High Salt Conditions Research Articles

Polyacrylamide adsorption on (1 0 1) quartz surfaces in saltwater for a range of pH values by molecular dynamics simulations

The adsorption of partially hydrolyzed polyacrylamide (HPAM) on quartz plays a key role in solid-liquid separation processes that seek to recover water for processing. In this work, computational molecular dynamics is used to study the water-quartz interface in the presence of HPAM under conditions of high salt and wide pH range. The salts used are mostly those of seawater. Small water-structure maker cations are preferentially adsorbed onto the polymer rather than onto the quartz surfaces. In freshwater, the adsorption of HPAM on quartz is reduced to very few contacts, however in saltwater the adsorption contacts of HPAM increase although decrease with surface charge, mainly due to electrostatic repulsion. In the presence of monovalent cations and for any surface charge on the quartz, above the isoelectric point, the adsorption contacts of HPAM decreases as the cation size increases, which is expected considering that smaller cations are more effective in neutralizing both quartz and HPAM. The results show that the adsorption of HPAM occurs exclusively via salt bridges. One way of describing the conformation of an HPAM chain adsorbed onto quartz is to reduce it to the skeleton of carbon atoms of the polymer chain and then determine the fraction of these atoms in loops, trains, and tails. In general, the adsorption contacts of HPAM are few, the carbon fractions in trains and loops are tiny, and therefore most of the carbon atoms in HPAM remain in long tails ready to get entangled with other tails thus favoring the flocculation process. The results are expected to contribute to sustainable water management through the right choice of flocculant based on molecular aspects.

RETRACTED ARTICLE: Characterization of DicB Inhibitory Activity in Cell Division Under Stress Conditions

In most bacteria, their chromosomes contain “cryptic”(or defective) prophages, which have lost genes required for the production of phage progeny. However, bacteria seem to have taken advantage of some cryptic prophage genes, albeit poorly characterized, to play various beneficial roles in bacterial host physiology. In this study, we focus on a cryptic-prophage-encoded small protein, DicB. Previously, we show that DicB interacts with MinC to result in cell division inhibition. By systematically probing DicB’s interaction with MinC using different DicB variants, we reveal that the entire N-terminal region of DicB participates in the interaction. We investigate the role of DicB in different physiological environments by monitoring the growth of E. coli under high salt conditions and in the presence of an acylampicillin antibiotic(Azlocillin). Our results demonstrate that DicB helps E. coli cope with high salt and Azlocillin stresses by impeding cell division. Under alkaline conditions, the inhibitory effect of DicB on E. coli cell division is also enhanced. Taken together, our work has shed further lights on the function of DicB, which has largely remained elusive.

GSK3-mediated stress signaling inhibits legume–rhizobium symbiosis by phosphorylating GmNSP1 in soybean

Legumes establish symbiotic associations with rhizobia for biological nitrogen fixation. This process is highly regulated by various abiotic stresses, but the underlying genetic and molecular mechanisms remain largely unknown. In this study, we discovered that the glycogen synthase kinase 3 (GSK3)-like kinase, GmSK2-8, plays an important role in inhibiting symbiotic signaling and nodule formation in soybean (Glycine max) under salt stress. We found that GmSK2-8 is strongly induced in soybean under high-salt conditions, while GmSK2-8 could interact with two G. max Nodulation Signaling Pathway 1 (GmNSP1) proteins, GmNSP1a and GmNSP1b; these key transcription factors are essential for rhizobial infection, nodule initiation, and symbiotic gene expression in soybean. Furthermore, we demonstrated that GmSK2-8 phosphorylates the LHRI domain of GmNSP1a, inhibits its binding to the promoters of symbiotic genes, and thus suppresses nodule formation under salt stress. Knockdown of GmSK2-8 and its close homologs also resulted in reduced plant sensitivity to salt stress during nodule formation. Taken together, our findings indicate that GSK3-like kinases directly regulate the activities of GmNSP1s to mediate salt-inhibited legume–rhizobium symbiosis, providing novel targets for improving symbiotic nitrogen fixation under environmental stress conditions in soybean and possibly other legumes.

Distinct ecotypes within a natural haloarchaeal population enable adaptation to changing environmental conditions without causing population sweeps.

Microbial communities thriving in hypersaline brines of solar salterns are highly resistant and resilient to environmental changes, and salinity is a major factor that deterministically influences community structure. Here, we demonstrate that this resilience occurs even after rapid osmotic shocks caused by a threefold change in salinity (a reduction from 34 to 12% salts) leading to massive amounts of archaeal cell lysis. Specifically, our temporal metagenomic datasets identified two co-occurring ecotypes within the most dominant archaeal population of the brines Haloquadratum walsbyi that exhibited different salt concentration preferences. The dominant ecotype was generally more abundant and occurred in high-salt conditions (34%); the low abundance ecotype always co-occurred but was enriched at salinities around 20% or lower and carried unique gene content related to solute transport and gene regulation. Despite their apparent distinct ecological preferences, the ecotypes did not outcompete each other presumably due to weak functional differentiation between them. Further, the osmotic shock selected for a temporal increase in taxonomic and functional diversity at both the Hqr. walsbyi population and whole-community levels supporting the specialization-disturbance hypothesis, that is, the expectation that disturbance favors generalists. Altogether, our results provide new insights into how intraspecies diversity is maintained in light of substantial gene-content differences and major environmental perturbations.

Energy-saving preparation of a bioflocculant under high-salt condition by using strain Bacillus sp. and the interaction mechanism towards heavy metals

A highly efficient bioflocculant, i.e., Na-Bsp was successfully prepared by using a tolerant strain-Bacillus sp. under high-salt condition without sterilization. Salt-containing medium was not infected by other strains throughout the whole incubation period in 168 h. The as-prepared Na-Bsp was found to be cation-dependent, exhibiting high flocculant efficiency (FE) i.e., 97.69 ± 0.61%, towards kaolin particles by aid of Fe3+. High FE values were well maintained under a wide pH range and/or boiled water treatment, likely because of the main constituent of polysaccharide. The presence of hydroxyl, carboxyl, and amine groups on the bioflocculant surface were possibly responsible for strong interactions with heavy metals. The adsorption capacities of Pb2+, Cu2+ and Cr6+ were 1000.0, 434.8 and 384.6 mg g−1, respectively. The changing of structure and configuration of bioflocculant during the metal adsorption were explored by the scanning electron microscope with electron energy loss spectroscopy and three-dimensional excitation-emission fluorescence spectrometry. This study provided a novel production method, whereby the conventional sterilization could be avoided, which is of great environmental significance for steam-saving. Furthermore, the as-prepared Na-Bsp exhibited high adsorption capacities toward heavy metals, which sheds lights on its potential usage as an alternative adsorbent.

Cation and Zn Accumulation in Brown Seeds of the Euhalophyte Suaeda salsa Improves Germination Under Saline Conditions.

Salinity inhibits plant growth due to salt ion accumulation in plant cells and reduced absorption of other nutrients such as metal ions; however halophyte plants have evolved mechanisms to survive and thrive in high-salt conditions. The euhalophyte Suaeda salsa generates dimorphic seeds (black and brown), which show marked differences in germination and seedling growth under high-salt conditions. However, it is unclear whether their ionic status differs. Here, to provide insight on the role of ions in salt tolerance, we used inductively coupled plasma mass spectrometry to measure the ion contents in the dimorphic seeds from S. salsa plants treated with or without NaCl. We measured the macroelements Na, K, Mg, and Ca, and the microelements Mn, Fe, Zn, Cu, and Mo. NaCl-treated S. salsa plants produced seeds with significantly reduced metallic element contents and significantly increased Na+ contents. The brown seeds of S. salsa plants treated with 0 and 200 mM NaCl had much higher contents of K+, Ca2+, and Fe2+ compared with the black seeds. However, the S. salsa seeds (both black and brown) from NaCl-treated plants were significantly larger, and had higher germination rate and higher seedling salt tolerance compared with seeds from plants not treated with NaCl. Interestingly, we measured significantly higher Zn2+ contents in the brown seeds from plants treated with NaCl compared with the black seeds. This suggests that the high contents of Zn2+ and other cations affected seed development and salt tolerance during germination under high-salt conditions. These observations provide insight into the mechanisms of salt tolerance in this halophyte and inform efforts to increase salt tolerance in salt-sensitive species.

DNA Terminal-Specific Dispersion Behavior of Polystyrene Latex Microparticles Densely Covered with Oligo-DNA Strands Under High-Salt Conditions.

We prepared microspheres densely covered with oligo-DNA strands by immobilizing amino-terminated oligo-DNA strands on the surface of carboxylate polystyrene latex (PS) particles via the amide bond formation. The obtained microspheres (ssDNA-PS) stably dispersed in neutral pH buffer containing high concentrations of NaCl. For the ssDNA-PS ≥1 μm diameter, only 3 - 5% of surface-immobilized oligo-DNA could form a duplex with the complementary strands. Nevertheless, the resulting ssDNA-PS showed a distinct duplex terminal dependency in their dispersion behavior under neutral pH and high NaCl conditions; the microspheres with fully-matched duplexes on the surface spontaneously aggregated in a non-crosslinking manner. By contrast, the microspheres with terminal-mismatched duplexes remained dispersed under the identical conditions. These results suggest that the micrometer-scale particles covered with oligo-DNA strands also have high susceptibility to a duplex terminal sequence in their dispersion property, similar to previously reported DNA-functionalized nanoparticles. This property could potentially be used in various applications including analytical purposes.

Na+ Efflux from Apple Dwarfing Rootstocks is Associated with High-Salt Resistance of Their Scions

In apple (Malus) cultivation, the adaptability of rootstocks has a fundamental influence on multiple abiotic-stress resistance properties of their scions. Here, we investigated the high-salt resistance of apple rootstocks, by treating 2-year-old apple trees consisting of the ‘Fuji’ cultivar grafted onto three different dwarfing rootstocks (SH6, M9-T337 and G935) with a high-salt solution for 30 days. We found that the high-salt stress caused leaf yellowing and growth inhibition to all apple plants, and that the most serious reduction in relative chlorophyll content, plant height and biomass accumulation was associated with the SH6 rootstock. In addition, based on the salt injury index, the high-salt resistance of the ‘Fuji’ scion on the three dwarfing rootstocks was ranked as G935 > M9-T337 > SH6. In addition, analysis of mineral elemental composition showed that the Na+ content in ‘Fuji’ leaves on the G935 rootstock increased less than twofold compared to the control, whereas those on the SH6 rootstock increased nearly 20-fold, accompanied with reduced K and Fe element absorption under high-salt treatments. Expression analysis of nine Na+ transport-related genes indicated that in the salt overly sensitive (SOS) pathway, the SOS1, SOS2 and SOS3 genes showed considerably greater induction by high-salt stress in G935 roots than in SH6 roots. Given the Na+ content detected in roots of different rootstocks, we propose that more efficient Na+ extracellular efflux in G935 roots, rather than intracellular Na+ compartmentalization, contributed to the improved characteristics of the G935 rootstock under high-salt conditions.

MicroRNA-133a-Dependent Inhibition of Proximal Tubule Angiotensinogen by Renal TNF (Tumor Necrosis Factor).

We showed that intrarenal suppression of TNF (tumor necrosis factor) production under low salt (LS) conditions increases renal cortical AGT (angiotensinogen) mRNA and protein expression. Intrarenal injection of murine recombinant TNF attenuated increases of AGT in mice ingesting LS. Moreover, AGT mRNA and protein expression increased ≈6-fold and 2-fold, respectively, in mice ingesting LS that also received an intrarenal injection of a lentivirus construct that specifically silenced TNF in the kidney (U6-TNF-ex4). Silencing of TNF under normal salt and high salt (HS) conditions also resulted in increased AGT expression. Since renal TNF production decreases in response to LS and increases in response to HS, the data suggest that alterations in TNF production under these conditions modulate the degree of AGT expression. We also tested the hypothesis that TNF inhibits intrarenal AGT expression by a mechanism involving miR-133a. Expression of miR-133a decreased in mice given LS and increased in response to HS for 7 days. Intrarenal silencing of TNF reversed the effects of HS on miR-133a-dependent AGT expression. In contrast, intrarenal TNF administration increased miR-133a expression in the kidney. Collectively, the data suggest that miR-133a is a salt-sensitive microRNA that inhibits AGT in the kidney and is increased by TNF. The HS-induced increase in blood pressure observed following silencing of TNF was markedly reduced upon intrarenal administration of miR-133a suggesting that intrinsic effects of TNF in the kidney to limit the blood pressure response to HS include an increase in miR-133a, which suppresses AGT expression.

Fast and easy quantitative characterization of methanotroph-photoautotroph cocultures.

Recent research has demonstrated that synthetic methanotroph-photoautotroph cocultures offer a highly promising route to convert biogas into value-added products. However, there is a lack of techniques for fast and accurate characterization of cocultures, such as determining the individual biomass concentration of each organism in real-time. To address this unsolved challenge, we propose an experimental-computational protocol for fast, easy, and accurate quantitative characterization of the methanotroph-photoautotroph cocultures. Besides determining the individual biomass concentration of each organism in the coculture, the protocol can also obtain the individual consumption and production rates of O2 and CO2 for the methanotroph and photoautotroph, respectively. The accuracy and effectiveness of the proposed protocol was demonstrated using two model coculture pairs, Methylomicrobium alcaliphilum 20ZR-Synechococcussp. PCC7002 that prefers high pH high salt condition, and Methylococcus capsulatus-Chlorella sorokiniana that prefers low salt and neutral pH medium. The performance of the proposed protocol was compared with a flow cytometry-based cell counting approach. The experimental results show that the proposed protocol is much easier to carry out and delivers faster and more accurate results in measuring individual biomass concentration than the cell counting approach without requiring any special equipment.

Research progress on effect of AP2/ERF transcription factors in regulating secondary metabolite biosynthesis

AP2/ERF transcription factor is a kind of transcription factors widely existing in plants, and contains at least a conserved AP2/ERF domain composed of about 60-70 amino acids. AP2/ERF transcription factors are widely involved in a variety of physiological processes in plants, including plant development, fruit ripening, flower development and other plant development processes, as well as such stress response processes as damage, pathogen defense, high-salt condition and drought. In recent years, secondary metabolic engineering that takes transcription factors as genetic manipulation targets has developed rapidly in improving the content of active ingredients and the quality of medicinal plants. This paper reviews the recent progress in the regulation of secondary metabolites biosynthesis with AP2/ERF transcription factors, and provides theoretical basis for the exploration of efficient regulatory targets, the regulation of secondary metabolites in medicinal plants, the targeted improvement of the content of active ingredients in traditional Chinese medicine, and the sustainable supply of high-quality traditional Chinese medicines.

Tartary buckwheat protein hydrolysates enhance the salt tolerance of the soy sauce fermentation yeast Zygosaccharomyces rouxii

Supplementation of protein hydrolysate is an important strategy to improve the salt tolerance of soy sauce aroma-producing yeast. In the present study, Tartary buckwheat protein hydrolysates (BPHs) were prepared and separated by ultrafiltration into LM-1 (<1 kDa) and HM-2 (1–300 kDa) fractions. The supplementation of HM-2 fraction could significantly improve cell growth and fermentation of soy sauce aroma-producing yeast Zygosaccharomyces rouxii As2.180 under high salt (12%, w/w) conditions. However, the LM-1 fraction inhibited strain growth and fermentation. The addition of HM-2 promoted yeast cell accumulation of K+, removal of cytosolic Na+ and accumulation of glycerol. Furthermore, the HM-2 fraction improved the cell membrane integrity and mitochondrial membrane and decreased intracellular ROS accumulation of the strain. The above results indicated that the supplementation of BPHs with a molecular weight of 1–300 kDa is a potentially effective and feasible strategy for improving the salt tolerance of soy sauce aroma-producing yeast Z. rouxii.

An analytical method to connect open curves for modeling protein-bound DNA minicircles

We introduce an analytical method to generate the pathway of a closed protein-bound DNA minicircle. We develop an analytical equation to connect two open curves smoothly and use the derived expressions to join the ends of two helical pathways and form models of nucleosome-decorated DNA minicircles. We find that the simplest smooth connector which satisfies the boundary conditions at the end points and the length requirement for such connections to be a quartic function on the xy-plane and linear along the z-direction. This is a general method which can be used to connect any two open curves with well defined mathematical definitions as well as pairs of discrete systems found experimentally. We used this method to describe the configurations of torsionally relaxed, 360-base pair DNA rings with two evenly-spaced, ideal nucleosomes. We considered superhelical nucleosomal pathways with different levels of DNA wrapping and allowed for different inter-nucleosome orientations. We completed the DNA circles with the smooth connectors and studied the associated bending and electrostatic energies for different configurations in the absence and presence of salt. The predicted stable states bear close resemblance to reconstituted minicircles observed under low and high salt conditions.

Characterization of the DREBA4-Type Transcription Factor (SlDREBA4), Which Contributes to Heat Tolerance in Tomatoes.

Dehydration-responsive element binding (DREB) transcription factors play crucial regulatory roles in abiotic stress. The only DREB transcription factor in tomato (Solanum lycopersicum), SlDREBA4 (Accession No. MN197531), which was determined to be a DREBA4 subfamily member, was isolated from cv. Microtom using high-temperature-induced digital gene expression (DGE) profiling technology. The constitutive expression of SlDREBA4 was detected in different tissues of Microtom plants. In addition to responding to high temperature, SlDREBA4 was up-regulated after exposure to abscisic acid (ABA), cold, drought and high-salt conditions. Transgenic overexpression and silencing systems revealed that SlDREBA4 could alter the resistance of transgenic Microtom plants to heat stress by altering the content of osmolytes and stress hormones, and the activities of antioxidant enzymes at the physiologic level. Moreover, SlDREBA4 regulated the downstream gene expression of many heat shock proteins (Hsp), as well as calcium-binding protein enriched in the pathways of protein processing in endoplasmic reticulum (ko04141) and plant-pathogen interaction (ko04626) at the molecular level. SlDREBA4 also induces the expression of biosynthesis genes in jasmonic acid (JA), salicylic acid (SA), and ethylene (ETH), and specifically binds to the DRE elements (core sequence, A/GCCGAC) of the Hsp genes downstream from SlDREBA4. This study provides new genetic resources and rationales for tomato heat-tolerance breeding and the heat-related regulatory mechanisms of DREBs.

Genome-Wide Identification and Analysis of SRO Gene Family in Chinese Cabbage (Brassica rapa L.).

Similar to radical-induced cell death 1 (SROs) is a family of small proteins unique to plants. SRO transcription factors play an important role in plants’ response to biotic and abiotic stresses. In this study, we identified 12 BrSRO genes in Chinese cabbage (Brassica rapa L.). Among them, a comprehensive overview of the SRO gene family is presented, including physical and chemical characteristics, chromosome locations, phylogenetic analysis, gene structures, motif analysis, and cis-element analyses. The number of amino acids of BrSRO genes is between 77–779 aa, isoelectric point changed from 6.02 to 9.6. Of the 12 BrSRO genes, 11 were randomly distributed along the 7 chromosomes, while BrSRO12 was located along unassigned scaffolds. Phylogenetic analysis indicated that the SRO proteins from six species, including Arabidopsis, banana, rice, Solanum lycopersicum, Zea mays, and Chinese cabbage were divided into eleven groups. The exon-rich BrSRO6 and BrSRO12 containing 15 exons were clustered to group K. All 12 genes have motif 2, which indicate that motif 2 is a relatively conservative motif. There are many hormone and stress response elements in BrSRO genes. The relative expression levels of 12 BrSRO genes under high temperature, drought, salt, and low temperature conditions were analyzed by real-time fluorescence quantitative PCR. The results indicated the relative expression level of BrSRO8 was significantly up-regulated when plants were exposed to high temperature. The relative expression levels of BrSRO1, 3, 7, 8, and 9 were higher under low temperature treatment. The up-regulated genes response to drought and salt stresses were BrSRO1, 5, 9 and BrSRO1, 8, respectively. These results indicated that these genes have certain responses to different abiotic stresses. This work has provided a foundation for further functional analyses of SRO genes in Chinese cabbage.

Antimicrobial Peptides with Enhanced Salt Resistance and Antiendotoxin Properties.

A strategy was described to design antimicrobial peptides (AMPs) with enhanced salt resistance and antiendotoxin activities by linking two helical AMPs with the Ala-Gly-Pro (AGP) hinge. Among the designed peptides, KR12AGPWR6 demonstrated the best antimicrobial activities even in high salt conditions (NaCl ~300 mM) and possessed the strongest antiendotoxin activities. These activities may be related to hydrophobicity, membrane-permeability, and α-helical content of the peptide. Amino acids of the C-terminal helices were found to affect the peptide-induced permeabilization of LUVs, the α-helicity of the designed peptides under various LUVs, and the LPS aggregation and size alternation. A possible model was proposed to explain the mechanism of LPS neutralization by the designed peptides. These findings could provide a new approach for designing AMPs with enhanced salt resistance and antiendotoxin activities for potential therapeutic applications.

Identification of yeast-derived emulsification proteins through analyses of proteins distributed into the emulsified phase

Emulsifiers are widely used in food manufacturing, and cell wall mannoproteins from Saccharomyces cerevisiae, a representative food yeast, have been proposed as potential new emulsifiers. However, their use has not become widespread. One reason is that the protein responsible for emulsification has not been identified so no efficient preparation method has been established. In this study, the emulsification substances were identified. Many mannoproteins are fixed to the cell wall via a glycosylphosphatidylinositol (GPI) anchor. Because emulsifying activity was found in the culture supernatant (CS) in gup1Δ with a mutation of GPI anchor synthesis, a protein distributed from the CS into the emulsified phase by emulsification treatment was analyzed. Using mass spectrometry, it was identified to be Gas1, a mannoprotein localized to the cell wall via a GPI anchor. Further, recombinant Gas1 without a C-terminal GPI anchor binding signal was purified, and it showed activity similar to bovine serum albumin, a well-known protein emulsifier. Gas1 also retained its activity under a wide range of pH and high salt conditions. Saccharomyces cerevisiae has Gas3 and Gas5, proteins homologous to Gas1, and recombinant Gas3 and Gas5 without the C-terminal signal were also purified and found to have emulsifying activity similar to that of recombinant Gas1. These results strongly suggest that Gas proteins take part in the emulsifying activity of yeast mannoproteins. It was also demonstrated that emulsification proteins could be identified by analyzing proteins distributed in an emulsified phase, so this method will be effective in finding new emulsification proteins.

Abstract P032: Dopamine Type 2 Receptor (D 2 R) Expression Modulates The Salt (NaCl) Induced Plasma Membrane Receptor Recruitment Of The Natriuretic Angiotensin Type 2 Receptor (AT 2 R) In Renal Proximal Tubule Cells Obtained From The Urine Of Salt Study Participants

The effect of D2R expression on the natriuretic AT2R plasma membrane recruitment in high (190 mM NaCl) and normal (140 mM NaCl) salt conditions was measured in human renal proximal tubule cells (RPTC) obtained from urine provided by salt study diet volunteers that were either salt resistant (SR) or inverse salt sensitive (ISS) (increased blood pressure on a low salt diet). Basal D2R expression was 36.9% ± 2.6% lower in ISS vs SR control n=5, p&lt;0.01). D2R expression in the SR was reduced by siRNA (37.1% ± 2.0% reduction in ISS vs SR control, n=5, p&lt;0.01, t-test). The ISS D2R expression was returned to normal levels by D2R overexpression using BacMam technology (22.5% ± 0.9% increase for ISS vs SR control siRNA, n=5, p&lt;0.01, t-test). Culturing SR and ISS cell lines in normal salt (NS, 140 mM NaCl) and high salt (HS, 190 mM NaCl) leads to the recruitment of AT2R to the cell surface in the ISS cell line (ISS Control: NS 47978 ± 2728 RFU vs HS 74056 ± 3002 RFU, n=5, p&lt;0.001, t-test), but not in the SR cell line. Knockdown of D2R using siRNA in the SR cell line altered the HS response in the SR cell line to that measured in the ISS cell line (SR D2R siRNA: NS 48514 ± 2560 RFU vs HS 82599 ± 1492 RFU, n=5, p&lt;0.001, t-test), and the difference between SR HS control siRNA and SR HS D2R siRNA is also highly significant (SR HS: control siRNA 60154 ± 3347 RFU vs SR HS D2R siRNA 82599 ± 1492 RFU, n=5, p&lt;0.001, t-test). Further lowering of D2R in ISS with D2R siRNA still showed a significant translocation of AT2R to the cell surface under HS (ISS D2R siRNA: NS 47953 ± 3058 RFU vs HS 80284 ± 2173 RFU, n-5, p&lt;0.001, t-test) but not a further enhancement over SR siRNA. Overexpression of D2R in the ISS cell line completely blocked the HS AT2R cell surface recruitment, thus converting the ISS HS phenotype of ISS to a cell line that resembled a SR cell line. In conclusion, we have shown that a clear ISS phenotype of HS AT2R plasma membrane recruitment can be replicated in an SR cell line by reducing D2R expression using siRNA to levels seen in an ISS cell line. Similarly, overexpressing D2R in an ISS cell line to a level seen in SR cells reverts the ISS cells back to a SR associated sodium induced AT2R cell surface recruitment.

6S-2 RNA deletion in the undomesticated B. subtilis strain NCIB 3610 causes a biofilm derepression phenotype

ABSTRACT Bacterial 6S RNA regulates transcription via binding to the active site of RNA polymerase holoenzymes. 6S RNA has been identified in the majority of bacteria, in most cases encoded by a single gene. Firmicutes including Bacillus subtilis encode two 6S RNA paralogs, 6S-1 and 6S-2 RNA. Hypothesizing that the regulatory role of 6S RNAs may be particularly important under natural, constantly changing environmental conditions, we constructed 6S RNA deletion mutants of the undomesticated B. subtilis wild-type strain NCIB 3610. We observed a strong phenotype for the ∆6S-2 RNA strain that showed increased biofilm formation on solid media and the ability to form surface-attached biofilms in liquid culture. This phenotype remained undetected in derived laboratory strains (168, PY79) that are defective in biofilm formation. Quantitative RT-PCR data revealed transcriptional upregulation of biofilm marker genes such as tasA, epsA and bslA in the ∆6S-2 RNA strain, particularly during transition from exponential to stationary growth phase. Salt stress, which blocks sporulation at a very early stage, was found to override the derepressed biofilm phenotype of the ∆6S-2 RNA strain. Furthermore, the ∆6S-2 RNA strain showed retarded swarming activity and earlier spore formation. Finally, the ∆6S-1&2 RNA double deletion strain showed a prolonged lag phase of growth under oxidative, high salt and alkaline stress conditions, suggesting that the interplay of both 6S RNAs in B. subtilis optimizes and fine-tunes transcriptomic adaptations, thereby contributing to the fitness of B. subtilis under the unsteady and temporarily harsh conditions encountered in natural habitats.

Effective removal of radioactive cesium from contaminated water by synthesized composite adsorbent and its thermal treatment for enhanced storage stability

A composite adsorbent for the removal of radioactive cesium (137Cs) was synthesized by immobilizing potassium cobalt ferrocyanide in the micro pores of the zeolite chabazite. The synthetically optimized composite adsorbent demonstrates a rapid cesium adsorption rate under both salt-free and high-salt conditions with a high distribution coefficient of cesium (≥105 mL/g). Although both components have the same ion-exchange reaction between potassium and cesium, the reaction by ferrocyanide component was predominant, which derived hundred times higher distribution coefficient of the composite adsorbent than that of pure chabazite. A thermal stabilization process was studied for improving the storage and/or disposal stability of the spent adsorbent. The formation of a eutectic system within the spent adsorbent reduced the stabilization temperature to 1000 °C from 1200 °C. Accordingly, the leaching of cesium was remarkably reduced by the remineralization to the stable pollucite. The stable impregnation of ferrocyanide component in the chabazite pores derived the reduction of cesium volatility enabling the high temperature stabilization method. Our experimental results provide evidence that the composite adsorbent has clear advantages on the cesium removal from contaminated water and its stabilization via thermal-treatment.