MV-mimicking micelles loaded with PEG-serine-ACP nanoparticles to achieve biomimetic intra/extra fibrillar mineralization of collagen in vitro

Since their discovery, matrix vesicles (MVs) containing minerals have received considerable attention for their role in the mineralization of bone, dentin and calcified cartilage. Additionally, MVs' association with collagen fibrils, which serve as the scaffold for calcification in the organic matrix, has been repeatedly highlighted. The primary purpose of the present study was to establish a MVs–mimicking model (PEG-S-ACP/micelle) in vitro for studying the exact mechanism of MVs-mediated extra/intra fibrillar mineralization of collagen in vivo. In this study, high-concentration serine was used to stabilize the amorphous calcium phosphate (S-ACP), which was subsequently mixed with polyethylene glycol (PEG) to form PEG-S-ACP nanoparticles. The nanoparticles were loaded in the polysorbate 80 micelle through a micelle self-assembly process in an aqueous environment. This MVs–mimicking model is referred to as the PEG-S-ACP/micelle model. By adjusting the pH and surface tension of the PEG-S-ACP/micelle, two forms of minerals (crystalline mineral nodules and ACP nanoparticles) were released to achieve the extrafibrillar and intrafibrillar mineralization, respectively. This in vitro mineralization process reproduced the mineral nodules mediating in vivo extrafibrillar mineralization and provided key insights into a possible mechanism of biomineralization by which in vivo intrafibrillar mineralization could be induced by ACP nanoparticles released from MVs. Also, the PEG-S-ACP/micelle model provides a promising methodology to prepare mineralized collagen scaffolds for repairing bone defects in bone tissue engineering.     

Optimization of the demineralization process for the extraction of chitin from Omani Portunidae segnis

Chitin is an organic polymer and it is the most frequent marine natural polysaccharide after cellulose. The main natural sources of chitin are exoskeletons of insects, mollusks, the cell walls of certain fungi and crustaceans such as crabs, shrimps and lobsters. The waste of these marine exoskeletons are pollutant for the environment, but these waste raw materials could be useful for production of commercial products like chitin. Chitin is an important raw material used for water treatment, agricultural, biomedical, biotechnological purposes, food and paper industry and cosmetics. Based on the variety of importance, the present targets of this study are to optimize the demineralization process for the removal of calcium and phosphate contents from the waste of Portunidae segnis (P. segnis) by using acid at ambient temperature and to characterize the isolated demineralized sample as well as the percentage of remaining calcium and phosphorus contents by using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). The prepared waste carbs coarse powder samples of P. segnis were demineralized with seven different concentrations of hydrochloric acid at ambient temperature for 1 h. All the demineralization samples by the different concentrations were analyzed by using sensitive ICP-OES. The results based on ICP-OES showed that among the seven different concentrations used in the demineralization process for the isolation of chitin, the best was 2 M of HCl concentration for the production of chitin. The results also showed that the optimized concentration 2 M HCl gave the minimum concentration of calcium and phosphorus compared to other concentrations applied in this experiment. In conclusion, the optimized concentration for demineralization process could be used commercially for the isolation or commercial production of chitin for agricultural, biomedical and biotechnological purposes.     

Determination of titanium dioxide supplements in different matrices using two methods involving photometer and inductively coupled plasma optical emission spectrometer measurements

Titanium dioxide (TiO₂) is a viable marker in digestibility studies using different animal species. The photometrical analysis is based on an intense orange colour following the addition of hydrogen peroxide to an acid solution. The measurement using inductively coupled plasma optical emission spectrometry (ICP-OES) is a method for analysing more than one element from the same sample preparation. The present study was conducted to investigate whether an established ICP-OES element analysis following acid-based hydrolysis is appropriate for titanium analysis. Defined amounts of TiO₂ were added to samples obtained in studies with cows, pigs and turkeys and recoveries were determined. It was shown that supplemented TiO₂ can be determined in samples of feeds, faeces or excreta, and digesta using a method based on photometric or ICP-OES measurement. The differences between the true and measured titanium concentrations indicate that using the ICP-OES method leads to a higher accuracy of determination.     

Distribution of toxic elements between biotic and abiotic components of terrestrial ecosystem along an urbanization gradient: Soil,leaf litter and ground beetles

Urbanization and anthropogenic activities are the major source of environmental pollution which may cause damage in terrestrial ecosystems and their organisms. Toxic elements can accumulate in soil and leave tissue; thus, through the food chain they can accumulate in predatory organisms. The aim of our study was to investigate the effects of urbanization on toxic element concentration in soil, leaf litter and Carabus violaceus and Pterostichus oblongopunctatus specimens along an urbanization gradient. The studied predator species were common and their distribution is widespread along the urbanization gradient. Soil, leaf litter and ground beetles were collected from three forested area: urban park, suburban forest and rural forest. The following toxic element concentrations were analyzed in all samples: Al, Ba, Cd, Cu, Fe, Mn, Ni, Pb, Sr and Zn. In the soil there was no significant difference in toxic element concentration between areas, except in seasons. Significantly higher toxic element concentration was found in autumn than in spring in the soil. In the case of leaf litter we found significant differences between areas in the following toxic elements: Ba, Cu, Mn, Sr and Zn. The concentrations of all elements were significantly higher in autumn than in spring. Significantly higher concentration was found in P. oblongopunctatus specimens than in C. violaceus for all studied elements, except Sr. We found significant differences in elemental concentrations between sexes in both species. Significantly higher Cu and Pb concentration was found in male beetles than in female ones. Just the opposite was true for the Sr concentration. We found positive correlation between toxic element concentration of C. violaceus and leaf litter for Mn and Zn. Negative correlations were found between toxic elements of ground beetles and soil for Al, Ba, Fe, Sr and Zn. Our study confirms that different breeding strategies and sexes cause differences in the accumulation of toxic elements. In summary, we demonstrated that ground beetles, leaf litter and soil were suitable bioindicators for monitoring the effects of urbanization and anthropogenic activities on terrestrial ecosystem.     

Essential Elements as a Distinguishing Factor between Mycorrhizal Potentials of Two Cohabiting Truffle Species in Riparian Forest Habitat in Serbia

True truffles (Tuber sp.) that establish ectomycorrhizal symbiosis (ECM) with trees in the Mediterranean and temporal regions have species specific abilities to assimilate soil born elements. Suitable habitats are usually inhabited by few truffle species, while distinguishing their symbiotic potentials appeared very difficult. Two species that commonly inhabit riparian forests in Serbia are the most prized one, Tuber magnatum Pico (Piedmont white truffle) and not so highly valued Tuber brumale Vitt . In order to assess potential differences between their assimilation and accumulation abilities, the differences between contents of elements that may be the subjects of the symbiotic trade between the host plant and fungi were evaluated in accumulation target (ascocarps) and their source (the soil). Essential (K, Na, Ca, Mg, Fe, P, S, and Zn) and essential trace elements (Co, Cr, Cu, Mn, and Se) in truffles and soil samples were determined by means of inductively coupled plasma with optical emission spectrometry (ICP‐OES). Their concentrations (mg/kg) in ascocarps were in the range from 1.364±0.591 (Cr) to 10760.862±16.058 (K), while in soil ranged from 23.035±0.010 (Cr) to 20809.300±122.934 (Fe). Element accumulation potential (bioaccumulation factor) was calculated in the system truffle/soil. The statistical approaches were used for establishing the differences, while the possible differentiation between symbiotic potentials of two mycelia in the defined soil conditions was discussed.     

Substrate specificity and evolutionary implications of a NifDK enzyme carrying NifB-co at its active site

The in vitro reconstitution of molybdenum nitrogenase was manipulated to generate a chimeric enzyme in which the active site iron-molybdenum cofactor (FeMo-co) is replaced by NifB-co. The NifDK/NifB-co enzyme was unable to reduce N₂ to NH₃, while exhibiting residual C₂H₄ and considerable H₂ production activities. Production of H₂ by NifDK/NifB-co was stimulated by N₂ and was dependent on NifH and ATP hydrolysis. Thus, NifDK/NifB-co is a useful tool to gain insights into the catalytic mechanism of nitrogenase. Furthermore, phylogenetic analysis of D and K homologs indicates that several early emerging lineages, which contain NifB, NifH and NifDK encoding genes but which lack other genes required for processing NifB-co into FeMo-co, might encode an enzyme with similar catalytic properties to NifDK/NifB-co.     

Concentration of essential and non-essential elements and carcinogenic / non-carcinogenic health risk assessment of commercial bee pollens from Turkey

BackgroundBee pollen, known as a natural super-food with valuable nutritional ingredients, is regarded as a good indicator of ecotoxic substances, such as potentially toxic elements (PTEs). Therefore, this study aims to examine the concentrations of selected PTEs (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Pb, Se, Sn, Sr, V, Zn) in bee pollen purchased from online markets in Turkey and perform a health risk assessment to identify the potential risk to consumers.MethodsThe quantitative analyses were conducted by inductively coupled plasma optical emission spectrometry (ICP-OES).ResultsThe mean values of essential PTEs in decreasing content order were Mg > Fe > Zn > Mn > Cu > Ni > Se > Cr > Mo >Co = V. Regarding the results of the study, daily consumption (40 g for adult or 20 g for children) of commercial bee pollen can recompense 20–35 % of daily Cu, Mn, Se requirements for children, adults, pregnant, and breastfeeding women. The decreasing content order of non-essential elements was Al > Sn > Sr > Ba > Pb > As. Cadmium and Hg concentrations were below the detection limits in all the samples. In terms of food and public health; detection of the PTEs concentrations is necessary to assess the quality and safety of bee pollen before consumption. According to the carcinogenic and non-carcinogenic risk assessments; commercial pollen consumption does not pose a health risk to either children or adults for the PTEs monitored in this study.ConclusionWe conclude that bee pollen is an ideal indicator for the monitoring of environmental pollution of PTEs and also a valuable source of essential elements. This study highlights the need to develop standards that regulate acceptable concentrations of PTEs.     

罗汉果微量元素的花粉直感效应研究

用ICP-OES法测定罗汉果中受花粉直感效应影响明显的微量元素含量。结果表明:两种不同授粉处理的罗汉果样品中Zn、Fe、Cr、Al四种微量元素含量差异显著,受花粉直感作用的影响较大,尤其是Zn元素;罗汉果样品铅含量超过罗汉果行标NY/T 694-2003的限量标准,但符合药用植物绿色行标WM/T 2-2004,研究认为,罗汉果行标Pb标准不太严格,有必要进一步研究和探讨;高甜苷Ⅴ授粉组合("青皮3号"×"红毛1号")果实中B元素含量较高,为硼微肥的利用提供科学依据;而低甜苷Ⅴ组合("青皮3号"×"红毛2号")果实中8种微量元素含量偏高,其中锰与提高呼吸速率有关。     

Effects of Copper Sulfate on Seedlings of Prosopis pubescens (Screwbean Mesquite)

Phytoextraction is an established method of removal of heavy metals from contaminated soils worldwide. Phytoextraction is most efficient if local plants are used in the contaminated site. We propose that Prosopis pubescens (Screw bean mesquite) would be a successful phytoextractor of copper in our local soils. In order to determine the feasibility of using Screw bean mesquite, we utilized inductively-coupled plasma-optical emission spectroscopy (ICP-OES) and elemental analysis to observe the uptake of copper and the effects on macro and micro nutrients within laboratory-grown seedlings. We have previously shown that P. pubescens is a hyperaccumulator of copper in soil-grown seedlings.

Light and transmission electron microscopy demonstrated death of root cells and ultrastructural changes due to the presence of copper from 50 mg/L – 600 mg/L. Ultrastructural changes included plasmolysis, starch accumulation, increased vacuolation and swollen chloroplasts with disarranged thylakoid membranes in cotyledons. Inductively coupled plasma-optical emission spectroscopy analyses of macro- and micro-nutrients revealed that the presence of copper sulfate in the growth medium of Petri-dish grown Prosopis pubescens seedlings resulted in dramatic decreases of magnesium, potassium and phosphorus. At 500-600 mg/L of copper sulfate, a substantial increase of sulfur was present in roots.     

Application of Synchrotron Radiation X-Ray Fluorescence (μ-SRXF) and X-Ray Microanalysis (SEM/EDX) for the Quantitative and Qualitative Evaluation of Trace Element Accumulation in Woody Plants

Different analytical techniques were applied to describe the localization of lead and chromium in the tissues of walnut (Juglans regia) and maple (Acer saccharinum) plants exposed to soils that had been artificially contaminated with heavy metals. Two X-ray-based techniques, synchrotron radiation X-ray fluorescence (μ-SRXF) and X-ray microanalysis (SEM/EDX), were utilized in association with induced coupled plasma optical emission spectrometry (ICP-OES). These techniques allowed the definition of maps showing a preferential accumulation of lead in the root periderm of both plants and a limited translocation of the metal to the stems. Accordingly, estimation of the lead concentration with ICP-OES showed that roots contained, on a dry weight basis, 20 to 40 times more metal than stems. Chromium, supplied to the plants as Cr³⁺ or Cr⁶⁺, was taken up only in the latter case and in limited amounts. In general, walnut was more efficient than maple in the uptake of lead and chromium. The combination of X-ray-based techniques and ICP-OES proved to be a powerful quantitative tool in mapping, with high definition, the sites of metal storage in plant tissues.