Glycerol-3-phosphate acyltransferase 2 expression modulates cell roughness and membrane permeability: An atomic force microscopy study

In mammalian cells, de novo glycerolipid synthesis begins with the acylation of glycerol-3-phosphate, catalyzed by glycerol-3-phosphate acyltransferases (GPAT). GPAT2 is a mitochondrial isoform primarily expressed in testis under physiological conditions, and overexpressed in several types of cancers and cancer-derived human cell lines where its expression contributes to the tumor phenotype. Using gene silencing and atomic force microscopy, we studied the correlation between GPAT2 expression and cell surface topography, roughness and membrane permeability in MDA-MB-231 cells. In addition, we analyzed the glycerolipid composition by gas-liquid chromatography. GPAT2 expression altered the arachidonic acid content in glycerolipids, and the lack of GPAT2 seems to be partially compensated by the overexpression of another arachidonic-acid-metabolizing enzyme, AGPAT11. GPAT2 expressing cells exhibited a rougher topography and less membrane damage than GPAT2 silenced cells. Pore-like structures were present only in GPAT2 subexpressing cells, correlating with higher membrane damage evidenced by lactate dehydrogenase release. These GPAT2-induced changes are consistent with its proposed function as a tumor-promoting gene, and might be used as a phenotypic differentiation marker. AFM provides the basis for the identification and quantification of those changes, and demonstrates the utility of this technique in the study of cancer cell biology.Instituto de Investigaciones Bioquímicas de La PlataInstituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias ExactasFacultad de Ciencias Médica

Glycerol-3-phosphate acyltransferase 2 expression modulates cell roughness and membrane permeability: An atomic force microscopy study

In mammalian cells, de novo glycerolipid synthesis begins with the acylation of glycerol-3-phosphate, catalyzed by glycerol-3-phosphate acyltransferases (GPAT). GPAT2 is a mitochondrial isoform primarily expressed in testis under physiological conditions, and overexpressed in several types of cancers and cancer-derived human cell lines where its expression contributes to the tumor phenotype. Using gene silencing and atomic force microscopy, we studied the correlation between GPAT2 expression and cell surface topography, roughness and membrane permeability in MDA-MB-231 cells. In addition, we analyzed the glycerolipid composition by gas-liquid chromatography. GPAT2 expression altered the arachidonic acid content in glycerolipids, and the lack of GPAT2 seems to be partially compensated by the overexpression of another arachidonic-acid-metabolizing enzyme, AGPAT11. GPAT2 expressing cells exhibited a rougher topography and less membrane damage than GPAT2 silenced cells. Pore-like structures were present only in GPAT2 subexpressing cells, correlating with higher membrane damage evidenced by lactate dehydrogenase release. These GPAT2-induced changes are consistent with its proposed function as a tumor-promoting gene, and might be used as a phenotypic differentiation marker. AFM provides the basis for the identification and quantification of those changes, and demonstrates the utility of this technique in the study of cancer cell biology.Instituto de Investigaciones Bioquímicas de La PlataInstituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias ExactasFacultad de Ciencias Médica

The Eruption that Christopher Columbus observed in The Island of Tenerife (Canary Islands)

Geological field work, including detailed cartography and strict stratigraphic control together with radicarbon ages, have confirmed the historical date of the volcanic eruption that Christopher Columbus observed in the summits of the island of Tenerife in 1492. The last eruption of the Teide stratovolcano, known as the «Black Lavas» and repeatedly associated to this historical reference, has been definitively discarded in favour of Boca Cangrejo (Crab’s Mouth) volcano, located in the NW rift of the island, and which can thus be considered to be the fifth historical eruption of Tenerife, confirming the annotation written in the ship’s log of Christopher Columbus’s first voyage to Americ

Subcellular Location of PKA Controls Striatal Plasticity: Stochastic Simulations in Spiny Dendrites

Dopamine release in the striatum has been implicated in various forms of reward dependent learning. Dopamine leads to production of cAMP and activation of protein kinase A (PKA), which are involved in striatal synaptic plasticity and learning. PKA and its protein targets are not diffusely located throughout the neuron, but are confined to various subcellular compartments by anchoring molecules such as A-Kinase Anchoring Proteins (AKAPs). Experiments have shown that blocking the interaction of PKA with AKAPs disrupts its subcellular location and prevents LTP in the hippocampus and striatum; however, these experiments have not revealed whether the critical function of anchoring is to locate PKA near the cAMP that activates it or near its targets, such as AMPA receptors located in the post-synaptic density. We have developed a large scale stochastic reaction-diffusion model of signaling pathways in a medium spiny projection neuron dendrite with spines, based on published biochemical measurements, to investigate this question and to evaluate whether dopamine signaling exhibits spatial specificity post-synaptically. The model was stimulated with dopamine pulses mimicking those recorded in response to reward. Simulations show that PKA colocalization with adenylate cyclase, either in the spine head or in the dendrite, leads to greater phosphorylation of DARPP-32 Thr34 and AMPA receptor GluA1 Ser845 than when PKA is anchored away from adenylate cyclase. Simulations further demonstrate that though cAMP exhibits a strong spatial gradient, diffusible DARPP-32 facilitates the spread of PKA activity, suggesting that additional inactivation mechanisms are required to produce spatial specificity of PKA activity

Le soubassement volcanique de l'atoll de Fangataufa (Geologie-Petrologie)

INIST T 74648 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Etude de la cinetique d'hydrolyse de la caseine beta bovine par la chymosine et la pepsine bovines : influence du pH et de la force ionique

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Modulation des bioactivités LH et FSH de la eCG par les anticorps anti-eCG produits lors des traitements d'induction et de synchronisation de l'oestrus et de l'ovulation chez la chèvre

Lors des traitements hormonaux utilisés pour induire et synchroniser l'oestrus et l'ovulation, chez la chèvre, l'injection de la gonadotropine chorionique équine (eCG) induit, chez certaines femelles, une production d'anticorps anti-eCG (Ac) entraînant une mauvaise fertilité après insémination artificielle (IA). Nos travaux ont montré que ces Ac anti-eCG peuvent inhiber, potentialiser ou être sans effet sur l'une et/ou l'autre des deux bioactivités LH et FSH de la eCG in vitro et que le niveau de modulation des bioactivités de la eCG ne dépend pas de l'affinité des Ac pour la eCG. Les Ac sont principalement orientés contre les chaînes glycanniques spécifiques de la eCG, et particulièrement les acides sialiques. La modulation de la bioactivité FSH de la eCG par les Ac est cruciale pour les résultats de fertilité après traitement et IA : 100% de mise bas avec des Ac hyperstimulants de la bioactivité FSH et 0% avec des Ac inhibiteurs.During the hormonal treatments to induce and synchronize the oestrus and ovulation, in goat, the injection of the equine chorionic gonadotropine (eCG) induced, in some females, the production of anti-eCG antibody (Abs) involving a bad fertility after artificial insemination (AI). Our work showed that these anti-eCG Abs could inhibit, potentiate or to be without effect on one and/or the other of both LH and FSH bioactivites of the eCG in vitro and that the level of modulation of the bioactivities of the eCG does not depend on the affinity of Abs for the eCG. The Abs are oriented towards the glycannic chains specific to the eCG, and especially of the sialic acids. The modulation of FSH bioactivity of eCG by the Abs is crucial for the fertility results after treatment and AI : 100% of fertility with potentiated Abs of FSH bioactivity and 0% with inhibitory Abs.TOURS-BU Sciences Pharmacie (372612104) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

A critical evaluation of young (near-zero) K–Ar ages

International audienc