is demonstrated in the photoresist film by the SNOAM. We obtained pit and line patterns down to 100 nm in diameter and width, respectively.

Adsorption of copper by canola meal

Heavy metal removal by biomineralization of urease producing bacteria isolated from soil

Introduction: Spindles are microtubules-based machines whose primary function is to accurately segregate chromosomes in both mitotic and meiotic cell division. The structure of spindles is critical for their function; errors in morphology or attachment to chromosomes lead to aneuploidy, potentially resulting in disease, infertility, and lethality. Electron microscopy studies have yielded fine-detail spindle ultrastructures in many plant and animal species, but no studies have investigated the spindle of Zea mays, a critical crop, and cytogenetic model system. Methods: Here we use electron tomography (ET), reconstruction, and modeling to obtain three-dimensional, nanometer-resolution of the Z. mays meiotic spindle. Structures such as microtubules, kinetochores, vesicles, membrane channels, and nuclear envelope were modeled through a partial spindle reconstruction, and confirmed using immunostaining and live fluorescence microscopy. Results: ET revealed that maize spindles contain 8–18 kinetochore microtubules (kMTs) per kinetochore, which are approximately 776 nm in diameter and 316 nm in depth. Small ∼37 nm vesicles were identified, as well as larger (∼5 µm long, 800 nm wide) membrane structures with channels that allow spindle microtubules to pass through. These membrane channels stain positively for the ER-marker protein disulfide isomerase. Imaging of prophase meiotic cells revealed a cross-hatch microtubule arrangement in the perinuclear ring on the external surface of the nuclear envelope, which also contained type II nuclear grooves with transnuclear microtubules passing from the nucleus to the cytoplasm. Conclusions: Z. mays meiotic spindles are similar to animal counterparts with a comparable number of kMTs and pre-spindle transnuclear microtubules but also plant-specific features such as Golgi-derived vesicles to assist cell plate formation, internal ER membrane channels, and a perinuclear microtubule ring that aids spindle assembly. Maize kinetochores have an electron-diffuse ball in cup morphology that is comparable in size to Drosophila kinetochores and larger than mammalian kinetochores.

Research on heavy metals (iron and copper) ions uptake in wastewater using papaya seed powder has been conducted. The purpose of this study was to provide solutions on handling and processing of heavy metal waste in the laboratory. The adsorption method is used for this purpose. Activation of the adsorbent was carried out to determine the effectiveness of the unactivated and activated adsorbents.Activation is done using a neutral activator (aquadest). Papaya seed as the adsorbent agent (both un-activated and activated ones) was used in four mass variations in order to determine the optimum mass of papaya seed powder to absorb the heavy metals. The results show that the optimum adsorbent mass was 2 grams for both metal ions (iron and copper). The activated adsorbent is more effective in the adsorption process. The adsorption efficiency of iron (Fe) metal ions in wastewater was 58.80%, the adsorption capacity value was 257.10 mg/g. While the adsorption efficiency of copper (Cu) metal ions in wastewater was 90.70%, the adsorption capacity value was 345.04mg/g.

The uptake of copper ion by several green microalgae was investigated. The copper tolerance differed with different species of the green microalgae and Chlamydomonas angulosa was the most copper tolerant green microalga. The amounts of copper taken up by the green microalgae rapidly increased in the first 0.5_??_2 hr and then gradually increased with the passage of time. The amount of copper taken up slightly differed with different species of green microalgae. The relationship between the copper tolerance of the green microalgae and their copper uptake could be classified into four groups: 1) copper tolerant algae which take up large amount of copper, 2) copper tolerant algae which take up small amount of copper, 3) copper sensitive algae which take up large amount of copper, and 4) copper tolerant algae which take up small amount of copper. The amount of potassium in the algal cells rapidly decreased in the first 1_??_2 hr after copper supplying and then gradually increased. The ratios of cupric ion obtained from ESR measurements to the copper amounts from the neutron activation analysis differed with different species of green microalgae. We assumed that some part of cupric ion taken up by green microalgae was reduced to cuprous ion mediated by a metabolic process. About 35_??_83% of copper taken up by green microalgae was released by EDTA washing. For the copper tolerant green microalgae the ratio of copper eluted by EDTA washing was larger than that for the copper sensitive green microalgae. For the green microalgae which took up a large amount of copper the amount of copper eluted by EDTA washing was also large. The distribution of copper differed with different species of green microalgae.

The effect of plant growth-promoting bacteria inoculation on Helianthus annuus growth and copper (Cu) uptake was investigated. For this, the strains CC22, CC24, CC30, and CC33 previously isolated from heavy metal- and hydrocarbon-polluted soil were selected for study. These strains were characterized on the basis of their 16S rDNA sequences and identified as Pseudomonas putida CC22, Enterobacter sakazakii CC24, Acinetobacter sp. CC30, and Acinetobacter sp. CC33. Strains were able to synthesize indole, solubilize phosphorus, and produce siderophores in vitro, which are proper characteristics of plant growth-promoting (PGP) bacteria. Bacteria were also able to bioaccumulate Cu(II), and most of them could use aromatic hydrocarbons as a sole carbon source. Furthermore, Acinetobacter sp. CC33 exhibited the greatest extent of Cu(II) accumulation, and CC30 the widest range for degrading hydrocarbons. Acinetobacter sp. CC30 was selected for pot experiments on the basis of its plant growth-promoting properties. Inoculation with CC30 significantly increased the plant biomass (dry weight and length of root and shoot) and improved the photosynthetic pigment content in non- and Cu-contaminated soil (p < 0.05). Additionally, plant Cu uptake was improved by CC30 inoculation showing a significantly enhanced root Cu content (p < 0.05). Our findings evidenced that the strain CC30 protected the plant against the deleterious effect of Cu contamination and improved the Cu extraction by plant, hence concluding that its inoculation represents an alternative to improve phytoremediation process of heavy metals, particularly Cu, in contaminated environments.