Strength and Leaching Characteristics of Magnesium Phosphate Cement-Solidified Zinc- Contaminated Soil under the Effect of Acid Rain

Long-term static leaching experiments were conducted to investigate characteristics of magnesium phosphate cement (MPC) solidified/stabilized Zn-contaminated soil under impact of acid rain. Effects of initial pH values of acid rain, binder agent types and compositions, as well as curing age on strength and leaching characteristics of the sample were analyzed. Standard sand was used as raw material, with the content of cement at 15%. Our study used two types of MPC with MgO/KH₂PO₄(M/P) ratio of 3:1 and 6:1 (respectively referred to as M3 and M6), and also ordinary Portland cement with content at 15% (referred to as C15) as test control. Experimental results show that acid rain with pH = 2 has the greatest weakening effect on unconfined compressive strength (q_u) of the sample, while with pH = 4 and 7 such weakening effects on q_u are similar. Research findings also indicate that M6 is the most effective in immobilizing Zn-spiked soils, M3 is next and C15 is the least. The effect of Zn²⁺ on hydration of MPC is much lower than that of C15. Precuring method can improve q_u of the MPC-solidified samples and its resistance to acid rain. Compared with non-renewal, replacing acid rain leachant at designated intervals decreases q_u of the sample.     

Glutamine-Fructose-6-Phosphate Transaminase 2 (GFPT2) Is Upregulated in Breast Epithelial–Mesenchymal Transition and Responds to Oxidative Stress

Breast cancer cells that have undergone partial epithelial–mesenchymal transition (EMT) are believed to be more invasive than cells that have completed EMT. To study metabolic reprogramming in different mesenchymal states, we analyzed protein expression following EMT in the breast epithelial cell model D492 with single-shot LFQ supported by a SILAC proteomics approach. The D492 EMT cell model contains three cell lines: the epithelial D492 cells, the mesenchymal D492M cells, and a partial mesenchymal, tumorigenic variant of D492 that overexpresses the oncogene HER2. The analysis classified the D492 and D492M cells as basal-like and D492HER2 as claudin-low. Comparative analysis of D492 and D492M to tumorigenic D492HER2 differentiated metabolic markers of migration from those of invasion. Glutamine-fructose-6-phosphate transaminase 2 (GFPT2) was one of the top dysregulated enzymes in D492HER2. Gene expression analysis of the cancer genome atlas showed that GFPT2 expression was a characteristic of claudin-low breast cancer. siRNA-mediated knockdown of GFPT2 influenced the EMT marker vimentin and both cell growth and invasion in vitro and was accompanied by lowered metabolic flux through the hexosamine biosynthesis pathway (HBP). Knockdown of GFPT2 decreased cystathionine and sulfide:quinone oxidoreductase (SQOR) in the transsulfuration pathway that regulates H₂S production and mitochondrial homeostasis. Moreover, GFPT2 was within the regulation network of insulin and EGF, and its expression was regulated by reduced glutathione (GSH) and suppressed by the oxidative stress regulator GSK3-β. Our results demonstrate that GFPT2 controls growth and invasion in the D492 EMT model, is a marker for oxidative stress, and associated with poor prognosis in claudin-low breast cancer.     

Structural and functional changes in a synthetic S5 segment of KvLQT1 channel as a result of a conserved amino acid substitution that occurs in LQT1 syndrome of human

Mutations in various voltage gated cardiac ion channels are the cause of different forms of long QT syndrome (LQTS), which is an inherited arrhythmic disorder marked as a prolonged QT interval on electrocardiogram. Of these LQTS1 is associated with mutations in the gene encoding KCNQ1 (KvLQT1) channel. One responsible mutation, G269S, in the S5 segment of KvLQT1, that affects the proper expression and function of channel protein leads to LQTS1. Our objective was to study how G269S mutation interferes with the structure and function of a synthetic S5 segment of KvLQT1 channel. One wild type 22-residue peptide and another mutant peptide of the same length with G269S mutation, derived from the S5 segment were synthesized and labeled with fluorescent probes. The mutant peptide exhibited lower affinity towards phospholipid vesicles as compared to the wild type peptide and showed impaired assembly and localization onto the lipid vesicles as evidenced by membrane-binding, energy transfer and proteolytic cleavage experiments. Loss in the helical content of S5 mutant peptide in membrane-mimetic environments was observed. Furthermore, it was observed that G269S mutation significantly inhibited the ability of S5 peptide to permeabilize the lipid vesicles. The present studies show the basis of change in function of the selected S5 segment as a result of G269S mutation which is associated with LQT1 syndrome. We speculate that the structural and functional changes related to the glycine to serine amino acid substitution in the S5 segment may also influence the activity of the whole KvLQT1 channel.     

Phosphogenesis in the 2460 and 2728 million‐year‐old banded iron formations as evidence for biological cycling of phosphate in the early biosphere

The banded iron formation deposited during the first 2 billion years of Earth's history holds the key to understanding the interplay between the geosphere and the early biosphere at large geological timescales. The earliest ore‐scale phosphorite depositions formed almost at ~2.0–2.2 billion years ago bear evidence for the earliest bloom of aerobic life. The cycling of nutrient phosphorus and how it constrained primary productivity in the anaerobic world of Archean–Palaeoproterozoic eons are still open questions. The controversy centers about whether the precipitation of ultrafine ferric oxyhydroxide due to the microbial Fe(II) oxidation in oceans earlier than 1.9 billion years substantially sequestrated phosphate, and whether this process significantly limited the primary productivity of the early biosphere. In this study, we report apatite radial flowers of a few micrometers in the 2728 million‐year‐old Abitibi banded iron formation and the 2460 million‐year‐old Kuruman banded iron formation and their similarities to those in the 535 million‐year‐old Lower Cambrian phosphorite. The lithology of the 535 Million‐year‐old phosphorite as a biosignature bears abundant biomarkers that reveal the possible similar biogeochemical cycling of phosphorus in the Later Archean and Palaeoproterozoic oceans. These apatite radial flowers represent the primary precipitation of phosphate derived from the phytoplankton blooms in the euphotic zones of Neoarchean and Palaoeproterozoic oceans. The unbiased distributions of the apatite radial flowers within sub‐millimeter bands do not support the idea of an Archean Crisis of Phosphate. This is the first report of the microbial mediated mineralization of phosphorus before the Great Oxidation Event when the whole biosphere was still dominated by anaerobic microorganisms.     

Microbial solubilization of rock phosphate on media containing agro-industrial wastes and effect of the resulting products on plant growth and P uptake

Four agro-industrial wastes were assayed as substrates for microbial solubilization of rock phosphate (RP). Sugar beet wastes (SB), olive cake (OC) and olive mill wastewaters (OMWW) were treated by Aspergillus niger, and dry olive cake (DOC) was treated by Phanerochaete chrysosporium. In conditions of solid-state fermentation 46% of SB and 21% of OC were mineralized by A. niger while 16% of DOC was mineralized by P. chrysosporium. Repeated-batch mode of fermentation was employed for treatment of OMWW by immobilized A. niger, which resulted in conversion of 80% of the fermentable sugars. Acidification of all media treated by A. niger was registered with a simultaneous solubilization of 59.7% (SB), 42.6% (OC), and 36.4% (OMWW) of the total P present in the RP. The same mechanism of RP solubilization was observed in DOC-based medium inoculated with P. chrysosporium but other mechanisms were probably involved during the process. A series of microcosm experiments were then performed in the greenhouse to evaluate the effectiveness of the resulting fermented products. All amendments improved plant growth and P acquisition, which were further enhanced by mycorrhizal inoculation. The level of all studied parameters including the root mycorrhizal colonization depended on the substrate characteristics. The reported biotechnological schemes offer a potential application particularly for degraded soils.     

An S-glutathiomimetic Provides Structural Insights into Stromal Interaction Molecule-1 Regulation

Stromal interaction molecule 1 (STIM1) is an endo/sarcoplasmic reticulum (ER/SR) calcium (Ca²⁺) sensing protein that regulates store-operated calcium entry (SOCE). In SOCE, STIM1 activates Orai1-composed Ca²⁺ channels in the plasma membrane (PM) after ER stored Ca²⁺ depletion. S-Glutathionylation of STIM1 at Cys56 evokes constitutive SOCE in DT40 cells; however, the structural and biophysical mechanisms underlying the regulation of STIM1 by this modification are poorly defined. By establishing a protocol for site-specific STIM1 S-glutathionylation using reduced glutathione and diamide, we have revealed that modification of STIM1 at either Cys49 or Cys56 induces thermodynamic destabilization and conformational changes that result in increased solvent-exposed hydrophobicity. Further, S-glutathionylation or point-mutation of Cys56 reduces Ca²⁺ binding affinity, as measured by intrinsic fluorescence and far-UV circular dichroism spectroscopies. Solution NMR showed S-glutathionylated-induced perturbations in STIM1 are localized to the α1 helix of the canonical EF-hand, the α3 and α4 helices of the non-canonical EF-hand and α6 and α8 helices of the SAM domain. Finally, we designed an S-glutathiomimetic mutation that strongly recapitulates the structural, biophysical and functional effects within the STIM1 luminal domain and we envision to be another tool for understanding the effects of protein S-glutathionylation in vitro, in cellulo and in vivo.     

Degradation of glycerol using hydrothermal process

Sub-critical or supercritical water was utilized for the degradation of glycerol in an environmentally benign reaction. The reaction was carried out in a batch reactor in the temperature range of 473-673 K, pressure of 30 MPa, and reaction time of 20-60 min. The effects of temperature and reaction time were observed. The degradation of glycerol produced acetaldehyde, acrolein, allyl alcohol and un-identified products. The highest yield of acrolein, acetaldehyde and allyl alcohol were 0.20, 7.17, 96.69 mol%, respectively. Glycerol conversion was 99.92 mol%. While acetaldehyde was formed only in sub-critical water and allyl alcohol only in supercritical water, acrolein was formed in both. The kinetics of the global reaction displayed a pseudo-first-order. The activation energy at subcritical water was 39.6 kJ/mol. Based on the results, this method could be an efficient method for glycerol degradation because the high conversion of glycerol was obtained.     

Trypanosoma brucei: host parasite interaction in parasite destruction by salicylhydroxamic acid and glycerol in mice

Mouse blood and serum contain a synergistic factor which affects both the speed and completeness of destruction of Trypanosoma brucei in the presence of salicylhydroxamic acid (SHAM) and glycerol. The action of this factor is dose dependent producing complete killing in infected whole blood with 2 mM SHAM and 12 mM glycerol but not in a mixture of 20% infected whole blood and 80% buffer containing the same final concentration of SHAM and glycerol. This factor may account for the discrepancy in reports showing that SHAM-glycerol does not kill 100% of the exposed parasites in vitro yet is able to cure infected animals. The factor is not due to an acquired immune response, complement action, nor lipoproteins. Should the level of the factor be able to be increased, this could greatly increase the effectiveness of SHAM-glycerol.