Incorporation of Barium Ions into Biomaterials: Dangerous Liaison or Potential Revolution?

In the present manuscript, a brief overview on barium, its possible utilization, and the aftermath of its behavior in organisms has been presented. As a bivalent cation, barium has the potential to be used in a myriad of biochemical reactions. A number of studies have exhibited both the unwanted outcome barium displayed and the advantages of barium laden compounds, tested in in vitro and in vivo settings. The plethora of prospective manipulations covered the area of hydrogels and calcium phosphates, with an end goal of examining barium’s future in the tissue engineering. However, majority of data revert to the research conducted in the 20th century, without investigating the mechanisms of action using current state-of-the-art technology. Having this in mind, set of questions that are needed for possible future research arose. Can barium be used as a substitute for other biologically relevant divalent cations? Will the incorporation of barium ions hamper the execution of the essential processes in the organism? Most importantly, can the benefits outweigh the harm?

Chloroplastic SaNADP-ME4 of C3–C4 Woody Desert Species Salsola laricifolia Confers Drought and Salt Stress Resistance to Arabidopsis

The NADP-malic enzyme (NADP-ME) catalyzes the reversible decarboxylation of L-malate to produce pyruvate, CO2, and NADPH in the presence of a bivalent cation. In addition, this enzyme plays crucial roles in plant developmental and environment responses, especially for the plastidic isoform. However, this isoform is less studied in C3–C4 intermediate species under drought and salt stresses than in C3 and C4 species. In the present study, we characterized SaNADP-ME4 from the intermediate woody desert species Salsola laricifolia. SaNADP-ME4 encoded a protein of 646 amino acids, which was found to be located in the chloroplasts based on confocal imaging. Quantitative real-time PCR analysis showed that SaNADP-ME4 was highly expressed in leaves, followed by stems and roots, and SaNADP-ME4 expression was improved and reached its maximum under the 200 mm mannitol and 100 mm NaCl treatments, respectively. Arabidopsis overexpressing SaNADP-ME4 showed increased root length and fresh weight under mannitol and salt stress conditions at the seedling stage. In the adult stage, SaNADP-ME4 could alleviate the decreased in chlorophyll contents and PSII photochemical efficiency, as well as improve the expression of superoxide dismutase, peroxidase, and pyrroline-5-carboxylate synthase genes to enhance reactive oxygen species scavenging capability and proline levels. Our results suggest that SaNADP-ME4 overexpression in Arabidopsis increases drought and salt stress resistance.

Transport, functions, and interaction of calcium and manganese in plant organellar compartments

Calcium (Ca2+) and manganese (Mn2+) are essential elements for plants and have similar ionic radii and binding coordination. They are assigned specific functions within organelles, but share many transport mechanisms to cross organellar membranes. Despite their points of interaction, those elements are usually investigated and reviewed separately. This review takes them out of this isolation. It highlights our current mechanistic understanding and points to open questions of their functions, their transport, and their interplay in the endoplasmic reticulum (ER), vesicular compartments [Golgi apparatus, trans-Golgi Network (TGN), prevacuolar compartment (PVC)], vacuoles, chloroplasts, mitochondria, and peroxisomes. Complex processes demanding these cations, such as Mn2+-dependent glycosylation or systemic Ca2+ signaling, are covered in some detail if they have not been reviewed recently or if recent findings add to current models. The function of Ca2+ as signaling agent released from organelles into the cytosol and within the organelles themselves is a recurrent theme of this review, again keeping the interference by Mn2+ in mind. The involvement of organellar channels [e.g., Glutamate-Receptor-Likes (GLRs), Cyclic-Nucleotide-Gated Channels (CNGCs), Mitochondrial Conductivity Units (MCUs), Two-Pore Channel1 (TPC1)], transporters [e.g., Natural-Resistance-Associated Macrophage Proteins (NRAMPs), Calcium Exchangers (CAXs), Metal-Tolerance Proteins (MTPs), Bivalent-Cation Transporters (BICATs)] and pumps [Autoinhibited Ca2+-ATPases (ACAs), ER Ca2+-ATPases (ECAs)] in the import and export of organellar Ca2+ and Mn2+ is scrutinized, whereby current controversial issues are pointed out. Mechanisms in animals and yeast are taken into account where they may provide a blueprint for processes in plants, in particular with respect to tunable molecular mechanisms of Ca2+-versus-Mn2+ selectivity.

Bacterial Toxicity Testing: Modification and Evaluation of the Luminescent Bacteria Test and the Respiration Inhibition Test

The activated sludge respiration inhibition test and the luminescent bacteria test with Vibrio fischeri are important bacterial test systems for evaluation of the toxicity of chemical compounds. These test systems were further optimized to result in better handling, reliability and sensitivity. Concerning the Vibrio fischeri test, media components such as yeast extract and bivalent cation concentrations like Ca2+ and Mg2+ were optimized. The cultivation, storage conditions and reactivation process of the stored bacteria were also improved, which enabled simpler handling and led to good reproducibility. Additionally, the respiration inhibition test with a prolonged incubation time was further analyzed using different chlorinated phenols as reference compounds. It could be stated that a longer incubation period significantly improved the sensitivity of the test system.

TEMPO-Nanocellulose/Ca2+ Hydrogels: Ibuprofen Drug Diffusion and In Vitro Cytocompatibility

Stable hydrogels with tunable rheological properties were prepared by adding Ca2+ ions to aqueous dispersions of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)-oxidized and ultra-sonicated cellulose nanofibers (TOUS-CNFs). The gelation occurred by interaction among polyvalent cations and the carboxylic units introduced on TOUS-CNFs during the oxidation process. Both dynamic viscosity values and pseudoplastic rheological behaviour increased by increasing the Ca2+ concentration, confirming the cross-linking action of the bivalent cation. The hydrogels were proved to be suitable controlled release systems by measuring the diffusion coefficient of a drug model (ibuprofen, IB) by high-resolution magic angle spinning (HR-MAS) nuclear magnetic resonance (NMR) spectroscopy. IB was used both as free molecule and as a 1:1 pre-formed complex with β-cyclodextrin (IB/β-CD), showing in this latter case a lower diffusion coefficient. Finally, the cytocompatibility of the TOUS-CNFs/Ca2+ hydrogels was demonstrated in vitro by indirect and direct tests conducted on a L929 murine fibroblast cell line, achieving a percentage number of viable cells after 7 days higher than 70%.

Influence of physicochemical properties of the soil solution on the 226Ra distribution coefficient in soils

Defined as the ratio between the isotope’s activity concentrations in the solid fraction of the soil and in the soil solution, the distribution coefficient (Kd) of 226Ra is an equilibrium constant that encompasses all the interface processes that comprise its sorption as a whole. However, there is a great variability in the reported measured values of radium Kd. A first classification of soils in terms of their texture reduces this variability somewhat, but the chemical environment of the soil solution is also expected to exert a significant influence on the sorption process and therefore on the Kd. In the present work, linear regressions are applied to look for relationships between the radium Kd and the physicochemical properties of the soil solution. The soil solutions were studied of three soils with different textural characteristics but taken from the same natural soil. For the soil classified as loamy coarse sand, the significant independent variables affecting Kd were the pH, conductivity, and dissolved organic matter; for the soil classified as loamy fine sand, they were the bivalent cation concentration and pH; and for the soil classified as loam, they were the conductivity and nitrate concentration.

Development of coagulant synthesis byproducts from cengar clay as adsorbent in post-coagulation peat water treatment

Cengar clay was used as a precursor for liquid coagulant and adsorbent. It was calcined at 700°C for 1 hour followed by extracting with 0.2 moles H2SO4 at 80 and 100°C for 2 hours respectively. The main products are liquid coagulant of LC1(80-2) and LC1(100-2) which applied to coagulate the peat water. The liquid coagulants were characterized for pH and cation contents. And then after coagulation, peat water were adsorbed by using each extraction byproducts of liquid coagulant include LCA1(80-2) and LCA1(100-2) having adsorbent-peat water ratio 0.5:100 and 1:100 (w/v). Minerals characteristic of adsorbents were characterized using X-ray diffraction method. The several peat water parameters were analyzed for pH, color, turbidity, and organic substances. The results achieved that liquid coagulants were containing bivalent cation (Ca and Mg) far more than trivalent cation (Al and Fe) and pH 7-8. On the other hand, the adsorbent has found of kaolinite, montmorillonite, muscovite and calcite minerals. The liquid coagulant has not been able to improve the overall parameters analyzed. However, the LC1(80-2) coagulant achieved only removal efficiency of color 12.47%, turbidity 17.59% and organic substances 2.55% respectively. Meanwhile, the most effective adsorbent for post-coagulation peat water was achieved by LCA1(80-2) on 1:100 ratio that increases the water pH becomes neutral, removal efficiency of color 96.57%, turbidity 98.03% and organic substances 81.55%, respectively. Therefore, the adsorbent performance is much better than the coagulant in peat water treatment. As a conclusion, the adsorption step can cope up with the bad condition of post-coagulation of peat water.