Increase In Ca Concentration Research Articles

Agronomic bio-fortification and quality enhancement in okra–pea cropping system through arbuscular mycorrhizal fungi at varying phosphorus and irrigation regimes in Himalayan acid alfisol

ABSTRACTA field experimentation was conducted during 2009-2011 at CSK Himachal Pradesh Agricultural University, Palampur, India characterized with wet-temperate climate and acid Alfisol soil having medium available phosphorus content. The study aimed at bio-fortification and quality enhancement of okra (Abelmoschus esculentus)–pea (Pisum sativum) cropping system through arbuscular mycorrhizal fungi (AMF) (Glomus mosseae) at varying inorganic phosphorus (50, 75, and 100% soil-test-based recommended P dose) and irrigation regimes (40 and 80% available water capacity) in a Himalayan acid Alfisol. The results revealed that AMF and inorganic P significantly enhanced the concentrations and uptake of various primary [nitrogen (N), phosphorus (P), and potassium (K)]; secondary [calcium (Ca)]; and micronutrients [iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), boron (B), and molybdenum (Mo)] in okra and pea crops. However, effects of varying irrigation regimes were found to be nominal. In okra, AMF inoculation considerably enhanced N, P, K, B, and Mo uptake by 5, 19, 3, 4, and 15%, respectively, over their non-AMF counterparts. Likewise in pea, a higher amount of N (10%), P (26%), K (7%), Fe (7%), Cu (38%), Zn (20%), Mn (4%), B (7%), and Mo (13%) uptake was registered through AMF inoculation over their non-AMF counterparts. Application of soil-test-based P dose from 50% to 100% P also resulted in significant and consistent improvement in N, P, K, B, and Mo uptake both in okra and pea and in Zn, Cu, Mn, and Fe uptake in pea crop. Magnitude of increase in Ca content was to the tune of 13 and 4%, respectively, in okra fruits and pea pods following AMF inoculation, whereas crude protein content enhanced by 4% each in both the crops. Overall, the current study demonstrates the important role of AMF in nutrient enrichment and quality enhancement of okra and pea crops in acid Alfisol, besides considerable reduction in investment on chemical fertilizers. Results of current study suggest that AMF use in Himalayan production systems is of tremendous significance to harvest nutritionally-rich farm produce for Himalayan communities suffering from malnutrition especially anemia and Zn deficiency, and equally to resource-poor Himalayan farmers who ill-afford expensive external inputs.

Dehydration of 2‐Octanol over Ca‐doped CeO2 Catalysts

AbstractVapor‐phase catalytic dehydration of 2‐octanol was investigated over Ca‐doped CeO2 at 375 °C and atmospheric pressure. Ca doping up to 0.15 wt % was found to increase the dehydration activity for 2‐octanol, whereas further increases in Ca content (0.50 and 1.25 wt %) detrimentally affected the conversion. Catalyst surface area and pore volume increased with increasing Ca content in Ca‐doped CeO2. Hydrogen temperature‐programmed reduction (TPR) profiles indicate that the partially reduced state of surface ceria (i.e., Ce3+), which increases with increasing Ca loading up to 0.15 wt %, might play an important role in promoting dehydration.

Enhancement of temperature coefficient of resistance (TCR) and Magneto-resistance (MR) in La1–x Ca x MnO3:Ag0.2 polycrystalline composites

La1−x Ca x MnO3 (x ranges from 0.28 to 0.34) ceramics with Ag addition were synthesized by sol–gel method using methanol as solvent. The EDS elemental mapping shows that Ag element was detected dominantly on the sample surface. The sample of x = 0.28 has almost no pore and bigger grain size, which indicated that it has better crystallization and high density. Temperature dependence of resistivity shows that the samples for all Ca content exhibit sharp metal–insulator transition, and the corresponding metal–insulator temperature shift toward higher temperature with increasing Ca content. The temperature coefficient of resistance value for x = 0.28 reaches its the highest value, 71.8%·K−1. This temperature coefficient of resistance value is even higher than the previously reported for LCMO films and single crystals, and it shows a very promising application for the infrared and bolometric detectors. The high magnetoresitance for x = 0.28 reaches up to 69.3% in magnetic field of 1 T near room temperature. It was concluded that it improved the properties of LCMO:Ag composites are attributed to its improved crystallization by Ag addition, homogeneity and Mn4+/Mn3+ ratio. Different theoretical models are employed to analyze the resistance behaviors in different temperature regions, which give good agreements with experimental results.

Study of Ferroelectric and Piezoelectric Properties on Ca Doped PZT Ceramics

Pb1-xCaxZr0.52Ti0.48O3 ceramics with x = 0.02, 0.04, 0.06 and 0.10 were prepared by the sol gel technique. Raman and FTIR studies of the sample show the presence of both tetragonal and rhombohedral phases of PZT. It also indicates the enhanced strain in the sample due to the different ionic size of Ca2+ and Pb2+. Polarization versus electric field loops of the sample reveals that, the remnant polarization and coercive field increases with the increase in Ca concentration. The maximum value of remnant polarization (Pr) and coercive field (Ec) were found to be 12.34 μC /cm2 and 10.27 kV/cm respectively for Pb0.90Ca0.10Zr0.52Ti0.48O3 sample. The piezoelectric coefficient of the sample was measured at room temperature at the different poling field and found to increase with the increase in poling field. The piezoelectric co-efficient of Pb0.90Ca0.10Zr0.52Ti0.48O3 sample is 274 pC/N. Hence, the calcium doping increases the piezoelectric co-efficient and ferroelectric properties of the sample.

Growth of Mg2Si crystals shaped by {100} and {111} facets from Al–Mg–Si melts in the presence of calcium

In this work, primary Mg2Si crystals shaped by {100} and {111} facets were successfully fabricated in Al–Mg–Si melts via the adsorption and poisoning of the Ca element. The modifier Ca plays an important role in determining the morphologies of primary Mg2Si, which can be transformed from dendrites (0 wt%) to crystals with a combination of eight {111} and four {100} facets (0.08 wt%), then to truncated cubes (0.1 wt%), and finally to cubes fully bounded by {100} facets (0.2 wt%) with increasing Ca content. The growth processes of cubic primary Mg2Si have been revealed. As the growth rates of {100} surfaces are diminished by adsorption of the Ca element, primary Mg2Si tends to form perfect cubes with exposed {100} facets. Moreover, by prudently adjusting the concentration of the Ca element, complex polyhedral crystals enclosed by {111} and {100} surfaces were designed and prepared. The results offer valuable insights into designing the modification effect of different modifying elements, which are critical to promoting the industrial application of light alloys with improved morphology and refined size of microstructures.

Demise of Ediacaran dolomitic seas marks widespread biomineralization on the Siberian Platform

Abstract The trigger for biomineralization of metazoans in the terminal Ediacaran, ca. 550 Ma, has been suggested to be the rise of oxygenation or an increase in seawater Ca concentration, but geochemical and fossil data have not been fully integrated to demonstrate cause and effect. Here we combine the record of macrofossils with early marine carbonate cement distribution within a relative depth framework for terminal Ediacaran to Cambrian successions on the eastern Siberian Platform, Russia, to interrogate the evolution of seawater chemistry and biotic response. Prior to ca. 545 Ma, the presence of early marine ferroan dolomite cement suggests dominantly ferruginous anoxic “aragonite-dolomite seas”, with a very shallow oxic chemocline that supported mainly soft-bodied macrobiota. After ca. 545 Ma, marine cements changed to aragonite and/or high-Mg calcite, and this coincides with the appearance of widespread aragonite and high-Mg calcite skeletal metazoans, suggesting a profound change in seawater chemistry to “aragonite seas” with a deeper chemocline. By early Cambrian Stage 3, the first marine low-Mg calcite cements appear, coincident with the first low-Mg calcite metazoan skeletons, suggesting a further shift to “calcite seas”. We suggest that this evolution of seawater chemistry was caused by enhanced continental denudation that increased the input of Ca into oceans so progressively lowering Mg/Ca, which, combined with more widespread oxic conditions, facilitated the rise of skeletal animals and in turn influenced the evolution of skeletal mineralogy.

The effect of iridium oxidation state on the electronic properties of perovskite-type solid solutions: Ba2–xLaxInIrO6 and BaLaIn1–yCayIrO6

Two novel solid solution series, Ba2-xLaxInIrO6 (x=0–1.0) and BaLaIn1-yCayIrO6 (y=0–1.0), were prepared and several changes in structure, moment and charge transport were observed. The Ba2-xLaxInIrO6 series exhibits a transition from a 6M polytype to an orthorhombic perovskite structure with increased La content whereas the BaLaIn1-yCayIrO6 series transitioned from a disordered, orthorhombic perovskite to an ordered, cubic perovskite with increased Ca content. Seebeck measurements for both systems showed that Ir(IV)-rich compounds tended to have a n-type conduction mechanism while Ir(V)-rich compounds tended to be p-type. Both systems were found to be semiconducting and the magnitude of the resistivity is dependent on crystal structure and Ir environment. Magnetic measurements show that the μeff values for both systems are significantly less than predicted for Ir(IV) (1.73 μB) and greater than predicted for Ir(V) (0 μB). These results are compared to other iridate compound families.

Effects of Alloying Element Ca on the Corrosion Behavior and Bioactivity of Anodic Films Formed on AM60 Mg Alloys.

Effects of alloying element Ca on the corrosion behavior and bioactivity of films formed by plasma electrolytic oxidation (PEO) on AM60 alloys were investigated. The corrosion behavior was studied by conducting electrochemical tests in 0.9% NaCl solution while the bioactivity was evaluated by soaking the specimens in simulated body fluid (SBF). Under identical anodization conditions, the PEO film thicknesses increased with increasing Ca content in the alloys, which enhanced the corrosion resistance in NaCl solution. Thicker apatite layers grew on the PEO films of Ca-containing alloys because Ca was incorporated into the PEO film and because Ca was present in the alloys. Improvement of corrosion resistance and bioactivity of the PEO-coated AM60 by alloying with Ca may be beneficial for biodegradable implant applications.

Additive toxicity of zinc and arsenate on barley (Hordeum vulgare) root elongation.

Zinc (Zn) and arsenic (As) are typically present as mixed contaminants in mining-impacted areas; however, their joined effects have rarely been evaluated. The present study was set up to test whether the Zn2+ and H2 AsO4- (hereafter, As) mixture toxicity to plants is additive or whether interactions occur. Barley (Hordeum vulgare) root elongation was measured in resin buffered nutrient solutions. The design included ranges of single-element concentrations and combinations at 3 different Ca2+ concentrations (0.5 mM, 2.2 mM, and 15.0 mM) to vary the relative toxicity of Zn2+ . Increasing Ca concentrations decreased Zn toxicity, whereas As toxicity was unaffected by Ca. Root elongation was generally more affected in Zn-As mixtures than in corresponding single-element treatments. This is merely a joint additive effect, as 96% of the root elongation data were within a factor of 1.2 from predictions using the independent action (IA) or concentration addition (CA) model. The CA and IA predictions were similar, and data did not allow identification of equal or dissimilar modes of action. Small but significant Zn-As antagonisms were only found at high effects (>50% inhibition). The present study suggests that mixture effects of Zn and As are environmentally relevant and that current risk assessment underestimates toxicity in multielement-contaminated environments. The CA model can be used as a conservative model for risk assessment; however, for soil-grown plants, soil-exposed studies are needed. Environ Toxicol Chem 2017;36:1556-1562. © 2016 SETAC.

Monitoramento de água e sedimento no Rio Palmeiras, Bacia Hidrográfica do Tubarão (SC), Brasil

RESUMO A mineração de carvão na Bacia Carbonífera Catarinense causa poluição dos recursos hídricos. O objetivo do estudo foi caracterizar a água e o sedimento do Rio Palmeiras, na Bacia Hidrográfica do Tubarão, pela quantificação de metais na água em espectrômetro de massa com fonte de plasma indutivamente acoplado (ICP-MS) e no sedimento em espectrometria de absorção atômica de alta resolução com fonte contínua (HR-CS AAS), e outras variáveis, relacionadas à mineração de carvão. Na água, ocorreu aumento das concentrações de Ca, Mg, Fe, Al, Mn, Zn, e Pb, e no sedimento, ocorreu a diminuição das concentrações de Al, Mn, Zn, Cu e Pb em função da mineração de carvão, propiciada pela solubilização devida ao baixo pH da água. Observaram-se correlações entre as concentrações dos metais na água, no sedimento e cruzadas entre os teores na água e no sedimento.

Evidence of mixed valence Cr $$^{+3}$$ + 3 /Cr $$^{+4}$$ + 4 in Y $$_{1-x}$$ 1 - x Ca $$_x$$ x CrO $$_3$$ 3 polycrystalline ceramics by X-ray photoelectron spectroscopy

Y $$_{{1-x}}$$ Ca $$_{x}$$ CrO $$_{3}$$ polycrystalline ceramics with 0.000 $$\le $$ x $$\le $$ 0.100 compositions were studied by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results revealed that the $$\langle $$ Cr–O $$\rangle $$ average bond length decreases with increasing Ca content. This fact infers that the charge compensation is through the change from Cr $$^{+3}$$ to Cr $$^{+4}$$ instead of oxygen vacancies. To confirm this supposition, the high-resolution XPS study revealed that as the Ca is introduced in the YCrO $$_{3}$$ matrix, the Cr 2p $$_{{3/2}}$$ core-level is well fitted at 576.22 and 577.57 eV belonging at Cr $$^{+3}$$ and Cr $$^{+4}$$ core-level, respectively. Furthermore, we found an increase of the valence band XPS spectra at the Fermi energy as the Ca replaces the Y site. This fact suggests an increase of the Cr 3d-state at the Fermi energy, which is confirmed by the XPS valence band spectra and the electrical conductivity measurements.

Enhanced Electrical Resistivity and Soft Magnetic Properties in Ca-Doped Fe-B-Cu Alloy Ribbons

Fe83.5B15Cu1.5Cax (x= 0.04, 0.07, 0.1 and 0.13) alloy ribbons were fabricated by melt spinning. The effects of Ca addition on electrical resistivity and soft magnetic properties were investigated. The results show that with increasing Ca content from 0.04 to 0.13 the electrical resistivity monotonously increases from 0.51 μΩ·m to 0.99 μΩ·m while the core loss reduced by 39% and 28% at 10 kHz and 20kHz under an applied magnetic field of 200 mT, respectively. After annealing at 420°C for 10min, sample with x=0.13 obtains the peak saturation induction density (Bs) of 1.82 T and coercive force (Hc) of 18 A/m. Especially, the core loss of sample x=0.13 decreased by 13% and 34% than that of x= 0.04 at 200 kHz under an applied magnetic field of 25 mT and 50 mT respectively. Therefore, the soft magnetic properties and core loss can be tuned by addition of Ca in Fe-B-Cu alloy ribbons.

Photoluminescence of CaxBa1−xGa2S4:Eu2+ solid solutions in wide excitation intensity and temperature intervals

The detailed investigation of CaxBa1−xGa2S4:Eu2+ solid solutions photoluminescence caused by 5d→4f electronic transitions in Eu2+ ions with x value from 0.1 to 0.9 in wide excitation intensity and temperature intervals was performed. It is shown that the change of x from 0.1 to 0.9 appears in a tune of emission spectrum peak position from 506nm to 555nm with minimal losses in the integral intensity not more than by 8%. The long wavelength shift of the emission spectra was determined as a result of the rise in the crystal field splitting energy of 5d-orbitals of Eu2+ ions in thiogallate host with increasing Ca content, which decreases the energy of the 5d→4f emission transition. The energies of the zero phonon line, red shift and the Stokes shift were defined for x value from 0.1 to 0.9. High temperature stability of the integral emission intensity with a decrease at only 25–40% depending on x value was found in the range from 10K to 400K. It was revealed that the increase in Ca content leads to a reduction of the temperature shift of the emission spectrum whereas at x≥0.5 the shift is absent. The photoluminescence decay time constants were found to be from 305ns to 470ns for x value from 0.1 to 0.9. The extreme stability of the emission band shape and spectral position was found in a wide range of excitation power density from 10−3W/cm2 to 107W/cm2 with a reversable emission efficiency droop only above 2·104W/cm2.

Assessing the geologic evolution of Greater Thaumasia, Mars

AbstractThe Greater Thaumasia region consists of three chemical provinces that include Syria, Solis, and Thaumasia Planae, the Corprates Rise, part of the Thaumasia Highlands, and the transition zone northwest of the Argyre basin. Chemical signatures obtained from the Mars Odyssey Gamma Ray Spectrometer suggest low abundances of K and Th to the west, with low H abundances and high Si abundances to the east, relative to the bulk Martian crust at midlatitudes. These observations are confirmed and quantified with a modified box and whisker analysis that simultaneously captures the degree of deviation and significance of the regionally anomalous chemistry. Motivated by regionally unique chemistry, as well as its diverse geological history, we characterize Greater Thaumasia in terms of chemistry, mineralogy, and mapped geology to determine how such complementary data record the evolution of this region. Our observations are inconsistent with a proposed salt‐lubricated landslide origin, particularly given the lack of chemical or mineralogical signatures to support near‐surface salt deposits that should arise over geological timescales. Our observations instead support magmatic processes, such as mantle evolution over geological time, which may impart the Si‐enriched signature of the eastern portion of Greater Thaumasia as well as the K and Th depletion of the southeastern flank of Syria Planum. While the observed trend of decreasing K and Th from Noachian to Hesperian lavas is inconsistent with previous models of Martian mantle evolution, we see an increase in Ca content at the Noachian‐Hesperian boundary, consistent with predictions from thermodynamic modeling.

Application of Sugar Foam to Vineyard Acid Soils under Mediterranean Conditions

Calcium (Ca) deficiency and aluminium (Al) toxicity are considered major chemical constraints that limit vine growth in vineyard acid soils under Mediterranean conditions. The main aim of this work was to evaluate the effects of three doses of sugar foam (900, 1 800 and 2 700 kg CaCO3/ha) on five soil properties (pH in water, Ca, Mg, K and Al exchangeable contents) and Ca concentrations in petioles and canes of one wine grape variety. Research was conducted over three seasons (2006 to 2008) in a random block design at Leon (Spain). The results for plants and soils were subjected to general lineal model analysis. As a result, one linear model, validated through a cross-validation procedure, has been proposed to predict exchangeable calcium levels in vineyard acid soils at veraison. Based on the results for the soils, the higher doses of sugar foam (1 800 and 2 700 kg CaCO3/ha) were the most effective doses in decreasing Al exchangeable and increasing Ca exchangeable contents. In addition, liming increased Ca content in petioles and decreased Ca content in canes, but in both cases these differences were not significant.

Characterizing Clinoptilolite Zeolite and Hydroaluminosilicate Aggregates for Ammonium Removal from Stormwater Runoff

AbstractAmmonium is a nitrogen species that can directly enter a stormwater control measure (SCM) or be produced from degradation of organic nitrogen available in stormwater runoff. Clinoptilolite zeolite (ZT) and a hydrous aluminosilicate (CA) were investigated for ammonium removal use in filtration-based SCMs. Sorption capacity, kinetics, and strength of attachment were completed in batch settings. For the four different background electrolytes tested at neutral pH, ZT showed the highest uptake, particularly at 0.03 M NaCl, followed by 0.01 M CaCl2. The lowest uptake was found to occur for K+ electrolytes. Kinetics of ammonium uptake was also found to be more rapid for ZT (i.e., 30 min for ZT and 240 min for CA), and increase in concentrations of Ca2+ and K+ slowed the sorption process from 30 to 240 min. Extraction studies indicated high extractability of ammonium in ZT, while CA showed slightly smaller extractable ammonium; the results suggest that ammonium removed by CA is less exchangeable and possi...

Phase evolution of C-(N)-A-S-H/N-A-S-H gel blends investigated via alkali-activation of synthetic calcium aluminosilicate precursors

Stoichiometrically-controlled alkali-activated pastes containing calcium-(sodium) aluminosilicate hydrate (C-(N)-A-S-H) and sodium aluminosilicate hydrate (N-A-S-H) gels are produced by alkali-activation of high-purity synthetic calcium aluminosilicate powders. These powders are chemically comparable to the glass in granulated blast furnace slag, but without interference from minor constituents. The physiochemical characteristics of these gels depend on precursor chemical composition. Increased Ca content of the precursor promotes formation of low-Al, high-Ca C-(N)-A-S-H with lower mean chain length as determined by quantification of solid state nuclear magnetic resonance spectra, and less formation of calcium carboaluminate ‘Alumino-ferrite mono’ (AFm) phases. Increased Al content promotes Al inclusion and reduced crosslinking within C-(N)-A-S-H, increased formation of calcium carboaluminate AFm phases, and formation of an additional N-A-S-H gel. Small changes in precursor composition can induce significant changes in phase evolution, nanostructure and physical properties, providing a novel route to understand microstructural development in alkali-activated binders and address key related durability issues.

Environmental History of Mangrove Vegetation in Pacific West-Central Mexico during the Last 1300 Years

Abstract Mangroves are a highly threatened ecosystem due to climate change and human activity, which increases coastal vulnerability. Knowledge about the ecological dynamics of mangroves on a centennial timescale can reveal the different responses in vegetation, which is useful for implementing basic actions for mangrove restoration, conservation and management. A mangrove ecosystem in the Cuyutlan Lagoon area along the Pacific coast of west-central Mexico is significantly altered as a result of industrialization, salt extraction, and road construction. The long-term dynamics of the mangrove ecosystem has also been controlled by Holocene climatic variability. This study reconstructs the environmental history of mangrove vegetation around the Cuyutlan Lagoon during the last ~1300 years in response to periods of human activity and climate change. The reconstruction was performed using paleoecological techniques in sediment cores that include the use of fossil pollen as a proxy for vegetation and magnetic susceptibility and geochemical data (determined by loss-on-ignition and X-ray fluorescence) as a proxy for past environmental changes. The chronology was determined using 14C dating and the age-depth model was constructed by linear interpolation. Redundancy analysis and non-metric multidimensional scaling (NMDS) were used to discern patterns of distribution of the different proxies. Results revealed that the mangrove pollen assemblage of the Cuyutlan Lagoon was dominated by the arboreal taxa Rhizophora mangle, Euphorbiaceae, Moraceae and Pinaceae, herbaceous taxa like Poaceae, Chenopodiaceae/Amaranthaceae, and aquatics such as Typhaceae and Cyperaceae. NMDS showed a clear separation between two events of human activity—the Spanish Occupation of Colima (~AD 1523-1524) and the opening of the Manzanillo port (~AD 1824-1825). Climate change events such as the Medieval Climate Anomaly (MCA) (~AD 800-1200) and the Little Ice Age (LIA) (~AD 1350-1850) were also successfully identified. The main responses were mangrove expansion (driven by R. mangle) during the LIA and the Manzanillo Port Opening, while the MCA was a highly perturbed period marked by multiple hurricane events and low or no pollen deposition in the sediment. During the Spanish Occupation, the aquatic taxa Typhaceae expanded together with an increase in Ca, Sr and carbonate contents.

Exploring IRSL50 fading variability in bedrock feldspars and implications for OSL thermochronometry

Optically Stimulated Luminescence (OSL) is a well-established Quaternary dating method, which has recently been adapted to application in low-temperature thermochronometry. The Infra-Red Stimulated Luminescence (IRSL) of feldspar, which so far is the most promising target signal in thermochronometry, is unfortunately prone to anomalous fading. The fading of feldspar IRSL is at times not only challenging to measure, but also laborious to incorporate within luminescence growth models. Quantification of IRSL fading is therefore a crucial step in OSL thermochronometry, raising questions regarding (i) reproducibility and reliability of laboratory measurements of fading, as well as (ii) the applicability of existing fading models to quantitatively predict the level of IRSL field saturation in nature. Here we investigate the natural luminescence signal and anomalous fading of IRSL measured at 50 °C (IRSL50) in 32 bedrock samples collected from a variety of lithologies and exhumation settings (Alaska and Norway). We report a large span of IRSL50 fading rates between samples (g2days ranging from ∼0.5 to ∼45%/decade), which further demonstrates (i) a good reproducibility between two common fading measurement protocols, and (ii) the ability of tunnelling models to predict the level of feldspar IRSL50 field saturation in nature. We observe higher IRSL50 fading in feldspar with increasing Ca content, although other factors cannot be dismissed at present. Finally, our dataset confirms that the applicability of feldspar IRSL50 in OSL thermochronometry is limited to rapidly-exhuming settings or warm subsurface environments.

MGluR1 and mGluR5 Synergistically Control Cholinergic Synaptic Transmission in the Thalamic Reticular Nucleus.

Acetylcholine (ACh) signaling is involved in a wide range of processes, including arousal, attention, and learning. An increasing number of studies indicate that cholinergic control of these functions is highly deterministic, mediated by synaptic afferents that generate reliable and precise responses in postsynaptic neurons. However, mechanisms that govern plastic changes of cholinergic synaptic strength are poorly understood, even though they are likely critical in shaping the impact of cholinergic inputs on neuronal networks. We have recently shown that in the thalamic reticular nucleus (TRN), synaptic release of ACh generates excitatory-inhibitory biphasic postsynaptic responses, mediated by the activation of α4β2 nicotinic (nAChRs) and M2 muscarinic receptors (mAChRs), respectively. Here, using voltage-clamp recordings from TRN neurons in thalamocortical slices of mice, we demonstrate that the activation of Group I metabotropic glutamate receptors (mGluRs) by ambient or synaptically released glutamate evokes transient increases of nicotinic EPSCs. Additionally, we find that the selective Group I mGluR agonist DHPG [(S)-3,5-dihydroxyphenylglycine] evokes long-term potentiation of nicotinic EPSCs (mGluR-nLTP), dependent on increases in postsynaptic Ca(2+) concentration and the activation of phospholipase C. Both the induction and the maintenance of mGluR-nLTP require synergistic activation of mGluR1 and mGluR5. Together, our results show that postsynaptic Group I mGluRs are critically involved in the regulation of cholinergic synaptic strength on different time scales, suggesting that cholinergic control of local thalamic circuits is highly context-dependent and regulated by the overall levels of glutamatergic afferent activity. Cholinergic signaling controls information processing and plasticity in neuronal circuits, but the mechanisms underlying the regulation of cholinergic synaptic strength on different time scales are unknown. Here we identify mGluR1 and mGluR5 as key elements in the dynamic regulation of cholinergic synaptic inputs onto neurons of the TRN. Our findings highlight potential mechanisms that regulate cholinergic signaling in the mammalian brain.