High Ca2 Research Articles

Chemical processes of wintertime aerosols over the East China Sea based on aircraft and ground measurements: Comparison with the Sea of Japan

Aircraft and ground-level observations of wintertime aerosols over the East China Sea (ECS) around Japan's southwestern islands were conducted from the boundary layer to the middle troposphere (0–4.5 km) and compared to those over the Sea of Japan (SOJ) during the same period, for the purpose of comprehensive elucidation on modification process of chemical composition in aerosols at the Asian outflow receptor regions. The deficient values of Cl− in both cases for ECS and SOJ were higher at ground level than at high altitudes because of the acidic gas (HNO3, H2SO4) concentrations. Most Na+ and Cl− at high altitudes and at ground level originated from sea salt, because the (Na+ + Cl−) concentrations of which in the boundary layer observed were linearly related to the production flux of sea spray aerosol. The contribution of sea salt aerosols to cloud condensation nuclei appears to be low over the ECS, contrary to the SOJ. The non-sea salt (nss)-K+ concentrations and the path of backward trajectories suggest a significant impact of biomass burning on the SOJ associated with woodburning for residential heating in the Korean Peninsula. A similar difference was observed in NH4+/nss-SO42– equivalent ratios (∼0.5 for the ECS; ∼1 for the SOJ), which likely indicates ammonium sulfate aerosols produced in urban and industrial regions of Korea. The high aerosol Ca2+ concentration in the boundary layer over the ECS was accompanied by those of Na+, Cl−, NO3−, and nss-SO42– during cold front passages, as observed in SOJ. This indicates that Ca(NO3)2, CaSO4, and CaCl2 were formed via the reactions of acidic gases and Ca-rich dust particles from desert areas in the Asian continent, followed by the production of NaNO3 by uptake of acidic gases into sea salt in the ECS. This notion is supported by high Se(VI)/Se (IV) ratios (>2) that indicate an oxidative process during long-range transport from coal combustion sources.

Adhesion GPCR Gpr126 (Adgrg6) Expression Profiling in Zebrafish, Mouse, and Human Kidney.

Adhesion G protein-coupled receptors (aGPCRs) comprise the second-largest class of GPCRs, the most common target for approved pharmacological therapies. aGPCRs play an important role in development and disease and have recently been associated with the kidney. Several aGPCRs are expressed in the kidney and some aGPCRs are either required for kidney development or their expression level is altered in diseased kidneys. Yet, general aGPCR function and their physiological role in the kidney are poorly understood. Here, we characterize in detail Gpr126 (Adgrg6) expression based on RNAscope® technology in zebrafish, mice, and humans during kidney development in adults. Gpr126 expression is enriched in the epithelial linage during nephrogenesis and persists in the adult kidney in parietal epithelial cells, collecting ducts, and urothelium. Single-cell RNAseq analysis shows that gpr126 expression is detected in zebrafish in a distinct ionocyte sub-population. It is co-detected selectively with slc9a3.2, slc4a4a, and trpv6, known to be involved in apical acid secretion, buffering blood or intracellular pH, and to maintain high cytoplasmic Ca2+ concentration, respectively. Furthermore, gpr126-expressing cells were enriched in the expression of potassium transporter kcnj1a.1 and gcm2, which regulate the expression of a calcium sensor receptor. Notably, the expression patterns of Trpv6, Kcnj1a.1, and Gpr126 in mouse kidneys are highly similar. Collectively, our approach permits a detailed insight into the spatio-temporal expression of Gpr126 and provides a basis to elucidate a possible role of Gpr126 in kidney physiology.

A high-salt diet promotes hypertrophic scarring through TRPC3-mediated mitochondrial Ca2+ homeostasis dysfunction

Diet High in salt content have been associated with cardiovascular disease and chronic inflammation. We recently demonstrated that transient receptor potential canonical 3 (TRPC3) channels regulate myofibroblast transdifferentiation in hypertrophic scars. Here, we examined how high salt activation of TRPC3 participates in hypertrophic scarring during wound healing. In vitro, we confirmed that high salt increased the TRPC3 protein expression and the marker of myofibroblast alpha smooth muscle actin (α-SMA) in wild-type mice (WT) primary cultured dermal fibroblasts but not Trpc3−/− mice. Activation of TRPC3 by high salt elevated cytosolic Ca2+ influx and mitochondrial Ca2+ uptake in dermal fibroblasts in a TRPC3-dependent manner. High salt activation of TRPC3 enhanced mitochondrial respiratory dysfunction and excessive ROS production by inhibiting pyruvate dehydrogenase action, that activated ROS-triggered Ca2+ influx and the Rho kinase/MLC pathway in WT mice but not Trpc3−/− mice. In vivo, a persistent high-salt diet promoted myofibroblast transdifferentiation and collagen deposition in a TRPC3-dependent manner. Therefore, this study demonstrates that high salt enhances myofibroblast transdifferentiation and promotes hypertrophic scar formation through enhanced mitochondrial Ca2+ homeostasis, which activates the ROS-mediated pMLC/pMYPT1 pathway. TRPC3 deficiency antagonizes high salt diet-induced hypertrophic scarring. TRPC3 may be a novel target for hypertrophic scarring during wound healing.

Calcium and ammonium now control the pH of wet and bulk deposition in Ohio, U.S.

As precipitation acidity in the United States has decreased dramatically over the past forty years, new questions have emerged about the role of base cations and nitrogen (N) species in regulating precipitation pH. To address these questions, we studied precipitation chemistry in Ohio, a state with relatively high N deposition and a mix of urban, industrial, and agricultural land use. We used long-term data from the National Atmospheric Deposition Program (NADP) to assess temporal changes in the drivers of wet deposition pH in Ohio. We supplemented our analysis with short-term data on spatial patterns of bulk deposition pH collected along an agricultural-to-urban transect in central Ohio. From 1979 to 2019, wet deposition pH at the Ohio NADP sites increased from 4.22 ± 0.05 to 5.33 ± 0.21, and the cation-to-anion ratio increased from 0.92 ± 0.02 to 1.35 ± 0.06, due to a dramatic decline in measured anions. As correlations between wet deposition pH and the anions SO42− and NO3− weakened, correlations between wet deposition pH and the cations NH4+ and Ca2+ strengthened, suggesting that these cations are playing a larger role in controlling precipitation pH today. In recent years (2021–2022), NH4+ was significantly correlated with bulk deposition pH in all land uses except the urban site, with the strongest correlation at the rural/agricultural site, where the pH was 5.96 ± 0.49. Similarly, Ca2+ was strongly and significantly correlated with bulk deposition pH across all land uses. For Ca2+, the urban site was distinct from the other sites due to the high pH (6.58 ± 0.44) and Ca2+ concentrations at that site, likely driven by high levels of particulate matter deposition. Our results indicate that land use plays a role in the strength and dominant process of acid neutralization, with Ca-rich dust more important in urban areas and reduced N more important in agricultural regions. As precipitation pH increases and land use changes across the country, base cations and reduced N will play an increasingly important role in regulating precipitation pH in the U.S., with important implications for ecosystems continuing to recover from acid rain.

Pushing the Limits of Biosensing: Selective Calcium Ion Detection with High Sensitivity via High-k Gate Dielectric Engineered Si Nanowire Random Network Channel Dual-Gate Field-Effect Transistors.

Calcium ions (Ca2+) are abundantly present in the human body; they perform essential roles in various biological functions. In this study, we propose a highly sensitive and selective biosensor platform for Ca2+ detection, which comprises a dual-gate (DG) field-effect transistor (FET) with a high-k engineered gate dielectric, silicon nanowire (SiNW) random network channel, and Ca2+-selective extended gate. The SiNW channel device, which was fabricated via the template transfer method, exhibits superior Ca2+ sensing characteristics compared to conventional film channel devices. An exceptionally high Ca2+ sensitivity of 208.25 mV/dec was achieved through the self-amplification of capacitively coupled DG operation and an enhanced amplification ratio resulting from the high surface-to-volume ratio of the SiNW channel. The SiNW channel device demonstrated stable and reliable sensing characteristics, as evidenced by minimal hysteresis and drift effects, with the hysteresis voltage and drift rate measuring less than 6.53% of the Ca2+ sensitivity. Furthermore, the Ca2+-selective characteristics of the biosensor platform were elucidated through experiments with pH buffer, NaCl, and KCl solutions, wherein the sensitivities of the interfering ions were below 7.82% compared to the Ca2+ sensitivity. The proposed Ca2+-selective biosensor platform exhibits exceptional performance and holds great potential in various biosensing fields.

Compartment-specific Ca2+ imaging in the green alga Chlamydomonas reinhardtii reveals high light-induced chloroplast Ca2+ signatures.

To investigate the role of intracellular Ca2+ signaling in the perception and response mechanisms to light in unicellular microalgae, the genetically encoded ratiometric Ca2+ indicator Yellow Cameleon (YC3.6) was expressed in the model organism for green algae Chlamydomonas reinhardtii, targeted to cytosol, chloroplast, and mitochondria. Through invivo single-cell confocal microscopy imaging, light-induced Ca2+ signaling was investigated in different conditions and different genotypes, including the photoreceptors mutants phot and acry. A genetically encoded H2 O2 sensor was also adopted to investigate the possible role of H2 O2 formation in light-dependent Ca2+ signaling. Light-dependent Ca2+ response was observed in Chlamydomonas reinhardtii cells only in the chloroplast as an organelle-autonomous response, influenced by light intensity and photosynthetic electron transport. The absence of blue and red-light photoreceptor aCRY strongly reduced the light-dependent chloroplast Ca2+ response, while the absence of the blue photoreceptor PHOT had no significant effects. A correlation between high light-induced chloroplast H2 O2 gradients and Ca2+ transients was drawn, supported by H2 O2 -induced chloroplast Ca2+ transients in the dark. In conclusion, different triggers are involved in the light-induced chloroplast Ca2+ signaling as saturation of the photosynthetic electron transport, H2 O2 formation, and aCRY-dependent light perception.

The impacts of nicotinamide and inositol on the available cells and product performance of industrial baker's yeasts

A suitable nutrient supply, especially of vitamins, is very significant for the deep display of the inherent genetic properties of microorganisms. Here, using the chemically defined minimal medium (MM) for yeast, nicotinamide and inositol were confirmed to be more beneficial for the performance of two industrial baker's yeasts, a conventional and a high-sugar-tolerant strain. Increasing nicotinamide or inositol to proper levels could enhance the both strains on cell growth and activity and product performance, including trehalose accumulation and leavening performance. The activity of key enzymes (PCK, TPS) and the content of intermediate metabolites (G6P, UDPG) in the trehalose synthesis pathway were promoted by a moderate supply of nicotinamide and inositol. That were also proved that an appropriate amount of niacinamide promoted the transcription of longevity-related genes (PNC1, SIR2), and the proper concentration of inositol altered the phospholipid composition in cells, namely, phosphatidylinositol and phosphatidyl choline. Furthermore, the cell growth and the leavening performance of the both strains were promoted after adjusting inositol to choline to the proper ratio, resulting directly in content changes of phosphatidylinositol and phosphatidyl choline in the cells. While the two strains responded to the different proper ratio of inositol to choline probably due to their specific physiological characteristics. Such beneficial effects of increased nicotinamide levels were confirmed in natural media, molasses and corn starch hydrolyzed sugar media. Meanwhile, such adjustment of inositol to choline ratio could lessen the inhibition of excess inositol on cell growth of the two tested strains in corn starch hydrolyzed sugar media. However, in molasse, such phenomenon was not observed probably since there was higher Ca2+ in it. The results indicated that the effects of nutrient factors, such as vitamins, on cell growth and other properties found out from the simple chemically defined minimal medium were an effective measure to use in improving the recipe of natural media at least for baker's yeast.

Influence of the aquatic environment and 1α,25(OH)2 vitamin D3 on calcium influx in the intestine of adult zebrafish

We investigated the effects of environment calcium challenge and 1α,25(OH)2 vitamin D3 (1,25-D3) on 45Ca2+ influx in the intestine of zebrafish (ZF). In vitro45Ca2+ influx was analyzed using intestines from fed and fasted fish. ZF were held in water containing Ca2+ (0.02, 0.7, 2.0 mM) to analyze the ex vivo45Ca2+ influx in the intestine and for histology. Intestines from fish held in water with Ca2+ were incubated ex vivo to characterize ion channels, receptors, ATPases and ion exchangers that orchestrate 45Ca2+ influx. For in vitro studies, intestines were incubated with antagonists/agonist or inhibitors to study the mechanism of 1,25-D3 on 45Ca2+ influx. Fasted ZF reached a plateau for 45Ca2+ influx at 30 min. In vivo fish at high Ca2+ stimulated ex vivo45Ca2+ influx and increased the height of intestinal villi in low calcium. In the normal calcium, 45Ca2+ influx was maintained by the reverse-mode Na+/Ca2+ (NCX) activation, Na+/K+-ATPase pump and sarco/endoplasmic reticulum calcium ATPase (SERCA) pump. However, Ca2+ hyperosmolarity is supported by L-type voltage-dependent calcium channels (L-VDCC), transient receptor potential vanilloid subfamily 1 (TRPV1) and Na+/K+-ATPase activity. The calcium challenge causes morphological alteration and changes the ion type-channels involved in the intestine to maintain hyperosmolarity. 1,25-D3 stimulates Ca2+ influx in normal osmolarity coordinated by L-VDCC activation and SERCA inhibition to keeps high intracellular calcium in intestine. Our data showed that the adult ZF regulates the calcium challenge (per se osmolarity), independently of the hormonal regulation to maintain the calcium balance through the intestine to support ionic adaptation.

Distinct microbial structure and metabolic potential shaped by significant environmental gradient impacted by ferrous slag weathering

Alkaline ferrous slags pose global environmental issues and long-term risks to ambient environments. To explore the under-investigated microbial structure and biogeochemistry in such unique ecosystems, combined geochemical, microbial, ecological and metagenomic analyses were performed in the areas adjacent to a ferrous slag disposal plant in Sichuan, China. Different levels of exposure to ultrabasic slag leachate had resulted in a significant geochemical gradient of pH (8.0–12.4), electric potential (−126.9 to 437.9 mV), total organic carbon (TOC, 1.5–17.3 mg/L), and total nitrogen (TN, 0.17–1.01 mg/L). Distinct microbial communities were observed depending on their exposure to the strongly alkaline leachate. High pH and Ca2+ concentrations were associated with low microbial diversity and enrichment of bacterial classes Gamma-proteobacteria and Deinococci in the microbial communities exposed to the leachate. Combined metagenomic analyses of 4 leachate-unimpacted and 2-impacted microbial communities led to the assembly of one Serpentinomonas pangenome and 81 phylogenetically diversified metagenome assembled genomes (MAGs). The prevailing taxa in the leachate-impacted habitats (e.g., Serpentinomonas and Meiothermus spp.) were phylogenetically related to those in active serpentinizing ecosystems, suggesting the analogous processes between the man-made and natural systems. More importantly, they accounted for significant abundance of most functional genes associated with environmental adaptation and major element cycling. Their metabolic potential (e.g., cation/H+ antiporters, carbon fixation on lithospheric carbon source, and respiration coupling sulfur oxidization and oxygen or nitrate reduction) may support these taxa to survive and prosper in these unique geochemical niches. This study provides fundamental understandings of the adaptive strategies of microorganisms in response to the strong environmental perturbation by alkali tailings. It also contributes to a better comprehension of how to remediate environments affected by alkaline industrial material.

Revealing Low Amplitude Signals of Neuroendocrine Cells through Disordered Silicon Nanowires-Based Microelectrode Array.

Today, the key methodology to study in vitro or in vivo electrical activity in a population of electrogenic cells, under physiological or pathological conditions, is by using microelectrode array (MEA). While significant efforts have been devoted to develop nanostructured MEAs for improving the electrophysiological investigation in neurons and cardiomyocytes, data on the recording of the electrical activity from neuroendocrine cells with MEA technology are scarce owing to their weaker electrical signals. Disordered silicon nanowires (SiNWs) for developing a MEA that, combined with a customized acquisition board, successfully capture the electrical signals generated by the corticotrope AtT-20cells as a function of the extracellular calcium (Ca2+ ) concentration are reported. The recorded signals show a shape that clearly resembles the action potential waveform by suggesting a natural membrane penetration of the SiNWs. Additionally, the generation of synchronous signals observed under high Ca2+ content indicates the occurrence of a collective behavior in the AtT-20cell population. This study extends the usefulness of MEA technology to the investigation of the electrical communication in cells of the pituitary gland, crucial in controlling several essential human functions, and provides new perspectives in recording with MEA the electrical activity of excitable cells.

1749-P: Influence of the Biomechanical Environment on Islet Function and Maturity

It is well-established that cells respond to mechanical cues via cytoskeletal remodeling. However, it is not known whether the mechanical environment influences β-cell maturity and function. To examine how mechanical cues influence the β-cell, we used biocompatible substrates with tunable mechanical properties synthesized with elastic moduli ranging from ~3kPa-33 kPa. The surface was coated with extracellular matrix and MIN6 β-like cells were seeded. To independently examine a link between β-cell function and maturity, we examined islets from mice in which β-cells express CaMPARI, a photoconvertible fluorescent protein that in the presence of high Ca2+ activity changes from green to red. For all conditions in MIN6 cells and CAMPARI-expressing islets, we imaged Ca2+ dynamics via Fluo4 at low (2mM) and high glucose (11, 20mM). qPCR was conducted on MIN6 cells (6, 22 kPa) and flow-sorted CaMPARI-expressing β-cells (green, red) to examine expression of genes linked to β-cell function and maturity. With increased substrate stiffness, MIN6 cell Ca2+ oscillations were more robust, including a significant increase in duty cycle (p<0.01) and were more coordinated, consistent with increased excitability. With increasing stiffness, there was significantly decreased expression of Sur1, Kir6.2, Ins2, Pdx1, Fltp, and Ecad (p<0.01). Thus, the dynamics and coordination of Ca2+ activity is mechanoresponsive and may result from altered β-cell maturity. In CaMPARI islets, Ca2+ oscillations were more robust and coordinated for photo-converted red cells which marks cells with higher Ca2+, compared to green cells. In these red cells that show higher Ca2+, qPCR showed significantly increased expression of cFos, but decreased expression of Pdx1 and Ins2, again showing more excitable cells showed altered maturity. In conclusion, our results suggest there may be an inverse relationship between β-cell maturity and function. Further, that the maturity and function of β-cells is responsive to the mechanical environment. Disclosure K.Vazquez: None. R.K.Benninger: None. Funding National Institutes of Health (R01DK102950, R01DK106412)

Complexation between egg yolk protein hydrolysate, phytic acid and calcium ion: Binding mechanisms and influence on protein digestibility and calcium uptake

Phytic acid (PA) is an antinutrient that can affect calcium (Ca2+) and nutrient absorption in the human body. In this study, a novel egg yolk protein hydrolysate (EYPH) with high Ca2+-binding ability was prepared. The interaction between EYPH, PA and Ca2+ and the influence of these interactions on protein digestibility and Ca2+ transport was studied. Isothermal titration calorimetry (ITC) technology was used to explore the interaction mechanism between EYPHs, PA and Ca2+ at pH 2.0 and 7.0. Results showed that the binary interactions (PA and Ca2+, Ca2+ and EYPHs, EYPHs and PA) and ternary interaction occurred (PA, Ca2+ and EYPHs) at pH 7.0. However, under the condition of pH 2.0, only the binary interaction between EYPH and PA was performed and the ternary complex was not found. The above interaction significantly (p < 0.05) influenced protein digestibility and Ca2+ transport in vitro. PA significantly (p < 0.05) decreased the digestibility of EYPH and an increase was seen after the calcium chloride addition in the PA-EYPH reaction system. Besides, PA significantly (p < 0.05) decreased the Ca2+ transport (77%) in the small intestine, but it presented a significant (p < 0.05) increase after the EYPH addition (3.62 time). These results can provide important insights for studying the interactions, protein behavior and Ca2+ uptake of complex mixtures.

Neuroprotective role of calreticulin after spinal cord injury in mice

Accumulating evidence suggests that endoplasmic reticulum (ER) stress and unfolded protein response (UPR) are involved in the pathology of spinal cord injury (SCI). To determine the role of the UPR-target molecule in the pathophysiology of SCI, we analyzed the expression and the possible function of calreticulin (CRT), a molecular chaperone in the ER with high Ca2+ binding capacity, in a mouse SCI model. Spinal cord contusion was induced in T9 by using the Infinite Horizon impactor. Quantitative real-time polymerase chain reaction confirmed increase of Calr mRNA after SCI. Immunohistochemistry revealed that CRT expression was observed mainly in neurons in the control (sham operated) condition, while it was strongly observed in microglia/macrophages after SCI. Comparative analysis between wild-type (WT) and Calr+/- mice revealed that the recovery of hindlimb locomotion was reduced in Calr+/- mice, based on the evaluation using the Basso Mouse Scale and inclined-plane test. Immunohistochemistry also revealed more accumulation of immune cells in Calr+/- mice than in WT mice, at the epicenter 3 days and at the caudal region 7 days after SCI. Consistently, the number of damaged neuron was higher in Calr+/- mice at the caudal region 7 days after SCI. These results suggest a regulatory role of CRT in the neuroinflammation and neurodegeneration after SCI.

Presence of Extracellular Alpha-Synuclein Aggregates Trigger Astrocytic Degeneration Through Enhanced Membrane Rigidity and Deregulation of Store-Operated Calcium Entry (SOCE) into the Endoplasmic Reticulum.

α-Synuclein has a critical role in Parkinson's disease, but the mechanism of how extracellular α-synuclein aggregates lead to astrocytic degeneration remains unknown. Our recent study in astrocytes highlighted that α-synuclein aggregates undergo lower endocytosis than the monomeric-form, even while displaying a higher impact on glutathione-machinery and glutamate-metabolism under sublethal conditions. As optimal intracellular calcium levels are essential for these functions, we aimed to study the effect of extracellular α-synuclein aggregates on ER calcium entry. We assessed the association of extracellular aggregated-α-synuclein (WT and A30P/A53T double-mutant) with the astrocytic membrane (lipid rafts) and studied its effects on membrane fluidity, ER stress, and ER calcium refilling in three systems-purified rat primary midbrain astrocyte culture, human iPSC-derived astrocytes, and U87 cells. The corresponding timeline effect on mitochondrial membrane potential was also evaluated. Post-24h exposure to extracellular WT and mutant α-synuclein aggregates, fluorescence-based studies showed a significant increase in astrocyte membrane rigidity over control, with membrane association being significantly higher for the double mutant aggregates. α-Synuclein aggregates also showed preferentially higher association with lipid rafts of astrocytic membrane. A simultaneous increase in ER stress markers (phosphorylated PERK and CHOP) with significantly higher SOCE was also observed in aggregate-treated astrocytes, with higher levels for double mutant variant. These observations correlate with increased expression of SOCE markers, especially Orai3, on plasma membrane. Alterations in mitochondrial membrane potential were only noted post-48h of exposure to α-synuclein aggregates. We therefore suggest that in astrocytes, α-synuclein-aggregates preferentially associate with lipid rafts of membrane, altering membrane fluidity and consequently inducing ER stress mediated by interaction with membrane SOCE proteins, resulting in higher Ca2+ entry. A distinct cascade of events of sequential impairment of ER followed by mitochondrial alteration is observed. The study provides novel evidence elucidating relationships between extracellular α-synuclein aggregates and organellar stress in astrocytes and indicates the therapeutic potential in targeting the association of α-synuclein aggregates with astrocytic membrane.

Impacts of divalent cations (Mg2+ and Ca2+) on PFAS bioaccumulation in freshwater macroinvertebrates representing different foraging modes

Per- and polyfluoroalkyl substances (PFAS) have extensively contaminated freshwater aquatic ecosystems where they can be transported in water and partition to sediment and biota. In this paper, three freshwater benthic macroinvertebrates with different foraging modes were exposed to environmentally relevant concentrations of eight perfluoroalkyl carboxylates (PFCA), three perfluoroalkyl sulfonates (PFSA), and three fluorotelomer sulfonates (FTS) at varying divalent cation concentrations of magnesium (Mg2+) and calcium (Ca2+). Divalent cations can impact PFAS partitioning to solids, especially to sediments, at higher concentrations. Sediment dwelling worms (Lumbriculus variegatus), epibenthic grazing snails (Physella acuta), and sediment-dwelling filter-feeding bivalves (Elliptio complanata) were selected due to their unique foraging modes. Microcosms were composed of synthetic sediment, culture water, macroinvertebrates, and PFAS and consisted of a 28-day exposure period. L. variegatus had significantly higher PFAS bioaccumulation than P. acuta and E. complanata, likely due to higher levels of interactions with and ingestion of the contaminated sediment. “High Mg2+” (7.5 mM Mg2+) and “High Ca2+” (7.5 mM Ca2+) conditions generally had statistically higher bioaccumulation factors (BAF) than the “Reference Condition” (0.2 mM Ca2+ and 0.2 mM Mg2+) for PFAS with perfluorinated chain lengths greater than eight carbons. Long-chain PFAS dominated the PFAS profiles of the macroinvertebrates for all groups of compounds studied (PFCA, PFSA, and FTS). These results indicate that the study organism has the greatest impact on bioaccumulation, although divalent cation concentration had observable impacts between organisms depending on the environmental conditions. Elevated cation concentrations in the microcosms led to significantly greater bioaccumulation in the test organisms compared to the experimental reference conditions for long-chain PFAS.

Hydrogeochemical Characteristics and Human Health Risk Assessment of Fluoride Enrichment in Water in Faulted Basins of Qinghai-Tibet Plateau—A Case Study of Sanhe Plain in Guide Basin

Fluoride (F) is an essential element of drinking water for human health, especially for bone development and enamel creation. However, if the fluoride content in drinking water is higher than 1.5 mg/L or lower than 0.5 mg/L, it will cause endemic diseases, such as dental fluorosis. There are two main hydrogeological characteristics: the properties of the water-bearing rocks and groundwater conditions controlled the groundwater in guide basin. The geothermal water can be divided into fracture convection and sedimentary basin geothermal water according to its geological environment and heat transfer mode. Inductively coupled plasma spectrometry is a significant tool for groundwater quality analysis. The geochemical factors of fluoride enrichment in confined geothermal water mainly include pH, ion exchange, and mineral saturation. Both groundwater samples are slightly alkaline, while the phreatic water and surface water record pH values of 8.5, 7.78, and 7.8, respectively. The salinity of groundwater water is not high, but for confined geothermal water, phreatic water, and surface water measures 706.0, 430.1 and 285.9 mg/L respectively. The higher the pH of groundwater, the more beneficial it is to the enrichment of fluoride. In contrast, the main cations in phreatic water and surface water are calcium ions and magnesium ions. The anions in groundwater and surface water mainly include SO42− and HCO3−, followed by Cl−, indicating that the groundwater and surface water here is mainly leaching. Fluoride was shown to be positively correlated with sodium and bicarbonate. Moreover, the results indicate that F− enrichment is usually associated with high HCO3− and Na+ concentrations in water, while a high Ca2+ concentration tends to lower the F− concentration in water. This means that the ion exchange between calcium ions and sodium ions may lead to fluoride enrichment in natural water. As mentioned above, high-sodium and low-calcium water are favorable for fluoride enrichment. Moreover, saturation indices of fluorite, gypsum, dolomite, and calcite, as well as the saturation index of fluorite, represent a vital method to understand the fluoride enrichment. According to this study, fluoride as a pollutant poses great risks to human health overall, whether lower than or higher than the drinking water limit. Children face higher health risks than adults caused by confined geothermal water drinking intake. This study suggests that groundwater treatment should be conducted to reduce fluoride concentration in drinking water. It is suggested that when confined geothermal water is used as drinking water, it should be mixed with phreatic water and surface water in a certain proportion to make the fluoride in groundwater reach the range of safe drinking water.

Application of inverse modelling for prediction of the surface water chemistry of the ekulu river in enugu, southeastern nigeria

Surface water chemistry evolution of Ekulu River was conducted by inverse geochemical modelling using the PHREEQC computer program. In this study, samples were collected from the Ekulu river at 100m intervals, and were taken to the laboratory for major anions and cations, heavy metal and bacterial content analyses. Inverse geochemical modelling results reveal that the river evolved as a result of dissolution of siderite, quartz, gypsum, galena, sphalerite, pyrolusite and precipitation of goethite and pyrite. The Piper diagram indicates Calcium-Chloride water type, with high Ca2+ + Mg+ and Cl- + SO42 contents, which is typical of water originated from gypsum dissolution and mine drainage. The results of the analyses show that the water cannot be recommended for drinking because the E. coli and coliform contents are higher than the permissible limits. The water chemistry of Ekulu river is as a result of secondary minerals dissolution and mine drainage from Onyeama coal mine whereas the microbial content resulted from pollution from recent faeces.&#x0D; &#x0D;

Aging affects GABAergic function and calcium homeostasis in the mammalian central clock.

Aging impairs the function of the central circadian clock in mammals, the suprachiasmatic nucleus (SCN), leading to a reduction in the output signal. The weaker timing signal from the SCN results in a decline in rhythm strength in many physiological functions, including sleep-wake patterns. Accumulating evidence suggests that the reduced amplitude of the SCN signal is caused by a decreased synchrony among the SCN neurons. The present study was aimed to investigate the hypothesis that the excitation/inhibition (E/I) balance plays a role in synchronization within the network. Using calcium (Ca2+) imaging, the polarity of Ca2+ transients in response to GABA stimulation in SCN slices of old mice (20-24 months) and young controls was studied. We found that the amount of GABAergic excitation was increased, and that concordantly the E/I balance was higher in SCN slices of old mice when compared to young controls. Moreover, we showed an effect of aging on the baseline intracellular Ca2+ concentration, with higher Ca2+ levels in SCN neurons of old mice, indicating an alteration in Ca2+ homeostasis in the aged SCN. We conclude that the change in GABAergic function, and possibly the Ca2+ homeostasis, in SCN neurons may contribute to the altered synchrony within the aged SCN network.

Pharmacological Regulation of Endoplasmic Reticulum Structure and Calcium Dynamics: Importance for Neurodegenerative Diseases.

The endoplasmic reticulum (ER) is the largest organelle of the cell, composed of a continuous network of sheets and tubules, and is involved in protein, calcium (Ca2+), and lipid homeostasis. In neurons, the ER extends throughout the cell, both somal and axodendritic compartments, and is highly important for neuronal functions. A third of the proteome of a cell, secreted and membrane-bound proteins, are processed within the ER lumen and most of these proteins are vital for neuronal activity. The brain itself is high in lipid content, and many structural lipids are produced, in part, by the ER. Cholesterol and steroid synthesis are strictly regulated in the ER of the blood-brain barrier protected brain cells. The high Ca2+ level in the ER lumen and low cytosolic concentration is needed for Ca2+-based intracellular signaling, for synaptic signaling and Ca2+ waves, and for preparing proteins for correct folding in the presence of high Ca2+ concentrations to cope with the high concentrations of extracellular milieu. Particularly, ER Ca2+ is controlled in axodendritic areas for proper neurito- and synaptogenesis and synaptic plasticity and remodeling. In this review, we cover the physiologic functions of the neuronal ER and discuss it in context of common neurodegenerative diseases, focusing on pharmacological regulation of ER Ca2+ Furthermore, we postulate that heterogeneity of the ER, its protein folding capacity, and ensuring Ca2+ regulation are crucial factors for the aging and selective vulnerability of neurons in various neurodegenerative diseases. SIGNIFICANCE STATEMENT: Endoplasmic reticulum (ER) Ca2+ regulators are promising therapeutic targets for degenerative diseases for which efficacious drug therapies do not exist. The use of pharmacological probes targeting maintenance and restoration of ER Ca2+ can provide restoration of protein homeostasis (e.g., folding of complex plasma membrane signaling receptors) and slow down the degeneration process of neurons.

PO-01-217 FUNCTIONAL CHARACTERIZATION OF CALCIUM HANDLING KINETICS IN RE-ENGINEERED CARDIOMYOCYTES FROM A PATIENT WITH TYPE 2 LONG QT SYNDROME

Type 2 long QT syndrome (LQT2) is caused by pathogenic variants in the KCNH2-encoded Kv11.1 K+ channel resulting in prolongation of the action potential duration (APD) at the cellular level and QT prolongation in the patient, predisposing LQT2 patients to potentially lethal ventricular arrhythmias. Limited evidence, namely prolonged Ca2+ transient in human induced pluripotent stem cell derived cardiomyocytes (iPSC-CMs) and enhanced Ca2+ leak in transgenic LQT2 rabbit model, suggests that KCNH2 pathogenic variants may be associated with perturbations in intracellular Ca2+ handling. To characterize the APD and Ca2+ handling properties of an iPSC-CM model of LQT2. iPSC-CMs were generated from a patient with a pathogenic KCNH2 frame-shift variant (p.Q901fs/71) and an unrelated healthy control. Confocal imaging of FluoVolt voltage dye was used to measure the APD at 90% repolarization (APD90) in iPSC-CMs. Ca2+ kinetics was characterized using Ca2+ sensing dye Fluo4-AM before and after treatment with 100 nM isoproterenol (ISO). Q901fs/71-iPSC-CMs had a significantly prolonged APD90 compared to wild-type (WT) iPSC-CMs (444 ±9 ms vs 631±8 ms, p<0.001). Q901fs/71-iPSC-CMs had a higher Ca2+ amplitude (DF/F0) before (0.423±0.043 vs 0.97±0.07, p=0.001) and after ISO treatment (0.602±0.051 vs 1.056 ±0.06, p<0.001) compared to WT. The Ca2+ transient duration (CTD90) was longer in Q901fs/71-iPSC-CMs than in WT before (1.062±0.041 s vs 1.306±0.038 s, p=0.01), but not after ISO (1.071±0.062 s vs 1.092±0.044 s, p=0.96). Peak to 90% Ca2+ decay time was increased in Q901fs/71-iPSC-CMs before (0.785±0.04 s vs 0.942±0.033 s, p=0.028), but not after ISO (0.748±0.054 s vs 0.767±0.038 s, p=0.95). Upstroke time was longer in Q901fs/71-iPSC-CMs compared to WT before (0.281±0.006 s vs 0.364±0.014 s; p=0.002) but not after ISO (0.327±0.014 s vs 0.344±0.025 s; p=0.88). Upstroke velocity (DF/F0/t) was increased in Q901fs/71-iPSC-CMs before (1.092±0.122 vs 2.278±0.278, p<0.001) and after ISO (1.310±0.117 vs 2.2±0.139, p=0.005). Ca2+ leak from sarcoplasmic reticulum was higher in Q901fs/71-iPSC-CMs before (16% vs 38%) and after ISO (16% vs 55%). We show that iPSC-CMs derived from the patient with a truncating LQT2-causative variant (yielding likely Kv11.1 channel haploinsufficiency) have prolonged APD90 and display abnormal Ca2+ handling properties such as higher amplitude, increase in Ca2+ leak, prolonged transient duration, Ca2+ decay time, and upstroke velocity compared to WT iPSC-CMs.