Sequence Of Ca2 Research Articles

Synthesis and characterization of ion-induced sodium alginate/soy protein isolate microgels for the controlled release

In this study, sodium alginate/ soy protein isolate (SPI) microgels cross-linked by various divalent cations including Cu2+, Ba2+, Ca2+, and Zn2+ were fabricated. Cryo-scanning electron microscopy observations revealed distinctive structural variations among the microgels. In the context of gastric pH conditions, the degree of shrinkage of the microgels followed the sequence of Ca2+ > Ba2+ > Cu2+ > Zn2+. Meanwhile, under intestinal pH conditions, the degree of swelling was ranked as Zn2+ > Ca2+ > Ba2+ > Cu2+. The impact of these variations was investigated through in vitro digestion studies, revealing that all microgels successfully delayed the release of β-carotene within the stomach. Within the simulated intestinal fluid, the microgel cross-linked with Zn2+ exhibited an initial burst release, while those cross-linked with Cu2+, Ba2+, or Ca2+ displayed a sustained release pattern. This research underscores the potential of sodium alginate/SPI microgels cross-linked with different divalent cations as efficient controlled-release delivery systems.

Hydrogeochemical characterization and evaluation of subsurface water quality in the Proterozoic Cuddapah Basin, Andhra Pradesh, India.

In the current survey, different hydrogeochemical processes governing the geochemistry of aquifers, the usefulness of groundwater for regular consumption, and agricultural purposes were evaluated around the Tummalapalle area. One hundred forty-four borehole locations were chosen to characterize the major physicochemical components of the aquifer water. The analysis results of pH inferred that the groundwater is nominally acidic to basic, and pH ranged from 6.6 to 8.4. The average concentrations of TDS, Ca2+, Mg2+, total hardness (TH), HCO3-, and total alkalinity (TA) are within the allowable limits of potable water quality as prescribed by the Bureau of Indian Standards (BIS) and WHO. However, the average concentrations of Na+, K+, Cl-, and SO42- were all below the permissible limit. All samples were analyzed with the help of Piper and Chadha charts to determine the dominant hydrogeochemical components of groundwater. The dominance of cations in groundwater in this region is in the sequence of Ca2+ > Na+ > Mg2+ > K+, followed by anions HCO3- > Cl- > SO42-. The Gibbs plot analysis suggested the predominance of rock aquifer interaction as the major hydrogeochemical process governing groundwater geochemistry in this region.The water quality index (WQI) of all groundwater samples in the Tummalapalle region was estimated, with 55% of the samples being potable grade. The different irrigation indices were analyzed for the groundwater samples to estimate their desirability for agriculture. The maximum number of water samples was found to be well-suited for cultivation.

Assessment of groundwater geochemistry and human health risk of an intensively cropped alluvial plain, NW Italy

Groundwater chemistry data play an essential role to identify the water quality status and assess the exposure to human health. Therefore, in the present research, combined approaches used to assess the geochemistry, sources of ions and human health risk in the groundwater of the Tronzano Vercellese. Moreover, a geographic information system (GIS) technique was applied to identify locations have the most risk to human health. The results of the present study show that the groundwater samples had sequence of Ca2+>Mg2+>Na+>K+ in cationic, HCO3 −>SO4 2−>NO3 −>Cl−>F− in anionic and Zn > Fe > Ba > Ni > Mn > Cu > Cr > As in metals abundance. The hydrogeochemical approaches indicate that the major ions chemistry was mainly controlled by the weathering of carbonate and silicate minerals, and ion-exchange reactions. Furthermore, statistical analysis reveals that the non-lithogenic origin was the primary sources of some elements (Mn, Zn, Ba, NO3 − and K+) in the water samples. The hazard quotient (HQ) and hazard index (HI) were estimated to assess the risk to human health using the United States Environmental Protection Agency (USEPA) methods. Estimated HQ and HI values were higher for the child as compared to the adult and suggesting that the elements posed little hazard individually in the case of the child.

Functional Reconstitution of the Mitochondrial Ca2+/H+ Antiporter Letm1

The Letm1 (leucine zipper-, EF hand-containing transmembrane protein 1) gene encodes a mitochondrial inner membrane protein, whose depletion severely perturbs mitochondrial Ca2+ and K+ homeostasis. Here we expressed, purified, and reconstituted human Letm1 protein in liposomes. Using Ca2+ fluorophore and 45Ca2+ based assays, we demonstrate directly that Letm1 is a Ca2+ transporter, with apparent affinities of cations in the sequence of Ca2+ ≈ Mn2+ > Gd3+ ≈ La3+ > Sr2+ >> Ba2+, Mg2+, K+, Na+. Kinetic analysis yields a Letm1 turnover rate of 2 Ca2+/s and Km of ∼25 μM. Further experiments show that Letm1 mediates electroneutral 1 Ca2+/2 H+ antiport. Letm1 is insensitive to ruthenium red (RR), an inhibitor of the mitochondrial calcium uniporter (MCU), and CGP-37157, an inhibitor of the mitochondrial Na+/Ca2+ exchanger. Functional properties of Letm1 described here are remarkably similar to those of the H+-dependent Ca2+ transport mechanism identified in intact mitochondria.

Functional reconstitution of the mitochondrial Ca2+/H+ antiporter Letm1

The leucine zipper, EF hand–containing transmembrane protein 1 (Letm1) gene encodes a mitochondrial inner membrane protein, whose depletion severely perturbs mitochondrial Ca2+ and K+ homeostasis. Here we expressed, purified, and reconstituted human Letm1 protein in liposomes. Using Ca2+ fluorophore and 45Ca2+-based assays, we demonstrate directly that Letm1 is a Ca2+ transporter, with apparent affinities of cations in the sequence of Ca2+ ≈ Mn2+ > Gd3+ ≈ La3+ > Sr2+ >> Ba2+, Mg2+, K+, Na+. Kinetic analysis yields a Letm1 turnover rate of 2 Ca2+/s and a Km of ∼25 µM. Further experiments show that Letm1 mediates electroneutral 1 Ca2+/2 H+ antiport. Letm1 is insensitive to ruthenium red, an inhibitor of the mitochondrial calcium uniporter, and CGP-37157, an inhibitor of the mitochondrial Na+/Ca2+ exchanger. Functional properties of Letm1 described here are remarkably similar to those of the H+-dependent Ca2+ transport mechanism identified in intact mitochondria.

Biocalcification Mediated Reduction of PAHs Bioavailability in Artificially Contaminated Soil

Apart from natural CO2 sequestration, biocalcification process can reduce bioavailability of certain pollutants. In the present study, experiments were conducted to evaluate the change in bioavailability for three polycyclic aromatic hydrocarbons (PAHs) — anthracene (Ant), phenanthrene (Phe) and pyrene (Pyr) — either in normal soil extract that was spiked with PAHs (SESP) or spiked soil, after chemical calcification or biocalcification process. Results suggested that PAHs extractability in SESP (Ant: 2–4 mg/l, Phe: 3–6 mg/l and Pyr: 4.5–9 mg/l) after chemical precipitation of carbonate were not statistically different when compared to negative controls. However in biocalcification experiment the difference was statistically significant when conducted with SESP (P = 0.0425, α = 0.10) or soil (P = 0.035, α = 0.10). Supporting experiment revealed that the presence of microbial cells and sequence of Ca2+, CO3−2 addition was important in determining the extent in PAHs bioavailability reduction.

Molecular cloning and sequences analysis of parvalbumin gene in crucian carp and mandarin fish

Parvalbumin(PV) is the major allergen of fish species.So far,research concerning fish allergy has been focused mainly on marine fish.China is the largest consumer and producer of freshwater fish in the world,and many people suffered from allergy when consuming freshwater fish.Therefore,figuring out the molecular characters of PV from freshwater fish would be important.In this study,four gene sequences of PV isoforms were amplified and cloned from crucian carp and mandarin fish by RT-PCR,with two genes from each species.All the four genes were 330 bp in length,encoding 109 amino acid residues.The deduced molecular weight of them was approximately 11.6 ku,and isoelectric points were 4.45-4.69.The existence of amino acid residues of Ala-14,Leu-16,Cys-19,Phe-67,Gln-69 and Thr-79 suggested that all the sequences belonged to β-PV.The identity between the two sequences of crucian carp was 80.73 %,and was 83.49 % in mandarin fish.The identity between PVs from different fish species was higher than 75 % and the sequences of Ca2+binding sites were highly conserved.Phylogenetic tree based on some PV amino acid residues revealed that PVs are clustered into two major clades,teleost fish and other vertebrates.PVs of teleost were clustered into orthologous groups,suggesting duplication of the PV genes before the speciation of teleost while after the speciation of fish.The tertiary structures of these four PVs were constructed using SWISS-MODEL.They all contain three helix-loop-helix motifs named EF-hand.Two domains next to the C terminal were Ca2+ binding sites.These results may provide a molecular basis for further study on the allergen of fish PVs.

Standard Ion Index for Groundwater Quality Evolution

Spatial and temporal groundwater quality variations present distinctive characteristics for the hydrochemical composition of any aquifer. Hydrochemical characteristics of groundwater quality can be depicted by the standard ion index (SII). This is equivalent to the statistical standardization procedure, which is robust, assumption free and a dimensionless parameter with zero mean and unit standard deviation. Its application is suggested for eight major ion compositions (Ca2, Mg, Na, K, Cl2, HCO3, NO3, and SO4) in a given water sample. Individual and successive SII procedures are available, each with distinctive exposition of groundwater quality. Individual SII graphs expose standard ion values on the vertical ratio axis versus the nominal scale axis on the horizon in sequence of Ca2, Mg, Na, K, Cl2, HCO3, NO3, and SO4 variables for each sample. Successive SII graphs indicate the scatter of standard major ions values of one sample versus the next sample values. Theoretically two samples with the same hydrochemical composition yield scatter points that fall on the 45° straight-line, which is referred to as the “ideal similarity line” (ISL). In the successive SII graph the minimum ion concentrations take place at the lower end and the maximum concentrations at the upper end of the same line. Other ion clusters are aligned around the line depending on the groundwater quality composition. The application of this methodology is presented for a set of groundwater samples taken from a major well near Jeddah, Kingdom of Saudi Arabia, during 2000–2005 periods.

A new experimental model of focal seizures in the entorhinal cortex

Despite intensive studies, our understanding of the cellular and molecular mechanisms underlying epileptogenesis remains largely unsatisfactory. Our defective knowledge derives in part from the lack of adequate experimental models of the distinct phases that characterize the epileptic event, that is, initiation, propagation, and cessation. The aim of our study is the development of a new brain slice model in which a focal seizure can be repetitively evoked at a precise and predictable site. Epileptiform activities were studied by fast Ca²(+) imaging coupled with simultaneous single and double patch-clamp or extracellular recordings from neurons of entorhinal cortex (EC) slices from Wistar rats and C57BL6J mice at postnatal days 13-17. In the presence of 4-aminopyridine (4-AP) and low Mg²(+) , activation of layer V-VI neurons by local N-methyl-d-aspartate (NMDA) applications evolved into an ictal discharge (ID) that propagated to the entire EC. NMDA-evoked IDs were similar to spontaneous events. IDs with similar pattern and duration could be repetitively triggered from the same site by successive NMDA stimulations. The high ID reproducibility is an important feature of the model that allowed testing of the effects of currently used antiepileptic drugs (AEDs) on initiation, propagation, and cessation of focal ictal events. By offering the unique opportunity to repetitively evoke an ID from the same restricted site, this model represents a powerful approach to study the cellular and molecular events at the basis of initiation, propagation, and cessation of focal seizures.

Regulation of Inhibitory Synaptic Plasticity by Temporal Sequence of Ca2+ Signals in a Cerebellar Purkinje Neuron

Regulation of Inhibitory Synaptic Plasticity by Temporal Sequence of Ca2+ Signals in a Cerebellar Purkinje Neuron

Composition of Household Dust in Semi-urban Areas in Malaysia

A study of household dust composition was conducted in a semi-urban area around Kajang and Bandar Baru Bangi Selangor, Malaysia. Samples of household dust were collected from 31 randomly selected houses using a vacuum cleaner equipped with a changeable dust bag. Parameters analysed were anions (Cl-, SO4 2- , and NO3- ), cations (K+, Ca2+, and Mg2+), and heavy metals (Cd, Fe, Ni, and Pb) to deduce the possible sources and evaluate the toxicity of indoor dust. The concentration of each parameter was compared to the concentration of street dust collected outside the houses. The results showed that the composition of anions was dominated by Cl- followed by SO42- and NO 3-; cations concentration by the sequence of Ca2+ > K + > Mg2+ and for heavy metals concentration, Pb was present in the highest concentration followed by Ni > Fe > Cd > Zn. The study also showed that the concentration of most parameters analyzed were higher in household dust than street dust, suggesting that the composition of household dust is more closely related to indoor activities and the environment.

Induction of Abscisic Acid-Regulated Gene Expression by Diacylglycerol Pyrophosphate Involves Ca2+ and Anion Currents in Arabidopsis Suspension Cells

Diacylglycerol pyrophosphate (DGPP) was recently shown to be a possible intermediate in abscisic acid (ABA) signaling. In this study, reverse transcription-PCR of ABA up-regulated genes was used to evaluate the ability of DGPP to trigger gene expression in Arabidopsis (Arabidopsis thaliana) suspension cells. At5g06760, LTI30, RD29A, and RAB18 were stimulated by ABA and also specifically expressed in DGPP-treated cells. Use of the Ca2+ channel blockers fluspirilene and pimozide and the Ca2+ chelator EGTA showed that Ca2+ was required for ABA induction of DGPP formation. In addition, Ca2+ participated in DGPP induction of gene expression via stimulation of anion currents. Hence, a sequence of Ca2+, DGPP, and anion currents, constituting a core of early ABA-signaling events necessary for gene expression, is proposed.

Ca2+ Response to cADPr during Maturation and Fertilization of Starfish Oocytes

During the reinitiation of the meiotic cycle (maturation) induced by the hormone 1-methyladenine (1-MA), starfish oocytes undergo structural and biochemical changes in preparation for successful fertilization. Previous work has shown that the sensitivity of internal Ca2+ stores to InsP3 increases during maturation of the oocytes. Since Astropecten auranciacus oocytes also respond to cADPr, we have studied whether the response to cADPr also changes during maturation. We have found that the photoactivation of injected cADPr in immature oocytes immediately induces multiple patches of Ca2+ release in the cortical region. The Ca2+ signal then spreads from these initial points of increase to the entire cell. In mature oocytes, the uncaging of cADPr induces instead a single (or at most a dual) initial point of Ca2+ release, which is immediately followed by the formation of a cortical Ca2+ flash and then by the globalization of the wave and by the elevation of the fertilization envelope. External Ca2+ plays a role in the Ca2+ responses. Inhibition of L-type Ca2+ channels does not affect the initial Ca2+ release, but abolishes the cortical flash and impairs the elevation of the fertilization envelope. External Ca2+ has other effects, as shown by the irregular appearance of the surface of oocytes incubated in Ca2+-free sea water. The sequence of Ca2+ responses induced by cADPr in mature oocytes mimics those seen at fertilization, i.e., a first localized Ca2+ increase followed by a cortical flash and by the globalization of the Ca2+ signal. As in the case of maturation, L-type Ca2+ channel blockers abolish the sperm induced cortical flash.

The mechanism of alpha-adrenergic agonist action in liver.

Summary1. Although the mechanism of action of a‐adrenergic agonists in liver tissue is somewhat complex, a number of experimental approaches can be usefully employed to identify the molecular details of the events that occur.2. Receptors specific for α1‐adrenergic agonists located on the plasma membranes of rat liver cells have been partially characterized using pharmacological agents, affinity labels and monoclonal antibodies. Much of this work has employed isolated plasma membrane fractions and does not take account of tissue‐related factors which may now be studied in the intact perfused rat liver, following the development of an appropriate assay system.3. Because a redistribution of cellular Ca2+ is central to the mechanism of action of a‐adrenergic agonists in liver, it is important to first gain an understanding of basic cellular Ca2+ regulation. Knowledge about the compartmentation of cellular calcium and about Ca2+‐translocation systems located in the mitochondria, plasma membrane and endoplasmic reticulum is now quite extensive. However, the role of mitochondria in the regulation of intracellular Ca2+ is still unclear; it now appears that the mitochondrial calcium content is much less than considered previously. This may have important implications for such a regulatory role.4. The sequence of Ca2+ movements that may occur when a‐adrenergic agonists interact with liver have been identified and are as follows: (a) Ca2+ is mobilized from an intracellular pool(s) (mitochondria plus endoplasmic reticulum and/or plasma membranes). (b) This elevates the cytoplasmic free Ca2+ concentration and leads to an efflux of the ion from the cell. (c) At this time, Ca2+‐sensitive metabolic events in the cytoplasm are activated and an increase in Ca2+‐cycling occurs across the plasma membrane. (d) Immediately after the hormone is withdrawn, there is a net influx of Ca2+ into the cell, and the intracellular Ca2+ pools and transmembrane fluxes are restored to the pre‐induced states. In this model, Ca2+ movements across the plasma membrane play a key role in regulating the cytoplasmic Ca2+ concentration.5. In the perfused rat liver it has been possible to define in quite precise terms the amounts and rates of Ca2+ mobilized in each of these stages.6. Although several proposals for ‘second messengers’ to link the hormone‐receptor interaction with initial Ca2+ mobilization have been made, at this time only polyphosphoinositide turnover appears to be a suitable candidate.

Assimilation of Lime in the Formation of Calcium Aluminate from CaO and Al2O3

Mixes of CaCO3 and Al2O3 in the molar proportion of 3:1,1:1 and 1:2 respectively, were heated at different temperatures for various reaction times and the unreacted lime contents were determined. Phases formed in the reaction mixes have been studied by X-ray diffractograms of the partially reacted samples. Data show that lime is consumed in the three mixes before the equilibrium phase C3A, CA or CA2 is formed. The lime reactivity is in the sequence of CA2 < CA < C3A reaction mixes.*