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Saint-Sauveur-en-Rue, France

Debroye E.,Catholic University of Leuven | Eliseeva S.V.,CNRS Center for Molecular Biophysics | Eliseeva S.V.,LE STUDIUM Institute for Advanced Studies | Laurent S.,University of Mons | And 4 more authors.
Dalton Transactions | Year: 2014

The synthesis and characterization of two novel DTPA bisamide derivatives DTPA-BC12PheA and DTPA-BC14PheA functionalized with p-dodecylaniline and p-tetradecylaniline are described. The ligands were coordinated to Gd(iii) and Eu(iii), resulting in highly paramagnetic and luminescent complexes, respectively. Mixed micelles consisting of Gd/Eu-DTPA-BC12PheA and DTPA-BC14PheA with a homogeneous size distribution (33-40 nm) were prepared by the assembly of the amphiphilic complexes with phospholipid DPPC and a surfactant Tween 80®. Taking into account the sensitivity difference between magnetic resonance and optical imaging techniques, the ratios of Gd and Eu complexes (Gd/Eu) 1:1, 2:1, 3:1, 20:1 and 50:1 were combined in one single micelle and their optical and relaxometric properties were characterized in detail. Upon excitation at 290 nm, the micelles display characteristic red emission bands due to the 5D0→7FJ (J = 0-4) transitions of Eu(iii). The number of water molecules in the first coordination sphere of Eu(iii) (qEu = 0.1-0.2) was calculated from the lifetime measurements performed in H2O and D2O solutions. Micelles composed of exclusively europium complexes display quantum yields in the range of 1.0%, decreasing with the europium concentration when going from 1:1 to 50:1 Gd/Eu contents. The ligand-to-lanthanide sensitization efficiency for micelles consisting of Eu-DTPA-BC12PheA and Eu-DTPA-BC14PheA equals 3.8% and 4.1%, respectively. The relaxivity r1 per Gd(iii) ion at 40 MHz and 310 K reaches a maximum value of 14.2 s-1 mM-1 for the Gd-DTPA-BC12PheA assemblies and 16.0 s-1 mM -1 for the micellar Gd-DTPA-BC14PheA assemblies compared to a value of 3.5 s-1 mM-1 for Gd-DTPA (Magnevist®). Theoretical fitting of the 1H NMRD profiles results in τR values of 4.2 to 6.6 ns. The optimal concentration ratio of Gd/Eu compounds in the micelles in order to provide the required bimodal performance has been determined to be 20:1. In the search for other bimodal systems, this discovery can be used as a guideline concerning the load of paramagnetic agents with respect to luminescent probes. © 2014 The Royal Society of Chemistry. Source


Westall F.,CNRS Center for Molecular Biophysics | Campbell K.A.,CNRS Center for Molecular Biophysics | Campbell K.A.,LE STUDIUM Institute for Advanced Studies | Campbell K.A.,University of Auckland | And 10 more authors.
Geology | Year: 2015

Interacting, diverse microbe-sediment systems exist in natural environments today but have not yet been recognized in the oldest records of life on Earth (older than 3.3 Ga) because of lack of distinctive biomarker molecules and patchy preservation of microbial paleocommunities. In an in-situ outcrop- to microbial-scale study, we have differentiated probable phototrophic, chemolithotrophic, and chemo-organotrophic fossil microbial signatures in a nearshore volcanogenic sedimentary setting in 3.33 Ga rocks of the Josefsdal Chert, Barberton greenstone belt, South Africa, while demonstrating the importance of contemporaneous hydrothermal activity. Hydrothermal fluids, as a nutrient source, strongly controlled the development and distribution of the microbial communities and, as a silicifying agent, contributed to their rapid fossilization. We thus show that intricate microbe-sediment systems are deep-rooted in time and that at least some early life may indeed have been thermophilic. © 2015 Geological Society of America. Source


Ulloa-Aguirre A.,French National Institute for Agricultural Research | Ulloa-Aguirre A.,French National Center for Scientific Research | Ulloa-Aguirre A.,University of Tours | Ulloa-Aguirre A.,LE STUDIUM Institute for Advanced Studies | And 13 more authors.
Reviews in Endocrine and Metabolic Disorders | Year: 2011

Gonadotropins play a central role in the control of male and female reproduction. Selective agonists and antagonists of gonadotropin receptors would be of great interest for the treatment of infertility or as non steroidal contraceptive. However, to date, only native hormones are being used in assisted reproduction technologies as there is no pharmacological agent available to manipulate gonadotropin receptors. Over the last decade, there has been a growing perception of the complexity associated with gonadotropin receptors' cellular signaling. It is now clear that the Gs/cAMP/PKA pathway is not the sole mechanism that must be taken into account in order to understand these hormones' biological actions. In parallel, consistent with the emerging paradigm of biased agonism, several examples of ligand-mediated selective signaling pathway activation by gonadotropin receptors have been reported. Small molecule ligands, modulating antibodies interacting with the hormones and glycosylation variants of the native glycoproteins have all demonstrated their potential to trigger such selective signaling. Altogether, the available data and emerging concepts give rise to intriguing opportunities towards a more efficient control of reproductive function and associated disorders. © Springer Science+Business Media, LLC 2011. Source


Laveuf C.,French National Institute for Agricultural Research | Cornu S.,French National Institute for Agricultural Research | Guilherme L.R.G.,French National Institute for Agricultural Research | Guilherme L.R.G.,LE STUDIUM Institute for Advanced Studies | And 3 more authors.
Geoderma | Year: 2012

Redox processes, which are widespread in soils, need to be quantified for an improved comprehension of the dynamics of Fe- and Mn-oxides and their associated trace elements. The classical methodology used to study these redox processes generally relies on the quantification of all mineral species in the various pedological features that can be related to different redox stages. However, this approach usually encounters the difficulty of precisely quantifying the different forms of poorly crystallised Fe- and Mn-oxides. In this study, we use the signature of rare earth elements (REEs) to visualise and, eventually, quantify the importance of redox processes in soils. Our approach relies on that developed by Laveuf et al. (2008) and the idea that the relative contribution to the mobilisation of REEs that is made by the primary minerals reactive to redox conditions depends on the following factors: (i) their initial proportion in the different pedological features that can be related to various redox processes, (ii) their relative mobilisation during the redox process in question, and (iii) their initial REE signatures. The catena studied is characterised by two stages of redox conditions: the first is related to the formation and subsequent dissolution of Fe-Mn concretions, and the second is related to the bleaching of the soil matrix due to morphological degradation. In this soil, the main minerals reactive to redox conditions are Mn-oxides, ferrihydrite, goethite and (fluor)apatite. The results indicate that the primary redox conditions can be characterised by a positive Ce anomaly on the REE pattern, which has been attributed to a preferential immobilisation of this element, due to its association with Mn-oxides. The results also indicate that the secondary redox conditions can be characterised by depletion in medium REEs (MREEs) in the REE pattern, which has been attributed to a preferential release of these elements during the dissolution of (fluor)apatite and, to a lesser extent, of ferrihydrite. These results emphasise the potential of REE signatures of the visualisation of the various redox processes that have been active in a soil. Additionally, REE signatures are a proxy of the frequency and intensity of the redox conditions. © 2011 Elsevier B.V. Source


Tranchant T.,CNRS Physiology of Reproduction and Behaviors | Tranchant T.,French National Center for Scientific Research | Tranchant T.,University of Tours | Tranchant T.,Laboratoire Of Biologie Of La Reproduction | And 20 more authors.
Molecular and Cellular Endocrinology | Year: 2011

The A189 V inactivating mutation of the human FSH receptor (FSHR) leads to subfertility in men and primary ovarian failure in women. This mutation has previously been associated with intracellular retention of the FSHR and impaired cAMP production. Here, we show that the A189 V FSHR stably expressed in HEK293N cells provoked ERK MAP kinases phosphorylation through β-arrestins, independently of the canonical cAMP/PKA pathway. Interesting, both the A189 V and wild-type (Wt) FSHRs selectively activated cAMP-independent ERK phosphorylation when expressed at low plasma membrane densities. These data indicate that the selective intracellular signalling triggered by the A189 V FSHR resulted from reduced membrane expression rather than by switching receptor coupling. Hence, receptor density at the plasma membrane might control the balance between distinct signal transduction mechanisms. Furthermore, our results help to clarify why mutations of FSHβ are more deleterious to human fertility than the FSHR A189 V mutation which preserves parts of receptor signalling repertoire. © 2010 Elsevier Ireland Ltd. Source

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