Search results for "Calcium"

Element variability in the coralline alga Lithophyllum yemenense as archive of past climate in the Gulf of Aden (NW Indian Ocean)

2017

This study presents the first algal thallus (skeleton) archive of Asian monsoon strength and Red Sea influence in the Gulf of Aden. Mg/Ca, Li/Ca, and Ba/Ca were measured in Lithophyllum yemenense from Balhaf (Gulf of Aden) using laser ablation inductively coupled plasma mass spectrometry, and Mg/Ca ratio oscillation was used to reconstruct the chronology (34 y). Oscillations of element rates corresponding to the algal growth between 1974 and 2008 were compared with recorded climate and oceanographic variability. During this period, sea surface temperatures (SST) in Balhaf recorded a warming trend of 0.55 degrees C, corresponding to an increase in Mg and Li content in the algal thallus of 2.…

Portlandite solubility and Ca 2+ activity in presence of gluconate and hexitols

2021

The current paper investigates the impact of gluconate, D-sorbitol, D-mannitol and D-galactitol on calcium speciation at high pH values by i) solubility measurements of portlandite (Ca(OH)2) and ii) potentiometric titration measurements of calcium salt solutions. Thermodynamic modeling was used to fit the chemical activities of Ca2+ and OH- ions and thus to determine the strength and kind of the different Ca-organic-hydroxide complexes. The strength of complex formation with Ca decreases in the order gluconate >> sorbitol > mannitol > galactitol, which follows the same order as sorption on portlandite. Heteropolynuclear gluconate complexes with calcium and hydroxide dominate the…

Interaction of CaSO4 with water vapour at high relative humidity

2010

16 pages. Prepublication en attente d'un complément expérimental; Soluble anhydrite β-CaSO4 reacts with water vapour at room temperature to form CaSO4-0.5H2O at 20-30% RH and CaSO4-0.6H2O at 70-80% RH. At higher RH, additional water uptake can only add-up to an adsorbed water layer. The present work provides evidence that a small amount of the adsorbent dissolves in the adsorbed layer and gypsum starts precipitating at 97-98 %RH even though condensation of the vapour phase does not take place. After several days the adsorbent is almost entirely and irreversibly converted. The kinetics of weight gain clearly discriminates between adsorption and dissolution-precipitation. If a minute amount o…

Monitoring a Mechanochemical Reaction Reveals the Formation of a New ACC Defect Variant Containing the HCO 3 – Anion Encapsulated by an Amorphous Mat…

2020

Crystal growth & design 20(10), 6831 - 6846 (2020). doi:10.1021/acs.cgd.0c00912

The shell matrix and microstructure of the Ram's Horn squid: Molecular and structural characterization.

2020

20 pages; International audience; Molluscs are one of the most diversified phyla among metazoans. Most of them produce an external calcified shell, resulting from the secretory activity of a specialized epithelium of the calcifying mantle. This biomineralization process is controlled by a set of extracellular macromolecules, the organic matrix. In spite of several studies, these components are mainly known for bivalves and gastropods. In the present study, we investigated the physical and biochemical properties of the internal planispiral shell of the Ram's Horn squid Spirula spirula. Scanning Electron Microscope investigations of the shell reveal a complex microstructural organization. The…

Calcium, calmodulin-dependent protein phosphorylation in Neurospora crassa

1984

Abstract A calcium, calmodulin-dependent protein kinase activity has been partially purified by calmodulin-Sepharose affinity chromatography from the soluble fraction of Neurospora crassa . The phosphorylated peptide has an apparent molecular mass on SDS-polyacrylamide gel of 47 kDa. The apparent half maximal phosphorylation is obtained after 1.5 min at 30° C in the presence of calcium and calmodulin. The apparent half maximal activation of the phosphorylation is obtained at 1 μM calcium, and 0.1 or 0.2 μM calmodulin from bovine brain or Neurospora , respectively. The 32 P incorporation is enhanced about 10-fold by calmodulin.

Localization of biomineral proteins by Atomic Force Microscopy (AFM) with functionalized tips

2021

Fatty Acid Smell, Anesthesia, and Use on Fruit Crops

2023

Odors convey important information to select a sex partner, to find a food source, or to detect a danger. Among those some volatile molecules have been shown to cause a reversible anesthesia. However, their mode of action appears still largely mysterious. Here we describe a novel property of Olfactory Receptor 47b (OR47b), on olfactory sensory neurons (OSNs) expressing male-specific transcription factor FruM. We found some interesting properties of a fatty acid that can be present on food sources and oviposition sites for Drosophilid species. We show that OR47b neurons projecting to VA1v glomerulus are sensitive to this odor, and that this influences Drosophila behavior causing a strong ave…

Involvement of reactive oxygen species in glucose sensitivity of hypothalamic neuron

2013

Zizyphin modulates sugar and fat taste perception: evidence from behavioural and calcium signaling studies

2016

IF 4.066; International audience